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         open_json_array(PRINT_JSON, "flags");
 232
 233         if (flags & IFF_TUN)
 234                 print_string(PRINT_ANY, NULL, " %s", "tun");
 235
 236         if (flags & IFF_TAP)
 237                 print_string(PRINT_ANY, NULL, " %s", "tap");
 238
 239         if (!(flags & IFF_NO_PI))
 240                 print_string(PRINT_ANY, NULL, " %s", "pi");
 241
 242         if (flags & IFF_ONE_QUEUE)
 243                 print_string(PRINT_ANY, NULL, " %s", "one_queue");
 244
 245         if (flags & IFF_VNET_HDR)
 246                 print_string(PRINT_ANY, NULL, " %s", "vnet_hdr");
 247
 248         if (flags & IFF_PERSIST)
 249                 print_string(PRINT_ANY, NULL, " %s", "persist");
 250
 251         if (!(flags & IFF_NOFILTER))
 252                 print_string(PRINT_ANY, NULL, " %s", "filter");
 253
 254         flags &= ~(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
 255                    IFF_VNET_HDR | IFF_PERSIST | IFF_NOFILTER);
 256         if (flags)
 257                 print_0xhex(PRINT_ANY, NULL, "%#x", flags);
 258
 259         close_json_array(PRINT_JSON, NULL);
 260 }
 261
 262 static char *pid_name(pid_t pid)
 263 {
 264         char *comm;
 265         FILE *f;
 266         int err;
 267
 268         err = asprintf(&comm, "/proc/%d/comm", pid);
 269         if (err < 0)
 270                 return NULL;
 271
 272         f = fopen(comm, "r");
 273         free(comm);
 274         if (!f) {
 275                 perror("fopen");
 276                 return NULL;
 277         }
 278
 279         if (fscanf(f, "%ms\n", &comm) != 1) {
 280                 perror("fscanf");
 281                 comm = NULL;
 282         }
 283
 284
 285         if (fclose(f))
 286                 perror("fclose");
 287
 288         return comm;
 289 }
 290
 291 static void show_processes(const char *name)
 292 {
 293         glob_t globbuf = { };
 294         char **fd_path;
 295         int err;
 296
 297         err = glob("/proc/[0-9]*/fd/[0-9]*", GLOB_NOSORT,
 298                    NULL, &globbuf);
 299         if (err)
 300                 return;
 301
 302         open_json_array(PRINT_JSON, "processes");
 303
 304         fd_path = globbuf.gl_pathv;
 305         while (*fd_path) {
 306                 const char *dev_net_tun = "/dev/net/tun";
 307                 const size_t linkbuf_len = strlen(dev_net_tun) + 2;
 308                 char linkbuf[linkbuf_len], *fdinfo;
 309                 int pid, fd;
 310                 FILE *f;
 311
 312                 if (sscanf(*fd_path, "/proc/%d/fd/%d", &pid, &fd) != 2)
 313                         goto next;
 314
 315                 if (pid == getpid())
 316                         goto next;
 317
 318                 err = readlink(*fd_path, linkbuf, linkbuf_len - 1);
 319                 if (err < 0) {
 320                         perror("readlink");
 321                         goto next;
 322                 }
 323                 linkbuf[err] = '\0';
 324                 if (strcmp(dev_net_tun, linkbuf))
 325                         goto next;
 326
 327                 if (asprintf(&fdinfo, "/proc/%d/fdinfo/%d", pid, fd) < 0)
 328                         goto next;
 329
 330                 f = fopen(fdinfo, "r");
 331                 free(fdinfo);
 332                 if (!f) {
 333                         perror("fopen");
 334                         goto next;
 335                 }
 336
 337                 while (!feof(f)) {
 338                         char *key = NULL, *value = NULL;
 339
 340                         err = fscanf(f, "%m[^:]: %ms\n", &key, &value);
 341                         if (err == EOF) {
 342                                 if (ferror(f))
 343                                         perror("fscanf");
 344                                 break;
 345                         } else if (err == 2 &&
 346                                    !strcmp("iff", key) &&
 347                                    !strcmp(name, value)) {
 348                                 char *pname = pid_name(pid);
 349
 350                                 print_string(PRINT_ANY, "name",
 351                                              "%s", pname ? : "<NULL>");
 352
 353                                 print_uint(PRINT_ANY, "pid",
 354                                            "(%d)", pid);
 355                                 free(pname);
 356                         }
 357
 358                         free(key);
 359                         free(value);
 360                 }
 361                 if (fclose(f))
 362                         perror("fclose");
 363
 364 next:
 365                 ++fd_path;
 366         }
 367         close_json_array(PRINT_JSON, NULL);
 368
 369         globfree(&globbuf);
 370 }
 371
 372 static int tuntap_filter_req(struct nlmsghdr *nlh, int reqlen)
 373 {
 374         struct rtattr *linkinfo;
 375         int err;
 376
 377         linkinfo = addattr_nest(nlh, reqlen, IFLA_LINKINFO);
 378
 379         err = addattr_l(nlh, reqlen, IFLA_INFO_KIND,
 380                         drv_name, sizeof(drv_name) - 1);
 381         if (err)
 382                 return err;
 383
 384         addattr_nest_end(nlh, linkinfo);
 385
 386         return 0;
 387 }
 388
 389 static int print_tuntap(const struct sockaddr_nl *who,
 390                         struct nlmsghdr *n, void *arg)
 391 {
 392         struct ifinfomsg *ifi = NLMSG_DATA(n);
 393         struct rtattr *tb[IFLA_MAX+1];
 394         struct rtattr *linkinfo[IFLA_INFO_MAX+1];
 395         const char *name, *kind;
 396         long flags, owner = -1, group = -1;
 397
 398         if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
 399                 return 0;
 400
 401         if (n->nlmsg_len < NLMSG_LENGTH(sizeof(*ifi)))
 402                 return -1;
 403
 404         switch (ifi->ifi_type) {
 405         case ARPHRD_NONE:
 406         case ARPHRD_ETHER:
 407                 break;
 408         default:
 409                 return 0;
 410         }
 411
 412         parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));
 413
 414         if (!tb[IFLA_IFNAME])
 415                 return 0;
 416
 417         if (!tb[IFLA_LINKINFO])
 418                 return 0;
 419
 420         parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
 421
 422         if (!linkinfo[IFLA_INFO_KIND])
 423                 return 0;
 424
 425         kind = rta_getattr_str(linkinfo[IFLA_INFO_KIND]);
 426         if (strcmp(kind, drv_name))
 427                 return 0;
 428
 429         name = rta_getattr_str(tb[IFLA_IFNAME]);
 430
 431         if (read_prop(name, "tun_flags", &flags))
 432                 return 0;
 433         if (read_prop(name, "owner", &owner))
 434                 return 0;
 435         if (read_prop(name, "group", &group))
 436                 return 0;
 437
 438         open_json_object(NULL);
 439         print_color_string(PRINT_ANY, COLOR_IFNAME,
 440                            "ifname", "%s:", name);
 441         print_flags(flags);
 442         if (owner != -1)
 443                 print_u64(PRINT_ANY, "user",
 444                            " user %ld", owner);
 445         if (group != -1)
 446                 print_u64(PRINT_ANY, "group",
 447                            " group %ld", group);
 448
 449         if (show_details) {
 450                 print_string(PRINT_FP, NULL,
 451                              "%s\tAttached to processes:", _SL_);
 452                 show_processes(name);
 453         }
 454         close_json_object();
 455         print_string(PRINT_FP, NULL, "%s", "\n");
 456
 457         return 0;
 458 }
 459
 460 static int do_show(int argc, char **argv)
 461 {
 462         if (rtnl_linkdump_req_filter_fn(&rth, AF_UNSPEC,
 463                                         tuntap_filter_req) < 0) {
 464                 perror("Cannot send dump request\n");
 465                 return -1;
 466         }
 467
 468         new_json_obj(json);
 469
 470         if (rtnl_dump_filter(&rth, print_tuntap, NULL) < 0) {
 471                 fprintf(stderr, "Dump terminated\n");
 472                 return -1;
 473         }
 474
 475         delete_json_obj();
 476         fflush(stdout);
 477
 478         return 0;
 479 }
 480
 481 int do_iptuntap(int argc, char **argv)
 482 {
 483         if (argc > 0) {
 484                 if (matches(*argv, "add") == 0)
 485                         return do_add(argc-1, argv+1);
 486                 if (matches(*argv, "delete") == 0)
 487                         return do_del(argc-1, argv+1);
 488                 if (matches(*argv, "show") == 0 ||
 489                     matches(*argv, "lst") == 0 ||
 490                     matches(*argv, "list") == 0)
 491                         return do_show(argc-1, argv+1);
 492                 if (matches(*argv, "help") == 0)
 493                         usage();
 494         } else
 495                 return do_show(0, NULL);
 496
 497         fprintf(stderr, "Command \"%s\" is unknown, try \"ip tuntap help\".\n",
 498                 *argv);
 499         exit(-1);
 500 }
 501
 502 static void print_owner(FILE *f, uid_t uid)
 503 {
 504         struct passwd *pw = getpwuid(uid);
 505
 506         if (pw)
 507                 print_string(PRINT_ANY, "user", "user %s ", pw->pw_name);
 508         else
 509                 print_uint(PRINT_ANY, "user", "user %u ", uid);
 510 }
 511
 512 static void print_group(FILE *f, gid_t gid)
 513 {
 514         struct group *group = getgrgid(gid);
 515
 516         if (group)
 517                 print_string(PRINT_ANY, "group", "group %s ", group->gr_name);
 518         else
 519                 print_uint(PRINT_ANY, "group", "group %u ", gid);
 520 }
 521
 522 static void print_mq(FILE *f, struct rtattr *tb[])
 523 {
 524         if (!tb[IFLA_TUN_MULTI_QUEUE] ||
 525             !rta_getattr_u8(tb[IFLA_TUN_MULTI_QUEUE])) {
 526                 if (is_json_context())
 527                         print_bool(PRINT_JSON, "multi_queue", NULL, false);
 528                 return;
 529         }
 530
 531         print_bool(PRINT_ANY, "multi_queue", "multi_queue ", true);
 532
 533         if (tb[IFLA_TUN_NUM_QUEUES]) {
 534                 print_uint(PRINT_ANY, "numqueues", "numqueues %u ",
 535                            rta_getattr_u32(tb[IFLA_TUN_NUM_QUEUES]));
 536         }
 537
 538         if (tb[IFLA_TUN_NUM_DISABLED_QUEUES]) {
 539                 print_uint(PRINT_ANY, "numdisabled", "numdisabled %u ",
 540                            rta_getattr_u32(tb[IFLA_TUN_NUM_DISABLED_QUEUES]));
 541         }
 542 }
 543
 544 static void print_onoff(FILE *f, const char *flag, __u8 val)
 545 {
 546         if (is_json_context())
 547                 print_bool(PRINT_JSON, flag, NULL, !!val);
 548         else
 549                 fprintf(f, "%s %s ", flag, val ? "on" : "off");
 550 }
 551
 552 static void print_type(FILE *f, __u8 type)
 553 {
 554         SPRINT_BUF(buf);
 555         const char *str = buf;
 556
 557         if (type == IFF_TUN)
 558                 str = "tun";
 559         else if (type == IFF_TAP)
 560                 str = "tap";
 561         else
 562                 snprintf(buf, sizeof(buf), "UNKNOWN:%hhu", type);
 563
 564         print_string(PRINT_ANY, "type", "type %s ", str);
 565 }
 566
 567 static void tun_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 568 {
 569         if (!tb)
 570                 return;
 571
 572         if (tb[IFLA_TUN_TYPE])
 573                 print_type(f, rta_getattr_u8(tb[IFLA_TUN_TYPE]));
 574
 575         if (tb[IFLA_TUN_PI])
 576                 print_onoff(f, "pi", rta_getattr_u8(tb[IFLA_TUN_PI]));
 577
 578         if (tb[IFLA_TUN_VNET_HDR]) {
 579                 print_onoff(f, "vnet_hdr",
 580                             rta_getattr_u8(tb[IFLA_TUN_VNET_HDR]));
 581         }
 582
 583         print_mq(f, tb);
 584
 585         if (tb[IFLA_TUN_PERSIST])
 586                 print_onoff(f, "persist", rta_getattr_u8(tb[IFLA_TUN_PERSIST]));
 587
 588         if (tb[IFLA_TUN_OWNER])
 589                 print_owner(f, rta_getattr_u32(tb[IFLA_TUN_OWNER]));
 590
 591         if (tb[IFLA_TUN_GROUP])
 592                 print_group(f, rta_getattr_u32(tb[IFLA_TUN_GROUP]));
 593 }
 594
 595 struct link_util tun_link_util = {
 596         .id = "tun",
 597         .maxattr = IFLA_TUN_MAX,
 598         .print_opt = tun_print_opt,
 599 };