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3c0ef626 | 1 | /* |
2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
416fd2a8 | 26 | RCSID("$OpenBSD: auth2.c,v 1.104 2003/11/04 08:54:09 djm Exp $"); |
3c0ef626 | 27 | |
28 | #include "ssh2.h" | |
29 | #include "xmalloc.h" | |
3c0ef626 | 30 | #include "packet.h" |
3c0ef626 | 31 | #include "log.h" |
32 | #include "servconf.h" | |
416fd2a8 | 33 | #include "compat.h" |
3c0ef626 | 34 | #include "auth.h" |
3c0ef626 | 35 | #include "dispatch.h" |
3c0ef626 | 36 | #include "pathnames.h" |
2980ea68 | 37 | #include "monitor_wrap.h" |
3c0ef626 | 38 | |
5598e598 | 39 | #ifdef GSSAPI |
40 | #include "ssh-gss.h" | |
41 | #endif | |
42 | ||
3c0ef626 | 43 | /* import */ |
44 | extern ServerOptions options; | |
45 | extern u_char *session_id2; | |
70791e56 | 46 | extern u_int session_id2_len; |
3c0ef626 | 47 | |
ff2d7a98 | 48 | /* methods */ |
49 | ||
50 | extern Authmethod method_none; | |
ff2d7a98 | 51 | extern Authmethod method_pubkey; |
52 | extern Authmethod method_passwd; | |
53 | extern Authmethod method_kbdint; | |
54 | extern Authmethod method_hostbased; | |
88928908 | 55 | #ifdef GSSAPI |
56 | extern Authmethod method_external; | |
57 | extern Authmethod method_gssapi; | |
416fd2a8 | 58 | extern Authmethod method_gssapi_compat; |
88928908 | 59 | #endif |
ff2d7a98 | 60 | |
61 | Authmethod *authmethods[] = { | |
62 | &method_none, | |
ff2d7a98 | 63 | &method_pubkey, |
70791e56 | 64 | #ifdef GSSAPI |
416fd2a8 | 65 | &method_external, |
70791e56 | 66 | &method_gssapi, |
416fd2a8 | 67 | &method_gssapi_compat, |
70791e56 | 68 | #endif |
ff2d7a98 | 69 | &method_passwd, |
70 | &method_kbdint, | |
71 | &method_hostbased, | |
72 | NULL | |
3c0ef626 | 73 | }; |
74 | ||
75 | /* protocol */ | |
76 | ||
1e608e42 | 77 | static void input_service_request(int, u_int32_t, void *); |
78 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 79 | |
80 | /* helper */ | |
81 | static Authmethod *authmethod_lookup(const char *); | |
82 | static char *authmethods_get(void); | |
2980ea68 | 83 | int user_key_allowed(struct passwd *, Key *); |
3c0ef626 | 84 | |
3c0ef626 | 85 | /* |
86 | * loop until authctxt->success == TRUE | |
87 | */ | |
88 | ||
416fd2a8 | 89 | void |
90 | do_authentication2(Authctxt *authctxt) | |
3c0ef626 | 91 | { |
3c0ef626 | 92 | /* challenge-response is implemented via keyboard interactive */ |
93 | if (options.challenge_response_authentication) | |
94 | options.kbd_interactive_authentication = 1; | |
3c0ef626 | 95 | |
1e608e42 | 96 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 97 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
98 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
3c0ef626 | 99 | } |
100 | ||
101 | static void | |
1e608e42 | 102 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 103 | { |
104 | Authctxt *authctxt = ctxt; | |
105 | u_int len; | |
e54b3d7c | 106 | int acceptit = 0; |
3c0ef626 | 107 | char *service = packet_get_string(&len); |
1e608e42 | 108 | packet_check_eom(); |
3c0ef626 | 109 | |
110 | if (authctxt == NULL) | |
111 | fatal("input_service_request: no authctxt"); | |
112 | ||
113 | if (strcmp(service, "ssh-userauth") == 0) { | |
114 | if (!authctxt->success) { | |
e54b3d7c | 115 | acceptit = 1; |
3c0ef626 | 116 | /* now we can handle user-auth requests */ |
117 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
118 | } | |
119 | } | |
120 | /* XXX all other service requests are denied */ | |
121 | ||
e54b3d7c | 122 | if (acceptit) { |
3c0ef626 | 123 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
124 | packet_put_cstring(service); | |
125 | packet_send(); | |
126 | packet_write_wait(); | |
127 | } else { | |
128 | debug("bad service request %s", service); | |
129 | packet_disconnect("bad service request %s", service); | |
130 | } | |
131 | xfree(service); | |
132 | } | |
133 | ||
134 | static void | |
1e608e42 | 135 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 136 | { |
137 | Authctxt *authctxt = ctxt; | |
138 | Authmethod *m = NULL; | |
139 | char *user, *service, *method, *style = NULL; | |
140 | int authenticated = 0; | |
141 | ||
142 | if (authctxt == NULL) | |
143 | fatal("input_userauth_request: no authctxt"); | |
144 | ||
145 | user = packet_get_string(NULL); | |
146 | service = packet_get_string(NULL); | |
147 | method = packet_get_string(NULL); | |
2980ea68 | 148 | |
149 | #ifdef GSSAPI | |
ff2d7a98 | 150 | if (strcmp(user, "") == 0) { |
c2397a66 | 151 | debug("received empty username for %s", method); |
152 | if (strcmp(method, "external-keyx") == 0) { | |
153 | char *lname = NULL; | |
154 | PRIVSEP(ssh_gssapi_localname(&lname)); | |
155 | if (lname && lname[0] != '\0') { | |
156 | xfree(user); | |
157 | user = lname; | |
158 | debug("set username to %s from gssapi context", user); | |
159 | } else if (authctxt->valid) { | |
160 | debug("failed to set username from gssapi context"); | |
161 | } | |
ff2d7a98 | 162 | } |
163 | } | |
164 | #endif | |
2980ea68 | 165 | |
c2397a66 | 166 | debug("userauth-request for user %s service %s method %s", |
167 | (user && user[0]) ? user : "<implicit>", service, method); | |
3c0ef626 | 168 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); |
169 | ||
170 | if ((style = strchr(user, ':')) != NULL) | |
171 | *style++ = 0; | |
172 | ||
416fd2a8 | 173 | ; |
174 | /* If first time or username changed or implicit username, | |
175 | setup/reset authentication context. */ | |
176 | if ((authctxt->attempt++ == 0) || | |
177 | (strcmp(user, authctxt->user) != 0) || | |
178 | (strcmp(user, "") == 0)) { | |
3c0ef626 | 179 | /* setup auth context */ |
ff2d7a98 | 180 | if (authctxt->user) { |
181 | xfree(authctxt->user); | |
182 | authctxt->user = NULL; | |
183 | } | |
184 | if (authctxt->service) { | |
185 | xfree(authctxt->service); | |
186 | authctxt->service = NULL; | |
187 | } | |
188 | if (authctxt->style) { | |
189 | xfree(authctxt->style); | |
190 | authctxt->style = NULL; | |
191 | } | |
c2397a66 | 192 | #ifdef GSSAPI |
193 | /* We'll verify the username after we set it from the | |
194 | GSSAPI context. */ | |
195 | if ((strcmp(user, "") == 0) && | |
196 | ((strcmp(method, "gssapi") == 0) || | |
197 | (strcmp(method, "external-keyx") == 0))) { | |
198 | authctxt->pw = NULL; | |
199 | authctxt->valid = 1; | |
200 | } else { | |
201 | #endif | |
2980ea68 | 202 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
203 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { | |
3c0ef626 | 204 | authctxt->valid = 1; |
205 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
206 | #ifdef USE_PAM | |
70791e56 | 207 | if (options.use_pam) |
208 | PRIVSEP(start_pam(authctxt->pw->pw_name)); | |
3c0ef626 | 209 | #endif |
210 | } else { | |
70791e56 | 211 | logit("input_userauth_request: illegal user %s", user); |
212 | authctxt->pw = fakepw(); | |
3c0ef626 | 213 | #ifdef USE_PAM |
70791e56 | 214 | if (options.use_pam) |
215 | PRIVSEP(start_pam(user)); | |
3c0ef626 | 216 | #endif |
217 | } | |
c2397a66 | 218 | #ifdef GSSAPI |
219 | } | |
220 | #endif | |
2980ea68 | 221 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
222 | use_privsep ? " [net]" : ""); | |
3c0ef626 | 223 | authctxt->user = xstrdup(user); |
224 | authctxt->service = xstrdup(service); | |
225 | authctxt->style = style ? xstrdup(style) : NULL; | |
c2397a66 | 226 | if (use_privsep && (authctxt->attempt == 1)) |
2980ea68 | 227 | mm_inform_authserv(service, style); |
88928908 | 228 | } else if (strcmp(service, authctxt->service) != 0) { |
229 | packet_disconnect("Change of service not allowed: " | |
230 | "(%s,%s) -> (%s,%s)", | |
231 | authctxt->user, authctxt->service, user, service); | |
3c0ef626 | 232 | } |
233 | /* reset state */ | |
1e608e42 | 234 | auth2_challenge_stop(authctxt); |
5598e598 | 235 | |
236 | #ifdef GSSAPI | |
1e608e42 | 237 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
238 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
5598e598 | 239 | #endif |
240 | ||
3c0ef626 | 241 | authctxt->postponed = 0; |
3c0ef626 | 242 | |
243 | /* try to authenticate user */ | |
244 | m = authmethod_lookup(method); | |
245 | if (m != NULL) { | |
246 | debug2("input_userauth_request: try method %s", method); | |
247 | authenticated = m->userauth(authctxt); | |
248 | } | |
249 | userauth_finish(authctxt, authenticated, method); | |
250 | ||
251 | xfree(service); | |
252 | xfree(user); | |
253 | xfree(method); | |
254 | } | |
255 | ||
256 | void | |
257 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
258 | { | |
259 | char *methods; | |
260 | ||
261 | if (!authctxt->valid && authenticated) | |
262 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
263 | authctxt->user); | |
264 | ||
265 | /* Special handling for root */ | |
1c14df9e | 266 | if (authenticated && authctxt->pw->pw_uid == 0 && |
3c0ef626 | 267 | !auth_root_allowed(method)) |
268 | authenticated = 0; | |
269 | ||
270 | #ifdef USE_PAM | |
70791e56 | 271 | if (options.use_pam && authenticated && !PRIVSEP(do_pam_account())) |
3c0ef626 | 272 | authenticated = 0; |
70791e56 | 273 | #endif |
3c0ef626 | 274 | |
e54b3d7c | 275 | #ifdef _UNICOS |
276 | if (authenticated && cray_access_denied(authctxt->user)) { | |
277 | authenticated = 0; | |
278 | fatal("Access denied for user %s.",authctxt->user); | |
279 | } | |
280 | #endif /* _UNICOS */ | |
281 | ||
3c0ef626 | 282 | /* Log before sending the reply */ |
283 | auth_log(authctxt, authenticated, method, " ssh2"); | |
284 | ||
285 | if (authctxt->postponed) | |
286 | return; | |
287 | ||
288 | /* XXX todo: check if multiple auth methods are needed */ | |
289 | if (authenticated == 1) { | |
290 | /* turn off userauth */ | |
1e608e42 | 291 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 292 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
293 | packet_send(); | |
294 | packet_write_wait(); | |
295 | /* now we can break out */ | |
296 | authctxt->success = 1; | |
297 | } else { | |
70791e56 | 298 | if (authctxt->failures++ > AUTH_FAIL_MAX) |
3c0ef626 | 299 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
3c0ef626 | 300 | methods = authmethods_get(); |
301 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
302 | packet_put_cstring(methods); | |
303 | packet_put_char(0); /* XXX partial success, unused */ | |
304 | packet_send(); | |
305 | packet_write_wait(); | |
306 | xfree(methods); | |
307 | } | |
308 | } | |
309 | ||
3c0ef626 | 310 | #define DELIM "," |
311 | ||
312 | static char * | |
313 | authmethods_get(void) | |
314 | { | |
1e608e42 | 315 | Buffer b; |
3c0ef626 | 316 | char *list; |
ff2d7a98 | 317 | int i; |
3c0ef626 | 318 | |
1e608e42 | 319 | buffer_init(&b); |
ff2d7a98 | 320 | for (i = 0; authmethods[i] != NULL; i++) { |
321 | if (strcmp(authmethods[i]->name, "none") == 0) | |
3c0ef626 | 322 | continue; |
ff2d7a98 | 323 | if (authmethods[i]->enabled != NULL && |
324 | *(authmethods[i]->enabled) != 0) { | |
1e608e42 | 325 | if (buffer_len(&b) > 0) |
326 | buffer_append(&b, ",", 1); | |
ff2d7a98 | 327 | buffer_append(&b, authmethods[i]->name, |
328 | strlen(authmethods[i]->name)); | |
3c0ef626 | 329 | } |
330 | } | |
1e608e42 | 331 | buffer_append(&b, "\0", 1); |
332 | list = xstrdup(buffer_ptr(&b)); | |
333 | buffer_free(&b); | |
3c0ef626 | 334 | return list; |
335 | } | |
336 | ||
337 | static Authmethod * | |
338 | authmethod_lookup(const char *name) | |
339 | { | |
ff2d7a98 | 340 | int i; |
341 | ||
3c0ef626 | 342 | if (name != NULL) |
ff2d7a98 | 343 | for (i = 0; authmethods[i] != NULL; i++) |
344 | if (authmethods[i]->enabled != NULL && | |
345 | *(authmethods[i]->enabled) != 0 && | |
346 | strcmp(name, authmethods[i]->name) == 0) | |
347 | return authmethods[i]; | |
348 | debug2("Unrecognized authentication method name: %s", | |
349 | name ? name : "NULL"); | |
3c0ef626 | 350 | return NULL; |
351 | } |