ip/iptuntap.c

   1 /*
   2  * iptunnel.c          "ip tuntap"
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     David Woodhouse <David.Woodhouse@intel.com>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <sys/types.h>
  18 #include <sys/socket.h>
  19 #include <arpa/inet.h>
  20 #include <sys/ioctl.h>
  21 #include <linux/if.h>
  22 #include <linux/if_tun.h>
  23 #include <linux/if_arp.h>
  24 #include <pwd.h>
  25 #include <grp.h>
  26 #include <fcntl.h>
  27 #include <dirent.h>
  28 #include <errno.h>
  29 #include <glob.h>
  30
  31 #include "rt_names.h"
  32 #include "utils.h"
  33 #include "ip_common.h"
  34
  35 static const char drv_name[] = "tun";
  36
  37 #define TUNDEV "/dev/net/tun"
  38
  39 static void usage(void) __attribute__((noreturn));
  40
  41 static void usage(void)
  42 {
  43         fprintf(stderr, "Usage: ip tuntap { add | del | show | list | lst | help } [ dev PHYS_DEV ]\n");
  44         fprintf(stderr, "          [ mode { tun | tap } ] [ user USER ] [ group GROUP ]\n");
  45         fprintf(stderr, "          [ one_queue ] [ pi ] [ vnet_hdr ] [ multi_queue ] [ name NAME ]\n");
  46         fprintf(stderr, "\n");
  47         fprintf(stderr, "Where: USER  := { STRING | NUMBER }\n");
  48         fprintf(stderr, "       GROUP := { STRING | NUMBER }\n");
  49         exit(-1);
  50 }
  51
  52 static int tap_add_ioctl(struct ifreq *ifr, uid_t uid, gid_t gid)
  53 {
  54         int fd;
  55         int ret = -1;
  56
  57 #ifdef IFF_TUN_EXCL
  58         ifr->ifr_flags |= IFF_TUN_EXCL;
  59 #endif
  60
  61         fd = open(TUNDEV, O_RDWR);
  62         if (fd < 0) {
  63                 perror("open");
  64                 return -1;
  65         }
  66         if (ioctl(fd, TUNSETIFF, ifr)) {
  67                 perror("ioctl(TUNSETIFF)");
  68                 goto out;
  69         }
  70         if (uid != -1 && ioctl(fd, TUNSETOWNER, uid)) {
  71                 perror("ioctl(TUNSETOWNER)");
  72                 goto out;
  73         }
  74         if (gid != -1 && ioctl(fd, TUNSETGROUP, gid)) {
  75                 perror("ioctl(TUNSETGROUP)");
  76                 goto out;
  77         }
  78         if (ioctl(fd, TUNSETPERSIST, 1)) {
  79                 perror("ioctl(TUNSETPERSIST)");
  80                 goto out;
  81         }
  82         ret = 0;
  83  out:
  84         close(fd);
  85         return ret;
  86 }
  87
  88 static int tap_del_ioctl(struct ifreq *ifr)
  89 {
  90         int fd = open(TUNDEV, O_RDWR);
  91         int ret = -1;
  92
  93         if (fd < 0) {
  94                 perror("open");
  95                 return -1;
  96         }
  97         if (ioctl(fd, TUNSETIFF, ifr)) {
  98                 perror("ioctl(TUNSETIFF)");
  99                 goto out;
 100         }
 101         if (ioctl(fd, TUNSETPERSIST, 0)) {
 102                 perror("ioctl(TUNSETPERSIST)");
 103                 goto out;
 104         }
 105         ret = 0;
 106  out:
 107         close(fd);
 108         return ret;
 109
 110 }
 111 static int parse_args(int argc, char **argv,
 112                       struct ifreq *ifr, uid_t *uid, gid_t *gid)
 113 {
 114         int count = 0;
 115
 116         memset(ifr, 0, sizeof(*ifr));
 117
 118         ifr->ifr_flags |= IFF_NO_PI;
 119
 120         while (argc > 0) {
 121                 if (matches(*argv, "mode") == 0) {
 122                         NEXT_ARG();
 123                         if (matches(*argv, "tun") == 0) {
 124                                 if (ifr->ifr_flags & IFF_TAP) {
 125                                         fprintf(stderr, "You managed to ask for more than one tunnel mode.\n");
 126                                         exit(-1);
 127                                 }
 128                                 ifr->ifr_flags |= IFF_TUN;
 129                         } else if (matches(*argv, "tap") == 0) {
 130                                 if (ifr->ifr_flags & IFF_TUN) {
 131                                         fprintf(stderr, "You managed to ask for more than one tunnel mode.\n");
 132                                         exit(-1);
 133                                 }
 134                                 ifr->ifr_flags |= IFF_TAP;
 135                         } else {
 136                                 fprintf(stderr, "Unknown tunnel mode \"%s\"\n", *argv);
 137                                 exit(-1);
 138                         }
 139                 } else if (uid && matches(*argv, "user") == 0) {
 140                         char *end;
 141                         unsigned long user;
 142
 143                         NEXT_ARG();
 144                         if (**argv && ((user = strtol(*argv, &end, 10)), !*end))
 145                                 *uid = user;
 146                         else {
 147                                 struct passwd *pw = getpwnam(*argv);
 148
 149                                 if (!pw) {
 150                                         fprintf(stderr, "invalid user \"%s\"\n", *argv);
 151                                         exit(-1);
 152                                 }
 153                                 *uid = pw->pw_uid;
 154                         }
 155                 } else if (gid && matches(*argv, "group") == 0) {
 156                         char *end;
 157                         unsigned long group;
 158
 159                         NEXT_ARG();
 160
 161                         if (**argv && ((group = strtol(*argv, &end, 10)), !*end))
 162                                 *gid = group;
 163                         else {
 164                                 struct group *gr = getgrnam(*argv);
 165
 166                                 if (!gr) {
 167                                         fprintf(stderr, "invalid group \"%s\"\n", *argv);
 168                                         exit(-1);
 169                                 }
 170                                 *gid = gr->gr_gid;
 171                         }
 172                 } else if (matches(*argv, "pi") == 0) {
 173                         ifr->ifr_flags &= ~IFF_NO_PI;
 174                 } else if (matches(*argv, "one_queue") == 0) {
 175                         ifr->ifr_flags |= IFF_ONE_QUEUE;
 176                 } else if (matches(*argv, "vnet_hdr") == 0) {
 177                         ifr->ifr_flags |= IFF_VNET_HDR;
 178                 } else if (matches(*argv, "multi_queue") == 0) {
 179                         ifr->ifr_flags |= IFF_MULTI_QUEUE;
 180                 } else if (matches(*argv, "dev") == 0) {
 181                         NEXT_ARG();
 182                         if (get_ifname(ifr->ifr_name, *argv))
 183                                 invarg("\"dev\" not a valid ifname", *argv);
 184                 } else {
 185                         if (matches(*argv, "name") == 0) {
 186                                 NEXT_ARG();
 187                         } else if (matches(*argv, "help") == 0)
 188                                 usage();
 189                         if (ifr->ifr_name[0])
 190                                 duparg2("name", *argv);
 191                         if (get_ifname(ifr->ifr_name, *argv))
 192                                 invarg("\"name\" not a valid ifname", *argv);
 193                 }
 194                 count++;
 195                 argc--; argv++;
 196         }
 197
 198         if (!(ifr->ifr_flags & TUN_TYPE_MASK)) {
 199                 fprintf(stderr, "You failed to specify a tunnel mode\n");
 200                 return -1;
 201         }
 202
 203         return 0;
 204 }
 205
 206
 207 static int do_add(int argc, char **argv)
 208 {
 209         struct ifreq ifr;
 210         uid_t uid = -1;
 211         gid_t gid = -1;
 212
 213         if (parse_args(argc, argv, &ifr, &uid, &gid) < 0)
 214                 return -1;
 215
 216         return tap_add_ioctl(&ifr, uid, gid);
 217 }
 218
 219 static int do_del(int argc, char **argv)
 220 {
 221         struct ifreq ifr;
 222
 223         if (parse_args(argc, argv, &ifr, NULL, NULL) < 0)
 224                 return -1;
 225
 226         return tap_del_ioctl(&ifr);
 227 }
 228
 229 static void print_flags(long flags)
 230 {
 231         if (flags & IFF_TUN)
 232                 printf(" tun");
 233
 234         if (flags & IFF_TAP)
 235                 printf(" tap");
 236
 237         if (!(flags & IFF_NO_PI))
 238                 printf(" pi");
 239
 240         if (flags & IFF_ONE_QUEUE)
 241                 printf(" one_queue");
 242
 243         if (flags & IFF_VNET_HDR)
 244                 printf(" vnet_hdr");
 245
 246         flags &= ~(IFF_TUN|IFF_TAP|IFF_NO_PI|IFF_ONE_QUEUE|IFF_VNET_HDR);
 247         if (flags)
 248                 printf(" UNKNOWN_FLAGS:%lx", flags);
 249 }
 250
 251 static char *pid_name(pid_t pid)
 252 {
 253         char *comm;
 254         FILE *f;
 255         int err;
 256
 257         err = asprintf(&comm, "/proc/%d/comm", pid);
 258         if (err < 0)
 259                 return NULL;
 260
 261         f = fopen(comm, "r");
 262         free(comm);
 263         if (!f) {
 264                 perror("fopen");
 265                 return NULL;
 266         }
 267
 268         if (fscanf(f, "%ms\n", &comm) != 1) {
 269                 perror("fscanf");
 270                 comm = NULL;
 271         }
 272
 273
 274         if (fclose(f))
 275                 perror("fclose");
 276
 277         return comm;
 278 }
 279
 280 static void show_processes(const char *name)
 281 {
 282         glob_t globbuf = { };
 283         char **fd_path;
 284         int err;
 285
 286         err = glob("/proc/[0-9]*/fd/[0-9]*", GLOB_NOSORT,
 287                    NULL, &globbuf);
 288         if (err)
 289                 return;
 290
 291         fd_path = globbuf.gl_pathv;
 292         while (*fd_path) {
 293                 const char *dev_net_tun = "/dev/net/tun";
 294                 const size_t linkbuf_len = strlen(dev_net_tun) + 2;
 295                 char linkbuf[linkbuf_len], *fdinfo;
 296                 int pid, fd;
 297                 FILE *f;
 298
 299                 if (sscanf(*fd_path, "/proc/%d/fd/%d", &pid, &fd) != 2)
 300                         goto next;
 301
 302                 if (pid == getpid())
 303                         goto next;
 304
 305                 err = readlink(*fd_path, linkbuf, linkbuf_len - 1);
 306                 if (err < 0) {
 307                         perror("readlink");
 308                         goto next;
 309                 }
 310                 linkbuf[err] = '\0';
 311                 if (strcmp(dev_net_tun, linkbuf))
 312                         goto next;
 313
 314                 if (asprintf(&fdinfo, "/proc/%d/fdinfo/%d", pid, fd) < 0)
 315                         goto next;
 316
 317                 f = fopen(fdinfo, "r");
 318                 free(fdinfo);
 319                 if (!f) {
 320                         perror("fopen");
 321                         goto next;
 322                 }
 323
 324                 while (!feof(f)) {
 325                         char *key = NULL, *value = NULL;
 326
 327                         err = fscanf(f, "%m[^:]: %ms\n", &key, &value);
 328                         if (err == EOF) {
 329                                 if (ferror(f))
 330                                         perror("fscanf");
 331                                 break;
 332                         } else if (err == 2 &&
 333                                    !strcmp("iff", key) &&
 334                                    !strcmp(name, value)) {
 335                                 char *pname = pid_name(pid);
 336
 337                                 printf(" %s(%d)", pname ? : "<NULL>", pid);
 338                                 free(pname);
 339                         }
 340
 341                         free(key);
 342                         free(value);
 343                 }
 344                 if (fclose(f))
 345                         perror("fclose");
 346
 347 next:
 348                 ++fd_path;
 349         }
 350
 351         globfree(&globbuf);
 352 }
 353
 354 static int tuntap_filter_req(struct nlmsghdr *nlh, int reqlen)
 355 {
 356         struct rtattr *linkinfo;
 357         int err;
 358
 359         linkinfo = addattr_nest(nlh, reqlen, IFLA_LINKINFO);
 360
 361         err = addattr_l(nlh, reqlen, IFLA_INFO_KIND,
 362                         drv_name, sizeof(drv_name) - 1);
 363         if (err)
 364                 return err;
 365
 366         addattr_nest_end(nlh, linkinfo);
 367
 368         return 0;
 369 }
 370
 371 static int print_tuntap(const struct sockaddr_nl *who,
 372                         struct nlmsghdr *n, void *arg)
 373 {
 374         struct ifinfomsg *ifi = NLMSG_DATA(n);
 375         struct rtattr *tb[IFLA_MAX+1];
 376         struct rtattr *linkinfo[IFLA_INFO_MAX+1];
 377         const char *name, *kind;
 378         long flags, owner = -1, group = -1;
 379
 380         if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
 381                 return 0;
 382
 383         if (n->nlmsg_len < NLMSG_LENGTH(sizeof(*ifi)))
 384                 return -1;
 385
 386         switch (ifi->ifi_type) {
 387         case ARPHRD_NONE:
 388         case ARPHRD_ETHER:
 389                 break;
 390         default:
 391                 return 0;
 392         }
 393
 394         parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));
 395
 396         if (!tb[IFLA_IFNAME])
 397                 return 0;
 398
 399         if (!tb[IFLA_LINKINFO])
 400                 return 0;
 401
 402         parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
 403
 404         if (!linkinfo[IFLA_INFO_KIND])
 405                 return 0;
 406
 407         kind = rta_getattr_str(linkinfo[IFLA_INFO_KIND]);
 408         if (strcmp(kind, drv_name))
 409                 return 0;
 410
 411         name = rta_getattr_str(tb[IFLA_IFNAME]);
 412
 413         if (read_prop(name, "tun_flags", &flags))
 414                 return 0;
 415         if (read_prop(name, "owner", &owner))
 416                 return 0;
 417         if (read_prop(name, "group", &group))
 418                 return 0;
 419
 420         printf("%s:", name);
 421         print_flags(flags);
 422         if (owner != -1)
 423                 printf(" user %ld", owner);
 424         if (group != -1)
 425                 printf(" group %ld", group);
 426         fputc('\n', stdout);
 427         if (show_details) {
 428                 printf("\tAttached to processes:");
 429                 show_processes(name);
 430                 fputc('\n', stdout);
 431         }
 432
 433         return 0;
 434 }
 435
 436 static int do_show(int argc, char **argv)
 437 {
 438         if (rtnl_wilddump_req_filter_fn(&rth, AF_UNSPEC, RTM_GETLINK,
 439                                         tuntap_filter_req) < 0) {
 440                 perror("Cannot send dump request\n");
 441                 return -1;
 442         }
 443
 444         if (rtnl_dump_filter(&rth, print_tuntap, NULL) < 0) {
 445                 fprintf(stderr, "Dump terminated\n");
 446                 return -1;
 447         }
 448
 449         return 0;
 450 }
 451
 452 int do_iptuntap(int argc, char **argv)
 453 {
 454         if (argc > 0) {
 455                 if (matches(*argv, "add") == 0)
 456                         return do_add(argc-1, argv+1);
 457                 if (matches(*argv, "delete") == 0)
 458                         return do_del(argc-1, argv+1);
 459                 if (matches(*argv, "show") == 0 ||
 460                     matches(*argv, "lst") == 0 ||
 461                     matches(*argv, "list") == 0)
 462                         return do_show(argc-1, argv+1);
 463                 if (matches(*argv, "help") == 0)
 464                         usage();
 465         } else
 466                 return do_show(0, NULL);
 467
 468         fprintf(stderr, "Command \"%s\" is unknown, try \"ip tuntap help\".\n",
 469                 *argv);
 470         exit(-1);
 471 }
 472
 473 static void print_owner(FILE *f, uid_t uid)
 474 {
 475         struct passwd *pw = getpwuid(uid);
 476
 477         if (pw)
 478                 print_string(PRINT_ANY, "user", "user %s ", pw->pw_name);
 479         else
 480                 print_uint(PRINT_ANY, "user", "user %u ", uid);
 481 }
 482
 483 static void print_group(FILE *f, gid_t gid)
 484 {
 485         struct group *group = getgrgid(gid);
 486
 487         if (group)
 488                 print_string(PRINT_ANY, "group", "group %s ", group->gr_name);
 489         else
 490                 print_uint(PRINT_ANY, "group", "group %u ", gid);
 491 }
 492
 493 static void print_mq(FILE *f, struct rtattr *tb[])
 494 {
 495         if (!tb[IFLA_TUN_MULTI_QUEUE] ||
 496             !rta_getattr_u8(tb[IFLA_TUN_MULTI_QUEUE])) {
 497                 if (is_json_context())
 498                         print_bool(PRINT_JSON, "multi_queue", NULL, false);
 499                 return;
 500         }
 501
 502         print_bool(PRINT_ANY, "multi_queue", "multi_queue ", true);
 503
 504         if (tb[IFLA_TUN_NUM_QUEUES]) {
 505                 print_uint(PRINT_ANY, "numqueues", "numqueues %u ",
 506                            rta_getattr_u32(tb[IFLA_TUN_NUM_QUEUES]));
 507         }
 508
 509         if (tb[IFLA_TUN_NUM_DISABLED_QUEUES]) {
 510                 print_uint(PRINT_ANY, "numdisabled", "numdisabled %u ",
 511                            rta_getattr_u32(tb[IFLA_TUN_NUM_DISABLED_QUEUES]));
 512         }
 513 }
 514
 515 static void print_onoff(FILE *f, const char *flag, __u8 val)
 516 {
 517         if (is_json_context())
 518                 print_bool(PRINT_JSON, flag, NULL, !!val);
 519         else
 520                 fprintf(f, "%s %s ", flag, val ? "on" : "off");
 521 }
 522
 523 static void print_type(FILE *f, __u8 type)
 524 {
 525         SPRINT_BUF(buf);
 526         const char *str = buf;
 527
 528         if (type == IFF_TUN)
 529                 str = "tun";
 530         else if (type == IFF_TAP)
 531                 str = "tap";
 532         else
 533                 snprintf(buf, sizeof(buf), "UNKNOWN:%hhu", type);
 534
 535         print_string(PRINT_ANY, "type", "type %s ", str);
 536 }
 537
 538 static void tun_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 539 {
 540         if (!tb)
 541                 return;
 542
 543         if (tb[IFLA_TUN_TYPE])
 544                 print_type(f, rta_getattr_u8(tb[IFLA_TUN_TYPE]));
 545
 546         if (tb[IFLA_TUN_PI])
 547                 print_onoff(f, "pi", rta_getattr_u8(tb[IFLA_TUN_PI]));
 548
 549         if (tb[IFLA_TUN_VNET_HDR]) {
 550                 print_onoff(f, "vnet_hdr",
 551                             rta_getattr_u8(tb[IFLA_TUN_VNET_HDR]));
 552         }
 553
 554         print_mq(f, tb);
 555
 556         if (tb[IFLA_TUN_PERSIST])
 557                 print_onoff(f, "persist", rta_getattr_u8(tb[IFLA_TUN_PERSIST]));
 558
 559         if (tb[IFLA_TUN_OWNER])
 560                 print_owner(f, rta_getattr_u32(tb[IFLA_TUN_OWNER]));
 561
 562         if (tb[IFLA_TUN_GROUP])
 563                 print_group(f, rta_getattr_u32(tb[IFLA_TUN_GROUP]));
 564 }
 565
 566 struct link_util tun_link_util = {
 567         .id = "tun",
 568         .maxattr = IFLA_TUN_MAX,
 569         .print_opt = tun_print_opt,
 570 };