Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 3 | * All rights reserved |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 4 | * Copyright (c) 2000 Markus Friedl. All rights reserved. |
Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 5 | */ |
| 6 | |
| 7 | #include "includes.h" |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 8 | RCSID("$OpenBSD: auth.c,v 1.2 2000/04/06 08:55:22 markus Exp $"); |
Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 9 | |
| 10 | #include "xmalloc.h" |
| 11 | #include "rsa.h" |
| 12 | #include "ssh.h" |
| 13 | #include "pty.h" |
| 14 | #include "packet.h" |
| 15 | #include "buffer.h" |
| 16 | #include "cipher.h" |
| 17 | #include "mpaux.h" |
| 18 | #include "servconf.h" |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 19 | #include "compat.h" |
Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 20 | #include "channels.h" |
| 21 | #include "match.h" |
| 22 | |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 23 | #include "bufaux.h" |
| 24 | #include "ssh2.h" |
| 25 | #include "auth.h" |
Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 26 | #include "session.h" |
| 27 | #include "dispatch.h" |
| 28 | |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 29 | |
Damien Miller | b38eff8 | 2000-04-01 11:09:21 +1000 | [diff] [blame] | 30 | /* import */ |
| 31 | extern ServerOptions options; |
| 32 | extern char *forced_command; |
| 33 | |
| 34 | /* |
| 35 | * Check if the user is allowed to log in via ssh. If user is listed in |
| 36 | * DenyUsers or user's primary group is listed in DenyGroups, false will |
| 37 | * be returned. If AllowUsers isn't empty and user isn't listed there, or |
| 38 | * if AllowGroups isn't empty and user isn't listed there, false will be |
| 39 | * returned. |
| 40 | * If the user's shell is not executable, false will be returned. |
| 41 | * Otherwise true is returned. |
| 42 | */ |
| 43 | static int |
| 44 | allowed_user(struct passwd * pw) |
| 45 | { |
| 46 | struct stat st; |
| 47 | struct group *grp; |
| 48 | int i; |
| 49 | #ifdef WITH_AIXAUTHENTICATE |
| 50 | char *loginmsg; |
| 51 | #endif /* WITH_AIXAUTHENTICATE */ |
| 52 | |
| 53 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ |
| 54 | if (!pw) |
| 55 | return 0; |
| 56 | |
| 57 | /* deny if shell does not exists or is not executable */ |
| 58 | if (stat(pw->pw_shell, &st) != 0) |
| 59 | return 0; |
| 60 | if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)))) |
| 61 | return 0; |
| 62 | |
| 63 | /* Return false if user is listed in DenyUsers */ |
| 64 | if (options.num_deny_users > 0) { |
| 65 | if (!pw->pw_name) |
| 66 | return 0; |
| 67 | for (i = 0; i < options.num_deny_users; i++) |
| 68 | if (match_pattern(pw->pw_name, options.deny_users[i])) |
| 69 | return 0; |
| 70 | } |
| 71 | /* Return false if AllowUsers isn't empty and user isn't listed there */ |
| 72 | if (options.num_allow_users > 0) { |
| 73 | if (!pw->pw_name) |
| 74 | return 0; |
| 75 | for (i = 0; i < options.num_allow_users; i++) |
| 76 | if (match_pattern(pw->pw_name, options.allow_users[i])) |
| 77 | break; |
| 78 | /* i < options.num_allow_users iff we break for loop */ |
| 79 | if (i >= options.num_allow_users) |
| 80 | return 0; |
| 81 | } |
| 82 | /* Get the primary group name if we need it. Return false if it fails */ |
| 83 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| 84 | grp = getgrgid(pw->pw_gid); |
| 85 | if (!grp) |
| 86 | return 0; |
| 87 | |
| 88 | /* Return false if user's group is listed in DenyGroups */ |
| 89 | if (options.num_deny_groups > 0) { |
| 90 | if (!grp->gr_name) |
| 91 | return 0; |
| 92 | for (i = 0; i < options.num_deny_groups; i++) |
| 93 | if (match_pattern(grp->gr_name, options.deny_groups[i])) |
| 94 | return 0; |
| 95 | } |
| 96 | /* |
| 97 | * Return false if AllowGroups isn't empty and user's group |
| 98 | * isn't listed there |
| 99 | */ |
| 100 | if (options.num_allow_groups > 0) { |
| 101 | if (!grp->gr_name) |
| 102 | return 0; |
| 103 | for (i = 0; i < options.num_allow_groups; i++) |
| 104 | if (match_pattern(grp->gr_name, options.allow_groups[i])) |
| 105 | break; |
| 106 | /* i < options.num_allow_groups iff we break for |
| 107 | loop */ |
| 108 | if (i >= options.num_allow_groups) |
| 109 | return 0; |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | #ifdef WITH_AIXAUTHENTICATE |
| 114 | if (loginrestrictions(pw->pw_name,S_LOGIN,NULL,&loginmsg) != 0) |
| 115 | return 0; |
| 116 | #endif /* WITH_AIXAUTHENTICATE */ |
| 117 | |
| 118 | /* We found no reason not to let this user try to log on... */ |
| 119 | return 1; |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * convert ssh auth msg type into description |
| 124 | */ |
| 125 | char * |
| 126 | get_authname(int type) |
| 127 | { |
| 128 | static char buf[1024]; |
| 129 | switch (type) { |
| 130 | case SSH_CMSG_AUTH_PASSWORD: |
| 131 | return "password"; |
| 132 | case SSH_CMSG_AUTH_RSA: |
| 133 | return "rsa"; |
| 134 | case SSH_CMSG_AUTH_RHOSTS_RSA: |
| 135 | return "rhosts-rsa"; |
| 136 | case SSH_CMSG_AUTH_RHOSTS: |
| 137 | return "rhosts"; |
| 138 | #ifdef KRB4 |
| 139 | case SSH_CMSG_AUTH_KERBEROS: |
| 140 | return "kerberos"; |
| 141 | #endif |
| 142 | #ifdef SKEY |
| 143 | case SSH_CMSG_AUTH_TIS_RESPONSE: |
| 144 | return "s/key"; |
| 145 | #endif |
| 146 | } |
| 147 | snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); |
| 148 | return buf; |
| 149 | } |
| 150 | |
| 151 | #define AUTH_FAIL_MAX 6 |
| 152 | #define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2) |
| 153 | #define AUTH_FAIL_MSG "Too many authentication failures for %.100s" |
| 154 | |
| 155 | /* |
| 156 | * The user does not exist or access is denied, |
| 157 | * but fake indication that authentication is needed. |
| 158 | */ |
| 159 | void |
| 160 | do_fake_authloop1(char *user) |
| 161 | { |
| 162 | int attempt = 0; |
| 163 | |
| 164 | log("Faking authloop for illegal user %.200s from %.200s port %d", |
| 165 | user, |
| 166 | get_remote_ipaddr(), |
| 167 | get_remote_port()); |
| 168 | |
| 169 | #ifdef WITH_AIXAUTHENTICATE |
| 170 | if (strncmp(get_authname(type),"password", |
| 171 | strlen(get_authname(type))) == 0) |
| 172 | loginfailed(pw->pw_name,get_canonical_hostname(),"ssh"); |
| 173 | #endif /* WITH_AIXAUTHENTICATE */ |
| 174 | |
| 175 | /* Indicate that authentication is needed. */ |
| 176 | packet_start(SSH_SMSG_FAILURE); |
| 177 | packet_send(); |
| 178 | packet_write_wait(); |
| 179 | |
| 180 | /* |
| 181 | * Keep reading packets, and always respond with a failure. This is |
| 182 | * to avoid disclosing whether such a user really exists. |
| 183 | */ |
| 184 | for (attempt = 1;; attempt++) { |
| 185 | /* Read a packet. This will not return if the client disconnects. */ |
| 186 | int plen; |
| 187 | #ifndef SKEY |
| 188 | (void)packet_read(&plen); |
| 189 | #else /* SKEY */ |
| 190 | int type = packet_read(&plen); |
| 191 | unsigned int dlen; |
| 192 | char *password, *skeyinfo; |
| 193 | /* Try to send a fake s/key challenge. */ |
| 194 | if (options.skey_authentication == 1 && |
| 195 | (skeyinfo = skey_fake_keyinfo(user)) != NULL) { |
| 196 | password = NULL; |
| 197 | if (type == SSH_CMSG_AUTH_TIS) { |
| 198 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
| 199 | packet_put_string(skeyinfo, strlen(skeyinfo)); |
| 200 | packet_send(); |
| 201 | packet_write_wait(); |
| 202 | continue; |
| 203 | } else if (type == SSH_CMSG_AUTH_PASSWORD && |
| 204 | options.password_authentication && |
| 205 | (password = packet_get_string(&dlen)) != NULL && |
| 206 | dlen == 5 && |
| 207 | strncasecmp(password, "s/key", 5) == 0 ) { |
| 208 | packet_send_debug(skeyinfo); |
| 209 | } |
| 210 | if (password != NULL) |
| 211 | xfree(password); |
| 212 | } |
| 213 | #endif |
| 214 | if (attempt > AUTH_FAIL_MAX) |
| 215 | packet_disconnect(AUTH_FAIL_MSG, user); |
| 216 | |
| 217 | /* |
| 218 | * Send failure. This should be indistinguishable from a |
| 219 | * failed authentication. |
| 220 | */ |
| 221 | packet_start(SSH_SMSG_FAILURE); |
| 222 | packet_send(); |
| 223 | packet_write_wait(); |
| 224 | } |
| 225 | /* NOTREACHED */ |
| 226 | abort(); |
| 227 | } |
| 228 | |
| 229 | /* |
| 230 | * read packets and try to authenticate local user *pw. |
| 231 | * return if authentication is successfull |
| 232 | */ |
| 233 | void |
| 234 | do_authloop(struct passwd * pw) |
| 235 | { |
| 236 | int attempt = 0; |
| 237 | unsigned int bits; |
| 238 | RSA *client_host_key; |
| 239 | BIGNUM *n; |
| 240 | char *client_user = NULL, *password = NULL; |
| 241 | char user[1024]; |
| 242 | unsigned int dlen; |
| 243 | int plen, nlen, elen; |
| 244 | unsigned int ulen; |
| 245 | int type = 0; |
| 246 | void (*authlog) (const char *fmt,...) = verbose; |
| 247 | |
| 248 | /* Indicate that authentication is needed. */ |
| 249 | packet_start(SSH_SMSG_FAILURE); |
| 250 | packet_send(); |
| 251 | packet_write_wait(); |
| 252 | |
| 253 | for (attempt = 1;; attempt++) { |
| 254 | int authenticated = 0; |
| 255 | strlcpy(user, "", sizeof user); |
| 256 | |
| 257 | /* Get a packet from the client. */ |
| 258 | type = packet_read(&plen); |
| 259 | |
| 260 | /* Process the packet. */ |
| 261 | switch (type) { |
| 262 | #ifdef AFS |
| 263 | case SSH_CMSG_HAVE_KERBEROS_TGT: |
| 264 | if (!options.kerberos_tgt_passing) { |
| 265 | /* packet_get_all(); */ |
| 266 | verbose("Kerberos tgt passing disabled."); |
| 267 | break; |
| 268 | } else { |
| 269 | /* Accept Kerberos tgt. */ |
| 270 | char *tgt = packet_get_string(&dlen); |
| 271 | packet_integrity_check(plen, 4 + dlen, type); |
| 272 | if (!auth_kerberos_tgt(pw, tgt)) |
| 273 | verbose("Kerberos tgt REFUSED for %s", pw->pw_name); |
| 274 | xfree(tgt); |
| 275 | } |
| 276 | continue; |
| 277 | |
| 278 | case SSH_CMSG_HAVE_AFS_TOKEN: |
| 279 | if (!options.afs_token_passing || !k_hasafs()) { |
| 280 | /* packet_get_all(); */ |
| 281 | verbose("AFS token passing disabled."); |
| 282 | break; |
| 283 | } else { |
| 284 | /* Accept AFS token. */ |
| 285 | char *token_string = packet_get_string(&dlen); |
| 286 | packet_integrity_check(plen, 4 + dlen, type); |
| 287 | if (!auth_afs_token(pw, token_string)) |
| 288 | verbose("AFS token REFUSED for %s", pw->pw_name); |
| 289 | xfree(token_string); |
| 290 | } |
| 291 | continue; |
| 292 | #endif /* AFS */ |
| 293 | #ifdef KRB4 |
| 294 | case SSH_CMSG_AUTH_KERBEROS: |
| 295 | if (!options.kerberos_authentication) { |
| 296 | /* packet_get_all(); */ |
| 297 | verbose("Kerberos authentication disabled."); |
| 298 | break; |
| 299 | } else { |
| 300 | /* Try Kerberos v4 authentication. */ |
| 301 | KTEXT_ST auth; |
| 302 | char *tkt_user = NULL; |
| 303 | char *kdata = packet_get_string((unsigned int *) &auth.length); |
| 304 | packet_integrity_check(plen, 4 + auth.length, type); |
| 305 | |
| 306 | if (auth.length < MAX_KTXT_LEN) |
| 307 | memcpy(auth.dat, kdata, auth.length); |
| 308 | xfree(kdata); |
| 309 | |
| 310 | authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
| 311 | |
| 312 | if (authenticated) { |
| 313 | snprintf(user, sizeof user, " tktuser %s", tkt_user); |
| 314 | xfree(tkt_user); |
| 315 | } |
| 316 | } |
| 317 | break; |
| 318 | #endif /* KRB4 */ |
| 319 | |
| 320 | case SSH_CMSG_AUTH_RHOSTS: |
| 321 | if (!options.rhosts_authentication) { |
| 322 | verbose("Rhosts authentication disabled."); |
| 323 | break; |
| 324 | } |
| 325 | /* |
| 326 | * Get client user name. Note that we just have to |
| 327 | * trust the client; this is one reason why rhosts |
| 328 | * authentication is insecure. (Another is |
| 329 | * IP-spoofing on a local network.) |
| 330 | */ |
| 331 | client_user = packet_get_string(&ulen); |
| 332 | packet_integrity_check(plen, 4 + ulen, type); |
| 333 | |
| 334 | /* Try to authenticate using /etc/hosts.equiv and |
| 335 | .rhosts. */ |
| 336 | authenticated = auth_rhosts(pw, client_user); |
| 337 | |
| 338 | snprintf(user, sizeof user, " ruser %s", client_user); |
| 339 | break; |
| 340 | |
| 341 | case SSH_CMSG_AUTH_RHOSTS_RSA: |
| 342 | if (!options.rhosts_rsa_authentication) { |
| 343 | verbose("Rhosts with RSA authentication disabled."); |
| 344 | break; |
| 345 | } |
| 346 | /* |
| 347 | * Get client user name. Note that we just have to |
| 348 | * trust the client; root on the client machine can |
| 349 | * claim to be any user. |
| 350 | */ |
| 351 | client_user = packet_get_string(&ulen); |
| 352 | |
| 353 | /* Get the client host key. */ |
| 354 | client_host_key = RSA_new(); |
| 355 | if (client_host_key == NULL) |
| 356 | fatal("RSA_new failed"); |
| 357 | client_host_key->e = BN_new(); |
| 358 | client_host_key->n = BN_new(); |
| 359 | if (client_host_key->e == NULL || client_host_key->n == NULL) |
| 360 | fatal("BN_new failed"); |
| 361 | bits = packet_get_int(); |
| 362 | packet_get_bignum(client_host_key->e, &elen); |
| 363 | packet_get_bignum(client_host_key->n, &nlen); |
| 364 | |
| 365 | if (bits != BN_num_bits(client_host_key->n)) |
| 366 | error("Warning: keysize mismatch for client_host_key: " |
| 367 | "actual %d, announced %d", BN_num_bits(client_host_key->n), bits); |
| 368 | packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); |
| 369 | |
| 370 | authenticated = auth_rhosts_rsa(pw, client_user, client_host_key); |
| 371 | RSA_free(client_host_key); |
| 372 | |
| 373 | snprintf(user, sizeof user, " ruser %s", client_user); |
| 374 | break; |
| 375 | |
| 376 | case SSH_CMSG_AUTH_RSA: |
| 377 | if (!options.rsa_authentication) { |
| 378 | verbose("RSA authentication disabled."); |
| 379 | break; |
| 380 | } |
| 381 | /* RSA authentication requested. */ |
| 382 | n = BN_new(); |
| 383 | packet_get_bignum(n, &nlen); |
| 384 | packet_integrity_check(plen, nlen, type); |
| 385 | authenticated = auth_rsa(pw, n); |
| 386 | BN_clear_free(n); |
| 387 | break; |
| 388 | |
| 389 | case SSH_CMSG_AUTH_PASSWORD: |
| 390 | if (!options.password_authentication) { |
| 391 | verbose("Password authentication disabled."); |
| 392 | break; |
| 393 | } |
| 394 | /* |
| 395 | * Read user password. It is in plain text, but was |
| 396 | * transmitted over the encrypted channel so it is |
| 397 | * not visible to an outside observer. |
| 398 | */ |
| 399 | password = packet_get_string(&dlen); |
| 400 | packet_integrity_check(plen, 4 + dlen, type); |
| 401 | |
| 402 | #ifdef USE_PAM |
| 403 | /* Do PAM auth with password */ |
| 404 | authenticated = auth_pam_password(pw, password); |
| 405 | #else /* USE_PAM */ |
| 406 | /* Try authentication with the password. */ |
| 407 | authenticated = auth_password(pw, password); |
| 408 | #endif /* USE_PAM */ |
| 409 | memset(password, 0, strlen(password)); |
| 410 | xfree(password); |
| 411 | break; |
| 412 | |
| 413 | #ifdef SKEY |
| 414 | case SSH_CMSG_AUTH_TIS: |
| 415 | debug("rcvd SSH_CMSG_AUTH_TIS"); |
| 416 | if (options.skey_authentication == 1) { |
| 417 | char *skeyinfo = skey_keyinfo(pw->pw_name); |
| 418 | if (skeyinfo == NULL) { |
| 419 | debug("generating fake skeyinfo for %.100s.", pw->pw_name); |
| 420 | skeyinfo = skey_fake_keyinfo(pw->pw_name); |
| 421 | } |
| 422 | if (skeyinfo != NULL) { |
| 423 | /* we send our s/key- in tis-challenge messages */ |
| 424 | debug("sending challenge '%s'", skeyinfo); |
| 425 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
| 426 | packet_put_string(skeyinfo, strlen(skeyinfo)); |
| 427 | packet_send(); |
| 428 | packet_write_wait(); |
| 429 | continue; |
| 430 | } |
| 431 | } |
| 432 | break; |
| 433 | case SSH_CMSG_AUTH_TIS_RESPONSE: |
| 434 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); |
| 435 | if (options.skey_authentication == 1) { |
| 436 | char *response = packet_get_string(&dlen); |
| 437 | debug("skey response == '%s'", response); |
| 438 | packet_integrity_check(plen, 4 + dlen, type); |
| 439 | authenticated = (skey_haskey(pw->pw_name) == 0 && |
| 440 | skey_passcheck(pw->pw_name, response) != -1); |
| 441 | xfree(response); |
| 442 | } |
| 443 | break; |
| 444 | #else |
| 445 | case SSH_CMSG_AUTH_TIS: |
| 446 | /* TIS Authentication is unsupported */ |
| 447 | log("TIS authentication unsupported."); |
| 448 | break; |
| 449 | #endif |
| 450 | |
| 451 | default: |
| 452 | /* |
| 453 | * Any unknown messages will be ignored (and failure |
| 454 | * returned) during authentication. |
| 455 | */ |
| 456 | log("Unknown message during authentication: type %d", type); |
| 457 | break; |
| 458 | } |
| 459 | |
| 460 | /* |
| 461 | * Check if the user is logging in as root and root logins |
| 462 | * are disallowed. |
| 463 | * Note that root login is allowed for forced commands. |
| 464 | */ |
| 465 | if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) { |
| 466 | if (forced_command) { |
| 467 | log("Root login accepted for forced command."); |
| 468 | } else { |
| 469 | authenticated = 0; |
| 470 | log("ROOT LOGIN REFUSED FROM %.200s", |
| 471 | get_canonical_hostname()); |
| 472 | } |
| 473 | } |
| 474 | |
| 475 | /* Raise logging level */ |
| 476 | if (authenticated || |
| 477 | attempt == AUTH_FAIL_LOG || |
| 478 | type == SSH_CMSG_AUTH_PASSWORD) |
| 479 | authlog = log; |
| 480 | |
| 481 | authlog("%s %s for %.200s from %.200s port %d%s", |
| 482 | authenticated ? "Accepted" : "Failed", |
| 483 | get_authname(type), |
| 484 | pw->pw_uid == 0 ? "ROOT" : pw->pw_name, |
| 485 | get_remote_ipaddr(), |
| 486 | get_remote_port(), |
| 487 | user); |
| 488 | |
| 489 | #ifdef USE_PAM |
| 490 | if (authenticated) { |
| 491 | if (!do_pam_account(pw->pw_name, client_user)) { |
| 492 | if (client_user != NULL) { |
| 493 | xfree(client_user); |
| 494 | client_user = NULL; |
| 495 | } |
| 496 | do_fake_authloop1(pw->pw_name); |
| 497 | } |
| 498 | return; |
| 499 | } |
| 500 | #else /* USE_PAM */ |
| 501 | if (authenticated) { |
| 502 | return; |
| 503 | } |
| 504 | #endif /* USE_PAM */ |
| 505 | |
| 506 | if (client_user != NULL) { |
| 507 | xfree(client_user); |
| 508 | client_user = NULL; |
| 509 | } |
| 510 | |
| 511 | if (attempt > AUTH_FAIL_MAX) |
| 512 | packet_disconnect(AUTH_FAIL_MSG, pw->pw_name); |
| 513 | |
| 514 | /* Send a message indicating that the authentication attempt failed. */ |
| 515 | packet_start(SSH_SMSG_FAILURE); |
| 516 | packet_send(); |
| 517 | packet_write_wait(); |
| 518 | } |
| 519 | } |
| 520 | |
| 521 | /* |
| 522 | * Performs authentication of an incoming connection. Session key has already |
| 523 | * been exchanged and encryption is enabled. |
| 524 | */ |
| 525 | void |
| 526 | do_authentication() |
| 527 | { |
| 528 | struct passwd *pw, pwcopy; |
| 529 | int plen; |
| 530 | unsigned int ulen; |
| 531 | char *user; |
| 532 | #ifdef WITH_AIXAUTHENTICATE |
| 533 | char *loginmsg; |
| 534 | #endif /* WITH_AIXAUTHENTICATE */ |
| 535 | |
| 536 | /* Get the name of the user that we wish to log in as. */ |
| 537 | packet_read_expect(&plen, SSH_CMSG_USER); |
| 538 | |
| 539 | /* Get the user name. */ |
| 540 | user = packet_get_string(&ulen); |
| 541 | packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); |
| 542 | |
| 543 | setproctitle("%s", user); |
| 544 | |
| 545 | #ifdef AFS |
| 546 | /* If machine has AFS, set process authentication group. */ |
| 547 | if (k_hasafs()) { |
| 548 | k_setpag(); |
| 549 | k_unlog(); |
| 550 | } |
| 551 | #endif /* AFS */ |
| 552 | |
| 553 | /* Verify that the user is a valid user. */ |
| 554 | pw = getpwnam(user); |
| 555 | if (!pw || !allowed_user(pw)) |
| 556 | do_fake_authloop1(user); |
| 557 | xfree(user); |
| 558 | |
| 559 | /* Take a copy of the returned structure. */ |
| 560 | memset(&pwcopy, 0, sizeof(pwcopy)); |
| 561 | pwcopy.pw_name = xstrdup(pw->pw_name); |
| 562 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); |
| 563 | pwcopy.pw_uid = pw->pw_uid; |
| 564 | pwcopy.pw_gid = pw->pw_gid; |
| 565 | pwcopy.pw_dir = xstrdup(pw->pw_dir); |
| 566 | pwcopy.pw_shell = xstrdup(pw->pw_shell); |
| 567 | pw = &pwcopy; |
| 568 | |
| 569 | #ifdef USE_PAM |
| 570 | start_pam(pw); |
| 571 | #endif |
| 572 | |
| 573 | /* |
| 574 | * If we are not running as root, the user must have the same uid as |
| 575 | * the server. |
| 576 | */ |
| 577 | if (getuid() != 0 && pw->pw_uid != getuid()) |
| 578 | packet_disconnect("Cannot change user when server not running as root."); |
| 579 | |
| 580 | debug("Attempting authentication for %.100s.", pw->pw_name); |
| 581 | |
| 582 | /* If the user has no password, accept authentication immediately. */ |
| 583 | if (options.password_authentication && |
| 584 | #ifdef KRB4 |
| 585 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
| 586 | #endif /* KRB4 */ |
| 587 | #ifdef USE_PAM |
| 588 | auth_pam_password(pw, "")) { |
| 589 | #else /* USE_PAM */ |
| 590 | auth_password(pw, "")) { |
| 591 | #endif /* USE_PAM */ |
| 592 | /* Authentication with empty password succeeded. */ |
| 593 | log("Login for user %s from %.100s, accepted without authentication.", |
| 594 | pw->pw_name, get_remote_ipaddr()); |
| 595 | } else { |
| 596 | /* Loop until the user has been authenticated or the |
| 597 | connection is closed, do_authloop() returns only if |
| 598 | authentication is successfull */ |
| 599 | do_authloop(pw); |
| 600 | } |
| 601 | |
| 602 | /* The user has been authenticated and accepted. */ |
| 603 | #ifdef WITH_AIXAUTHENTICATE |
| 604 | loginsuccess(user,get_canonical_hostname(),"ssh",&loginmsg); |
| 605 | #endif /* WITH_AIXAUTHENTICATE */ |
| 606 | packet_start(SSH_SMSG_SUCCESS); |
| 607 | packet_send(); |
| 608 | packet_write_wait(); |
| 609 | |
| 610 | /* Perform session preparation. */ |
| 611 | do_authenticated(pw); |
| 612 | } |
Damien Miller | efb4afe | 2000-04-12 18:45:05 +1000 | [diff] [blame] | 613 | |
| 614 | |
| 615 | void input_service_request(int type, int plen); |
| 616 | void input_userauth_request(int type, int plen); |
| 617 | void ssh2_pty_cleanup(void); |
| 618 | |
| 619 | typedef struct Authctxt Authctxt; |
| 620 | struct Authctxt { |
| 621 | char *user; |
| 622 | char *service; |
| 623 | struct passwd pw; |
| 624 | int valid; |
| 625 | }; |
| 626 | static Authctxt *authctxt = NULL; |
| 627 | static int userauth_success = 0; |
| 628 | |
| 629 | struct passwd* |
| 630 | auth_get_user(void) |
| 631 | { |
| 632 | return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL; |
| 633 | } |
| 634 | struct passwd* |
| 635 | auth_set_user(char *u, char *s) |
| 636 | { |
| 637 | struct passwd *pw, *copy; |
| 638 | |
| 639 | if (authctxt == NULL) { |
| 640 | authctxt = xmalloc(sizeof(*authctxt)); |
| 641 | authctxt->valid = 0; |
| 642 | authctxt->user = xstrdup(u); |
| 643 | authctxt->service = xstrdup(s); |
| 644 | setproctitle("%s", u); |
| 645 | pw = getpwnam(u); |
| 646 | if (!pw || !allowed_user(pw)) { |
| 647 | log("auth_set_user: bad user %s", u); |
| 648 | return NULL; |
| 649 | } |
| 650 | #ifdef USE_PAM |
| 651 | start_pam(pw); |
| 652 | #endif |
| 653 | copy = &authctxt->pw; |
| 654 | memset(copy, 0, sizeof(*copy)); |
| 655 | copy->pw_name = xstrdup(pw->pw_name); |
| 656 | copy->pw_passwd = xstrdup(pw->pw_passwd); |
| 657 | copy->pw_uid = pw->pw_uid; |
| 658 | copy->pw_gid = pw->pw_gid; |
| 659 | copy->pw_dir = xstrdup(pw->pw_dir); |
| 660 | copy->pw_shell = xstrdup(pw->pw_shell); |
| 661 | authctxt->valid = 1; |
| 662 | } else { |
| 663 | if (strcmp(u, authctxt->user) != 0 || |
| 664 | strcmp(s, authctxt->service) != 0) { |
| 665 | log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)", |
| 666 | u, s, authctxt->user, authctxt->service); |
| 667 | return NULL; |
| 668 | } |
| 669 | } |
| 670 | return auth_get_user(); |
| 671 | } |
| 672 | |
| 673 | static void |
| 674 | protocol_error(int type, int plen) |
| 675 | { |
| 676 | log("auth: protocol error: type %d plen %d", type, plen); |
| 677 | packet_start(SSH2_MSG_UNIMPLEMENTED); |
| 678 | packet_put_int(0); |
| 679 | packet_send(); |
| 680 | packet_write_wait(); |
| 681 | } |
| 682 | void |
| 683 | input_service_request(int type, int plen) |
| 684 | { |
| 685 | unsigned int len; |
| 686 | int accept = 0; |
| 687 | char *service = packet_get_string(&len); |
| 688 | |
| 689 | if (strcmp(service, "ssh-userauth") == 0) { |
| 690 | if (!userauth_success) { |
| 691 | accept = 1; |
| 692 | /* now we can handle user-auth requests */ |
| 693 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); |
| 694 | } |
| 695 | } |
| 696 | /* XXX all other service requests are denied */ |
| 697 | |
| 698 | if (accept) { |
| 699 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
| 700 | packet_put_cstring(service); |
| 701 | packet_send(); |
| 702 | packet_write_wait(); |
| 703 | } else { |
| 704 | debug("bad service request %s", service); |
| 705 | packet_disconnect("bad service request %s", service); |
| 706 | } |
| 707 | xfree(service); |
| 708 | } |
| 709 | void |
| 710 | input_userauth_request(int type, int plen) |
| 711 | { |
| 712 | static int try = 0; |
| 713 | unsigned int len; |
| 714 | int c, authenticated = 0; |
| 715 | char *user, *service, *method; |
| 716 | struct passwd *pw; |
| 717 | |
| 718 | if (++try == AUTH_FAIL_MAX) |
| 719 | packet_disconnect("too many failed userauth_requests"); |
| 720 | |
| 721 | user = packet_get_string(&len); |
| 722 | service = packet_get_string(&len); |
| 723 | method = packet_get_string(&len); |
| 724 | debug("userauth-request for user %s service %s method %s", user, service, method); |
| 725 | |
| 726 | /* XXX we only allow the ssh-connection service */ |
| 727 | pw = auth_set_user(user, service); |
| 728 | if (pw && strcmp(service, "ssh-connection")==0) { |
| 729 | if (strcmp(method, "none") == 0 && try == 1) { |
| 730 | #ifdef USE_PAM |
| 731 | /* Do PAM auth with password */ |
| 732 | authenticated = auth_pam_password(pw, ""); |
| 733 | #else /* USE_PAM */ |
| 734 | /* Try authentication with the password. */ |
| 735 | authenticated = auth_password(pw, ""); |
| 736 | #endif /* USE_PAM */ |
| 737 | } else if (strcmp(method, "password") == 0) { |
| 738 | char *password; |
| 739 | c = packet_get_char(); |
| 740 | if (c) |
| 741 | debug("password change not supported"); |
| 742 | password = packet_get_string(&len); |
| 743 | #ifdef USE_PAM |
| 744 | /* Do PAM auth with password */ |
| 745 | authenticated = auth_pam_password(pw, password); |
| 746 | #else /* USE_PAM */ |
| 747 | /* Try authentication with the password. */ |
| 748 | authenticated = auth_password(pw, password); |
| 749 | #endif /* USE_PAM */ |
| 750 | memset(password, 0, len); |
| 751 | xfree(password); |
| 752 | } else if (strcmp(method, "publickey") == 0) { |
| 753 | /* XXX TODO */ |
| 754 | char *pkalg; |
| 755 | char *pkblob; |
| 756 | c = packet_get_char(); |
| 757 | pkalg = packet_get_string(&len); |
| 758 | pkblob = packet_get_string(&len); |
| 759 | xfree(pkalg); |
| 760 | xfree(pkblob); |
| 761 | } |
| 762 | } |
| 763 | /* XXX check if other auth methods are needed */ |
| 764 | if (authenticated) { |
| 765 | /* turn off userauth */ |
| 766 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); |
| 767 | /* success! */ |
| 768 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
| 769 | packet_send(); |
| 770 | packet_write_wait(); |
| 771 | log("userauth success for %s", user); |
| 772 | /* now we can break out */ |
| 773 | userauth_success = 1; |
| 774 | } else { |
| 775 | packet_start(SSH2_MSG_USERAUTH_FAILURE); |
| 776 | packet_put_cstring("password"); |
| 777 | packet_put_char(0); /* partial success */ |
| 778 | packet_send(); |
| 779 | packet_write_wait(); |
| 780 | } |
| 781 | xfree(service); |
| 782 | xfree(user); |
| 783 | xfree(method); |
| 784 | } |
| 785 | void |
| 786 | do_authentication2() |
| 787 | { |
| 788 | dispatch_init(&protocol_error); |
| 789 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
| 790 | dispatch_run(DISPATCH_BLOCK, &userauth_success); |
| 791 | do_authenticated2(); |
| 792 | } |