auth2.c

   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"
  26 RCSID("$OpenBSD: auth2.c,v 1.82 2002/01/13 17:57:37 markus Exp $");
  27
  28 #include <openssl/evp.h>
  29
  30 #include "ssh2.h"
  31 #include "xmalloc.h"
  32 #include "rsa.h"
  33 #include "sshpty.h"
  34 #include "packet.h"
  35 #include "buffer.h"
  36 #include "log.h"
  37 #include "servconf.h"
  38 #include "compat.h"
  39 #include "channels.h"
  40 #include "bufaux.h"
  41 #include "auth.h"
  42 #include "session.h"
  43 #include "dispatch.h"
  44 #include "key.h"
  45 #include "cipher.h"
  46 #include "kex.h"
  47 #include "pathnames.h"
  48 #include "uidswap.h"
  49 #include "auth-options.h"
  50 #include "misc.h"
  51 #include "hostfile.h"
  52 #include "canohost.h"
  53 #include "match.h"
  54
  55 /* import */
  56 extern ServerOptions options;
  57 extern u_char *session_id2;
  58 extern int session_id2_len;
  59
  60 static Authctxt *x_authctxt = NULL;
  61 static int one = 1;
  62
  63 typedef struct Authmethod Authmethod;
  64 struct Authmethod {
  65         char    *name;
  66         int     (*userauth)(Authctxt *authctxt);
  67         int     *enabled;
  68 };
  69
  70 /* protocol */
  71
  72 static void input_service_request(int, u_int32_t, void *);
  73 static void input_userauth_request(int, u_int32_t, void *);
  74
  75 /* helper */
  76 static Authmethod *authmethod_lookup(const char *);
  77 static char *authmethods_get(void);
  78 static int user_key_allowed(struct passwd *, Key *);
  79 static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
  80
  81 /* auth */
  82 static void userauth_banner(void);
  83 static int userauth_none(Authctxt *);
  84 static int userauth_passwd(Authctxt *);
  85 static int userauth_pubkey(Authctxt *);
  86 static int userauth_hostbased(Authctxt *);
  87 static int userauth_kbdint(Authctxt *);
  88
  89 Authmethod authmethods[] = {
  90         {"none",
  91                 userauth_none,
  92                 &one},
  93         {"publickey",
  94                 userauth_pubkey,
  95                 &options.pubkey_authentication},
  96         {"password",
  97                 userauth_passwd,
  98                 &options.password_authentication},
  99         {"keyboard-interactive",
 100                 userauth_kbdint,
 101                 &options.kbd_interactive_authentication},
 102         {"hostbased",
 103                 userauth_hostbased,
 104                 &options.hostbased_authentication},
 105         {NULL, NULL, NULL}
 106 };
 107
 108 /*
 109  * loop until authctxt->success == TRUE
 110  */
 111
 112 void
 113 do_authentication2(void)
 114 {
 115         Authctxt *authctxt = authctxt_new();
 116
 117         x_authctxt = authctxt;          /*XXX*/
 118
 119         /* challenge-response is implemented via keyboard interactive */
 120         if (options.challenge_response_authentication)
 121                 options.kbd_interactive_authentication = 1;
 122         if (options.pam_authentication_via_kbd_int)
 123                 options.kbd_interactive_authentication = 1;
 124
 125         dispatch_init(&dispatch_protocol_error);
 126         dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
 127         dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
 128         do_authenticated(authctxt);
 129 }
 130
 131 static void
 132 input_service_request(int type, u_int32_t seq, void *ctxt)
 133 {
 134         Authctxt *authctxt = ctxt;
 135         u_int len;
 136         int accept = 0;
 137         char *service = packet_get_string(&len);
 138         packet_check_eom();
 139
 140         if (authctxt == NULL)
 141                 fatal("input_service_request: no authctxt");
 142
 143         if (strcmp(service, "ssh-userauth") == 0) {
 144                 if (!authctxt->success) {
 145                         accept = 1;
 146                         /* now we can handle user-auth requests */
 147                         dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
 148                 }
 149         }
 150         /* XXX all other service requests are denied */
 151
 152         if (accept) {
 153                 packet_start(SSH2_MSG_SERVICE_ACCEPT);
 154                 packet_put_cstring(service);
 155                 packet_send();
 156                 packet_write_wait();
 157         } else {
 158                 debug("bad service request %s", service);
 159                 packet_disconnect("bad service request %s", service);
 160         }
 161         xfree(service);
 162 }
 163
 164 static void
 165 input_userauth_request(int type, u_int32_t seq, void *ctxt)
 166 {
 167         Authctxt *authctxt = ctxt;
 168         Authmethod *m = NULL;
 169         char *user, *service, *method, *style = NULL;
 170         int authenticated = 0;
 171
 172         if (authctxt == NULL)
 173                 fatal("input_userauth_request: no authctxt");
 174
 175         user = packet_get_string(NULL);
 176         service = packet_get_string(NULL);
 177         method = packet_get_string(NULL);
 178         debug("userauth-request for user %s service %s method %s", user, service, method);
 179         debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
 180
 181         if ((style = strchr(user, ':')) != NULL)
 182                 *style++ = 0;
 183
 184         if (authctxt->attempt++ == 0) {
 185                 /* setup auth context */
 186                 struct passwd *pw = NULL;
 187                 pw = getpwnam(user);
 188                 if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) {
 189                         authctxt->pw = pwcopy(pw);
 190                         authctxt->valid = 1;
 191                         debug2("input_userauth_request: setting up authctxt for %s", user);
 192 #ifdef USE_PAM
 193                         start_pam(pw->pw_name);
 194 #endif
 195                 } else {
 196                         log("input_userauth_request: illegal user %s", user);
 197 #ifdef USE_PAM
 198                         start_pam("NOUSER");
 199 #endif
 200                 }
 201                 setproctitle("%s", pw ? user : "unknown");
 202                 authctxt->user = xstrdup(user);
 203                 authctxt->service = xstrdup(service);
 204                 authctxt->style = style ? xstrdup(style) : NULL;
 205         } else if (strcmp(user, authctxt->user) != 0 ||
 206             strcmp(service, authctxt->service) != 0) {
 207                 packet_disconnect("Change of username or service not allowed: "
 208                     "(%s,%s) -> (%s,%s)",
 209                     authctxt->user, authctxt->service, user, service);
 210         }
 211         /* reset state */
 212         auth2_challenge_stop(authctxt);
 213         authctxt->postponed = 0;
 214
 215         /* try to authenticate user */
 216         m = authmethod_lookup(method);
 217         if (m != NULL) {
 218                 debug2("input_userauth_request: try method %s", method);
 219                 authenticated = m->userauth(authctxt);
 220         }
 221         userauth_finish(authctxt, authenticated, method);
 222
 223         xfree(service);
 224         xfree(user);
 225         xfree(method);
 226 }
 227
 228 void
 229 userauth_finish(Authctxt *authctxt, int authenticated, char *method)
 230 {
 231         char *methods;
 232
 233         if (!authctxt->valid && authenticated)
 234                 fatal("INTERNAL ERROR: authenticated invalid user %s",
 235                     authctxt->user);
 236
 237         /* Special handling for root */
 238         if (authenticated && authctxt->pw->pw_uid == 0 &&
 239             !auth_root_allowed(method))
 240                 authenticated = 0;
 241
 242 #ifdef USE_PAM
 243         if (authenticated && authctxt->user && !do_pam_account(authctxt->user,
 244             NULL))
 245                 authenticated = 0;
 246 #endif /* USE_PAM */
 247
 248         /* Log before sending the reply */
 249         auth_log(authctxt, authenticated, method, " ssh2");
 250
 251         if (authctxt->postponed)
 252                 return;
 253
 254         /* XXX todo: check if multiple auth methods are needed */
 255         if (authenticated == 1) {
 256                 /* turn off userauth */
 257                 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
 258                 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
 259                 packet_send();
 260                 packet_write_wait();
 261                 /* now we can break out */
 262                 authctxt->success = 1;
 263         } else {
 264                 if (authctxt->failures++ > AUTH_FAIL_MAX) {
 265 #ifdef WITH_AIXAUTHENTICATE
 266                         loginfailed(authctxt->user,
 267                             get_canonical_hostname(options.reverse_mapping_check),
 268                             "ssh");
 269 #endif /* WITH_AIXAUTHENTICATE */
 270                         packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
 271                 }
 272                 methods = authmethods_get();
 273                 packet_start(SSH2_MSG_USERAUTH_FAILURE);
 274                 packet_put_cstring(methods);
 275                 packet_put_char(0);     /* XXX partial success, unused */
 276                 packet_send();
 277                 packet_write_wait();
 278                 xfree(methods);
 279         }
 280 }
 281
 282 static void
 283 userauth_banner(void)
 284 {
 285         struct stat st;
 286         char *banner = NULL;
 287         off_t len, n;
 288         int fd;
 289
 290         if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
 291                 return;
 292         if ((fd = open(options.banner, O_RDONLY)) < 0)
 293                 return;
 294         if (fstat(fd, &st) < 0)
 295                 goto done;
 296         len = st.st_size;
 297         banner = xmalloc(len + 1);
 298         if ((n = read(fd, banner, len)) < 0)
 299                 goto done;
 300         banner[n] = '\0';
 301         packet_start(SSH2_MSG_USERAUTH_BANNER);
 302         packet_put_cstring(banner);
 303         packet_put_cstring("");         /* language, unused */
 304         packet_send();
 305         debug("userauth_banner: sent");
 306 done:
 307         if (banner)
 308                 xfree(banner);
 309         close(fd);
 310         return;
 311 }
 312
 313 static int
 314 userauth_none(Authctxt *authctxt)
 315 {
 316         /* disable method "none", only allowed one time */
 317         Authmethod *m = authmethod_lookup("none");
 318         if (m != NULL)
 319                 m->enabled = NULL;
 320         packet_check_eom();
 321         userauth_banner();
 322
 323         if (authctxt->valid == 0)
 324                 return(0);
 325
 326 #ifdef HAVE_CYGWIN
 327         if (check_nt_auth(1, authctxt->pw) == 0)
 328                 return(0);
 329 #endif
 330 #ifdef USE_PAM
 331         return auth_pam_password(authctxt->pw, "");
 332 #elif defined(HAVE_OSF_SIA)
 333         return 0;
 334 #else /* !HAVE_OSF_SIA && !USE_PAM */
 335         return auth_password(authctxt, "");
 336 #endif /* USE_PAM */
 337 }
 338
 339 static int
 340 userauth_passwd(Authctxt *authctxt)
 341 {
 342         char *password;
 343         int authenticated = 0;
 344         int change;
 345         u_int len;
 346         change = packet_get_char();
 347         if (change)
 348                 log("password change not supported");
 349         password = packet_get_string(&len);
 350         packet_check_eom();
 351         if (authctxt->valid &&
 352 #ifdef HAVE_CYGWIN
 353             check_nt_auth(1, authctxt->pw) &&
 354 #endif
 355 #ifdef USE_PAM
 356             auth_pam_password(authctxt->pw, password) == 1)
 357 #elif defined(HAVE_OSF_SIA)
 358             auth_sia_password(authctxt->user, password) == 1)
 359 #else /* !USE_PAM && !HAVE_OSF_SIA */
 360             auth_password(authctxt, password) == 1)
 361 #endif /* USE_PAM */
 362                 authenticated = 1;
 363         memset(password, 0, len);
 364         xfree(password);
 365         return authenticated;
 366 }
 367
 368 static int
 369 userauth_kbdint(Authctxt *authctxt)
 370 {
 371         int authenticated = 0;
 372         char *lang, *devs;
 373
 374         lang = packet_get_string(NULL);
 375         devs = packet_get_string(NULL);
 376         packet_check_eom();
 377
 378         debug("keyboard-interactive devs %s", devs);
 379
 380         if (options.challenge_response_authentication)
 381                 authenticated = auth2_challenge(authctxt, devs);
 382
 383 #ifdef USE_PAM
 384         if (authenticated == 0 && options.pam_authentication_via_kbd_int)
 385                 authenticated = auth2_pam(authctxt);
 386 #endif
 387         xfree(devs);
 388         xfree(lang);
 389 #ifdef HAVE_CYGWIN
 390         if (check_nt_auth(0, authctxt->pw) == 0)
 391                 return(0);
 392 #endif
 393         return authenticated;
 394 }
 395
 396 static int
 397 userauth_pubkey(Authctxt *authctxt)
 398 {
 399         Buffer b;
 400         Key *key;
 401         char *pkalg, *pkblob, *sig;
 402         u_int alen, blen, slen;
 403         int have_sig, pktype;
 404         int authenticated = 0;
 405
 406         if (!authctxt->valid) {
 407                 debug2("userauth_pubkey: disabled because of invalid user");
 408                 return 0;
 409         }
 410         have_sig = packet_get_char();
 411         if (datafellows & SSH_BUG_PKAUTH) {
 412                 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
 413                 /* no explicit pkalg given */
 414                 pkblob = packet_get_string(&blen);
 415                 buffer_init(&b);
 416                 buffer_append(&b, pkblob, blen);
 417                 /* so we have to extract the pkalg from the pkblob */
 418                 pkalg = buffer_get_string(&b, &alen);
 419                 buffer_free(&b);
 420         } else {
 421                 pkalg = packet_get_string(&alen);
 422                 pkblob = packet_get_string(&blen);
 423         }
 424         pktype = key_type_from_name(pkalg);
 425         if (pktype == KEY_UNSPEC) {
 426                 /* this is perfectly legal */
 427                 log("userauth_pubkey: unsupported public key algorithm: %s", pkalg);
 428                 xfree(pkalg);
 429                 xfree(pkblob);
 430                 return 0;
 431         }
 432         key = key_from_blob(pkblob, blen);
 433         if (key != NULL) {
 434                 if (have_sig) {
 435                         sig = packet_get_string(&slen);
 436                         packet_check_eom();
 437                         buffer_init(&b);
 438                         if (datafellows & SSH_OLD_SESSIONID) {
 439                                 buffer_append(&b, session_id2, session_id2_len);
 440                         } else {
 441                                 buffer_put_string(&b, session_id2, session_id2_len);
 442                         }
 443                         /* reconstruct packet */
 444                         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 445                         buffer_put_cstring(&b, authctxt->user);
 446                         buffer_put_cstring(&b,
 447                             datafellows & SSH_BUG_PKSERVICE ?
 448                             "ssh-userauth" :
 449                             authctxt->service);
 450                         if (datafellows & SSH_BUG_PKAUTH) {
 451                                 buffer_put_char(&b, have_sig);
 452                         } else {
 453                                 buffer_put_cstring(&b, "publickey");
 454                                 buffer_put_char(&b, have_sig);
 455                                 buffer_put_cstring(&b, pkalg);
 456                         }
 457                         buffer_put_string(&b, pkblob, blen);
 458 #ifdef DEBUG_PK
 459                         buffer_dump(&b);
 460 #endif
 461                         /* test for correct signature */
 462                         if (user_key_allowed(authctxt->pw, key) &&
 463                             key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
 464                                 authenticated = 1;
 465                         buffer_clear(&b);
 466                         xfree(sig);
 467                 } else {
 468                         debug("test whether pkalg/pkblob are acceptable");
 469                         packet_check_eom();
 470
 471                         /* XXX fake reply and always send PK_OK ? */
 472                         /*
 473                          * XXX this allows testing whether a user is allowed
 474                          * to login: if you happen to have a valid pubkey this
 475                          * message is sent. the message is NEVER sent at all
 476                          * if a user is not allowed to login. is this an
 477                          * issue? -markus
 478                          */
 479                         if (user_key_allowed(authctxt->pw, key)) {
 480                                 packet_start(SSH2_MSG_USERAUTH_PK_OK);
 481                                 packet_put_string(pkalg, alen);
 482                                 packet_put_string(pkblob, blen);
 483                                 packet_send();
 484                                 packet_write_wait();
 485                                 authctxt->postponed = 1;
 486                         }
 487                 }
 488                 if (authenticated != 1)
 489                         auth_clear_options();
 490                 key_free(key);
 491         }
 492         debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
 493         xfree(pkalg);
 494         xfree(pkblob);
 495 #ifdef HAVE_CYGWIN
 496         if (check_nt_auth(0, authctxt->pw) == 0)
 497                 return(0);
 498 #endif
 499         return authenticated;
 500 }
 501
 502 static int
 503 userauth_hostbased(Authctxt *authctxt)
 504 {
 505         Buffer b;
 506         Key *key;
 507         char *pkalg, *pkblob, *sig, *cuser, *chost, *service;
 508         u_int alen, blen, slen;
 509         int pktype;
 510         int authenticated = 0;
 511
 512         if (!authctxt->valid) {
 513                 debug2("userauth_hostbased: disabled because of invalid user");
 514                 return 0;
 515         }
 516         pkalg = packet_get_string(&alen);
 517         pkblob = packet_get_string(&blen);
 518         chost = packet_get_string(NULL);
 519         cuser = packet_get_string(NULL);
 520         sig = packet_get_string(&slen);
 521
 522         debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
 523             cuser, chost, pkalg, slen);
 524 #ifdef DEBUG_PK
 525         debug("signature:");
 526         buffer_init(&b);
 527         buffer_append(&b, sig, slen);
 528         buffer_dump(&b);
 529         buffer_free(&b);
 530 #endif
 531         pktype = key_type_from_name(pkalg);
 532         if (pktype == KEY_UNSPEC) {
 533                 /* this is perfectly legal */
 534                 log("userauth_hostbased: unsupported "
 535                     "public key algorithm: %s", pkalg);
 536                 goto done;
 537         }
 538         key = key_from_blob(pkblob, blen);
 539         if (key == NULL) {
 540                 debug("userauth_hostbased: cannot decode key: %s", pkalg);
 541                 goto done;
 542         }
 543         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
 544             authctxt->service;
 545         buffer_init(&b);
 546         buffer_put_string(&b, session_id2, session_id2_len);
 547         /* reconstruct packet */
 548         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 549         buffer_put_cstring(&b, authctxt->user);
 550         buffer_put_cstring(&b, service);
 551         buffer_put_cstring(&b, "hostbased");
 552         buffer_put_string(&b, pkalg, alen);
 553         buffer_put_string(&b, pkblob, blen);
 554         buffer_put_cstring(&b, chost);
 555         buffer_put_cstring(&b, cuser);
 556 #ifdef DEBUG_PK
 557         buffer_dump(&b);
 558 #endif
 559         /* test for allowed key and correct signature */
 560         if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
 561             key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
 562                 authenticated = 1;
 563
 564         buffer_clear(&b);
 565         key_free(key);
 566
 567 done:
 568         debug2("userauth_hostbased: authenticated %d", authenticated);
 569         xfree(pkalg);
 570         xfree(pkblob);
 571         xfree(cuser);
 572         xfree(chost);
 573         xfree(sig);
 574         return authenticated;
 575 }
 576
 577 /* get current user */
 578
 579 struct passwd*
 580 auth_get_user(void)
 581 {
 582         return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
 583 }
 584
 585 #define DELIM   ","
 586
 587 static char *
 588 authmethods_get(void)
 589 {
 590         Authmethod *method = NULL;
 591         Buffer b;
 592         char *list;
 593
 594         buffer_init(&b);
 595         for (method = authmethods; method->name != NULL; method++) {
 596                 if (strcmp(method->name, "none") == 0)
 597                         continue;
 598                 if (method->enabled != NULL && *(method->enabled) != 0) {
 599                         if (buffer_len(&b) > 0)
 600                                 buffer_append(&b, ",", 1);
 601                         buffer_append(&b, method->name, strlen(method->name));
 602                 }
 603         }
 604         buffer_append(&b, "\0", 1);
 605         list = xstrdup(buffer_ptr(&b));
 606         buffer_free(&b);
 607         return list;
 608 }
 609
 610 static Authmethod *
 611 authmethod_lookup(const char *name)
 612 {
 613         Authmethod *method = NULL;
 614         if (name != NULL)
 615                 for (method = authmethods; method->name != NULL; method++)
 616                         if (method->enabled != NULL &&
 617                             *(method->enabled) != 0 &&
 618                             strcmp(name, method->name) == 0)
 619                                 return method;
 620         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
 621         return NULL;
 622 }
 623
 624 /* return 1 if user allows given key */
 625 static int
 626 user_key_allowed2(struct passwd *pw, Key *key, char *file)
 627 {
 628         char line[8192];
 629         int found_key = 0;
 630         FILE *f;
 631         u_long linenum = 0;
 632         struct stat st;
 633         Key *found;
 634         char *fp;
 635
 636         if (pw == NULL)
 637                 return 0;
 638
 639         /* Temporarily use the user's uid. */
 640         temporarily_use_uid(pw);
 641
 642         debug("trying public key file %s", file);
 643
 644         /* Fail quietly if file does not exist */
 645         if (stat(file, &st) < 0) {
 646                 /* Restore the privileged uid. */
 647                 restore_uid();
 648                 return 0;
 649         }
 650         /* Open the file containing the authorized keys. */
 651         f = fopen(file, "r");
 652         if (!f) {
 653                 /* Restore the privileged uid. */
 654                 restore_uid();
 655                 return 0;
 656         }
 657         if (options.strict_modes &&
 658             secure_filename(f, file, pw, line, sizeof(line)) != 0) {
 659                 fclose(f);
 660                 log("Authentication refused: %s", line);
 661                 restore_uid();
 662                 return 0;
 663         }
 664
 665         found_key = 0;
 666         found = key_new(key->type);
 667
 668         while (fgets(line, sizeof(line), f)) {
 669                 char *cp, *options = NULL;
 670                 linenum++;
 671                 /* Skip leading whitespace, empty and comment lines. */
 672                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 673                         ;
 674                 if (!*cp || *cp == '\n' || *cp == '#')
 675                         continue;
 676
 677                 if (key_read(found, &cp) != 1) {
 678                         /* no key?  check if there are options for this key */
 679                         int quoted = 0;
 680                         debug2("user_key_allowed: check options: '%s'", cp);
 681                         options = cp;
 682                         for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
 683                                 if (*cp == '\\' && cp[1] == '"')
 684                                         cp++;   /* Skip both */
 685                                 else if (*cp == '"')
 686                                         quoted = !quoted;
 687                         }
 688                         /* Skip remaining whitespace. */
 689                         for (; *cp == ' ' || *cp == '\t'; cp++)
 690                                 ;
 691                         if (key_read(found, &cp) != 1) {
 692                                 debug2("user_key_allowed: advance: '%s'", cp);
 693                                 /* still no key?  advance to next line*/
 694                                 continue;
 695                         }
 696                 }
 697                 if (key_equal(found, key) &&
 698                     auth_parse_options(pw, options, file, linenum) == 1) {
 699                         found_key = 1;
 700                         debug("matching key found: file %s, line %lu",
 701                             file, linenum);
 702                         fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
 703                         verbose("Found matching %s key: %s",
 704                             key_type(found), fp);
 705                         xfree(fp);
 706                         break;
 707                 }
 708         }
 709         restore_uid();
 710         fclose(f);
 711         key_free(found);
 712         if (!found_key)
 713                 debug2("key not found");
 714         return found_key;
 715 }
 716
 717 /* check whether given key is in .ssh/authorized_keys* */
 718 static int
 719 user_key_allowed(struct passwd *pw, Key *key)
 720 {
 721         int success;
 722         char *file;
 723
 724         file = authorized_keys_file(pw);
 725         success = user_key_allowed2(pw, key, file);
 726         xfree(file);
 727         if (success)
 728                 return success;
 729
 730         /* try suffix "2" for backward compat, too */
 731         file = authorized_keys_file2(pw);
 732         success = user_key_allowed2(pw, key, file);
 733         xfree(file);
 734         return success;
 735 }
 736
 737 /* return 1 if given hostkey is allowed */
 738 static int
 739 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
 740     Key *key)
 741 {
 742         const char *resolvedname, *ipaddr, *lookup;
 743         HostStatus host_status;
 744         int len;
 745
 746         resolvedname = get_canonical_hostname(options.reverse_mapping_check);
 747         ipaddr = get_remote_ipaddr();
 748
 749         debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
 750             chost, resolvedname, ipaddr);
 751
 752         if (options.hostbased_uses_name_from_packet_only) {
 753                 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
 754                         return 0;
 755                 lookup = chost;
 756         } else {
 757                 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
 758                         debug2("stripping trailing dot from chost %s", chost);
 759                         chost[len - 1] = '\0';
 760                 }
 761                 if (strcasecmp(resolvedname, chost) != 0)
 762                         log("userauth_hostbased mismatch: "
 763                             "client sends %s, but we resolve %s to %s",
 764                             chost, ipaddr, resolvedname);
 765                 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
 766                         return 0;
 767                 lookup = resolvedname;
 768         }
 769         debug2("userauth_hostbased: access allowed by auth_rhosts2");
 770
 771         host_status = check_key_in_hostfiles(pw, key, lookup,
 772             _PATH_SSH_SYSTEM_HOSTFILE,
 773             options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
 774
 775         /* backward compat if no key has been found. */
 776         if (host_status == HOST_NEW)
 777                 host_status = check_key_in_hostfiles(pw, key, lookup,
 778                     _PATH_SSH_SYSTEM_HOSTFILE2,
 779                     options.ignore_user_known_hosts ? NULL :
 780                     _PATH_SSH_USER_HOSTFILE2);
 781
 782         return (host_status == HOST_OK);
 783 }
 784