1 /* $OpenBSD: pf.c,v 1.11 2004/05/08 20:23:21 canacar Exp $ */ 2 3 /* 4 * Copyright (c) 1993-95 Mats O Jansson. All rights reserved. 5 * Copyright (c) 1990 The Regents of the University of California. 6 * All rights reserved. 7 * 8 * This code is partly derived from rarpd. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #ifndef LINT 32 static const char rcsid[] = 33 "$OpenBSD: pf.c,v 1.11 2004/05/08 20:23:21 canacar Exp $"; 34 #endif 35 36 #include <stdio.h> 37 #include <unistd.h> 38 #include <sys/types.h> 39 #include <sys/time.h> 40 #include <sys/ioctl.h> 41 #include <sys/file.h> 42 #include <sys/socket.h> 43 #include <sys/uio.h> 44 #include <net/if.h> 45 46 #include <net/bpf.h> 47 #include <sys/errno.h> 48 49 #include <netinet/in.h> 50 #include <netinet/if_ether.h> 51 52 #include <netdb.h> 53 #include <ctype.h> 54 #include <string.h> 55 #include <err.h> 56 57 #include <syslog.h> 58 59 #include "common/mopdef.h" 60 61 /* 62 * Variables 63 */ 64 65 extern int promisc; 66 67 /* 68 * Return information to device.c how to open device. 69 * In this case the driver can handle both Ethernet type II and 70 * IEEE 802.3 frames (SNAP) in a single pfOpen. 71 */ 72 73 int 74 pfTrans(char *interface) 75 { 76 return (TRANS_ETHER + TRANS_8023 + TRANS_AND); 77 } 78 79 /* 80 * Open and initialize packet filter. 81 */ 82 int 83 pfInit(char *interface, int mode, u_short protocol, int typ) 84 { 85 int fd; 86 int n = 0; 87 char device[sizeof "/dev/bpf000"]; 88 struct ifreq ifr; 89 u_int dlt; 90 int immediate; 91 92 static struct bpf_insn insns[] = { 93 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 94 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x4711, 4, 0), 95 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 96 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x4711, 0, 3), 97 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 14), 98 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0xaaaa, 0, 1), 99 BPF_STMT(BPF_RET | BPF_K, 1520), 100 BPF_STMT(BPF_RET | BPF_K, 0), 101 }; 102 static struct bpf_program filter = { 103 sizeof insns / sizeof(insns[0]), 104 insns 105 }; 106 107 /* Go through all the minors and find one that isn't in use. */ 108 do { 109 snprintf(device, sizeof device, "/dev/bpf%d", n++); 110 fd = open(device, mode); 111 } while (fd < 0 && errno == EBUSY); 112 113 if (fd < 0) { 114 syslog(LOG_ERR,"pfInit: open bpf %m"); 115 return (-1); 116 } 117 118 /* Set immediate mode so packets are processed as they arrive. */ 119 immediate = 1; 120 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 121 syslog(LOG_ERR,"pfInit: BIOCIMMEDIATE: %m"); 122 return (-1); 123 } 124 strncpy(ifr.ifr_name, interface, sizeof ifr.ifr_name); 125 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 126 syslog(LOG_ERR,"pfInit: BIOCSETIF: %m"); 127 return (-1); 128 } 129 /* Check that the data link layer is an Ethernet; this code won't work 130 * with anything else. */ 131 if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) < 0) { 132 syslog(LOG_ERR,"pfInit: BIOCGDLT: %m"); 133 return (-1); 134 } 135 if (dlt != DLT_EN10MB) { 136 syslog(LOG_ERR,"pfInit: %s is not ethernet", device); 137 return (-1); 138 } 139 if (promisc) 140 /* Set promiscuous mode. */ 141 if (ioctl(fd, BIOCPROMISC, (caddr_t)0) < 0) { 142 syslog(LOG_ERR,"pfInit: BIOCPROMISC: %m"); 143 return (-1); 144 } 145 146 /* Set filter program. */ 147 insns[1].k = protocol; 148 insns[3].k = protocol; 149 150 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 151 syslog(LOG_ERR,"pfInit: BIOCSETF: %m"); 152 return (-1); 153 } 154 155 /* XXX set the same write filter (for protocol only) */ 156 if (ioctl(fd, BIOCSETWF, (caddr_t) & filter) < 0) { 157 syslog(LOG_ERR,"pfInit: BIOCSETWF: %m"); 158 return (-1); 159 } 160 161 /* Lock the interface to prevent further changes */ 162 if (ioctl(fd, BIOCLOCK) < 0) { 163 syslog(LOG_ERR,"pfInit: BIOCLOCK: %m"); 164 return (-1); 165 } 166 167 return (fd); 168 } 169 170 /* 171 * Add a Multicast address to the interface 172 */ 173 int 174 pfAddMulti(int s, char *interface, char *addr) 175 { 176 struct ifreq ifr; 177 int fd; 178 179 strncpy(ifr.ifr_name, interface, sizeof(ifr.ifr_name) - 1); 180 ifr.ifr_name[sizeof(ifr.ifr_name) - 1] = 0; 181 182 ifr.ifr_addr.sa_family = AF_UNSPEC; 183 bcopy(addr, ifr.ifr_addr.sa_data, 6); 184 185 /* 186 * open a socket, temporarily, to use for SIOC* ioctls 187 */ 188 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 189 syslog(LOG_ERR, "pfAddMulti: socket: %m"); 190 return (-1); 191 } 192 if (ioctl(fd, SIOCADDMULTI, (caddr_t)&ifr) < 0) { 193 syslog(LOG_ERR, "pfAddMulti: SIOCADDMULTI: %m"); 194 close(fd); 195 return (-1); 196 } 197 close(fd); 198 199 return (0); 200 } 201 202 /* 203 * Delete a Multicast address from the interface 204 */ 205 int 206 pfDelMulti(int s, char *interface, char *addr) 207 { 208 struct ifreq ifr; 209 int fd; 210 211 strncpy(ifr.ifr_name, interface, sizeof (ifr.ifr_name) - 1); 212 ifr.ifr_name[sizeof(ifr.ifr_name)-1] = 0; 213 214 ifr.ifr_addr.sa_family = AF_UNSPEC; 215 bcopy(addr, ifr.ifr_addr.sa_data, 6); 216 217 /* 218 * open a socket, temporarily, to use for SIOC* ioctls 219 * 220 */ 221 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 222 syslog(LOG_ERR, "pfDelMulti: socket: %m"); 223 return (-1); 224 } 225 if (ioctl(fd, SIOCDELMULTI, (caddr_t)&ifr) < 0) { 226 syslog(LOG_ERR, "pfAddMulti: SIOCDELMULTI: %m"); 227 close(fd); 228 return (-1); 229 } 230 close(fd); 231 232 return (0); 233 } 234 235 /* 236 * read a packet 237 */ 238 int 239 pfRead(int fd, u_char *buf, int len) 240 { 241 return (read(fd, buf, len)); 242 } 243 244 /* 245 * write a packet 246 */ 247 int 248 pfWrite(int fd, u_char *buf, int len, int trans) 249 { 250 struct iovec iov[2]; 251 252 /* XXX */ 253 switch (trans) { 254 case TRANS_8023: 255 iov[0].iov_base = buf; 256 iov[0].iov_len = 22; 257 iov[1].iov_base = buf + 22; 258 iov[1].iov_len = len - 22; 259 break; 260 default: 261 iov[0].iov_base = buf; 262 iov[0].iov_len = 14; 263 iov[1].iov_base = buf + 14; 264 iov[1].iov_len = len - 14; 265 break; 266 } 267 268 if (writev(fd, iov, 2) == len) 269 return (len); 270 271 return (-1); 272 } 273 274