| 1 | /* -*- c-file-style: "linux" -*- |
| 2 | |
| 3 | rsync -- fast file replication program |
| 4 | |
| 5 | Copyright (C) 1992-2001 by Andrew Tridgell <tridge@samba.org> |
| 6 | Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org> |
| 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 2 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 |
| 19 | along with this program; if not, write to the Free Software |
| 20 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 21 | */ |
| 22 | |
| 23 | /** |
| 24 | * @file clientname.c |
| 25 | * |
| 26 | * Functions for looking up the remote name or addr of a socket. |
| 27 | * |
| 28 | * This file is now converted to use the new-style getaddrinfo() |
| 29 | * interface, which supports IPv6 but is also supported on recent |
| 30 | * IPv4-only machines. On systems that don't have that interface, we |
| 31 | * emulate it using the KAME implementation. |
| 32 | **/ |
| 33 | |
| 34 | #include "rsync.h" |
| 35 | |
| 36 | static const char default_name[] = "UNKNOWN"; |
| 37 | |
| 38 | |
| 39 | /** |
| 40 | * Return the IP addr of the client as a string |
| 41 | **/ |
| 42 | char *client_addr(int fd) |
| 43 | { |
| 44 | struct sockaddr_storage ss; |
| 45 | socklen_t length = sizeof ss; |
| 46 | static char addr_buf[100]; |
| 47 | static int initialised; |
| 48 | |
| 49 | if (initialised) return addr_buf; |
| 50 | |
| 51 | initialised = 1; |
| 52 | |
| 53 | client_sockaddr(fd, &ss, &length); |
| 54 | |
| 55 | getnameinfo((struct sockaddr *)&ss, length, |
| 56 | addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST); |
| 57 | |
| 58 | return addr_buf; |
| 59 | } |
| 60 | |
| 61 | |
| 62 | static int get_sockaddr_family(const struct sockaddr_storage *ss) |
| 63 | { |
| 64 | return ((struct sockaddr *) ss)->sa_family; |
| 65 | } |
| 66 | |
| 67 | |
| 68 | /** |
| 69 | * Return the DNS name of the client. |
| 70 | * |
| 71 | * The name is statically cached so that repeated lookups are quick, |
| 72 | * so there is a limit of one lookup per customer. |
| 73 | * |
| 74 | * If anything goes wrong, including the name->addr->name check, then |
| 75 | * we just use "UNKNOWN", so you can use that value in hosts allow |
| 76 | * lines. |
| 77 | **/ |
| 78 | char *client_name(int fd) |
| 79 | { |
| 80 | struct sockaddr_storage ss; |
| 81 | socklen_t ss_len = sizeof ss; |
| 82 | static char name_buf[100]; |
| 83 | static char port_buf[100]; |
| 84 | static int initialised; |
| 85 | |
| 86 | if (initialised) return name_buf; |
| 87 | |
| 88 | strcpy(name_buf, default_name); |
| 89 | initialised = 1; |
| 90 | |
| 91 | client_sockaddr(fd, &ss, &ss_len); |
| 92 | |
| 93 | if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, port_buf, sizeof port_buf)) |
| 94 | check_name(fd, &ss, name_buf, port_buf); |
| 95 | |
| 96 | return name_buf; |
| 97 | } |
| 98 | |
| 99 | |
| 100 | |
| 101 | /** |
| 102 | * Get the sockaddr for the client. |
| 103 | * |
| 104 | * If it comes in as an ipv4 address mapped into IPv6 format then we |
| 105 | * convert it back to a regular IPv4. |
| 106 | **/ |
| 107 | void client_sockaddr(int fd, |
| 108 | struct sockaddr_storage *ss, |
| 109 | socklen_t *ss_len) |
| 110 | { |
| 111 | if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { |
| 112 | /* FIXME: Can we really not continue? */ |
| 113 | rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n", |
| 114 | fd, strerror(errno)); |
| 115 | exit_cleanup(RERR_SOCKETIO); |
| 116 | } |
| 117 | |
| 118 | #ifdef INET6 |
| 119 | if (get_sockaddr_family(ss) == AF_INET6 && |
| 120 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { |
| 121 | /* OK, so ss is in the IPv6 family, but it is really |
| 122 | * an IPv4 address: something like |
| 123 | * "::ffff:10.130.1.2". If we use it as-is, then the |
| 124 | * reverse lookup might fail or perhaps something else |
| 125 | * bad might happen. So instead we convert it to an |
| 126 | * equivalent address in the IPv4 address family. */ |
| 127 | struct sockaddr_in6 sin6; |
| 128 | struct sockaddr_in *sin; |
| 129 | |
| 130 | memcpy(&sin6, ss, sizeof(sin6)); |
| 131 | sin = (struct sockaddr_in *)ss; |
| 132 | memset(sin, 0, sizeof(*sin)); |
| 133 | sin->sin_family = AF_INET; |
| 134 | *ss_len = sizeof(struct sockaddr_in); |
| 135 | #ifdef HAVE_SOCKADDR_LEN |
| 136 | sin->sin_len = *ss_len; |
| 137 | #endif |
| 138 | sin->sin_port = sin6.sin6_port; |
| 139 | |
| 140 | /* There is a macro to extract the mapped part |
| 141 | * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem |
| 142 | * to be present in the Linux headers. */ |
| 143 | memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], |
| 144 | sizeof(sin->sin_addr)); |
| 145 | } |
| 146 | #endif |
| 147 | } |
| 148 | |
| 149 | |
| 150 | /** |
| 151 | * Look up a name from @p ss into @p name_buf. |
| 152 | **/ |
| 153 | int lookup_name(int fd, const struct sockaddr_storage *ss, |
| 154 | socklen_t ss_len, |
| 155 | char *name_buf, size_t name_buf_len, |
| 156 | char *port_buf, size_t port_buf_len) |
| 157 | { |
| 158 | int name_err; |
| 159 | |
| 160 | /* reverse lookup */ |
| 161 | name_err = getnameinfo((struct sockaddr *) ss, ss_len, |
| 162 | name_buf, name_buf_len, |
| 163 | port_buf, port_buf_len, |
| 164 | NI_NAMEREQD | NI_NUMERICSERV); |
| 165 | if (name_err != 0) { |
| 166 | strcpy(name_buf, default_name); |
| 167 | rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n", |
| 168 | client_addr(fd), |
| 169 | gai_strerror(name_err)); |
| 170 | return name_err; |
| 171 | } |
| 172 | |
| 173 | return 0; |
| 174 | } |
| 175 | |
| 176 | |
| 177 | |
| 178 | /** |
| 179 | * Compare an addrinfo from the resolver to a sockinfo. |
| 180 | * |
| 181 | * Like strcmp, returns 0 for identical. |
| 182 | **/ |
| 183 | int compare_addrinfo_sockaddr(const struct addrinfo *ai, |
| 184 | const struct sockaddr_storage *ss) |
| 185 | { |
| 186 | int ss_family = get_sockaddr_family(ss); |
| 187 | const char fn[] = "compare_addrinfo_sockaddr"; |
| 188 | |
| 189 | if (ai->ai_family != ss_family) { |
| 190 | rprintf(FERROR, |
| 191 | "%s: response family %d != %d\n", |
| 192 | fn, ai->ai_family, ss_family); |
| 193 | return 1; |
| 194 | } |
| 195 | |
| 196 | /* The comparison method depends on the particular AF. */ |
| 197 | if (ss_family == AF_INET) { |
| 198 | const struct sockaddr_in *sin1, *sin2; |
| 199 | |
| 200 | sin1 = (const struct sockaddr_in *) ss; |
| 201 | sin2 = (const struct sockaddr_in *) ai->ai_addr; |
| 202 | |
| 203 | return memcmp(&sin1->sin_addr, &sin2->sin_addr, |
| 204 | sizeof sin1->sin_addr); |
| 205 | } |
| 206 | #ifdef INET6 |
| 207 | else if (ss_family == AF_INET6) { |
| 208 | const struct sockaddr_in6 *sin1, *sin2; |
| 209 | |
| 210 | sin1 = (const struct sockaddr_in6 *) ss; |
| 211 | sin2 = (const struct sockaddr_in6 *) ai->ai_addr; |
| 212 | |
| 213 | return memcmp(&sin1->sin6_addr, &sin2->sin6_addr, |
| 214 | sizeof sin1->sin6_addr); |
| 215 | } |
| 216 | #endif /* INET6 */ |
| 217 | else { |
| 218 | /* don't know */ |
| 219 | return 1; |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | |
| 224 | /** |
| 225 | * Do a forward lookup on @p name_buf and make sure it corresponds to |
| 226 | * @p ss -- otherwise we may be being spoofed. If we suspect we are, |
| 227 | * then we don't abort the connection but just emit a warning, and |
| 228 | * change @p name_buf to be "UNKNOWN". |
| 229 | **/ |
| 230 | int check_name(int fd, |
| 231 | const struct sockaddr_storage *ss, |
| 232 | char *name_buf, |
| 233 | const char *port_buf) |
| 234 | { |
| 235 | struct addrinfo hints, *res, *res0; |
| 236 | int error; |
| 237 | int ss_family = get_sockaddr_family(ss); |
| 238 | |
| 239 | memset(&hints, 0, sizeof(hints)); |
| 240 | hints.ai_family = ss_family; |
| 241 | hints.ai_flags = AI_CANONNAME; |
| 242 | hints.ai_socktype = SOCK_STREAM; |
| 243 | error = getaddrinfo(name_buf, port_buf, &hints, &res0); |
| 244 | if (error) { |
| 245 | rprintf(FERROR, |
| 246 | RSYNC_NAME ": forward name lookup for %s failed: %s\n", |
| 247 | name_buf, gai_strerror(error)); |
| 248 | strcpy(name_buf, default_name); |
| 249 | return error; |
| 250 | } |
| 251 | |
| 252 | |
| 253 | /* Given all these results, we expect that one of them will be |
| 254 | * the same as ss. The comparison is a bit complicated. */ |
| 255 | for (res = res0; res; res = res->ai_next) { |
| 256 | if (!compare_addrinfo_sockaddr(res, ss)) |
| 257 | break; /* OK, identical */ |
| 258 | } |
| 259 | |
| 260 | if (!res0) { |
| 261 | /* We hit the end of the list without finding an |
| 262 | * address that was the same as ss. */ |
| 263 | rprintf(FERROR, RSYNC_NAME |
| 264 | ": no known address for \"%s\": " |
| 265 | "spoofed address?\n", |
| 266 | name_buf); |
| 267 | strcpy(name_buf, default_name); |
| 268 | } else if (res == NULL) { |
| 269 | /* We hit the end of the list without finding an |
| 270 | * address that was the same as ss. */ |
| 271 | rprintf(FERROR, RSYNC_NAME |
| 272 | ": %s is not a known address for \"%s\": " |
| 273 | "spoofed address?\n", |
| 274 | client_addr(fd), |
| 275 | name_buf); |
| 276 | strcpy(name_buf, default_name); |
| 277 | } |
| 278 | |
| 279 | freeaddrinfo(res0); |
| 280 | return 0; |
| 281 | } |
| 282 | |