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      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 (at) 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 }
    325