1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * dhcpcd - DHCP client daemon 4 * Copyright (c) 2006-2020 Roy Marples <roy@marples.name> 5 * All rights reserved 6 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/socket.h> 30 #include <sys/stat.h> 31 #include <sys/uio.h> 32 #include <sys/un.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <time.h> 40 #include <unistd.h> 41 42 #include "config.h" 43 #include "common.h" 44 #include "dhcpcd.h" 45 #include "control.h" 46 #include "eloop.h" 47 #include "if.h" 48 #include "logerr.h" 49 50 #ifndef SUN_LEN 51 #define SUN_LEN(su) \ 52 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 53 #endif 54 55 static void 56 control_queue_free(struct fd_list *fd) 57 { 58 struct fd_data *fdp; 59 60 while ((fdp = TAILQ_FIRST(&fd->queue))) { 61 TAILQ_REMOVE(&fd->queue, fdp, next); 62 if (fdp->data_size != 0) 63 free(fdp->data); 64 free(fdp); 65 } 66 fd->queue_len = 0; 67 68 #ifdef CTL_FREE_LIST 69 while ((fdp = TAILQ_FIRST(&fd->free_queue))) { 70 TAILQ_REMOVE(&fd->free_queue, fdp, next); 71 if (fdp->data_size != 0) 72 free(fdp->data); 73 free(fdp); 74 } 75 #endif 76 } 77 78 static void 79 control_delete(struct fd_list *fd) 80 { 81 82 TAILQ_REMOVE(&fd->ctx->control_fds, fd, next); 83 eloop_event_delete(fd->ctx->eloop, fd->fd); 84 close(fd->fd); 85 control_queue_free(fd); 86 free(fd); 87 } 88 89 static void 90 control_handle_data(void *arg) 91 { 92 struct fd_list *fd = arg; 93 char buffer[1024], *e, *p, *argvp[255], **ap, *a; 94 ssize_t bytes; 95 size_t len; 96 int argc; 97 98 bytes = read(fd->fd, buffer, sizeof(buffer) - 1); 99 if (bytes == -1 || bytes == 0) { 100 /* Control was closed or there was an error. 101 * Remove it from our list. */ 102 control_delete(fd); 103 return; 104 } 105 buffer[bytes] = '\0'; 106 p = buffer; 107 e = buffer + bytes; 108 109 /* Each command is \n terminated 110 * Each argument is NULL separated */ 111 while (p < e) { 112 argc = 0; 113 ap = argvp; 114 while (p < e) { 115 argc++; 116 if ((size_t)argc >= sizeof(argvp) / sizeof(argvp[0])) { 117 errno = ENOBUFS; 118 return; 119 } 120 a = *ap++ = p; 121 len = strlen(p); 122 p += len + 1; 123 if (len && a[len - 1] == '\n') { 124 a[len - 1] = '\0'; 125 break; 126 } 127 } 128 *ap = NULL; 129 if (dhcpcd_handleargs(fd->ctx, fd, argc, argvp) == -1) { 130 logerr(__func__); 131 if (errno != EINTR && errno != EAGAIN) { 132 control_delete(fd); 133 return; 134 } 135 } 136 } 137 } 138 139 static void 140 control_handle1(struct dhcpcd_ctx *ctx, int lfd, unsigned int fd_flags) 141 { 142 struct sockaddr_un run; 143 socklen_t len; 144 struct fd_list *l; 145 int fd, flags; 146 147 len = sizeof(run); 148 if ((fd = accept(lfd, (struct sockaddr *)&run, &len)) == -1) 149 goto error; 150 if ((flags = fcntl(fd, F_GETFD, 0)) == -1 || 151 fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) 152 goto error; 153 if ((flags = fcntl(fd, F_GETFL, 0)) == -1 || 154 fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) 155 goto error; 156 157 l = malloc(sizeof(*l)); 158 if (l == NULL) 159 goto error; 160 161 l->ctx = ctx; 162 l->fd = fd; 163 l->flags = fd_flags; 164 TAILQ_INIT(&l->queue); 165 l->queue_len = 0; 166 #ifdef CTL_FREE_LIST 167 TAILQ_INIT(&l->free_queue); 168 #endif 169 TAILQ_INSERT_TAIL(&ctx->control_fds, l, next); 170 eloop_event_add(ctx->eloop, l->fd, control_handle_data, l); 171 return; 172 173 error: 174 logerr(__func__); 175 if (fd != -1) 176 close(fd); 177 } 178 179 static void 180 control_handle(void *arg) 181 { 182 struct dhcpcd_ctx *ctx = arg; 183 184 control_handle1(ctx, ctx->control_fd, 0); 185 } 186 187 static void 188 control_handle_unpriv(void *arg) 189 { 190 struct dhcpcd_ctx *ctx = arg; 191 192 control_handle1(ctx, ctx->control_unpriv_fd, FD_UNPRIV); 193 } 194 195 static int 196 make_sock(struct sockaddr_un *sa, const char *ifname, bool unpriv) 197 { 198 int fd; 199 200 #define SOCK_FLAGS SOCK_CLOEXEC | SOCK_NONBLOCK 201 if ((fd = xsocket(AF_UNIX, SOCK_STREAM | SOCK_FLAGS, 0)) == -1) 202 return -1; 203 #undef SOCK_FLAGS 204 memset(sa, 0, sizeof(*sa)); 205 sa->sun_family = AF_UNIX; 206 if (unpriv) 207 strlcpy(sa->sun_path, UNPRIVSOCKET, sizeof(sa->sun_path)); 208 else { 209 snprintf(sa->sun_path, sizeof(sa->sun_path), CONTROLSOCKET, 210 ifname ? ifname : "", ifname ? "." : ""); 211 } 212 return fd; 213 } 214 215 #define S_PRIV (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP) 216 #define S_UNPRIV (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH) 217 218 static int 219 control_start1(struct dhcpcd_ctx *ctx, const char *ifname, mode_t fmode) 220 { 221 struct sockaddr_un sa; 222 int fd; 223 socklen_t len; 224 225 if ((fd = make_sock(&sa, ifname, (fmode & S_UNPRIV) == S_UNPRIV)) == -1) 226 return -1; 227 len = (socklen_t)SUN_LEN(&sa); 228 unlink(sa.sun_path); 229 if (bind(fd, (struct sockaddr *)&sa, len) == -1 || 230 chmod(sa.sun_path, fmode) == -1 || 231 (ctx->control_group && 232 chown(sa.sun_path, geteuid(), ctx->control_group) == -1) || 233 listen(fd, sizeof(ctx->control_fds)) == -1) 234 { 235 close(fd); 236 unlink(sa.sun_path); 237 return -1; 238 } 239 240 if ((fmode & S_UNPRIV) != S_UNPRIV) 241 strlcpy(ctx->control_sock, sa.sun_path, 242 sizeof(ctx->control_sock)); 243 return fd; 244 } 245 246 int 247 control_start(struct dhcpcd_ctx *ctx, const char *ifname) 248 { 249 int fd; 250 251 if ((fd = control_start1(ctx, ifname, S_PRIV)) == -1) 252 return -1; 253 254 ctx->control_fd = fd; 255 eloop_event_add(ctx->eloop, fd, control_handle, ctx); 256 257 if (ifname == NULL && (fd = control_start1(ctx, NULL, S_UNPRIV)) != -1){ 258 /* We must be in master mode, so create an unprivileged socket 259 * to allow normal users to learn the status of dhcpcd. */ 260 ctx->control_unpriv_fd = fd; 261 eloop_event_add(ctx->eloop, fd, control_handle_unpriv, ctx); 262 } 263 return ctx->control_fd; 264 } 265 266 static int 267 control_unlink(struct dhcpcd_ctx *ctx, const char *file) 268 { 269 int retval = 0; 270 271 errno = 0; 272 #ifdef PRIVSEP 273 if (ctx->options & DHCPCD_PRIVSEP) 274 retval = (int)ps_root_unlink(ctx, file); 275 else 276 #else 277 UNUSED(ctx); 278 #endif 279 retval = unlink(file); 280 281 return retval == -1 && errno != ENOENT ? -1 : 0; 282 } 283 284 int 285 control_stop(struct dhcpcd_ctx *ctx) 286 { 287 int retval = 0; 288 struct fd_list *l; 289 290 if (ctx->options & DHCPCD_FORKED) 291 return 0; 292 293 if (ctx->control_fd != -1) { 294 eloop_event_delete(ctx->eloop, ctx->control_fd); 295 close(ctx->control_fd); 296 ctx->control_fd = -1; 297 if (control_unlink(ctx, ctx->control_sock) == -1) 298 retval = -1; 299 } 300 301 if (ctx->control_unpriv_fd != -1) { 302 eloop_event_delete(ctx->eloop, ctx->control_unpriv_fd); 303 close(ctx->control_unpriv_fd); 304 ctx->control_unpriv_fd = -1; 305 if (control_unlink(ctx, UNPRIVSOCKET) == -1) 306 retval = -1; 307 } 308 309 while ((l = TAILQ_FIRST(&ctx->control_fds))) { 310 TAILQ_REMOVE(&ctx->control_fds, l, next); 311 eloop_event_delete(ctx->eloop, l->fd); 312 close(l->fd); 313 control_queue_free(l); 314 free(l); 315 } 316 317 return retval; 318 } 319 320 int 321 control_open(const char *ifname, bool unpriv) 322 { 323 struct sockaddr_un sa; 324 int fd; 325 326 if ((fd = make_sock(&sa, ifname, unpriv)) != -1) { 327 socklen_t len; 328 329 len = (socklen_t)SUN_LEN(&sa); 330 if (connect(fd, (struct sockaddr *)&sa, len) == -1) { 331 close(fd); 332 fd = -1; 333 } 334 } 335 return fd; 336 } 337 338 ssize_t 339 control_send(struct dhcpcd_ctx *ctx, int argc, char * const *argv) 340 { 341 char buffer[1024]; 342 int i; 343 size_t len, l; 344 345 if (argc > 255) { 346 errno = ENOBUFS; 347 return -1; 348 } 349 len = 0; 350 for (i = 0; i < argc; i++) { 351 l = strlen(argv[i]) + 1; 352 if (len + l > sizeof(buffer)) { 353 errno = ENOBUFS; 354 return -1; 355 } 356 memcpy(buffer + len, argv[i], l); 357 len += l; 358 } 359 return write(ctx->control_fd, buffer, len); 360 } 361 362 static void 363 control_writeone(void *arg) 364 { 365 struct fd_list *fd; 366 struct iovec iov[2]; 367 struct fd_data *data; 368 369 fd = arg; 370 data = TAILQ_FIRST(&fd->queue); 371 iov[0].iov_base = &data->data_len; 372 iov[0].iov_len = sizeof(size_t); 373 iov[1].iov_base = data->data; 374 iov[1].iov_len = data->data_len; 375 if (writev(fd->fd, iov, 2) == -1) { 376 logerr(__func__); 377 if (errno != EINTR && errno != EAGAIN) 378 control_delete(fd); 379 return; 380 } 381 382 TAILQ_REMOVE(&fd->queue, data, next); 383 fd->queue_len--; 384 #ifdef CTL_FREE_LIST 385 TAILQ_INSERT_TAIL(&fd->free_queue, data, next); 386 #else 387 if (data->data_size != 0) 388 free(data->data); 389 free(data); 390 #endif 391 392 if (TAILQ_FIRST(&fd->queue) == NULL) 393 eloop_event_remove_writecb(fd->ctx->eloop, fd->fd); 394 } 395 396 int 397 control_queue(struct fd_list *fd, void *data, size_t data_len, bool fit) 398 { 399 struct fd_data *d; 400 401 if (data_len == 0) 402 return 0; 403 404 #ifdef CTL_FREE_LIST 405 struct fd_data *df; 406 407 d = NULL; 408 TAILQ_FOREACH(df, &fd->free_queue, next) { 409 if (!fit) { 410 if (df->data_size == 0) { 411 d = df; 412 break; 413 } 414 continue; 415 } 416 if (d == NULL || d->data_size < df->data_size) { 417 d = df; 418 if (d->data_size <= data_len) 419 break; 420 } 421 } 422 if (d != NULL) 423 TAILQ_REMOVE(&fd->free_queue, d, next); 424 else 425 #endif 426 { 427 if (fd->queue_len == CONTROL_QUEUE_MAX) { 428 errno = ENOBUFS; 429 return -1; 430 } 431 fd->queue_len++; 432 d = calloc(1, sizeof(*d)); 433 if (d == NULL) 434 return -1; 435 } 436 437 if (!fit) { 438 #ifdef CTL_FREE_LIST 439 if (d->data_size != 0) { 440 free(d->data); 441 d->data_size = 0; 442 } 443 #endif 444 d->data = data; 445 d->data_len = data_len; 446 goto queue; 447 } 448 449 if (d->data_size == 0) 450 d->data = NULL; 451 if (d->data_size < data_len) { 452 void *nbuf = realloc(d->data, data_len); 453 if (nbuf == NULL) { 454 free(d->data); 455 free(d); 456 return -1; 457 } 458 d->data = nbuf; 459 d->data_size = data_len; 460 } 461 memcpy(d->data, data, data_len); 462 d->data_len = data_len; 463 464 queue: 465 TAILQ_INSERT_TAIL(&fd->queue, d, next); 466 eloop_event_add_w(fd->ctx->eloop, fd->fd, control_writeone, fd); 467 return 0; 468 } 469