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 <pwd.h>
  24 #include <grp.h>
  25 #include <fcntl.h>
  26 #include <dirent.h>
  27 #include <errno.h>
  28
  29 #include "rt_names.h"
  30 #include "utils.h"
  31 #include "ip_common.h"
  32
  33 #define TUNDEV "/dev/net/tun"
  34
  35 static void usage(void) __attribute__((noreturn));
  36
  37 static void usage(void)
  38 {
  39         fprintf(stderr, "Usage: ip tuntap { add | del } [ dev PHYS_DEV ] \n");
  40         fprintf(stderr, "          [ mode { tun | tap } ] [ user USER ] [ group GROUP ]\n");
  41         fprintf(stderr, "          [ one_queue ] [ pi ] [ vnet_hdr ]\n");
  42         fprintf(stderr, "\n");
  43         fprintf(stderr, "Where: USER  := { STRING | NUMBER }\n");
  44         fprintf(stderr, "       GROUP := { STRING | NUMBER }\n");
  45         exit(-1);
  46 }
  47
  48 static int tap_add_ioctl(struct ifreq *ifr, uid_t uid, gid_t gid)
  49 {
  50         int fd;
  51         int ret = -1;
  52
  53 #ifdef IFF_TUN_EXCL
  54         ifr->ifr_flags |= IFF_TUN_EXCL;
  55 #endif
  56
  57         fd = open(TUNDEV, O_RDWR);
  58         if (fd < 0) {
  59                 perror("open");
  60                 return -1;
  61         }
  62         if (ioctl(fd, TUNSETIFF, ifr)) {
  63                 perror("ioctl(TUNSETIFF)");
  64                 goto out;
  65         }
  66         if (uid != -1 && ioctl(fd, TUNSETOWNER, uid)) {
  67                 perror("ioctl(TUNSETOWNER)");
  68                 goto out;
  69         }
  70         if (gid != -1 && ioctl(fd, TUNSETGROUP, gid)) {
  71                 perror("ioctl(TUNSETGROUP)");
  72                 goto out;
  73         }
  74         if (ioctl(fd, TUNSETPERSIST, 1)) {
  75                 perror("ioctl(TUNSETPERSIST)");
  76                 goto out;
  77         }
  78         ret = 0;
  79  out:
  80         close(fd);
  81         return ret;
  82 }
  83
  84 static int tap_del_ioctl(struct ifreq *ifr)
  85 {
  86         int fd = open(TUNDEV, O_RDWR);
  87         int ret = -1;
  88
  89         if (fd < 0) {
  90                 perror("open");
  91                 return -1;
  92         }
  93         if (ioctl(fd, TUNSETIFF, ifr)) {
  94                 perror("ioctl(TUNSETIFF)");
  95                 goto out;
  96         }
  97         if (ioctl(fd, TUNSETPERSIST, 0)) {
  98                 perror("ioctl(TUNSETPERSIST)");
  99                 goto out;
 100         }
 101         ret = 0;
 102  out:
 103         close(fd);
 104         return ret;
 105
 106 }
 107 static int parse_args(int argc, char **argv, struct ifreq *ifr, uid_t *uid, gid_t *gid)
 108 {
 109         int count = 0;
 110
 111         memset(ifr, 0, sizeof(*ifr));
 112
 113         ifr->ifr_flags |= IFF_NO_PI;
 114
 115         while (argc > 0) {
 116                 if (matches(*argv, "mode") == 0) {
 117                         NEXT_ARG();
 118                         if (matches(*argv, "tun") == 0) {
 119                                 if (ifr->ifr_flags & IFF_TAP) {
 120                                         fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
 121                                         exit(-1);
 122                                 }
 123                                 ifr->ifr_flags |= IFF_TUN;
 124                         } else if (matches(*argv, "tap") == 0) {
 125                                 if (ifr->ifr_flags & IFF_TUN) {
 126                                         fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
 127                                         exit(-1);
 128                                 }
 129                                 ifr->ifr_flags |= IFF_TAP;
 130                         } else {
 131                                 fprintf(stderr,"Cannot guess tunnel mode.\n");
 132                                 exit(-1);
 133                         }
 134                 } else if (uid && matches(*argv, "user") == 0) {
 135                         char *end;
 136                         unsigned long user;
 137
 138                         NEXT_ARG();
 139                         if (**argv && ((user = strtol(*argv, &end, 10)), !*end))
 140                                 *uid = user;
 141                         else {
 142                                 struct passwd *pw = getpwnam(*argv);
 143                                 if (!pw) {
 144                                         fprintf(stderr, "invalid user \"%s\"\n", *argv);
 145                                         exit(-1);
 146                                 }
 147                                 *uid = pw->pw_uid;
 148                         }
 149                 } else if (gid && matches(*argv, "group") == 0) {
 150                         char *end;
 151                         unsigned long group;
 152
 153                         NEXT_ARG();
 154
 155                         if (**argv && ((group = strtol(*argv, &end, 10)), !*end))
 156                                 *gid = group;
 157                         else {
 158                                 struct group *gr = getgrnam(*argv);
 159                                 if (!gr) {
 160                                         fprintf(stderr, "invalid group \"%s\"\n", *argv);
 161                                         exit(-1);
 162                                 }
 163                                 *gid = gr->gr_gid;
 164                         }
 165                 } else if (matches(*argv, "pi") == 0) {
 166                         ifr->ifr_flags &= ~IFF_NO_PI;
 167                 } else if (matches(*argv, "one_queue") == 0) {
 168                         ifr->ifr_flags |= IFF_ONE_QUEUE;
 169                 } else if (matches(*argv, "vnet_hdr") == 0) {
 170                         ifr->ifr_flags |= IFF_VNET_HDR;
 171                 } else if (matches(*argv, "dev") == 0) {
 172                         NEXT_ARG();
 173                         strncpy(ifr->ifr_name, *argv, IFNAMSIZ-1);
 174                 } else {
 175                         if (matches(*argv, "name") == 0) {
 176                                 NEXT_ARG();
 177                         } else if (matches(*argv, "help") == 0)
 178                                 usage();
 179                         if (ifr->ifr_name[0])
 180                                 duparg2("name", *argv);
 181                         strncpy(ifr->ifr_name, *argv, IFNAMSIZ);
 182                 }
 183                 count++;
 184                 argc--; argv++;
 185         }
 186
 187         return 0;
 188 }
 189
 190
 191 static int do_add(int argc, char **argv)
 192 {
 193         struct ifreq ifr;
 194         uid_t uid = -1;
 195         gid_t gid = -1;
 196
 197         if (parse_args(argc, argv, &ifr, &uid, &gid) < 0)
 198                 return -1;
 199
 200         if (!(ifr.ifr_flags & TUN_TYPE_MASK)) {
 201                 fprintf(stderr, "You failed to specify a tunnel mode\n");
 202                 return -1;
 203         }
 204         return tap_add_ioctl(&ifr, uid, gid);
 205 }
 206
 207 static int do_del(int argc, char **argv)
 208 {
 209         struct ifreq ifr;
 210
 211         if (parse_args(argc, argv, &ifr, NULL, NULL) < 0)
 212                 return -1;
 213
 214         return tap_del_ioctl(&ifr);
 215 }
 216
 217 static int read_prop(char *dev, char *prop, long *value)
 218 {
 219         char fname[IFNAMSIZ+25], buf[80], *endp;
 220         ssize_t len;
 221         int fd;
 222         long result;
 223
 224         sprintf(fname, "/sys/class/net/%s/%s", dev, prop);
 225         fd = open(fname, O_RDONLY);
 226         if (fd < 0) {
 227                 if (strcmp(prop, "tun_flags"))
 228                         fprintf(stderr, "open %s: %s\n", fname,
 229                                 strerror(errno));
 230                 return -1;
 231         }
 232         len = read(fd, buf, sizeof(buf)-1);
 233         close(fd);
 234         if (len < 0) {
 235                 fprintf(stderr, "read %s: %s", fname, strerror(errno));
 236                 return -1;
 237         }
 238
 239         buf[len] = 0;
 240         result = strtol(buf, &endp, 0);
 241         if (*endp != '\n') {
 242                 fprintf(stderr, "Failed to parse %s\n", fname);
 243                 return -1;
 244         }
 245         *value = result;
 246         return 0;
 247 }
 248
 249 static void print_flags(long flags)
 250 {
 251         if (flags & IFF_TUN)
 252                 printf(" tun");
 253
 254         if (flags & IFF_TAP)
 255                 printf(" tap");
 256
 257         if (!(flags & IFF_NO_PI))
 258                 printf(" pi");
 259
 260         if (flags & IFF_ONE_QUEUE)
 261                 printf(" one_queue");
 262
 263         if (flags & IFF_VNET_HDR)
 264                 printf(" vnet_hdr");
 265
 266         flags &= ~(IFF_TUN|IFF_TAP|IFF_NO_PI|IFF_ONE_QUEUE|IFF_VNET_HDR);
 267         if (flags)
 268                 printf(" UNKNOWN_FLAGS:%lx", flags);
 269 }
 270
 271 static int do_show(int argc, char **argv)
 272 {
 273         DIR *dir;
 274         struct dirent *d;
 275         long flags, owner = -1, group = -1;
 276
 277         dir = opendir("/sys/class/net");
 278         if (!dir) {
 279                 perror("opendir");
 280                 return -1;
 281         }
 282         while ((d = readdir(dir))) {
 283                 if (d->d_name[0] == '.' &&
 284                     (d->d_name[1] == 0 || d->d_name[1] == '.'))
 285                         continue;
 286
 287                 if (read_prop(d->d_name, "tun_flags", &flags))
 288                         continue;
 289
 290                 read_prop(d->d_name, "owner", &owner);
 291                 read_prop(d->d_name, "group", &group);
 292
 293                 printf("%s:", d->d_name);
 294                 print_flags(flags);
 295                 if (owner != -1)
 296                         printf(" user %ld", owner);
 297                 if (group != -1)
 298                         printf(" group %ld", group);
 299                 printf("\n");
 300         }
 301         closedir(dir);
 302         return 0;
 303 }
 304
 305 int do_iptuntap(int argc, char **argv)
 306 {
 307         if (argc > 0) {
 308                 if (matches(*argv, "add") == 0)
 309                         return do_add(argc-1, argv+1);
 310                 if (matches(*argv, "del") == 0)
 311                         return do_del(argc-1, argv+1);
 312                 if (matches(*argv, "show") == 0 ||
 313                     matches(*argv, "lst") == 0 ||
 314                     matches(*argv, "list") == 0)
 315                         return do_show(argc-1, argv+1);
 316                 if (matches(*argv, "help") == 0)
 317                         usage();
 318         } else
 319                 return do_show(0, NULL);
 320
 321         fprintf(stderr, "Command \"%s\" is unknown, try \"ip tuntap help\".\n",
 322                 *argv);
 323         exit(-1);
 324 }