1 /* 2 * Copyright (c) 2005 Reyk Floeter <reyk (at) openbsd.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 #include "includes.h" 18 19 #include <sys/types.h> 20 #include <sys/ioctl.h> 21 22 #include <netinet/in.h> 23 #include <arpa/inet.h> 24 #include <netinet/ip.h> 25 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <stdarg.h> 29 #include <string.h> 30 #include <unistd.h> 31 32 #include "openbsd-compat/sys-queue.h" 33 #include "log.h" 34 #include "misc.h" 35 #include "buffer.h" 36 #include "channels.h" 37 38 /* 39 * This is the portable version of the SSH tunnel forwarding, it 40 * uses some preprocessor definitions for various platform-specific 41 * settings. 42 * 43 * SSH_TUN_LINUX Use the (newer) Linux tun/tap device 44 * SSH_TUN_FREEBSD Use the FreeBSD tun/tap device 45 * SSH_TUN_COMPAT_AF Translate the OpenBSD address family 46 * SSH_TUN_PREPEND_AF Prepend/remove the address family 47 */ 48 49 /* 50 * System-specific tunnel open function 51 */ 52 53 #if defined(SSH_TUN_LINUX) 54 #include <linux/if.h> 55 #include <linux/if_tun.h> 56 57 int 58 sys_tun_open(int tun, int mode) 59 { 60 struct ifreq ifr; 61 int fd = -1; 62 const char *name = NULL; 63 64 if ((fd = open("/dev/net/tun", O_RDWR)) == -1) { 65 debug("%s: failed to open tunnel control interface: %s", 66 __func__, strerror(errno)); 67 return (-1); 68 } 69 70 bzero(&ifr, sizeof(ifr)); 71 72 if (mode == SSH_TUNMODE_ETHERNET) { 73 ifr.ifr_flags = IFF_TAP; 74 name = "tap%d"; 75 } else { 76 ifr.ifr_flags = IFF_TUN; 77 name = "tun%d"; 78 } 79 ifr.ifr_flags |= IFF_NO_PI; 80 81 if (tun != SSH_TUNID_ANY) { 82 if (tun > SSH_TUNID_MAX) { 83 debug("%s: invalid tunnel id %x: %s", __func__, 84 tun, strerror(errno)); 85 goto failed; 86 } 87 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun); 88 } 89 90 if (ioctl(fd, TUNSETIFF, &ifr) == -1) { 91 debug("%s: failed to configure tunnel (mode %d): %s", __func__, 92 mode, strerror(errno)); 93 goto failed; 94 } 95 96 if (tun == SSH_TUNID_ANY) 97 debug("%s: tunnel mode %d fd %d", __func__, mode, fd); 98 else 99 debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd); 100 101 return (fd); 102 103 failed: 104 close(fd); 105 return (-1); 106 } 107 #endif /* SSH_TUN_LINUX */ 108 109 #ifdef SSH_TUN_FREEBSD 110 #include <sys/socket.h> 111 #include <net/if.h> 112 113 #ifdef HAVE_NET_IF_TUN_H 114 #include <net/if_tun.h> 115 #endif 116 117 int 118 sys_tun_open(int tun, int mode) 119 { 120 struct ifreq ifr; 121 char name[100]; 122 int fd = -1, sock, flag; 123 const char *tunbase = "tun"; 124 125 if (mode == SSH_TUNMODE_ETHERNET) { 126 #ifdef SSH_TUN_NO_L2 127 debug("%s: no layer 2 tunnelling support", __func__); 128 return (-1); 129 #else 130 tunbase = "tap"; 131 #endif 132 } 133 134 /* Open the tunnel device */ 135 if (tun <= SSH_TUNID_MAX) { 136 snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun); 137 fd = open(name, O_RDWR); 138 } else if (tun == SSH_TUNID_ANY) { 139 for (tun = 100; tun >= 0; tun--) { 140 snprintf(name, sizeof(name), "/dev/%s%d", 141 tunbase, tun); 142 if ((fd = open(name, O_RDWR)) >= 0) 143 break; 144 } 145 } else { 146 debug("%s: invalid tunnel %u\n", __func__, tun); 147 return (-1); 148 } 149 150 if (fd < 0) { 151 debug("%s: %s open failed: %s", __func__, name, 152 strerror(errno)); 153 return (-1); 154 } 155 156 /* Turn on tunnel headers */ 157 flag = 1; 158 #if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF) 159 if (mode != SSH_TUNMODE_ETHERNET && 160 ioctl(fd, TUNSIFHEAD, &flag) == -1) { 161 debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd, 162 strerror(errno)); 163 close(fd); 164 } 165 #endif 166 167 debug("%s: %s mode %d fd %d", __func__, name, mode, fd); 168 169 /* Set the tunnel device operation mode */ 170 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun); 171 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 172 goto failed; 173 174 if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1) 175 goto failed; 176 if ((ifr.ifr_flags & IFF_UP) == 0) { 177 ifr.ifr_flags |= IFF_UP; 178 if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1) 179 goto failed; 180 } 181 182 close(sock); 183 return (fd); 184 185 failed: 186 if (fd >= 0) 187 close(fd); 188 if (sock >= 0) 189 close(sock); 190 debug("%s: failed to set %s mode %d: %s", __func__, name, 191 mode, strerror(errno)); 192 return (-1); 193 } 194 #endif /* SSH_TUN_FREEBSD */ 195 196 /* 197 * System-specific channel filters 198 */ 199 200 #if defined(SSH_TUN_FILTER) 201 #define OPENBSD_AF_INET 2 202 #define OPENBSD_AF_INET6 24 203 204 int 205 sys_tun_infilter(struct Channel *c, char *buf, int len) 206 { 207 #if defined(SSH_TUN_PREPEND_AF) 208 char rbuf[CHAN_RBUF]; 209 struct ip *iph; 210 #endif 211 u_int32_t *af; 212 char *ptr = buf; 213 214 #if defined(SSH_TUN_PREPEND_AF) 215 if (len <= 0 || len > (int)(sizeof(rbuf) - sizeof(*af))) 216 return (-1); 217 ptr = (char *)&rbuf[0]; 218 bcopy(buf, ptr + sizeof(u_int32_t), len); 219 len += sizeof(u_int32_t); 220 af = (u_int32_t *)ptr; 221 222 iph = (struct ip *)(ptr + sizeof(u_int32_t)); 223 switch (iph->ip_v) { 224 case 6: 225 *af = AF_INET6; 226 break; 227 case 4: 228 default: 229 *af = AF_INET; 230 break; 231 } 232 #endif 233 234 #if defined(SSH_TUN_COMPAT_AF) 235 if (len < (int)sizeof(u_int32_t)) 236 return (-1); 237 238 af = (u_int32_t *)ptr; 239 if (*af == htonl(AF_INET6)) 240 *af = htonl(OPENBSD_AF_INET6); 241 else 242 *af = htonl(OPENBSD_AF_INET); 243 #endif 244 245 buffer_put_string(&c->input, ptr, len); 246 return (0); 247 } 248 249 u_char * 250 sys_tun_outfilter(struct Channel *c, u_char **data, u_int *dlen) 251 { 252 u_char *buf; 253 u_int32_t *af; 254 255 *data = buffer_get_string(&c->output, dlen); 256 if (*dlen < sizeof(*af)) 257 return (NULL); 258 buf = *data; 259 260 #if defined(SSH_TUN_PREPEND_AF) 261 *dlen -= sizeof(u_int32_t); 262 buf = *data + sizeof(u_int32_t); 263 #elif defined(SSH_TUN_COMPAT_AF) 264 af = ntohl(*(u_int32_t *)buf); 265 if (*af == OPENBSD_AF_INET6) 266 *af = htonl(AF_INET6); 267 else 268 *af = htonl(AF_INET); 269 #endif 270 271 return (buf); 272 } 273 #endif /* SSH_TUN_FILTER */ 274
