1 /* $NetBSD: pcap-linux.c,v 1.1.1.3 2013/04/06 15:57:48 christos Exp $ */ 2 3 /* 4 * pcap-linux.c: Packet capture interface to the Linux kernel 5 * 6 * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org> 7 * Sebastian Krahmer <krahmer@cs.uni-potsdam.de> 8 * 9 * License: BSD 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in 19 * the documentation and/or other materials provided with the 20 * distribution. 21 * 3. The names of the authors may not be used to endorse or promote 22 * products derived from this software without specific prior 23 * written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 27 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 28 * 29 * Modifications: Added PACKET_MMAP support 30 * Paolo Abeni <paolo.abeni@email.it> 31 * 32 * based on previous works of: 33 * Simon Patarin <patarin@cs.unibo.it> 34 * Phil Wood <cpw@lanl.gov> 35 * 36 * Monitor-mode support for mac80211 includes code taken from the iw 37 * command; the copyright notice for that code is 38 * 39 * Copyright (c) 2007, 2008 Johannes Berg 40 * Copyright (c) 2007 Andy Lutomirski 41 * Copyright (c) 2007 Mike Kershaw 42 * Copyright (c) 2008 Gábor Stefanik 43 * 44 * All rights reserved. 45 * 46 * Redistribution and use in source and binary forms, with or without 47 * modification, are permitted provided that the following conditions 48 * are met: 49 * 1. Redistributions of source code must retain the above copyright 50 * notice, this list of conditions and the following disclaimer. 51 * 2. Redistributions in binary form must reproduce the above copyright 52 * notice, this list of conditions and the following disclaimer in the 53 * documentation and/or other materials provided with the distribution. 54 * 3. The name of the author may not be used to endorse or promote products 55 * derived from this software without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 58 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 59 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 60 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 61 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 62 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 63 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 64 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 65 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 67 * SUCH DAMAGE. 68 */ 69 70 #ifndef lint 71 static const char rcsid[] _U_ = 72 "@(#) Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.164 2008-12-14 22:00:57 guy Exp (LBL)"; 73 #endif 74 75 /* 76 * Known problems with 2.0[.x] kernels: 77 * 78 * - The loopback device gives every packet twice; on 2.2[.x] kernels, 79 * if we use PF_PACKET, we can filter out the transmitted version 80 * of the packet by using data in the "sockaddr_ll" returned by 81 * "recvfrom()", but, on 2.0[.x] kernels, we have to use 82 * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a 83 * "sockaddr_pkt" which doesn't give us enough information to let 84 * us do that. 85 * 86 * - We have to set the interface's IFF_PROMISC flag ourselves, if 87 * we're to run in promiscuous mode, which means we have to turn 88 * it off ourselves when we're done; the kernel doesn't keep track 89 * of how many sockets are listening promiscuously, which means 90 * it won't get turned off automatically when no sockets are 91 * listening promiscuously. We catch "pcap_close()" and, for 92 * interfaces we put into promiscuous mode, take them out of 93 * promiscuous mode - which isn't necessarily the right thing to 94 * do, if another socket also requested promiscuous mode between 95 * the time when we opened the socket and the time when we close 96 * the socket. 97 * 98 * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()" 99 * return the amount of data that you could have read, rather than 100 * the amount that was returned, so we can't just allocate a buffer 101 * whose size is the snapshot length and pass the snapshot length 102 * as the byte count, and also pass MSG_TRUNC, so that the return 103 * value tells us how long the packet was on the wire. 104 * 105 * This means that, if we want to get the actual size of the packet, 106 * so we can return it in the "len" field of the packet header, 107 * we have to read the entire packet, not just the part that fits 108 * within the snapshot length, and thus waste CPU time copying data 109 * from the kernel that our caller won't see. 110 * 111 * We have to get the actual size, and supply it in "len", because 112 * otherwise, the IP dissector in tcpdump, for example, will complain 113 * about "truncated-ip", as the packet will appear to have been 114 * shorter, on the wire, than the IP header said it should have been. 115 */ 116 117 118 #define _GNU_SOURCE 119 120 #ifdef HAVE_CONFIG_H 121 #include "config.h" 122 #endif 123 124 #include <errno.h> 125 #include <stdio.h> 126 #include <stdlib.h> 127 #include <ctype.h> 128 #include <unistd.h> 129 #include <fcntl.h> 130 #include <string.h> 131 #include <limits.h> 132 #include <sys/socket.h> 133 #include <sys/ioctl.h> 134 #include <sys/utsname.h> 135 #include <sys/mman.h> 136 #include <linux/if.h> 137 #include <netinet/in.h> 138 #include <linux/if_ether.h> 139 #include <net/if_arp.h> 140 #include <poll.h> 141 #include <dirent.h> 142 143 #include "pcap-int.h" 144 #include "pcap/sll.h" 145 #include "pcap/vlan.h" 146 147 #ifdef HAVE_DAG_API 148 #include "pcap-dag.h" 149 #endif /* HAVE_DAG_API */ 150 151 #ifdef HAVE_SEPTEL_API 152 #include "pcap-septel.h" 153 #endif /* HAVE_SEPTEL_API */ 154 155 #ifdef HAVE_SNF_API 156 #include "pcap-snf.h" 157 #endif /* HAVE_SNF_API */ 158 159 #ifdef PCAP_SUPPORT_USB 160 #include "pcap-usb-linux.h" 161 #endif 162 163 #ifdef PCAP_SUPPORT_BT 164 #include "pcap-bt-linux.h" 165 #endif 166 167 #ifdef PCAP_SUPPORT_CAN 168 #include "pcap-can-linux.h" 169 #endif 170 171 #if PCAP_SUPPORT_CANUSB 172 #include "pcap-canusb-linux.h" 173 #endif 174 175 #ifdef PCAP_SUPPORT_NETFILTER 176 #include "pcap-netfilter-linux.h" 177 #endif 178 179 /* 180 * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET 181 * sockets rather than SOCK_PACKET sockets. 182 * 183 * To use them, we include <linux/if_packet.h> rather than 184 * <netpacket/packet.h>; we do so because 185 * 186 * some Linux distributions (e.g., Slackware 4.0) have 2.2 or 187 * later kernels and libc5, and don't provide a <netpacket/packet.h> 188 * file; 189 * 190 * not all versions of glibc2 have a <netpacket/packet.h> file 191 * that defines stuff needed for some of the 2.4-or-later-kernel 192 * features, so if the system has a 2.4 or later kernel, we 193 * still can't use those features. 194 * 195 * We're already including a number of other <linux/XXX.h> headers, and 196 * this code is Linux-specific (no other OS has PF_PACKET sockets as 197 * a raw packet capture mechanism), so it's not as if you gain any 198 * useful portability by using <netpacket/packet.h> 199 * 200 * XXX - should we just include <linux/if_packet.h> even if PF_PACKET 201 * isn't defined? It only defines one data structure in 2.0.x, so 202 * it shouldn't cause any problems. 203 */ 204 #ifdef PF_PACKET 205 # include <linux/if_packet.h> 206 207 /* 208 * On at least some Linux distributions (for example, Red Hat 5.2), 209 * there's no <netpacket/packet.h> file, but PF_PACKET is defined if 210 * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define 211 * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of 212 * the PACKET_xxx stuff. 213 * 214 * So we check whether PACKET_HOST is defined, and assume that we have 215 * PF_PACKET sockets only if it is defined. 216 */ 217 # ifdef PACKET_HOST 218 # define HAVE_PF_PACKET_SOCKETS 219 # ifdef PACKET_AUXDATA 220 # define HAVE_PACKET_AUXDATA 221 # endif /* PACKET_AUXDATA */ 222 # endif /* PACKET_HOST */ 223 224 225 /* check for memory mapped access avaibility. We assume every needed 226 * struct is defined if the macro TPACKET_HDRLEN is defined, because it 227 * uses many ring related structs and macros */ 228 # ifdef TPACKET_HDRLEN 229 # define HAVE_PACKET_RING 230 # ifdef TPACKET2_HDRLEN 231 # define HAVE_TPACKET2 232 # else 233 # define TPACKET_V1 0 234 # endif /* TPACKET2_HDRLEN */ 235 # endif /* TPACKET_HDRLEN */ 236 #endif /* PF_PACKET */ 237 238 #ifdef SO_ATTACH_FILTER 239 #include <linux/types.h> 240 #include <linux/filter.h> 241 #endif 242 243 /* 244 * We need linux/sockios.h if we have linux/net_tstamp.h (for time stamp 245 * specification) or linux/ethtool.h (for ethtool ioctls to get offloading 246 * information). 247 */ 248 #if defined(HAVE_LINUX_NET_TSTAMP_H) || defined(HAVE_LINUX_ETHTOOL_H) 249 #include <linux/sockios.h> 250 #endif 251 252 #ifdef HAVE_LINUX_NET_TSTAMP_H 253 #include <linux/net_tstamp.h> 254 #endif 255 256 /* 257 * Got Wireless Extensions? 258 */ 259 #ifdef HAVE_LINUX_WIRELESS_H 260 #include <linux/wireless.h> 261 #endif /* HAVE_LINUX_WIRELESS_H */ 262 263 /* 264 * Got libnl? 265 */ 266 #ifdef HAVE_LIBNL 267 #include <linux/nl80211.h> 268 269 #include <netlink/genl/genl.h> 270 #include <netlink/genl/family.h> 271 #include <netlink/genl/ctrl.h> 272 #include <netlink/msg.h> 273 #include <netlink/attr.h> 274 #endif /* HAVE_LIBNL */ 275 276 /* 277 * Got ethtool support? 278 */ 279 #ifdef HAVE_LINUX_ETHTOOL_H 280 #include <linux/ethtool.h> 281 #endif 282 283 #ifndef HAVE_SOCKLEN_T 284 typedef int socklen_t; 285 #endif 286 287 #ifndef MSG_TRUNC 288 /* 289 * This is being compiled on a system that lacks MSG_TRUNC; define it 290 * with the value it has in the 2.2 and later kernels, so that, on 291 * those kernels, when we pass it in the flags argument to "recvfrom()" 292 * we're passing the right value and thus get the MSG_TRUNC behavior 293 * we want. (We don't get that behavior on 2.0[.x] kernels, because 294 * they didn't support MSG_TRUNC.) 295 */ 296 #define MSG_TRUNC 0x20 297 #endif 298 299 #ifndef SOL_PACKET 300 /* 301 * This is being compiled on a system that lacks SOL_PACKET; define it 302 * with the value it has in the 2.2 and later kernels, so that we can 303 * set promiscuous mode in the good modern way rather than the old 304 * 2.0-kernel crappy way. 305 */ 306 #define SOL_PACKET 263 307 #endif 308 309 #define MAX_LINKHEADER_SIZE 256 310 311 /* 312 * When capturing on all interfaces we use this as the buffer size. 313 * Should be bigger then all MTUs that occur in real life. 314 * 64kB should be enough for now. 315 */ 316 #define BIGGER_THAN_ALL_MTUS (64*1024) 317 318 /* 319 * Prototypes for internal functions and methods. 320 */ 321 static void map_arphrd_to_dlt(pcap_t *, int, int); 322 #ifdef HAVE_PF_PACKET_SOCKETS 323 static short int map_packet_type_to_sll_type(short int); 324 #endif 325 static int pcap_activate_linux(pcap_t *); 326 static int activate_old(pcap_t *); 327 static int activate_new(pcap_t *); 328 static int activate_mmap(pcap_t *, int *); 329 static int pcap_can_set_rfmon_linux(pcap_t *); 330 static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *); 331 static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); 332 static int pcap_inject_linux(pcap_t *, const void *, size_t); 333 static int pcap_stats_linux(pcap_t *, struct pcap_stat *); 334 static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); 335 static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); 336 static void pcap_cleanup_linux(pcap_t *); 337 338 union thdr { 339 struct tpacket_hdr *h1; 340 struct tpacket2_hdr *h2; 341 void *raw; 342 }; 343 344 #ifdef HAVE_PACKET_RING 345 #define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset]) 346 347 static void destroy_ring(pcap_t *handle); 348 static int create_ring(pcap_t *handle, int *status); 349 static int prepare_tpacket_socket(pcap_t *handle); 350 static void pcap_cleanup_linux_mmap(pcap_t *); 351 static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *); 352 static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); 353 static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf); 354 static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf); 355 static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, 356 const u_char *bytes); 357 #endif 358 359 /* 360 * Wrap some ioctl calls 361 */ 362 #ifdef HAVE_PF_PACKET_SOCKETS 363 static int iface_get_id(int fd, const char *device, char *ebuf); 364 #endif /* HAVE_PF_PACKET_SOCKETS */ 365 static int iface_get_mtu(int fd, const char *device, char *ebuf); 366 static int iface_get_arptype(int fd, const char *device, char *ebuf); 367 #ifdef HAVE_PF_PACKET_SOCKETS 368 static int iface_bind(int fd, int ifindex, char *ebuf); 369 #ifdef IW_MODE_MONITOR 370 static int has_wext(int sock_fd, const char *device, char *ebuf); 371 #endif /* IW_MODE_MONITOR */ 372 static int enter_rfmon_mode(pcap_t *handle, int sock_fd, 373 const char *device); 374 #endif /* HAVE_PF_PACKET_SOCKETS */ 375 static int iface_get_offload(pcap_t *handle); 376 static int iface_bind_old(int fd, const char *device, char *ebuf); 377 378 #ifdef SO_ATTACH_FILTER 379 static int fix_program(pcap_t *handle, struct sock_fprog *fcode, 380 int is_mapped); 381 static int fix_offset(struct bpf_insn *p); 382 static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); 383 static int reset_kernel_filter(pcap_t *handle); 384 385 static struct sock_filter total_insn 386 = BPF_STMT(BPF_RET | BPF_K, 0); 387 static struct sock_fprog total_fcode 388 = { 1, &total_insn }; 389 #endif /* SO_ATTACH_FILTER */ 390 391 pcap_t * 392 pcap_create(const char *device, char *ebuf) 393 { 394 pcap_t *handle; 395 396 /* 397 * A null device name is equivalent to the "any" device. 398 */ 399 if (device == NULL) 400 device = "any"; 401 402 #ifdef HAVE_DAG_API 403 if (strstr(device, "dag")) { 404 return dag_create(device, ebuf); 405 } 406 #endif /* HAVE_DAG_API */ 407 408 #ifdef HAVE_SEPTEL_API 409 if (strstr(device, "septel")) { 410 return septel_create(device, ebuf); 411 } 412 #endif /* HAVE_SEPTEL_API */ 413 414 #ifdef HAVE_SNF_API 415 handle = snf_create(device, ebuf); 416 if (strstr(device, "snf") || handle != NULL) 417 return handle; 418 419 #endif /* HAVE_SNF_API */ 420 421 #ifdef PCAP_SUPPORT_BT 422 if (strstr(device, "bluetooth")) { 423 return bt_create(device, ebuf); 424 } 425 #endif 426 427 #if PCAP_SUPPORT_CANUSB 428 if (strstr(device, "canusb")) { 429 return canusb_create(device, ebuf); 430 } 431 #endif 432 433 #ifdef PCAP_SUPPORT_CAN 434 if ((strncmp(device, "can", 3) == 0 && isdigit(device[3])) || 435 (strncmp(device, "vcan", 4) == 0 && isdigit(device[4]))) { 436 return can_create(device, ebuf); 437 } 438 #endif 439 440 #ifdef PCAP_SUPPORT_USB 441 if (strstr(device, "usbmon")) { 442 return usb_create(device, ebuf); 443 } 444 #endif 445 446 #ifdef PCAP_SUPPORT_NETFILTER 447 if (strncmp(device, "nflog", strlen("nflog")) == 0) { 448 return nflog_create(device, ebuf); 449 } 450 #endif 451 452 handle = pcap_create_common(device, ebuf); 453 if (handle == NULL) 454 return NULL; 455 456 handle->activate_op = pcap_activate_linux; 457 handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; 458 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) 459 /* 460 * We claim that we support: 461 * 462 * software time stamps, with no details about their precision; 463 * hardware time stamps, synced to the host time; 464 * hardware time stamps, not synced to the host time. 465 * 466 * XXX - we can't ask a device whether it supports 467 * hardware time stamps, so we just claim all devices do. 468 */ 469 handle->tstamp_type_count = 3; 470 handle->tstamp_type_list = malloc(3 * sizeof(u_int)); 471 if (handle->tstamp_type_list == NULL) { 472 free(handle); 473 return NULL; 474 } 475 handle->tstamp_type_list[0] = PCAP_TSTAMP_HOST; 476 handle->tstamp_type_list[1] = PCAP_TSTAMP_ADAPTER; 477 handle->tstamp_type_list[2] = PCAP_TSTAMP_ADAPTER_UNSYNCED; 478 #endif 479 480 return handle; 481 } 482 483 #ifdef HAVE_LIBNL 484 /* 485 * If interface {if} is a mac80211 driver, the file 486 * /sys/class/net/{if}/phy80211 is a symlink to 487 * /sys/class/ieee80211/{phydev}, for some {phydev}. 488 * 489 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at 490 * least, has a "wmaster0" device and a "wlan0" device; the 491 * latter is the one with the IP address. Both show up in 492 * "tcpdump -D" output. Capturing on the wmaster0 device 493 * captures with 802.11 headers. 494 * 495 * airmon-ng searches through /sys/class/net for devices named 496 * monN, starting with mon0; as soon as one *doesn't* exist, 497 * it chooses that as the monitor device name. If the "iw" 498 * command exists, it does "iw dev {if} interface add {monif} 499 * type monitor", where {monif} is the monitor device. It 500 * then (sigh) sleeps .1 second, and then configures the 501 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface 502 * is a file, it writes {mondev}, without a newline, to that file, 503 * and again (sigh) sleeps .1 second, and then iwconfig's that 504 * device into monitor mode and configures it up. Otherwise, 505 * you can't do monitor mode. 506 * 507 * All these devices are "glued" together by having the 508 * /sys/class/net/{device}/phy80211 links pointing to the same 509 * place, so, given a wmaster, wlan, or mon device, you can 510 * find the other devices by looking for devices with 511 * the same phy80211 link. 512 * 513 * To turn monitor mode off, delete the monitor interface, 514 * either with "iw dev {monif} interface del" or by sending 515 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface 516 * 517 * Note: if you try to create a monitor device named "monN", and 518 * there's already a "monN" device, it fails, as least with 519 * the netlink interface (which is what iw uses), with a return 520 * value of -ENFILE. (Return values are negative errnos.) We 521 * could probably use that to find an unused device. 522 * 523 * Yes, you can have multiple monitor devices for a given 524 * physical device. 525 */ 526 527 /* 528 * Is this a mac80211 device? If so, fill in the physical device path and 529 * return 1; if not, return 0. On an error, fill in handle->errbuf and 530 * return PCAP_ERROR. 531 */ 532 static int 533 get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, 534 size_t phydev_max_pathlen) 535 { 536 char *pathstr; 537 ssize_t bytes_read; 538 539 /* 540 * Generate the path string for the symlink to the physical device. 541 */ 542 if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { 543 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 544 "%s: Can't generate path name string for /sys/class/net device", 545 device); 546 return PCAP_ERROR; 547 } 548 bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); 549 if (bytes_read == -1) { 550 if (errno == ENOENT || errno == EINVAL) { 551 /* 552 * Doesn't exist, or not a symlink; assume that 553 * means it's not a mac80211 device. 554 */ 555 free(pathstr); 556 return 0; 557 } 558 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 559 "%s: Can't readlink %s: %s", device, pathstr, 560 strerror(errno)); 561 free(pathstr); 562 return PCAP_ERROR; 563 } 564 free(pathstr); 565 phydev_path[bytes_read] = '\0'; 566 return 1; 567 } 568 569 #ifdef HAVE_LIBNL_2_x 570 #define get_nl_errmsg nl_geterror 571 #else 572 /* libnl 2.x compatibility code */ 573 574 #define nl_sock nl_handle 575 576 static inline struct nl_handle * 577 nl_socket_alloc(void) 578 { 579 return nl_handle_alloc(); 580 } 581 582 static inline void 583 nl_socket_free(struct nl_handle *h) 584 { 585 nl_handle_destroy(h); 586 } 587 588 #define get_nl_errmsg strerror 589 590 static inline int 591 __genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache) 592 { 593 struct nl_cache *tmp = genl_ctrl_alloc_cache(h); 594 if (!tmp) 595 return -ENOMEM; 596 *cache = tmp; 597 return 0; 598 } 599 #define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache 600 #endif /* !HAVE_LIBNL_2_x */ 601 602 struct nl80211_state { 603 struct nl_sock *nl_sock; 604 struct nl_cache *nl_cache; 605 struct genl_family *nl80211; 606 }; 607 608 static int 609 nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) 610 { 611 int err; 612 613 state->nl_sock = nl_socket_alloc(); 614 if (!state->nl_sock) { 615 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 616 "%s: failed to allocate netlink handle", device); 617 return PCAP_ERROR; 618 } 619 620 if (genl_connect(state->nl_sock)) { 621 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 622 "%s: failed to connect to generic netlink", device); 623 goto out_handle_destroy; 624 } 625 626 err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache); 627 if (err < 0) { 628 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 629 "%s: failed to allocate generic netlink cache: %s", 630 device, get_nl_errmsg(-err)); 631 goto out_handle_destroy; 632 } 633 634 state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); 635 if (!state->nl80211) { 636 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 637 "%s: nl80211 not found", device); 638 goto out_cache_free; 639 } 640 641 return 0; 642 643 out_cache_free: 644 nl_cache_free(state->nl_cache); 645 out_handle_destroy: 646 nl_socket_free(state->nl_sock); 647 return PCAP_ERROR; 648 } 649 650 static void 651 nl80211_cleanup(struct nl80211_state *state) 652 { 653 genl_family_put(state->nl80211); 654 nl_cache_free(state->nl_cache); 655 nl_socket_free(state->nl_sock); 656 } 657 658 static int 659 add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, 660 const char *device, const char *mondevice) 661 { 662 int ifindex; 663 struct nl_msg *msg; 664 int err; 665 666 ifindex = iface_get_id(sock_fd, device, handle->errbuf); 667 if (ifindex == -1) 668 return PCAP_ERROR; 669 670 msg = nlmsg_alloc(); 671 if (!msg) { 672 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 673 "%s: failed to allocate netlink msg", device); 674 return PCAP_ERROR; 675 } 676 677 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 678 0, NL80211_CMD_NEW_INTERFACE, 0); 679 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); 680 NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); 681 NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); 682 683 err = nl_send_auto_complete(state->nl_sock, msg); 684 if (err < 0) { 685 #ifdef HAVE_LIBNL_2_x 686 if (err == -NLE_FAILURE) { 687 #else 688 if (err == -ENFILE) { 689 #endif 690 /* 691 * Device not available; our caller should just 692 * keep trying. (libnl 2.x maps ENFILE to 693 * NLE_FAILURE; it can also map other errors 694 * to that, but there's not much we can do 695 * about that.) 696 */ 697 nlmsg_free(msg); 698 return 0; 699 } else { 700 /* 701 * Real failure, not just "that device is not 702 * available. 703 */ 704 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 705 "%s: nl_send_auto_complete failed adding %s interface: %s", 706 device, mondevice, get_nl_errmsg(-err)); 707 nlmsg_free(msg); 708 return PCAP_ERROR; 709 } 710 } 711 err = nl_wait_for_ack(state->nl_sock); 712 if (err < 0) { 713 #ifdef HAVE_LIBNL_2_x 714 if (err == -NLE_FAILURE) { 715 #else 716 if (err == -ENFILE) { 717 #endif 718 /* 719 * Device not available; our caller should just 720 * keep trying. (libnl 2.x maps ENFILE to 721 * NLE_FAILURE; it can also map other errors 722 * to that, but there's not much we can do 723 * about that.) 724 */ 725 nlmsg_free(msg); 726 return 0; 727 } else { 728 /* 729 * Real failure, not just "that device is not 730 * available. 731 */ 732 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 733 "%s: nl_wait_for_ack failed adding %s interface: %s", 734 device, mondevice, get_nl_errmsg(-err)); 735 nlmsg_free(msg); 736 return PCAP_ERROR; 737 } 738 } 739 740 /* 741 * Success. 742 */ 743 nlmsg_free(msg); 744 return 1; 745 746 nla_put_failure: 747 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 748 "%s: nl_put failed adding %s interface", 749 device, mondevice); 750 nlmsg_free(msg); 751 return PCAP_ERROR; 752 } 753 754 static int 755 del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, 756 const char *device, const char *mondevice) 757 { 758 int ifindex; 759 struct nl_msg *msg; 760 int err; 761 762 ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); 763 if (ifindex == -1) 764 return PCAP_ERROR; 765 766 msg = nlmsg_alloc(); 767 if (!msg) { 768 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 769 "%s: failed to allocate netlink msg", device); 770 return PCAP_ERROR; 771 } 772 773 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 774 0, NL80211_CMD_DEL_INTERFACE, 0); 775 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); 776 777 err = nl_send_auto_complete(state->nl_sock, msg); 778 if (err < 0) { 779 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 780 "%s: nl_send_auto_complete failed deleting %s interface: %s", 781 device, mondevice, get_nl_errmsg(-err)); 782 nlmsg_free(msg); 783 return PCAP_ERROR; 784 } 785 err = nl_wait_for_ack(state->nl_sock); 786 if (err < 0) { 787 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 788 "%s: nl_wait_for_ack failed adding %s interface: %s", 789 device, mondevice, get_nl_errmsg(-err)); 790 nlmsg_free(msg); 791 return PCAP_ERROR; 792 } 793 794 /* 795 * Success. 796 */ 797 nlmsg_free(msg); 798 return 1; 799 800 nla_put_failure: 801 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 802 "%s: nl_put failed deleting %s interface", 803 device, mondevice); 804 nlmsg_free(msg); 805 return PCAP_ERROR; 806 } 807 808 static int 809 enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) 810 { 811 int ret; 812 char phydev_path[PATH_MAX+1]; 813 struct nl80211_state nlstate; 814 struct ifreq ifr; 815 u_int n; 816 817 /* 818 * Is this a mac80211 device? 819 */ 820 ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); 821 if (ret < 0) 822 return ret; /* error */ 823 if (ret == 0) 824 return 0; /* no error, but not mac80211 device */ 825 826 /* 827 * XXX - is this already a monN device? 828 * If so, we're done. 829 * Is that determined by old Wireless Extensions ioctls? 830 */ 831 832 /* 833 * OK, it's apparently a mac80211 device. 834 * Try to find an unused monN device for it. 835 */ 836 ret = nl80211_init(handle, &nlstate, device); 837 if (ret != 0) 838 return ret; 839 for (n = 0; n < UINT_MAX; n++) { 840 /* 841 * Try mon{n}. 842 */ 843 char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ 844 845 snprintf(mondevice, sizeof mondevice, "mon%u", n); 846 ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); 847 if (ret == 1) { 848 handle->md.mondevice = strdup(mondevice); 849 goto added; 850 } 851 if (ret < 0) { 852 /* 853 * Hard failure. Just return ret; handle->errbuf 854 * has already been set. 855 */ 856 nl80211_cleanup(&nlstate); 857 return ret; 858 } 859 } 860 861 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 862 "%s: No free monN interfaces", device); 863 nl80211_cleanup(&nlstate); 864 return PCAP_ERROR; 865 866 added: 867 868 #if 0 869 /* 870 * Sleep for .1 seconds. 871 */ 872 delay.tv_sec = 0; 873 delay.tv_nsec = 500000000; 874 nanosleep(&delay, NULL); 875 #endif 876 877 /* 878 * If we haven't already done so, arrange to have 879 * "pcap_close_all()" called when we exit. 880 */ 881 if (!pcap_do_addexit(handle)) { 882 /* 883 * "atexit()" failed; don't put the interface 884 * in rfmon mode, just give up. 885 */ 886 return PCAP_ERROR_RFMON_NOTSUP; 887 } 888 889 /* 890 * Now configure the monitor interface up. 891 */ 892 memset(&ifr, 0, sizeof(ifr)); 893 strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name)); 894 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { 895 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 896 "%s: Can't get flags for %s: %s", device, 897 handle->md.mondevice, strerror(errno)); 898 del_mon_if(handle, sock_fd, &nlstate, device, 899 handle->md.mondevice); 900 nl80211_cleanup(&nlstate); 901 return PCAP_ERROR; 902 } 903 ifr.ifr_flags |= IFF_UP|IFF_RUNNING; 904 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 905 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 906 "%s: Can't set flags for %s: %s", device, 907 handle->md.mondevice, strerror(errno)); 908 del_mon_if(handle, sock_fd, &nlstate, device, 909 handle->md.mondevice); 910 nl80211_cleanup(&nlstate); 911 return PCAP_ERROR; 912 } 913 914 /* 915 * Success. Clean up the libnl state. 916 */ 917 nl80211_cleanup(&nlstate); 918 919 /* 920 * Note that we have to delete the monitor device when we close 921 * the handle. 922 */ 923 handle->md.must_do_on_close |= MUST_DELETE_MONIF; 924 925 /* 926 * Add this to the list of pcaps to close when we exit. 927 */ 928 pcap_add_to_pcaps_to_close(handle); 929 930 return 1; 931 } 932 #endif /* HAVE_LIBNL */ 933 934 static int 935 pcap_can_set_rfmon_linux(pcap_t *handle) 936 { 937 #ifdef HAVE_LIBNL 938 char phydev_path[PATH_MAX+1]; 939 int ret; 940 #endif 941 #ifdef IW_MODE_MONITOR 942 int sock_fd; 943 struct iwreq ireq; 944 #endif 945 946 if (strcmp(handle->opt.source, "any") == 0) { 947 /* 948 * Monitor mode makes no sense on the "any" device. 949 */ 950 return 0; 951 } 952 953 #ifdef HAVE_LIBNL 954 /* 955 * Bleah. There doesn't seem to be a way to ask a mac80211 956 * device, through libnl, whether it supports monitor mode; 957 * we'll just check whether the device appears to be a 958 * mac80211 device and, if so, assume the device supports 959 * monitor mode. 960 * 961 * wmaster devices don't appear to support the Wireless 962 * Extensions, but we can create a mon device for a 963 * wmaster device, so we don't bother checking whether 964 * a mac80211 device supports the Wireless Extensions. 965 */ 966 ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path, 967 PATH_MAX); 968 if (ret < 0) 969 return ret; /* error */ 970 if (ret == 1) 971 return 1; /* mac80211 device */ 972 #endif 973 974 #ifdef IW_MODE_MONITOR 975 /* 976 * Bleah. There doesn't appear to be an ioctl to use to ask 977 * whether a device supports monitor mode; we'll just do 978 * SIOCGIWMODE and, if it succeeds, assume the device supports 979 * monitor mode. 980 * 981 * Open a socket on which to attempt to get the mode. 982 * (We assume that if we have Wireless Extensions support 983 * we also have PF_PACKET support.) 984 */ 985 sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); 986 if (sock_fd == -1) { 987 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 988 "socket: %s", pcap_strerror(errno)); 989 return PCAP_ERROR; 990 } 991 992 /* 993 * Attempt to get the current mode. 994 */ 995 strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source, 996 sizeof ireq.ifr_ifrn.ifrn_name); 997 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 998 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { 999 /* 1000 * Well, we got the mode; assume we can set it. 1001 */ 1002 close(sock_fd); 1003 return 1; 1004 } 1005 if (errno == ENODEV) { 1006 /* The device doesn't even exist. */ 1007 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1008 "SIOCGIWMODE failed: %s", pcap_strerror(errno)); 1009 close(sock_fd); 1010 return PCAP_ERROR_NO_SUCH_DEVICE; 1011 } 1012 close(sock_fd); 1013 #endif 1014 return 0; 1015 } 1016 1017 /* 1018 * Grabs the number of dropped packets by the interface from /proc/net/dev. 1019 * 1020 * XXX - what about /sys/class/net/{interface name}/rx_*? There are 1021 * individual devices giving, in ASCII, various rx_ and tx_ statistics. 1022 * 1023 * Or can we get them in binary form from netlink? 1024 */ 1025 static long int 1026 linux_if_drops(const char * if_name) 1027 { 1028 char buffer[512]; 1029 char * bufptr; 1030 FILE * file; 1031 int field_to_convert = 3, if_name_sz = strlen(if_name); 1032 long int dropped_pkts = 0; 1033 1034 file = fopen("/proc/net/dev", "r"); 1035 if (!file) 1036 return 0; 1037 1038 while (!dropped_pkts && fgets( buffer, sizeof(buffer), file )) 1039 { 1040 /* search for 'bytes' -- if its in there, then 1041 that means we need to grab the fourth field. otherwise 1042 grab the third field. */ 1043 if (field_to_convert != 4 && strstr(buffer, "bytes")) 1044 { 1045 field_to_convert = 4; 1046 continue; 1047 } 1048 1049 /* find iface and make sure it actually matches -- space before the name and : after it */ 1050 if ((bufptr = strstr(buffer, if_name)) && 1051 (bufptr == buffer || *(bufptr-1) == ' ') && 1052 *(bufptr + if_name_sz) == ':') 1053 { 1054 bufptr = bufptr + if_name_sz + 1; 1055 1056 /* grab the nth field from it */ 1057 while( --field_to_convert && *bufptr != '\0') 1058 { 1059 while (*bufptr != '\0' && *(bufptr++) == ' '); 1060 while (*bufptr != '\0' && *(bufptr++) != ' '); 1061 } 1062 1063 /* get rid of any final spaces */ 1064 while (*bufptr != '\0' && *bufptr == ' ') bufptr++; 1065 1066 if (*bufptr != '\0') 1067 dropped_pkts = strtol(bufptr, NULL, 10); 1068 1069 break; 1070 } 1071 } 1072 1073 fclose(file); 1074 return dropped_pkts; 1075 } 1076 1077 1078 /* 1079 * With older kernels promiscuous mode is kind of interesting because we 1080 * have to reset the interface before exiting. The problem can't really 1081 * be solved without some daemon taking care of managing usage counts. 1082 * If we put the interface into promiscuous mode, we set a flag indicating 1083 * that we must take it out of that mode when the interface is closed, 1084 * and, when closing the interface, if that flag is set we take it out 1085 * of promiscuous mode. 1086 * 1087 * Even with newer kernels, we have the same issue with rfmon mode. 1088 */ 1089 1090 static void pcap_cleanup_linux( pcap_t *handle ) 1091 { 1092 struct ifreq ifr; 1093 #ifdef HAVE_LIBNL 1094 struct nl80211_state nlstate; 1095 int ret; 1096 #endif /* HAVE_LIBNL */ 1097 #ifdef IW_MODE_MONITOR 1098 int oldflags; 1099 struct iwreq ireq; 1100 #endif /* IW_MODE_MONITOR */ 1101 1102 if (handle->md.must_do_on_close != 0) { 1103 /* 1104 * There's something we have to do when closing this 1105 * pcap_t. 1106 */ 1107 if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) { 1108 /* 1109 * We put the interface into promiscuous mode; 1110 * take it out of promiscuous mode. 1111 * 1112 * XXX - if somebody else wants it in promiscuous 1113 * mode, this code cannot know that, so it'll take 1114 * it out of promiscuous mode. That's not fixable 1115 * in 2.0[.x] kernels. 1116 */ 1117 memset(&ifr, 0, sizeof(ifr)); 1118 strncpy(ifr.ifr_name, handle->md.device, 1119 sizeof(ifr.ifr_name)); 1120 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { 1121 fprintf(stderr, 1122 "Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n" 1123 "Please adjust manually.\n" 1124 "Hint: This can't happen with Linux >= 2.2.0.\n", 1125 handle->md.device, strerror(errno)); 1126 } else { 1127 if (ifr.ifr_flags & IFF_PROMISC) { 1128 /* 1129 * Promiscuous mode is currently on; 1130 * turn it off. 1131 */ 1132 ifr.ifr_flags &= ~IFF_PROMISC; 1133 if (ioctl(handle->fd, SIOCSIFFLAGS, 1134 &ifr) == -1) { 1135 fprintf(stderr, 1136 "Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n" 1137 "Please adjust manually.\n" 1138 "Hint: This can't happen with Linux >= 2.2.0.\n", 1139 handle->md.device, 1140 strerror(errno)); 1141 } 1142 } 1143 } 1144 } 1145 1146 #ifdef HAVE_LIBNL 1147 if (handle->md.must_do_on_close & MUST_DELETE_MONIF) { 1148 ret = nl80211_init(handle, &nlstate, handle->md.device); 1149 if (ret >= 0) { 1150 ret = del_mon_if(handle, handle->fd, &nlstate, 1151 handle->md.device, handle->md.mondevice); 1152 nl80211_cleanup(&nlstate); 1153 } 1154 if (ret < 0) { 1155 fprintf(stderr, 1156 "Can't delete monitor interface %s (%s).\n" 1157 "Please delete manually.\n", 1158 handle->md.mondevice, handle->errbuf); 1159 } 1160 } 1161 #endif /* HAVE_LIBNL */ 1162 1163 #ifdef IW_MODE_MONITOR 1164 if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) { 1165 /* 1166 * We put the interface into rfmon mode; 1167 * take it out of rfmon mode. 1168 * 1169 * XXX - if somebody else wants it in rfmon 1170 * mode, this code cannot know that, so it'll take 1171 * it out of rfmon mode. 1172 */ 1173 1174 /* 1175 * First, take the interface down if it's up; 1176 * otherwise, we might get EBUSY. 1177 * If we get errors, just drive on and print 1178 * a warning if we can't restore the mode. 1179 */ 1180 oldflags = 0; 1181 memset(&ifr, 0, sizeof(ifr)); 1182 strncpy(ifr.ifr_name, handle->md.device, 1183 sizeof(ifr.ifr_name)); 1184 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) { 1185 if (ifr.ifr_flags & IFF_UP) { 1186 oldflags = ifr.ifr_flags; 1187 ifr.ifr_flags &= ~IFF_UP; 1188 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) 1189 oldflags = 0; /* didn't set, don't restore */ 1190 } 1191 } 1192 1193 /* 1194 * Now restore the mode. 1195 */ 1196 strncpy(ireq.ifr_ifrn.ifrn_name, handle->md.device, 1197 sizeof ireq.ifr_ifrn.ifrn_name); 1198 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] 1199 = 0; 1200 ireq.u.mode = handle->md.oldmode; 1201 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { 1202 /* 1203 * Scientist, you've failed. 1204 */ 1205 fprintf(stderr, 1206 "Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n" 1207 "Please adjust manually.\n", 1208 handle->md.device, strerror(errno)); 1209 } 1210 1211 /* 1212 * Now bring the interface back up if we brought 1213 * it down. 1214 */ 1215 if (oldflags != 0) { 1216 ifr.ifr_flags = oldflags; 1217 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { 1218 fprintf(stderr, 1219 "Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n" 1220 "Please adjust manually.\n", 1221 handle->md.device, strerror(errno)); 1222 } 1223 } 1224 } 1225 #endif /* IW_MODE_MONITOR */ 1226 1227 /* 1228 * Take this pcap out of the list of pcaps for which we 1229 * have to take the interface out of some mode. 1230 */ 1231 pcap_remove_from_pcaps_to_close(handle); 1232 } 1233 1234 if (handle->md.mondevice != NULL) { 1235 free(handle->md.mondevice); 1236 handle->md.mondevice = NULL; 1237 } 1238 if (handle->md.device != NULL) { 1239 free(handle->md.device); 1240 handle->md.device = NULL; 1241 } 1242 pcap_cleanup_live_common(handle); 1243 } 1244 1245 /* 1246 * Get a handle for a live capture from the given device. You can 1247 * pass NULL as device to get all packages (without link level 1248 * information of course). If you pass 1 as promisc the interface 1249 * will be set to promiscous mode (XXX: I think this usage should 1250 * be deprecated and functions be added to select that later allow 1251 * modification of that values -- Torsten). 1252 */ 1253 static int 1254 pcap_activate_linux(pcap_t *handle) 1255 { 1256 const char *device; 1257 int status = 0; 1258 1259 device = handle->opt.source; 1260 1261 handle->inject_op = pcap_inject_linux; 1262 handle->setfilter_op = pcap_setfilter_linux; 1263 handle->setdirection_op = pcap_setdirection_linux; 1264 handle->set_datalink_op = NULL; /* can't change data link type */ 1265 handle->getnonblock_op = pcap_getnonblock_fd; 1266 handle->setnonblock_op = pcap_setnonblock_fd; 1267 handle->cleanup_op = pcap_cleanup_linux; 1268 handle->read_op = pcap_read_linux; 1269 handle->stats_op = pcap_stats_linux; 1270 1271 /* 1272 * The "any" device is a special device which causes us not 1273 * to bind to a particular device and thus to look at all 1274 * devices. 1275 */ 1276 if (strcmp(device, "any") == 0) { 1277 if (handle->opt.promisc) { 1278 handle->opt.promisc = 0; 1279 /* Just a warning. */ 1280 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1281 "Promiscuous mode not supported on the \"any\" device"); 1282 status = PCAP_WARNING_PROMISC_NOTSUP; 1283 } 1284 } 1285 1286 handle->md.device = strdup(device); 1287 if (handle->md.device == NULL) { 1288 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s", 1289 pcap_strerror(errno) ); 1290 return PCAP_ERROR; 1291 } 1292 1293 /* 1294 * If we're in promiscuous mode, then we probably want 1295 * to see when the interface drops packets too, so get an 1296 * initial count from /proc/net/dev 1297 */ 1298 if (handle->opt.promisc) 1299 handle->md.proc_dropped = linux_if_drops(handle->md.device); 1300 1301 /* 1302 * Current Linux kernels use the protocol family PF_PACKET to 1303 * allow direct access to all packets on the network while 1304 * older kernels had a special socket type SOCK_PACKET to 1305 * implement this feature. 1306 * While this old implementation is kind of obsolete we need 1307 * to be compatible with older kernels for a while so we are 1308 * trying both methods with the newer method preferred. 1309 */ 1310 status = activate_new(handle); 1311 if (status < 0) { 1312 /* 1313 * Fatal error with the new way; just fail. 1314 * status has the error return; if it's PCAP_ERROR, 1315 * handle->errbuf has been set appropriately. 1316 */ 1317 goto fail; 1318 } 1319 if (status == 1) { 1320 /* 1321 * Success. 1322 * Try to use memory-mapped access. 1323 */ 1324 switch (activate_mmap(handle, &status)) { 1325 1326 case 1: 1327 /* 1328 * We succeeded. status has been 1329 * set to the status to return, 1330 * which might be 0, or might be 1331 * a PCAP_WARNING_ value. 1332 */ 1333 return status; 1334 1335 case 0: 1336 /* 1337 * Kernel doesn't support it - just continue 1338 * with non-memory-mapped access. 1339 */ 1340 break; 1341 1342 case -1: 1343 /* 1344 * We failed to set up to use it, or the kernel 1345 * supports it, but we failed to enable it. 1346 * status has been set to the error status to 1347 * return and, if it's PCAP_ERROR, handle->errbuf 1348 * contains the error message. 1349 */ 1350 goto fail; 1351 } 1352 } 1353 else if (status == 0) { 1354 /* Non-fatal error; try old way */ 1355 if ((status = activate_old(handle)) != 1) { 1356 /* 1357 * Both methods to open the packet socket failed. 1358 * Tidy up and report our failure (handle->errbuf 1359 * is expected to be set by the functions above). 1360 */ 1361 goto fail; 1362 } 1363 } 1364 1365 /* 1366 * We set up the socket, but not with memory-mapped access. 1367 */ 1368 status = 0; 1369 if (handle->opt.buffer_size != 0) { 1370 /* 1371 * Set the socket buffer size to the specified value. 1372 */ 1373 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, 1374 &handle->opt.buffer_size, 1375 sizeof(handle->opt.buffer_size)) == -1) { 1376 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1377 "SO_RCVBUF: %s", pcap_strerror(errno)); 1378 status = PCAP_ERROR; 1379 goto fail; 1380 } 1381 } 1382 1383 /* Allocate the buffer */ 1384 1385 handle->buffer = malloc(handle->bufsize + handle->offset); 1386 if (!handle->buffer) { 1387 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1388 "malloc: %s", pcap_strerror(errno)); 1389 status = PCAP_ERROR; 1390 goto fail; 1391 } 1392 1393 /* 1394 * "handle->fd" is a socket, so "select()" and "poll()" 1395 * should work on it. 1396 */ 1397 handle->selectable_fd = handle->fd; 1398 1399 return status; 1400 1401 fail: 1402 pcap_cleanup_linux(handle); 1403 return status; 1404 } 1405 1406 /* 1407 * Read at most max_packets from the capture stream and call the callback 1408 * for each of them. Returns the number of packets handled or -1 if an 1409 * error occured. 1410 */ 1411 static int 1412 pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) 1413 { 1414 /* 1415 * Currently, on Linux only one packet is delivered per read, 1416 * so we don't loop. 1417 */ 1418 return pcap_read_packet(handle, callback, user); 1419 } 1420 1421 /* 1422 * Read a packet from the socket calling the handler provided by 1423 * the user. Returns the number of packets received or -1 if an 1424 * error occured. 1425 */ 1426 static int 1427 pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata) 1428 { 1429 u_char *bp; 1430 int offset; 1431 #ifdef HAVE_PF_PACKET_SOCKETS 1432 struct sockaddr_ll from; 1433 struct sll_header *hdrp; 1434 #else 1435 struct sockaddr from; 1436 #endif 1437 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1438 struct iovec iov; 1439 struct msghdr msg; 1440 struct cmsghdr *cmsg; 1441 union { 1442 struct cmsghdr cmsg; 1443 char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))]; 1444 } cmsg_buf; 1445 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1446 socklen_t fromlen; 1447 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1448 int packet_len, caplen; 1449 struct pcap_pkthdr pcap_header; 1450 1451 #ifdef HAVE_PF_PACKET_SOCKETS 1452 /* 1453 * If this is a cooked device, leave extra room for a 1454 * fake packet header. 1455 */ 1456 if (handle->md.cooked) 1457 offset = SLL_HDR_LEN; 1458 else 1459 offset = 0; 1460 #else 1461 /* 1462 * This system doesn't have PF_PACKET sockets, so it doesn't 1463 * support cooked devices. 1464 */ 1465 offset = 0; 1466 #endif 1467 1468 /* 1469 * Receive a single packet from the kernel. 1470 * We ignore EINTR, as that might just be due to a signal 1471 * being delivered - if the signal should interrupt the 1472 * loop, the signal handler should call pcap_breakloop() 1473 * to set handle->break_loop (we ignore it on other 1474 * platforms as well). 1475 * We also ignore ENETDOWN, so that we can continue to 1476 * capture traffic if the interface goes down and comes 1477 * back up again; comments in the kernel indicate that 1478 * we'll just block waiting for packets if we try to 1479 * receive from a socket that delivered ENETDOWN, and, 1480 * if we're using a memory-mapped buffer, we won't even 1481 * get notified of "network down" events. 1482 */ 1483 bp = handle->buffer + handle->offset; 1484 1485 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1486 msg.msg_name = &from; 1487 msg.msg_namelen = sizeof(from); 1488 msg.msg_iov = &iov; 1489 msg.msg_iovlen = 1; 1490 msg.msg_control = &cmsg_buf; 1491 msg.msg_controllen = sizeof(cmsg_buf); 1492 msg.msg_flags = 0; 1493 1494 iov.iov_len = handle->bufsize - offset; 1495 iov.iov_base = bp + offset; 1496 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1497 1498 do { 1499 /* 1500 * Has "pcap_breakloop()" been called? 1501 */ 1502 if (handle->break_loop) { 1503 /* 1504 * Yes - clear the flag that indicates that it has, 1505 * and return PCAP_ERROR_BREAK as an indication that 1506 * we were told to break out of the loop. 1507 */ 1508 handle->break_loop = 0; 1509 return PCAP_ERROR_BREAK; 1510 } 1511 1512 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1513 packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC); 1514 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1515 fromlen = sizeof(from); 1516 packet_len = recvfrom( 1517 handle->fd, bp + offset, 1518 handle->bufsize - offset, MSG_TRUNC, 1519 (struct sockaddr *) &from, &fromlen); 1520 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1521 } while (packet_len == -1 && errno == EINTR); 1522 1523 /* Check if an error occured */ 1524 1525 if (packet_len == -1) { 1526 switch (errno) { 1527 1528 case EAGAIN: 1529 return 0; /* no packet there */ 1530 1531 case ENETDOWN: 1532 /* 1533 * The device on which we're capturing went away. 1534 * 1535 * XXX - we should really return 1536 * PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch() 1537 * etc. aren't defined to return that. 1538 */ 1539 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1540 "The interface went down"); 1541 return PCAP_ERROR; 1542 1543 default: 1544 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1545 "recvfrom: %s", pcap_strerror(errno)); 1546 return PCAP_ERROR; 1547 } 1548 } 1549 1550 #ifdef HAVE_PF_PACKET_SOCKETS 1551 if (!handle->md.sock_packet) { 1552 /* 1553 * Unfortunately, there is a window between socket() and 1554 * bind() where the kernel may queue packets from any 1555 * interface. If we're bound to a particular interface, 1556 * discard packets not from that interface. 1557 * 1558 * (If socket filters are supported, we could do the 1559 * same thing we do when changing the filter; however, 1560 * that won't handle packet sockets without socket 1561 * filter support, and it's a bit more complicated. 1562 * It would save some instructions per packet, however.) 1563 */ 1564 if (handle->md.ifindex != -1 && 1565 from.sll_ifindex != handle->md.ifindex) 1566 return 0; 1567 1568 /* 1569 * Do checks based on packet direction. 1570 * We can only do this if we're using PF_PACKET; the 1571 * address returned for SOCK_PACKET is a "sockaddr_pkt" 1572 * which lacks the relevant packet type information. 1573 */ 1574 if (from.sll_pkttype == PACKET_OUTGOING) { 1575 /* 1576 * Outgoing packet. 1577 * If this is from the loopback device, reject it; 1578 * we'll see the packet as an incoming packet as well, 1579 * and we don't want to see it twice. 1580 */ 1581 if (from.sll_ifindex == handle->md.lo_ifindex) 1582 return 0; 1583 1584 /* 1585 * If the user only wants incoming packets, reject it. 1586 */ 1587 if (handle->direction == PCAP_D_IN) 1588 return 0; 1589 } else { 1590 /* 1591 * Incoming packet. 1592 * If the user only wants outgoing packets, reject it. 1593 */ 1594 if (handle->direction == PCAP_D_OUT) 1595 return 0; 1596 } 1597 } 1598 #endif 1599 1600 #ifdef HAVE_PF_PACKET_SOCKETS 1601 /* 1602 * If this is a cooked device, fill in the fake packet header. 1603 */ 1604 if (handle->md.cooked) { 1605 /* 1606 * Add the length of the fake header to the length 1607 * of packet data we read. 1608 */ 1609 packet_len += SLL_HDR_LEN; 1610 1611 hdrp = (struct sll_header *)bp; 1612 hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype); 1613 hdrp->sll_hatype = htons(from.sll_hatype); 1614 hdrp->sll_halen = htons(from.sll_halen); 1615 memcpy(hdrp->sll_addr, from.sll_addr, 1616 (from.sll_halen > SLL_ADDRLEN) ? 1617 SLL_ADDRLEN : 1618 from.sll_halen); 1619 hdrp->sll_protocol = from.sll_protocol; 1620 } 1621 1622 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1623 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { 1624 struct tpacket_auxdata *aux; 1625 unsigned int len; 1626 struct vlan_tag *tag; 1627 1628 if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) || 1629 cmsg->cmsg_level != SOL_PACKET || 1630 cmsg->cmsg_type != PACKET_AUXDATA) 1631 continue; 1632 1633 aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg); 1634 if (aux->tp_vlan_tci == 0) 1635 continue; 1636 1637 len = packet_len > iov.iov_len ? iov.iov_len : packet_len; 1638 if (len < 2 * ETH_ALEN) 1639 break; 1640 1641 bp -= VLAN_TAG_LEN; 1642 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); 1643 1644 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); 1645 tag->vlan_tpid = htons(ETH_P_8021Q); 1646 tag->vlan_tci = htons(aux->tp_vlan_tci); 1647 1648 packet_len += VLAN_TAG_LEN; 1649 } 1650 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1651 #endif /* HAVE_PF_PACKET_SOCKETS */ 1652 1653 /* 1654 * XXX: According to the kernel source we should get the real 1655 * packet len if calling recvfrom with MSG_TRUNC set. It does 1656 * not seem to work here :(, but it is supported by this code 1657 * anyway. 1658 * To be honest the code RELIES on that feature so this is really 1659 * broken with 2.2.x kernels. 1660 * I spend a day to figure out what's going on and I found out 1661 * that the following is happening: 1662 * 1663 * The packet comes from a random interface and the packet_rcv 1664 * hook is called with a clone of the packet. That code inserts 1665 * the packet into the receive queue of the packet socket. 1666 * If a filter is attached to that socket that filter is run 1667 * first - and there lies the problem. The default filter always 1668 * cuts the packet at the snaplen: 1669 * 1670 * # tcpdump -d 1671 * (000) ret #68 1672 * 1673 * So the packet filter cuts down the packet. The recvfrom call 1674 * says "hey, it's only 68 bytes, it fits into the buffer" with 1675 * the result that we don't get the real packet length. This 1676 * is valid at least until kernel 2.2.17pre6. 1677 * 1678 * We currently handle this by making a copy of the filter 1679 * program, fixing all "ret" instructions with non-zero 1680 * operands to have an operand of 65535 so that the filter 1681 * doesn't truncate the packet, and supplying that modified 1682 * filter to the kernel. 1683 */ 1684 1685 caplen = packet_len; 1686 if (caplen > handle->snapshot) 1687 caplen = handle->snapshot; 1688 1689 /* Run the packet filter if not using kernel filter */ 1690 if (!handle->md.use_bpf && handle->fcode.bf_insns) { 1691 if (bpf_filter(handle->fcode.bf_insns, bp, 1692 packet_len, caplen) == 0) 1693 { 1694 /* rejected by filter */ 1695 return 0; 1696 } 1697 } 1698 1699 /* Fill in our own header data */ 1700 1701 if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) { 1702 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1703 "SIOCGSTAMP: %s", pcap_strerror(errno)); 1704 return PCAP_ERROR; 1705 } 1706 pcap_header.caplen = caplen; 1707 pcap_header.len = packet_len; 1708 1709 /* 1710 * Count the packet. 1711 * 1712 * Arguably, we should count them before we check the filter, 1713 * as on many other platforms "ps_recv" counts packets 1714 * handed to the filter rather than packets that passed 1715 * the filter, but if filtering is done in the kernel, we 1716 * can't get a count of packets that passed the filter, 1717 * and that would mean the meaning of "ps_recv" wouldn't 1718 * be the same on all Linux systems. 1719 * 1720 * XXX - it's not the same on all systems in any case; 1721 * ideally, we should have a "get the statistics" call 1722 * that supplies more counts and indicates which of them 1723 * it supplies, so that we supply a count of packets 1724 * handed to the filter only on platforms where that 1725 * information is available. 1726 * 1727 * We count them here even if we can get the packet count 1728 * from the kernel, as we can only determine at run time 1729 * whether we'll be able to get it from the kernel (if 1730 * HAVE_TPACKET_STATS isn't defined, we can't get it from 1731 * the kernel, but if it is defined, the library might 1732 * have been built with a 2.4 or later kernel, but we 1733 * might be running on a 2.2[.x] kernel without Alexey 1734 * Kuznetzov's turbopacket patches, and thus the kernel 1735 * might not be able to supply those statistics). We 1736 * could, I guess, try, when opening the socket, to get 1737 * the statistics, and if we can not increment the count 1738 * here, but it's not clear that always incrementing 1739 * the count is more expensive than always testing a flag 1740 * in memory. 1741 * 1742 * We keep the count in "md.packets_read", and use that for 1743 * "ps_recv" if we can't get the statistics from the kernel. 1744 * We do that because, if we *can* get the statistics from 1745 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop" 1746 * as running counts, as reading the statistics from the 1747 * kernel resets the kernel statistics, and if we directly 1748 * increment "md.stat.ps_recv" here, that means it will 1749 * count packets *twice* on systems where we can get kernel 1750 * statistics - once here, and once in pcap_stats_linux(). 1751 */ 1752 handle->md.packets_read++; 1753 1754 /* Call the user supplied callback function */ 1755 callback(userdata, &pcap_header, bp); 1756 1757 return 1; 1758 } 1759 1760 static int 1761 pcap_inject_linux(pcap_t *handle, const void *buf, size_t size) 1762 { 1763 int ret; 1764 1765 #ifdef HAVE_PF_PACKET_SOCKETS 1766 if (!handle->md.sock_packet) { 1767 /* PF_PACKET socket */ 1768 if (handle->md.ifindex == -1) { 1769 /* 1770 * We don't support sending on the "any" device. 1771 */ 1772 strlcpy(handle->errbuf, 1773 "Sending packets isn't supported on the \"any\" device", 1774 PCAP_ERRBUF_SIZE); 1775 return (-1); 1776 } 1777 1778 if (handle->md.cooked) { 1779 /* 1780 * We don't support sending on the "any" device. 1781 * 1782 * XXX - how do you send on a bound cooked-mode 1783 * socket? 1784 * Is a "sendto()" required there? 1785 */ 1786 strlcpy(handle->errbuf, 1787 "Sending packets isn't supported in cooked mode", 1788 PCAP_ERRBUF_SIZE); 1789 return (-1); 1790 } 1791 } 1792 #endif 1793 1794 ret = send(handle->fd, buf, size, 0); 1795 if (ret == -1) { 1796 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s", 1797 pcap_strerror(errno)); 1798 return (-1); 1799 } 1800 return (ret); 1801 } 1802 1803 /* 1804 * Get the statistics for the given packet capture handle. 1805 * Reports the number of dropped packets iff the kernel supports 1806 * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later 1807 * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket 1808 * patches); otherwise, that information isn't available, and we lie 1809 * and report 0 as the count of dropped packets. 1810 */ 1811 static int 1812 pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) 1813 { 1814 #ifdef HAVE_TPACKET_STATS 1815 struct tpacket_stats kstats; 1816 socklen_t len = sizeof (struct tpacket_stats); 1817 #endif 1818 1819 long if_dropped = 0; 1820 1821 /* 1822 * To fill in ps_ifdrop, we parse /proc/net/dev for the number 1823 */ 1824 if (handle->opt.promisc) 1825 { 1826 if_dropped = handle->md.proc_dropped; 1827 handle->md.proc_dropped = linux_if_drops(handle->md.device); 1828 handle->md.stat.ps_ifdrop += (handle->md.proc_dropped - if_dropped); 1829 } 1830 1831 #ifdef HAVE_TPACKET_STATS 1832 /* 1833 * Try to get the packet counts from the kernel. 1834 */ 1835 if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, 1836 &kstats, &len) > -1) { 1837 /* 1838 * On systems where the PACKET_STATISTICS "getsockopt()" 1839 * argument is supported on PF_PACKET sockets: 1840 * 1841 * "ps_recv" counts only packets that *passed* the 1842 * filter, not packets that didn't pass the filter. 1843 * This includes packets later dropped because we 1844 * ran out of buffer space. 1845 * 1846 * "ps_drop" counts packets dropped because we ran 1847 * out of buffer space. It doesn't count packets 1848 * dropped by the interface driver. It counts only 1849 * packets that passed the filter. 1850 * 1851 * See above for ps_ifdrop. 1852 * 1853 * Both statistics include packets not yet read from 1854 * the kernel by libpcap, and thus not yet seen by 1855 * the application. 1856 * 1857 * In "linux/net/packet/af_packet.c", at least in the 1858 * 2.4.9 kernel, "tp_packets" is incremented for every 1859 * packet that passes the packet filter *and* is 1860 * successfully queued on the socket; "tp_drops" is 1861 * incremented for every packet dropped because there's 1862 * not enough free space in the socket buffer. 1863 * 1864 * When the statistics are returned for a PACKET_STATISTICS 1865 * "getsockopt()" call, "tp_drops" is added to "tp_packets", 1866 * so that "tp_packets" counts all packets handed to 1867 * the PF_PACKET socket, including packets dropped because 1868 * there wasn't room on the socket buffer - but not 1869 * including packets that didn't pass the filter. 1870 * 1871 * In the BSD BPF, the count of received packets is 1872 * incremented for every packet handed to BPF, regardless 1873 * of whether it passed the filter. 1874 * 1875 * We can't make "pcap_stats()" work the same on both 1876 * platforms, but the best approximation is to return 1877 * "tp_packets" as the count of packets and "tp_drops" 1878 * as the count of drops. 1879 * 1880 * Keep a running total because each call to 1881 * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, .... 1882 * resets the counters to zero. 1883 */ 1884 handle->md.stat.ps_recv += kstats.tp_packets; 1885 handle->md.stat.ps_drop += kstats.tp_drops; 1886 *stats = handle->md.stat; 1887 return 0; 1888 } 1889 else 1890 { 1891 /* 1892 * If the error was EOPNOTSUPP, fall through, so that 1893 * if you build the library on a system with 1894 * "struct tpacket_stats" and run it on a system 1895 * that doesn't, it works as it does if the library 1896 * is built on a system without "struct tpacket_stats". 1897 */ 1898 if (errno != EOPNOTSUPP) { 1899 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1900 "pcap_stats: %s", pcap_strerror(errno)); 1901 return -1; 1902 } 1903 } 1904 #endif 1905 /* 1906 * On systems where the PACKET_STATISTICS "getsockopt()" argument 1907 * is not supported on PF_PACKET sockets: 1908 * 1909 * "ps_recv" counts only packets that *passed* the filter, 1910 * not packets that didn't pass the filter. It does not 1911 * count packets dropped because we ran out of buffer 1912 * space. 1913 * 1914 * "ps_drop" is not supported. 1915 * 1916 * "ps_ifdrop" is supported. It will return the number 1917 * of drops the interface reports in /proc/net/dev, 1918 * if that is available. 1919 * 1920 * "ps_recv" doesn't include packets not yet read from 1921 * the kernel by libpcap. 1922 * 1923 * We maintain the count of packets processed by libpcap in 1924 * "md.packets_read", for reasons described in the comment 1925 * at the end of pcap_read_packet(). We have no idea how many 1926 * packets were dropped by the kernel buffers -- but we know 1927 * how many the interface dropped, so we can return that. 1928 */ 1929 1930 stats->ps_recv = handle->md.packets_read; 1931 stats->ps_drop = 0; 1932 stats->ps_ifdrop = handle->md.stat.ps_ifdrop; 1933 return 0; 1934 } 1935 1936 /* 1937 * Get from "/sys/class/net" all interfaces listed there; if they're 1938 * already in the list of interfaces we have, that won't add another 1939 * instance, but if they're not, that'll add them. 1940 * 1941 * We don't bother getting any addresses for them; it appears you can't 1942 * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and, 1943 * although some other types of addresses can be fetched with SIOCGIFADDR, 1944 * we don't bother with them for now. 1945 * 1946 * We also don't fail if we couldn't open "/sys/class/net"; we just leave 1947 * the list of interfaces as is, and return 0, so that we can try 1948 * scanning /proc/net/dev. 1949 */ 1950 static int 1951 scan_sys_class_net(pcap_if_t **devlistp, char *errbuf) 1952 { 1953 DIR *sys_class_net_d; 1954 int fd; 1955 struct dirent *ent; 1956 char *p; 1957 char name[512]; /* XXX - pick a size */ 1958 char *q, *saveq; 1959 struct ifreq ifrflags; 1960 int ret = 1; 1961 1962 sys_class_net_d = opendir("/sys/class/net"); 1963 if (sys_class_net_d == NULL) { 1964 /* 1965 * Don't fail if it doesn't exist at all. 1966 */ 1967 if (errno == ENOENT) 1968 return (0); 1969 1970 /* 1971 * Fail if we got some other error. 1972 */ 1973 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 1974 "Can't open /sys/class/net: %s", pcap_strerror(errno)); 1975 return (-1); 1976 } 1977 1978 /* 1979 * Create a socket from which to fetch interface information. 1980 */ 1981 fd = socket(AF_INET, SOCK_DGRAM, 0); 1982 if (fd < 0) { 1983 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 1984 "socket: %s", pcap_strerror(errno)); 1985 (void)closedir(sys_class_net_d); 1986 return (-1); 1987 } 1988 1989 for (;;) { 1990 errno = 0; 1991 ent = readdir(sys_class_net_d); 1992 if (ent == NULL) { 1993 /* 1994 * Error or EOF; if errno != 0, it's an error. 1995 */ 1996 break; 1997 } 1998 1999 /* 2000 * Ignore directories (".", "..", and any subdirectories). 2001 */ 2002 if (ent->d_type == DT_DIR) 2003 continue; 2004 2005 /* 2006 * Get the interface name. 2007 */ 2008 p = &ent->d_name[0]; 2009 q = &name[0]; 2010 while (*p != '\0' && isascii(*p) && !isspace(*p)) { 2011 if (*p == ':') { 2012 /* 2013 * This could be the separator between a 2014 * name and an alias number, or it could be 2015 * the separator between a name with no 2016 * alias number and the next field. 2017 * 2018 * If there's a colon after digits, it 2019 * separates the name and the alias number, 2020 * otherwise it separates the name and the 2021 * next field. 2022 */ 2023 saveq = q; 2024 while (isascii(*p) && isdigit(*p)) 2025 *q++ = *p++; 2026 if (*p != ':') { 2027 /* 2028 * That was the next field, 2029 * not the alias number. 2030 */ 2031 q = saveq; 2032 } 2033 break; 2034 } else 2035 *q++ = *p++; 2036 } 2037 *q = '\0'; 2038 2039 /* 2040 * Get the flags for this interface, and skip it if 2041 * it's not up. 2042 */ 2043 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); 2044 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { 2045 if (errno == ENXIO || errno == ENODEV) 2046 continue; 2047 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2048 "SIOCGIFFLAGS: %.*s: %s", 2049 (int)sizeof(ifrflags.ifr_name), 2050 ifrflags.ifr_name, 2051 pcap_strerror(errno)); 2052 ret = -1; 2053 break; 2054 } 2055 if (!(ifrflags.ifr_flags & IFF_UP)) 2056 continue; 2057 2058 /* 2059 * Add an entry for this interface, with no addresses. 2060 */ 2061 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL, 2062 errbuf) == -1) { 2063 /* 2064 * Failure. 2065 */ 2066 ret = -1; 2067 break; 2068 } 2069 } 2070 if (ret != -1) { 2071 /* 2072 * Well, we didn't fail for any other reason; did we 2073 * fail due to an error reading the directory? 2074 */ 2075 if (errno != 0) { 2076 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2077 "Error reading /sys/class/net: %s", 2078 pcap_strerror(errno)); 2079 ret = -1; 2080 } 2081 } 2082 2083 (void)close(fd); 2084 (void)closedir(sys_class_net_d); 2085 return (ret); 2086 } 2087 2088 /* 2089 * Get from "/proc/net/dev" all interfaces listed there; if they're 2090 * already in the list of interfaces we have, that won't add another 2091 * instance, but if they're not, that'll add them. 2092 * 2093 * See comments from scan_sys_class_net(). 2094 */ 2095 static int 2096 scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf) 2097 { 2098 FILE *proc_net_f; 2099 int fd; 2100 char linebuf[512]; 2101 int linenum; 2102 char *p; 2103 char name[512]; /* XXX - pick a size */ 2104 char *q, *saveq; 2105 struct ifreq ifrflags; 2106 int ret = 0; 2107 2108 proc_net_f = fopen("/proc/net/dev", "r"); 2109 if (proc_net_f == NULL) { 2110 /* 2111 * Don't fail if it doesn't exist at all. 2112 */ 2113 if (errno == ENOENT) 2114 return (0); 2115 2116 /* 2117 * Fail if we got some other error. 2118 */ 2119 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2120 "Can't open /proc/net/dev: %s", pcap_strerror(errno)); 2121 return (-1); 2122 } 2123 2124 /* 2125 * Create a socket from which to fetch interface information. 2126 */ 2127 fd = socket(AF_INET, SOCK_DGRAM, 0); 2128 if (fd < 0) { 2129 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2130 "socket: %s", pcap_strerror(errno)); 2131 (void)fclose(proc_net_f); 2132 return (-1); 2133 } 2134 2135 for (linenum = 1; 2136 fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) { 2137 /* 2138 * Skip the first two lines - they're headers. 2139 */ 2140 if (linenum <= 2) 2141 continue; 2142 2143 p = &linebuf[0]; 2144 2145 /* 2146 * Skip leading white space. 2147 */ 2148 while (*p != '\0' && isascii(*p) && isspace(*p)) 2149 p++; 2150 if (*p == '\0' || *p == '\n') 2151 continue; /* blank line */ 2152 2153 /* 2154 * Get the interface name. 2155 */ 2156 q = &name[0]; 2157 while (*p != '\0' && isascii(*p) && !isspace(*p)) { 2158 if (*p == ':') { 2159 /* 2160 * This could be the separator between a 2161 * name and an alias number, or it could be 2162 * the separator between a name with no 2163 * alias number and the next field. 2164 * 2165 * If there's a colon after digits, it 2166 * separates the name and the alias number, 2167 * otherwise it separates the name and the 2168 * next field. 2169 */ 2170 saveq = q; 2171 while (isascii(*p) && isdigit(*p)) 2172 *q++ = *p++; 2173 if (*p != ':') { 2174 /* 2175 * That was the next field, 2176 * not the alias number. 2177 */ 2178 q = saveq; 2179 } 2180 break; 2181 } else 2182 *q++ = *p++; 2183 } 2184 *q = '\0'; 2185 2186 /* 2187 * Get the flags for this interface, and skip it if 2188 * it's not up. 2189 */ 2190 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); 2191 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { 2192 if (errno == ENXIO) 2193 continue; 2194 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2195 "SIOCGIFFLAGS: %.*s: %s", 2196 (int)sizeof(ifrflags.ifr_name), 2197 ifrflags.ifr_name, 2198 pcap_strerror(errno)); 2199 ret = -1; 2200 break; 2201 } 2202 if (!(ifrflags.ifr_flags & IFF_UP)) 2203 continue; 2204 2205 /* 2206 * Add an entry for this interface, with no addresses. 2207 */ 2208 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL, 2209 errbuf) == -1) { 2210 /* 2211 * Failure. 2212 */ 2213 ret = -1; 2214 break; 2215 } 2216 } 2217 if (ret != -1) { 2218 /* 2219 * Well, we didn't fail for any other reason; did we 2220 * fail due to an error reading the file? 2221 */ 2222 if (ferror(proc_net_f)) { 2223 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2224 "Error reading /proc/net/dev: %s", 2225 pcap_strerror(errno)); 2226 ret = -1; 2227 } 2228 } 2229 2230 (void)close(fd); 2231 (void)fclose(proc_net_f); 2232 return (ret); 2233 } 2234 2235 /* 2236 * Description string for the "any" device. 2237 */ 2238 static const char any_descr[] = "Pseudo-device that captures on all interfaces"; 2239 2240 int 2241 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) 2242 { 2243 int ret; 2244 2245 /* 2246 * Read "/sys/class/net", and add to the list of interfaces all 2247 * interfaces listed there that we don't already have, because, 2248 * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses, 2249 * and even getifaddrs() won't return information about 2250 * interfaces with no addresses, so you need to read "/sys/class/net" 2251 * to get the names of the rest of the interfaces. 2252 */ 2253 ret = scan_sys_class_net(alldevsp, errbuf); 2254 if (ret == -1) 2255 return (-1); /* failed */ 2256 if (ret == 0) { 2257 /* 2258 * No /sys/class/net; try reading /proc/net/dev instead. 2259 */ 2260 if (scan_proc_net_dev(alldevsp, errbuf) == -1) 2261 return (-1); 2262 } 2263 2264 /* 2265 * Add the "any" device. 2266 */ 2267 if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0) 2268 return (-1); 2269 2270 #ifdef HAVE_DAG_API 2271 /* 2272 * Add DAG devices. 2273 */ 2274 if (dag_platform_finddevs(alldevsp, errbuf) < 0) 2275 return (-1); 2276 #endif /* HAVE_DAG_API */ 2277 2278 #ifdef HAVE_SEPTEL_API 2279 /* 2280 * Add Septel devices. 2281 */ 2282 if (septel_platform_finddevs(alldevsp, errbuf) < 0) 2283 return (-1); 2284 #endif /* HAVE_SEPTEL_API */ 2285 2286 #ifdef HAVE_SNF_API 2287 if (snf_platform_finddevs(alldevsp, errbuf) < 0) 2288 return (-1); 2289 #endif /* HAVE_SNF_API */ 2290 2291 #ifdef PCAP_SUPPORT_BT 2292 /* 2293 * Add Bluetooth devices. 2294 */ 2295 if (bt_platform_finddevs(alldevsp, errbuf) < 0) 2296 return (-1); 2297 #endif 2298 2299 #ifdef PCAP_SUPPORT_USB 2300 /* 2301 * Add USB devices. 2302 */ 2303 if (usb_platform_finddevs(alldevsp, errbuf) < 0) 2304 return (-1); 2305 #endif 2306 2307 #ifdef PCAP_SUPPORT_NETFILTER 2308 /* 2309 * Add netfilter devices. 2310 */ 2311 if (netfilter_platform_finddevs(alldevsp, errbuf) < 0) 2312 return (-1); 2313 #endif 2314 2315 #if PCAP_SUPPORT_CANUSB 2316 if (canusb_platform_finddevs(alldevsp, errbuf) < 0) 2317 return (-1); 2318 #endif 2319 2320 return (0); 2321 } 2322 2323 /* 2324 * Attach the given BPF code to the packet capture device. 2325 */ 2326 static int 2327 pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, 2328 int is_mmapped) 2329 { 2330 #ifdef SO_ATTACH_FILTER 2331 struct sock_fprog fcode; 2332 int can_filter_in_kernel; 2333 int err = 0; 2334 #endif 2335 2336 if (!handle) 2337 return -1; 2338 if (!filter) { 2339 strncpy(handle->errbuf, "setfilter: No filter specified", 2340 PCAP_ERRBUF_SIZE); 2341 return -1; 2342 } 2343 2344 /* Make our private copy of the filter */ 2345 2346 if (install_bpf_program(handle, filter) < 0) 2347 /* install_bpf_program() filled in errbuf */ 2348 return -1; 2349 2350 /* 2351 * Run user level packet filter by default. Will be overriden if 2352 * installing a kernel filter succeeds. 2353 */ 2354 handle->md.use_bpf = 0; 2355 2356 /* Install kernel level filter if possible */ 2357 2358 #ifdef SO_ATTACH_FILTER 2359 #ifdef USHRT_MAX 2360 if (handle->fcode.bf_len > USHRT_MAX) { 2361 /* 2362 * fcode.len is an unsigned short for current kernel. 2363 * I have yet to see BPF-Code with that much 2364 * instructions but still it is possible. So for the 2365 * sake of correctness I added this check. 2366 */ 2367 fprintf(stderr, "Warning: Filter too complex for kernel\n"); 2368 fcode.len = 0; 2369 fcode.filter = NULL; 2370 can_filter_in_kernel = 0; 2371 } else 2372 #endif /* USHRT_MAX */ 2373 { 2374 /* 2375 * Oh joy, the Linux kernel uses struct sock_fprog instead 2376 * of struct bpf_program and of course the length field is 2377 * of different size. Pointed out by Sebastian 2378 * 2379 * Oh, and we also need to fix it up so that all "ret" 2380 * instructions with non-zero operands have 65535 as the 2381 * operand if we're not capturing in memory-mapped modee, 2382 * and so that, if we're in cooked mode, all memory-reference 2383 * instructions use special magic offsets in references to 2384 * the link-layer header and assume that the link-layer 2385 * payload begins at 0; "fix_program()" will do that. 2386 */ 2387 switch (fix_program(handle, &fcode, is_mmapped)) { 2388 2389 case -1: 2390 default: 2391 /* 2392 * Fatal error; just quit. 2393 * (The "default" case shouldn't happen; we 2394 * return -1 for that reason.) 2395 */ 2396 return -1; 2397 2398 case 0: 2399 /* 2400 * The program performed checks that we can't make 2401 * work in the kernel. 2402 */ 2403 can_filter_in_kernel = 0; 2404 break; 2405 2406 case 1: 2407 /* 2408 * We have a filter that'll work in the kernel. 2409 */ 2410 can_filter_in_kernel = 1; 2411 break; 2412 } 2413 } 2414 2415 /* 2416 * NOTE: at this point, we've set both the "len" and "filter" 2417 * fields of "fcode". As of the 2.6.32.4 kernel, at least, 2418 * those are the only members of the "sock_fprog" structure, 2419 * so we initialize every member of that structure. 2420 * 2421 * If there is anything in "fcode" that is not initialized, 2422 * it is either a field added in a later kernel, or it's 2423 * padding. 2424 * 2425 * If a new field is added, this code needs to be updated 2426 * to set it correctly. 2427 * 2428 * If there are no other fields, then: 2429 * 2430 * if the Linux kernel looks at the padding, it's 2431 * buggy; 2432 * 2433 * if the Linux kernel doesn't look at the padding, 2434 * then if some tool complains that we're passing 2435 * uninitialized data to the kernel, then the tool 2436 * is buggy and needs to understand that it's just 2437 * padding. 2438 */ 2439 if (can_filter_in_kernel) { 2440 if ((err = set_kernel_filter(handle, &fcode)) == 0) 2441 { 2442 /* Installation succeded - using kernel filter. */ 2443 handle->md.use_bpf = 1; 2444 } 2445 else if (err == -1) /* Non-fatal error */ 2446 { 2447 /* 2448 * Print a warning if we weren't able to install 2449 * the filter for a reason other than "this kernel 2450 * isn't configured to support socket filters. 2451 */ 2452 if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) { 2453 fprintf(stderr, 2454 "Warning: Kernel filter failed: %s\n", 2455 pcap_strerror(errno)); 2456 } 2457 } 2458 } 2459 2460 /* 2461 * If we're not using the kernel filter, get rid of any kernel 2462 * filter that might've been there before, e.g. because the 2463 * previous filter could work in the kernel, or because some other 2464 * code attached a filter to the socket by some means other than 2465 * calling "pcap_setfilter()". Otherwise, the kernel filter may 2466 * filter out packets that would pass the new userland filter. 2467 */ 2468 if (!handle->md.use_bpf) 2469 reset_kernel_filter(handle); 2470 2471 /* 2472 * Free up the copy of the filter that was made by "fix_program()". 2473 */ 2474 if (fcode.filter != NULL) 2475 free(fcode.filter); 2476 2477 if (err == -2) 2478 /* Fatal error */ 2479 return -1; 2480 #endif /* SO_ATTACH_FILTER */ 2481 2482 return 0; 2483 } 2484 2485 static int 2486 pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) 2487 { 2488 return pcap_setfilter_linux_common(handle, filter, 0); 2489 } 2490 2491 2492 /* 2493 * Set direction flag: Which packets do we accept on a forwarding 2494 * single device? IN, OUT or both? 2495 */ 2496 static int 2497 pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d) 2498 { 2499 #ifdef HAVE_PF_PACKET_SOCKETS 2500 if (!handle->md.sock_packet) { 2501 handle->direction = d; 2502 return 0; 2503 } 2504 #endif 2505 /* 2506 * We're not using PF_PACKET sockets, so we can't determine 2507 * the direction of the packet. 2508 */ 2509 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 2510 "Setting direction is not supported on SOCK_PACKET sockets"); 2511 return -1; 2512 } 2513 2514 #ifdef HAVE_PF_PACKET_SOCKETS 2515 /* 2516 * Map the PACKET_ value to a LINUX_SLL_ value; we 2517 * want the same numerical value to be used in 2518 * the link-layer header even if the numerical values 2519 * for the PACKET_ #defines change, so that programs 2520 * that look at the packet type field will always be 2521 * able to handle DLT_LINUX_SLL captures. 2522 */ 2523 static short int 2524 map_packet_type_to_sll_type(short int sll_pkttype) 2525 { 2526 switch (sll_pkttype) { 2527 2528 case PACKET_HOST: 2529 return htons(LINUX_SLL_HOST); 2530 2531 case PACKET_BROADCAST: 2532 return htons(LINUX_SLL_BROADCAST); 2533 2534 case PACKET_MULTICAST: 2535 return htons(LINUX_SLL_MULTICAST); 2536 2537 case PACKET_OTHERHOST: 2538 return htons(LINUX_SLL_OTHERHOST); 2539 2540 case PACKET_OUTGOING: 2541 return htons(LINUX_SLL_OUTGOING); 2542 2543 default: 2544 return -1; 2545 } 2546 } 2547 #endif 2548 2549 /* 2550 * Linux uses the ARP hardware type to identify the type of an 2551 * interface. pcap uses the DLT_xxx constants for this. This 2552 * function takes a pointer to a "pcap_t", and an ARPHRD_xxx 2553 * constant, as arguments, and sets "handle->linktype" to the 2554 * appropriate DLT_XXX constant and sets "handle->offset" to 2555 * the appropriate value (to make "handle->offset" plus link-layer 2556 * header length be a multiple of 4, so that the link-layer payload 2557 * will be aligned on a 4-byte boundary when capturing packets). 2558 * (If the offset isn't set here, it'll be 0; add code as appropriate 2559 * for cases where it shouldn't be 0.) 2560 * 2561 * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture 2562 * in cooked mode; otherwise, we can't use cooked mode, so we have 2563 * to pick some type that works in raw mode, or fail. 2564 * 2565 * Sets the link type to -1 if unable to map the type. 2566 */ 2567 static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok) 2568 { 2569 switch (arptype) { 2570 2571 case ARPHRD_ETHER: 2572 /* 2573 * This is (presumably) a real Ethernet capture; give it a 2574 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so 2575 * that an application can let you choose it, in case you're 2576 * capturing DOCSIS traffic that a Cisco Cable Modem 2577 * Termination System is putting out onto an Ethernet (it 2578 * doesn't put an Ethernet header onto the wire, it puts raw 2579 * DOCSIS frames out on the wire inside the low-level 2580 * Ethernet framing). 2581 * 2582 * XXX - are there any sorts of "fake Ethernet" that have 2583 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as 2584 * a Cisco CMTS won't put traffic onto it or get traffic 2585 * bridged onto it? ISDN is handled in "activate_new()", 2586 * as we fall back on cooked mode there; are there any 2587 * others? 2588 */ 2589 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 2590 /* 2591 * If that fails, just leave the list empty. 2592 */ 2593 if (handle->dlt_list != NULL) { 2594 handle->dlt_list[0] = DLT_EN10MB; 2595 handle->dlt_list[1] = DLT_DOCSIS; 2596 handle->dlt_count = 2; 2597 } 2598 /* FALLTHROUGH */ 2599 2600 case ARPHRD_METRICOM: 2601 case ARPHRD_LOOPBACK: 2602 handle->linktype = DLT_EN10MB; 2603 handle->offset = 2; 2604 break; 2605 2606 case ARPHRD_EETHER: 2607 handle->linktype = DLT_EN3MB; 2608 break; 2609 2610 case ARPHRD_AX25: 2611 handle->linktype = DLT_AX25_KISS; 2612 break; 2613 2614 case ARPHRD_PRONET: 2615 handle->linktype = DLT_PRONET; 2616 break; 2617 2618 case ARPHRD_CHAOS: 2619 handle->linktype = DLT_CHAOS; 2620 break; 2621 #ifndef ARPHRD_CAN 2622 #define ARPHRD_CAN 280 2623 #endif 2624 case ARPHRD_CAN: 2625 handle->linktype = DLT_CAN_SOCKETCAN; 2626 break; 2627 2628 #ifndef ARPHRD_IEEE802_TR 2629 #define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ 2630 #endif 2631 case ARPHRD_IEEE802_TR: 2632 case ARPHRD_IEEE802: 2633 handle->linktype = DLT_IEEE802; 2634 handle->offset = 2; 2635 break; 2636 2637 case ARPHRD_ARCNET: 2638 handle->linktype = DLT_ARCNET_LINUX; 2639 break; 2640 2641 #ifndef ARPHRD_FDDI /* From Linux 2.2.13 */ 2642 #define ARPHRD_FDDI 774 2643 #endif 2644 case ARPHRD_FDDI: 2645 handle->linktype = DLT_FDDI; 2646 handle->offset = 3; 2647 break; 2648 2649 #ifndef ARPHRD_ATM /* FIXME: How to #include this? */ 2650 #define ARPHRD_ATM 19 2651 #endif 2652 case ARPHRD_ATM: 2653 /* 2654 * The Classical IP implementation in ATM for Linux 2655 * supports both what RFC 1483 calls "LLC Encapsulation", 2656 * in which each packet has an LLC header, possibly 2657 * with a SNAP header as well, prepended to it, and 2658 * what RFC 1483 calls "VC Based Multiplexing", in which 2659 * different virtual circuits carry different network 2660 * layer protocols, and no header is prepended to packets. 2661 * 2662 * They both have an ARPHRD_ type of ARPHRD_ATM, so 2663 * you can't use the ARPHRD_ type to find out whether 2664 * captured packets will have an LLC header, and, 2665 * while there's a socket ioctl to *set* the encapsulation 2666 * type, there's no ioctl to *get* the encapsulation type. 2667 * 2668 * This means that 2669 * 2670 * programs that dissect Linux Classical IP frames 2671 * would have to check for an LLC header and, 2672 * depending on whether they see one or not, dissect 2673 * the frame as LLC-encapsulated or as raw IP (I 2674 * don't know whether there's any traffic other than 2675 * IP that would show up on the socket, or whether 2676 * there's any support for IPv6 in the Linux 2677 * Classical IP code); 2678 * 2679 * filter expressions would have to compile into 2680 * code that checks for an LLC header and does 2681 * the right thing. 2682 * 2683 * Both of those are a nuisance - and, at least on systems 2684 * that support PF_PACKET sockets, we don't have to put 2685 * up with those nuisances; instead, we can just capture 2686 * in cooked mode. That's what we'll do, if we can. 2687 * Otherwise, we'll just fail. 2688 */ 2689 if (cooked_ok) 2690 handle->linktype = DLT_LINUX_SLL; 2691 else 2692 handle->linktype = -1; 2693 break; 2694 2695 #ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */ 2696 #define ARPHRD_IEEE80211 801 2697 #endif 2698 case ARPHRD_IEEE80211: 2699 handle->linktype = DLT_IEEE802_11; 2700 break; 2701 2702 #ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */ 2703 #define ARPHRD_IEEE80211_PRISM 802 2704 #endif 2705 case ARPHRD_IEEE80211_PRISM: 2706 handle->linktype = DLT_PRISM_HEADER; 2707 break; 2708 2709 #ifndef ARPHRD_IEEE80211_RADIOTAP /* new */ 2710 #define ARPHRD_IEEE80211_RADIOTAP 803 2711 #endif 2712 case ARPHRD_IEEE80211_RADIOTAP: 2713 handle->linktype = DLT_IEEE802_11_RADIO; 2714 break; 2715 2716 case ARPHRD_PPP: 2717 /* 2718 * Some PPP code in the kernel supplies no link-layer 2719 * header whatsoever to PF_PACKET sockets; other PPP 2720 * code supplies PPP link-layer headers ("syncppp.c"); 2721 * some PPP code might supply random link-layer 2722 * headers (PPP over ISDN - there's code in Ethereal, 2723 * for example, to cope with PPP-over-ISDN captures 2724 * with which the Ethereal developers have had to cope, 2725 * heuristically trying to determine which of the 2726 * oddball link-layer headers particular packets have). 2727 * 2728 * As such, we just punt, and run all PPP interfaces 2729 * in cooked mode, if we can; otherwise, we just treat 2730 * it as DLT_RAW, for now - if somebody needs to capture, 2731 * on a 2.0[.x] kernel, on PPP devices that supply a 2732 * link-layer header, they'll have to add code here to 2733 * map to the appropriate DLT_ type (possibly adding a 2734 * new DLT_ type, if necessary). 2735 */ 2736 if (cooked_ok) 2737 handle->linktype = DLT_LINUX_SLL; 2738 else { 2739 /* 2740 * XXX - handle ISDN types here? We can't fall 2741 * back on cooked sockets, so we'd have to 2742 * figure out from the device name what type of 2743 * link-layer encapsulation it's using, and map 2744 * that to an appropriate DLT_ value, meaning 2745 * we'd map "isdnN" devices to DLT_RAW (they 2746 * supply raw IP packets with no link-layer 2747 * header) and "isdY" devices to a new DLT_I4L_IP 2748 * type that has only an Ethernet packet type as 2749 * a link-layer header. 2750 * 2751 * But sometimes we seem to get random crap 2752 * in the link-layer header when capturing on 2753 * ISDN devices.... 2754 */ 2755 handle->linktype = DLT_RAW; 2756 } 2757 break; 2758 2759 #ifndef ARPHRD_CISCO 2760 #define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */ 2761 #endif 2762 case ARPHRD_CISCO: 2763 handle->linktype = DLT_C_HDLC; 2764 break; 2765 2766 /* Not sure if this is correct for all tunnels, but it 2767 * works for CIPE */ 2768 case ARPHRD_TUNNEL: 2769 #ifndef ARPHRD_SIT 2770 #define ARPHRD_SIT 776 /* From Linux 2.2.13 */ 2771 #endif 2772 case ARPHRD_SIT: 2773 case ARPHRD_CSLIP: 2774 case ARPHRD_SLIP6: 2775 case ARPHRD_CSLIP6: 2776 case ARPHRD_ADAPT: 2777 case ARPHRD_SLIP: 2778 #ifndef ARPHRD_RAWHDLC 2779 #define ARPHRD_RAWHDLC 518 2780 #endif 2781 case ARPHRD_RAWHDLC: 2782 #ifndef ARPHRD_DLCI 2783 #define ARPHRD_DLCI 15 2784 #endif 2785 case ARPHRD_DLCI: 2786 /* 2787 * XXX - should some of those be mapped to DLT_LINUX_SLL 2788 * instead? Should we just map all of them to DLT_LINUX_SLL? 2789 */ 2790 handle->linktype = DLT_RAW; 2791 break; 2792 2793 #ifndef ARPHRD_FRAD 2794 #define ARPHRD_FRAD 770 2795 #endif 2796 case ARPHRD_FRAD: 2797 handle->linktype = DLT_FRELAY; 2798 break; 2799 2800 case ARPHRD_LOCALTLK: 2801 handle->linktype = DLT_LTALK; 2802 break; 2803 2804 #ifndef ARPHRD_FCPP 2805 #define ARPHRD_FCPP 784 2806 #endif 2807 case ARPHRD_FCPP: 2808 #ifndef ARPHRD_FCAL 2809 #define ARPHRD_FCAL 785 2810 #endif 2811 case ARPHRD_FCAL: 2812 #ifndef ARPHRD_FCPL 2813 #define ARPHRD_FCPL 786 2814 #endif 2815 case ARPHRD_FCPL: 2816 #ifndef ARPHRD_FCFABRIC 2817 #define ARPHRD_FCFABRIC 787 2818 #endif 2819 case ARPHRD_FCFABRIC: 2820 /* 2821 * We assume that those all mean RFC 2625 IP-over- 2822 * Fibre Channel, with the RFC 2625 header at 2823 * the beginning of the packet. 2824 */ 2825 handle->linktype = DLT_IP_OVER_FC; 2826 break; 2827 2828 #ifndef ARPHRD_IRDA 2829 #define ARPHRD_IRDA 783 2830 #endif 2831 case ARPHRD_IRDA: 2832 /* Don't expect IP packet out of this interfaces... */ 2833 handle->linktype = DLT_LINUX_IRDA; 2834 /* We need to save packet direction for IrDA decoding, 2835 * so let's use "Linux-cooked" mode. Jean II */ 2836 //handle->md.cooked = 1; 2837 break; 2838 2839 /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation 2840 * is needed, please report it to <daniele@orlandi.com> */ 2841 #ifndef ARPHRD_LAPD 2842 #define ARPHRD_LAPD 8445 2843 #endif 2844 case ARPHRD_LAPD: 2845 /* Don't expect IP packet out of this interfaces... */ 2846 handle->linktype = DLT_LINUX_LAPD; 2847 break; 2848 2849 #ifndef ARPHRD_NONE 2850 #define ARPHRD_NONE 0xFFFE 2851 #endif 2852 case ARPHRD_NONE: 2853 /* 2854 * No link-layer header; packets are just IP 2855 * packets, so use DLT_RAW. 2856 */ 2857 handle->linktype = DLT_RAW; 2858 break; 2859 2860 #ifndef ARPHRD_IEEE802154 2861 #define ARPHRD_IEEE802154 804 2862 #endif 2863 case ARPHRD_IEEE802154: 2864 handle->linktype = DLT_IEEE802_15_4_NOFCS; 2865 break; 2866 2867 default: 2868 handle->linktype = -1; 2869 break; 2870 } 2871 } 2872 2873 /* ===== Functions to interface to the newer kernels ================== */ 2874 2875 /* 2876 * Try to open a packet socket using the new kernel PF_PACKET interface. 2877 * Returns 1 on success, 0 on an error that means the new interface isn't 2878 * present (so the old SOCK_PACKET interface should be tried), and a 2879 * PCAP_ERROR_ value on an error that means that the old mechanism won't 2880 * work either (so it shouldn't be tried). 2881 */ 2882 static int 2883 activate_new(pcap_t *handle) 2884 { 2885 #ifdef HAVE_PF_PACKET_SOCKETS 2886 const char *device = handle->opt.source; 2887 int is_any_device = (strcmp(device, "any") == 0); 2888 int sock_fd = -1, arptype; 2889 #ifdef HAVE_PACKET_AUXDATA 2890 int val; 2891 #endif 2892 int err = 0; 2893 struct packet_mreq mr; 2894 2895 /* 2896 * Open a socket with protocol family packet. If the 2897 * "any" device was specified, we open a SOCK_DGRAM 2898 * socket for the cooked interface, otherwise we first 2899 * try a SOCK_RAW socket for the raw interface. 2900 */ 2901 sock_fd = is_any_device ? 2902 socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) : 2903 socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); 2904 2905 if (sock_fd == -1) { 2906 if (errno == EINVAL || errno == EAFNOSUPPORT) { 2907 /* 2908 * We don't support PF_PACKET/SOCK_whatever 2909 * sockets; try the old mechanism. 2910 */ 2911 return 0; 2912 } 2913 2914 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", 2915 pcap_strerror(errno) ); 2916 if (errno == EPERM || errno == EACCES) { 2917 /* 2918 * You don't have permission to open the 2919 * socket. 2920 */ 2921 return PCAP_ERROR_PERM_DENIED; 2922 } else { 2923 /* 2924 * Other error. 2925 */ 2926 return PCAP_ERROR; 2927 } 2928 } 2929 2930 /* It seems the kernel supports the new interface. */ 2931 handle->md.sock_packet = 0; 2932 2933 /* 2934 * Get the interface index of the loopback device. 2935 * If the attempt fails, don't fail, just set the 2936 * "md.lo_ifindex" to -1. 2937 * 2938 * XXX - can there be more than one device that loops 2939 * packets back, i.e. devices other than "lo"? If so, 2940 * we'd need to find them all, and have an array of 2941 * indices for them, and check all of them in 2942 * "pcap_read_packet()". 2943 */ 2944 handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf); 2945 2946 /* 2947 * Default value for offset to align link-layer payload 2948 * on a 4-byte boundary. 2949 */ 2950 handle->offset = 0; 2951 2952 /* 2953 * What kind of frames do we have to deal with? Fall back 2954 * to cooked mode if we have an unknown interface type 2955 * or a type we know doesn't work well in raw mode. 2956 */ 2957 if (!is_any_device) { 2958 /* Assume for now we don't need cooked mode. */ 2959 handle->md.cooked = 0; 2960 2961 if (handle->opt.rfmon) { 2962 /* 2963 * We were asked to turn on monitor mode. 2964 * Do so before we get the link-layer type, 2965 * because entering monitor mode could change 2966 * the link-layer type. 2967 */ 2968 err = enter_rfmon_mode(handle, sock_fd, device); 2969 if (err < 0) { 2970 /* Hard failure */ 2971 close(sock_fd); 2972 return err; 2973 } 2974 if (err == 0) { 2975 /* 2976 * Nothing worked for turning monitor mode 2977 * on. 2978 */ 2979 close(sock_fd); 2980 return PCAP_ERROR_RFMON_NOTSUP; 2981 } 2982 2983 /* 2984 * Either monitor mode has been turned on for 2985 * the device, or we've been given a different 2986 * device to open for monitor mode. If we've 2987 * been given a different device, use it. 2988 */ 2989 if (handle->md.mondevice != NULL) 2990 device = handle->md.mondevice; 2991 } 2992 arptype = iface_get_arptype(sock_fd, device, handle->errbuf); 2993 if (arptype < 0) { 2994 close(sock_fd); 2995 return arptype; 2996 } 2997 map_arphrd_to_dlt(handle, arptype, 1); 2998 if (handle->linktype == -1 || 2999 handle->linktype == DLT_LINUX_SLL || 3000 handle->linktype == DLT_LINUX_IRDA || 3001 handle->linktype == DLT_LINUX_LAPD || 3002 (handle->linktype == DLT_EN10MB && 3003 (strncmp("isdn", device, 4) == 0 || 3004 strncmp("isdY", device, 4) == 0))) { 3005 /* 3006 * Unknown interface type (-1), or a 3007 * device we explicitly chose to run 3008 * in cooked mode (e.g., PPP devices), 3009 * or an ISDN device (whose link-layer 3010 * type we can only determine by using 3011 * APIs that may be different on different 3012 * kernels) - reopen in cooked mode. 3013 */ 3014 if (close(sock_fd) == -1) { 3015 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3016 "close: %s", pcap_strerror(errno)); 3017 return PCAP_ERROR; 3018 } 3019 sock_fd = socket(PF_PACKET, SOCK_DGRAM, 3020 htons(ETH_P_ALL)); 3021 if (sock_fd == -1) { 3022 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3023 "socket: %s", pcap_strerror(errno)); 3024 if (errno == EPERM || errno == EACCES) { 3025 /* 3026 * You don't have permission to 3027 * open the socket. 3028 */ 3029 return PCAP_ERROR_PERM_DENIED; 3030 } else { 3031 /* 3032 * Other error. 3033 */ 3034 return PCAP_ERROR; 3035 } 3036 } 3037 handle->md.cooked = 1; 3038 3039 /* 3040 * Get rid of any link-layer type list 3041 * we allocated - this only supports cooked 3042 * capture. 3043 */ 3044 if (handle->dlt_list != NULL) { 3045 free(handle->dlt_list); 3046 handle->dlt_list = NULL; 3047 handle->dlt_count = 0; 3048 } 3049 3050 if (handle->linktype == -1) { 3051 /* 3052 * Warn that we're falling back on 3053 * cooked mode; we may want to 3054 * update "map_arphrd_to_dlt()" 3055 * to handle the new type. 3056 */ 3057 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3058 "arptype %d not " 3059 "supported by libpcap - " 3060 "falling back to cooked " 3061 "socket", 3062 arptype); 3063 } 3064 3065 /* 3066 * IrDA capture is not a real "cooked" capture, 3067 * it's IrLAP frames, not IP packets. The 3068 * same applies to LAPD capture. 3069 */ 3070 if (handle->linktype != DLT_LINUX_IRDA && 3071 handle->linktype != DLT_LINUX_LAPD) 3072 handle->linktype = DLT_LINUX_SLL; 3073 } 3074 3075 handle->md.ifindex = iface_get_id(sock_fd, device, 3076 handle->errbuf); 3077 if (handle->md.ifindex == -1) { 3078 close(sock_fd); 3079 return PCAP_ERROR; 3080 } 3081 3082 if ((err = iface_bind(sock_fd, handle->md.ifindex, 3083 handle->errbuf)) != 1) { 3084 close(sock_fd); 3085 if (err < 0) 3086 return err; 3087 else 3088 return 0; /* try old mechanism */ 3089 } 3090 } else { 3091 /* 3092 * The "any" device. 3093 */ 3094 if (handle->opt.rfmon) { 3095 /* 3096 * It doesn't support monitor mode. 3097 */ 3098 return PCAP_ERROR_RFMON_NOTSUP; 3099 } 3100 3101 /* 3102 * It uses cooked mode. 3103 */ 3104 handle->md.cooked = 1; 3105 handle->linktype = DLT_LINUX_SLL; 3106 3107 /* 3108 * We're not bound to a device. 3109 * For now, we're using this as an indication 3110 * that we can't transmit; stop doing that only 3111 * if we figure out how to transmit in cooked 3112 * mode. 3113 */ 3114 handle->md.ifindex = -1; 3115 } 3116 3117 /* 3118 * Select promiscuous mode on if "promisc" is set. 3119 * 3120 * Do not turn allmulti mode on if we don't select 3121 * promiscuous mode - on some devices (e.g., Orinoco 3122 * wireless interfaces), allmulti mode isn't supported 3123 * and the driver implements it by turning promiscuous 3124 * mode on, and that screws up the operation of the 3125 * card as a normal networking interface, and on no 3126 * other platform I know of does starting a non- 3127 * promiscuous capture affect which multicast packets 3128 * are received by the interface. 3129 */ 3130 3131 /* 3132 * Hmm, how can we set promiscuous mode on all interfaces? 3133 * I am not sure if that is possible at all. For now, we 3134 * silently ignore attempts to turn promiscuous mode on 3135 * for the "any" device (so you don't have to explicitly 3136 * disable it in programs such as tcpdump). 3137 */ 3138 3139 if (!is_any_device && handle->opt.promisc) { 3140 memset(&mr, 0, sizeof(mr)); 3141 mr.mr_ifindex = handle->md.ifindex; 3142 mr.mr_type = PACKET_MR_PROMISC; 3143 if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, 3144 &mr, sizeof(mr)) == -1) { 3145 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3146 "setsockopt: %s", pcap_strerror(errno)); 3147 close(sock_fd); 3148 return PCAP_ERROR; 3149 } 3150 } 3151 3152 /* Enable auxillary data if supported and reserve room for 3153 * reconstructing VLAN headers. */ 3154 #ifdef HAVE_PACKET_AUXDATA 3155 val = 1; 3156 if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, 3157 sizeof(val)) == -1 && errno != ENOPROTOOPT) { 3158 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3159 "setsockopt: %s", pcap_strerror(errno)); 3160 close(sock_fd); 3161 return PCAP_ERROR; 3162 } 3163 handle->offset += VLAN_TAG_LEN; 3164 #endif /* HAVE_PACKET_AUXDATA */ 3165 3166 /* 3167 * This is a 2.2[.x] or later kernel (we know that 3168 * because we're not using a SOCK_PACKET socket - 3169 * PF_PACKET is supported only in 2.2 and later 3170 * kernels). 3171 * 3172 * We can safely pass "recvfrom()" a byte count 3173 * based on the snapshot length. 3174 * 3175 * If we're in cooked mode, make the snapshot length 3176 * large enough to hold a "cooked mode" header plus 3177 * 1 byte of packet data (so we don't pass a byte 3178 * count of 0 to "recvfrom()"). 3179 */ 3180 if (handle->md.cooked) { 3181 if (handle->snapshot < SLL_HDR_LEN + 1) 3182 handle->snapshot = SLL_HDR_LEN + 1; 3183 } 3184 handle->bufsize = handle->snapshot; 3185 3186 /* Save the socket FD in the pcap structure */ 3187 handle->fd = sock_fd; 3188 3189 return 1; 3190 #else 3191 strncpy(ebuf, 3192 "New packet capturing interface not supported by build " 3193 "environment", PCAP_ERRBUF_SIZE); 3194 return 0; 3195 #endif 3196 } 3197 3198 #ifdef HAVE_PACKET_RING 3199 /* 3200 * Attempt to activate with memory-mapped access. 3201 * 3202 * On success, returns 1, and sets *status to 0 if there are no warnings 3203 * or to a PCAP_WARNING_ code if there is a warning. 3204 * 3205 * On failure due to lack of support for memory-mapped capture, returns 3206 * 0. 3207 * 3208 * On error, returns -1, and sets *status to the appropriate error code; 3209 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. 3210 */ 3211 static int 3212 activate_mmap(pcap_t *handle, int *status) 3213 { 3214 int ret; 3215 3216 /* 3217 * Attempt to allocate a buffer to hold the contents of one 3218 * packet, for use by the oneshot callback. 3219 */ 3220 handle->md.oneshot_buffer = malloc(handle->snapshot); 3221 if (handle->md.oneshot_buffer == NULL) { 3222 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3223 "can't allocate oneshot buffer: %s", 3224 pcap_strerror(errno)); 3225 *status = PCAP_ERROR; 3226 return -1; 3227 } 3228 3229 if (handle->opt.buffer_size == 0) { 3230 /* by default request 2M for the ring buffer */ 3231 handle->opt.buffer_size = 2*1024*1024; 3232 } 3233 ret = prepare_tpacket_socket(handle); 3234 if (ret == -1) { 3235 free(handle->md.oneshot_buffer); 3236 *status = PCAP_ERROR; 3237 return ret; 3238 } 3239 ret = create_ring(handle, status); 3240 if (ret == 0) { 3241 /* 3242 * We don't support memory-mapped capture; our caller 3243 * will fall back on reading from the socket. 3244 */ 3245 free(handle->md.oneshot_buffer); 3246 return 0; 3247 } 3248 if (ret == -1) { 3249 /* 3250 * Error attempting to enable memory-mapped capture; 3251 * fail. create_ring() has set *status. 3252 */ 3253 free(handle->md.oneshot_buffer); 3254 return -1; 3255 } 3256 3257 /* 3258 * Success. *status has been set either to 0 if there are no 3259 * warnings or to a PCAP_WARNING_ value if there is a warning. 3260 * 3261 * Override some defaults and inherit the other fields from 3262 * activate_new. 3263 * handle->offset is used to get the current position into the rx ring. 3264 * handle->cc is used to store the ring size. 3265 */ 3266 handle->read_op = pcap_read_linux_mmap; 3267 handle->cleanup_op = pcap_cleanup_linux_mmap; 3268 handle->setfilter_op = pcap_setfilter_linux_mmap; 3269 handle->setnonblock_op = pcap_setnonblock_mmap; 3270 handle->getnonblock_op = pcap_getnonblock_mmap; 3271 handle->oneshot_callback = pcap_oneshot_mmap; 3272 handle->selectable_fd = handle->fd; 3273 return 1; 3274 } 3275 #else /* HAVE_PACKET_RING */ 3276 static int 3277 activate_mmap(pcap_t *handle _U_, int *status _U_) 3278 { 3279 return 0; 3280 } 3281 #endif /* HAVE_PACKET_RING */ 3282 3283 #ifdef HAVE_PACKET_RING 3284 /* 3285 * Attempt to set the socket to version 2 of the memory-mapped header. 3286 * Return 1 if we succeed or if we fail because version 2 isn't 3287 * supported; return -1 on any other error, and set handle->errbuf. 3288 */ 3289 static int 3290 prepare_tpacket_socket(pcap_t *handle) 3291 { 3292 #ifdef HAVE_TPACKET2 3293 socklen_t len; 3294 int val; 3295 #endif 3296 3297 handle->md.tp_version = TPACKET_V1; 3298 handle->md.tp_hdrlen = sizeof(struct tpacket_hdr); 3299 3300 #ifdef HAVE_TPACKET2 3301 /* Probe whether kernel supports TPACKET_V2 */ 3302 val = TPACKET_V2; 3303 len = sizeof(val); 3304 if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { 3305 if (errno == ENOPROTOOPT) 3306 return 1; /* no - just drive on */ 3307 3308 /* Yes - treat as a failure. */ 3309 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3310 "can't get TPACKET_V2 header len on packet socket: %s", 3311 pcap_strerror(errno)); 3312 return -1; 3313 } 3314 handle->md.tp_hdrlen = val; 3315 3316 val = TPACKET_V2; 3317 if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, 3318 sizeof(val)) < 0) { 3319 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3320 "can't activate TPACKET_V2 on packet socket: %s", 3321 pcap_strerror(errno)); 3322 return -1; 3323 } 3324 handle->md.tp_version = TPACKET_V2; 3325 3326 /* Reserve space for VLAN tag reconstruction */ 3327 val = VLAN_TAG_LEN; 3328 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val, 3329 sizeof(val)) < 0) { 3330 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3331 "can't set up reserve on packet socket: %s", 3332 pcap_strerror(errno)); 3333 return -1; 3334 } 3335 3336 #endif /* HAVE_TPACKET2 */ 3337 return 1; 3338 } 3339 3340 /* 3341 * Attempt to set up memory-mapped access. 3342 * 3343 * On success, returns 1, and sets *status to 0 if there are no warnings 3344 * or to a PCAP_WARNING_ code if there is a warning. 3345 * 3346 * On failure due to lack of support for memory-mapped capture, returns 3347 * 0. 3348 * 3349 * On error, returns -1, and sets *status to the appropriate error code; 3350 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. 3351 */ 3352 static int 3353 create_ring(pcap_t *handle, int *status) 3354 { 3355 unsigned i, j, frames_per_block; 3356 struct tpacket_req req; 3357 socklen_t len; 3358 unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff; 3359 unsigned int frame_size; 3360 3361 /* 3362 * Start out assuming no warnings or errors. 3363 */ 3364 *status = 0; 3365 3366 /* Note that with large snapshot length (say 64K, which is the default 3367 * for recent versions of tcpdump, the value that "-s 0" has given 3368 * for a long time with tcpdump, and the default in Wireshark/TShark), 3369 * if we use the snapshot length to calculate the frame length, 3370 * only a few frames will be available in the ring even with pretty 3371 * large ring size (and a lot of memory will be unused). 3372 * 3373 * Ideally, we should choose a frame length based on the 3374 * minimum of the specified snapshot length and the maximum 3375 * packet size. That's not as easy as it sounds; consider, for 3376 * example, an 802.11 interface in monitor mode, where the 3377 * frame would include a radiotap header, where the maximum 3378 * radiotap header length is device-dependent. 3379 * 3380 * So, for now, we just do this for Ethernet devices, where 3381 * there's no metadata header, and the link-layer header is 3382 * fixed length. We can get the maximum packet size by 3383 * adding 18, the Ethernet header length plus the CRC length 3384 * (just in case we happen to get the CRC in the packet), to 3385 * the MTU of the interface; we fetch the MTU in the hopes 3386 * that it reflects support for jumbo frames. (Even if the 3387 * interface is just being used for passive snooping, the driver 3388 * might set the size of buffers in the receive ring based on 3389 * the MTU, so that the MTU limits the maximum size of packets 3390 * that we can receive.) 3391 * 3392 * We don't do that if segmentation/fragmentation or receive 3393 * offload are enabled, so we don't get rudely surprised by 3394 * "packets" bigger than the MTU. */ 3395 frame_size = handle->snapshot; 3396 if (handle->linktype == DLT_EN10MB) { 3397 int mtu; 3398 int offload; 3399 3400 offload = iface_get_offload(handle); 3401 if (offload == -1) { 3402 *status = PCAP_ERROR; 3403 return -1; 3404 } 3405 if (!offload) { 3406 mtu = iface_get_mtu(handle->fd, handle->opt.source, 3407 handle->errbuf); 3408 if (mtu == -1) { 3409 *status = PCAP_ERROR; 3410 return -1; 3411 } 3412 if (frame_size > mtu + 18) 3413 frame_size = mtu + 18; 3414 } 3415 } 3416 3417 /* NOTE: calculus matching those in tpacket_rcv() 3418 * in linux-2.6/net/packet/af_packet.c 3419 */ 3420 len = sizeof(sk_type); 3421 if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type, &len) < 0) { 3422 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); 3423 *status = PCAP_ERROR; 3424 return -1; 3425 } 3426 #ifdef PACKET_RESERVE 3427 len = sizeof(tp_reserve); 3428 if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, &len) < 0) { 3429 if (errno != ENOPROTOOPT) { 3430 /* 3431 * ENOPROTOOPT means "kernel doesn't support 3432 * PACKET_RESERVE", in which case we fall back 3433 * as best we can. 3434 */ 3435 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); 3436 *status = PCAP_ERROR; 3437 return -1; 3438 } 3439 tp_reserve = 0; /* older kernel, reserve not supported */ 3440 } 3441 #else 3442 tp_reserve = 0; /* older kernel, reserve not supported */ 3443 #endif 3444 maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE; 3445 /* XXX: in the kernel maclen is calculated from 3446 * LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len 3447 * in: packet_snd() in linux-2.6/net/packet/af_packet.c 3448 * then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c 3449 * then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c 3450 * but I see no way to get those sizes in userspace, 3451 * like for instance with an ifreq ioctl(); 3452 * the best thing I've found so far is MAX_HEADER in the kernel 3453 * part of linux-2.6/include/linux/netdevice.h 3454 * which goes up to 128+48=176; since pcap-linux.c defines 3455 * a MAX_LINKHEADER_SIZE of 256 which is greater than that, 3456 * let's use it.. maybe is it even large enough to directly 3457 * replace macoff.. 3458 */ 3459 tp_hdrlen = TPACKET_ALIGN(handle->md.tp_hdrlen) + sizeof(struct sockaddr_ll) ; 3460 netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve; 3461 /* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN of 3462 * netoff, which contradicts 3463 * linux-2.6/Documentation/networking/packet_mmap.txt 3464 * documenting that: 3465 * "- Gap, chosen so that packet data (Start+tp_net) 3466 * aligns to TPACKET_ALIGNMENT=16" 3467 */ 3468 /* NOTE: in linux-2.6/include/linux/skbuff.h: 3469 * "CPUs often take a performance hit 3470 * when accessing unaligned memory locations" 3471 */ 3472 macoff = netoff - maclen; 3473 req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size); 3474 req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; 3475 3476 /* compute the minumum block size that will handle this frame. 3477 * The block has to be page size aligned. 3478 * The max block size allowed by the kernel is arch-dependent and 3479 * it's not explicitly checked here. */ 3480 req.tp_block_size = getpagesize(); 3481 while (req.tp_block_size < req.tp_frame_size) 3482 req.tp_block_size <<= 1; 3483 3484 frames_per_block = req.tp_block_size/req.tp_frame_size; 3485 3486 /* 3487 * PACKET_TIMESTAMP was added after linux/net_tstamp.h was, 3488 * so we check for PACKET_TIMESTAMP. We check for 3489 * linux/net_tstamp.h just in case a system somehow has 3490 * PACKET_TIMESTAMP but not linux/net_tstamp.h; that might 3491 * be unnecessary. 3492 * 3493 * SIOCSHWTSTAMP was introduced in the patch that introduced 3494 * linux/net_tstamp.h, so we don't bother checking whether 3495 * SIOCSHWTSTAMP is defined (if your Linux system has 3496 * linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your 3497 * Linux system is badly broken). 3498 */ 3499 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) 3500 /* 3501 * If we were told to do so, ask the kernel and the driver 3502 * to use hardware timestamps. 3503 * 3504 * Hardware timestamps are only supported with mmapped 3505 * captures. 3506 */ 3507 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER || 3508 handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) { 3509 struct hwtstamp_config hwconfig; 3510 struct ifreq ifr; 3511 int timesource; 3512 3513 /* 3514 * Ask for hardware time stamps on all packets, 3515 * including transmitted packets. 3516 */ 3517 memset(&hwconfig, 0, sizeof(hwconfig)); 3518 hwconfig.tx_type = HWTSTAMP_TX_ON; 3519 hwconfig.rx_filter = HWTSTAMP_FILTER_ALL; 3520 3521 memset(&ifr, 0, sizeof(ifr)); 3522 strcpy(ifr.ifr_name, handle->opt.source); 3523 ifr.ifr_data = (void *)&hwconfig; 3524 3525 if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) { 3526 switch (errno) { 3527 3528 case EPERM: 3529 /* 3530 * Treat this as an error, as the 3531 * user should try to run this 3532 * with the appropriate privileges - 3533 * and, if they can't, shouldn't 3534 * try requesting hardware time stamps. 3535 */ 3536 *status = PCAP_ERROR_PERM_DENIED; 3537 return -1; 3538 3539 case EOPNOTSUPP: 3540 /* 3541 * Treat this as a warning, as the 3542 * only way to fix the warning is to 3543 * get an adapter that supports hardware 3544 * time stamps. We'll just fall back 3545 * on the standard host time stamps. 3546 */ 3547 *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP; 3548 break; 3549 3550 default: 3551 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3552 "SIOCSHWTSTAMP failed: %s", 3553 pcap_strerror(errno)); 3554 *status = PCAP_ERROR; 3555 return -1; 3556 } 3557 } else { 3558 /* 3559 * Well, that worked. Now specify the type of 3560 * hardware time stamp we want for this 3561 * socket. 3562 */ 3563 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) { 3564 /* 3565 * Hardware timestamp, synchronized 3566 * with the system clock. 3567 */ 3568 timesource = SOF_TIMESTAMPING_SYS_HARDWARE; 3569 } else { 3570 /* 3571 * PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware 3572 * timestamp, not synchronized with the 3573 * system clock. 3574 */ 3575 timesource = SOF_TIMESTAMPING_RAW_HARDWARE; 3576 } 3577 if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP, 3578 (void *)×ource, sizeof(timesource))) { 3579 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3580 "can't set PACKET_TIMESTAMP: %s", 3581 pcap_strerror(errno)); 3582 *status = PCAP_ERROR; 3583 return -1; 3584 } 3585 } 3586 } 3587 #endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */ 3588 3589 /* ask the kernel to create the ring */ 3590 retry: 3591 req.tp_block_nr = req.tp_frame_nr / frames_per_block; 3592 3593 /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ 3594 req.tp_frame_nr = req.tp_block_nr * frames_per_block; 3595 3596 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, 3597 (void *) &req, sizeof(req))) { 3598 if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { 3599 /* 3600 * Memory failure; try to reduce the requested ring 3601 * size. 3602 * 3603 * We used to reduce this by half -- do 5% instead. 3604 * That may result in more iterations and a longer 3605 * startup, but the user will be much happier with 3606 * the resulting buffer size. 3607 */ 3608 if (req.tp_frame_nr < 20) 3609 req.tp_frame_nr -= 1; 3610 else 3611 req.tp_frame_nr -= req.tp_frame_nr/20; 3612 goto retry; 3613 } 3614 if (errno == ENOPROTOOPT) { 3615 /* 3616 * We don't have ring buffer support in this kernel. 3617 */ 3618 return 0; 3619 } 3620 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3621 "can't create rx ring on packet socket: %s", 3622 pcap_strerror(errno)); 3623 *status = PCAP_ERROR; 3624 return -1; 3625 } 3626 3627 /* memory map the rx ring */ 3628 handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size; 3629 handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen, 3630 PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); 3631 if (handle->md.mmapbuf == MAP_FAILED) { 3632 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3633 "can't mmap rx ring: %s", pcap_strerror(errno)); 3634 3635 /* clear the allocated ring on error*/ 3636 destroy_ring(handle); 3637 *status = PCAP_ERROR; 3638 return -1; 3639 } 3640 3641 /* allocate a ring for each frame header pointer*/ 3642 handle->cc = req.tp_frame_nr; 3643 handle->buffer = malloc(handle->cc * sizeof(union thdr *)); 3644 if (!handle->buffer) { 3645 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3646 "can't allocate ring of frame headers: %s", 3647 pcap_strerror(errno)); 3648 3649 destroy_ring(handle); 3650 *status = PCAP_ERROR; 3651 return -1; 3652 } 3653 3654 /* fill the header ring with proper frame ptr*/ 3655 handle->offset = 0; 3656 for (i=0; i<req.tp_block_nr; ++i) { 3657 void *base = &handle->md.mmapbuf[i*req.tp_block_size]; 3658 for (j=0; j<frames_per_block; ++j, ++handle->offset) { 3659 RING_GET_FRAME(handle) = base; 3660 base += req.tp_frame_size; 3661 } 3662 } 3663 3664 handle->bufsize = req.tp_frame_size; 3665 handle->offset = 0; 3666 return 1; 3667 } 3668 3669 /* free all ring related resources*/ 3670 static void 3671 destroy_ring(pcap_t *handle) 3672 { 3673 /* tell the kernel to destroy the ring*/ 3674 struct tpacket_req req; 3675 memset(&req, 0, sizeof(req)); 3676 setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, 3677 (void *) &req, sizeof(req)); 3678 3679 /* if ring is mapped, unmap it*/ 3680 if (handle->md.mmapbuf) { 3681 /* do not test for mmap failure, as we can't recover from any error */ 3682 munmap(handle->md.mmapbuf, handle->md.mmapbuflen); 3683 handle->md.mmapbuf = NULL; 3684 } 3685 } 3686 3687 /* 3688 * Special one-shot callback, used for pcap_next() and pcap_next_ex(), 3689 * for Linux mmapped capture. 3690 * 3691 * The problem is that pcap_next() and pcap_next_ex() expect the packet 3692 * data handed to the callback to be valid after the callback returns, 3693 * but pcap_read_linux_mmap() has to release that packet as soon as 3694 * the callback returns (otherwise, the kernel thinks there's still 3695 * at least one unprocessed packet available in the ring, so a select() 3696 * will immediately return indicating that there's data to process), so, 3697 * in the callback, we have to make a copy of the packet. 3698 * 3699 * Yes, this means that, if the capture is using the ring buffer, using 3700 * pcap_next() or pcap_next_ex() requires more copies than using 3701 * pcap_loop() or pcap_dispatch(). If that bothers you, don't use 3702 * pcap_next() or pcap_next_ex(). 3703 */ 3704 static void 3705 pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, 3706 const u_char *bytes) 3707 { 3708 struct oneshot_userdata *sp = (struct oneshot_userdata *)user; 3709 3710 *sp->hdr = *h; 3711 memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen); 3712 *sp->pkt = sp->pd->md.oneshot_buffer; 3713 } 3714 3715 static void 3716 pcap_cleanup_linux_mmap( pcap_t *handle ) 3717 { 3718 destroy_ring(handle); 3719 if (handle->md.oneshot_buffer != NULL) { 3720 free(handle->md.oneshot_buffer); 3721 handle->md.oneshot_buffer = NULL; 3722 } 3723 pcap_cleanup_linux(handle); 3724 } 3725 3726 3727 static int 3728 pcap_getnonblock_mmap(pcap_t *p, char *errbuf) 3729 { 3730 /* use negative value of timeout to indicate non blocking ops */ 3731 return (p->md.timeout<0); 3732 } 3733 3734 static int 3735 pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf) 3736 { 3737 /* map each value to the corresponding 2's complement, to 3738 * preserve the timeout value provided with pcap_set_timeout */ 3739 if (nonblock) { 3740 if (p->md.timeout >= 0) { 3741 /* 3742 * Timeout is non-negative, so we're not already 3743 * in non-blocking mode; set it to the 2's 3744 * complement, to make it negative, as an 3745 * indication that we're in non-blocking mode. 3746 */ 3747 p->md.timeout = p->md.timeout*-1 - 1; 3748 } 3749 } else { 3750 if (p->md.timeout < 0) { 3751 /* 3752 * Timeout is negative, so we're not already 3753 * in blocking mode; reverse the previous 3754 * operation, to make the timeout non-negative 3755 * again. 3756 */ 3757 p->md.timeout = (p->md.timeout+1)*-1; 3758 } 3759 } 3760 return 0; 3761 } 3762 3763 static inline union thdr * 3764 pcap_get_ring_frame(pcap_t *handle, int status) 3765 { 3766 union thdr h; 3767 3768 h.raw = RING_GET_FRAME(handle); 3769 switch (handle->md.tp_version) { 3770 case TPACKET_V1: 3771 if (status != (h.h1->tp_status ? TP_STATUS_USER : 3772 TP_STATUS_KERNEL)) 3773 return NULL; 3774 break; 3775 #ifdef HAVE_TPACKET2 3776 case TPACKET_V2: 3777 if (status != (h.h2->tp_status ? TP_STATUS_USER : 3778 TP_STATUS_KERNEL)) 3779 return NULL; 3780 break; 3781 #endif 3782 } 3783 return h.raw; 3784 } 3785 3786 #ifndef POLLRDHUP 3787 #define POLLRDHUP 0 3788 #endif 3789 3790 static int 3791 pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, 3792 u_char *user) 3793 { 3794 int timeout; 3795 int pkts = 0; 3796 char c; 3797 3798 /* wait for frames availability.*/ 3799 if (!pcap_get_ring_frame(handle, TP_STATUS_USER)) { 3800 struct pollfd pollinfo; 3801 int ret; 3802 3803 pollinfo.fd = handle->fd; 3804 pollinfo.events = POLLIN; 3805 3806 if (handle->md.timeout == 0) 3807 timeout = -1; /* block forever */ 3808 else if (handle->md.timeout > 0) 3809 timeout = handle->md.timeout; /* block for that amount of time */ 3810 else 3811 timeout = 0; /* non-blocking mode - poll to pick up errors */ 3812 do { 3813 ret = poll(&pollinfo, 1, timeout); 3814 if (ret < 0 && errno != EINTR) { 3815 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3816 "can't poll on packet socket: %s", 3817 pcap_strerror(errno)); 3818 return PCAP_ERROR; 3819 } else if (ret > 0 && 3820 (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) { 3821 /* 3822 * There's some indication other than 3823 * "you can read on this descriptor" on 3824 * the descriptor. 3825 */ 3826 if (pollinfo.revents & (POLLHUP | POLLRDHUP)) { 3827 snprintf(handle->errbuf, 3828 PCAP_ERRBUF_SIZE, 3829 "Hangup on packet socket"); 3830 return PCAP_ERROR; 3831 } 3832 if (pollinfo.revents & POLLERR) { 3833 /* 3834 * A recv() will give us the 3835 * actual error code. 3836 * 3837 * XXX - make the socket non-blocking? 3838 */ 3839 if (recv(handle->fd, &c, sizeof c, 3840 MSG_PEEK) != -1) 3841 continue; /* what, no error? */ 3842 if (errno == ENETDOWN) { 3843 /* 3844 * The device on which we're 3845 * capturing went away. 3846 * 3847 * XXX - we should really return 3848 * PCAP_ERROR_IFACE_NOT_UP, 3849 * but pcap_dispatch() etc. 3850 * aren't defined to return 3851 * that. 3852 */ 3853 snprintf(handle->errbuf, 3854 PCAP_ERRBUF_SIZE, 3855 "The interface went down"); 3856 } else { 3857 snprintf(handle->errbuf, 3858 PCAP_ERRBUF_SIZE, 3859 "Error condition on packet socket: %s", 3860 strerror(errno)); 3861 } 3862 return PCAP_ERROR; 3863 } 3864 if (pollinfo.revents & POLLNVAL) { 3865 snprintf(handle->errbuf, 3866 PCAP_ERRBUF_SIZE, 3867 "Invalid polling request on packet socket"); 3868 return PCAP_ERROR; 3869 } 3870 } 3871 /* check for break loop condition on interrupted syscall*/ 3872 if (handle->break_loop) { 3873 handle->break_loop = 0; 3874 return PCAP_ERROR_BREAK; 3875 } 3876 } while (ret < 0); 3877 } 3878 3879 /* non-positive values of max_packets are used to require all 3880 * packets currently available in the ring */ 3881 while ((pkts < max_packets) || (max_packets <= 0)) { 3882 int run_bpf; 3883 struct sockaddr_ll *sll; 3884 struct pcap_pkthdr pcaphdr; 3885 unsigned char *bp; 3886 union thdr h; 3887 unsigned int tp_len; 3888 unsigned int tp_mac; 3889 unsigned int tp_snaplen; 3890 unsigned int tp_sec; 3891 unsigned int tp_usec; 3892 3893 h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); 3894 if (!h.raw) 3895 break; 3896 3897 switch (handle->md.tp_version) { 3898 case TPACKET_V1: 3899 tp_len = h.h1->tp_len; 3900 tp_mac = h.h1->tp_mac; 3901 tp_snaplen = h.h1->tp_snaplen; 3902 tp_sec = h.h1->tp_sec; 3903 tp_usec = h.h1->tp_usec; 3904 break; 3905 #ifdef HAVE_TPACKET2 3906 case TPACKET_V2: 3907 tp_len = h.h2->tp_len; 3908 tp_mac = h.h2->tp_mac; 3909 tp_snaplen = h.h2->tp_snaplen; 3910 tp_sec = h.h2->tp_sec; 3911 tp_usec = h.h2->tp_nsec / 1000; 3912 break; 3913 #endif 3914 default: 3915 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3916 "unsupported tpacket version %d", 3917 handle->md.tp_version); 3918 return -1; 3919 } 3920 /* perform sanity check on internal offset. */ 3921 if (tp_mac + tp_snaplen > handle->bufsize) { 3922 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3923 "corrupted frame on kernel ring mac " 3924 "offset %d + caplen %d > frame len %d", 3925 tp_mac, tp_snaplen, handle->bufsize); 3926 return -1; 3927 } 3928 3929 /* run filter on received packet 3930 * If the kernel filtering is enabled we need to run the 3931 * filter until all the frames present into the ring 3932 * at filter creation time are processed. 3933 * In such case md.use_bpf is used as a counter for the 3934 * packet we need to filter. 3935 * Note: alternatively it could be possible to stop applying 3936 * the filter when the ring became empty, but it can possibly 3937 * happen a lot later... */ 3938 bp = (unsigned char*)h.raw + tp_mac; 3939 run_bpf = (!handle->md.use_bpf) || 3940 ((handle->md.use_bpf>1) && handle->md.use_bpf--); 3941 if (run_bpf && handle->fcode.bf_insns && 3942 (bpf_filter(handle->fcode.bf_insns, bp, 3943 tp_len, tp_snaplen) == 0)) 3944 goto skip; 3945 3946 /* 3947 * Do checks based on packet direction. 3948 */ 3949 sll = (void *)h.raw + TPACKET_ALIGN(handle->md.tp_hdrlen); 3950 if (sll->sll_pkttype == PACKET_OUTGOING) { 3951 /* 3952 * Outgoing packet. 3953 * If this is from the loopback device, reject it; 3954 * we'll see the packet as an incoming packet as well, 3955 * and we don't want to see it twice. 3956 */ 3957 if (sll->sll_ifindex == handle->md.lo_ifindex) 3958 goto skip; 3959 3960 /* 3961 * If the user only wants incoming packets, reject it. 3962 */ 3963 if (handle->direction == PCAP_D_IN) 3964 goto skip; 3965 } else { 3966 /* 3967 * Incoming packet. 3968 * If the user only wants outgoing packets, reject it. 3969 */ 3970 if (handle->direction == PCAP_D_OUT) 3971 goto skip; 3972 } 3973 3974 /* get required packet info from ring header */ 3975 pcaphdr.ts.tv_sec = tp_sec; 3976 pcaphdr.ts.tv_usec = tp_usec; 3977 pcaphdr.caplen = tp_snaplen; 3978 pcaphdr.len = tp_len; 3979 3980 /* if required build in place the sll header*/ 3981 if (handle->md.cooked) { 3982 struct sll_header *hdrp; 3983 3984 /* 3985 * The kernel should have left us with enough 3986 * space for an sll header; back up the packet 3987 * data pointer into that space, as that'll be 3988 * the beginning of the packet we pass to the 3989 * callback. 3990 */ 3991 bp -= SLL_HDR_LEN; 3992 3993 /* 3994 * Let's make sure that's past the end of 3995 * the tpacket header, i.e. >= 3996 * ((u_char *)thdr + TPACKET_HDRLEN), so we 3997 * don't step on the header when we construct 3998 * the sll header. 3999 */ 4000 if (bp < (u_char *)h.raw + 4001 TPACKET_ALIGN(handle->md.tp_hdrlen) + 4002 sizeof(struct sockaddr_ll)) { 4003 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4004 "cooked-mode frame doesn't have room for sll header"); 4005 return -1; 4006 } 4007 4008 /* 4009 * OK, that worked; construct the sll header. 4010 */ 4011 hdrp = (struct sll_header *)bp; 4012 hdrp->sll_pkttype = map_packet_type_to_sll_type( 4013 sll->sll_pkttype); 4014 hdrp->sll_hatype = htons(sll->sll_hatype); 4015 hdrp->sll_halen = htons(sll->sll_halen); 4016 memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN); 4017 hdrp->sll_protocol = sll->sll_protocol; 4018 4019 /* update packet len */ 4020 pcaphdr.caplen += SLL_HDR_LEN; 4021 pcaphdr.len += SLL_HDR_LEN; 4022 } 4023 4024 #ifdef HAVE_TPACKET2 4025 if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci && 4026 tp_snaplen >= 2 * ETH_ALEN) { 4027 struct vlan_tag *tag; 4028 4029 bp -= VLAN_TAG_LEN; 4030 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); 4031 4032 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); 4033 tag->vlan_tpid = htons(ETH_P_8021Q); 4034 tag->vlan_tci = htons(h.h2->tp_vlan_tci); 4035 4036 pcaphdr.caplen += VLAN_TAG_LEN; 4037 pcaphdr.len += VLAN_TAG_LEN; 4038 } 4039 #endif 4040 4041 /* 4042 * The only way to tell the kernel to cut off the 4043 * packet at a snapshot length is with a filter program; 4044 * if there's no filter program, the kernel won't cut 4045 * the packet off. 4046 * 4047 * Trim the snapshot length to be no longer than the 4048 * specified snapshot length. 4049 */ 4050 if (pcaphdr.caplen > handle->snapshot) 4051 pcaphdr.caplen = handle->snapshot; 4052 4053 /* pass the packet to the user */ 4054 pkts++; 4055 callback(user, &pcaphdr, bp); 4056 handle->md.packets_read++; 4057 4058 skip: 4059 /* next packet */ 4060 switch (handle->md.tp_version) { 4061 case TPACKET_V1: 4062 h.h1->tp_status = TP_STATUS_KERNEL; 4063 break; 4064 #ifdef HAVE_TPACKET2 4065 case TPACKET_V2: 4066 h.h2->tp_status = TP_STATUS_KERNEL; 4067 break; 4068 #endif 4069 } 4070 if (++handle->offset >= handle->cc) 4071 handle->offset = 0; 4072 4073 /* check for break loop condition*/ 4074 if (handle->break_loop) { 4075 handle->break_loop = 0; 4076 return PCAP_ERROR_BREAK; 4077 } 4078 } 4079 return pkts; 4080 } 4081 4082 static int 4083 pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) 4084 { 4085 int n, offset; 4086 int ret; 4087 4088 /* 4089 * Don't rewrite "ret" instructions; we don't need to, as 4090 * we're not reading packets with recvmsg(), and we don't 4091 * want to, as, by not rewriting them, the kernel can avoid 4092 * copying extra data. 4093 */ 4094 ret = pcap_setfilter_linux_common(handle, filter, 1); 4095 if (ret < 0) 4096 return ret; 4097 4098 /* if the kernel filter is enabled, we need to apply the filter on 4099 * all packets present into the ring. Get an upper bound of their number 4100 */ 4101 if (!handle->md.use_bpf) 4102 return ret; 4103 4104 /* walk the ring backward and count the free slot */ 4105 offset = handle->offset; 4106 if (--handle->offset < 0) 4107 handle->offset = handle->cc - 1; 4108 for (n=0; n < handle->cc; ++n) { 4109 if (--handle->offset < 0) 4110 handle->offset = handle->cc - 1; 4111 if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL)) 4112 break; 4113 } 4114 4115 /* be careful to not change current ring position */ 4116 handle->offset = offset; 4117 4118 /* store the number of packets currently present in the ring */ 4119 handle->md.use_bpf = 1 + (handle->cc - n); 4120 return ret; 4121 } 4122 4123 #endif /* HAVE_PACKET_RING */ 4124 4125 4126 #ifdef HAVE_PF_PACKET_SOCKETS 4127 /* 4128 * Return the index of the given device name. Fill ebuf and return 4129 * -1 on failure. 4130 */ 4131 static int 4132 iface_get_id(int fd, const char *device, char *ebuf) 4133 { 4134 struct ifreq ifr; 4135 4136 memset(&ifr, 0, sizeof(ifr)); 4137 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 4138 4139 if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { 4140 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4141 "SIOCGIFINDEX: %s", pcap_strerror(errno)); 4142 return -1; 4143 } 4144 4145 return ifr.ifr_ifindex; 4146 } 4147 4148 /* 4149 * Bind the socket associated with FD to the given device. 4150 * Return 1 on success, 0 if we should try a SOCK_PACKET socket, 4151 * or a PCAP_ERROR_ value on a hard error. 4152 */ 4153 static int 4154 iface_bind(int fd, int ifindex, char *ebuf) 4155 { 4156 struct sockaddr_ll sll; 4157 int err; 4158 socklen_t errlen = sizeof(err); 4159 4160 memset(&sll, 0, sizeof(sll)); 4161 sll.sll_family = AF_PACKET; 4162 sll.sll_ifindex = ifindex; 4163 sll.sll_protocol = htons(ETH_P_ALL); 4164 4165 if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) { 4166 if (errno == ENETDOWN) { 4167 /* 4168 * Return a "network down" indication, so that 4169 * the application can report that rather than 4170 * saying we had a mysterious failure and 4171 * suggest that they report a problem to the 4172 * libpcap developers. 4173 */ 4174 return PCAP_ERROR_IFACE_NOT_UP; 4175 } else { 4176 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4177 "bind: %s", pcap_strerror(errno)); 4178 return PCAP_ERROR; 4179 } 4180 } 4181 4182 /* Any pending errors, e.g., network is down? */ 4183 4184 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { 4185 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4186 "getsockopt: %s", pcap_strerror(errno)); 4187 return 0; 4188 } 4189 4190 if (err == ENETDOWN) { 4191 /* 4192 * Return a "network down" indication, so that 4193 * the application can report that rather than 4194 * saying we had a mysterious failure and 4195 * suggest that they report a problem to the 4196 * libpcap developers. 4197 */ 4198 return PCAP_ERROR_IFACE_NOT_UP; 4199 } else if (err > 0) { 4200 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4201 "bind: %s", pcap_strerror(err)); 4202 return 0; 4203 } 4204 4205 return 1; 4206 } 4207 4208 #ifdef IW_MODE_MONITOR 4209 /* 4210 * Check whether the device supports the Wireless Extensions. 4211 * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE 4212 * if the device doesn't even exist. 4213 */ 4214 static int 4215 has_wext(int sock_fd, const char *device, char *ebuf) 4216 { 4217 struct iwreq ireq; 4218 4219 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4220 sizeof ireq.ifr_ifrn.ifrn_name); 4221 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4222 if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0) 4223 return 1; /* yes */ 4224 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4225 "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); 4226 if (errno == ENODEV) 4227 return PCAP_ERROR_NO_SUCH_DEVICE; 4228 return 0; 4229 } 4230 4231 /* 4232 * Per me si va ne la citta dolente, 4233 * Per me si va ne l'etterno dolore, 4234 * ... 4235 * Lasciate ogne speranza, voi ch'intrate. 4236 * 4237 * XXX - airmon-ng does special stuff with the Orinoco driver and the 4238 * wlan-ng driver. 4239 */ 4240 typedef enum { 4241 MONITOR_WEXT, 4242 MONITOR_HOSTAP, 4243 MONITOR_PRISM, 4244 MONITOR_PRISM54, 4245 MONITOR_ACX100, 4246 MONITOR_RT2500, 4247 MONITOR_RT2570, 4248 MONITOR_RT73, 4249 MONITOR_RTL8XXX 4250 } monitor_type; 4251 4252 /* 4253 * Use the Wireless Extensions, if we have them, to try to turn monitor mode 4254 * on if it's not already on. 4255 * 4256 * Returns 1 on success, 0 if we don't support the Wireless Extensions 4257 * on this device, or a PCAP_ERROR_ value if we do support them but 4258 * we weren't able to turn monitor mode on. 4259 */ 4260 static int 4261 enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) 4262 { 4263 /* 4264 * XXX - at least some adapters require non-Wireless Extensions 4265 * mechanisms to turn monitor mode on. 4266 * 4267 * Atheros cards might require that a separate "monitor virtual access 4268 * point" be created, with later versions of the madwifi driver. 4269 * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode 4270 * monitor -bssid", which apparently spits out a line "athN" 4271 * where "athN" is the monitor mode device. To leave monitor 4272 * mode, it destroys the monitor mode device. 4273 * 4274 * Some Intel Centrino adapters might require private ioctls to get 4275 * radio headers; the ipw2200 and ipw3945 drivers allow you to 4276 * configure a separate "rtapN" interface to capture in monitor 4277 * mode without preventing the adapter from operating normally. 4278 * (airmon-ng doesn't appear to use that, though.) 4279 * 4280 * It would be Truly Wonderful if mac80211 and nl80211 cleaned this 4281 * up, and if all drivers were converted to mac80211 drivers. 4282 * 4283 * If interface {if} is a mac80211 driver, the file 4284 * /sys/class/net/{if}/phy80211 is a symlink to 4285 * /sys/class/ieee80211/{phydev}, for some {phydev}. 4286 * 4287 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at 4288 * least, has a "wmaster0" device and a "wlan0" device; the 4289 * latter is the one with the IP address. Both show up in 4290 * "tcpdump -D" output. Capturing on the wmaster0 device 4291 * captures with 802.11 headers. 4292 * 4293 * airmon-ng searches through /sys/class/net for devices named 4294 * monN, starting with mon0; as soon as one *doesn't* exist, 4295 * it chooses that as the monitor device name. If the "iw" 4296 * command exists, it does "iw dev {if} interface add {monif} 4297 * type monitor", where {monif} is the monitor device. It 4298 * then (sigh) sleeps .1 second, and then configures the 4299 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface 4300 * is a file, it writes {mondev}, without a newline, to that file, 4301 * and again (sigh) sleeps .1 second, and then iwconfig's that 4302 * device into monitor mode and configures it up. Otherwise, 4303 * you can't do monitor mode. 4304 * 4305 * All these devices are "glued" together by having the 4306 * /sys/class/net/{device}/phy80211 links pointing to the same 4307 * place, so, given a wmaster, wlan, or mon device, you can 4308 * find the other devices by looking for devices with 4309 * the same phy80211 link. 4310 * 4311 * To turn monitor mode off, delete the monitor interface, 4312 * either with "iw dev {monif} interface del" or by sending 4313 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface 4314 * 4315 * Note: if you try to create a monitor device named "monN", and 4316 * there's already a "monN" device, it fails, as least with 4317 * the netlink interface (which is what iw uses), with a return 4318 * value of -ENFILE. (Return values are negative errnos.) We 4319 * could probably use that to find an unused device. 4320 */ 4321 int err; 4322 struct iwreq ireq; 4323 struct iw_priv_args *priv; 4324 monitor_type montype; 4325 int i; 4326 __u32 cmd; 4327 struct ifreq ifr; 4328 int oldflags; 4329 int args[2]; 4330 int channel; 4331 4332 /* 4333 * Does this device *support* the Wireless Extensions? 4334 */ 4335 err = has_wext(sock_fd, device, handle->errbuf); 4336 if (err <= 0) 4337 return err; /* either it doesn't or the device doesn't even exist */ 4338 /* 4339 * Start out assuming we have no private extensions to control 4340 * radio metadata. 4341 */ 4342 montype = MONITOR_WEXT; 4343 cmd = 0; 4344 4345 /* 4346 * Try to get all the Wireless Extensions private ioctls 4347 * supported by this device. 4348 * 4349 * First, get the size of the buffer we need, by supplying no 4350 * buffer and a length of 0. If the device supports private 4351 * ioctls, it should return E2BIG, with ireq.u.data.length set 4352 * to the length we need. If it doesn't support them, it should 4353 * return EOPNOTSUPP. 4354 */ 4355 memset(&ireq, 0, sizeof ireq); 4356 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4357 sizeof ireq.ifr_ifrn.ifrn_name); 4358 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4359 ireq.u.data.pointer = (void *)args; 4360 ireq.u.data.length = 0; 4361 ireq.u.data.flags = 0; 4362 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { 4363 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4364 "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!", 4365 device); 4366 return PCAP_ERROR; 4367 } 4368 if (errno != EOPNOTSUPP) { 4369 /* 4370 * OK, it's not as if there are no private ioctls. 4371 */ 4372 if (errno != E2BIG) { 4373 /* 4374 * Failed. 4375 */ 4376 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4377 "%s: SIOCGIWPRIV: %s", device, 4378 pcap_strerror(errno)); 4379 return PCAP_ERROR; 4380 } 4381 4382 /* 4383 * OK, try to get the list of private ioctls. 4384 */ 4385 priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args)); 4386 if (priv == NULL) { 4387 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4388 "malloc: %s", pcap_strerror(errno)); 4389 return PCAP_ERROR; 4390 } 4391 ireq.u.data.pointer = (void *)priv; 4392 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { 4393 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4394 "%s: SIOCGIWPRIV: %s", device, 4395 pcap_strerror(errno)); 4396 free(priv); 4397 return PCAP_ERROR; 4398 } 4399 4400 /* 4401 * Look for private ioctls to turn monitor mode on or, if 4402 * monitor mode is on, to set the header type. 4403 */ 4404 for (i = 0; i < ireq.u.data.length; i++) { 4405 if (strcmp(priv[i].name, "monitor_type") == 0) { 4406 /* 4407 * Hostap driver, use this one. 4408 * Set monitor mode first. 4409 * You can set it to 0 to get DLT_IEEE80211, 4410 * 1 to get DLT_PRISM, 2 to get 4411 * DLT_IEEE80211_RADIO_AVS, and, with more 4412 * recent versions of the driver, 3 to get 4413 * DLT_IEEE80211_RADIO. 4414 */ 4415 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4416 break; 4417 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4418 break; 4419 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4420 break; 4421 montype = MONITOR_HOSTAP; 4422 cmd = priv[i].cmd; 4423 break; 4424 } 4425 if (strcmp(priv[i].name, "set_prismhdr") == 0) { 4426 /* 4427 * Prism54 driver, use this one. 4428 * Set monitor mode first. 4429 * You can set it to 2 to get DLT_IEEE80211 4430 * or 3 or get DLT_PRISM. 4431 */ 4432 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4433 break; 4434 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4435 break; 4436 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4437 break; 4438 montype = MONITOR_PRISM54; 4439 cmd = priv[i].cmd; 4440 break; 4441 } 4442 if (strcmp(priv[i].name, "forceprismheader") == 0) { 4443 /* 4444 * RT2570 driver, use this one. 4445 * Do this after turning monitor mode on. 4446 * You can set it to 1 to get DLT_PRISM or 2 4447 * to get DLT_IEEE80211. 4448 */ 4449 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4450 break; 4451 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4452 break; 4453 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4454 break; 4455 montype = MONITOR_RT2570; 4456 cmd = priv[i].cmd; 4457 break; 4458 } 4459 if (strcmp(priv[i].name, "forceprism") == 0) { 4460 /* 4461 * RT73 driver, use this one. 4462 * Do this after turning monitor mode on. 4463 * Its argument is a *string*; you can 4464 * set it to "1" to get DLT_PRISM or "2" 4465 * to get DLT_IEEE80211. 4466 */ 4467 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR) 4468 break; 4469 if (priv[i].set_args & IW_PRIV_SIZE_FIXED) 4470 break; 4471 montype = MONITOR_RT73; 4472 cmd = priv[i].cmd; 4473 break; 4474 } 4475 if (strcmp(priv[i].name, "prismhdr") == 0) { 4476 /* 4477 * One of the RTL8xxx drivers, use this one. 4478 * It can only be done after monitor mode 4479 * has been turned on. You can set it to 1 4480 * to get DLT_PRISM or 0 to get DLT_IEEE80211. 4481 */ 4482 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4483 break; 4484 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4485 break; 4486 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4487 break; 4488 montype = MONITOR_RTL8XXX; 4489 cmd = priv[i].cmd; 4490 break; 4491 } 4492 if (strcmp(priv[i].name, "rfmontx") == 0) { 4493 /* 4494 * RT2500 or RT61 driver, use this one. 4495 * It has one one-byte parameter; set 4496 * u.data.length to 1 and u.data.pointer to 4497 * point to the parameter. 4498 * It doesn't itself turn monitor mode on. 4499 * You can set it to 1 to allow transmitting 4500 * in monitor mode(?) and get DLT_IEEE80211, 4501 * or set it to 0 to disallow transmitting in 4502 * monitor mode(?) and get DLT_PRISM. 4503 */ 4504 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4505 break; 4506 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2) 4507 break; 4508 montype = MONITOR_RT2500; 4509 cmd = priv[i].cmd; 4510 break; 4511 } 4512 if (strcmp(priv[i].name, "monitor") == 0) { 4513 /* 4514 * Either ACX100 or hostap, use this one. 4515 * It turns monitor mode on. 4516 * If it takes two arguments, it's ACX100; 4517 * the first argument is 1 for DLT_PRISM 4518 * or 2 for DLT_IEEE80211, and the second 4519 * argument is the channel on which to 4520 * run. If it takes one argument, it's 4521 * HostAP, and the argument is 2 for 4522 * DLT_IEEE80211 and 3 for DLT_PRISM. 4523 * 4524 * If we see this, we don't quit, as this 4525 * might be a version of the hostap driver 4526 * that also supports "monitor_type". 4527 */ 4528 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4529 break; 4530 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4531 break; 4532 switch (priv[i].set_args & IW_PRIV_SIZE_MASK) { 4533 4534 case 1: 4535 montype = MONITOR_PRISM; 4536 cmd = priv[i].cmd; 4537 break; 4538 4539 case 2: 4540 montype = MONITOR_ACX100; 4541 cmd = priv[i].cmd; 4542 break; 4543 4544 default: 4545 break; 4546 } 4547 } 4548 } 4549 free(priv); 4550 } 4551 4552 /* 4553 * XXX - ipw3945? islism? 4554 */ 4555 4556 /* 4557 * Get the old mode. 4558 */ 4559 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4560 sizeof ireq.ifr_ifrn.ifrn_name); 4561 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4562 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) { 4563 /* 4564 * We probably won't be able to set the mode, either. 4565 */ 4566 return PCAP_ERROR_RFMON_NOTSUP; 4567 } 4568 4569 /* 4570 * Is it currently in monitor mode? 4571 */ 4572 if (ireq.u.mode == IW_MODE_MONITOR) { 4573 /* 4574 * Yes. Just leave things as they are. 4575 * We don't offer multiple link-layer types, as 4576 * changing the link-layer type out from under 4577 * somebody else capturing in monitor mode would 4578 * be considered rude. 4579 */ 4580 return 1; 4581 } 4582 /* 4583 * No. We have to put the adapter into rfmon mode. 4584 */ 4585 4586 /* 4587 * If we haven't already done so, arrange to have 4588 * "pcap_close_all()" called when we exit. 4589 */ 4590 if (!pcap_do_addexit(handle)) { 4591 /* 4592 * "atexit()" failed; don't put the interface 4593 * in rfmon mode, just give up. 4594 */ 4595 return PCAP_ERROR_RFMON_NOTSUP; 4596 } 4597 4598 /* 4599 * Save the old mode. 4600 */ 4601 handle->md.oldmode = ireq.u.mode; 4602 4603 /* 4604 * Put the adapter in rfmon mode. How we do this depends 4605 * on whether we have a special private ioctl or not. 4606 */ 4607 if (montype == MONITOR_PRISM) { 4608 /* 4609 * We have the "monitor" private ioctl, but none of 4610 * the other private ioctls. Use this, and select 4611 * the Prism header. 4612 * 4613 * If it fails, just fall back on SIOCSIWMODE. 4614 */ 4615 memset(&ireq, 0, sizeof ireq); 4616 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4617 sizeof ireq.ifr_ifrn.ifrn_name); 4618 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4619 ireq.u.data.length = 1; /* 1 argument */ 4620 args[0] = 3; /* request Prism header */ 4621 memcpy(ireq.u.name, args, IFNAMSIZ); 4622 if (ioctl(sock_fd, cmd, &ireq) != -1) { 4623 /* 4624 * Success. 4625 * Note that we have to put the old mode back 4626 * when we close the device. 4627 */ 4628 handle->md.must_do_on_close |= MUST_CLEAR_RFMON; 4629 4630 /* 4631 * Add this to the list of pcaps to close 4632 * when we exit. 4633 */ 4634 pcap_add_to_pcaps_to_close(handle); 4635 4636 return 1; 4637 } 4638 4639 /* 4640 * Failure. Fall back on SIOCSIWMODE. 4641 */ 4642 } 4643 4644 /* 4645 * First, take the interface down if it's up; otherwise, we 4646 * might get EBUSY. 4647 */ 4648 memset(&ifr, 0, sizeof(ifr)); 4649 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 4650 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { 4651 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4652 "%s: Can't get flags: %s", device, strerror(errno)); 4653 return PCAP_ERROR; 4654 } 4655 oldflags = 0; 4656 if (ifr.ifr_flags & IFF_UP) { 4657 oldflags = ifr.ifr_flags; 4658 ifr.ifr_flags &= ~IFF_UP; 4659 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4660 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4661 "%s: Can't set flags: %s", device, strerror(errno)); 4662 return PCAP_ERROR; 4663 } 4664 } 4665 4666 /* 4667 * Then turn monitor mode on. 4668 */ 4669 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4670 sizeof ireq.ifr_ifrn.ifrn_name); 4671 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4672 ireq.u.mode = IW_MODE_MONITOR; 4673 if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) { 4674 /* 4675 * Scientist, you've failed. 4676 * Bring the interface back up if we shut it down. 4677 */ 4678 ifr.ifr_flags = oldflags; 4679 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4680 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4681 "%s: Can't set flags: %s", device, strerror(errno)); 4682 return PCAP_ERROR; 4683 } 4684 return PCAP_ERROR_RFMON_NOTSUP; 4685 } 4686 4687 /* 4688 * XXX - airmon-ng does "iwconfig {if} key off" after setting 4689 * monitor mode and setting the channel, and then does 4690 * "iwconfig up". 4691 */ 4692 4693 /* 4694 * Now select the appropriate radio header. 4695 */ 4696 switch (montype) { 4697 4698 case MONITOR_WEXT: 4699 /* 4700 * We don't have any private ioctl to set the header. 4701 */ 4702 break; 4703 4704 case MONITOR_HOSTAP: 4705 /* 4706 * Try to select the radiotap header. 4707 */ 4708 memset(&ireq, 0, sizeof ireq); 4709 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4710 sizeof ireq.ifr_ifrn.ifrn_name); 4711 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4712 args[0] = 3; /* request radiotap header */ 4713 memcpy(ireq.u.name, args, sizeof (int)); 4714 if (ioctl(sock_fd, cmd, &ireq) != -1) 4715 break; /* success */ 4716 4717 /* 4718 * That failed. Try to select the AVS header. 4719 */ 4720 memset(&ireq, 0, sizeof ireq); 4721 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4722 sizeof ireq.ifr_ifrn.ifrn_name); 4723 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4724 args[0] = 2; /* request AVS header */ 4725 memcpy(ireq.u.name, args, sizeof (int)); 4726 if (ioctl(sock_fd, cmd, &ireq) != -1) 4727 break; /* success */ 4728 4729 /* 4730 * That failed. Try to select the Prism header. 4731 */ 4732 memset(&ireq, 0, sizeof ireq); 4733 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4734 sizeof ireq.ifr_ifrn.ifrn_name); 4735 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4736 args[0] = 1; /* request Prism header */ 4737 memcpy(ireq.u.name, args, sizeof (int)); 4738 ioctl(sock_fd, cmd, &ireq); 4739 break; 4740 4741 case MONITOR_PRISM: 4742 /* 4743 * The private ioctl failed. 4744 */ 4745 break; 4746 4747 case MONITOR_PRISM54: 4748 /* 4749 * Select the Prism header. 4750 */ 4751 memset(&ireq, 0, sizeof ireq); 4752 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4753 sizeof ireq.ifr_ifrn.ifrn_name); 4754 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4755 args[0] = 3; /* request Prism header */ 4756 memcpy(ireq.u.name, args, sizeof (int)); 4757 ioctl(sock_fd, cmd, &ireq); 4758 break; 4759 4760 case MONITOR_ACX100: 4761 /* 4762 * Get the current channel. 4763 */ 4764 memset(&ireq, 0, sizeof ireq); 4765 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4766 sizeof ireq.ifr_ifrn.ifrn_name); 4767 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4768 if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) { 4769 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4770 "%s: SIOCGIWFREQ: %s", device, 4771 pcap_strerror(errno)); 4772 return PCAP_ERROR; 4773 } 4774 channel = ireq.u.freq.m; 4775 4776 /* 4777 * Select the Prism header, and set the channel to the 4778 * current value. 4779 */ 4780 memset(&ireq, 0, sizeof ireq); 4781 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4782 sizeof ireq.ifr_ifrn.ifrn_name); 4783 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4784 args[0] = 1; /* request Prism header */ 4785 args[1] = channel; /* set channel */ 4786 memcpy(ireq.u.name, args, 2*sizeof (int)); 4787 ioctl(sock_fd, cmd, &ireq); 4788 break; 4789 4790 case MONITOR_RT2500: 4791 /* 4792 * Disallow transmission - that turns on the 4793 * Prism header. 4794 */ 4795 memset(&ireq, 0, sizeof ireq); 4796 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4797 sizeof ireq.ifr_ifrn.ifrn_name); 4798 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4799 args[0] = 0; /* disallow transmitting */ 4800 memcpy(ireq.u.name, args, sizeof (int)); 4801 ioctl(sock_fd, cmd, &ireq); 4802 break; 4803 4804 case MONITOR_RT2570: 4805 /* 4806 * Force the Prism header. 4807 */ 4808 memset(&ireq, 0, sizeof ireq); 4809 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4810 sizeof ireq.ifr_ifrn.ifrn_name); 4811 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4812 args[0] = 1; /* request Prism header */ 4813 memcpy(ireq.u.name, args, sizeof (int)); 4814 ioctl(sock_fd, cmd, &ireq); 4815 break; 4816 4817 case MONITOR_RT73: 4818 /* 4819 * Force the Prism header. 4820 */ 4821 memset(&ireq, 0, sizeof ireq); 4822 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4823 sizeof ireq.ifr_ifrn.ifrn_name); 4824 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4825 ireq.u.data.length = 1; /* 1 argument */ 4826 ireq.u.data.pointer = "1"; 4827 ireq.u.data.flags = 0; 4828 ioctl(sock_fd, cmd, &ireq); 4829 break; 4830 4831 case MONITOR_RTL8XXX: 4832 /* 4833 * Force the Prism header. 4834 */ 4835 memset(&ireq, 0, sizeof ireq); 4836 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4837 sizeof ireq.ifr_ifrn.ifrn_name); 4838 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4839 args[0] = 1; /* request Prism header */ 4840 memcpy(ireq.u.name, args, sizeof (int)); 4841 ioctl(sock_fd, cmd, &ireq); 4842 break; 4843 } 4844 4845 /* 4846 * Now bring the interface back up if we brought it down. 4847 */ 4848 if (oldflags != 0) { 4849 ifr.ifr_flags = oldflags; 4850 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4851 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4852 "%s: Can't set flags: %s", device, strerror(errno)); 4853 4854 /* 4855 * At least try to restore the old mode on the 4856 * interface. 4857 */ 4858 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { 4859 /* 4860 * Scientist, you've failed. 4861 */ 4862 fprintf(stderr, 4863 "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n" 4864 "Please adjust manually.\n", 4865 strerror(errno)); 4866 } 4867 return PCAP_ERROR; 4868 } 4869 } 4870 4871 /* 4872 * Note that we have to put the old mode back when we 4873 * close the device. 4874 */ 4875 handle->md.must_do_on_close |= MUST_CLEAR_RFMON; 4876 4877 /* 4878 * Add this to the list of pcaps to close when we exit. 4879 */ 4880 pcap_add_to_pcaps_to_close(handle); 4881 4882 return 1; 4883 } 4884 #endif /* IW_MODE_MONITOR */ 4885 4886 /* 4887 * Try various mechanisms to enter monitor mode. 4888 */ 4889 static int 4890 enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) 4891 { 4892 #if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) 4893 int ret; 4894 #endif 4895 4896 #ifdef HAVE_LIBNL 4897 ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); 4898 if (ret < 0) 4899 return ret; /* error attempting to do so */ 4900 if (ret == 1) 4901 return 1; /* success */ 4902 #endif /* HAVE_LIBNL */ 4903 4904 #ifdef IW_MODE_MONITOR 4905 ret = enter_rfmon_mode_wext(handle, sock_fd, device); 4906 if (ret < 0) 4907 return ret; /* error attempting to do so */ 4908 if (ret == 1) 4909 return 1; /* success */ 4910 #endif /* IW_MODE_MONITOR */ 4911 4912 /* 4913 * Either none of the mechanisms we know about work or none 4914 * of those mechanisms are available, so we can't do monitor 4915 * mode. 4916 */ 4917 return 0; 4918 } 4919 4920 /* 4921 * Find out if we have any form of fragmentation/reassembly offloading. 4922 * 4923 * We do so using SIOCETHTOOL checking for various types of offloading; 4924 * if SIOCETHTOOL isn't defined, or we don't have any #defines for any 4925 * of the types of offloading, there's nothing we can do to check, so 4926 * we just say "no, we don't". 4927 */ 4928 #if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO)) 4929 static int 4930 iface_ethtool_ioctl(pcap_t *handle, int cmd, const char *cmdname) 4931 { 4932 struct ifreq ifr; 4933 struct ethtool_value eval; 4934 4935 memset(&ifr, 0, sizeof(ifr)); 4936 strncpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name)); 4937 eval.cmd = cmd; 4938 ifr.ifr_data = (caddr_t)&eval; 4939 if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) { 4940 if (errno == EOPNOTSUPP) { 4941 /* 4942 * OK, let's just return 0, which, in our 4943 * case, either means "no, what we're asking 4944 * about is not enabled" or "all the flags 4945 * are clear (i.e., nothing is enabled)". 4946 */ 4947 return 0; 4948 } 4949 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4950 "%s: SIOETHTOOL(%s) ioctl failed: %s", handle->opt.source, 4951 cmdname, strerror(errno)); 4952 return -1; 4953 } 4954 return eval.data; 4955 } 4956 4957 static int 4958 iface_get_offload(pcap_t *handle) 4959 { 4960 int ret; 4961 4962 #ifdef ETHTOOL_GTSO 4963 ret = iface_ethtool_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO"); 4964 if (ret == -1) 4965 return -1; 4966 if (ret) 4967 return 1; /* TCP segmentation offloading on */ 4968 #endif 4969 4970 #ifdef ETHTOOL_GUFO 4971 ret = iface_ethtool_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO"); 4972 if (ret == -1) 4973 return -1; 4974 if (ret) 4975 return 1; /* UDP fragmentation offloading on */ 4976 #endif 4977 4978 #ifdef ETHTOOL_GGSO 4979 /* 4980 * XXX - will this cause large unsegmented packets to be 4981 * handed to PF_PACKET sockets on transmission? If not, 4982 * this need not be checked. 4983 */ 4984 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO"); 4985 if (ret == -1) 4986 return -1; 4987 if (ret) 4988 return 1; /* generic segmentation offloading on */ 4989 #endif 4990 4991 #ifdef ETHTOOL_GFLAGS 4992 ret = iface_ethtool_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS"); 4993 if (ret == -1) 4994 return -1; 4995 if (ret & ETH_FLAG_LRO) 4996 return 1; /* large receive offloading on */ 4997 #endif 4998 4999 #ifdef ETHTOOL_GGRO 5000 /* 5001 * XXX - will this cause large reassembled packets to be 5002 * handed to PF_PACKET sockets on receipt? If not, 5003 * this need not be checked. 5004 */ 5005 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO"); 5006 if (ret == -1) 5007 return -1; 5008 if (ret) 5009 return 1; /* generic (large) receive offloading on */ 5010 #endif 5011 5012 return 0; 5013 } 5014 #else /* SIOCETHTOOL */ 5015 static int 5016 iface_get_offload(pcap_t *handle _U_) 5017 { 5018 /* 5019 * XXX - do we need to get this information if we don't 5020 * have the ethtool ioctls? If so, how do we do that? 5021 */ 5022 return 0; 5023 } 5024 #endif /* SIOCETHTOOL */ 5025 5026 #endif /* HAVE_PF_PACKET_SOCKETS */ 5027 5028 /* ===== Functions to interface to the older kernels ================== */ 5029 5030 /* 5031 * Try to open a packet socket using the old kernel interface. 5032 * Returns 1 on success and a PCAP_ERROR_ value on an error. 5033 */ 5034 static int 5035 activate_old(pcap_t *handle) 5036 { 5037 int arptype; 5038 struct ifreq ifr; 5039 const char *device = handle->opt.source; 5040 struct utsname utsname; 5041 int mtu; 5042 5043 /* Open the socket */ 5044 5045 handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); 5046 if (handle->fd == -1) { 5047 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5048 "socket: %s", pcap_strerror(errno)); 5049 if (errno == EPERM || errno == EACCES) { 5050 /* 5051 * You don't have permission to open the 5052 * socket. 5053 */ 5054 return PCAP_ERROR_PERM_DENIED; 5055 } else { 5056 /* 5057 * Other error. 5058 */ 5059 return PCAP_ERROR; 5060 } 5061 } 5062 5063 /* It worked - we are using the old interface */ 5064 handle->md.sock_packet = 1; 5065 5066 /* ...which means we get the link-layer header. */ 5067 handle->md.cooked = 0; 5068 5069 /* Bind to the given device */ 5070 5071 if (strcmp(device, "any") == 0) { 5072 strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems", 5073 PCAP_ERRBUF_SIZE); 5074 return PCAP_ERROR; 5075 } 5076 if (iface_bind_old(handle->fd, device, handle->errbuf) == -1) 5077 return PCAP_ERROR; 5078 5079 /* 5080 * Try to get the link-layer type. 5081 */ 5082 arptype = iface_get_arptype(handle->fd, device, handle->errbuf); 5083 if (arptype < 0) 5084 return PCAP_ERROR; 5085 5086 /* 5087 * Try to find the DLT_ type corresponding to that 5088 * link-layer type. 5089 */ 5090 map_arphrd_to_dlt(handle, arptype, 0); 5091 if (handle->linktype == -1) { 5092 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5093 "unknown arptype %d", arptype); 5094 return PCAP_ERROR; 5095 } 5096 5097 /* Go to promisc mode if requested */ 5098 5099 if (handle->opt.promisc) { 5100 memset(&ifr, 0, sizeof(ifr)); 5101 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5102 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { 5103 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5104 "SIOCGIFFLAGS: %s", pcap_strerror(errno)); 5105 return PCAP_ERROR; 5106 } 5107 if ((ifr.ifr_flags & IFF_PROMISC) == 0) { 5108 /* 5109 * Promiscuous mode isn't currently on, 5110 * so turn it on, and remember that 5111 * we should turn it off when the 5112 * pcap_t is closed. 5113 */ 5114 5115 /* 5116 * If we haven't already done so, arrange 5117 * to have "pcap_close_all()" called when 5118 * we exit. 5119 */ 5120 if (!pcap_do_addexit(handle)) { 5121 /* 5122 * "atexit()" failed; don't put 5123 * the interface in promiscuous 5124 * mode, just give up. 5125 */ 5126 return PCAP_ERROR; 5127 } 5128 5129 ifr.ifr_flags |= IFF_PROMISC; 5130 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { 5131 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5132 "SIOCSIFFLAGS: %s", 5133 pcap_strerror(errno)); 5134 return PCAP_ERROR; 5135 } 5136 handle->md.must_do_on_close |= MUST_CLEAR_PROMISC; 5137 5138 /* 5139 * Add this to the list of pcaps 5140 * to close when we exit. 5141 */ 5142 pcap_add_to_pcaps_to_close(handle); 5143 } 5144 } 5145 5146 /* 5147 * Compute the buffer size. 5148 * 5149 * We're using SOCK_PACKET, so this might be a 2.0[.x] 5150 * kernel, and might require special handling - check. 5151 */ 5152 if (uname(&utsname) < 0 || 5153 strncmp(utsname.release, "2.0", 3) == 0) { 5154 /* 5155 * Either we couldn't find out what kernel release 5156 * this is, or it's a 2.0[.x] kernel. 5157 * 5158 * In the 2.0[.x] kernel, a "recvfrom()" on 5159 * a SOCK_PACKET socket, with MSG_TRUNC set, will 5160 * return the number of bytes read, so if we pass 5161 * a length based on the snapshot length, it'll 5162 * return the number of bytes from the packet 5163 * copied to userland, not the actual length 5164 * of the packet. 5165 * 5166 * This means that, for example, the IP dissector 5167 * in tcpdump will get handed a packet length less 5168 * than the length in the IP header, and will 5169 * complain about "truncated-ip". 5170 * 5171 * So we don't bother trying to copy from the 5172 * kernel only the bytes in which we're interested, 5173 * but instead copy them all, just as the older 5174 * versions of libpcap for Linux did. 5175 * 5176 * The buffer therefore needs to be big enough to 5177 * hold the largest packet we can get from this 5178 * device. Unfortunately, we can't get the MRU 5179 * of the network; we can only get the MTU. The 5180 * MTU may be too small, in which case a packet larger 5181 * than the buffer size will be truncated *and* we 5182 * won't get the actual packet size. 5183 * 5184 * However, if the snapshot length is larger than 5185 * the buffer size based on the MTU, we use the 5186 * snapshot length as the buffer size, instead; 5187 * this means that with a sufficiently large snapshot 5188 * length we won't artificially truncate packets 5189 * to the MTU-based size. 5190 * 5191 * This mess just one of many problems with packet 5192 * capture on 2.0[.x] kernels; you really want a 5193 * 2.2[.x] or later kernel if you want packet capture 5194 * to work well. 5195 */ 5196 mtu = iface_get_mtu(handle->fd, device, handle->errbuf); 5197 if (mtu == -1) 5198 return PCAP_ERROR; 5199 handle->bufsize = MAX_LINKHEADER_SIZE + mtu; 5200 if (handle->bufsize < handle->snapshot) 5201 handle->bufsize = handle->snapshot; 5202 } else { 5203 /* 5204 * This is a 2.2[.x] or later kernel. 5205 * 5206 * We can safely pass "recvfrom()" a byte count 5207 * based on the snapshot length. 5208 */ 5209 handle->bufsize = handle->snapshot; 5210 } 5211 5212 /* 5213 * Default value for offset to align link-layer payload 5214 * on a 4-byte boundary. 5215 */ 5216 handle->offset = 0; 5217 5218 return 1; 5219 } 5220 5221 /* 5222 * Bind the socket associated with FD to the given device using the 5223 * interface of the old kernels. 5224 */ 5225 static int 5226 iface_bind_old(int fd, const char *device, char *ebuf) 5227 { 5228 struct sockaddr saddr; 5229 int err; 5230 socklen_t errlen = sizeof(err); 5231 5232 memset(&saddr, 0, sizeof(saddr)); 5233 strncpy(saddr.sa_data, device, sizeof(saddr.sa_data)); 5234 if (bind(fd, &saddr, sizeof(saddr)) == -1) { 5235 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5236 "bind: %s", pcap_strerror(errno)); 5237 return -1; 5238 } 5239 5240 /* Any pending errors, e.g., network is down? */ 5241 5242 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { 5243 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5244 "getsockopt: %s", pcap_strerror(errno)); 5245 return -1; 5246 } 5247 5248 if (err > 0) { 5249 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5250 "bind: %s", pcap_strerror(err)); 5251 return -1; 5252 } 5253 5254 return 0; 5255 } 5256 5257 5258 /* ===== System calls available on all supported kernels ============== */ 5259 5260 /* 5261 * Query the kernel for the MTU of the given interface. 5262 */ 5263 static int 5264 iface_get_mtu(int fd, const char *device, char *ebuf) 5265 { 5266 struct ifreq ifr; 5267 5268 if (!device) 5269 return BIGGER_THAN_ALL_MTUS; 5270 5271 memset(&ifr, 0, sizeof(ifr)); 5272 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5273 5274 if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { 5275 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5276 "SIOCGIFMTU: %s", pcap_strerror(errno)); 5277 return -1; 5278 } 5279 5280 return ifr.ifr_mtu; 5281 } 5282 5283 /* 5284 * Get the hardware type of the given interface as ARPHRD_xxx constant. 5285 */ 5286 static int 5287 iface_get_arptype(int fd, const char *device, char *ebuf) 5288 { 5289 struct ifreq ifr; 5290 5291 memset(&ifr, 0, sizeof(ifr)); 5292 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5293 5294 if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { 5295 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5296 "SIOCGIFHWADDR: %s", pcap_strerror(errno)); 5297 if (errno == ENODEV) { 5298 /* 5299 * No such device. 5300 */ 5301 return PCAP_ERROR_NO_SUCH_DEVICE; 5302 } 5303 return PCAP_ERROR; 5304 } 5305 5306 return ifr.ifr_hwaddr.sa_family; 5307 } 5308 5309 #ifdef SO_ATTACH_FILTER 5310 static int 5311 fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) 5312 { 5313 size_t prog_size; 5314 register int i; 5315 register struct bpf_insn *p; 5316 struct bpf_insn *f; 5317 int len; 5318 5319 /* 5320 * Make a copy of the filter, and modify that copy if 5321 * necessary. 5322 */ 5323 prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len; 5324 len = handle->fcode.bf_len; 5325 f = (struct bpf_insn *)malloc(prog_size); 5326 if (f == NULL) { 5327 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5328 "malloc: %s", pcap_strerror(errno)); 5329 return -1; 5330 } 5331 memcpy(f, handle->fcode.bf_insns, prog_size); 5332 fcode->len = len; 5333 fcode->filter = (struct sock_filter *) f; 5334 5335 for (i = 0; i < len; ++i) { 5336 p = &f[i]; 5337 /* 5338 * What type of instruction is this? 5339 */ 5340 switch (BPF_CLASS(p->code)) { 5341 5342 case BPF_RET: 5343 /* 5344 * It's a return instruction; are we capturing 5345 * in memory-mapped mode? 5346 */ 5347 if (!is_mmapped) { 5348 /* 5349 * No; is the snapshot length a constant, 5350 * rather than the contents of the 5351 * accumulator? 5352 */ 5353 if (BPF_MODE(p->code) == BPF_K) { 5354 /* 5355 * Yes - if the value to be returned, 5356 * i.e. the snapshot length, is 5357 * anything other than 0, make it 5358 * 65535, so that the packet is 5359 * truncated by "recvfrom()", 5360 * not by the filter. 5361 * 5362 * XXX - there's nothing we can 5363 * easily do if it's getting the 5364 * value from the accumulator; we'd 5365 * have to insert code to force 5366 * non-zero values to be 65535. 5367 */ 5368 if (p->k != 0) 5369 p->k = 65535; 5370 } 5371 } 5372 break; 5373 5374 case BPF_LD: 5375 case BPF_LDX: 5376 /* 5377 * It's a load instruction; is it loading 5378 * from the packet? 5379 */ 5380 switch (BPF_MODE(p->code)) { 5381 5382 case BPF_ABS: 5383 case BPF_IND: 5384 case BPF_MSH: 5385 /* 5386 * Yes; are we in cooked mode? 5387 */ 5388 if (handle->md.cooked) { 5389 /* 5390 * Yes, so we need to fix this 5391 * instruction. 5392 */ 5393 if (fix_offset(p) < 0) { 5394 /* 5395 * We failed to do so. 5396 * Return 0, so our caller 5397 * knows to punt to userland. 5398 */ 5399 return 0; 5400 } 5401 } 5402 break; 5403 } 5404 break; 5405 } 5406 } 5407 return 1; /* we succeeded */ 5408 } 5409 5410 static int 5411 fix_offset(struct bpf_insn *p) 5412 { 5413 /* 5414 * What's the offset? 5415 */ 5416 if (p->k >= SLL_HDR_LEN) { 5417 /* 5418 * It's within the link-layer payload; that starts at an 5419 * offset of 0, as far as the kernel packet filter is 5420 * concerned, so subtract the length of the link-layer 5421 * header. 5422 */ 5423 p->k -= SLL_HDR_LEN; 5424 } else if (p->k == 0) { 5425 /* 5426 * It's the packet type field; map it to the special magic 5427 * kernel offset for that field. 5428 */ 5429 p->k = SKF_AD_OFF + SKF_AD_PKTTYPE; 5430 } else if (p->k == 14) { 5431 /* 5432 * It's the protocol field; map it to the special magic 5433 * kernel offset for that field. 5434 */ 5435 p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; 5436 } else if ((bpf_int32)(p->k) > 0) { 5437 /* 5438 * It's within the header, but it's not one of those 5439 * fields; we can't do that in the kernel, so punt 5440 * to userland. 5441 */ 5442 return -1; 5443 } 5444 return 0; 5445 } 5446 5447 static int 5448 set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode) 5449 { 5450 int total_filter_on = 0; 5451 int save_mode; 5452 int ret; 5453 int save_errno; 5454 5455 /* 5456 * The socket filter code doesn't discard all packets queued 5457 * up on the socket when the filter is changed; this means 5458 * that packets that don't match the new filter may show up 5459 * after the new filter is put onto the socket, if those 5460 * packets haven't yet been read. 5461 * 5462 * This means, for example, that if you do a tcpdump capture 5463 * with a filter, the first few packets in the capture might 5464 * be packets that wouldn't have passed the filter. 5465 * 5466 * We therefore discard all packets queued up on the socket 5467 * when setting a kernel filter. (This isn't an issue for 5468 * userland filters, as the userland filtering is done after 5469 * packets are queued up.) 5470 * 5471 * To flush those packets, we put the socket in read-only mode, 5472 * and read packets from the socket until there are no more to 5473 * read. 5474 * 5475 * In order to keep that from being an infinite loop - i.e., 5476 * to keep more packets from arriving while we're draining 5477 * the queue - we put the "total filter", which is a filter 5478 * that rejects all packets, onto the socket before draining 5479 * the queue. 5480 * 5481 * This code deliberately ignores any errors, so that you may 5482 * get bogus packets if an error occurs, rather than having 5483 * the filtering done in userland even if it could have been 5484 * done in the kernel. 5485 */ 5486 if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, 5487 &total_fcode, sizeof(total_fcode)) == 0) { 5488 char drain[1]; 5489 5490 /* 5491 * Note that we've put the total filter onto the socket. 5492 */ 5493 total_filter_on = 1; 5494 5495 /* 5496 * Save the socket's current mode, and put it in 5497 * non-blocking mode; we drain it by reading packets 5498 * until we get an error (which is normally a 5499 * "nothing more to be read" error). 5500 */ 5501 save_mode = fcntl(handle->fd, F_GETFL, 0); 5502 if (save_mode != -1 && 5503 fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) { 5504 while (recv(handle->fd, &drain, sizeof drain, 5505 MSG_TRUNC) >= 0) 5506 ; 5507 save_errno = errno; 5508 fcntl(handle->fd, F_SETFL, save_mode); 5509 if (save_errno != EAGAIN) { 5510 /* Fatal error */ 5511 reset_kernel_filter(handle); 5512 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5513 "recv: %s", pcap_strerror(save_errno)); 5514 return -2; 5515 } 5516 } 5517 } 5518 5519 /* 5520 * Now attach the new filter. 5521 */ 5522 ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, 5523 fcode, sizeof(*fcode)); 5524 if (ret == -1 && total_filter_on) { 5525 /* 5526 * Well, we couldn't set that filter on the socket, 5527 * but we could set the total filter on the socket. 5528 * 5529 * This could, for example, mean that the filter was 5530 * too big to put into the kernel, so we'll have to 5531 * filter in userland; in any case, we'll be doing 5532 * filtering in userland, so we need to remove the 5533 * total filter so we see packets. 5534 */ 5535 save_errno = errno; 5536 5537 /* 5538 * XXX - if this fails, we're really screwed; 5539 * we have the total filter on the socket, 5540 * and it won't come off. What do we do then? 5541 */ 5542 reset_kernel_filter(handle); 5543 5544 errno = save_errno; 5545 } 5546 return ret; 5547 } 5548 5549 static int 5550 reset_kernel_filter(pcap_t *handle) 5551 { 5552 /* 5553 * setsockopt() barfs unless it get a dummy parameter. 5554 * valgrind whines unless the value is initialized, 5555 * as it has no idea that setsockopt() ignores its 5556 * parameter. 5557 */ 5558 int dummy = 0; 5559 5560 return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, 5561 &dummy, sizeof(dummy)); 5562 } 5563 #endif 5564