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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" | |
6a9b3198 | 26 | RCSID("$OpenBSD: auth2.c,v 1.96 2003/02/06 21:22:43 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 | |
39 | /* import */ | |
40 | extern ServerOptions options; | |
41 | extern u_char *session_id2; | |
42 | extern int session_id2_len; | |
43 | ||
700318f3 | 44 | Authctxt *x_authctxt = NULL; |
3c0ef626 | 45 | |
f5799ae1 | 46 | /* methods */ |
47 | ||
48 | extern Authmethod method_none; | |
49 | extern Authmethod method_pubkey; | |
50 | extern Authmethod method_passwd; | |
51 | extern Authmethod method_kbdint; | |
52 | extern Authmethod method_hostbased; | |
53 | ||
54 | Authmethod *authmethods[] = { | |
55 | &method_none, | |
56 | &method_pubkey, | |
57 | &method_passwd, | |
58 | &method_kbdint, | |
59 | &method_hostbased, | |
60 | NULL | |
3c0ef626 | 61 | }; |
62 | ||
63 | /* protocol */ | |
64 | ||
e9a17296 | 65 | static void input_service_request(int, u_int32_t, void *); |
66 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 67 | |
68 | /* helper */ | |
69 | static Authmethod *authmethod_lookup(const char *); | |
70 | static char *authmethods_get(void); | |
700318f3 | 71 | int user_key_allowed(struct passwd *, Key *); |
72 | int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
3c0ef626 | 73 | |
3c0ef626 | 74 | /* |
75 | * loop until authctxt->success == TRUE | |
76 | */ | |
77 | ||
700318f3 | 78 | Authctxt * |
e9a17296 | 79 | do_authentication2(void) |
3c0ef626 | 80 | { |
81 | Authctxt *authctxt = authctxt_new(); | |
82 | ||
83 | x_authctxt = authctxt; /*XXX*/ | |
84 | ||
85 | /* challenge-response is implemented via keyboard interactive */ | |
86 | if (options.challenge_response_authentication) | |
87 | options.kbd_interactive_authentication = 1; | |
88 | if (options.pam_authentication_via_kbd_int) | |
89 | options.kbd_interactive_authentication = 1; | |
700318f3 | 90 | if (use_privsep) |
91 | options.pam_authentication_via_kbd_int = 0; | |
3c0ef626 | 92 | |
e9a17296 | 93 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 94 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
95 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
700318f3 | 96 | |
97 | return (authctxt); | |
3c0ef626 | 98 | } |
99 | ||
100 | static void | |
e9a17296 | 101 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 102 | { |
103 | Authctxt *authctxt = ctxt; | |
104 | u_int len; | |
41b2f314 | 105 | int acceptit = 0; |
3c0ef626 | 106 | char *service = packet_get_string(&len); |
e9a17296 | 107 | packet_check_eom(); |
3c0ef626 | 108 | |
109 | if (authctxt == NULL) | |
110 | fatal("input_service_request: no authctxt"); | |
111 | ||
112 | if (strcmp(service, "ssh-userauth") == 0) { | |
113 | if (!authctxt->success) { | |
41b2f314 | 114 | acceptit = 1; |
3c0ef626 | 115 | /* now we can handle user-auth requests */ |
116 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
117 | } | |
118 | } | |
119 | /* XXX all other service requests are denied */ | |
120 | ||
41b2f314 | 121 | if (acceptit) { |
3c0ef626 | 122 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
123 | packet_put_cstring(service); | |
124 | packet_send(); | |
125 | packet_write_wait(); | |
126 | } else { | |
127 | debug("bad service request %s", service); | |
128 | packet_disconnect("bad service request %s", service); | |
129 | } | |
130 | xfree(service); | |
131 | } | |
132 | ||
133 | static void | |
e9a17296 | 134 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 135 | { |
136 | Authctxt *authctxt = ctxt; | |
137 | Authmethod *m = NULL; | |
138 | char *user, *service, *method, *style = NULL; | |
139 | int authenticated = 0; | |
140 | ||
141 | if (authctxt == NULL) | |
142 | fatal("input_userauth_request: no authctxt"); | |
143 | ||
144 | user = packet_get_string(NULL); | |
145 | service = packet_get_string(NULL); | |
146 | method = packet_get_string(NULL); | |
147 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
148 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
149 | ||
150 | if ((style = strchr(user, ':')) != NULL) | |
151 | *style++ = 0; | |
152 | ||
153 | if (authctxt->attempt++ == 0) { | |
154 | /* setup auth context */ | |
700318f3 | 155 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
156 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { | |
3c0ef626 | 157 | authctxt->valid = 1; |
158 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
159 | #ifdef USE_PAM | |
700318f3 | 160 | PRIVSEP(start_pam(authctxt->pw->pw_name)); |
3c0ef626 | 161 | #endif |
162 | } else { | |
163 | log("input_userauth_request: illegal user %s", user); | |
164 | #ifdef USE_PAM | |
700318f3 | 165 | PRIVSEP(start_pam("NOUSER")); |
3c0ef626 | 166 | #endif |
167 | } | |
700318f3 | 168 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
169 | use_privsep ? " [net]" : ""); | |
3c0ef626 | 170 | authctxt->user = xstrdup(user); |
171 | authctxt->service = xstrdup(service); | |
172 | authctxt->style = style ? xstrdup(style) : NULL; | |
700318f3 | 173 | if (use_privsep) |
174 | mm_inform_authserv(service, style); | |
3c0ef626 | 175 | } else if (strcmp(user, authctxt->user) != 0 || |
176 | strcmp(service, authctxt->service) != 0) { | |
177 | packet_disconnect("Change of username or service not allowed: " | |
178 | "(%s,%s) -> (%s,%s)", | |
179 | authctxt->user, authctxt->service, user, service); | |
180 | } | |
181 | /* reset state */ | |
e9a17296 | 182 | auth2_challenge_stop(authctxt); |
3c0ef626 | 183 | authctxt->postponed = 0; |
3c0ef626 | 184 | |
185 | /* try to authenticate user */ | |
186 | m = authmethod_lookup(method); | |
187 | if (m != NULL) { | |
188 | debug2("input_userauth_request: try method %s", method); | |
189 | authenticated = m->userauth(authctxt); | |
190 | } | |
191 | userauth_finish(authctxt, authenticated, method); | |
192 | ||
193 | xfree(service); | |
194 | xfree(user); | |
195 | xfree(method); | |
196 | } | |
197 | ||
198 | void | |
199 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
200 | { | |
201 | char *methods; | |
202 | ||
203 | if (!authctxt->valid && authenticated) | |
204 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
205 | authctxt->user); | |
206 | ||
207 | /* Special handling for root */ | |
6a9b3198 | 208 | if (authenticated && authctxt->pw->pw_uid == 0 && |
3c0ef626 | 209 | !auth_root_allowed(method)) |
210 | authenticated = 0; | |
211 | ||
212 | #ifdef USE_PAM | |
700318f3 | 213 | if (!use_privsep && authenticated && authctxt->user && |
214 | !do_pam_account(authctxt->user, NULL)) | |
3c0ef626 | 215 | authenticated = 0; |
216 | #endif /* USE_PAM */ | |
217 | ||
41b2f314 | 218 | #ifdef _UNICOS |
219 | if (authenticated && cray_access_denied(authctxt->user)) { | |
220 | authenticated = 0; | |
221 | fatal("Access denied for user %s.",authctxt->user); | |
222 | } | |
223 | #endif /* _UNICOS */ | |
224 | ||
3c0ef626 | 225 | /* Log before sending the reply */ |
226 | auth_log(authctxt, authenticated, method, " ssh2"); | |
227 | ||
228 | if (authctxt->postponed) | |
229 | return; | |
230 | ||
231 | /* XXX todo: check if multiple auth methods are needed */ | |
232 | if (authenticated == 1) { | |
233 | /* turn off userauth */ | |
e9a17296 | 234 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 235 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
236 | packet_send(); | |
237 | packet_write_wait(); | |
238 | /* now we can break out */ | |
239 | authctxt->success = 1; | |
240 | } else { | |
241 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
3c0ef626 | 242 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
243 | } | |
41b2f314 | 244 | #ifdef _UNICOS |
245 | if (strcmp(method, "password") == 0) | |
246 | cray_login_failure(authctxt->user, IA_UDBERR); | |
247 | #endif /* _UNICOS */ | |
3c0ef626 | 248 | methods = authmethods_get(); |
249 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
250 | packet_put_cstring(methods); | |
251 | packet_put_char(0); /* XXX partial success, unused */ | |
252 | packet_send(); | |
253 | packet_write_wait(); | |
254 | xfree(methods); | |
255 | } | |
256 | } | |
257 | ||
3c0ef626 | 258 | /* get current user */ |
259 | ||
260 | struct passwd* | |
261 | auth_get_user(void) | |
262 | { | |
263 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
264 | } | |
265 | ||
266 | #define DELIM "," | |
267 | ||
268 | static char * | |
269 | authmethods_get(void) | |
270 | { | |
e9a17296 | 271 | Buffer b; |
3c0ef626 | 272 | char *list; |
f5799ae1 | 273 | int i; |
3c0ef626 | 274 | |
e9a17296 | 275 | buffer_init(&b); |
f5799ae1 | 276 | for (i = 0; authmethods[i] != NULL; i++) { |
277 | if (strcmp(authmethods[i]->name, "none") == 0) | |
3c0ef626 | 278 | continue; |
f5799ae1 | 279 | if (authmethods[i]->enabled != NULL && |
280 | *(authmethods[i]->enabled) != 0) { | |
e9a17296 | 281 | if (buffer_len(&b) > 0) |
282 | buffer_append(&b, ",", 1); | |
f5799ae1 | 283 | buffer_append(&b, authmethods[i]->name, |
284 | strlen(authmethods[i]->name)); | |
3c0ef626 | 285 | } |
286 | } | |
e9a17296 | 287 | buffer_append(&b, "\0", 1); |
288 | list = xstrdup(buffer_ptr(&b)); | |
289 | buffer_free(&b); | |
3c0ef626 | 290 | return list; |
291 | } | |
292 | ||
293 | static Authmethod * | |
294 | authmethod_lookup(const char *name) | |
295 | { | |
f5799ae1 | 296 | int i; |
297 | ||
3c0ef626 | 298 | if (name != NULL) |
f5799ae1 | 299 | for (i = 0; authmethods[i] != NULL; i++) |
300 | if (authmethods[i]->enabled != NULL && | |
301 | *(authmethods[i]->enabled) != 0 && | |
302 | strcmp(name, authmethods[i]->name) == 0) | |
303 | return authmethods[i]; | |
304 | debug2("Unrecognized authentication method name: %s", | |
305 | name ? name : "NULL"); | |
3c0ef626 | 306 | return NULL; |
307 | } |