1 /*- 2 * Copyright (c) 2002 Networks Associates Technology, Inc. 3 * All rights reserved. 4 * 5 * This software was developed for the FreeBSD Project by ThinkSec AS and 6 * NAI Labs, the Security Research Division of Network Associates, Inc. 7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 8 * DARPA CHATS research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 /* 32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org> 33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au> 34 * 35 * Permission to use, copy, modify, and distribute this software for any 36 * purpose with or without fee is hereby granted, provided that the above 37 * copyright notice and this permission notice appear in all copies. 38 * 39 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 40 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 41 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 42 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 43 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 44 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 45 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 46 */ 47 48 /* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */ 49 50 #include "includes.h" 51 52 #include <sys/types.h> 53 #include <sys/stat.h> 54 #include <sys/wait.h> 55 56 #include <errno.h> 57 #include <signal.h> 58 #include <stdarg.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #ifdef USE_PAM 64 #if defined(HAVE_SECURITY_PAM_APPL_H) 65 #include <security/pam_appl.h> 66 #elif defined (HAVE_PAM_PAM_APPL_H) 67 #include <pam/pam_appl.h> 68 #endif 69 70 #if !defined(SSHD_PAM_SERVICE) 71 extern char *__progname; 72 # define SSHD_PAM_SERVICE __progname 73 #endif 74 75 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 76 #ifdef PAM_SUN_CODEBASE 77 # define sshpam_const /* Solaris, HP-UX, SunOS */ 78 #else 79 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 80 #endif 81 82 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 83 #ifdef PAM_SUN_CODEBASE 84 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 85 #else 86 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 87 #endif 88 89 #include "xmalloc.h" 90 #include "sshbuf.h" 91 #include "ssherr.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "auth-pam.h" 95 #include "canohost.h" 96 #include "log.h" 97 #include "msg.h" 98 #include "packet.h" 99 #include "misc.h" 100 #include "servconf.h" 101 #include "ssh2.h" 102 #include "auth-options.h" 103 #include "misc.h" 104 #ifdef GSSAPI 105 #include "ssh-gss.h" 106 #endif 107 #include "monitor_wrap.h" 108 #include "blacklist_client.h" 109 110 extern ServerOptions options; 111 extern struct sshbuf *loginmsg; 112 extern u_int utmp_len; 113 114 /* so we don't silently change behaviour */ 115 #ifdef USE_POSIX_THREADS 116 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 117 #endif 118 119 /* 120 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 121 * and generally a bad idea. Use at own risk and do not expect support if 122 * this breaks. 123 */ 124 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 125 #include <pthread.h> 126 /* 127 * Avoid namespace clash when *not* using pthreads for systems *with* 128 * pthreads, which unconditionally define pthread_t via sys/types.h 129 * (e.g. Linux) 130 */ 131 typedef pthread_t sp_pthread_t; 132 #else 133 typedef pid_t sp_pthread_t; 134 #define pthread_exit fake_pthread_exit 135 #define pthread_create fake_pthread_create 136 #define pthread_cancel fake_pthread_cancel 137 #define pthread_join fake_pthread_join 138 #endif 139 140 struct pam_ctxt { 141 sp_pthread_t pam_thread; 142 int pam_psock; 143 int pam_csock; 144 int pam_done; 145 }; 146 147 static void sshpam_free_ctx(void *); 148 static struct pam_ctxt *cleanup_ctxt; 149 150 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 151 /* 152 * Simulate threads with processes. 153 */ 154 155 static int sshpam_thread_status = -1; 156 static sshsig_t sshpam_oldsig; 157 158 static void 159 sshpam_sigchld_handler(int sig) 160 { 161 ssh_signal(SIGCHLD, SIG_DFL); 162 if (cleanup_ctxt == NULL) 163 return; /* handler called after PAM cleanup, shouldn't happen */ 164 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 165 <= 0) { 166 /* PAM thread has not exitted, privsep slave must have */ 167 kill(cleanup_ctxt->pam_thread, SIGTERM); 168 while (waitpid(cleanup_ctxt->pam_thread, 169 &sshpam_thread_status, 0) == -1) { 170 if (errno == EINTR) 171 continue; 172 return; 173 } 174 } 175 if (WIFSIGNALED(sshpam_thread_status) && 176 WTERMSIG(sshpam_thread_status) == SIGTERM) 177 return; /* terminated by pthread_cancel */ 178 if (!WIFEXITED(sshpam_thread_status)) 179 sigdie("PAM: authentication thread exited unexpectedly"); 180 if (WEXITSTATUS(sshpam_thread_status) != 0) 181 sigdie("PAM: authentication thread exited uncleanly"); 182 } 183 184 /* ARGSUSED */ 185 static void 186 pthread_exit(void *value) 187 { 188 _exit(0); 189 } 190 191 /* ARGSUSED */ 192 static int 193 pthread_create(sp_pthread_t *thread, const void *attr, 194 void *(*thread_start)(void *), void *arg) 195 { 196 pid_t pid; 197 struct pam_ctxt *ctx = arg; 198 199 sshpam_thread_status = -1; 200 switch ((pid = fork())) { 201 case -1: 202 error("fork(): %s", strerror(errno)); 203 return errno; 204 case 0: 205 close(ctx->pam_psock); 206 ctx->pam_psock = -1; 207 thread_start(arg); 208 _exit(1); 209 default: 210 *thread = pid; 211 close(ctx->pam_csock); 212 ctx->pam_csock = -1; 213 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler); 214 return (0); 215 } 216 } 217 218 static int 219 pthread_cancel(sp_pthread_t thread) 220 { 221 ssh_signal(SIGCHLD, sshpam_oldsig); 222 return (kill(thread, SIGTERM)); 223 } 224 225 /* ARGSUSED */ 226 static int 227 pthread_join(sp_pthread_t thread, void **value) 228 { 229 int status; 230 231 if (sshpam_thread_status != -1) 232 return (sshpam_thread_status); 233 ssh_signal(SIGCHLD, sshpam_oldsig); 234 while (waitpid(thread, &status, 0) == -1) { 235 if (errno == EINTR) 236 continue; 237 fatal("%s: waitpid: %s", __func__, strerror(errno)); 238 } 239 return (status); 240 } 241 #endif 242 243 244 static pam_handle_t *sshpam_handle = NULL; 245 static int sshpam_err = 0; 246 static int sshpam_authenticated = 0; 247 static int sshpam_session_open = 0; 248 static int sshpam_cred_established = 0; 249 static int sshpam_account_status = -1; 250 static int sshpam_maxtries_reached = 0; 251 static char **sshpam_env = NULL; 252 static Authctxt *sshpam_authctxt = NULL; 253 static const char *sshpam_password = NULL; 254 static char *sshpam_rhost = NULL; 255 static char *sshpam_laddr = NULL; 256 257 /* Some PAM implementations don't implement this */ 258 #ifndef HAVE_PAM_GETENVLIST 259 static char ** 260 pam_getenvlist(pam_handle_t *pamh) 261 { 262 /* 263 * XXX - If necessary, we can still support environment passing 264 * for platforms without pam_getenvlist by searching for known 265 * env vars (e.g. KRB5CCNAME) from the PAM environment. 266 */ 267 return NULL; 268 } 269 #endif 270 271 #ifndef HAVE_PAM_PUTENV 272 static int 273 pam_putenv(pam_handle_t *pamh, const char *name_value) 274 { 275 return PAM_SUCCESS; 276 } 277 #endif /* HAVE_PAM_PUTENV */ 278 279 /* 280 * Some platforms, notably Solaris, do not enforce password complexity 281 * rules during pam_chauthtok() if the real uid of the calling process 282 * is 0, on the assumption that it's being called by "passwd" run by root. 283 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 284 * the right thing. 285 */ 286 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 287 static int 288 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 289 { 290 int result; 291 292 if (sshpam_authctxt == NULL) 293 fatal("PAM: sshpam_authctxt not initialized"); 294 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 295 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 296 result = pam_chauthtok(pamh, flags); 297 if (setreuid(0, -1) == -1) 298 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 299 return result; 300 } 301 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 302 #endif 303 304 static void 305 sshpam_password_change_required(int reqd) 306 { 307 extern struct sshauthopt *auth_opts; 308 static int saved_port, saved_agent, saved_x11; 309 310 debug3("%s %d", __func__, reqd); 311 if (sshpam_authctxt == NULL) 312 fatal("%s: PAM authctxt not initialized", __func__); 313 sshpam_authctxt->force_pwchange = reqd; 314 if (reqd) { 315 saved_port = auth_opts->permit_port_forwarding_flag; 316 saved_agent = auth_opts->permit_agent_forwarding_flag; 317 saved_x11 = auth_opts->permit_x11_forwarding_flag; 318 auth_opts->permit_port_forwarding_flag = 0; 319 auth_opts->permit_agent_forwarding_flag = 0; 320 auth_opts->permit_x11_forwarding_flag = 0; 321 } else { 322 if (saved_port) 323 auth_opts->permit_port_forwarding_flag = saved_port; 324 if (saved_agent) 325 auth_opts->permit_agent_forwarding_flag = saved_agent; 326 if (saved_x11) 327 auth_opts->permit_x11_forwarding_flag = saved_x11; 328 } 329 } 330 331 /* Import regular and PAM environment from subprocess */ 332 static void 333 import_environments(struct sshbuf *b) 334 { 335 char *env; 336 u_int n, i, num_env; 337 int r; 338 339 debug3("PAM: %s entering", __func__); 340 341 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 342 /* Import variables set by do_pam_account */ 343 if ((r = sshbuf_get_u32(b, &n)) != 0) 344 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 345 if (n > INT_MAX) 346 fatal("%s: invalid PAM account status %u", __func__, n); 347 sshpam_account_status = (int)n; 348 if ((r = sshbuf_get_u32(b, &n)) != 0) 349 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 350 sshpam_password_change_required(n != 0); 351 352 /* Import environment from subprocess */ 353 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 354 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 355 if (num_env > 1024) 356 fatal("%s: received %u environment variables, expected <= 1024", 357 __func__, num_env); 358 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 359 debug3("PAM: num env strings %d", num_env); 360 for(i = 0; i < num_env; i++) { 361 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 362 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 363 } 364 sshpam_env[num_env] = NULL; 365 366 /* Import PAM environment from subprocess */ 367 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 368 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 369 debug("PAM: num PAM env strings %d", num_env); 370 for (i = 0; i < num_env; i++) { 371 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 372 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 373 /* Errors are not fatal here */ 374 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 375 error("PAM: pam_putenv: %s", 376 pam_strerror(sshpam_handle, r)); 377 } 378 /* 379 * XXX this possibly leaks env because it is not documented 380 * what pam_putenv() does with it. Does it copy it? Does it 381 * take ownweship? We don't know, so it's safest just to leak. 382 */ 383 } 384 #endif 385 } 386 387 /* 388 * Conversation function for authentication thread. 389 */ 390 static int 391 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 392 struct pam_response **resp, void *data) 393 { 394 struct sshbuf *buffer; 395 struct pam_ctxt *ctxt; 396 struct pam_response *reply; 397 int r, i; 398 u_char status; 399 400 debug3("PAM: %s entering, %d messages", __func__, n); 401 *resp = NULL; 402 403 if (data == NULL) { 404 error("PAM: conversation function passed a null context"); 405 return (PAM_CONV_ERR); 406 } 407 ctxt = data; 408 if (n <= 0 || n > PAM_MAX_NUM_MSG) 409 return (PAM_CONV_ERR); 410 411 if ((reply = calloc(n, sizeof(*reply))) == NULL) 412 return PAM_CONV_ERR; 413 if ((buffer = sshbuf_new()) == NULL) { 414 free(reply); 415 return PAM_CONV_ERR; 416 } 417 418 for (i = 0; i < n; ++i) { 419 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 420 case PAM_PROMPT_ECHO_OFF: 421 case PAM_PROMPT_ECHO_ON: 422 if ((r = sshbuf_put_cstring(buffer, 423 PAM_MSG_MEMBER(msg, i, msg))) != 0) 424 fatal("%s: buffer error: %s", 425 __func__, ssh_err(r)); 426 if (ssh_msg_send(ctxt->pam_csock, 427 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 428 goto fail; 429 430 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 431 goto fail; 432 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 433 fatal("%s: buffer error: %s", 434 __func__, ssh_err(r)); 435 if (status != PAM_AUTHTOK) 436 goto fail; 437 if ((r = sshbuf_get_cstring(buffer, 438 &reply[i].resp, NULL)) != 0) 439 fatal("%s: buffer error: %s", 440 __func__, ssh_err(r)); 441 break; 442 case PAM_ERROR_MSG: 443 case PAM_TEXT_INFO: 444 if ((r = sshbuf_put_cstring(buffer, 445 PAM_MSG_MEMBER(msg, i, msg))) != 0) 446 fatal("%s: buffer error: %s", 447 __func__, ssh_err(r)); 448 if (ssh_msg_send(ctxt->pam_csock, 449 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 450 goto fail; 451 break; 452 default: 453 goto fail; 454 } 455 sshbuf_reset(buffer); 456 } 457 sshbuf_free(buffer); 458 *resp = reply; 459 return (PAM_SUCCESS); 460 461 fail: 462 for(i = 0; i < n; i++) { 463 free(reply[i].resp); 464 } 465 free(reply); 466 sshbuf_free(buffer); 467 return (PAM_CONV_ERR); 468 } 469 470 /* 471 * Authentication thread. 472 */ 473 static void * 474 sshpam_thread(void *ctxtp) 475 { 476 struct pam_ctxt *ctxt = ctxtp; 477 struct sshbuf *buffer = NULL; 478 struct pam_conv sshpam_conv; 479 int r, flags = (options.permit_empty_passwd == 0 ? 480 PAM_DISALLOW_NULL_AUTHTOK : 0); 481 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 482 extern char **environ; 483 char **env_from_pam; 484 u_int i; 485 const char *pam_user; 486 const char **ptr_pam_user = &pam_user; 487 char *tz = getenv("TZ"); 488 489 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 490 (sshpam_const void **)ptr_pam_user); 491 if (sshpam_err != PAM_SUCCESS) 492 goto auth_fail; 493 494 environ[0] = NULL; 495 if (tz != NULL) 496 if (setenv("TZ", tz, 1) == -1) 497 error("PAM: could not set TZ environment: %s", 498 strerror(errno)); 499 500 if (sshpam_authctxt != NULL) { 501 setproctitle("%s [pam]", 502 sshpam_authctxt->valid ? pam_user : "unknown"); 503 } 504 #endif 505 506 sshpam_conv.conv = sshpam_thread_conv; 507 sshpam_conv.appdata_ptr = ctxt; 508 509 if (sshpam_authctxt == NULL) 510 fatal("%s: PAM authctxt not initialized", __func__); 511 512 if ((buffer = sshbuf_new()) == NULL) 513 fatal("%s: sshbuf_new failed", __func__); 514 515 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 516 (const void *)&sshpam_conv); 517 if (sshpam_err != PAM_SUCCESS) 518 goto auth_fail; 519 sshpam_err = pam_authenticate(sshpam_handle, flags); 520 if (sshpam_err == PAM_MAXTRIES) 521 sshpam_set_maxtries_reached(1); 522 if (sshpam_err != PAM_SUCCESS) 523 goto auth_fail; 524 525 if (!do_pam_account()) { 526 sshpam_err = PAM_ACCT_EXPIRED; 527 goto auth_fail; 528 } 529 if (sshpam_authctxt->force_pwchange) { 530 sshpam_err = pam_chauthtok(sshpam_handle, 531 PAM_CHANGE_EXPIRED_AUTHTOK); 532 if (sshpam_err != PAM_SUCCESS) 533 goto auth_fail; 534 sshpam_password_change_required(0); 535 } 536 537 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 538 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 539 540 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 541 /* Export variables set by do_pam_account */ 542 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 543 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 544 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 545 546 /* Export any environment strings set in child */ 547 for (i = 0; environ[i] != NULL; i++) { 548 /* Count */ 549 if (i > INT_MAX) 550 fatal("%s: too many environment strings", __func__); 551 } 552 if ((r = sshbuf_put_u32(buffer, i)) != 0) 553 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 554 for (i = 0; environ[i] != NULL; i++) { 555 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 556 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 557 } 558 /* Export any environment strings set by PAM in child */ 559 env_from_pam = pam_getenvlist(sshpam_handle); 560 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 561 /* Count */ 562 if (i > INT_MAX) 563 fatal("%s: too many PAM environment strings", __func__); 564 } 565 if ((r = sshbuf_put_u32(buffer, i)) != 0) 566 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 567 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 568 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 569 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 570 } 571 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 572 573 /* XXX - can't do much about an error here */ 574 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 575 sshbuf_free(buffer); 576 pthread_exit(NULL); 577 578 auth_fail: 579 if ((r = sshbuf_put_cstring(buffer, 580 pam_strerror(sshpam_handle, sshpam_err))) != 0) 581 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 582 /* XXX - can't do much about an error here */ 583 if (sshpam_err == PAM_ACCT_EXPIRED) 584 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 585 else if (sshpam_maxtries_reached) 586 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 587 else 588 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 589 sshbuf_free(buffer); 590 pthread_exit(NULL); 591 592 return (NULL); /* Avoid warning for non-pthread case */ 593 } 594 595 void 596 sshpam_thread_cleanup(void) 597 { 598 struct pam_ctxt *ctxt = cleanup_ctxt; 599 600 debug3("PAM: %s entering", __func__); 601 if (ctxt != NULL && ctxt->pam_thread != 0) { 602 pthread_cancel(ctxt->pam_thread); 603 pthread_join(ctxt->pam_thread, NULL); 604 close(ctxt->pam_psock); 605 close(ctxt->pam_csock); 606 memset(ctxt, 0, sizeof(*ctxt)); 607 cleanup_ctxt = NULL; 608 } 609 } 610 611 static int 612 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 613 struct pam_response **resp, void *data) 614 { 615 debug3("PAM: %s entering, %d messages", __func__, n); 616 return (PAM_CONV_ERR); 617 } 618 619 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 620 621 static int 622 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 623 struct pam_response **resp, void *data) 624 { 625 struct pam_response *reply; 626 int r, i; 627 628 debug3("PAM: %s called with %d messages", __func__, n); 629 *resp = NULL; 630 631 if (n <= 0 || n > PAM_MAX_NUM_MSG) 632 return (PAM_CONV_ERR); 633 634 if ((reply = calloc(n, sizeof(*reply))) == NULL) 635 return (PAM_CONV_ERR); 636 637 for (i = 0; i < n; ++i) { 638 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 639 case PAM_ERROR_MSG: 640 case PAM_TEXT_INFO: 641 if ((r = sshbuf_putf(loginmsg, "%s\n", 642 PAM_MSG_MEMBER(msg, i, msg))) != 0) 643 fatal("%s: buffer error: %s", 644 __func__, ssh_err(r)); 645 reply[i].resp_retcode = PAM_SUCCESS; 646 break; 647 default: 648 goto fail; 649 } 650 } 651 *resp = reply; 652 return (PAM_SUCCESS); 653 654 fail: 655 for(i = 0; i < n; i++) { 656 free(reply[i].resp); 657 } 658 free(reply); 659 return (PAM_CONV_ERR); 660 } 661 662 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 663 664 void 665 sshpam_cleanup(void) 666 { 667 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 668 return; 669 debug("PAM: cleanup"); 670 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 671 if (sshpam_session_open) { 672 debug("PAM: closing session"); 673 pam_close_session(sshpam_handle, PAM_SILENT); 674 sshpam_session_open = 0; 675 } 676 if (sshpam_cred_established) { 677 debug("PAM: deleting credentials"); 678 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 679 sshpam_cred_established = 0; 680 } 681 sshpam_authenticated = 0; 682 pam_end(sshpam_handle, sshpam_err); 683 sshpam_handle = NULL; 684 } 685 686 static int 687 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 688 { 689 const char *pam_user, *user = authctxt->user; 690 const char **ptr_pam_user = &pam_user; 691 int r; 692 693 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 694 /* Protect buggy PAM implementations from excessively long usernames */ 695 if (strlen(user) >= PAM_MAX_RESP_SIZE) 696 fatal("Username too long from %s port %d", 697 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 698 #endif 699 if (sshpam_handle == NULL) { 700 if (ssh == NULL) { 701 fatal("%s: called initially with no " 702 "packet context", __func__); 703 } 704 } if (sshpam_handle != NULL) { 705 /* We already have a PAM context; check if the user matches */ 706 sshpam_err = pam_get_item(sshpam_handle, 707 PAM_USER, (sshpam_const void **)ptr_pam_user); 708 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 709 return (0); 710 pam_end(sshpam_handle, sshpam_err); 711 sshpam_handle = NULL; 712 } 713 debug("PAM: initializing for \"%s\"", user); 714 sshpam_err = 715 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 716 sshpam_authctxt = authctxt; 717 718 if (sshpam_err != PAM_SUCCESS) { 719 pam_end(sshpam_handle, sshpam_err); 720 sshpam_handle = NULL; 721 return (-1); 722 } 723 724 if (ssh != NULL && sshpam_rhost == NULL) { 725 /* 726 * We need to cache these as we don't have packet context 727 * during the kbdint flow. 728 */ 729 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 730 options.use_dns)); 731 sshpam_laddr = get_local_ipaddr( 732 ssh_packet_get_connection_in(ssh)); 733 } 734 if (sshpam_rhost != NULL) { 735 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 736 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 737 sshpam_rhost); 738 if (sshpam_err != PAM_SUCCESS) { 739 pam_end(sshpam_handle, sshpam_err); 740 sshpam_handle = NULL; 741 return (-1); 742 } 743 } 744 if (ssh != NULL && sshpam_laddr != NULL) { 745 char *conninfo; 746 747 /* Put SSH_CONNECTION in the PAM environment too */ 748 xasprintf(&conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 749 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 750 sshpam_laddr, ssh_local_port(ssh)); 751 if ((r = pam_putenv(sshpam_handle, conninfo)) != PAM_SUCCESS) 752 logit("pam_putenv: %s", pam_strerror(sshpam_handle, r)); 753 free(conninfo); 754 } 755 756 #ifdef PAM_TTY_KLUDGE 757 /* 758 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 759 * sshd doesn't set the tty until too late in the auth process and 760 * may not even set one (for tty-less connections) 761 */ 762 debug("PAM: setting PAM_TTY to \"ssh\""); 763 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 764 if (sshpam_err != PAM_SUCCESS) { 765 pam_end(sshpam_handle, sshpam_err); 766 sshpam_handle = NULL; 767 return (-1); 768 } 769 #endif 770 return (0); 771 } 772 773 static void 774 expose_authinfo(const char *caller) 775 { 776 char *auth_info; 777 778 /* 779 * Expose authentication information to PAM. 780 * The environment variable is versioned. Please increment the 781 * version suffix if the format of session_info changes. 782 */ 783 if (sshpam_authctxt->session_info == NULL) 784 auth_info = xstrdup(""); 785 else if ((auth_info = sshbuf_dup_string( 786 sshpam_authctxt->session_info)) == NULL) 787 fatal("%s: sshbuf_dup_string failed", __func__); 788 789 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 790 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 791 free(auth_info); 792 } 793 794 static void * 795 sshpam_init_ctx(Authctxt *authctxt) 796 { 797 struct pam_ctxt *ctxt; 798 int result, socks[2]; 799 800 debug3("PAM: %s entering", __func__); 801 /* 802 * Refuse to start if we don't have PAM enabled or do_pam_account 803 * has previously failed. 804 */ 805 if (!options.use_pam || sshpam_account_status == 0) 806 return NULL; 807 808 /* Initialize PAM */ 809 if (sshpam_init(NULL, authctxt) == -1) { 810 error("PAM: initialization failed"); 811 return (NULL); 812 } 813 814 expose_authinfo(__func__); 815 ctxt = xcalloc(1, sizeof *ctxt); 816 817 /* Start the authentication thread */ 818 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 819 error("PAM: failed create sockets: %s", strerror(errno)); 820 free(ctxt); 821 return (NULL); 822 } 823 ctxt->pam_psock = socks[0]; 824 ctxt->pam_csock = socks[1]; 825 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 826 if (result != 0) { 827 error("PAM: failed to start authentication thread: %s", 828 strerror(result)); 829 close(socks[0]); 830 close(socks[1]); 831 free(ctxt); 832 return (NULL); 833 } 834 cleanup_ctxt = ctxt; 835 return (ctxt); 836 } 837 838 static int 839 sshpam_query(void *ctx, char **name, char **info, 840 u_int *num, char ***prompts, u_int **echo_on) 841 { 842 struct sshbuf *buffer; 843 struct pam_ctxt *ctxt = ctx; 844 size_t plen; 845 u_char type; 846 char *msg; 847 size_t len, mlen; 848 int r; 849 850 debug3("PAM: %s entering", __func__); 851 if ((buffer = sshbuf_new()) == NULL) 852 fatal("%s: sshbuf_new failed", __func__); 853 *name = xstrdup(""); 854 *info = xstrdup(""); 855 *prompts = xmalloc(sizeof(char *)); 856 **prompts = NULL; 857 plen = 0; 858 *echo_on = xmalloc(sizeof(u_int)); 859 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 860 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 861 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 862 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 863 switch (type) { 864 case PAM_PROMPT_ECHO_ON: 865 case PAM_PROMPT_ECHO_OFF: 866 *num = 1; 867 len = plen + mlen + 1; 868 **prompts = xreallocarray(**prompts, 1, len); 869 strlcpy(**prompts + plen, msg, len - plen); 870 plen += mlen; 871 **echo_on = (type == PAM_PROMPT_ECHO_ON); 872 free(msg); 873 sshbuf_free(buffer); 874 return (0); 875 case PAM_ERROR_MSG: 876 case PAM_TEXT_INFO: 877 /* accumulate messages */ 878 len = plen + mlen + 2; 879 **prompts = xreallocarray(**prompts, 1, len); 880 strlcpy(**prompts + plen, msg, len - plen); 881 plen += mlen; 882 strlcat(**prompts + plen, "\n", len - plen); 883 plen++; 884 free(msg); 885 break; 886 case PAM_ACCT_EXPIRED: 887 case PAM_MAXTRIES: 888 if (type == PAM_ACCT_EXPIRED) 889 sshpam_account_status = 0; 890 if (type == PAM_MAXTRIES) 891 sshpam_set_maxtries_reached(1); 892 /* FALLTHROUGH */ 893 case PAM_AUTH_ERR: 894 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 895 if (**prompts != NULL && strlen(**prompts) != 0) { 896 free(*info); 897 *info = **prompts; 898 **prompts = NULL; 899 *num = 0; 900 **echo_on = 0; 901 ctxt->pam_done = -1; 902 free(msg); 903 sshbuf_free(buffer); 904 return 0; 905 } 906 /* FALLTHROUGH */ 907 case PAM_SUCCESS: 908 if (**prompts != NULL) { 909 /* drain any accumulated messages */ 910 debug("PAM: %s", **prompts); 911 if ((r = sshbuf_put(loginmsg, **prompts, 912 strlen(**prompts))) != 0) 913 fatal("%s: buffer error: %s", 914 __func__, ssh_err(r)); 915 free(**prompts); 916 **prompts = NULL; 917 } 918 if (type == PAM_SUCCESS) { 919 if (!sshpam_authctxt->valid || 920 (sshpam_authctxt->pw->pw_uid == 0 && 921 options.permit_root_login != PERMIT_YES)) 922 fatal("Internal error: PAM auth " 923 "succeeded when it should have " 924 "failed"); 925 import_environments(buffer); 926 *num = 0; 927 **echo_on = 0; 928 ctxt->pam_done = 1; 929 free(msg); 930 sshbuf_free(buffer); 931 return (0); 932 } 933 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER, 934 sshpam_authctxt->user); 935 error("PAM: %s for %s%.100s from %.100s", msg, 936 sshpam_authctxt->valid ? "" : "illegal user ", 937 sshpam_authctxt->user, sshpam_rhost); 938 /* FALLTHROUGH */ 939 default: 940 *num = 0; 941 **echo_on = 0; 942 free(msg); 943 ctxt->pam_done = -1; 944 sshbuf_free(buffer); 945 return (-1); 946 } 947 } 948 sshbuf_free(buffer); 949 return (-1); 950 } 951 952 /* 953 * Returns a junk password of identical length to that the user supplied. 954 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 955 * vary processing time in proportion to password length. 956 */ 957 static char * 958 fake_password(const char *wire_password) 959 { 960 const char junk[] = "\b\n\r\177INCORRECT"; 961 char *ret = NULL; 962 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 963 964 if (l >= INT_MAX) 965 fatal("%s: password length too long: %zu", __func__, l); 966 967 ret = malloc(l + 1); 968 if (ret == NULL) 969 return NULL; 970 for (i = 0; i < l; i++) 971 ret[i] = junk[i % (sizeof(junk) - 1)]; 972 ret[i] = '\0'; 973 return ret; 974 } 975 976 /* XXX - see also comment in auth-chall.c:verify_response */ 977 static int 978 sshpam_respond(void *ctx, u_int num, char **resp) 979 { 980 struct sshbuf *buffer; 981 struct pam_ctxt *ctxt = ctx; 982 char *fake; 983 int r; 984 985 debug2("PAM: %s entering, %u responses", __func__, num); 986 switch (ctxt->pam_done) { 987 case 1: 988 sshpam_authenticated = 1; 989 return (0); 990 case 0: 991 break; 992 default: 993 return (-1); 994 } 995 if (num != 1) { 996 error("PAM: expected one response, got %u", num); 997 return (-1); 998 } 999 if ((buffer = sshbuf_new()) == NULL) 1000 fatal("%s: sshbuf_new failed", __func__); 1001 if (sshpam_authctxt->valid && 1002 (sshpam_authctxt->pw->pw_uid != 0 || 1003 options.permit_root_login == PERMIT_YES)) { 1004 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 1005 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1006 } else { 1007 fake = fake_password(*resp); 1008 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1009 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1010 free(fake); 1011 } 1012 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1013 sshbuf_free(buffer); 1014 return (-1); 1015 } 1016 sshbuf_free(buffer); 1017 return (1); 1018 } 1019 1020 static void 1021 sshpam_free_ctx(void *ctxtp) 1022 { 1023 struct pam_ctxt *ctxt = ctxtp; 1024 1025 debug3("PAM: %s entering", __func__); 1026 sshpam_thread_cleanup(); 1027 free(ctxt); 1028 /* 1029 * We don't call sshpam_cleanup() here because we may need the PAM 1030 * handle at a later stage, e.g. when setting up a session. It's 1031 * still on the cleanup list, so pam_end() *will* be called before 1032 * the server process terminates. 1033 */ 1034 } 1035 1036 KbdintDevice sshpam_device = { 1037 "pam", 1038 sshpam_init_ctx, 1039 sshpam_query, 1040 sshpam_respond, 1041 sshpam_free_ctx 1042 }; 1043 1044 KbdintDevice mm_sshpam_device = { 1045 "pam", 1046 mm_sshpam_init_ctx, 1047 mm_sshpam_query, 1048 mm_sshpam_respond, 1049 mm_sshpam_free_ctx 1050 }; 1051 1052 /* 1053 * This replaces auth-pam.c 1054 */ 1055 void 1056 start_pam(struct ssh *ssh) 1057 { 1058 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1059 1060 if (!options.use_pam) 1061 fatal("PAM: initialisation requested when UsePAM=no"); 1062 1063 if (sshpam_init(ssh, authctxt) == -1) 1064 fatal("PAM: initialisation failed"); 1065 } 1066 1067 void 1068 finish_pam(void) 1069 { 1070 sshpam_cleanup(); 1071 } 1072 1073 1074 u_int 1075 do_pam_account(void) 1076 { 1077 debug("%s: called", __func__); 1078 if (sshpam_account_status != -1) 1079 return (sshpam_account_status); 1080 1081 expose_authinfo(__func__); 1082 1083 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1084 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1085 pam_strerror(sshpam_handle, sshpam_err)); 1086 1087 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1088 sshpam_account_status = 0; 1089 return (sshpam_account_status); 1090 } 1091 1092 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1093 sshpam_password_change_required(1); 1094 1095 sshpam_account_status = 1; 1096 return (sshpam_account_status); 1097 } 1098 1099 void 1100 do_pam_setcred(int init) 1101 { 1102 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1103 (const void *)&store_conv); 1104 if (sshpam_err != PAM_SUCCESS) 1105 fatal("PAM: failed to set PAM_CONV: %s", 1106 pam_strerror(sshpam_handle, sshpam_err)); 1107 if (init) { 1108 debug("PAM: establishing credentials"); 1109 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1110 } else { 1111 debug("PAM: reinitializing credentials"); 1112 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1113 } 1114 if (sshpam_err == PAM_SUCCESS) { 1115 sshpam_cred_established = 1; 1116 return; 1117 } 1118 if (sshpam_authenticated) 1119 fatal("PAM: pam_setcred(): %s", 1120 pam_strerror(sshpam_handle, sshpam_err)); 1121 else 1122 debug("PAM: pam_setcred(): %s", 1123 pam_strerror(sshpam_handle, sshpam_err)); 1124 } 1125 1126 static int 1127 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1128 struct pam_response **resp, void *data) 1129 { 1130 char input[PAM_MAX_MSG_SIZE]; 1131 struct pam_response *reply; 1132 int i; 1133 1134 debug3("PAM: %s called with %d messages", __func__, n); 1135 1136 *resp = NULL; 1137 1138 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1139 return (PAM_CONV_ERR); 1140 1141 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1142 return (PAM_CONV_ERR); 1143 1144 for (i = 0; i < n; ++i) { 1145 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1146 case PAM_PROMPT_ECHO_OFF: 1147 reply[i].resp = 1148 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1149 RP_ALLOW_STDIN); 1150 reply[i].resp_retcode = PAM_SUCCESS; 1151 break; 1152 case PAM_PROMPT_ECHO_ON: 1153 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1154 if (fgets(input, sizeof input, stdin) == NULL) 1155 input[0] = '\0'; 1156 if ((reply[i].resp = strdup(input)) == NULL) 1157 goto fail; 1158 reply[i].resp_retcode = PAM_SUCCESS; 1159 break; 1160 case PAM_ERROR_MSG: 1161 case PAM_TEXT_INFO: 1162 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1163 reply[i].resp_retcode = PAM_SUCCESS; 1164 break; 1165 default: 1166 goto fail; 1167 } 1168 } 1169 *resp = reply; 1170 return (PAM_SUCCESS); 1171 1172 fail: 1173 for(i = 0; i < n; i++) { 1174 free(reply[i].resp); 1175 } 1176 free(reply); 1177 return (PAM_CONV_ERR); 1178 } 1179 1180 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1181 1182 /* 1183 * XXX this should be done in the authentication phase, but ssh1 doesn't 1184 * support that 1185 */ 1186 void 1187 do_pam_chauthtok(void) 1188 { 1189 if (use_privsep) 1190 fatal("Password expired (unable to change with privsep)"); 1191 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1192 (const void *)&tty_conv); 1193 if (sshpam_err != PAM_SUCCESS) 1194 fatal("PAM: failed to set PAM_CONV: %s", 1195 pam_strerror(sshpam_handle, sshpam_err)); 1196 debug("PAM: changing password"); 1197 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1198 if (sshpam_err != PAM_SUCCESS) 1199 fatal("PAM: pam_chauthtok(): %s", 1200 pam_strerror(sshpam_handle, sshpam_err)); 1201 } 1202 1203 void 1204 do_pam_session(struct ssh *ssh) 1205 { 1206 debug3("PAM: opening session"); 1207 1208 expose_authinfo(__func__); 1209 1210 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1211 (const void *)&store_conv); 1212 if (sshpam_err != PAM_SUCCESS) 1213 fatal("PAM: failed to set PAM_CONV: %s", 1214 pam_strerror(sshpam_handle, sshpam_err)); 1215 sshpam_err = pam_open_session(sshpam_handle, 0); 1216 if (sshpam_err == PAM_SUCCESS) 1217 sshpam_session_open = 1; 1218 else { 1219 sshpam_session_open = 0; 1220 auth_restrict_session(ssh); 1221 error("PAM: pam_open_session(): %s", 1222 pam_strerror(sshpam_handle, sshpam_err)); 1223 } 1224 1225 } 1226 1227 int 1228 is_pam_session_open(void) 1229 { 1230 return sshpam_session_open; 1231 } 1232 1233 /* 1234 * Set a PAM environment string. We need to do this so that the session 1235 * modules can handle things like Kerberos/GSI credentials that appear 1236 * during the ssh authentication process. 1237 */ 1238 int 1239 do_pam_putenv(char *name, char *value) 1240 { 1241 int ret = 1; 1242 char *compound; 1243 size_t len; 1244 1245 len = strlen(name) + strlen(value) + 2; 1246 compound = xmalloc(len); 1247 1248 snprintf(compound, len, "%s=%s", name, value); 1249 ret = pam_putenv(sshpam_handle, compound); 1250 free(compound); 1251 1252 return (ret); 1253 } 1254 1255 char ** 1256 fetch_pam_child_environment(void) 1257 { 1258 return sshpam_env; 1259 } 1260 1261 char ** 1262 fetch_pam_environment(void) 1263 { 1264 return (pam_getenvlist(sshpam_handle)); 1265 } 1266 1267 void 1268 free_pam_environment(char **env) 1269 { 1270 char **envp; 1271 1272 if (env == NULL) 1273 return; 1274 1275 for (envp = env; *envp; envp++) 1276 free(*envp); 1277 free(env); 1278 } 1279 1280 /* 1281 * "Blind" conversation function for password authentication. Assumes that 1282 * echo-off prompts are for the password and stores messages for later 1283 * display. 1284 */ 1285 static int 1286 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1287 struct pam_response **resp, void *data) 1288 { 1289 struct pam_response *reply; 1290 int r, i; 1291 size_t len; 1292 1293 debug3("PAM: %s called with %d messages", __func__, n); 1294 1295 *resp = NULL; 1296 1297 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1298 return (PAM_CONV_ERR); 1299 1300 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1301 return (PAM_CONV_ERR); 1302 1303 for (i = 0; i < n; ++i) { 1304 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1305 case PAM_PROMPT_ECHO_OFF: 1306 if (sshpam_password == NULL) 1307 goto fail; 1308 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1309 goto fail; 1310 reply[i].resp_retcode = PAM_SUCCESS; 1311 break; 1312 case PAM_ERROR_MSG: 1313 case PAM_TEXT_INFO: 1314 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1315 if (len > 0) { 1316 if ((r = sshbuf_putf(loginmsg, "%s\n", 1317 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1318 fatal("%s: buffer error: %s", 1319 __func__, ssh_err(r)); 1320 } 1321 if ((reply[i].resp = strdup("")) == NULL) 1322 goto fail; 1323 reply[i].resp_retcode = PAM_SUCCESS; 1324 break; 1325 default: 1326 goto fail; 1327 } 1328 } 1329 *resp = reply; 1330 return (PAM_SUCCESS); 1331 1332 fail: 1333 for(i = 0; i < n; i++) { 1334 free(reply[i].resp); 1335 } 1336 free(reply); 1337 return (PAM_CONV_ERR); 1338 } 1339 1340 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1341 1342 /* 1343 * Attempt password authentication via PAM 1344 */ 1345 int 1346 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1347 { 1348 int flags = (options.permit_empty_passwd == 0 ? 1349 PAM_DISALLOW_NULL_AUTHTOK : 0); 1350 char *fake = NULL; 1351 1352 if (!options.use_pam || sshpam_handle == NULL) 1353 fatal("PAM: %s called when PAM disabled or failed to " 1354 "initialise.", __func__); 1355 1356 sshpam_password = password; 1357 sshpam_authctxt = authctxt; 1358 1359 /* 1360 * If the user logging in is invalid, or is root but is not permitted 1361 * by PermitRootLogin, use an invalid password to prevent leaking 1362 * information via timing (eg if the PAM config has a delay on fail). 1363 */ 1364 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1365 options.permit_root_login != PERMIT_YES)) 1366 sshpam_password = fake = fake_password(password); 1367 1368 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1369 (const void *)&passwd_conv); 1370 if (sshpam_err != PAM_SUCCESS) 1371 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1372 pam_strerror(sshpam_handle, sshpam_err)); 1373 1374 sshpam_err = pam_authenticate(sshpam_handle, flags); 1375 sshpam_password = NULL; 1376 free(fake); 1377 if (sshpam_err == PAM_MAXTRIES) 1378 sshpam_set_maxtries_reached(1); 1379 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1380 debug("PAM: password authentication accepted for %.100s", 1381 authctxt->user); 1382 return 1; 1383 } else { 1384 debug("PAM: password authentication failed for %.100s: %s", 1385 authctxt->valid ? authctxt->user : "an illegal user", 1386 pam_strerror(sshpam_handle, sshpam_err)); 1387 return 0; 1388 } 1389 } 1390 1391 int 1392 sshpam_get_maxtries_reached(void) 1393 { 1394 return sshpam_maxtries_reached; 1395 } 1396 1397 void 1398 sshpam_set_maxtries_reached(int reached) 1399 { 1400 if (reached == 0 || sshpam_maxtries_reached) 1401 return; 1402 sshpam_maxtries_reached = 1; 1403 options.password_authentication = 0; 1404 options.kbd_interactive_authentication = 0; 1405 } 1406 #endif /* USE_PAM */ 1407