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a306f2dd | 1 | /* |
2 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
3 | * All rights reserved | |
bcbf86ec | 4 | * |
5 | * As far as I am concerned, the code I have written for this software | |
6 | * can be used freely for any purpose. Any derived versions of this | |
7 | * software must be clearly marked as such, and if the derived work is | |
8 | * incompatible with the protocol description in the RFC file, it must be | |
9 | * called by a name other than "ssh" or "Secure Shell". | |
a306f2dd | 10 | */ |
11 | ||
12 | #include "includes.h" | |
42f11eb2 | 13 | RCSID("$OpenBSD: auth1.c,v 1.13 2001/01/21 19:05:43 markus Exp $"); |
94ec8c6b | 14 | |
15 | #ifdef HAVE_OSF_SIA | |
16 | # include <sia.h> | |
17 | # include <siad.h> | |
18 | #endif | |
a306f2dd | 19 | |
20 | #include "xmalloc.h" | |
21 | #include "rsa.h" | |
42f11eb2 | 22 | #include "ssh1.h" |
a306f2dd | 23 | #include "packet.h" |
24 | #include "buffer.h" | |
a306f2dd | 25 | #include "mpaux.h" |
42f11eb2 | 26 | #include "log.h" |
a306f2dd | 27 | #include "servconf.h" |
28 | #include "compat.h" | |
29 | #include "auth.h" | |
30 | #include "session.h" | |
31 | ||
32 | /* import */ | |
33 | extern ServerOptions options; | |
34 | extern char *forced_command; | |
94ec8c6b | 35 | |
36 | #ifdef WITH_AIXAUTHENTICATE | |
37 | extern char *aixloginmsg; | |
38 | #endif /* WITH_AIXAUTHENTICATE */ | |
b3f162ba | 39 | #ifdef HAVE_OSF_SIA |
40 | extern int saved_argc; | |
41 | extern char **saved_argv; | |
42 | #endif /* HAVE_OSF_SIA */ | |
a306f2dd | 43 | |
44 | /* | |
45 | * convert ssh auth msg type into description | |
46 | */ | |
47 | char * | |
48 | get_authname(int type) | |
49 | { | |
50 | static char buf[1024]; | |
51 | switch (type) { | |
52 | case SSH_CMSG_AUTH_PASSWORD: | |
53 | return "password"; | |
54 | case SSH_CMSG_AUTH_RSA: | |
55 | return "rsa"; | |
56 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
57 | return "rhosts-rsa"; | |
58 | case SSH_CMSG_AUTH_RHOSTS: | |
59 | return "rhosts"; | |
59c97189 | 60 | case SSH_CMSG_AUTH_TIS: |
61 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
62 | return "challenge-response"; | |
a306f2dd | 63 | #ifdef KRB4 |
64 | case SSH_CMSG_AUTH_KERBEROS: | |
65 | return "kerberos"; | |
a306f2dd | 66 | #endif |
67 | } | |
68 | snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); | |
69 | return buf; | |
70 | } | |
71 | ||
72 | /* | |
59c97189 | 73 | * read packets, try to authenticate the user and |
74 | * return only if authentication is successful | |
a306f2dd | 75 | */ |
76 | void | |
59c97189 | 77 | do_authloop(Authctxt *authctxt) |
a306f2dd | 78 | { |
94ec8c6b | 79 | int authenticated = 0; |
1e3b8b07 | 80 | u_int bits; |
a306f2dd | 81 | RSA *client_host_key; |
82 | BIGNUM *n; | |
94ec8c6b | 83 | char *client_user, *password; |
59c97189 | 84 | char info[1024]; |
1e3b8b07 | 85 | u_int dlen; |
a306f2dd | 86 | int plen, nlen, elen; |
1e3b8b07 | 87 | u_int ulen; |
a306f2dd | 88 | int type = 0; |
59c97189 | 89 | struct passwd *pw = authctxt->pw; |
90 | ||
91 | debug("Attempting authentication for %s%.100s.", | |
92 | authctxt->valid ? "" : "illegal user ", authctxt->user); | |
93 | ||
94 | /* If the user has no password, accept authentication immediately. */ | |
95 | if (options.password_authentication && | |
96 | #ifdef KRB4 | |
97 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && | |
98 | #endif | |
f4ebf0e8 | 99 | #ifdef USE_PAM |
59c97189 | 100 | auth_pam_password(pw, password)) { |
101 | #else | |
102 | auth_password(pw, "")) { | |
103 | #endif | |
104 | auth_log(authctxt, 1, "without authentication", ""); | |
105 | return; | |
106 | } | |
a306f2dd | 107 | |
108 | /* Indicate that authentication is needed. */ | |
109 | packet_start(SSH_SMSG_FAILURE); | |
110 | packet_send(); | |
111 | packet_write_wait(); | |
112 | ||
94ec8c6b | 113 | client_user = NULL; |
114 | ||
59c97189 | 115 | for (;;) { |
94ec8c6b | 116 | /* default to fail */ |
117 | authenticated = 0; | |
118 | ||
59c97189 | 119 | info[0] = '\0'; |
a306f2dd | 120 | |
121 | /* Get a packet from the client. */ | |
122 | type = packet_read(&plen); | |
123 | ||
124 | /* Process the packet. */ | |
125 | switch (type) { | |
126 | #ifdef AFS | |
127 | case SSH_CMSG_HAVE_KERBEROS_TGT: | |
128 | if (!options.kerberos_tgt_passing) { | |
a306f2dd | 129 | verbose("Kerberos tgt passing disabled."); |
130 | break; | |
131 | } else { | |
132 | /* Accept Kerberos tgt. */ | |
133 | char *tgt = packet_get_string(&dlen); | |
134 | packet_integrity_check(plen, 4 + dlen, type); | |
135 | if (!auth_kerberos_tgt(pw, tgt)) | |
59c97189 | 136 | verbose("Kerberos tgt REFUSED for %.100s", authctxt->user); |
a306f2dd | 137 | xfree(tgt); |
138 | } | |
139 | continue; | |
140 | ||
141 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
142 | if (!options.afs_token_passing || !k_hasafs()) { | |
a306f2dd | 143 | verbose("AFS token passing disabled."); |
144 | break; | |
145 | } else { | |
146 | /* Accept AFS token. */ | |
147 | char *token_string = packet_get_string(&dlen); | |
148 | packet_integrity_check(plen, 4 + dlen, type); | |
149 | if (!auth_afs_token(pw, token_string)) | |
59c97189 | 150 | verbose("AFS token REFUSED for %.100s", authctxt->user); |
a306f2dd | 151 | xfree(token_string); |
152 | } | |
153 | continue; | |
154 | #endif /* AFS */ | |
155 | #ifdef KRB4 | |
156 | case SSH_CMSG_AUTH_KERBEROS: | |
157 | if (!options.kerberos_authentication) { | |
a306f2dd | 158 | verbose("Kerberos authentication disabled."); |
159 | break; | |
160 | } else { | |
161 | /* Try Kerberos v4 authentication. */ | |
162 | KTEXT_ST auth; | |
163 | char *tkt_user = NULL; | |
1e3b8b07 | 164 | char *kdata = packet_get_string((u_int *) &auth.length); |
a306f2dd | 165 | packet_integrity_check(plen, 4 + auth.length, type); |
166 | ||
59c97189 | 167 | if (authctxt->valid) { |
168 | if (auth.length < MAX_KTXT_LEN) | |
169 | memcpy(auth.dat, kdata, auth.length); | |
94ec8c6b | 170 | authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
171 | if (authenticated) { | |
59c97189 | 172 | snprintf(info, sizeof info, |
173 | " tktuser %.100s", tkt_user); | |
94ec8c6b | 174 | xfree(tkt_user); |
175 | } | |
a306f2dd | 176 | } |
59c97189 | 177 | xfree(kdata); |
a306f2dd | 178 | } |
179 | break; | |
180 | #endif /* KRB4 */ | |
181 | ||
182 | case SSH_CMSG_AUTH_RHOSTS: | |
183 | if (!options.rhosts_authentication) { | |
184 | verbose("Rhosts authentication disabled."); | |
185 | break; | |
186 | } | |
187 | /* | |
188 | * Get client user name. Note that we just have to | |
189 | * trust the client; this is one reason why rhosts | |
190 | * authentication is insecure. (Another is | |
191 | * IP-spoofing on a local network.) | |
192 | */ | |
193 | client_user = packet_get_string(&ulen); | |
194 | packet_integrity_check(plen, 4 + ulen, type); | |
195 | ||
94ec8c6b | 196 | /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ |
a306f2dd | 197 | authenticated = auth_rhosts(pw, client_user); |
198 | ||
59c97189 | 199 | snprintf(info, sizeof info, " ruser %.100s", client_user); |
a306f2dd | 200 | break; |
201 | ||
202 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
203 | if (!options.rhosts_rsa_authentication) { | |
204 | verbose("Rhosts with RSA authentication disabled."); | |
205 | break; | |
206 | } | |
207 | /* | |
208 | * Get client user name. Note that we just have to | |
209 | * trust the client; root on the client machine can | |
210 | * claim to be any user. | |
211 | */ | |
212 | client_user = packet_get_string(&ulen); | |
213 | ||
214 | /* Get the client host key. */ | |
215 | client_host_key = RSA_new(); | |
216 | if (client_host_key == NULL) | |
217 | fatal("RSA_new failed"); | |
218 | client_host_key->e = BN_new(); | |
219 | client_host_key->n = BN_new(); | |
220 | if (client_host_key->e == NULL || client_host_key->n == NULL) | |
221 | fatal("BN_new failed"); | |
222 | bits = packet_get_int(); | |
223 | packet_get_bignum(client_host_key->e, &elen); | |
224 | packet_get_bignum(client_host_key->n, &nlen); | |
225 | ||
226 | if (bits != BN_num_bits(client_host_key->n)) | |
94ec8c6b | 227 | verbose("Warning: keysize mismatch for client_host_key: " |
0b242b12 | 228 | "actual %d, announced %d", BN_num_bits(client_host_key->n), bits); |
a306f2dd | 229 | packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); |
230 | ||
231 | authenticated = auth_rhosts_rsa(pw, client_user, client_host_key); | |
232 | RSA_free(client_host_key); | |
233 | ||
59c97189 | 234 | snprintf(info, sizeof info, " ruser %.100s", client_user); |
a306f2dd | 235 | break; |
236 | ||
237 | case SSH_CMSG_AUTH_RSA: | |
238 | if (!options.rsa_authentication) { | |
239 | verbose("RSA authentication disabled."); | |
240 | break; | |
241 | } | |
242 | /* RSA authentication requested. */ | |
243 | n = BN_new(); | |
244 | packet_get_bignum(n, &nlen); | |
245 | packet_integrity_check(plen, nlen, type); | |
246 | authenticated = auth_rsa(pw, n); | |
247 | BN_clear_free(n); | |
248 | break; | |
249 | ||
250 | case SSH_CMSG_AUTH_PASSWORD: | |
251 | if (!options.password_authentication) { | |
252 | verbose("Password authentication disabled."); | |
253 | break; | |
254 | } | |
255 | /* | |
256 | * Read user password. It is in plain text, but was | |
257 | * transmitted over the encrypted channel so it is | |
258 | * not visible to an outside observer. | |
259 | */ | |
260 | password = packet_get_string(&dlen); | |
261 | packet_integrity_check(plen, 4 + dlen, type); | |
262 | ||
263 | #ifdef USE_PAM | |
264 | /* Do PAM auth with password */ | |
265 | authenticated = auth_pam_password(pw, password); | |
4d33e531 | 266 | #elif defined(HAVE_OSF_SIA) |
267 | /* Do SIA auth with password */ | |
4d33e531 | 268 | if (sia_validate_user(NULL, saved_argc, saved_argv, |
269 | get_canonical_hostname(), pw->pw_name, NULL, 0, | |
270 | NULL, password) == SIASUCCESS) { | |
271 | authenticated = 1; | |
272 | } | |
273 | #else /* !USE_PAM && !HAVE_OSF_SIA */ | |
94ec8c6b | 274 | /* Try authentication with the password. */ |
a306f2dd | 275 | authenticated = auth_password(pw, password); |
276 | #endif /* USE_PAM */ | |
277 | ||
278 | memset(password, 0, strlen(password)); | |
279 | xfree(password); | |
280 | break; | |
281 | ||
a306f2dd | 282 | case SSH_CMSG_AUTH_TIS: |
283 | debug("rcvd SSH_CMSG_AUTH_TIS"); | |
284 | if (options.skey_authentication == 1) { | |
59c97189 | 285 | char *challenge = get_challenge(authctxt, authctxt->style); |
286 | if (challenge != NULL) { | |
287 | debug("sending challenge '%s'", challenge); | |
a306f2dd | 288 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
59c97189 | 289 | packet_put_cstring(challenge); |
a306f2dd | 290 | packet_send(); |
291 | packet_write_wait(); | |
292 | continue; | |
293 | } | |
294 | } | |
295 | break; | |
42f11eb2 | 296 | |
a306f2dd | 297 | case SSH_CMSG_AUTH_TIS_RESPONSE: |
298 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); | |
299 | if (options.skey_authentication == 1) { | |
300 | char *response = packet_get_string(&dlen); | |
59c97189 | 301 | debug("got response '%s'", response); |
a306f2dd | 302 | packet_integrity_check(plen, 4 + dlen, type); |
59c97189 | 303 | authenticated = verify_response(authctxt, response); |
304 | memset(response, 'r', dlen); | |
a306f2dd | 305 | xfree(response); |
306 | } | |
307 | break; | |
a306f2dd | 308 | |
309 | default: | |
310 | /* | |
311 | * Any unknown messages will be ignored (and failure | |
312 | * returned) during authentication. | |
313 | */ | |
314 | log("Unknown message during authentication: type %d", type); | |
315 | break; | |
316 | } | |
59c97189 | 317 | if (!authctxt->valid && authenticated) |
318 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
319 | authctxt->user); | |
a306f2dd | 320 | |
6005a40c | 321 | #ifdef HAVE_CYGWIN |
94ec8c6b | 322 | if (authenticated && |
9cd45ea4 | 323 | !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,pw->pw_uid)) { |
3c62e7eb | 324 | packet_disconnect("Authentication rejected for uid %d.", |
94ec8c6b | 325 | (int)pw->pw_uid); |
3c62e7eb | 326 | authenticated = 0; |
327 | } | |
3c418020 | 328 | #else |
59c97189 | 329 | /* Special handling for root */ |
330 | if (authenticated && authctxt->pw->pw_uid == 0 && !auth_root_allowed()) | |
331 | authenticated = 0; | |
3c418020 | 332 | #endif |
333 | #ifdef USE_PAM | |
94ec8c6b | 334 | if (authenticated && !do_pam_account(pw->pw_name, client_user)) |
335 | authenticated = 0; | |
336 | #endif | |
a306f2dd | 337 | |
59c97189 | 338 | /* Log before sending the reply */ |
339 | auth_log(authctxt, authenticated, get_authname(type), info); | |
340 | ||
a306f2dd | 341 | if (client_user != NULL) { |
342 | xfree(client_user); | |
343 | client_user = NULL; | |
344 | } | |
345 | ||
94ec8c6b | 346 | if (authenticated) |
347 | return; | |
348 | ||
59c97189 | 349 | if (authctxt->failures++ > AUTH_FAIL_MAX) { |
c1ef8333 | 350 | #ifdef WITH_AIXAUTHENTICATE |
94ec8c6b | 351 | loginfailed(user,get_canonical_hostname(),"ssh"); |
c1ef8333 | 352 | #endif /* WITH_AIXAUTHENTICATE */ |
59c97189 | 353 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
c1ef8333 | 354 | } |
a306f2dd | 355 | |
a306f2dd | 356 | packet_start(SSH_SMSG_FAILURE); |
357 | packet_send(); | |
358 | packet_write_wait(); | |
359 | } | |
360 | } | |
361 | ||
362 | /* | |
363 | * Performs authentication of an incoming connection. Session key has already | |
364 | * been exchanged and encryption is enabled. | |
365 | */ | |
366 | void | |
367 | do_authentication() | |
368 | { | |
59c97189 | 369 | Authctxt *authctxt; |
370 | struct passwd *pw; | |
a306f2dd | 371 | int plen; |
1e3b8b07 | 372 | u_int ulen; |
59c97189 | 373 | char *user, *style = NULL; |
a306f2dd | 374 | |
375 | /* Get the name of the user that we wish to log in as. */ | |
376 | packet_read_expect(&plen, SSH_CMSG_USER); | |
377 | ||
378 | /* Get the user name. */ | |
379 | user = packet_get_string(&ulen); | |
380 | packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); | |
381 | ||
59c97189 | 382 | if ((style = strchr(user, ':')) != NULL) |
383 | *style++ = 0; | |
384 | ||
385 | authctxt = authctxt_new(); | |
386 | authctxt->user = user; | |
387 | authctxt->style = style; | |
388 | ||
a306f2dd | 389 | setproctitle("%s", user); |
390 | ||
391 | #ifdef AFS | |
392 | /* If machine has AFS, set process authentication group. */ | |
393 | if (k_hasafs()) { | |
394 | k_setpag(); | |
395 | k_unlog(); | |
396 | } | |
397 | #endif /* AFS */ | |
398 | ||
399 | /* Verify that the user is a valid user. */ | |
400 | pw = getpwnam(user); | |
94ec8c6b | 401 | if (pw && allowed_user(pw)) { |
59c97189 | 402 | authctxt->valid = 1; |
403 | pw = pwcopy(pw); | |
94ec8c6b | 404 | } else { |
59c97189 | 405 | debug("do_authentication: illegal user %s", user); |
94ec8c6b | 406 | pw = NULL; |
407 | } | |
59c97189 | 408 | authctxt->pw = pw; |
a306f2dd | 409 | |
410 | #ifdef USE_PAM | |
94ec8c6b | 411 | if (pw) |
04fc7a67 | 412 | start_pam(user); |
a306f2dd | 413 | #endif |
414 | ||
415 | /* | |
416 | * If we are not running as root, the user must have the same uid as | |
94ec8c6b | 417 | * the server. (Unless you are running Windows) |
a306f2dd | 418 | */ |
94ec8c6b | 419 | #ifndef HAVE_CYGWIN |
420 | if (getuid() != 0 && pw && pw->pw_uid != getuid()) | |
a306f2dd | 421 | packet_disconnect("Cannot change user when server not running as root."); |
3c62e7eb | 422 | #endif |
a306f2dd | 423 | |
59c97189 | 424 | /* |
425 | * Loop until the user has been authenticated or the connection is | |
426 | * closed, do_authloop() returns only if authentication is successful | |
427 | */ | |
428 | do_authloop(authctxt); | |
a306f2dd | 429 | |
430 | /* The user has been authenticated and accepted. */ | |
94ec8c6b | 431 | packet_start(SSH_SMSG_SUCCESS); |
432 | packet_send(); | |
433 | packet_write_wait(); | |
59c97189 | 434 | |
a306f2dd | 435 | #ifdef WITH_AIXAUTHENTICATE |
c1ef8333 | 436 | /* We don't have a pty yet, so just label the line as "ssh" */ |
59c97189 | 437 | if (loginsuccess(authctxt->user,get_canonical_hostname(),"ssh",&aixloginmsg) < 0) |
c1ef8333 | 438 | aixloginmsg = NULL; |
a306f2dd | 439 | #endif /* WITH_AIXAUTHENTICATE */ |
59c97189 | 440 | |
441 | xfree(authctxt->user); | |
442 | xfree(authctxt); | |
a306f2dd | 443 | |
444 | /* Perform session preparation. */ | |
445 | do_authenticated(pw); | |
446 | } |