| 1 | /* |
| 2 | * Functions for looking up the remote name or addr of a socket. |
| 3 | * |
| 4 | * Copyright (C) 1992-2001 Andrew Tridgell <tridge@samba.org> |
| 5 | * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org> |
| 6 | * Copyright (C) 2002-2007 Wayne Davison |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation; either version 3 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License along |
| 19 | * with this program; if not, visit the http://fsf.org website. |
| 20 | */ |
| 21 | |
| 22 | /* |
| 23 | * This file is now converted to use the new-style getaddrinfo() |
| 24 | * interface, which supports IPv6 but is also supported on recent |
| 25 | * IPv4-only machines. On systems that don't have that interface, we |
| 26 | * emulate it using the KAME implementation. |
| 27 | */ |
| 28 | |
| 29 | #include "rsync.h" |
| 30 | |
| 31 | static const char default_name[] = "UNKNOWN"; |
| 32 | extern int am_server; |
| 33 | |
| 34 | |
| 35 | /** |
| 36 | * Return the IP addr of the client as a string |
| 37 | **/ |
| 38 | char *client_addr(int fd) |
| 39 | { |
| 40 | static char addr_buf[100]; |
| 41 | static int initialised; |
| 42 | struct sockaddr_storage ss; |
| 43 | socklen_t length = sizeof ss; |
| 44 | char *ssh_info, *p; |
| 45 | |
| 46 | if (initialised) |
| 47 | return addr_buf; |
| 48 | |
| 49 | initialised = 1; |
| 50 | |
| 51 | if (am_server) { /* daemon over --rsh mode */ |
| 52 | strlcpy(addr_buf, "0.0.0.0", sizeof addr_buf); |
| 53 | if ((ssh_info = getenv("SSH_CONNECTION")) != NULL |
| 54 | || (ssh_info = getenv("SSH_CLIENT")) != NULL |
| 55 | || (ssh_info = getenv("SSH2_CLIENT")) != NULL) { |
| 56 | strlcpy(addr_buf, ssh_info, sizeof addr_buf); |
| 57 | /* Truncate the value to just the IP address. */ |
| 58 | if ((p = strchr(addr_buf, ' ')) != NULL) |
| 59 | *p = '\0'; |
| 60 | } |
| 61 | } else { |
| 62 | client_sockaddr(fd, &ss, &length); |
| 63 | getnameinfo((struct sockaddr *)&ss, length, |
| 64 | addr_buf, sizeof addr_buf, NULL, 0, NI_NUMERICHOST); |
| 65 | } |
| 66 | |
| 67 | return addr_buf; |
| 68 | } |
| 69 | |
| 70 | |
| 71 | static int get_sockaddr_family(const struct sockaddr_storage *ss) |
| 72 | { |
| 73 | return ((struct sockaddr *) ss)->sa_family; |
| 74 | } |
| 75 | |
| 76 | |
| 77 | /** |
| 78 | * Return the DNS name of the client. |
| 79 | * |
| 80 | * The name is statically cached so that repeated lookups are quick, |
| 81 | * so there is a limit of one lookup per customer. |
| 82 | * |
| 83 | * If anything goes wrong, including the name->addr->name check, then |
| 84 | * we just use "UNKNOWN", so you can use that value in hosts allow |
| 85 | * lines. |
| 86 | * |
| 87 | * After translation from sockaddr to name we do a forward lookup to |
| 88 | * make sure nobody is spoofing PTR records. |
| 89 | **/ |
| 90 | char *client_name(int fd) |
| 91 | { |
| 92 | static char name_buf[100]; |
| 93 | static char port_buf[100]; |
| 94 | static int initialised; |
| 95 | struct sockaddr_storage ss; |
| 96 | socklen_t ss_len; |
| 97 | |
| 98 | if (initialised) |
| 99 | return name_buf; |
| 100 | |
| 101 | strlcpy(name_buf, default_name, sizeof name_buf); |
| 102 | initialised = 1; |
| 103 | |
| 104 | memset(&ss, 0, sizeof ss); |
| 105 | |
| 106 | if (am_server) { /* daemon over --rsh mode */ |
| 107 | char *addr = client_addr(fd); |
| 108 | struct addrinfo hint, *answer; |
| 109 | int err; |
| 110 | |
| 111 | memset(&hint, 0, sizeof hint); |
| 112 | |
| 113 | #ifdef AI_NUMERICHOST |
| 114 | hint.ai_flags = AI_NUMERICHOST; |
| 115 | #endif |
| 116 | hint.ai_socktype = SOCK_STREAM; |
| 117 | |
| 118 | if ((err = getaddrinfo(addr, NULL, &hint, &answer)) != 0) { |
| 119 | rprintf(FLOG, "malformed address %s: %s\n", |
| 120 | addr, gai_strerror(err)); |
| 121 | return name_buf; |
| 122 | } |
| 123 | |
| 124 | switch (answer->ai_family) { |
| 125 | case AF_INET: |
| 126 | ss_len = sizeof (struct sockaddr_in); |
| 127 | memcpy(&ss, answer->ai_addr, ss_len); |
| 128 | break; |
| 129 | #ifdef INET6 |
| 130 | case AF_INET6: |
| 131 | ss_len = sizeof (struct sockaddr_in6); |
| 132 | memcpy(&ss, answer->ai_addr, ss_len); |
| 133 | break; |
| 134 | #endif |
| 135 | default: |
| 136 | exit_cleanup(RERR_SOCKETIO); |
| 137 | } |
| 138 | freeaddrinfo(answer); |
| 139 | } else { |
| 140 | ss_len = sizeof ss; |
| 141 | client_sockaddr(fd, &ss, &ss_len); |
| 142 | } |
| 143 | |
| 144 | if (lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, |
| 145 | port_buf, sizeof port_buf) == 0) |
| 146 | check_name(fd, &ss, name_buf, sizeof name_buf); |
| 147 | |
| 148 | return name_buf; |
| 149 | } |
| 150 | |
| 151 | |
| 152 | |
| 153 | /** |
| 154 | * Get the sockaddr for the client. |
| 155 | * |
| 156 | * If it comes in as an ipv4 address mapped into IPv6 format then we |
| 157 | * convert it back to a regular IPv4. |
| 158 | **/ |
| 159 | void client_sockaddr(int fd, |
| 160 | struct sockaddr_storage *ss, |
| 161 | socklen_t *ss_len) |
| 162 | { |
| 163 | memset(ss, 0, sizeof *ss); |
| 164 | |
| 165 | if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { |
| 166 | /* FIXME: Can we really not continue? */ |
| 167 | rsyserr(FLOG, errno, "getpeername on fd%d failed", fd); |
| 168 | exit_cleanup(RERR_SOCKETIO); |
| 169 | } |
| 170 | |
| 171 | #ifdef INET6 |
| 172 | if (get_sockaddr_family(ss) == AF_INET6 && |
| 173 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { |
| 174 | /* OK, so ss is in the IPv6 family, but it is really |
| 175 | * an IPv4 address: something like |
| 176 | * "::ffff:10.130.1.2". If we use it as-is, then the |
| 177 | * reverse lookup might fail or perhaps something else |
| 178 | * bad might happen. So instead we convert it to an |
| 179 | * equivalent address in the IPv4 address family. */ |
| 180 | struct sockaddr_in6 sin6; |
| 181 | struct sockaddr_in *sin; |
| 182 | |
| 183 | memcpy(&sin6, ss, sizeof sin6); |
| 184 | sin = (struct sockaddr_in *)ss; |
| 185 | memset(sin, 0, sizeof *sin); |
| 186 | sin->sin_family = AF_INET; |
| 187 | *ss_len = sizeof (struct sockaddr_in); |
| 188 | #ifdef HAVE_SOCKADDR_IN_LEN |
| 189 | sin->sin_len = *ss_len; |
| 190 | #endif |
| 191 | sin->sin_port = sin6.sin6_port; |
| 192 | |
| 193 | /* There is a macro to extract the mapped part |
| 194 | * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem |
| 195 | * to be present in the Linux headers. */ |
| 196 | memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], |
| 197 | sizeof sin->sin_addr); |
| 198 | } |
| 199 | #endif |
| 200 | } |
| 201 | |
| 202 | |
| 203 | /** |
| 204 | * Look up a name from @p ss into @p name_buf. |
| 205 | * |
| 206 | * @param fd file descriptor for client socket. |
| 207 | **/ |
| 208 | int lookup_name(int fd, const struct sockaddr_storage *ss, |
| 209 | socklen_t ss_len, |
| 210 | char *name_buf, size_t name_buf_size, |
| 211 | char *port_buf, size_t port_buf_size) |
| 212 | { |
| 213 | int name_err; |
| 214 | |
| 215 | /* reverse lookup */ |
| 216 | name_err = getnameinfo((struct sockaddr *) ss, ss_len, |
| 217 | name_buf, name_buf_size, |
| 218 | port_buf, port_buf_size, |
| 219 | NI_NAMEREQD | NI_NUMERICSERV); |
| 220 | if (name_err != 0) { |
| 221 | strlcpy(name_buf, default_name, name_buf_size); |
| 222 | rprintf(FLOG, "name lookup failed for %s: %s\n", |
| 223 | client_addr(fd), gai_strerror(name_err)); |
| 224 | return name_err; |
| 225 | } |
| 226 | |
| 227 | return 0; |
| 228 | } |
| 229 | |
| 230 | |
| 231 | |
| 232 | /** |
| 233 | * Compare an addrinfo from the resolver to a sockinfo. |
| 234 | * |
| 235 | * Like strcmp, returns 0 for identical. |
| 236 | **/ |
| 237 | int compare_addrinfo_sockaddr(const struct addrinfo *ai, |
| 238 | const struct sockaddr_storage *ss) |
| 239 | { |
| 240 | int ss_family = get_sockaddr_family(ss); |
| 241 | const char fn[] = "compare_addrinfo_sockaddr"; |
| 242 | |
| 243 | if (ai->ai_family != ss_family) { |
| 244 | rprintf(FLOG, "%s: response family %d != %d\n", |
| 245 | fn, ai->ai_family, ss_family); |
| 246 | return 1; |
| 247 | } |
| 248 | |
| 249 | /* The comparison method depends on the particular AF. */ |
| 250 | if (ss_family == AF_INET) { |
| 251 | const struct sockaddr_in *sin1, *sin2; |
| 252 | |
| 253 | sin1 = (const struct sockaddr_in *) ss; |
| 254 | sin2 = (const struct sockaddr_in *) ai->ai_addr; |
| 255 | |
| 256 | return memcmp(&sin1->sin_addr, &sin2->sin_addr, |
| 257 | sizeof sin1->sin_addr); |
| 258 | } |
| 259 | |
| 260 | #ifdef INET6 |
| 261 | if (ss_family == AF_INET6) { |
| 262 | const struct sockaddr_in6 *sin1, *sin2; |
| 263 | |
| 264 | sin1 = (const struct sockaddr_in6 *) ss; |
| 265 | sin2 = (const struct sockaddr_in6 *) ai->ai_addr; |
| 266 | |
| 267 | if (ai->ai_addrlen < sizeof (struct sockaddr_in6)) { |
| 268 | rprintf(FLOG, "%s: too short sockaddr_in6; length=%d\n", |
| 269 | fn, ai->ai_addrlen); |
| 270 | return 1; |
| 271 | } |
| 272 | |
| 273 | if (memcmp(&sin1->sin6_addr, &sin2->sin6_addr, |
| 274 | sizeof sin1->sin6_addr)) |
| 275 | return 1; |
| 276 | |
| 277 | #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID |
| 278 | if (sin1->sin6_scope_id != sin2->sin6_scope_id) |
| 279 | return 1; |
| 280 | #endif |
| 281 | return 0; |
| 282 | } |
| 283 | #endif /* INET6 */ |
| 284 | |
| 285 | /* don't know */ |
| 286 | return 1; |
| 287 | } |
| 288 | |
| 289 | |
| 290 | /** |
| 291 | * Do a forward lookup on @p name_buf and make sure it corresponds to |
| 292 | * @p ss -- otherwise we may be being spoofed. If we suspect we are, |
| 293 | * then we don't abort the connection but just emit a warning, and |
| 294 | * change @p name_buf to be "UNKNOWN". |
| 295 | * |
| 296 | * We don't do anything with the service when checking the name, |
| 297 | * because it doesn't seem that it could be spoofed in any way, and |
| 298 | * getaddrinfo on random service names seems to cause problems on AIX. |
| 299 | **/ |
| 300 | int check_name(int fd, |
| 301 | const struct sockaddr_storage *ss, |
| 302 | char *name_buf, size_t name_buf_size) |
| 303 | { |
| 304 | struct addrinfo hints, *res, *res0; |
| 305 | int error; |
| 306 | int ss_family = get_sockaddr_family(ss); |
| 307 | |
| 308 | memset(&hints, 0, sizeof hints); |
| 309 | hints.ai_family = ss_family; |
| 310 | hints.ai_flags = AI_CANONNAME; |
| 311 | hints.ai_socktype = SOCK_STREAM; |
| 312 | error = getaddrinfo(name_buf, NULL, &hints, &res0); |
| 313 | if (error) { |
| 314 | rprintf(FLOG, "forward name lookup for %s failed: %s\n", |
| 315 | name_buf, gai_strerror(error)); |
| 316 | strlcpy(name_buf, default_name, name_buf_size); |
| 317 | return error; |
| 318 | } |
| 319 | |
| 320 | /* Given all these results, we expect that one of them will be |
| 321 | * the same as ss. The comparison is a bit complicated. */ |
| 322 | for (res = res0; res; res = res->ai_next) { |
| 323 | if (!compare_addrinfo_sockaddr(res, ss)) |
| 324 | break; /* OK, identical */ |
| 325 | } |
| 326 | |
| 327 | if (!res0) { |
| 328 | /* We hit the end of the list without finding an |
| 329 | * address that was the same as ss. */ |
| 330 | rprintf(FLOG, "no known address for \"%s\": " |
| 331 | "spoofed address?\n", name_buf); |
| 332 | strlcpy(name_buf, default_name, name_buf_size); |
| 333 | } else if (res == NULL) { |
| 334 | /* We hit the end of the list without finding an |
| 335 | * address that was the same as ss. */ |
| 336 | rprintf(FLOG, "%s is not a known address for \"%s\": " |
| 337 | "spoofed address?\n", client_addr(fd), name_buf); |
| 338 | strlcpy(name_buf, default_name, name_buf_size); |
| 339 | } |
| 340 | |
| 341 | freeaddrinfo(res0); |
| 342 | return 0; |
| 343 | } |