1 /* $OpenBSD: control.c,v 1.17 2021/02/24 18:34:14 florian Exp $ */ 2 3 /* 4 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 #include <sys/types.h> 19 #include <sys/queue.h> 20 #include <sys/stat.h> 21 #include <sys/socket.h> 22 #include <sys/time.h> 23 #include <sys/un.h> 24 25 #include <net/route.h> 26 27 #include <errno.h> 28 #include <event.h> 29 #include <imsg.h> 30 #include <stdlib.h> 31 #include <string.h> 32 #include <unistd.h> 33 34 #include "log.h" 35 #include "unwind.h" 36 #include "control.h" 37 #include "frontend.h" 38 #include "resolver.h" 39 40 #define CONTROL_BACKLOG 5 41 42 struct { 43 struct event ev; 44 struct event evt; 45 int fd; 46 } control_state = {.fd = -1}; 47 48 struct ctl_conn { 49 TAILQ_ENTRY(ctl_conn) entry; 50 struct imsgev iev; 51 }; 52 53 TAILQ_HEAD(ctl_conns, ctl_conn) ctl_conns = TAILQ_HEAD_INITIALIZER(ctl_conns); 54 55 struct ctl_conn *control_connbyfd(int); 56 struct ctl_conn *control_connbypid(pid_t); 57 void control_close(int); 58 59 int 60 control_init(char *path) 61 { 62 struct sockaddr_un sun; 63 int fd; 64 mode_t old_umask; 65 66 if ((fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 67 0)) == -1) { 68 log_warn("%s: socket", __func__); 69 return (-1); 70 } 71 72 memset(&sun, 0, sizeof(sun)); 73 sun.sun_family = AF_UNIX; 74 strlcpy(sun.sun_path, path, sizeof(sun.sun_path)); 75 76 if (unlink(path) == -1) 77 if (errno != ENOENT) { 78 log_warn("%s: unlink %s", __func__, path); 79 close(fd); 80 return (-1); 81 } 82 83 old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH); 84 if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) { 85 log_warn("%s: bind: %s", __func__, path); 86 close(fd); 87 umask(old_umask); 88 return (-1); 89 } 90 umask(old_umask); 91 92 if (chmod(path, 93 S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH) == -1) { 94 log_warn("%s: chmod", __func__); 95 close(fd); 96 (void)unlink(path); 97 return (-1); 98 } 99 100 return (fd); 101 } 102 103 int 104 control_listen(int fd) 105 { 106 if (control_state.fd != -1) 107 fatalx("%s: received unexpected controlsock", __func__); 108 109 control_state.fd = fd; 110 if (listen(control_state.fd, CONTROL_BACKLOG) == -1) { 111 log_warn("%s: listen", __func__); 112 return (-1); 113 } 114 115 event_set(&control_state.ev, control_state.fd, EV_READ, 116 control_accept, NULL); 117 event_add(&control_state.ev, NULL); 118 evtimer_set(&control_state.evt, control_accept, NULL); 119 120 return (0); 121 } 122 123 void 124 control_accept(int listenfd, short event, void *bula) 125 { 126 int connfd; 127 socklen_t len; 128 struct sockaddr_un sun; 129 struct ctl_conn *c; 130 131 event_add(&control_state.ev, NULL); 132 if ((event & EV_TIMEOUT)) 133 return; 134 135 len = sizeof(sun); 136 if ((connfd = accept4(listenfd, (struct sockaddr *)&sun, &len, 137 SOCK_CLOEXEC | SOCK_NONBLOCK)) == -1) { 138 /* 139 * Pause accept if we are out of file descriptors, or 140 * libevent will haunt us here too. 141 */ 142 if (errno == ENFILE || errno == EMFILE) { 143 struct timeval evtpause = { 1, 0 }; 144 145 event_del(&control_state.ev); 146 evtimer_add(&control_state.evt, &evtpause); 147 } else if (errno != EWOULDBLOCK && errno != EINTR && 148 errno != ECONNABORTED) 149 log_warn("%s: accept4", __func__); 150 return; 151 } 152 153 if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) { 154 log_warn("%s: calloc", __func__); 155 close(connfd); 156 return; 157 } 158 159 imsg_init(&c->iev.ibuf, connfd); 160 c->iev.handler = control_dispatch_imsg; 161 c->iev.events = EV_READ; 162 event_set(&c->iev.ev, c->iev.ibuf.fd, c->iev.events, c->iev.handler, 163 &c->iev); 164 event_add(&c->iev.ev, NULL); 165 166 TAILQ_INSERT_TAIL(&ctl_conns, c, entry); 167 } 168 169 struct ctl_conn * 170 control_connbyfd(int fd) 171 { 172 struct ctl_conn *c; 173 174 TAILQ_FOREACH(c, &ctl_conns, entry) { 175 if (c->iev.ibuf.fd == fd) 176 break; 177 } 178 179 return (c); 180 } 181 182 struct ctl_conn * 183 control_connbypid(pid_t pid) 184 { 185 struct ctl_conn *c; 186 187 TAILQ_FOREACH(c, &ctl_conns, entry) { 188 if (c->iev.ibuf.pid == pid) 189 break; 190 } 191 192 return (c); 193 } 194 195 void 196 control_close(int fd) 197 { 198 struct ctl_conn *c; 199 200 if ((c = control_connbyfd(fd)) == NULL) { 201 log_warnx("%s: fd %d: not found", __func__, fd); 202 return; 203 } 204 205 msgbuf_clear(&c->iev.ibuf.w); 206 TAILQ_REMOVE(&ctl_conns, c, entry); 207 208 event_del(&c->iev.ev); 209 close(c->iev.ibuf.fd); 210 211 /* Some file descriptors are available again. */ 212 if (evtimer_pending(&control_state.evt, NULL)) { 213 evtimer_del(&control_state.evt); 214 event_add(&control_state.ev, NULL); 215 } 216 217 free(c); 218 } 219 220 void 221 control_dispatch_imsg(int fd, short event, void *bula) 222 { 223 struct ctl_conn *c; 224 struct imsg imsg; 225 ssize_t n; 226 int verbose; 227 uid_t euid; 228 gid_t egid; 229 230 if ((c = control_connbyfd(fd)) == NULL) { 231 log_warnx("%s: fd %d: not found", __func__, fd); 232 return; 233 } 234 235 if (event & EV_READ) { 236 if (((n = imsg_read(&c->iev.ibuf)) == -1 && errno != EAGAIN) || 237 n == 0) { 238 control_close(fd); 239 return; 240 } 241 } 242 if (event & EV_WRITE) { 243 if (msgbuf_write(&c->iev.ibuf.w) <= 0 && errno != EAGAIN) { 244 control_close(fd); 245 return; 246 } 247 } 248 249 if (getpeereid(fd, &euid, &egid) == -1) { 250 control_close(fd); 251 return; 252 } 253 254 for (;;) { 255 if ((n = imsg_get(&c->iev.ibuf, &imsg)) == -1) { 256 control_close(fd); 257 return; 258 } 259 if (n == 0) 260 break; 261 262 switch (imsg.hdr.type) { 263 case IMSG_CTL_LOG_VERBOSE: 264 case IMSG_CTL_RELOAD: 265 if (euid != 0) { 266 imsg_free(&imsg); 267 control_close(fd); 268 return; 269 } 270 break; 271 default: 272 break; 273 } 274 275 c->iev.ibuf.pid = imsg.hdr.pid; 276 switch (imsg.hdr.type) { 277 case IMSG_CTL_RELOAD: 278 frontend_imsg_compose_main(imsg.hdr.type, imsg.hdr.pid, 279 NULL, 0); 280 break; 281 case IMSG_CTL_LOG_VERBOSE: 282 if (IMSG_DATA_SIZE(imsg) != sizeof(verbose)) 283 break; 284 285 /* Forward to all other processes. */ 286 frontend_imsg_compose_main(imsg.hdr.type, imsg.hdr.pid, 287 imsg.data, IMSG_DATA_SIZE(imsg)); 288 frontend_imsg_compose_resolver(imsg.hdr.type, 289 imsg.hdr.pid, imsg.data, IMSG_DATA_SIZE(imsg)); 290 291 memcpy(&verbose, imsg.data, sizeof(verbose)); 292 log_setverbose(verbose); 293 break; 294 case IMSG_CTL_STATUS: 295 case IMSG_CTL_AUTOCONF: 296 case IMSG_CTL_MEM: 297 if (IMSG_DATA_SIZE(imsg) != 0) 298 break; 299 frontend_imsg_compose_resolver(imsg.hdr.type, 300 imsg.hdr.pid, NULL, 0); 301 break; 302 default: 303 log_debug("%s: error handling imsg %d", __func__, 304 imsg.hdr.type); 305 break; 306 } 307 imsg_free(&imsg); 308 } 309 310 imsg_event_add(&c->iev); 311 } 312 313 int 314 control_imsg_relay(struct imsg *imsg) 315 { 316 struct ctl_conn *c; 317 318 if ((c = control_connbypid(imsg->hdr.pid)) == NULL) 319 return (0); 320 321 return (imsg_compose_event(&c->iev, imsg->hdr.type, 0, imsg->hdr.pid, 322 -1, imsg->data, IMSG_DATA_SIZE(*imsg))); 323 } 324