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a0d38609 | 1 | /* $OpenBSD: auth2.c,v 1.118 2008/07/02 13:30:34 djm Exp $ */ |
a306f2dd | 2 | /* |
3 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
a306f2dd | 13 | * |
14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
24 | */ | |
bcbf86ec | 25 | |
a306f2dd | 26 | #include "includes.h" |
a306f2dd | 27 | |
b1842393 | 28 | #include <sys/types.h> |
221fc73c | 29 | #include <sys/stat.h> |
30 | #include <sys/uio.h> | |
b1842393 | 31 | |
221fc73c | 32 | #include <fcntl.h> |
b1842393 | 33 | #include <pwd.h> |
31652869 | 34 | #include <stdarg.h> |
00146caa | 35 | #include <string.h> |
221fc73c | 36 | #include <unistd.h> |
b1842393 | 37 | |
a306f2dd | 38 | #include "xmalloc.h" |
31652869 | 39 | #include "ssh2.h" |
a306f2dd | 40 | #include "packet.h" |
42f11eb2 | 41 | #include "log.h" |
31652869 | 42 | #include "buffer.h" |
a306f2dd | 43 | #include "servconf.h" |
44 | #include "compat.h" | |
31652869 | 45 | #include "key.h" |
46 | #include "hostfile.h" | |
a306f2dd | 47 | #include "auth.h" |
a306f2dd | 48 | #include "dispatch.h" |
42f11eb2 | 49 | #include "pathnames.h" |
ba6dd90e | 50 | #include "buffer.h" |
a306f2dd | 51 | |
7364bd04 | 52 | #ifdef GSSAPI |
53 | #include "ssh-gss.h" | |
54 | #endif | |
31652869 | 55 | #include "monitor_wrap.h" |
7364bd04 | 56 | |
a306f2dd | 57 | /* import */ |
58 | extern ServerOptions options; | |
1e3b8b07 | 59 | extern u_char *session_id2; |
a27002e5 | 60 | extern u_int session_id2_len; |
ba6dd90e | 61 | extern Buffer loginmsg; |
a306f2dd | 62 | |
01c24737 | 63 | /* methods */ |
64 | ||
65 | extern Authmethod method_none; | |
66 | extern Authmethod method_pubkey; | |
67 | extern Authmethod method_passwd; | |
68 | extern Authmethod method_kbdint; | |
69 | extern Authmethod method_hostbased; | |
7364bd04 | 70 | #ifdef GSSAPI |
71 | extern Authmethod method_gssapi; | |
72 | #endif | |
01c24737 | 73 | |
74 | Authmethod *authmethods[] = { | |
75 | &method_none, | |
76 | &method_pubkey, | |
7364bd04 | 77 | #ifdef GSSAPI |
78 | &method_gssapi, | |
79 | #endif | |
01c24737 | 80 | &method_passwd, |
81 | &method_kbdint, | |
82 | &method_hostbased, | |
83 | NULL | |
94ec8c6b | 84 | }; |
85 | ||
a306f2dd | 86 | /* protocol */ |
87 | ||
7819b5c3 | 88 | static void input_service_request(int, u_int32_t, void *); |
89 | static void input_userauth_request(int, u_int32_t, void *); | |
a306f2dd | 90 | |
a306f2dd | 91 | /* helper */ |
396c147e | 92 | static Authmethod *authmethod_lookup(const char *); |
ffb215be | 93 | static char *authmethods_get(void); |
a306f2dd | 94 | |
221fc73c | 95 | char * |
96 | auth2_read_banner(void) | |
97 | { | |
98 | struct stat st; | |
99 | char *banner = NULL; | |
100 | size_t len, n; | |
101 | int fd; | |
102 | ||
103 | if ((fd = open(options.banner, O_RDONLY)) == -1) | |
104 | return (NULL); | |
105 | if (fstat(fd, &st) == -1) { | |
106 | close(fd); | |
107 | return (NULL); | |
108 | } | |
109 | if (st.st_size > 1*1024*1024) { | |
110 | close(fd); | |
111 | return (NULL); | |
112 | } | |
113 | ||
114 | len = (size_t)st.st_size; /* truncate */ | |
115 | banner = xmalloc(len + 1); | |
116 | n = atomicio(read, fd, banner, len); | |
117 | close(fd); | |
118 | ||
119 | if (n != len) { | |
120 | xfree(banner); | |
121 | return (NULL); | |
122 | } | |
123 | banner[n] = '\0'; | |
124 | ||
125 | return (banner); | |
126 | } | |
127 | ||
128 | void | |
129 | userauth_send_banner(const char *msg) | |
130 | { | |
131 | if (datafellows & SSH_BUG_BANNER) | |
132 | return; | |
133 | ||
134 | packet_start(SSH2_MSG_USERAUTH_BANNER); | |
135 | packet_put_cstring(msg); | |
136 | packet_put_cstring(""); /* language, unused */ | |
137 | packet_send(); | |
138 | debug("%s: sent", __func__); | |
139 | } | |
140 | ||
141 | static void | |
142 | userauth_banner(void) | |
143 | { | |
144 | char *banner = NULL; | |
145 | ||
146 | if (options.banner == NULL || | |
147 | strcasecmp(options.banner, "none") == 0 || | |
148 | (datafellows & SSH_BUG_BANNER) != 0) | |
149 | return; | |
150 | ||
151 | if ((banner = PRIVSEP(auth2_read_banner())) == NULL) | |
152 | goto done; | |
153 | userauth_send_banner(banner); | |
154 | ||
155 | done: | |
156 | if (banner) | |
157 | xfree(banner); | |
158 | } | |
159 | ||
a306f2dd | 160 | /* |
94ec8c6b | 161 | * loop until authctxt->success == TRUE |
a306f2dd | 162 | */ |
2362db19 | 163 | void |
164 | do_authentication2(Authctxt *authctxt) | |
a306f2dd | 165 | { |
6367063f | 166 | dispatch_init(&dispatch_protocol_error); |
a306f2dd | 167 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
94ec8c6b | 168 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); |
a306f2dd | 169 | } |
170 | ||
fe8c3af1 | 171 | /*ARGSUSED*/ |
396c147e | 172 | static void |
7819b5c3 | 173 | input_service_request(int type, u_int32_t seq, void *ctxt) |
a306f2dd | 174 | { |
94ec8c6b | 175 | Authctxt *authctxt = ctxt; |
1e3b8b07 | 176 | u_int len; |
7fdc56c5 | 177 | int acceptit = 0; |
a306f2dd | 178 | char *service = packet_get_string(&len); |
95500969 | 179 | packet_check_eom(); |
a306f2dd | 180 | |
94ec8c6b | 181 | if (authctxt == NULL) |
182 | fatal("input_service_request: no authctxt"); | |
183 | ||
a306f2dd | 184 | if (strcmp(service, "ssh-userauth") == 0) { |
94ec8c6b | 185 | if (!authctxt->success) { |
7fdc56c5 | 186 | acceptit = 1; |
a306f2dd | 187 | /* now we can handle user-auth requests */ |
188 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
189 | } | |
190 | } | |
191 | /* XXX all other service requests are denied */ | |
192 | ||
7fdc56c5 | 193 | if (acceptit) { |
a306f2dd | 194 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
195 | packet_put_cstring(service); | |
196 | packet_send(); | |
197 | packet_write_wait(); | |
198 | } else { | |
199 | debug("bad service request %s", service); | |
200 | packet_disconnect("bad service request %s", service); | |
201 | } | |
202 | xfree(service); | |
203 | } | |
204 | ||
fe8c3af1 | 205 | /*ARGSUSED*/ |
396c147e | 206 | static void |
7819b5c3 | 207 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
a306f2dd | 208 | { |
94ec8c6b | 209 | Authctxt *authctxt = ctxt; |
210 | Authmethod *m = NULL; | |
59c97189 | 211 | char *user, *service, *method, *style = NULL; |
a306f2dd | 212 | int authenticated = 0; |
a306f2dd | 213 | |
94ec8c6b | 214 | if (authctxt == NULL) |
215 | fatal("input_userauth_request: no authctxt"); | |
a306f2dd | 216 | |
94ec8c6b | 217 | user = packet_get_string(NULL); |
218 | service = packet_get_string(NULL); | |
219 | method = packet_get_string(NULL); | |
220 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
8abcdba4 | 221 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); |
94ec8c6b | 222 | |
59c97189 | 223 | if ((style = strchr(user, ':')) != NULL) |
224 | *style++ = 0; | |
225 | ||
2b87da3b | 226 | if (authctxt->attempt++ == 0) { |
63284fbb | 227 | /* setup auth context */ |
f7ed12f1 | 228 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
529d73ab | 229 | authctxt->user = xstrdup(user); |
f7ed12f1 | 230 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { |
94ec8c6b | 231 | authctxt->valid = 1; |
232 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
94ec8c6b | 233 | } else { |
d77347cc | 234 | logit("input_userauth_request: invalid user %s", user); |
96d0bf74 | 235 | authctxt->pw = fakepw(); |
6039eeef | 236 | #ifdef SSH_AUDIT_EVENTS |
237 | PRIVSEP(audit_event(SSH_INVALID_USER)); | |
04fc7a67 | 238 | #endif |
94ec8c6b | 239 | } |
b6c37221 | 240 | #ifdef USE_PAM |
241 | if (options.use_pam) | |
242 | PRIVSEP(start_pam(authctxt)); | |
243 | #endif | |
bd5c0694 | 244 | setproctitle("%s%s", authctxt->valid ? user : "unknown", |
1853d1ef | 245 | use_privsep ? " [net]" : ""); |
94ec8c6b | 246 | authctxt->service = xstrdup(service); |
2a6a054e | 247 | authctxt->style = style ? xstrdup(style) : NULL; |
1853d1ef | 248 | if (use_privsep) |
249 | mm_inform_authserv(service, style); | |
221fc73c | 250 | userauth_banner(); |
2a6a054e | 251 | } else if (strcmp(user, authctxt->user) != 0 || |
252 | strcmp(service, authctxt->service) != 0) { | |
253 | packet_disconnect("Change of username or service not allowed: " | |
254 | "(%s,%s) -> (%s,%s)", | |
255 | authctxt->user, authctxt->service, user, service); | |
a306f2dd | 256 | } |
59c97189 | 257 | /* reset state */ |
2f293d43 | 258 | auth2_challenge_stop(authctxt); |
7364bd04 | 259 | |
260 | #ifdef GSSAPI | |
261 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
262 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
263 | #endif | |
264 | ||
59c97189 | 265 | authctxt->postponed = 0; |
9cd45ea4 | 266 | |
59c97189 | 267 | /* try to authenticate user */ |
94ec8c6b | 268 | m = authmethod_lookup(method); |
221fc73c | 269 | if (m != NULL && authctxt->failures < options.max_authtries) { |
94ec8c6b | 270 | debug2("input_userauth_request: try method %s", method); |
271 | authenticated = m->userauth(authctxt); | |
9cd45ea4 | 272 | } |
d9cd3575 | 273 | userauth_finish(authctxt, authenticated, method); |
274 | ||
275 | xfree(service); | |
276 | xfree(user); | |
277 | xfree(method); | |
278 | } | |
279 | ||
280 | void | |
281 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
282 | { | |
4e81159c | 283 | char *methods; |
284 | ||
59c97189 | 285 | if (!authctxt->valid && authenticated) |
286 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
287 | authctxt->user); | |
9cd45ea4 | 288 | |
94ec8c6b | 289 | /* Special handling for root */ |
5d47f1d4 | 290 | if (authenticated && authctxt->pw->pw_uid == 0 && |
c00e4d75 | 291 | !auth_root_allowed(method)) { |
a306f2dd | 292 | authenticated = 0; |
6039eeef | 293 | #ifdef SSH_AUDIT_EVENTS |
294 | PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); | |
c00e4d75 | 295 | #endif |
296 | } | |
a306f2dd | 297 | |
5b9e2464 | 298 | #ifdef USE_PAM |
ba6dd90e | 299 | if (options.use_pam && authenticated) { |
300 | if (!PRIVSEP(do_pam_account())) { | |
ba6dd90e | 301 | /* if PAM returned a message, send it to the user */ |
302 | if (buffer_len(&loginmsg) > 0) { | |
303 | buffer_append(&loginmsg, "\0", 1); | |
304 | userauth_send_banner(buffer_ptr(&loginmsg)); | |
9aab0af7 | 305 | packet_write_wait(); |
ba6dd90e | 306 | } |
9aab0af7 | 307 | fatal("Access denied for user %s by PAM account " |
98c044d0 | 308 | "configuration", authctxt->user); |
ba6dd90e | 309 | } |
310 | } | |
5b9e2464 | 311 | #endif |
312 | ||
ef51930f | 313 | #ifdef _UNICOS |
314 | if (authenticated && cray_access_denied(authctxt->user)) { | |
315 | authenticated = 0; | |
316 | fatal("Access denied for user %s.",authctxt->user); | |
317 | } | |
318 | #endif /* _UNICOS */ | |
319 | ||
94ec8c6b | 320 | /* Log before sending the reply */ |
59c97189 | 321 | auth_log(authctxt, authenticated, method, " ssh2"); |
322 | ||
4e81159c | 323 | if (authctxt->postponed) |
324 | return; | |
325 | ||
326 | /* XXX todo: check if multiple auth methods are needed */ | |
327 | if (authenticated == 1) { | |
328 | /* turn off userauth */ | |
6367063f | 329 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
4e81159c | 330 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
331 | packet_send(); | |
332 | packet_write_wait(); | |
333 | /* now we can break out */ | |
334 | authctxt->success = 1; | |
335 | } else { | |
a0d38609 | 336 | if (++authctxt->failures >= options.max_authtries) { |
6039eeef | 337 | #ifdef SSH_AUDIT_EVENTS |
338 | PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); | |
c00e4d75 | 339 | #endif |
4e81159c | 340 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
c00e4d75 | 341 | } |
4e81159c | 342 | methods = authmethods_get(); |
343 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
344 | packet_put_cstring(methods); | |
345 | packet_put_char(0); /* XXX partial success, unused */ | |
346 | packet_send(); | |
347 | packet_write_wait(); | |
348 | xfree(methods); | |
349 | } | |
94ec8c6b | 350 | } |
351 | ||
ffb215be | 352 | static char * |
94ec8c6b | 353 | authmethods_get(void) |
a306f2dd | 354 | { |
3469eac4 | 355 | Buffer b; |
94ec8c6b | 356 | char *list; |
01c24737 | 357 | int i; |
94ec8c6b | 358 | |
3469eac4 | 359 | buffer_init(&b); |
01c24737 | 360 | for (i = 0; authmethods[i] != NULL; i++) { |
361 | if (strcmp(authmethods[i]->name, "none") == 0) | |
94ec8c6b | 362 | continue; |
01c24737 | 363 | if (authmethods[i]->enabled != NULL && |
364 | *(authmethods[i]->enabled) != 0) { | |
3469eac4 | 365 | if (buffer_len(&b) > 0) |
366 | buffer_append(&b, ",", 1); | |
01c24737 | 367 | buffer_append(&b, authmethods[i]->name, |
368 | strlen(authmethods[i]->name)); | |
a306f2dd | 369 | } |
370 | } | |
3469eac4 | 371 | buffer_append(&b, "\0", 1); |
372 | list = xstrdup(buffer_ptr(&b)); | |
373 | buffer_free(&b); | |
94ec8c6b | 374 | return list; |
375 | } | |
376 | ||
396c147e | 377 | static Authmethod * |
94ec8c6b | 378 | authmethod_lookup(const char *name) |
379 | { | |
01c24737 | 380 | int i; |
381 | ||
94ec8c6b | 382 | if (name != NULL) |
01c24737 | 383 | for (i = 0; authmethods[i] != NULL; i++) |
384 | if (authmethods[i]->enabled != NULL && | |
385 | *(authmethods[i]->enabled) != 0 && | |
386 | strcmp(name, authmethods[i]->name) == 0) | |
387 | return authmethods[i]; | |
388 | debug2("Unrecognized authentication method name: %s", | |
389 | name ? name : "NULL"); | |
94ec8c6b | 390 | return NULL; |
a306f2dd | 391 | } |
221fc73c | 392 |