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" 108 109 extern ServerOptions options; 110 extern struct sshbuf *loginmsg; 111 extern u_int utmp_len; 112 113 /* so we don't silently change behaviour */ 114 #ifdef USE_POSIX_THREADS 115 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 116 #endif 117 118 /* 119 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 120 * and generally a bad idea. Use at own risk and do not expect support if 121 * this breaks. 122 */ 123 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 124 #include <pthread.h> 125 /* 126 * Avoid namespace clash when *not* using pthreads for systems *with* 127 * pthreads, which unconditionally define pthread_t via sys/types.h 128 * (e.g. Linux) 129 */ 130 typedef pthread_t sp_pthread_t; 131 #else 132 typedef pid_t sp_pthread_t; 133 #define pthread_exit fake_pthread_exit 134 #define pthread_create fake_pthread_create 135 #define pthread_cancel fake_pthread_cancel 136 #define pthread_join fake_pthread_join 137 #endif 138 139 struct pam_ctxt { 140 sp_pthread_t pam_thread; 141 int pam_psock; 142 int pam_csock; 143 int pam_done; 144 }; 145 146 static void sshpam_free_ctx(void *); 147 static struct pam_ctxt *cleanup_ctxt; 148 149 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 150 /* 151 * Simulate threads with processes. 152 */ 153 154 static int sshpam_thread_status = -1; 155 static sshsig_t sshpam_oldsig; 156 157 static void 158 sshpam_sigchld_handler(int sig) 159 { 160 ssh_signal(SIGCHLD, SIG_DFL); 161 if (cleanup_ctxt == NULL) 162 return; /* handler called after PAM cleanup, shouldn't happen */ 163 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 164 <= 0) { 165 /* PAM thread has not exitted, privsep slave must have */ 166 kill(cleanup_ctxt->pam_thread, SIGTERM); 167 while (waitpid(cleanup_ctxt->pam_thread, 168 &sshpam_thread_status, 0) == -1) { 169 if (errno == EINTR) 170 continue; 171 return; 172 } 173 } 174 if (WIFSIGNALED(sshpam_thread_status) && 175 WTERMSIG(sshpam_thread_status) == SIGTERM) 176 return; /* terminated by pthread_cancel */ 177 if (!WIFEXITED(sshpam_thread_status)) 178 sigdie("PAM: authentication thread exited unexpectedly"); 179 if (WEXITSTATUS(sshpam_thread_status) != 0) 180 sigdie("PAM: authentication thread exited uncleanly"); 181 } 182 183 /* ARGSUSED */ 184 static void 185 pthread_exit(void *value) 186 { 187 _exit(0); 188 } 189 190 /* ARGSUSED */ 191 static int 192 pthread_create(sp_pthread_t *thread, const void *attr, 193 void *(*thread_start)(void *), void *arg) 194 { 195 pid_t pid; 196 struct pam_ctxt *ctx = arg; 197 198 sshpam_thread_status = -1; 199 switch ((pid = fork())) { 200 case -1: 201 error("fork(): %s", strerror(errno)); 202 return errno; 203 case 0: 204 close(ctx->pam_psock); 205 ctx->pam_psock = -1; 206 thread_start(arg); 207 _exit(1); 208 default: 209 *thread = pid; 210 close(ctx->pam_csock); 211 ctx->pam_csock = -1; 212 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler); 213 return (0); 214 } 215 } 216 217 static int 218 pthread_cancel(sp_pthread_t thread) 219 { 220 ssh_signal(SIGCHLD, sshpam_oldsig); 221 return (kill(thread, SIGTERM)); 222 } 223 224 /* ARGSUSED */ 225 static int 226 pthread_join(sp_pthread_t thread, void **value) 227 { 228 int status; 229 230 if (sshpam_thread_status != -1) 231 return (sshpam_thread_status); 232 ssh_signal(SIGCHLD, sshpam_oldsig); 233 while (waitpid(thread, &status, 0) == -1) { 234 if (errno == EINTR) 235 continue; 236 fatal("%s: waitpid: %s", __func__, strerror(errno)); 237 } 238 return (status); 239 } 240 #endif 241 242 243 static pam_handle_t *sshpam_handle = NULL; 244 static int sshpam_err = 0; 245 static int sshpam_authenticated = 0; 246 static int sshpam_session_open = 0; 247 static int sshpam_cred_established = 0; 248 static int sshpam_account_status = -1; 249 static int sshpam_maxtries_reached = 0; 250 static char **sshpam_env = NULL; 251 static Authctxt *sshpam_authctxt = NULL; 252 static const char *sshpam_password = NULL; 253 static char *sshpam_rhost = NULL; 254 static char *sshpam_laddr = NULL; 255 static char *sshpam_conninfo = 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 /* XXX leak env? */ 379 } 380 #endif 381 } 382 383 /* 384 * Conversation function for authentication thread. 385 */ 386 static int 387 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 388 struct pam_response **resp, void *data) 389 { 390 struct sshbuf *buffer; 391 struct pam_ctxt *ctxt; 392 struct pam_response *reply; 393 int r, i; 394 u_char status; 395 396 debug3("PAM: %s entering, %d messages", __func__, n); 397 *resp = NULL; 398 399 if (data == NULL) { 400 error("PAM: conversation function passed a null context"); 401 return (PAM_CONV_ERR); 402 } 403 ctxt = data; 404 if (n <= 0 || n > PAM_MAX_NUM_MSG) 405 return (PAM_CONV_ERR); 406 407 if ((reply = calloc(n, sizeof(*reply))) == NULL) 408 return PAM_CONV_ERR; 409 if ((buffer = sshbuf_new()) == NULL) { 410 free(reply); 411 return PAM_CONV_ERR; 412 } 413 414 for (i = 0; i < n; ++i) { 415 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 416 case PAM_PROMPT_ECHO_OFF: 417 case PAM_PROMPT_ECHO_ON: 418 if ((r = sshbuf_put_cstring(buffer, 419 PAM_MSG_MEMBER(msg, i, msg))) != 0) 420 fatal("%s: buffer error: %s", 421 __func__, ssh_err(r)); 422 if (ssh_msg_send(ctxt->pam_csock, 423 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 424 goto fail; 425 426 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 427 goto fail; 428 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 429 fatal("%s: buffer error: %s", 430 __func__, ssh_err(r)); 431 if (status != PAM_AUTHTOK) 432 goto fail; 433 if ((r = sshbuf_get_cstring(buffer, 434 &reply[i].resp, NULL)) != 0) 435 fatal("%s: buffer error: %s", 436 __func__, ssh_err(r)); 437 break; 438 case PAM_ERROR_MSG: 439 case PAM_TEXT_INFO: 440 if ((r = sshbuf_put_cstring(buffer, 441 PAM_MSG_MEMBER(msg, i, msg))) != 0) 442 fatal("%s: buffer error: %s", 443 __func__, ssh_err(r)); 444 if (ssh_msg_send(ctxt->pam_csock, 445 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 446 goto fail; 447 break; 448 default: 449 goto fail; 450 } 451 sshbuf_reset(buffer); 452 } 453 sshbuf_free(buffer); 454 *resp = reply; 455 return (PAM_SUCCESS); 456 457 fail: 458 for(i = 0; i < n; i++) { 459 free(reply[i].resp); 460 } 461 free(reply); 462 sshbuf_free(buffer); 463 return (PAM_CONV_ERR); 464 } 465 466 /* 467 * Authentication thread. 468 */ 469 static void * 470 sshpam_thread(void *ctxtp) 471 { 472 struct pam_ctxt *ctxt = ctxtp; 473 struct sshbuf *buffer = NULL; 474 struct pam_conv sshpam_conv; 475 int r, flags = (options.permit_empty_passwd == 0 ? 476 PAM_DISALLOW_NULL_AUTHTOK : 0); 477 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 478 extern char **environ; 479 char **env_from_pam; 480 u_int i; 481 const char *pam_user; 482 const char **ptr_pam_user = &pam_user; 483 char *tz = getenv("TZ"); 484 485 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 486 (sshpam_const void **)ptr_pam_user); 487 if (sshpam_err != PAM_SUCCESS) 488 goto auth_fail; 489 490 environ[0] = NULL; 491 if (tz != NULL) 492 if (setenv("TZ", tz, 1) == -1) 493 error("PAM: could not set TZ environment: %s", 494 strerror(errno)); 495 496 if (sshpam_authctxt != NULL) { 497 setproctitle("%s [pam]", 498 sshpam_authctxt->valid ? pam_user : "unknown"); 499 } 500 #endif 501 502 sshpam_conv.conv = sshpam_thread_conv; 503 sshpam_conv.appdata_ptr = ctxt; 504 505 if (sshpam_authctxt == NULL) 506 fatal("%s: PAM authctxt not initialized", __func__); 507 508 if ((buffer = sshbuf_new()) == NULL) 509 fatal("%s: sshbuf_new failed", __func__); 510 511 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 512 (const void *)&sshpam_conv); 513 if (sshpam_err != PAM_SUCCESS) 514 goto auth_fail; 515 sshpam_err = pam_authenticate(sshpam_handle, flags); 516 if (sshpam_err == PAM_MAXTRIES) 517 sshpam_set_maxtries_reached(1); 518 if (sshpam_err != PAM_SUCCESS) 519 goto auth_fail; 520 521 if (!do_pam_account()) { 522 sshpam_err = PAM_ACCT_EXPIRED; 523 goto auth_fail; 524 } 525 if (sshpam_authctxt->force_pwchange) { 526 sshpam_err = pam_chauthtok(sshpam_handle, 527 PAM_CHANGE_EXPIRED_AUTHTOK); 528 if (sshpam_err != PAM_SUCCESS) 529 goto auth_fail; 530 sshpam_password_change_required(0); 531 } 532 533 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 534 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 535 536 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 537 /* Export variables set by do_pam_account */ 538 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 539 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 540 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 541 542 /* Export any environment strings set in child */ 543 for (i = 0; environ[i] != NULL; i++) { 544 /* Count */ 545 if (i > INT_MAX) 546 fatal("%s: too many environment strings", __func__); 547 } 548 if ((r = sshbuf_put_u32(buffer, i)) != 0) 549 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 550 for (i = 0; environ[i] != NULL; i++) { 551 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 552 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 553 } 554 /* Export any environment strings set by PAM in child */ 555 env_from_pam = pam_getenvlist(sshpam_handle); 556 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 557 /* Count */ 558 if (i > INT_MAX) 559 fatal("%s: too many PAM environment strings", __func__); 560 } 561 if ((r = sshbuf_put_u32(buffer, i)) != 0) 562 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 563 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 564 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 565 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 566 } 567 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 568 569 /* XXX - can't do much about an error here */ 570 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 571 sshbuf_free(buffer); 572 pthread_exit(NULL); 573 574 auth_fail: 575 if ((r = sshbuf_put_cstring(buffer, 576 pam_strerror(sshpam_handle, sshpam_err))) != 0) 577 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 578 /* XXX - can't do much about an error here */ 579 if (sshpam_err == PAM_ACCT_EXPIRED) 580 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 581 else if (sshpam_maxtries_reached) 582 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 583 else 584 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 585 sshbuf_free(buffer); 586 pthread_exit(NULL); 587 588 return (NULL); /* Avoid warning for non-pthread case */ 589 } 590 591 void 592 sshpam_thread_cleanup(void) 593 { 594 struct pam_ctxt *ctxt = cleanup_ctxt; 595 596 debug3("PAM: %s entering", __func__); 597 if (ctxt != NULL && ctxt->pam_thread != 0) { 598 pthread_cancel(ctxt->pam_thread); 599 pthread_join(ctxt->pam_thread, NULL); 600 close(ctxt->pam_psock); 601 close(ctxt->pam_csock); 602 memset(ctxt, 0, sizeof(*ctxt)); 603 cleanup_ctxt = NULL; 604 } 605 } 606 607 static int 608 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 609 struct pam_response **resp, void *data) 610 { 611 debug3("PAM: %s entering, %d messages", __func__, n); 612 return (PAM_CONV_ERR); 613 } 614 615 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 616 617 static int 618 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 619 struct pam_response **resp, void *data) 620 { 621 struct pam_response *reply; 622 int r, i; 623 624 debug3("PAM: %s called with %d messages", __func__, n); 625 *resp = NULL; 626 627 if (n <= 0 || n > PAM_MAX_NUM_MSG) 628 return (PAM_CONV_ERR); 629 630 if ((reply = calloc(n, sizeof(*reply))) == NULL) 631 return (PAM_CONV_ERR); 632 633 for (i = 0; i < n; ++i) { 634 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 635 case PAM_ERROR_MSG: 636 case PAM_TEXT_INFO: 637 if ((r = sshbuf_putf(loginmsg, "%s\n", 638 PAM_MSG_MEMBER(msg, i, msg))) != 0) 639 fatal("%s: buffer error: %s", 640 __func__, ssh_err(r)); 641 reply[i].resp_retcode = PAM_SUCCESS; 642 break; 643 default: 644 goto fail; 645 } 646 } 647 *resp = reply; 648 return (PAM_SUCCESS); 649 650 fail: 651 for(i = 0; i < n; i++) { 652 free(reply[i].resp); 653 } 654 free(reply); 655 return (PAM_CONV_ERR); 656 } 657 658 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 659 660 void 661 sshpam_cleanup(void) 662 { 663 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 664 return; 665 debug("PAM: cleanup"); 666 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 667 if (sshpam_session_open) { 668 debug("PAM: closing session"); 669 pam_close_session(sshpam_handle, PAM_SILENT); 670 sshpam_session_open = 0; 671 } 672 if (sshpam_cred_established) { 673 debug("PAM: deleting credentials"); 674 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 675 sshpam_cred_established = 0; 676 } 677 sshpam_authenticated = 0; 678 pam_end(sshpam_handle, sshpam_err); 679 sshpam_handle = NULL; 680 } 681 682 static int 683 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 684 { 685 const char *pam_user, *user = authctxt->user; 686 const char **ptr_pam_user = &pam_user; 687 688 if (sshpam_handle == NULL) { 689 if (ssh == NULL) { 690 fatal("%s: called initially with no " 691 "packet context", __func__); 692 } 693 } if (sshpam_handle != NULL) { 694 /* We already have a PAM context; check if the user matches */ 695 sshpam_err = pam_get_item(sshpam_handle, 696 PAM_USER, (sshpam_const void **)ptr_pam_user); 697 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 698 return (0); 699 pam_end(sshpam_handle, sshpam_err); 700 sshpam_handle = NULL; 701 } 702 debug("PAM: initializing for \"%s\"", user); 703 sshpam_err = 704 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 705 sshpam_authctxt = authctxt; 706 707 if (sshpam_err != PAM_SUCCESS) { 708 pam_end(sshpam_handle, sshpam_err); 709 sshpam_handle = NULL; 710 return (-1); 711 } 712 713 if (ssh != NULL && sshpam_rhost == NULL) { 714 /* 715 * We need to cache these as we don't have packet context 716 * during the kbdint flow. 717 */ 718 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 719 options.use_dns)); 720 sshpam_laddr = get_local_ipaddr( 721 ssh_packet_get_connection_in(ssh)); 722 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 723 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 724 sshpam_laddr, ssh_local_port(ssh)); 725 } 726 if (sshpam_rhost != NULL) { 727 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 728 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 729 sshpam_rhost); 730 if (sshpam_err != PAM_SUCCESS) { 731 pam_end(sshpam_handle, sshpam_err); 732 sshpam_handle = NULL; 733 return (-1); 734 } 735 /* Put SSH_CONNECTION in the PAM environment too */ 736 pam_putenv(sshpam_handle, sshpam_conninfo); 737 } 738 739 #ifdef PAM_TTY_KLUDGE 740 /* 741 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 742 * sshd doesn't set the tty until too late in the auth process and 743 * may not even set one (for tty-less connections) 744 */ 745 debug("PAM: setting PAM_TTY to \"ssh\""); 746 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 747 if (sshpam_err != PAM_SUCCESS) { 748 pam_end(sshpam_handle, sshpam_err); 749 sshpam_handle = NULL; 750 return (-1); 751 } 752 #endif 753 return (0); 754 } 755 756 static void 757 expose_authinfo(const char *caller) 758 { 759 char *auth_info; 760 761 /* 762 * Expose authentication information to PAM. 763 * The environment variable is versioned. Please increment the 764 * version suffix if the format of session_info changes. 765 */ 766 if (sshpam_authctxt->session_info == NULL) 767 auth_info = xstrdup(""); 768 else if ((auth_info = sshbuf_dup_string( 769 sshpam_authctxt->session_info)) == NULL) 770 fatal("%s: sshbuf_dup_string failed", __func__); 771 772 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 773 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 774 free(auth_info); 775 } 776 777 static void * 778 sshpam_init_ctx(Authctxt *authctxt) 779 { 780 struct pam_ctxt *ctxt; 781 int result, socks[2]; 782 783 debug3("PAM: %s entering", __func__); 784 /* 785 * Refuse to start if we don't have PAM enabled or do_pam_account 786 * has previously failed. 787 */ 788 if (!options.use_pam || sshpam_account_status == 0) 789 return NULL; 790 791 /* Initialize PAM */ 792 if (sshpam_init(NULL, authctxt) == -1) { 793 error("PAM: initialization failed"); 794 return (NULL); 795 } 796 797 expose_authinfo(__func__); 798 ctxt = xcalloc(1, sizeof *ctxt); 799 800 /* Start the authentication thread */ 801 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 802 error("PAM: failed create sockets: %s", strerror(errno)); 803 free(ctxt); 804 return (NULL); 805 } 806 ctxt->pam_psock = socks[0]; 807 ctxt->pam_csock = socks[1]; 808 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 809 if (result != 0) { 810 error("PAM: failed to start authentication thread: %s", 811 strerror(result)); 812 close(socks[0]); 813 close(socks[1]); 814 free(ctxt); 815 return (NULL); 816 } 817 cleanup_ctxt = ctxt; 818 return (ctxt); 819 } 820 821 static int 822 sshpam_query(void *ctx, char **name, char **info, 823 u_int *num, char ***prompts, u_int **echo_on) 824 { 825 struct sshbuf *buffer; 826 struct pam_ctxt *ctxt = ctx; 827 size_t plen; 828 u_char type; 829 char *msg; 830 size_t len, mlen; 831 int r; 832 833 debug3("PAM: %s entering", __func__); 834 if ((buffer = sshbuf_new()) == NULL) 835 fatal("%s: sshbuf_new failed", __func__); 836 *name = xstrdup(""); 837 *info = xstrdup(""); 838 *prompts = xmalloc(sizeof(char *)); 839 **prompts = NULL; 840 plen = 0; 841 *echo_on = xmalloc(sizeof(u_int)); 842 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 843 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 844 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 845 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 846 switch (type) { 847 case PAM_PROMPT_ECHO_ON: 848 case PAM_PROMPT_ECHO_OFF: 849 *num = 1; 850 len = plen + mlen + 1; 851 **prompts = xreallocarray(**prompts, 1, len); 852 strlcpy(**prompts + plen, msg, len - plen); 853 plen += mlen; 854 **echo_on = (type == PAM_PROMPT_ECHO_ON); 855 free(msg); 856 sshbuf_free(buffer); 857 return (0); 858 case PAM_ERROR_MSG: 859 case PAM_TEXT_INFO: 860 /* accumulate messages */ 861 len = plen + mlen + 2; 862 **prompts = xreallocarray(**prompts, 1, len); 863 strlcpy(**prompts + plen, msg, len - plen); 864 plen += mlen; 865 strlcat(**prompts + plen, "\n", len - plen); 866 plen++; 867 free(msg); 868 break; 869 case PAM_ACCT_EXPIRED: 870 case PAM_MAXTRIES: 871 if (type == PAM_ACCT_EXPIRED) 872 sshpam_account_status = 0; 873 if (type == PAM_MAXTRIES) 874 sshpam_set_maxtries_reached(1); 875 /* FALLTHROUGH */ 876 case PAM_AUTH_ERR: 877 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 878 if (**prompts != NULL && strlen(**prompts) != 0) { 879 *info = **prompts; 880 **prompts = NULL; 881 *num = 0; 882 **echo_on = 0; 883 ctxt->pam_done = -1; 884 free(msg); 885 sshbuf_free(buffer); 886 return 0; 887 } 888 /* FALLTHROUGH */ 889 case PAM_SUCCESS: 890 if (**prompts != NULL) { 891 /* drain any accumulated messages */ 892 debug("PAM: %s", **prompts); 893 if ((r = sshbuf_put(loginmsg, **prompts, 894 strlen(**prompts))) != 0) 895 fatal("%s: buffer error: %s", 896 __func__, ssh_err(r)); 897 free(**prompts); 898 **prompts = NULL; 899 } 900 if (type == PAM_SUCCESS) { 901 if (!sshpam_authctxt->valid || 902 (sshpam_authctxt->pw->pw_uid == 0 && 903 options.permit_root_login != PERMIT_YES)) 904 fatal("Internal error: PAM auth " 905 "succeeded when it should have " 906 "failed"); 907 import_environments(buffer); 908 *num = 0; 909 **echo_on = 0; 910 ctxt->pam_done = 1; 911 free(msg); 912 sshbuf_free(buffer); 913 return (0); 914 } 915 error("PAM: %s for %s%.100s from %.100s", msg, 916 sshpam_authctxt->valid ? "" : "illegal user ", 917 sshpam_authctxt->user, sshpam_rhost); 918 /* FALLTHROUGH */ 919 default: 920 *num = 0; 921 **echo_on = 0; 922 free(msg); 923 ctxt->pam_done = -1; 924 sshbuf_free(buffer); 925 return (-1); 926 } 927 } 928 sshbuf_free(buffer); 929 return (-1); 930 } 931 932 /* 933 * Returns a junk password of identical length to that the user supplied. 934 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 935 * vary processing time in proportion to password length. 936 */ 937 static char * 938 fake_password(const char *wire_password) 939 { 940 const char junk[] = "\b\n\r\177INCORRECT"; 941 char *ret = NULL; 942 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 943 944 if (l >= INT_MAX) 945 fatal("%s: password length too long: %zu", __func__, l); 946 947 ret = malloc(l + 1); 948 if (ret == NULL) 949 return NULL; 950 for (i = 0; i < l; i++) 951 ret[i] = junk[i % (sizeof(junk) - 1)]; 952 ret[i] = '\0'; 953 return ret; 954 } 955 956 /* XXX - see also comment in auth-chall.c:verify_response */ 957 static int 958 sshpam_respond(void *ctx, u_int num, char **resp) 959 { 960 struct sshbuf *buffer; 961 struct pam_ctxt *ctxt = ctx; 962 char *fake; 963 int r; 964 965 debug2("PAM: %s entering, %u responses", __func__, num); 966 switch (ctxt->pam_done) { 967 case 1: 968 sshpam_authenticated = 1; 969 return (0); 970 case 0: 971 break; 972 default: 973 return (-1); 974 } 975 if (num != 1) { 976 error("PAM: expected one response, got %u", num); 977 return (-1); 978 } 979 if ((buffer = sshbuf_new()) == NULL) 980 fatal("%s: sshbuf_new failed", __func__); 981 if (sshpam_authctxt->valid && 982 (sshpam_authctxt->pw->pw_uid != 0 || 983 options.permit_root_login == PERMIT_YES)) { 984 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 985 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 986 } else { 987 fake = fake_password(*resp); 988 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 989 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 990 free(fake); 991 } 992 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 993 sshbuf_free(buffer); 994 return (-1); 995 } 996 sshbuf_free(buffer); 997 return (1); 998 } 999 1000 static void 1001 sshpam_free_ctx(void *ctxtp) 1002 { 1003 struct pam_ctxt *ctxt = ctxtp; 1004 1005 debug3("PAM: %s entering", __func__); 1006 sshpam_thread_cleanup(); 1007 free(ctxt); 1008 /* 1009 * We don't call sshpam_cleanup() here because we may need the PAM 1010 * handle at a later stage, e.g. when setting up a session. It's 1011 * still on the cleanup list, so pam_end() *will* be called before 1012 * the server process terminates. 1013 */ 1014 } 1015 1016 KbdintDevice sshpam_device = { 1017 "pam", 1018 sshpam_init_ctx, 1019 sshpam_query, 1020 sshpam_respond, 1021 sshpam_free_ctx 1022 }; 1023 1024 KbdintDevice mm_sshpam_device = { 1025 "pam", 1026 mm_sshpam_init_ctx, 1027 mm_sshpam_query, 1028 mm_sshpam_respond, 1029 mm_sshpam_free_ctx 1030 }; 1031 1032 /* 1033 * This replaces auth-pam.c 1034 */ 1035 void 1036 start_pam(struct ssh *ssh) 1037 { 1038 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1039 1040 if (!options.use_pam) 1041 fatal("PAM: initialisation requested when UsePAM=no"); 1042 1043 if (sshpam_init(ssh, authctxt) == -1) 1044 fatal("PAM: initialisation failed"); 1045 } 1046 1047 void 1048 finish_pam(void) 1049 { 1050 sshpam_cleanup(); 1051 } 1052 1053 1054 u_int 1055 do_pam_account(void) 1056 { 1057 debug("%s: called", __func__); 1058 if (sshpam_account_status != -1) 1059 return (sshpam_account_status); 1060 1061 expose_authinfo(__func__); 1062 1063 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1064 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1065 pam_strerror(sshpam_handle, sshpam_err)); 1066 1067 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1068 sshpam_account_status = 0; 1069 return (sshpam_account_status); 1070 } 1071 1072 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1073 sshpam_password_change_required(1); 1074 1075 sshpam_account_status = 1; 1076 return (sshpam_account_status); 1077 } 1078 1079 void 1080 do_pam_setcred(int init) 1081 { 1082 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1083 (const void *)&store_conv); 1084 if (sshpam_err != PAM_SUCCESS) 1085 fatal("PAM: failed to set PAM_CONV: %s", 1086 pam_strerror(sshpam_handle, sshpam_err)); 1087 if (init) { 1088 debug("PAM: establishing credentials"); 1089 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1090 } else { 1091 debug("PAM: reinitializing credentials"); 1092 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1093 } 1094 if (sshpam_err == PAM_SUCCESS) { 1095 sshpam_cred_established = 1; 1096 return; 1097 } 1098 if (sshpam_authenticated) 1099 fatal("PAM: pam_setcred(): %s", 1100 pam_strerror(sshpam_handle, sshpam_err)); 1101 else 1102 debug("PAM: pam_setcred(): %s", 1103 pam_strerror(sshpam_handle, sshpam_err)); 1104 } 1105 1106 static int 1107 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1108 struct pam_response **resp, void *data) 1109 { 1110 char input[PAM_MAX_MSG_SIZE]; 1111 struct pam_response *reply; 1112 int i; 1113 1114 debug3("PAM: %s called with %d messages", __func__, n); 1115 1116 *resp = NULL; 1117 1118 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1119 return (PAM_CONV_ERR); 1120 1121 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1122 return (PAM_CONV_ERR); 1123 1124 for (i = 0; i < n; ++i) { 1125 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1126 case PAM_PROMPT_ECHO_OFF: 1127 reply[i].resp = 1128 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1129 RP_ALLOW_STDIN); 1130 reply[i].resp_retcode = PAM_SUCCESS; 1131 break; 1132 case PAM_PROMPT_ECHO_ON: 1133 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1134 if (fgets(input, sizeof input, stdin) == NULL) 1135 input[0] = '\0'; 1136 if ((reply[i].resp = strdup(input)) == NULL) 1137 goto fail; 1138 reply[i].resp_retcode = PAM_SUCCESS; 1139 break; 1140 case PAM_ERROR_MSG: 1141 case PAM_TEXT_INFO: 1142 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1143 reply[i].resp_retcode = PAM_SUCCESS; 1144 break; 1145 default: 1146 goto fail; 1147 } 1148 } 1149 *resp = reply; 1150 return (PAM_SUCCESS); 1151 1152 fail: 1153 for(i = 0; i < n; i++) { 1154 free(reply[i].resp); 1155 } 1156 free(reply); 1157 return (PAM_CONV_ERR); 1158 } 1159 1160 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1161 1162 /* 1163 * XXX this should be done in the authentication phase, but ssh1 doesn't 1164 * support that 1165 */ 1166 void 1167 do_pam_chauthtok(void) 1168 { 1169 if (use_privsep) 1170 fatal("Password expired (unable to change with privsep)"); 1171 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1172 (const void *)&tty_conv); 1173 if (sshpam_err != PAM_SUCCESS) 1174 fatal("PAM: failed to set PAM_CONV: %s", 1175 pam_strerror(sshpam_handle, sshpam_err)); 1176 debug("PAM: changing password"); 1177 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1178 if (sshpam_err != PAM_SUCCESS) 1179 fatal("PAM: pam_chauthtok(): %s", 1180 pam_strerror(sshpam_handle, sshpam_err)); 1181 } 1182 1183 void 1184 do_pam_session(struct ssh *ssh) 1185 { 1186 debug3("PAM: opening session"); 1187 1188 expose_authinfo(__func__); 1189 1190 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1191 (const void *)&store_conv); 1192 if (sshpam_err != PAM_SUCCESS) 1193 fatal("PAM: failed to set PAM_CONV: %s", 1194 pam_strerror(sshpam_handle, sshpam_err)); 1195 sshpam_err = pam_open_session(sshpam_handle, 0); 1196 if (sshpam_err == PAM_SUCCESS) 1197 sshpam_session_open = 1; 1198 else { 1199 sshpam_session_open = 0; 1200 auth_restrict_session(ssh); 1201 error("PAM: pam_open_session(): %s", 1202 pam_strerror(sshpam_handle, sshpam_err)); 1203 } 1204 1205 } 1206 1207 int 1208 is_pam_session_open(void) 1209 { 1210 return sshpam_session_open; 1211 } 1212 1213 /* 1214 * Set a PAM environment string. We need to do this so that the session 1215 * modules can handle things like Kerberos/GSI credentials that appear 1216 * during the ssh authentication process. 1217 */ 1218 int 1219 do_pam_putenv(char *name, char *value) 1220 { 1221 int ret = 1; 1222 char *compound; 1223 size_t len; 1224 1225 len = strlen(name) + strlen(value) + 2; 1226 compound = xmalloc(len); 1227 1228 snprintf(compound, len, "%s=%s", name, value); 1229 ret = pam_putenv(sshpam_handle, compound); 1230 free(compound); 1231 1232 return (ret); 1233 } 1234 1235 char ** 1236 fetch_pam_child_environment(void) 1237 { 1238 return sshpam_env; 1239 } 1240 1241 char ** 1242 fetch_pam_environment(void) 1243 { 1244 return (pam_getenvlist(sshpam_handle)); 1245 } 1246 1247 void 1248 free_pam_environment(char **env) 1249 { 1250 char **envp; 1251 1252 if (env == NULL) 1253 return; 1254 1255 for (envp = env; *envp; envp++) 1256 free(*envp); 1257 free(env); 1258 } 1259 1260 /* 1261 * "Blind" conversation function for password authentication. Assumes that 1262 * echo-off prompts are for the password and stores messages for later 1263 * display. 1264 */ 1265 static int 1266 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1267 struct pam_response **resp, void *data) 1268 { 1269 struct pam_response *reply; 1270 int r, i; 1271 size_t len; 1272 1273 debug3("PAM: %s called with %d messages", __func__, n); 1274 1275 *resp = NULL; 1276 1277 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1278 return (PAM_CONV_ERR); 1279 1280 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1281 return (PAM_CONV_ERR); 1282 1283 for (i = 0; i < n; ++i) { 1284 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1285 case PAM_PROMPT_ECHO_OFF: 1286 if (sshpam_password == NULL) 1287 goto fail; 1288 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1289 goto fail; 1290 reply[i].resp_retcode = PAM_SUCCESS; 1291 break; 1292 case PAM_ERROR_MSG: 1293 case PAM_TEXT_INFO: 1294 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1295 if (len > 0) { 1296 if ((r = sshbuf_putf(loginmsg, "%s\n", 1297 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1298 fatal("%s: buffer error: %s", 1299 __func__, ssh_err(r)); 1300 } 1301 if ((reply[i].resp = strdup("")) == NULL) 1302 goto fail; 1303 reply[i].resp_retcode = PAM_SUCCESS; 1304 break; 1305 default: 1306 goto fail; 1307 } 1308 } 1309 *resp = reply; 1310 return (PAM_SUCCESS); 1311 1312 fail: 1313 for(i = 0; i < n; i++) { 1314 free(reply[i].resp); 1315 } 1316 free(reply); 1317 return (PAM_CONV_ERR); 1318 } 1319 1320 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1321 1322 /* 1323 * Attempt password authentication via PAM 1324 */ 1325 int 1326 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1327 { 1328 int flags = (options.permit_empty_passwd == 0 ? 1329 PAM_DISALLOW_NULL_AUTHTOK : 0); 1330 char *fake = NULL; 1331 1332 if (!options.use_pam || sshpam_handle == NULL) 1333 fatal("PAM: %s called when PAM disabled or failed to " 1334 "initialise.", __func__); 1335 1336 sshpam_password = password; 1337 sshpam_authctxt = authctxt; 1338 1339 /* 1340 * If the user logging in is invalid, or is root but is not permitted 1341 * by PermitRootLogin, use an invalid password to prevent leaking 1342 * information via timing (eg if the PAM config has a delay on fail). 1343 */ 1344 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1345 options.permit_root_login != PERMIT_YES)) 1346 sshpam_password = fake = fake_password(password); 1347 1348 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1349 (const void *)&passwd_conv); 1350 if (sshpam_err != PAM_SUCCESS) 1351 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1352 pam_strerror(sshpam_handle, sshpam_err)); 1353 1354 sshpam_err = pam_authenticate(sshpam_handle, flags); 1355 sshpam_password = NULL; 1356 free(fake); 1357 if (sshpam_err == PAM_MAXTRIES) 1358 sshpam_set_maxtries_reached(1); 1359 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1360 debug("PAM: password authentication accepted for %.100s", 1361 authctxt->user); 1362 return 1; 1363 } else { 1364 debug("PAM: password authentication failed for %.100s: %s", 1365 authctxt->valid ? authctxt->user : "an illegal user", 1366 pam_strerror(sshpam_handle, sshpam_err)); 1367 return 0; 1368 } 1369 } 1370 1371 int 1372 sshpam_get_maxtries_reached(void) 1373 { 1374 return sshpam_maxtries_reached; 1375 } 1376 1377 void 1378 sshpam_set_maxtries_reached(int reached) 1379 { 1380 if (reached == 0 || sshpam_maxtries_reached) 1381 return; 1382 sshpam_maxtries_reached = 1; 1383 options.password_authentication = 0; 1384 options.kbd_interactive_authentication = 0; 1385 options.challenge_response_authentication = 0; 1386 } 1387 #endif /* USE_PAM */ 1388