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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" | |
9cb1827b | 26 | RCSID("$OpenBSD: auth2.c,v 1.102 2003/08/26 09:58:43 markus 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" | |
33 | #include "compat.h" | |
3c0ef626 | 34 | #include "auth.h" |
3c0ef626 | 35 | #include "dispatch.h" |
3c0ef626 | 36 | #include "pathnames.h" |
700318f3 | 37 | #include "monitor_wrap.h" |
3c0ef626 | 38 | |
0fff78ff | 39 | #ifdef GSSAPI |
40 | #include "ssh-gss.h" | |
41 | #endif | |
42 | ||
3c0ef626 | 43 | /* import */ |
44 | extern ServerOptions options; | |
45 | extern u_char *session_id2; | |
0fff78ff | 46 | extern u_int session_id2_len; |
3c0ef626 | 47 | |
9cb1827b | 48 | Authctxt *x_authctxt = NULL; |
49 | ||
f5799ae1 | 50 | /* methods */ |
51 | ||
52 | extern Authmethod method_none; | |
53 | extern Authmethod method_pubkey; | |
54 | extern Authmethod method_passwd; | |
55 | extern Authmethod method_kbdint; | |
56 | extern Authmethod method_hostbased; | |
0fff78ff | 57 | #ifdef GSSAPI |
58 | extern Authmethod method_gssapi; | |
59 | #endif | |
f5799ae1 | 60 | |
61 | Authmethod *authmethods[] = { | |
62 | &method_none, | |
63 | &method_pubkey, | |
0fff78ff | 64 | #ifdef GSSAPI |
65 | &method_gssapi, | |
66 | #endif | |
f5799ae1 | 67 | &method_passwd, |
68 | &method_kbdint, | |
69 | &method_hostbased, | |
70 | NULL | |
3c0ef626 | 71 | }; |
72 | ||
73 | /* protocol */ | |
74 | ||
e9a17296 | 75 | static void input_service_request(int, u_int32_t, void *); |
76 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 77 | |
78 | /* helper */ | |
79 | static Authmethod *authmethod_lookup(const char *); | |
80 | static char *authmethods_get(void); | |
700318f3 | 81 | int user_key_allowed(struct passwd *, Key *); |
9cb1827b | 82 | int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); |
3c0ef626 | 83 | |
3c0ef626 | 84 | /* |
85 | * loop until authctxt->success == TRUE | |
86 | */ | |
87 | ||
9cb1827b | 88 | Authctxt * |
89 | do_authentication2(void) | |
3c0ef626 | 90 | { |
9cb1827b | 91 | Authctxt *authctxt = authctxt_new(); |
92 | ||
93 | x_authctxt = authctxt; /*XXX*/ | |
94 | ||
3c0ef626 | 95 | /* challenge-response is implemented via keyboard interactive */ |
96 | if (options.challenge_response_authentication) | |
97 | options.kbd_interactive_authentication = 1; | |
3c0ef626 | 98 | |
e9a17296 | 99 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 100 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
101 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
9cb1827b | 102 | |
103 | return (authctxt); | |
3c0ef626 | 104 | } |
105 | ||
106 | static void | |
e9a17296 | 107 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 108 | { |
109 | Authctxt *authctxt = ctxt; | |
110 | u_int len; | |
41b2f314 | 111 | int acceptit = 0; |
3c0ef626 | 112 | char *service = packet_get_string(&len); |
e9a17296 | 113 | packet_check_eom(); |
3c0ef626 | 114 | |
115 | if (authctxt == NULL) | |
116 | fatal("input_service_request: no authctxt"); | |
117 | ||
118 | if (strcmp(service, "ssh-userauth") == 0) { | |
119 | if (!authctxt->success) { | |
41b2f314 | 120 | acceptit = 1; |
3c0ef626 | 121 | /* now we can handle user-auth requests */ |
122 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
123 | } | |
124 | } | |
125 | /* XXX all other service requests are denied */ | |
126 | ||
41b2f314 | 127 | if (acceptit) { |
3c0ef626 | 128 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
129 | packet_put_cstring(service); | |
130 | packet_send(); | |
131 | packet_write_wait(); | |
132 | } else { | |
133 | debug("bad service request %s", service); | |
134 | packet_disconnect("bad service request %s", service); | |
135 | } | |
136 | xfree(service); | |
137 | } | |
138 | ||
139 | static void | |
e9a17296 | 140 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 141 | { |
142 | Authctxt *authctxt = ctxt; | |
143 | Authmethod *m = NULL; | |
144 | char *user, *service, *method, *style = NULL; | |
145 | int authenticated = 0; | |
146 | ||
147 | if (authctxt == NULL) | |
148 | fatal("input_userauth_request: no authctxt"); | |
149 | ||
150 | user = packet_get_string(NULL); | |
151 | service = packet_get_string(NULL); | |
152 | method = packet_get_string(NULL); | |
153 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
154 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
155 | ||
156 | if ((style = strchr(user, ':')) != NULL) | |
157 | *style++ = 0; | |
158 | ||
159 | if (authctxt->attempt++ == 0) { | |
160 | /* setup auth context */ | |
700318f3 | 161 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
162 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { | |
3c0ef626 | 163 | authctxt->valid = 1; |
164 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
165 | #ifdef USE_PAM | |
0fff78ff | 166 | if (options.use_pam) |
167 | PRIVSEP(start_pam(authctxt->pw->pw_name)); | |
3c0ef626 | 168 | #endif |
169 | } else { | |
0fff78ff | 170 | logit("input_userauth_request: illegal user %s", user); |
171 | authctxt->pw = fakepw(); | |
3c0ef626 | 172 | #ifdef USE_PAM |
0fff78ff | 173 | if (options.use_pam) |
174 | PRIVSEP(start_pam(user)); | |
3c0ef626 | 175 | #endif |
176 | } | |
700318f3 | 177 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
178 | use_privsep ? " [net]" : ""); | |
3c0ef626 | 179 | authctxt->user = xstrdup(user); |
180 | authctxt->service = xstrdup(service); | |
181 | authctxt->style = style ? xstrdup(style) : NULL; | |
700318f3 | 182 | if (use_privsep) |
183 | mm_inform_authserv(service, style); | |
3c0ef626 | 184 | } else if (strcmp(user, authctxt->user) != 0 || |
185 | strcmp(service, authctxt->service) != 0) { | |
186 | packet_disconnect("Change of username or service not allowed: " | |
187 | "(%s,%s) -> (%s,%s)", | |
188 | authctxt->user, authctxt->service, user, service); | |
189 | } | |
190 | /* reset state */ | |
e9a17296 | 191 | auth2_challenge_stop(authctxt); |
0fff78ff | 192 | |
193 | #ifdef GSSAPI | |
194 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
195 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
196 | #endif | |
197 | ||
3c0ef626 | 198 | authctxt->postponed = 0; |
3c0ef626 | 199 | |
200 | /* try to authenticate user */ | |
201 | m = authmethod_lookup(method); | |
202 | if (m != NULL) { | |
203 | debug2("input_userauth_request: try method %s", method); | |
204 | authenticated = m->userauth(authctxt); | |
205 | } | |
206 | userauth_finish(authctxt, authenticated, method); | |
207 | ||
208 | xfree(service); | |
209 | xfree(user); | |
210 | xfree(method); | |
211 | } | |
212 | ||
213 | void | |
214 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
215 | { | |
216 | char *methods; | |
217 | ||
218 | if (!authctxt->valid && authenticated) | |
219 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
220 | authctxt->user); | |
221 | ||
222 | /* Special handling for root */ | |
6a9b3198 | 223 | if (authenticated && authctxt->pw->pw_uid == 0 && |
3c0ef626 | 224 | !auth_root_allowed(method)) |
225 | authenticated = 0; | |
226 | ||
227 | #ifdef USE_PAM | |
0fff78ff | 228 | if (options.use_pam && authenticated && !PRIVSEP(do_pam_account())) |
3c0ef626 | 229 | authenticated = 0; |
0fff78ff | 230 | #endif |
3c0ef626 | 231 | |
41b2f314 | 232 | #ifdef _UNICOS |
233 | if (authenticated && cray_access_denied(authctxt->user)) { | |
234 | authenticated = 0; | |
235 | fatal("Access denied for user %s.",authctxt->user); | |
236 | } | |
237 | #endif /* _UNICOS */ | |
238 | ||
3c0ef626 | 239 | /* Log before sending the reply */ |
240 | auth_log(authctxt, authenticated, method, " ssh2"); | |
241 | ||
242 | if (authctxt->postponed) | |
243 | return; | |
244 | ||
245 | /* XXX todo: check if multiple auth methods are needed */ | |
246 | if (authenticated == 1) { | |
247 | /* turn off userauth */ | |
e9a17296 | 248 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 249 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
250 | packet_send(); | |
251 | packet_write_wait(); | |
252 | /* now we can break out */ | |
253 | authctxt->success = 1; | |
254 | } else { | |
0fff78ff | 255 | if (authctxt->failures++ > AUTH_FAIL_MAX) |
3c0ef626 | 256 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
3c0ef626 | 257 | methods = authmethods_get(); |
258 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
259 | packet_put_cstring(methods); | |
260 | packet_put_char(0); /* XXX partial success, unused */ | |
261 | packet_send(); | |
262 | packet_write_wait(); | |
263 | xfree(methods); | |
264 | } | |
265 | } | |
266 | ||
9cb1827b | 267 | /* get current user */ |
268 | ||
269 | struct passwd* | |
270 | auth_get_user(void) | |
271 | { | |
272 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
273 | } | |
274 | ||
3c0ef626 | 275 | #define DELIM "," |
276 | ||
277 | static char * | |
278 | authmethods_get(void) | |
279 | { | |
e9a17296 | 280 | Buffer b; |
3c0ef626 | 281 | char *list; |
f5799ae1 | 282 | int i; |
3c0ef626 | 283 | |
e9a17296 | 284 | buffer_init(&b); |
f5799ae1 | 285 | for (i = 0; authmethods[i] != NULL; i++) { |
286 | if (strcmp(authmethods[i]->name, "none") == 0) | |
3c0ef626 | 287 | continue; |
f5799ae1 | 288 | if (authmethods[i]->enabled != NULL && |
289 | *(authmethods[i]->enabled) != 0) { | |
e9a17296 | 290 | if (buffer_len(&b) > 0) |
291 | buffer_append(&b, ",", 1); | |
f5799ae1 | 292 | buffer_append(&b, authmethods[i]->name, |
293 | strlen(authmethods[i]->name)); | |
3c0ef626 | 294 | } |
295 | } | |
e9a17296 | 296 | buffer_append(&b, "\0", 1); |
297 | list = xstrdup(buffer_ptr(&b)); | |
298 | buffer_free(&b); | |
3c0ef626 | 299 | return list; |
300 | } | |
301 | ||
302 | static Authmethod * | |
303 | authmethod_lookup(const char *name) | |
304 | { | |
f5799ae1 | 305 | int i; |
306 | ||
3c0ef626 | 307 | if (name != NULL) |
f5799ae1 | 308 | for (i = 0; authmethods[i] != NULL; i++) |
309 | if (authmethods[i]->enabled != NULL && | |
310 | *(authmethods[i]->enabled) != 0 && | |
311 | strcmp(name, authmethods[i]->name) == 0) | |
312 | return authmethods[i]; | |
313 | debug2("Unrecognized authentication method name: %s", | |
314 | name ? name : "NULL"); | |
3c0ef626 | 315 | return NULL; |
316 | } |