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a306f2dd | 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. | |
a306f2dd | 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 | */ | |
bcbf86ec | 24 | |
a306f2dd | 25 | #include "includes.h" |
802e01b8 | 26 | RCSID("$OpenBSD: auth2.c,v 1.98 2003/05/14 02:15:47 markus Exp $"); |
a306f2dd | 27 | |
42f11eb2 | 28 | #include "ssh2.h" |
a306f2dd | 29 | #include "xmalloc.h" |
a306f2dd | 30 | #include "packet.h" |
42f11eb2 | 31 | #include "log.h" |
a306f2dd | 32 | #include "servconf.h" |
33 | #include "compat.h" | |
a306f2dd | 34 | #include "auth.h" |
a306f2dd | 35 | #include "dispatch.h" |
42f11eb2 | 36 | #include "pathnames.h" |
1853d1ef | 37 | #include "monitor_wrap.h" |
a306f2dd | 38 | |
39 | /* import */ | |
40 | extern ServerOptions options; | |
1e3b8b07 | 41 | extern u_char *session_id2; |
a306f2dd | 42 | extern int session_id2_len; |
43 | ||
1853d1ef | 44 | Authctxt *x_authctxt = NULL; |
94ec8c6b | 45 | |
01c24737 | 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; | |
802e01b8 | 53 | #ifdef KRB5 |
54 | extern Authmethod method_kerberos; | |
55 | #endif | |
01c24737 | 56 | |
57 | Authmethod *authmethods[] = { | |
58 | &method_none, | |
59 | &method_pubkey, | |
60 | &method_passwd, | |
61 | &method_kbdint, | |
62 | &method_hostbased, | |
802e01b8 | 63 | #ifdef KRB5 |
64 | &method_kerberos, | |
65 | #endif | |
01c24737 | 66 | NULL |
94ec8c6b | 67 | }; |
68 | ||
a306f2dd | 69 | /* protocol */ |
70 | ||
7819b5c3 | 71 | static void input_service_request(int, u_int32_t, void *); |
72 | static void input_userauth_request(int, u_int32_t, void *); | |
a306f2dd | 73 | |
a306f2dd | 74 | /* helper */ |
396c147e | 75 | static Authmethod *authmethod_lookup(const char *); |
ffb215be | 76 | static char *authmethods_get(void); |
1853d1ef | 77 | int user_key_allowed(struct passwd *, Key *); |
78 | int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
a306f2dd | 79 | |
a306f2dd | 80 | /* |
94ec8c6b | 81 | * loop until authctxt->success == TRUE |
a306f2dd | 82 | */ |
83 | ||
1b34c1b3 | 84 | Authctxt * |
d5bb9418 | 85 | do_authentication2(void) |
a306f2dd | 86 | { |
59c97189 | 87 | Authctxt *authctxt = authctxt_new(); |
88 | ||
94ec8c6b | 89 | x_authctxt = authctxt; /*XXX*/ |
90 | ||
aa8003d6 | 91 | /* challenge-response is implemented via keyboard interactive */ |
5ba55ada | 92 | if (options.challenge_response_authentication) |
d464095c | 93 | options.kbd_interactive_authentication = 1; |
94 | ||
6367063f | 95 | dispatch_init(&dispatch_protocol_error); |
a306f2dd | 96 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
94ec8c6b | 97 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); |
1b34c1b3 | 98 | |
99 | return (authctxt); | |
a306f2dd | 100 | } |
101 | ||
396c147e | 102 | static void |
7819b5c3 | 103 | input_service_request(int type, u_int32_t seq, void *ctxt) |
a306f2dd | 104 | { |
94ec8c6b | 105 | Authctxt *authctxt = ctxt; |
1e3b8b07 | 106 | u_int len; |
7fdc56c5 | 107 | int acceptit = 0; |
a306f2dd | 108 | char *service = packet_get_string(&len); |
95500969 | 109 | packet_check_eom(); |
a306f2dd | 110 | |
94ec8c6b | 111 | if (authctxt == NULL) |
112 | fatal("input_service_request: no authctxt"); | |
113 | ||
a306f2dd | 114 | if (strcmp(service, "ssh-userauth") == 0) { |
94ec8c6b | 115 | if (!authctxt->success) { |
7fdc56c5 | 116 | acceptit = 1; |
a306f2dd | 117 | /* now we can handle user-auth requests */ |
118 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
119 | } | |
120 | } | |
121 | /* XXX all other service requests are denied */ | |
122 | ||
7fdc56c5 | 123 | if (acceptit) { |
a306f2dd | 124 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
125 | packet_put_cstring(service); | |
126 | packet_send(); | |
127 | packet_write_wait(); | |
128 | } else { | |
129 | debug("bad service request %s", service); | |
130 | packet_disconnect("bad service request %s", service); | |
131 | } | |
132 | xfree(service); | |
133 | } | |
134 | ||
396c147e | 135 | static void |
7819b5c3 | 136 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
a306f2dd | 137 | { |
94ec8c6b | 138 | Authctxt *authctxt = ctxt; |
139 | Authmethod *m = NULL; | |
59c97189 | 140 | char *user, *service, *method, *style = NULL; |
a306f2dd | 141 | int authenticated = 0; |
a306f2dd | 142 | |
94ec8c6b | 143 | if (authctxt == NULL) |
144 | fatal("input_userauth_request: no authctxt"); | |
a306f2dd | 145 | |
94ec8c6b | 146 | user = packet_get_string(NULL); |
147 | service = packet_get_string(NULL); | |
148 | method = packet_get_string(NULL); | |
149 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
8abcdba4 | 150 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); |
94ec8c6b | 151 | |
59c97189 | 152 | if ((style = strchr(user, ':')) != NULL) |
153 | *style++ = 0; | |
154 | ||
2b87da3b | 155 | if (authctxt->attempt++ == 0) { |
63284fbb | 156 | /* setup auth context */ |
f7ed12f1 | 157 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
158 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { | |
94ec8c6b | 159 | authctxt->valid = 1; |
160 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
161 | #ifdef USE_PAM | |
7fceb20d | 162 | if (options.use_pam) |
163 | PRIVSEP(start_pam(authctxt->pw->pw_name)); | |
94ec8c6b | 164 | #endif |
165 | } else { | |
bbe88b6d | 166 | logit("input_userauth_request: illegal user %s", user); |
04fc7a67 | 167 | #ifdef USE_PAM |
7fceb20d | 168 | if (options.use_pam) |
169 | PRIVSEP(start_pam(user)); | |
04fc7a67 | 170 | #endif |
94ec8c6b | 171 | } |
5f1f36b5 | 172 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
1853d1ef | 173 | use_privsep ? " [net]" : ""); |
94ec8c6b | 174 | authctxt->user = xstrdup(user); |
175 | authctxt->service = xstrdup(service); | |
2a6a054e | 176 | authctxt->style = style ? xstrdup(style) : NULL; |
1853d1ef | 177 | if (use_privsep) |
178 | mm_inform_authserv(service, style); | |
2a6a054e | 179 | } else if (strcmp(user, authctxt->user) != 0 || |
180 | strcmp(service, authctxt->service) != 0) { | |
181 | packet_disconnect("Change of username or service not allowed: " | |
182 | "(%s,%s) -> (%s,%s)", | |
183 | authctxt->user, authctxt->service, user, service); | |
a306f2dd | 184 | } |
59c97189 | 185 | /* reset state */ |
2f293d43 | 186 | auth2_challenge_stop(authctxt); |
59c97189 | 187 | authctxt->postponed = 0; |
9cd45ea4 | 188 | |
59c97189 | 189 | /* try to authenticate user */ |
94ec8c6b | 190 | m = authmethod_lookup(method); |
191 | if (m != NULL) { | |
192 | debug2("input_userauth_request: try method %s", method); | |
193 | authenticated = m->userauth(authctxt); | |
9cd45ea4 | 194 | } |
d9cd3575 | 195 | userauth_finish(authctxt, authenticated, method); |
196 | ||
197 | xfree(service); | |
198 | xfree(user); | |
199 | xfree(method); | |
200 | } | |
201 | ||
202 | void | |
203 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
204 | { | |
4e81159c | 205 | char *methods; |
206 | ||
59c97189 | 207 | if (!authctxt->valid && authenticated) |
208 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
209 | authctxt->user); | |
9cd45ea4 | 210 | |
94ec8c6b | 211 | /* Special handling for root */ |
5d47f1d4 | 212 | if (authenticated && authctxt->pw->pw_uid == 0 && |
15853e93 | 213 | !auth_root_allowed(method)) |
a306f2dd | 214 | authenticated = 0; |
a306f2dd | 215 | |
ef51930f | 216 | #ifdef _UNICOS |
217 | if (authenticated && cray_access_denied(authctxt->user)) { | |
218 | authenticated = 0; | |
219 | fatal("Access denied for user %s.",authctxt->user); | |
220 | } | |
221 | #endif /* _UNICOS */ | |
222 | ||
94ec8c6b | 223 | /* Log before sending the reply */ |
59c97189 | 224 | auth_log(authctxt, authenticated, method, " ssh2"); |
225 | ||
4e81159c | 226 | if (authctxt->postponed) |
227 | return; | |
228 | ||
229 | /* XXX todo: check if multiple auth methods are needed */ | |
230 | if (authenticated == 1) { | |
231 | /* turn off userauth */ | |
6367063f | 232 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
4e81159c | 233 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
234 | packet_send(); | |
235 | packet_write_wait(); | |
236 | /* now we can break out */ | |
237 | authctxt->success = 1; | |
238 | } else { | |
d7cf277b | 239 | if (authctxt->failures++ > AUTH_FAIL_MAX) |
4e81159c | 240 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
241 | methods = authmethods_get(); | |
242 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
243 | packet_put_cstring(methods); | |
244 | packet_put_char(0); /* XXX partial success, unused */ | |
245 | packet_send(); | |
246 | packet_write_wait(); | |
247 | xfree(methods); | |
248 | } | |
94ec8c6b | 249 | } |
250 | ||
94ec8c6b | 251 | /* get current user */ |
a306f2dd | 252 | |
253 | struct passwd* | |
254 | auth_get_user(void) | |
255 | { | |
94ec8c6b | 256 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; |
a306f2dd | 257 | } |
258 | ||
94ec8c6b | 259 | #define DELIM "," |
260 | ||
ffb215be | 261 | static char * |
94ec8c6b | 262 | authmethods_get(void) |
a306f2dd | 263 | { |
3469eac4 | 264 | Buffer b; |
94ec8c6b | 265 | char *list; |
01c24737 | 266 | int i; |
94ec8c6b | 267 | |
3469eac4 | 268 | buffer_init(&b); |
01c24737 | 269 | for (i = 0; authmethods[i] != NULL; i++) { |
270 | if (strcmp(authmethods[i]->name, "none") == 0) | |
94ec8c6b | 271 | continue; |
01c24737 | 272 | if (authmethods[i]->enabled != NULL && |
273 | *(authmethods[i]->enabled) != 0) { | |
3469eac4 | 274 | if (buffer_len(&b) > 0) |
275 | buffer_append(&b, ",", 1); | |
01c24737 | 276 | buffer_append(&b, authmethods[i]->name, |
277 | strlen(authmethods[i]->name)); | |
a306f2dd | 278 | } |
279 | } | |
3469eac4 | 280 | buffer_append(&b, "\0", 1); |
281 | list = xstrdup(buffer_ptr(&b)); | |
282 | buffer_free(&b); | |
94ec8c6b | 283 | return list; |
284 | } | |
285 | ||
396c147e | 286 | static Authmethod * |
94ec8c6b | 287 | authmethod_lookup(const char *name) |
288 | { | |
01c24737 | 289 | int i; |
290 | ||
94ec8c6b | 291 | if (name != NULL) |
01c24737 | 292 | for (i = 0; authmethods[i] != NULL; i++) |
293 | if (authmethods[i]->enabled != NULL && | |
294 | *(authmethods[i]->enabled) != 0 && | |
295 | strcmp(name, authmethods[i]->name) == 0) | |
296 | return authmethods[i]; | |
297 | debug2("Unrecognized authentication method name: %s", | |
298 | name ? name : "NULL"); | |
94ec8c6b | 299 | return NULL; |
a306f2dd | 300 | } |