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_f("received %u environment variables, expected <= 1024", 357 num_env); 358 } 359 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 360 debug3("PAM: num env strings %u", num_env); 361 for(i = 0; i < num_env; i++) { 362 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 363 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 364 } 365 sshpam_env[num_env] = NULL; 366 367 /* Import PAM environment from subprocess */ 368 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 369 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 370 if (num_env > 1024) { 371 fatal_f("received %u PAM env variables, expected <= 1024", 372 num_env); 373 } 374 debug("PAM: num PAM env strings %u", num_env); 375 for (i = 0; i < num_env; i++) { 376 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 377 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 378 /* Errors are not fatal here */ 379 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 380 error("PAM: pam_putenv: %s", 381 pam_strerror(sshpam_handle, r)); 382 } 383 /* 384 * XXX this possibly leaks env because it is not documented 385 * what pam_putenv() does with it. Does it copy it? Does it 386 * take ownweship? We don't know, so it's safest just to leak. 387 */ 388 } 389 #endif 390 } 391 392 /* 393 * Conversation function for authentication thread. 394 */ 395 static int 396 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 397 struct pam_response **resp, void *data) 398 { 399 struct sshbuf *buffer; 400 struct pam_ctxt *ctxt; 401 struct pam_response *reply; 402 int r, i; 403 u_char status; 404 405 debug3("PAM: %s entering, %d messages", __func__, n); 406 *resp = NULL; 407 408 if (data == NULL) { 409 error("PAM: conversation function passed a null context"); 410 return (PAM_CONV_ERR); 411 } 412 ctxt = data; 413 if (n <= 0 || n > PAM_MAX_NUM_MSG) 414 return (PAM_CONV_ERR); 415 416 if ((reply = calloc(n, sizeof(*reply))) == NULL) 417 return PAM_CONV_ERR; 418 if ((buffer = sshbuf_new()) == NULL) { 419 free(reply); 420 return PAM_CONV_ERR; 421 } 422 423 for (i = 0; i < n; ++i) { 424 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 425 case PAM_PROMPT_ECHO_OFF: 426 case PAM_PROMPT_ECHO_ON: 427 if ((r = sshbuf_put_cstring(buffer, 428 PAM_MSG_MEMBER(msg, i, msg))) != 0) 429 fatal("%s: buffer error: %s", 430 __func__, ssh_err(r)); 431 if (ssh_msg_send(ctxt->pam_csock, 432 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 433 goto fail; 434 435 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 436 goto fail; 437 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 438 fatal("%s: buffer error: %s", 439 __func__, ssh_err(r)); 440 if (status != PAM_AUTHTOK) 441 goto fail; 442 if ((r = sshbuf_get_cstring(buffer, 443 &reply[i].resp, NULL)) != 0) 444 fatal("%s: buffer error: %s", 445 __func__, ssh_err(r)); 446 break; 447 case PAM_ERROR_MSG: 448 case PAM_TEXT_INFO: 449 if ((r = sshbuf_put_cstring(buffer, 450 PAM_MSG_MEMBER(msg, i, msg))) != 0) 451 fatal("%s: buffer error: %s", 452 __func__, ssh_err(r)); 453 if (ssh_msg_send(ctxt->pam_csock, 454 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 455 goto fail; 456 break; 457 default: 458 goto fail; 459 } 460 sshbuf_reset(buffer); 461 } 462 sshbuf_free(buffer); 463 *resp = reply; 464 return (PAM_SUCCESS); 465 466 fail: 467 for(i = 0; i < n; i++) { 468 free(reply[i].resp); 469 } 470 free(reply); 471 sshbuf_free(buffer); 472 return (PAM_CONV_ERR); 473 } 474 475 /* 476 * Authentication thread. 477 */ 478 static void * 479 sshpam_thread(void *ctxtp) 480 { 481 struct pam_ctxt *ctxt = ctxtp; 482 struct sshbuf *buffer = NULL; 483 struct pam_conv sshpam_conv; 484 int r, flags = (options.permit_empty_passwd == 0 ? 485 PAM_DISALLOW_NULL_AUTHTOK : 0); 486 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 487 extern char **environ; 488 char **env_from_pam; 489 u_int i; 490 const char *pam_user; 491 const char **ptr_pam_user = &pam_user; 492 char *tz = getenv("TZ"); 493 494 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 495 (sshpam_const void **)ptr_pam_user); 496 if (sshpam_err != PAM_SUCCESS) 497 goto auth_fail; 498 499 environ[0] = NULL; 500 if (tz != NULL) 501 if (setenv("TZ", tz, 1) == -1) 502 error("PAM: could not set TZ environment: %s", 503 strerror(errno)); 504 505 if (sshpam_authctxt != NULL) { 506 setproctitle("%s [pam]", 507 sshpam_authctxt->valid ? pam_user : "unknown"); 508 } 509 #endif 510 511 sshpam_conv.conv = sshpam_thread_conv; 512 sshpam_conv.appdata_ptr = ctxt; 513 514 if (sshpam_authctxt == NULL) 515 fatal("%s: PAM authctxt not initialized", __func__); 516 517 if ((buffer = sshbuf_new()) == NULL) 518 fatal("%s: sshbuf_new failed", __func__); 519 520 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 521 (const void *)&sshpam_conv); 522 if (sshpam_err != PAM_SUCCESS) 523 goto auth_fail; 524 sshpam_err = pam_authenticate(sshpam_handle, flags); 525 if (sshpam_err == PAM_MAXTRIES) 526 sshpam_set_maxtries_reached(1); 527 if (sshpam_err != PAM_SUCCESS) 528 goto auth_fail; 529 530 if (!do_pam_account()) { 531 sshpam_err = PAM_ACCT_EXPIRED; 532 goto auth_fail; 533 } 534 if (sshpam_authctxt->force_pwchange) { 535 sshpam_err = pam_chauthtok(sshpam_handle, 536 PAM_CHANGE_EXPIRED_AUTHTOK); 537 if (sshpam_err != PAM_SUCCESS) 538 goto auth_fail; 539 sshpam_password_change_required(0); 540 } 541 542 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 543 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 544 545 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 546 /* Export variables set by do_pam_account */ 547 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 548 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 549 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 550 551 /* Export any environment strings set in child */ 552 for (i = 0; environ[i] != NULL; i++) { 553 /* Count */ 554 if (i > INT_MAX) 555 fatal("%s: too many environment strings", __func__); 556 } 557 if ((r = sshbuf_put_u32(buffer, i)) != 0) 558 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 559 for (i = 0; environ[i] != NULL; i++) { 560 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 561 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 562 } 563 /* Export any environment strings set by PAM in child */ 564 env_from_pam = pam_getenvlist(sshpam_handle); 565 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 566 /* Count */ 567 if (i > INT_MAX) 568 fatal("%s: too many PAM environment strings", __func__); 569 } 570 if ((r = sshbuf_put_u32(buffer, i)) != 0) 571 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 572 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 573 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 574 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 575 } 576 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 577 578 /* XXX - can't do much about an error here */ 579 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 580 sshbuf_free(buffer); 581 pthread_exit(NULL); 582 583 auth_fail: 584 if ((r = sshbuf_put_cstring(buffer, 585 pam_strerror(sshpam_handle, sshpam_err))) != 0) 586 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 587 /* XXX - can't do much about an error here */ 588 if (sshpam_err == PAM_ACCT_EXPIRED) 589 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 590 else if (sshpam_maxtries_reached) 591 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 592 else 593 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 594 sshbuf_free(buffer); 595 pthread_exit(NULL); 596 597 return (NULL); /* Avoid warning for non-pthread case */ 598 } 599 600 void 601 sshpam_thread_cleanup(void) 602 { 603 struct pam_ctxt *ctxt = cleanup_ctxt; 604 605 debug3("PAM: %s entering", __func__); 606 if (ctxt != NULL && ctxt->pam_thread != 0) { 607 pthread_cancel(ctxt->pam_thread); 608 pthread_join(ctxt->pam_thread, NULL); 609 close(ctxt->pam_psock); 610 close(ctxt->pam_csock); 611 memset(ctxt, 0, sizeof(*ctxt)); 612 cleanup_ctxt = NULL; 613 } 614 } 615 616 static int 617 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 618 struct pam_response **resp, void *data) 619 { 620 debug3("PAM: %s entering, %d messages", __func__, n); 621 return (PAM_CONV_ERR); 622 } 623 624 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 625 626 static int 627 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 628 struct pam_response **resp, void *data) 629 { 630 struct pam_response *reply; 631 int r, i; 632 633 debug3("PAM: %s called with %d messages", __func__, n); 634 *resp = NULL; 635 636 if (n <= 0 || n > PAM_MAX_NUM_MSG) 637 return (PAM_CONV_ERR); 638 639 if ((reply = calloc(n, sizeof(*reply))) == NULL) 640 return (PAM_CONV_ERR); 641 642 for (i = 0; i < n; ++i) { 643 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 644 case PAM_ERROR_MSG: 645 case PAM_TEXT_INFO: 646 if ((r = sshbuf_putf(loginmsg, "%s\n", 647 PAM_MSG_MEMBER(msg, i, msg))) != 0) 648 fatal("%s: buffer error: %s", 649 __func__, ssh_err(r)); 650 reply[i].resp_retcode = PAM_SUCCESS; 651 break; 652 default: 653 goto fail; 654 } 655 } 656 *resp = reply; 657 return (PAM_SUCCESS); 658 659 fail: 660 for(i = 0; i < n; i++) { 661 free(reply[i].resp); 662 } 663 free(reply); 664 return (PAM_CONV_ERR); 665 } 666 667 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 668 669 void 670 sshpam_cleanup(void) 671 { 672 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 673 return; 674 debug("PAM: cleanup"); 675 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 676 if (sshpam_session_open) { 677 debug("PAM: closing session"); 678 pam_close_session(sshpam_handle, PAM_SILENT); 679 sshpam_session_open = 0; 680 } 681 if (sshpam_cred_established) { 682 debug("PAM: deleting credentials"); 683 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 684 sshpam_cred_established = 0; 685 } 686 sshpam_authenticated = 0; 687 pam_end(sshpam_handle, sshpam_err); 688 sshpam_handle = NULL; 689 } 690 691 static int 692 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 693 { 694 const char *pam_user, *user = authctxt->user; 695 const char **ptr_pam_user = &pam_user; 696 int r; 697 698 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 699 /* Protect buggy PAM implementations from excessively long usernames */ 700 if (strlen(user) >= PAM_MAX_RESP_SIZE) 701 fatal("Username too long from %s port %d", 702 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 703 #endif 704 if (sshpam_handle == NULL) { 705 if (ssh == NULL) { 706 fatal("%s: called initially with no " 707 "packet context", __func__); 708 } 709 } if (sshpam_handle != NULL) { 710 /* We already have a PAM context; check if the user matches */ 711 sshpam_err = pam_get_item(sshpam_handle, 712 PAM_USER, (sshpam_const void **)ptr_pam_user); 713 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 714 return (0); 715 pam_end(sshpam_handle, sshpam_err); 716 sshpam_handle = NULL; 717 } 718 debug("PAM: initializing for \"%s\"", user); 719 sshpam_err = 720 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 721 sshpam_authctxt = authctxt; 722 723 if (sshpam_err != PAM_SUCCESS) { 724 pam_end(sshpam_handle, sshpam_err); 725 sshpam_handle = NULL; 726 return (-1); 727 } 728 729 if (ssh != NULL && sshpam_rhost == NULL) { 730 /* 731 * We need to cache these as we don't have packet context 732 * during the kbdint flow. 733 */ 734 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 735 options.use_dns)); 736 sshpam_laddr = get_local_ipaddr( 737 ssh_packet_get_connection_in(ssh)); 738 } 739 if (sshpam_rhost != NULL) { 740 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 741 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 742 sshpam_rhost); 743 if (sshpam_err != PAM_SUCCESS) { 744 pam_end(sshpam_handle, sshpam_err); 745 sshpam_handle = NULL; 746 return (-1); 747 } 748 } 749 if (ssh != NULL && sshpam_laddr != NULL) { 750 char *conninfo; 751 752 /* Put SSH_CONNECTION in the PAM environment too */ 753 xasprintf(&conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 754 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 755 sshpam_laddr, ssh_local_port(ssh)); 756 if ((r = pam_putenv(sshpam_handle, conninfo)) != PAM_SUCCESS) 757 logit("pam_putenv: %s", pam_strerror(sshpam_handle, r)); 758 free(conninfo); 759 } 760 761 #ifdef PAM_TTY_KLUDGE 762 /* 763 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 764 * sshd doesn't set the tty until too late in the auth process and 765 * may not even set one (for tty-less connections) 766 */ 767 debug("PAM: setting PAM_TTY to \"ssh\""); 768 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 769 if (sshpam_err != PAM_SUCCESS) { 770 pam_end(sshpam_handle, sshpam_err); 771 sshpam_handle = NULL; 772 return (-1); 773 } 774 #endif 775 return (0); 776 } 777 778 static void 779 expose_authinfo(const char *caller) 780 { 781 char *auth_info; 782 783 /* 784 * Expose authentication information to PAM. 785 * The environment variable is versioned. Please increment the 786 * version suffix if the format of session_info changes. 787 */ 788 if (sshpam_authctxt->session_info == NULL) 789 auth_info = xstrdup(""); 790 else if ((auth_info = sshbuf_dup_string( 791 sshpam_authctxt->session_info)) == NULL) 792 fatal("%s: sshbuf_dup_string failed", __func__); 793 794 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 795 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 796 free(auth_info); 797 } 798 799 static void * 800 sshpam_init_ctx(Authctxt *authctxt) 801 { 802 struct pam_ctxt *ctxt; 803 int result, socks[2]; 804 805 debug3("PAM: %s entering", __func__); 806 /* 807 * Refuse to start if we don't have PAM enabled or do_pam_account 808 * has previously failed. 809 */ 810 if (!options.use_pam || sshpam_account_status == 0) 811 return NULL; 812 813 /* Initialize PAM */ 814 if (sshpam_init(NULL, authctxt) == -1) { 815 error("PAM: initialization failed"); 816 return (NULL); 817 } 818 819 expose_authinfo(__func__); 820 ctxt = xcalloc(1, sizeof *ctxt); 821 822 /* Start the authentication thread */ 823 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 824 error("PAM: failed create sockets: %s", strerror(errno)); 825 free(ctxt); 826 return (NULL); 827 } 828 ctxt->pam_psock = socks[0]; 829 ctxt->pam_csock = socks[1]; 830 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 831 if (result != 0) { 832 error("PAM: failed to start authentication thread: %s", 833 strerror(result)); 834 close(socks[0]); 835 close(socks[1]); 836 free(ctxt); 837 return (NULL); 838 } 839 cleanup_ctxt = ctxt; 840 return (ctxt); 841 } 842 843 static int 844 sshpam_query(void *ctx, char **name, char **info, 845 u_int *num, char ***prompts, u_int **echo_on) 846 { 847 struct sshbuf *buffer; 848 struct pam_ctxt *ctxt = ctx; 849 size_t plen; 850 u_char type; 851 char *msg; 852 size_t len, mlen; 853 int r; 854 855 debug3("PAM: %s entering", __func__); 856 if ((buffer = sshbuf_new()) == NULL) 857 fatal("%s: sshbuf_new failed", __func__); 858 *name = xstrdup(""); 859 *info = xstrdup(""); 860 *prompts = xmalloc(sizeof(char *)); 861 **prompts = NULL; 862 plen = 0; 863 *echo_on = xmalloc(sizeof(u_int)); 864 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 865 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 866 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 867 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 868 switch (type) { 869 case PAM_PROMPT_ECHO_ON: 870 case PAM_PROMPT_ECHO_OFF: 871 *num = 1; 872 len = plen + mlen + 1; 873 **prompts = xreallocarray(**prompts, 1, len); 874 strlcpy(**prompts + plen, msg, len - plen); 875 plen += mlen; 876 **echo_on = (type == PAM_PROMPT_ECHO_ON); 877 free(msg); 878 sshbuf_free(buffer); 879 return (0); 880 case PAM_ERROR_MSG: 881 case PAM_TEXT_INFO: 882 /* accumulate messages */ 883 len = plen + mlen + 2; 884 **prompts = xreallocarray(**prompts, 1, len); 885 strlcpy(**prompts + plen, msg, len - plen); 886 plen += mlen; 887 strlcat(**prompts + plen, "\n", len - plen); 888 plen++; 889 free(msg); 890 break; 891 case PAM_ACCT_EXPIRED: 892 case PAM_MAXTRIES: 893 if (type == PAM_ACCT_EXPIRED) 894 sshpam_account_status = 0; 895 if (type == PAM_MAXTRIES) 896 sshpam_set_maxtries_reached(1); 897 /* FALLTHROUGH */ 898 case PAM_AUTH_ERR: 899 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 900 if (**prompts != NULL && strlen(**prompts) != 0) { 901 free(*info); 902 *info = **prompts; 903 **prompts = NULL; 904 *num = 0; 905 **echo_on = 0; 906 ctxt->pam_done = -1; 907 free(msg); 908 sshbuf_free(buffer); 909 return 0; 910 } 911 /* FALLTHROUGH */ 912 case PAM_SUCCESS: 913 if (**prompts != NULL) { 914 /* drain any accumulated messages */ 915 debug("PAM: %s", **prompts); 916 if ((r = sshbuf_put(loginmsg, **prompts, 917 strlen(**prompts))) != 0) 918 fatal("%s: buffer error: %s", 919 __func__, ssh_err(r)); 920 free(**prompts); 921 **prompts = NULL; 922 } 923 if (type == PAM_SUCCESS) { 924 if (!sshpam_authctxt->valid || 925 (sshpam_authctxt->pw->pw_uid == 0 && 926 options.permit_root_login != PERMIT_YES)) 927 fatal("Internal error: PAM auth " 928 "succeeded when it should have " 929 "failed"); 930 import_environments(buffer); 931 *num = 0; 932 **echo_on = 0; 933 ctxt->pam_done = 1; 934 free(msg); 935 sshbuf_free(buffer); 936 return (0); 937 } 938 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER, 939 sshpam_authctxt->user); 940 error("PAM: %s for %s%.100s from %.100s", msg, 941 sshpam_authctxt->valid ? "" : "illegal user ", 942 sshpam_authctxt->user, sshpam_rhost); 943 /* FALLTHROUGH */ 944 default: 945 *num = 0; 946 **echo_on = 0; 947 free(msg); 948 ctxt->pam_done = -1; 949 sshbuf_free(buffer); 950 return (-1); 951 } 952 } 953 sshbuf_free(buffer); 954 return (-1); 955 } 956 957 /* 958 * Returns a junk password of identical length to that the user supplied. 959 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 960 * vary processing time in proportion to password length. 961 */ 962 static char * 963 fake_password(const char *wire_password) 964 { 965 const char junk[] = "\b\n\r\177INCORRECT"; 966 char *ret = NULL; 967 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 968 969 if (l >= INT_MAX) 970 fatal("%s: password length too long: %zu", __func__, l); 971 972 ret = malloc(l + 1); 973 if (ret == NULL) 974 return NULL; 975 for (i = 0; i < l; i++) 976 ret[i] = junk[i % (sizeof(junk) - 1)]; 977 ret[i] = '\0'; 978 return ret; 979 } 980 981 /* XXX - see also comment in auth-chall.c:verify_response */ 982 static int 983 sshpam_respond(void *ctx, u_int num, char **resp) 984 { 985 struct sshbuf *buffer; 986 struct pam_ctxt *ctxt = ctx; 987 char *fake; 988 int r; 989 990 debug2("PAM: %s entering, %u responses", __func__, num); 991 switch (ctxt->pam_done) { 992 case 1: 993 sshpam_authenticated = 1; 994 return (0); 995 case 0: 996 break; 997 default: 998 return (-1); 999 } 1000 if (num != 1) { 1001 error("PAM: expected one response, got %u", num); 1002 return (-1); 1003 } 1004 if ((buffer = sshbuf_new()) == NULL) 1005 fatal("%s: sshbuf_new failed", __func__); 1006 if (sshpam_authctxt->valid && 1007 (sshpam_authctxt->pw->pw_uid != 0 || 1008 options.permit_root_login == PERMIT_YES)) { 1009 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 1010 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1011 } else { 1012 fake = fake_password(*resp); 1013 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1014 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1015 free(fake); 1016 } 1017 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1018 sshbuf_free(buffer); 1019 return (-1); 1020 } 1021 sshbuf_free(buffer); 1022 return (1); 1023 } 1024 1025 static void 1026 sshpam_free_ctx(void *ctxtp) 1027 { 1028 struct pam_ctxt *ctxt = ctxtp; 1029 1030 debug3("PAM: %s entering", __func__); 1031 sshpam_thread_cleanup(); 1032 free(ctxt); 1033 /* 1034 * We don't call sshpam_cleanup() here because we may need the PAM 1035 * handle at a later stage, e.g. when setting up a session. It's 1036 * still on the cleanup list, so pam_end() *will* be called before 1037 * the server process terminates. 1038 */ 1039 } 1040 1041 KbdintDevice sshpam_device = { 1042 "pam", 1043 sshpam_init_ctx, 1044 sshpam_query, 1045 sshpam_respond, 1046 sshpam_free_ctx 1047 }; 1048 1049 KbdintDevice mm_sshpam_device = { 1050 "pam", 1051 mm_sshpam_init_ctx, 1052 mm_sshpam_query, 1053 mm_sshpam_respond, 1054 mm_sshpam_free_ctx 1055 }; 1056 1057 /* 1058 * This replaces auth-pam.c 1059 */ 1060 void 1061 start_pam(struct ssh *ssh) 1062 { 1063 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1064 1065 if (!options.use_pam) 1066 fatal("PAM: initialisation requested when UsePAM=no"); 1067 1068 if (sshpam_init(ssh, authctxt) == -1) 1069 fatal("PAM: initialisation failed"); 1070 } 1071 1072 void 1073 finish_pam(void) 1074 { 1075 sshpam_cleanup(); 1076 } 1077 1078 1079 u_int 1080 do_pam_account(void) 1081 { 1082 debug("%s: called", __func__); 1083 if (sshpam_account_status != -1) 1084 return (sshpam_account_status); 1085 1086 expose_authinfo(__func__); 1087 1088 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1089 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1090 pam_strerror(sshpam_handle, sshpam_err)); 1091 1092 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1093 sshpam_account_status = 0; 1094 return (sshpam_account_status); 1095 } 1096 1097 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1098 sshpam_password_change_required(1); 1099 1100 sshpam_account_status = 1; 1101 return (sshpam_account_status); 1102 } 1103 1104 void 1105 do_pam_setcred(int init) 1106 { 1107 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1108 (const void *)&store_conv); 1109 if (sshpam_err != PAM_SUCCESS) 1110 fatal("PAM: failed to set PAM_CONV: %s", 1111 pam_strerror(sshpam_handle, sshpam_err)); 1112 if (init) { 1113 debug("PAM: establishing credentials"); 1114 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1115 } else { 1116 debug("PAM: reinitializing credentials"); 1117 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1118 } 1119 if (sshpam_err == PAM_SUCCESS) { 1120 sshpam_cred_established = 1; 1121 return; 1122 } 1123 if (sshpam_authenticated) 1124 fatal("PAM: pam_setcred(): %s", 1125 pam_strerror(sshpam_handle, sshpam_err)); 1126 else 1127 debug("PAM: pam_setcred(): %s", 1128 pam_strerror(sshpam_handle, sshpam_err)); 1129 } 1130 1131 static int 1132 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1133 struct pam_response **resp, void *data) 1134 { 1135 char input[PAM_MAX_MSG_SIZE]; 1136 struct pam_response *reply; 1137 int i; 1138 1139 debug3("PAM: %s called with %d messages", __func__, n); 1140 1141 *resp = NULL; 1142 1143 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1144 return (PAM_CONV_ERR); 1145 1146 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1147 return (PAM_CONV_ERR); 1148 1149 for (i = 0; i < n; ++i) { 1150 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1151 case PAM_PROMPT_ECHO_OFF: 1152 reply[i].resp = 1153 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1154 RP_ALLOW_STDIN); 1155 reply[i].resp_retcode = PAM_SUCCESS; 1156 break; 1157 case PAM_PROMPT_ECHO_ON: 1158 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1159 if (fgets(input, sizeof input, stdin) == NULL) 1160 input[0] = '\0'; 1161 if ((reply[i].resp = strdup(input)) == NULL) 1162 goto fail; 1163 reply[i].resp_retcode = PAM_SUCCESS; 1164 break; 1165 case PAM_ERROR_MSG: 1166 case PAM_TEXT_INFO: 1167 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1168 reply[i].resp_retcode = PAM_SUCCESS; 1169 break; 1170 default: 1171 goto fail; 1172 } 1173 } 1174 *resp = reply; 1175 return (PAM_SUCCESS); 1176 1177 fail: 1178 for(i = 0; i < n; i++) { 1179 free(reply[i].resp); 1180 } 1181 free(reply); 1182 return (PAM_CONV_ERR); 1183 } 1184 1185 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1186 1187 /* 1188 * XXX this should be done in the authentication phase, but ssh1 doesn't 1189 * support that 1190 */ 1191 void 1192 do_pam_chauthtok(void) 1193 { 1194 if (use_privsep) 1195 fatal("Password expired (unable to change with privsep)"); 1196 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1197 (const void *)&tty_conv); 1198 if (sshpam_err != PAM_SUCCESS) 1199 fatal("PAM: failed to set PAM_CONV: %s", 1200 pam_strerror(sshpam_handle, sshpam_err)); 1201 debug("PAM: changing password"); 1202 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1203 if (sshpam_err != PAM_SUCCESS) 1204 fatal("PAM: pam_chauthtok(): %s", 1205 pam_strerror(sshpam_handle, sshpam_err)); 1206 } 1207 1208 void 1209 do_pam_session(struct ssh *ssh) 1210 { 1211 debug3("PAM: opening session"); 1212 1213 expose_authinfo(__func__); 1214 1215 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1216 (const void *)&store_conv); 1217 if (sshpam_err != PAM_SUCCESS) 1218 fatal("PAM: failed to set PAM_CONV: %s", 1219 pam_strerror(sshpam_handle, sshpam_err)); 1220 sshpam_err = pam_open_session(sshpam_handle, 0); 1221 if (sshpam_err == PAM_SUCCESS) 1222 sshpam_session_open = 1; 1223 else { 1224 sshpam_session_open = 0; 1225 auth_restrict_session(ssh); 1226 error("PAM: pam_open_session(): %s", 1227 pam_strerror(sshpam_handle, sshpam_err)); 1228 } 1229 1230 } 1231 1232 int 1233 is_pam_session_open(void) 1234 { 1235 return sshpam_session_open; 1236 } 1237 1238 /* 1239 * Set a PAM environment string. We need to do this so that the session 1240 * modules can handle things like Kerberos/GSI credentials that appear 1241 * during the ssh authentication process. 1242 */ 1243 int 1244 do_pam_putenv(char *name, char *value) 1245 { 1246 int ret = 1; 1247 char *compound; 1248 size_t len; 1249 1250 len = strlen(name) + strlen(value) + 2; 1251 compound = xmalloc(len); 1252 1253 snprintf(compound, len, "%s=%s", name, value); 1254 ret = pam_putenv(sshpam_handle, compound); 1255 free(compound); 1256 1257 return (ret); 1258 } 1259 1260 char ** 1261 fetch_pam_child_environment(void) 1262 { 1263 return sshpam_env; 1264 } 1265 1266 char ** 1267 fetch_pam_environment(void) 1268 { 1269 return (pam_getenvlist(sshpam_handle)); 1270 } 1271 1272 void 1273 free_pam_environment(char **env) 1274 { 1275 char **envp; 1276 1277 if (env == NULL) 1278 return; 1279 1280 for (envp = env; *envp; envp++) 1281 free(*envp); 1282 free(env); 1283 } 1284 1285 /* 1286 * "Blind" conversation function for password authentication. Assumes that 1287 * echo-off prompts are for the password and stores messages for later 1288 * display. 1289 */ 1290 static int 1291 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1292 struct pam_response **resp, void *data) 1293 { 1294 struct pam_response *reply; 1295 int r, i; 1296 size_t len; 1297 1298 debug3("PAM: %s called with %d messages", __func__, n); 1299 1300 *resp = NULL; 1301 1302 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1303 return (PAM_CONV_ERR); 1304 1305 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1306 return (PAM_CONV_ERR); 1307 1308 for (i = 0; i < n; ++i) { 1309 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1310 case PAM_PROMPT_ECHO_OFF: 1311 if (sshpam_password == NULL) 1312 goto fail; 1313 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1314 goto fail; 1315 reply[i].resp_retcode = PAM_SUCCESS; 1316 break; 1317 case PAM_ERROR_MSG: 1318 case PAM_TEXT_INFO: 1319 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1320 if (len > 0) { 1321 if ((r = sshbuf_putf(loginmsg, "%s\n", 1322 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1323 fatal("%s: buffer error: %s", 1324 __func__, ssh_err(r)); 1325 } 1326 if ((reply[i].resp = strdup("")) == NULL) 1327 goto fail; 1328 reply[i].resp_retcode = PAM_SUCCESS; 1329 break; 1330 default: 1331 goto fail; 1332 } 1333 } 1334 *resp = reply; 1335 return (PAM_SUCCESS); 1336 1337 fail: 1338 for(i = 0; i < n; i++) { 1339 free(reply[i].resp); 1340 } 1341 free(reply); 1342 return (PAM_CONV_ERR); 1343 } 1344 1345 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1346 1347 /* 1348 * Attempt password authentication via PAM 1349 */ 1350 int 1351 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1352 { 1353 int flags = (options.permit_empty_passwd == 0 ? 1354 PAM_DISALLOW_NULL_AUTHTOK : 0); 1355 char *fake = NULL; 1356 1357 if (!options.use_pam || sshpam_handle == NULL) 1358 fatal("PAM: %s called when PAM disabled or failed to " 1359 "initialise.", __func__); 1360 1361 sshpam_password = password; 1362 sshpam_authctxt = authctxt; 1363 1364 /* 1365 * If the user logging in is invalid, or is root but is not permitted 1366 * by PermitRootLogin, use an invalid password to prevent leaking 1367 * information via timing (eg if the PAM config has a delay on fail). 1368 */ 1369 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1370 options.permit_root_login != PERMIT_YES)) 1371 sshpam_password = fake = fake_password(password); 1372 1373 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1374 (const void *)&passwd_conv); 1375 if (sshpam_err != PAM_SUCCESS) 1376 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1377 pam_strerror(sshpam_handle, sshpam_err)); 1378 1379 sshpam_err = pam_authenticate(sshpam_handle, flags); 1380 sshpam_password = NULL; 1381 free(fake); 1382 if (sshpam_err == PAM_MAXTRIES) 1383 sshpam_set_maxtries_reached(1); 1384 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1385 debug("PAM: password authentication accepted for %.100s", 1386 authctxt->user); 1387 return 1; 1388 } else { 1389 debug("PAM: password authentication failed for %.100s: %s", 1390 authctxt->valid ? authctxt->user : "an illegal user", 1391 pam_strerror(sshpam_handle, sshpam_err)); 1392 return 0; 1393 } 1394 } 1395 1396 int 1397 sshpam_get_maxtries_reached(void) 1398 { 1399 return sshpam_maxtries_reached; 1400 } 1401 1402 void 1403 sshpam_set_maxtries_reached(int reached) 1404 { 1405 if (reached == 0 || sshpam_maxtries_reached) 1406 return; 1407 sshpam_maxtries_reached = 1; 1408 options.password_authentication = 0; 1409 options.kbd_interactive_authentication = 0; 1410 } 1411 #endif /* USE_PAM */ 1412