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0cd2f407 MP |
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; | |
09021eab | 46 | char *ssh_client, *p; |
0cd2f407 MP |
47 | static char addr_buf[100]; |
48 | static int initialised; | |
49 | ||
50 | if (initialised) return addr_buf; | |
51 | ||
52 | initialised = 1; | |
53 | ||
09021eab DD |
54 | ssh_client = getenv("SSH_CLIENT"); |
55 | if (ssh_client != NULL) { | |
56 | strlcpy(addr_buf, ssh_client, sizeof(addr_buf)); | |
57 | /* truncate SSH_CLIENT to just IP address */ | |
58 | p = strchr(addr_buf, ' '); | |
59 | if (p) | |
60 | *p = '\0'; | |
61 | else | |
62 | strlcpy(addr_buf, "0.0.0.0", sizeof("0.0.0.0")); | |
63 | } else | |
64 | client_sockaddr(fd, &ss, &length); | |
0cd2f407 MP |
65 | |
66 | getnameinfo((struct sockaddr *)&ss, length, | |
09021eab DD |
67 | addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST); |
68 | ||
0cd2f407 MP |
69 | return addr_buf; |
70 | } | |
71 | ||
72 | ||
73 | static int get_sockaddr_family(const struct sockaddr_storage *ss) | |
74 | { | |
75 | return ((struct sockaddr *) ss)->sa_family; | |
76 | } | |
77 | ||
78 | ||
79 | /** | |
80 | * Return the DNS name of the client. | |
81 | * | |
82 | * The name is statically cached so that repeated lookups are quick, | |
83 | * so there is a limit of one lookup per customer. | |
84 | * | |
85 | * If anything goes wrong, including the name->addr->name check, then | |
86 | * we just use "UNKNOWN", so you can use that value in hosts allow | |
87 | * lines. | |
6c92af20 MP |
88 | * |
89 | * After translation from sockaddr to name we do a forward lookup to | |
90 | * make sure nobody is spoofing PTR records. | |
0cd2f407 MP |
91 | **/ |
92 | char *client_name(int fd) | |
93 | { | |
0cd2f407 MP |
94 | static char name_buf[100]; |
95 | static char port_buf[100]; | |
96 | static int initialised; | |
97 | ||
98 | if (initialised) return name_buf; | |
99 | ||
100 | strcpy(name_buf, default_name); | |
101 | initialised = 1; | |
102 | ||
09021eab DD |
103 | if (getenv("SSH_CLIENT") != NULL) { |
104 | /* Look up name of IP address given in $SSH_CLIENT */ | |
105 | #ifdef INET6 | |
106 | int af = AF_INET6; | |
107 | struct sockaddr_in6 sin; | |
108 | #else | |
109 | int af = AF_INET; | |
110 | struct sockaddr_in sin; | |
111 | #endif | |
112 | socklen_t sin_len = sizeof sin; | |
113 | ||
114 | memset(&sin, 0, sin_len); | |
115 | sin.sin_family = af; | |
116 | inet_pton(af, client_addr(fd), &sin.sin_addr.s_addr); | |
117 | ||
118 | if (!lookup_name(fd, (struct sockaddr_storage *)&sin, sin_len, | |
119 | name_buf, sizeof name_buf, port_buf, sizeof port_buf)) | |
120 | check_name(fd, (struct sockaddr_storage *)&sin, name_buf); | |
121 | } else { | |
122 | struct sockaddr_storage ss; | |
123 | socklen_t ss_len = sizeof ss; | |
124 | ||
125 | client_sockaddr(fd, &ss, &ss_len); | |
126 | ||
127 | if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, | |
128 | port_buf, sizeof port_buf)) | |
129 | check_name(fd, &ss, name_buf); | |
130 | } | |
0cd2f407 MP |
131 | |
132 | return name_buf; | |
133 | } | |
134 | ||
135 | ||
136 | ||
137 | /** | |
af32f69e MP |
138 | * Get the sockaddr for the client. |
139 | * | |
140 | * If it comes in as an ipv4 address mapped into IPv6 format then we | |
141 | * convert it back to a regular IPv4. | |
0cd2f407 MP |
142 | **/ |
143 | void client_sockaddr(int fd, | |
144 | struct sockaddr_storage *ss, | |
145 | socklen_t *ss_len) | |
146 | { | |
147 | if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { | |
148 | /* FIXME: Can we really not continue? */ | |
149 | rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n", | |
150 | fd, strerror(errno)); | |
151 | exit_cleanup(RERR_SOCKETIO); | |
152 | } | |
153 | ||
154 | #ifdef INET6 | |
155 | if (get_sockaddr_family(ss) == AF_INET6 && | |
156 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { | |
157 | /* OK, so ss is in the IPv6 family, but it is really | |
158 | * an IPv4 address: something like | |
159 | * "::ffff:10.130.1.2". If we use it as-is, then the | |
160 | * reverse lookup might fail or perhaps something else | |
161 | * bad might happen. So instead we convert it to an | |
162 | * equivalent address in the IPv4 address family. */ | |
163 | struct sockaddr_in6 sin6; | |
164 | struct sockaddr_in *sin; | |
165 | ||
166 | memcpy(&sin6, ss, sizeof(sin6)); | |
167 | sin = (struct sockaddr_in *)ss; | |
168 | memset(sin, 0, sizeof(*sin)); | |
169 | sin->sin_family = AF_INET; | |
170 | *ss_len = sizeof(struct sockaddr_in); | |
171 | #ifdef HAVE_SOCKADDR_LEN | |
172 | sin->sin_len = *ss_len; | |
173 | #endif | |
174 | sin->sin_port = sin6.sin6_port; | |
175 | ||
176 | /* There is a macro to extract the mapped part | |
177 | * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem | |
178 | * to be present in the Linux headers. */ | |
179 | memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], | |
180 | sizeof(sin->sin_addr)); | |
181 | } | |
182 | #endif | |
183 | } | |
184 | ||
185 | ||
186 | /** | |
187 | * Look up a name from @p ss into @p name_buf. | |
6c92af20 MP |
188 | * |
189 | * @param fd file descriptor for client socket. | |
0cd2f407 MP |
190 | **/ |
191 | int lookup_name(int fd, const struct sockaddr_storage *ss, | |
192 | socklen_t ss_len, | |
193 | char *name_buf, size_t name_buf_len, | |
194 | char *port_buf, size_t port_buf_len) | |
195 | { | |
196 | int name_err; | |
197 | ||
198 | /* reverse lookup */ | |
199 | name_err = getnameinfo((struct sockaddr *) ss, ss_len, | |
200 | name_buf, name_buf_len, | |
201 | port_buf, port_buf_len, | |
202 | NI_NAMEREQD | NI_NUMERICSERV); | |
203 | if (name_err != 0) { | |
204 | strcpy(name_buf, default_name); | |
205 | rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n", | |
206 | client_addr(fd), | |
207 | gai_strerror(name_err)); | |
208 | return name_err; | |
209 | } | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
214 | ||
215 | ||
974f27e7 MP |
216 | /** |
217 | * Compare an addrinfo from the resolver to a sockinfo. | |
218 | * | |
219 | * Like strcmp, returns 0 for identical. | |
220 | **/ | |
221 | int compare_addrinfo_sockaddr(const struct addrinfo *ai, | |
222 | const struct sockaddr_storage *ss) | |
223 | { | |
224 | int ss_family = get_sockaddr_family(ss); | |
225 | const char fn[] = "compare_addrinfo_sockaddr"; | |
226 | ||
227 | if (ai->ai_family != ss_family) { | |
228 | rprintf(FERROR, | |
229 | "%s: response family %d != %d\n", | |
230 | fn, ai->ai_family, ss_family); | |
231 | return 1; | |
232 | } | |
233 | ||
39e01d2d MP |
234 | /* The comparison method depends on the particular AF. */ |
235 | if (ss_family == AF_INET) { | |
236 | const struct sockaddr_in *sin1, *sin2; | |
237 | ||
238 | sin1 = (const struct sockaddr_in *) ss; | |
239 | sin2 = (const struct sockaddr_in *) ai->ai_addr; | |
240 | ||
6780f720 MP |
241 | return memcmp(&sin1->sin_addr, &sin2->sin_addr, |
242 | sizeof sin1->sin_addr); | |
39e01d2d | 243 | } |
974f27e7 | 244 | #ifdef INET6 |
39e01d2d | 245 | else if (ss_family == AF_INET6) { |
6780f720 MP |
246 | const struct sockaddr_in6 *sin1, *sin2; |
247 | ||
248 | sin1 = (const struct sockaddr_in6 *) ss; | |
249 | sin2 = (const struct sockaddr_in6 *) ai->ai_addr; | |
250 | ||
251 | return memcmp(&sin1->sin6_addr, &sin2->sin6_addr, | |
252 | sizeof sin1->sin6_addr); | |
39e01d2d MP |
253 | } |
254 | #endif /* INET6 */ | |
255 | else { | |
256 | /* don't know */ | |
974f27e7 MP |
257 | return 1; |
258 | } | |
259 | } | |
260 | ||
261 | ||
af32f69e MP |
262 | /** |
263 | * Do a forward lookup on @p name_buf and make sure it corresponds to | |
264 | * @p ss -- otherwise we may be being spoofed. If we suspect we are, | |
265 | * then we don't abort the connection but just emit a warning, and | |
266 | * change @p name_buf to be "UNKNOWN". | |
6c92af20 MP |
267 | * |
268 | * We don't do anything with the service when checking the name, | |
269 | * because it doesn't seem that it could be spoofed in any way, and | |
270 | * getaddrinfo on random service names seems to cause problems on AIX. | |
af32f69e | 271 | **/ |
0cd2f407 MP |
272 | int check_name(int fd, |
273 | const struct sockaddr_storage *ss, | |
6c92af20 | 274 | char *name_buf) |
0cd2f407 MP |
275 | { |
276 | struct addrinfo hints, *res, *res0; | |
277 | int error; | |
278 | int ss_family = get_sockaddr_family(ss); | |
279 | ||
280 | memset(&hints, 0, sizeof(hints)); | |
39e01d2d MP |
281 | hints.ai_family = ss_family; |
282 | hints.ai_flags = AI_CANONNAME; | |
0cd2f407 | 283 | hints.ai_socktype = SOCK_STREAM; |
6c92af20 | 284 | error = getaddrinfo(name_buf, NULL, &hints, &res0); |
0cd2f407 MP |
285 | if (error) { |
286 | rprintf(FERROR, | |
af32f69e MP |
287 | RSYNC_NAME ": forward name lookup for %s failed: %s\n", |
288 | name_buf, gai_strerror(error)); | |
0cd2f407 MP |
289 | strcpy(name_buf, default_name); |
290 | return error; | |
291 | } | |
292 | ||
293 | ||
974f27e7 MP |
294 | /* Given all these results, we expect that one of them will be |
295 | * the same as ss. The comparison is a bit complicated. */ | |
0cd2f407 | 296 | for (res = res0; res; res = res->ai_next) { |
974f27e7 MP |
297 | if (!compare_addrinfo_sockaddr(res, ss)) |
298 | break; /* OK, identical */ | |
0cd2f407 MP |
299 | } |
300 | ||
301 | if (!res0) { | |
302 | /* We hit the end of the list without finding an | |
303 | * address that was the same as ss. */ | |
304 | rprintf(FERROR, RSYNC_NAME | |
305 | ": no known address for \"%s\": " | |
306 | "spoofed address?\n", | |
307 | name_buf); | |
308 | strcpy(name_buf, default_name); | |
974f27e7 | 309 | } else if (res == NULL) { |
0cd2f407 MP |
310 | /* We hit the end of the list without finding an |
311 | * address that was the same as ss. */ | |
312 | rprintf(FERROR, RSYNC_NAME | |
313 | ": %s is not a known address for \"%s\": " | |
314 | "spoofed address?\n", | |
315 | client_addr(fd), | |
316 | name_buf); | |
317 | strcpy(name_buf, default_name); | |
318 | } | |
319 | ||
320 | freeaddrinfo(res0); | |
321 | return 0; | |
322 | } | |
323 |