crypto/openssh/monitor.c

   1 /* $OpenBSD: monitor.c,v 1.174 2017/10/02 19:33:20 djm Exp $ */
   2 /*
   3  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
   4  * Copyright 2002 Markus Friedl <markus@openbsd.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/socket.h>
  32 #include "openbsd-compat/sys-tree.h"
  33 #include <sys/wait.h>
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <limits.h>
  38 #ifdef HAVE_PATHS_H
  39 #include <paths.h>
  40 #endif
  41 #include <pwd.h>
  42 #include <signal.h>
  43 #ifdef HAVE_STDINT_H
  44 #include <stdint.h>
  45 #endif
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <stdarg.h>
  49 #include <stdio.h>
  50 #include <unistd.h>
  51 #ifdef HAVE_POLL_H
  52 #include <poll.h>
  53 #else
  54 # ifdef HAVE_SYS_POLL_H
  55 #  include <sys/poll.h>
  56 # endif
  57 #endif
  58
  59 #ifdef SKEY
  60 #include <skey.h>
  61 #endif
  62
  63 #ifdef WITH_OPENSSL
  64 #include <openssl/dh.h>
  65 #endif
  66
  67 #include "openbsd-compat/sys-queue.h"
  68 #include "atomicio.h"
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "key.h"
  72 #include "buffer.h"
  73 #include "hostfile.h"
  74 #include "auth.h"
  75 #include "cipher.h"
  76 #include "kex.h"
  77 #include "dh.h"
  78 #include "auth-pam.h"
  79 #ifdef TARGET_OS_MAC    /* XXX Broken krb5 headers on Mac */
  80 #undef TARGET_OS_MAC
  81 #include "zlib.h"
  82 #define TARGET_OS_MAC 1
  83 #else
  84 #include "zlib.h"
  85 #endif
  86 #include "packet.h"
  87 #include "auth-options.h"
  88 #include "sshpty.h"
  89 #include "channels.h"
  90 #include "session.h"
  91 #include "sshlogin.h"
  92 #include "canohost.h"
  93 #include "log.h"
  94 #include "misc.h"
  95 #include "servconf.h"
  96 #include "monitor.h"
  97 #ifdef GSSAPI
  98 #include "ssh-gss.h"
  99 #endif
 100 #include "monitor_wrap.h"
 101 #include "monitor_fdpass.h"
 102 #include "compat.h"
 103 #include "ssh2.h"
 104 #include "authfd.h"
 105 #include "match.h"
 106 #include "ssherr.h"
 107
 108 #ifdef GSSAPI
 109 static Gssctxt *gsscontext = NULL;
 110 #endif
 111
 112 /* Imports */
 113 extern ServerOptions options;
 114 extern u_int utmp_len;
 115 extern u_char session_id[];
 116 extern Buffer auth_debug;
 117 extern int auth_debug_init;
 118 extern Buffer loginmsg;
 119
 120 /* State exported from the child */
 121 static struct sshbuf *child_state;
 122
 123 /* Functions on the monitor that answer unprivileged requests */
 124
 125 int mm_answer_moduli(int, Buffer *);
 126 int mm_answer_sign(int, Buffer *);
 127 int mm_answer_pwnamallow(int, Buffer *);
 128 int mm_answer_auth2_read_banner(int, Buffer *);
 129 int mm_answer_authserv(int, Buffer *);
 130 int mm_answer_authpassword(int, Buffer *);
 131 int mm_answer_bsdauthquery(int, Buffer *);
 132 int mm_answer_bsdauthrespond(int, Buffer *);
 133 int mm_answer_skeyquery(int, Buffer *);
 134 int mm_answer_skeyrespond(int, Buffer *);
 135 int mm_answer_keyallowed(int, Buffer *);
 136 int mm_answer_keyverify(int, Buffer *);
 137 int mm_answer_pty(int, Buffer *);
 138 int mm_answer_pty_cleanup(int, Buffer *);
 139 int mm_answer_term(int, Buffer *);
 140 int mm_answer_rsa_keyallowed(int, Buffer *);
 141 int mm_answer_rsa_challenge(int, Buffer *);
 142 int mm_answer_rsa_response(int, Buffer *);
 143 int mm_answer_sesskey(int, Buffer *);
 144 int mm_answer_sessid(int, Buffer *);
 145
 146 #ifdef USE_PAM
 147 int mm_answer_pam_start(int, Buffer *);
 148 int mm_answer_pam_account(int, Buffer *);
 149 int mm_answer_pam_init_ctx(int, Buffer *);
 150 int mm_answer_pam_query(int, Buffer *);
 151 int mm_answer_pam_respond(int, Buffer *);
 152 int mm_answer_pam_free_ctx(int, Buffer *);
 153 #endif
 154
 155 #ifdef GSSAPI
 156 int mm_answer_gss_setup_ctx(int, Buffer *);
 157 int mm_answer_gss_accept_ctx(int, Buffer *);
 158 int mm_answer_gss_userok(int, Buffer *);
 159 int mm_answer_gss_checkmic(int, Buffer *);
 160 #endif
 161
 162 #ifdef SSH_AUDIT_EVENTS
 163 int mm_answer_audit_event(int, Buffer *);
 164 int mm_answer_audit_command(int, Buffer *);
 165 #endif
 166
 167 static int monitor_read_log(struct monitor *);
 168
 169 static Authctxt *authctxt;
 170
 171 /* local state for key verify */
 172 static u_char *key_blob = NULL;
 173 static u_int key_bloblen = 0;
 174 static int key_blobtype = MM_NOKEY;
 175 static char *hostbased_cuser = NULL;
 176 static char *hostbased_chost = NULL;
 177 static char *auth_method = "unknown";
 178 static char *auth_submethod = NULL;
 179 static u_int session_id2_len = 0;
 180 static u_char *session_id2 = NULL;
 181 static pid_t monitor_child_pid;
 182
 183 struct mon_table {
 184         enum monitor_reqtype type;
 185         int flags;
 186         int (*f)(int, Buffer *);
 187 };
 188
 189 #define MON_ISAUTH      0x0004  /* Required for Authentication */
 190 #define MON_AUTHDECIDE  0x0008  /* Decides Authentication */
 191 #define MON_ONCE        0x0010  /* Disable after calling */
 192 #define MON_ALOG        0x0020  /* Log auth attempt without authenticating */
 193
 194 #define MON_AUTH        (MON_ISAUTH|MON_AUTHDECIDE)
 195
 196 #define MON_PERMIT      0x1000  /* Request is permitted */
 197
 198 struct mon_table mon_dispatch_proto20[] = {
 199 #ifdef WITH_OPENSSL
 200     {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
 201 #endif
 202     {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
 203     {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
 204     {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
 205     {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
 206     {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
 207 #ifdef USE_PAM
 208     {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
 209     {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
 210     {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx},
 211     {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query},
 212     {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond},
 213     {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
 214 #endif
 215 #ifdef SSH_AUDIT_EVENTS
 216     {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
 217 #endif
 218 #ifdef BSD_AUTH
 219     {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
 220     {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
 221 #endif
 222 #ifdef SKEY
 223     {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery},
 224     {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond},
 225 #endif
 226     {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
 227     {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
 228 #ifdef GSSAPI
 229     {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
 230     {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
 231     {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
 232     {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
 233 #endif
 234     {0, 0, NULL}
 235 };
 236
 237 struct mon_table mon_dispatch_postauth20[] = {
 238 #ifdef WITH_OPENSSL
 239     {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
 240 #endif
 241     {MONITOR_REQ_SIGN, 0, mm_answer_sign},
 242     {MONITOR_REQ_PTY, 0, mm_answer_pty},
 243     {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
 244     {MONITOR_REQ_TERM, 0, mm_answer_term},
 245 #ifdef SSH_AUDIT_EVENTS
 246     {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
 247     {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
 248 #endif
 249     {0, 0, NULL}
 250 };
 251
 252 struct mon_table *mon_dispatch;
 253
 254 /* Specifies if a certain message is allowed at the moment */
 255
 256 static void
 257 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
 258 {
 259         while (ent->f != NULL) {
 260                 if (ent->type == type) {
 261                         ent->flags &= ~MON_PERMIT;
 262                         ent->flags |= permit ? MON_PERMIT : 0;
 263                         return;
 264                 }
 265                 ent++;
 266         }
 267 }
 268
 269 static void
 270 monitor_permit_authentications(int permit)
 271 {
 272         struct mon_table *ent = mon_dispatch;
 273
 274         while (ent->f != NULL) {
 275                 if (ent->flags & MON_AUTH) {
 276                         ent->flags &= ~MON_PERMIT;
 277                         ent->flags |= permit ? MON_PERMIT : 0;
 278                 }
 279                 ent++;
 280         }
 281 }
 282
 283 void
 284 monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor)
 285 {
 286         struct ssh *ssh = active_state; /* XXX */
 287         struct mon_table *ent;
 288         int authenticated = 0, partial = 0;
 289
 290         debug3("preauth child monitor started");
 291
 292         close(pmonitor->m_recvfd);
 293         close(pmonitor->m_log_sendfd);
 294         pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
 295
 296         authctxt = _authctxt;
 297         memset(authctxt, 0, sizeof(*authctxt));
 298
 299         authctxt->loginmsg = &loginmsg;
 300
 301         mon_dispatch = mon_dispatch_proto20;
 302         /* Permit requests for moduli and signatures */
 303         monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
 304         monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
 305
 306         /* The first few requests do not require asynchronous access */
 307         while (!authenticated) {
 308                 partial = 0;
 309                 auth_method = "unknown";
 310                 auth_submethod = NULL;
 311                 auth2_authctxt_reset_info(authctxt);
 312
 313                 authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1);
 314
 315                 /* Special handling for multiple required authentications */
 316                 if (options.num_auth_methods != 0) {
 317                         if (authenticated &&
 318                             !auth2_update_methods_lists(authctxt,
 319                             auth_method, auth_submethod)) {
 320                                 debug3("%s: method %s: partial", __func__,
 321                                     auth_method);
 322                                 authenticated = 0;
 323                                 partial = 1;
 324                         }
 325                 }
 326
 327                 if (authenticated) {
 328                         if (!(ent->flags & MON_AUTHDECIDE))
 329                                 fatal("%s: unexpected authentication from %d",
 330                                     __func__, ent->type);
 331                         if (authctxt->pw->pw_uid == 0 &&
 332                             !auth_root_allowed(auth_method))
 333                                 authenticated = 0;
 334 #ifdef USE_PAM
 335                         /* PAM needs to perform account checks after auth */
 336                         if (options.use_pam && authenticated) {
 337                                 Buffer m;
 338
 339                                 buffer_init(&m);
 340                                 mm_request_receive_expect(pmonitor->m_sendfd,
 341                                     MONITOR_REQ_PAM_ACCOUNT, &m);
 342                                 authenticated = mm_answer_pam_account(pmonitor->m_sendfd, &m);
 343                                 buffer_free(&m);
 344                         }
 345 #endif
 346                 }
 347                 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
 348                         auth_log(authctxt, authenticated, partial,
 349                             auth_method, auth_submethod);
 350                         if (!partial && !authenticated)
 351                                 authctxt->failures++;
 352                         if (authenticated || partial) {
 353                                 auth2_update_session_info(authctxt,
 354                                     auth_method, auth_submethod);
 355                         }
 356                 }
 357         }
 358
 359         if (!authctxt->valid)
 360                 fatal("%s: authenticated invalid user", __func__);
 361         if (strcmp(auth_method, "unknown") == 0)
 362                 fatal("%s: authentication method name unknown", __func__);
 363
 364         debug("%s: %s has been authenticated by privileged process",
 365             __func__, authctxt->user);
 366         ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
 367
 368         mm_get_keystate(pmonitor);
 369
 370         /* Drain any buffered messages from the child */
 371         while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
 372                 ;
 373
 374         close(pmonitor->m_sendfd);
 375         close(pmonitor->m_log_recvfd);
 376         pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
 377 }
 378
 379 static void
 380 monitor_set_child_handler(pid_t pid)
 381 {
 382         monitor_child_pid = pid;
 383 }
 384
 385 static void
 386 monitor_child_handler(int sig)
 387 {
 388         kill(monitor_child_pid, sig);
 389 }
 390
 391 void
 392 monitor_child_postauth(struct monitor *pmonitor)
 393 {
 394         close(pmonitor->m_recvfd);
 395         pmonitor->m_recvfd = -1;
 396
 397         monitor_set_child_handler(pmonitor->m_pid);
 398         signal(SIGHUP, &monitor_child_handler);
 399         signal(SIGTERM, &monitor_child_handler);
 400         signal(SIGINT, &monitor_child_handler);
 401 #ifdef SIGXFSZ
 402         signal(SIGXFSZ, SIG_IGN);
 403 #endif
 404
 405         mon_dispatch = mon_dispatch_postauth20;
 406
 407         /* Permit requests for moduli and signatures */
 408         monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
 409         monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
 410         monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
 411
 412         if (!no_pty_flag) {
 413                 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
 414                 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
 415         }
 416
 417         for (;;)
 418                 monitor_read(pmonitor, mon_dispatch, NULL);
 419 }
 420
 421 static int
 422 monitor_read_log(struct monitor *pmonitor)
 423 {
 424         Buffer logmsg;
 425         u_int len, level;
 426         char *msg;
 427
 428         buffer_init(&logmsg);
 429
 430         /* Read length */
 431         buffer_append_space(&logmsg, 4);
 432         if (atomicio(read, pmonitor->m_log_recvfd,
 433             buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) {
 434                 if (errno == EPIPE) {
 435                         buffer_free(&logmsg);
 436                         debug("%s: child log fd closed", __func__);
 437                         close(pmonitor->m_log_recvfd);
 438                         pmonitor->m_log_recvfd = -1;
 439                         return -1;
 440                 }
 441                 fatal("%s: log fd read: %s", __func__, strerror(errno));
 442         }
 443         len = buffer_get_int(&logmsg);
 444         if (len <= 4 || len > 8192)
 445                 fatal("%s: invalid log message length %u", __func__, len);
 446
 447         /* Read severity, message */
 448         buffer_clear(&logmsg);
 449         buffer_append_space(&logmsg, len);
 450         if (atomicio(read, pmonitor->m_log_recvfd,
 451             buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg))
 452                 fatal("%s: log fd read: %s", __func__, strerror(errno));
 453
 454         /* Log it */
 455         level = buffer_get_int(&logmsg);
 456         msg = buffer_get_string(&logmsg, NULL);
 457         if (log_level_name(level) == NULL)
 458                 fatal("%s: invalid log level %u (corrupted message?)",
 459                     __func__, level);
 460         do_log2(level, "%s [preauth]", msg);
 461
 462         buffer_free(&logmsg);
 463         free(msg);
 464
 465         return 0;
 466 }
 467
 468 int
 469 monitor_read(struct monitor *pmonitor, struct mon_table *ent,
 470     struct mon_table **pent)
 471 {
 472         Buffer m;
 473         int ret;
 474         u_char type;
 475         struct pollfd pfd[2];
 476
 477         for (;;) {
 478                 memset(&pfd, 0, sizeof(pfd));
 479                 pfd[0].fd = pmonitor->m_sendfd;
 480                 pfd[0].events = POLLIN;
 481                 pfd[1].fd = pmonitor->m_log_recvfd;
 482                 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
 483                 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
 484                         if (errno == EINTR || errno == EAGAIN)
 485                                 continue;
 486                         fatal("%s: poll: %s", __func__, strerror(errno));
 487                 }
 488                 if (pfd[1].revents) {
 489                         /*
 490                          * Drain all log messages before processing next
 491                          * monitor request.
 492                          */
 493                         monitor_read_log(pmonitor);
 494                         continue;
 495                 }
 496                 if (pfd[0].revents)
 497                         break;  /* Continues below */
 498         }
 499
 500         buffer_init(&m);
 501
 502         mm_request_receive(pmonitor->m_sendfd, &m);
 503         type = buffer_get_char(&m);
 504
 505         debug3("%s: checking request %d", __func__, type);
 506
 507         while (ent->f != NULL) {
 508                 if (ent->type == type)
 509                         break;
 510                 ent++;
 511         }
 512
 513         if (ent->f != NULL) {
 514                 if (!(ent->flags & MON_PERMIT))
 515                         fatal("%s: unpermitted request %d", __func__,
 516                             type);
 517                 ret = (*ent->f)(pmonitor->m_sendfd, &m);
 518                 buffer_free(&m);
 519
 520                 /* The child may use this request only once, disable it */
 521                 if (ent->flags & MON_ONCE) {
 522                         debug2("%s: %d used once, disabling now", __func__,
 523                             type);
 524                         ent->flags &= ~MON_PERMIT;
 525                 }
 526
 527                 if (pent != NULL)
 528                         *pent = ent;
 529
 530                 return ret;
 531         }
 532
 533         fatal("%s: unsupported request: %d", __func__, type);
 534
 535         /* NOTREACHED */
 536         return (-1);
 537 }
 538
 539 /* allowed key state */
 540 static int
 541 monitor_allowed_key(u_char *blob, u_int bloblen)
 542 {
 543         /* make sure key is allowed */
 544         if (key_blob == NULL || key_bloblen != bloblen ||
 545             timingsafe_bcmp(key_blob, blob, key_bloblen))
 546                 return (0);
 547         return (1);
 548 }
 549
 550 static void
 551 monitor_reset_key_state(void)
 552 {
 553         /* reset state */
 554         free(key_blob);
 555         free(hostbased_cuser);
 556         free(hostbased_chost);
 557         key_blob = NULL;
 558         key_bloblen = 0;
 559         key_blobtype = MM_NOKEY;
 560         hostbased_cuser = NULL;
 561         hostbased_chost = NULL;
 562 }
 563
 564 #ifdef WITH_OPENSSL
 565 int
 566 mm_answer_moduli(int sock, Buffer *m)
 567 {
 568         DH *dh;
 569         int min, want, max;
 570
 571         min = buffer_get_int(m);
 572         want = buffer_get_int(m);
 573         max = buffer_get_int(m);
 574
 575         debug3("%s: got parameters: %d %d %d",
 576             __func__, min, want, max);
 577         /* We need to check here, too, in case the child got corrupted */
 578         if (max < min || want < min || max < want)
 579                 fatal("%s: bad parameters: %d %d %d",
 580                     __func__, min, want, max);
 581
 582         buffer_clear(m);
 583
 584         dh = choose_dh(min, want, max);
 585         if (dh == NULL) {
 586                 buffer_put_char(m, 0);
 587                 return (0);
 588         } else {
 589                 /* Send first bignum */
 590                 buffer_put_char(m, 1);
 591                 buffer_put_bignum2(m, dh->p);
 592                 buffer_put_bignum2(m, dh->g);
 593
 594                 DH_free(dh);
 595         }
 596         mm_request_send(sock, MONITOR_ANS_MODULI, m);
 597         return (0);
 598 }
 599 #endif
 600
 601 int
 602 mm_answer_sign(int sock, Buffer *m)
 603 {
 604         struct ssh *ssh = active_state;         /* XXX */
 605         extern int auth_sock;                   /* XXX move to state struct? */
 606         struct sshkey *key;
 607         struct sshbuf *sigbuf = NULL;
 608         u_char *p = NULL, *signature = NULL;
 609         char *alg = NULL;
 610         size_t datlen, siglen, alglen;
 611         int r, is_proof = 0;
 612         u_int keyid;
 613         const char proof_req[] = "hostkeys-prove-00@openssh.com";
 614
 615         debug3("%s", __func__);
 616
 617         if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
 618             (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
 619             (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0)
 620                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 621         if (keyid > INT_MAX)
 622                 fatal("%s: invalid key ID", __func__);
 623
 624         /*
 625          * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
 626          * SHA384 (48 bytes) and SHA512 (64 bytes).
 627          *
 628          * Otherwise, verify the signature request is for a hostkey
 629          * proof.
 630          *
 631          * XXX perform similar check for KEX signature requests too?
 632          * it's not trivial, since what is signed is the hash, rather
 633          * than the full kex structure...
 634          */
 635         if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
 636                 /*
 637                  * Construct expected hostkey proof and compare it to what
 638                  * the client sent us.
 639                  */
 640                 if (session_id2_len == 0) /* hostkeys is never first */
 641                         fatal("%s: bad data length: %zu", __func__, datlen);
 642                 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
 643                         fatal("%s: no hostkey for index %d", __func__, keyid);
 644                 if ((sigbuf = sshbuf_new()) == NULL)
 645                         fatal("%s: sshbuf_new", __func__);
 646                 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
 647                     (r = sshbuf_put_string(sigbuf, session_id2,
 648                     session_id2_len)) != 0 ||
 649                     (r = sshkey_puts(key, sigbuf)) != 0)
 650                         fatal("%s: couldn't prepare private key "
 651                             "proof buffer: %s", __func__, ssh_err(r));
 652                 if (datlen != sshbuf_len(sigbuf) ||
 653                     memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
 654                         fatal("%s: bad data length: %zu, hostkey proof len %zu",
 655                             __func__, datlen, sshbuf_len(sigbuf));
 656                 sshbuf_free(sigbuf);
 657                 is_proof = 1;
 658         }
 659
 660         /* save session id, it will be passed on the first call */
 661         if (session_id2_len == 0) {
 662                 session_id2_len = datlen;
 663                 session_id2 = xmalloc(session_id2_len);
 664                 memcpy(session_id2, p, session_id2_len);
 665         }
 666
 667         if ((key = get_hostkey_by_index(keyid)) != NULL) {
 668                 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
 669                     datafellows)) != 0)
 670                         fatal("%s: sshkey_sign failed: %s",
 671                             __func__, ssh_err(r));
 672         } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
 673             auth_sock > 0) {
 674                 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
 675                     p, datlen, alg, datafellows)) != 0) {
 676                         fatal("%s: ssh_agent_sign failed: %s",
 677                             __func__, ssh_err(r));
 678                 }
 679         } else
 680                 fatal("%s: no hostkey from index %d", __func__, keyid);
 681
 682         debug3("%s: %s signature %p(%zu)", __func__,
 683             is_proof ? "KEX" : "hostkey proof", signature, siglen);
 684
 685         sshbuf_reset(m);
 686         if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
 687                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 688
 689         free(alg);
 690         free(p);
 691         free(signature);
 692
 693         mm_request_send(sock, MONITOR_ANS_SIGN, m);
 694
 695         /* Turn on permissions for getpwnam */
 696         monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
 697
 698         return (0);
 699 }
 700
 701 /* Retrieves the password entry and also checks if the user is permitted */
 702
 703 int
 704 mm_answer_pwnamallow(int sock, Buffer *m)
 705 {
 706         struct ssh *ssh = active_state; /* XXX */
 707         char *username;
 708         struct passwd *pwent;
 709         int allowed = 0;
 710         u_int i;
 711
 712         debug3("%s", __func__);
 713
 714         if (authctxt->attempt++ != 0)
 715                 fatal("%s: multiple attempts for getpwnam", __func__);
 716
 717         username = buffer_get_string(m, NULL);
 718
 719         pwent = getpwnamallow(username);
 720
 721         authctxt->user = xstrdup(username);
 722         setproctitle("%s [priv]", pwent ? username : "unknown");
 723         free(username);
 724
 725         buffer_clear(m);
 726
 727         if (pwent == NULL) {
 728                 buffer_put_char(m, 0);
 729                 authctxt->pw = fakepw();
 730                 goto out;
 731         }
 732
 733         allowed = 1;
 734         authctxt->pw = pwent;
 735         authctxt->valid = 1;
 736
 737         buffer_put_char(m, 1);
 738         buffer_put_string(m, pwent, sizeof(struct passwd));
 739         buffer_put_cstring(m, pwent->pw_name);
 740         buffer_put_cstring(m, "*");
 741 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
 742         buffer_put_cstring(m, pwent->pw_gecos);
 743 #endif
 744 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
 745         buffer_put_cstring(m, pwent->pw_class);
 746 #endif
 747         buffer_put_cstring(m, pwent->pw_dir);
 748         buffer_put_cstring(m, pwent->pw_shell);
 749
 750  out:
 751         ssh_packet_set_log_preamble(ssh, "%suser %s",
 752             authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
 753         buffer_put_string(m, &options, sizeof(options));
 754
 755 #define M_CP_STROPT(x) do { \
 756                 if (options.x != NULL) \
 757                         buffer_put_cstring(m, options.x); \
 758         } while (0)
 759 #define M_CP_STRARRAYOPT(x, nx) do { \
 760                 for (i = 0; i < options.nx; i++) \
 761                         buffer_put_cstring(m, options.x[i]); \
 762         } while (0)
 763 #define M_CP_STRARRAYOPT_ALLOC(x, nx) M_CP_STRARRAYOPT(x, nx)
 764         /* See comment in servconf.h */
 765         COPY_MATCH_STRING_OPTS();
 766 #undef M_CP_STROPT
 767 #undef M_CP_STRARRAYOPT
 768 #undef M_CP_STRARRAYOPT_ALLOC
 769
 770         /* Create valid auth method lists */
 771         if (auth2_setup_methods_lists(authctxt) != 0) {
 772                 /*
 773                  * The monitor will continue long enough to let the child
 774                  * run to it's packet_disconnect(), but it must not allow any
 775                  * authentication to succeed.
 776                  */
 777                 debug("%s: no valid authentication method lists", __func__);
 778         }
 779
 780         debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed);
 781         mm_request_send(sock, MONITOR_ANS_PWNAM, m);
 782
 783         /* Allow service/style information on the auth context */
 784         monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
 785         monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
 786
 787 #ifdef USE_PAM
 788         if (options.use_pam)
 789                 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
 790 #endif
 791
 792         return (0);
 793 }
 794
 795 int mm_answer_auth2_read_banner(int sock, Buffer *m)
 796 {
 797         char *banner;
 798
 799         buffer_clear(m);
 800         banner = auth2_read_banner();
 801         buffer_put_cstring(m, banner != NULL ? banner : "");
 802         mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
 803         free(banner);
 804
 805         return (0);
 806 }
 807
 808 int
 809 mm_answer_authserv(int sock, Buffer *m)
 810 {
 811         monitor_permit_authentications(1);
 812
 813         authctxt->service = buffer_get_string(m, NULL);
 814         authctxt->style = buffer_get_string(m, NULL);
 815         debug3("%s: service=%s, style=%s",
 816             __func__, authctxt->service, authctxt->style);
 817
 818         if (strlen(authctxt->style) == 0) {
 819                 free(authctxt->style);
 820                 authctxt->style = NULL;
 821         }
 822
 823         return (0);
 824 }
 825
 826 int
 827 mm_answer_authpassword(int sock, Buffer *m)
 828 {
 829         static int call_count;
 830         char *passwd;
 831         int authenticated;
 832         u_int plen;
 833
 834         if (!options.password_authentication)
 835                 fatal("%s: password authentication not enabled", __func__);
 836         passwd = buffer_get_string(m, &plen);
 837         /* Only authenticate if the context is valid */
 838         authenticated = options.password_authentication &&
 839             auth_password(authctxt, passwd);
 840         explicit_bzero(passwd, strlen(passwd));
 841         free(passwd);
 842
 843         buffer_clear(m);
 844         buffer_put_int(m, authenticated);
 845 #ifdef USE_PAM
 846         buffer_put_int(m, sshpam_get_maxtries_reached());
 847 #endif
 848
 849         debug3("%s: sending result %d", __func__, authenticated);
 850         mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m);
 851
 852         call_count++;
 853         if (plen == 0 && call_count == 1)
 854                 auth_method = "none";
 855         else
 856                 auth_method = "password";
 857
 858         /* Causes monitor loop to terminate if authenticated */
 859         return (authenticated);
 860 }
 861
 862 #ifdef BSD_AUTH
 863 int
 864 mm_answer_bsdauthquery(int sock, Buffer *m)
 865 {
 866         char *name, *infotxt;
 867         u_int numprompts;
 868         u_int *echo_on;
 869         char **prompts;
 870         u_int success;
 871
 872         if (!options.kbd_interactive_authentication)
 873                 fatal("%s: kbd-int authentication not enabled", __func__);
 874         success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
 875             &prompts, &echo_on) < 0 ? 0 : 1;
 876
 877         buffer_clear(m);
 878         buffer_put_int(m, success);
 879         if (success)
 880                 buffer_put_cstring(m, prompts[0]);
 881
 882         debug3("%s: sending challenge success: %u", __func__, success);
 883         mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
 884
 885         if (success) {
 886                 free(name);
 887                 free(infotxt);
 888                 free(prompts);
 889                 free(echo_on);
 890         }
 891
 892         return (0);
 893 }
 894
 895 int
 896 mm_answer_bsdauthrespond(int sock, Buffer *m)
 897 {
 898         char *response;
 899         int authok;
 900
 901         if (!options.kbd_interactive_authentication)
 902                 fatal("%s: kbd-int authentication not enabled", __func__);
 903         if (authctxt->as == NULL)
 904                 fatal("%s: no bsd auth session", __func__);
 905
 906         response = buffer_get_string(m, NULL);
 907         authok = options.challenge_response_authentication &&
 908             auth_userresponse(authctxt->as, response, 0);
 909         authctxt->as = NULL;
 910         debug3("%s: <%s> = <%d>", __func__, response, authok);
 911         free(response);
 912
 913         buffer_clear(m);
 914         buffer_put_int(m, authok);
 915
 916         debug3("%s: sending authenticated: %d", __func__, authok);
 917         mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
 918
 919         auth_method = "keyboard-interactive";
 920         auth_submethod = "bsdauth";
 921
 922         return (authok != 0);
 923 }
 924 #endif
 925
 926 #ifdef SKEY
 927 int
 928 mm_answer_skeyquery(int sock, Buffer *m)
 929 {
 930         struct skey skey;
 931         char challenge[1024];
 932         u_int success;
 933
 934         success = _compat_skeychallenge(&skey, authctxt->user, challenge,
 935             sizeof(challenge)) < 0 ? 0 : 1;
 936
 937         buffer_clear(m);
 938         buffer_put_int(m, success);
 939         if (success)
 940                 buffer_put_cstring(m, challenge);
 941
 942         debug3("%s: sending challenge success: %u", __func__, success);
 943         mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m);
 944
 945         return (0);
 946 }
 947
 948 int
 949 mm_answer_skeyrespond(int sock, Buffer *m)
 950 {
 951         char *response;
 952         int authok;
 953
 954         response = buffer_get_string(m, NULL);
 955
 956         authok = (options.challenge_response_authentication &&
 957             authctxt->valid &&
 958             skey_haskey(authctxt->pw->pw_name) == 0 &&
 959             skey_passcheck(authctxt->pw->pw_name, response) != -1);
 960
 961         free(response);
 962
 963         buffer_clear(m);
 964         buffer_put_int(m, authok);
 965
 966         debug3("%s: sending authenticated: %d", __func__, authok);
 967         mm_request_send(sock, MONITOR_ANS_SKEYRESPOND, m);
 968
 969         auth_method = "keyboard-interactive";
 970         auth_submethod = "skey";
 971
 972         return (authok != 0);
 973 }
 974 #endif
 975
 976 #ifdef USE_PAM
 977 int
 978 mm_answer_pam_start(int sock, Buffer *m)
 979 {
 980         if (!options.use_pam)
 981                 fatal("UsePAM not set, but ended up in %s anyway", __func__);
 982
 983         start_pam(authctxt);
 984
 985         monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
 986         if (options.kbd_interactive_authentication)
 987                 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
 988
 989         return (0);
 990 }
 991
 992 int
 993 mm_answer_pam_account(int sock, Buffer *m)
 994 {
 995         u_int ret;
 996
 997         if (!options.use_pam)
 998                 fatal("%s: PAM not enabled", __func__);
 999
1000         ret = do_pam_account();
1001
1002         buffer_put_int(m, ret);
1003         buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg));
1004
1005         mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
1006
1007         return (ret);
1008 }
1009
1010 static void *sshpam_ctxt, *sshpam_authok;
1011 extern KbdintDevice sshpam_device;
1012
1013 int
1014 mm_answer_pam_init_ctx(int sock, Buffer *m)
1015 {
1016         debug3("%s", __func__);
1017         if (!options.kbd_interactive_authentication)
1018                 fatal("%s: kbd-int authentication not enabled", __func__);
1019         if (sshpam_ctxt != NULL)
1020                 fatal("%s: already called", __func__);
1021         sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
1022         sshpam_authok = NULL;
1023         buffer_clear(m);
1024         if (sshpam_ctxt != NULL) {
1025                 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
1026                 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
1027                 buffer_put_int(m, 1);
1028         } else {
1029                 buffer_put_int(m, 0);
1030         }
1031         mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
1032         return (0);
1033 }
1034
1035 int
1036 mm_answer_pam_query(int sock, Buffer *m)
1037 {
1038         char *name = NULL, *info = NULL, **prompts = NULL;
1039         u_int i, num = 0, *echo_on = 0;
1040         int ret;
1041
1042         debug3("%s", __func__);
1043         sshpam_authok = NULL;
1044         if (sshpam_ctxt == NULL)
1045                 fatal("%s: no context", __func__);
1046         ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
1047             &num, &prompts, &echo_on);
1048         if (ret == 0 && num == 0)
1049                 sshpam_authok = sshpam_ctxt;
1050         if (num > 1 || name == NULL || info == NULL)
1051                 fatal("sshpam_device.query failed");
1052         monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
1053         buffer_clear(m);
1054         buffer_put_int(m, ret);
1055         buffer_put_cstring(m, name);
1056         free(name);
1057         buffer_put_cstring(m, info);
1058         free(info);
1059         buffer_put_int(m, sshpam_get_maxtries_reached());
1060         buffer_put_int(m, num);
1061         for (i = 0; i < num; ++i) {
1062                 buffer_put_cstring(m, prompts[i]);
1063                 free(prompts[i]);
1064                 buffer_put_int(m, echo_on[i]);
1065         }
1066         free(prompts);
1067         free(echo_on);
1068         auth_method = "keyboard-interactive";
1069         auth_submethod = "pam";
1070         mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
1071         return (0);
1072 }
1073
1074 int
1075 mm_answer_pam_respond(int sock, Buffer *m)
1076 {
1077         char **resp;
1078         u_int i, num;
1079         int ret;
1080
1081         debug3("%s", __func__);
1082         if (sshpam_ctxt == NULL)
1083                 fatal("%s: no context", __func__);
1084         sshpam_authok = NULL;
1085         num = buffer_get_int(m);
1086         if (num > 0) {
1087                 resp = xcalloc(num, sizeof(char *));
1088                 for (i = 0; i < num; ++i)
1089                         resp[i] = buffer_get_string(m, NULL);
1090                 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
1091                 for (i = 0; i < num; ++i)
1092                         free(resp[i]);
1093                 free(resp);
1094         } else {
1095                 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
1096         }
1097         buffer_clear(m);
1098         buffer_put_int(m, ret);
1099         mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
1100         auth_method = "keyboard-interactive";
1101         auth_submethod = "pam";
1102         if (ret == 0)
1103                 sshpam_authok = sshpam_ctxt;
1104         return (0);
1105 }
1106
1107 int
1108 mm_answer_pam_free_ctx(int sock, Buffer *m)
1109 {
1110         int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
1111
1112         debug3("%s", __func__);
1113         if (sshpam_ctxt == NULL)
1114                 fatal("%s: no context", __func__);
1115         (sshpam_device.free_ctx)(sshpam_ctxt);
1116         sshpam_ctxt = sshpam_authok = NULL;
1117         buffer_clear(m);
1118         mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
1119         /* Allow another attempt */
1120         monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1121         auth_method = "keyboard-interactive";
1122         auth_submethod = "pam";
1123         return r;
1124 }
1125 #endif
1126
1127 int
1128 mm_answer_keyallowed(int sock, Buffer *m)
1129 {
1130         struct sshkey *key;
1131         char *cuser, *chost;
1132         u_char *blob;
1133         u_int bloblen, pubkey_auth_attempt;
1134         enum mm_keytype type = 0;
1135         int allowed = 0;
1136
1137         debug3("%s entering", __func__);
1138
1139         type = buffer_get_int(m);
1140         cuser = buffer_get_string(m, NULL);
1141         chost = buffer_get_string(m, NULL);
1142         blob = buffer_get_string(m, &bloblen);
1143         pubkey_auth_attempt = buffer_get_int(m);
1144
1145         key = key_from_blob(blob, bloblen);
1146
1147         debug3("%s: key_from_blob: %p", __func__, key);
1148
1149         if (key != NULL && authctxt->valid) {
1150                 /* These should not make it past the privsep child */
1151                 if (key_type_plain(key->type) == KEY_RSA &&
1152                     (datafellows & SSH_BUG_RSASIGMD5) != 0)
1153                         fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__);
1154
1155                 switch (type) {
1156                 case MM_USERKEY:
1157                         allowed = options.pubkey_authentication &&
1158                             !auth2_key_already_used(authctxt, key) &&
1159                             match_pattern_list(sshkey_ssh_name(key),
1160                             options.pubkey_key_types, 0) == 1 &&
1161                             user_key_allowed(authctxt->pw, key,
1162                             pubkey_auth_attempt);
1163                         auth_method = "publickey";
1164                         if (options.pubkey_authentication &&
1165                             (!pubkey_auth_attempt || allowed != 1))
1166                                 auth_clear_options();
1167                         break;
1168                 case MM_HOSTKEY:
1169                         allowed = options.hostbased_authentication &&
1170                             !auth2_key_already_used(authctxt, key) &&
1171                             match_pattern_list(sshkey_ssh_name(key),
1172                             options.hostbased_key_types, 0) == 1 &&
1173                             hostbased_key_allowed(authctxt->pw,
1174                             cuser, chost, key);
1175                         auth2_record_info(authctxt,
1176                             "client user \"%.100s\", client host \"%.100s\"",
1177                             cuser, chost);
1178                         auth_method = "hostbased";
1179                         break;
1180                 default:
1181                         fatal("%s: unknown key type %d", __func__, type);
1182                         break;
1183                 }
1184         }
1185
1186         debug3("%s: key is %s", __func__, allowed ? "allowed" : "not allowed");
1187
1188         auth2_record_key(authctxt, 0, key);
1189         sshkey_free(key);
1190
1191         /* clear temporarily storage (used by verify) */
1192         monitor_reset_key_state();
1193
1194         if (allowed) {
1195                 /* Save temporarily for comparison in verify */
1196                 key_blob = blob;
1197                 key_bloblen = bloblen;
1198                 key_blobtype = type;
1199                 hostbased_cuser = cuser;
1200                 hostbased_chost = chost;
1201         } else {
1202                 /* Log failed attempt */
1203                 auth_log(authctxt, 0, 0, auth_method, NULL);
1204                 free(blob);
1205                 free(cuser);
1206                 free(chost);
1207         }
1208
1209         buffer_clear(m);
1210         buffer_put_int(m, allowed);
1211         buffer_put_int(m, forced_command != NULL);
1212
1213         mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
1214
1215         return (0);
1216 }
1217
1218 static int
1219 monitor_valid_userblob(u_char *data, u_int datalen)
1220 {
1221         Buffer b;
1222         u_char *p;
1223         char *userstyle, *cp;
1224         u_int len;
1225         int fail = 0;
1226
1227         buffer_init(&b);
1228         buffer_append(&b, data, datalen);
1229
1230         if (datafellows & SSH_OLD_SESSIONID) {
1231                 p = buffer_ptr(&b);
1232                 len = buffer_len(&b);
1233                 if ((session_id2 == NULL) ||
1234                     (len < session_id2_len) ||
1235                     (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1236                         fail++;
1237                 buffer_consume(&b, session_id2_len);
1238         } else {
1239                 p = buffer_get_string(&b, &len);
1240                 if ((session_id2 == NULL) ||
1241                     (len != session_id2_len) ||
1242                     (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1243                         fail++;
1244                 free(p);
1245         }
1246         if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
1247                 fail++;
1248         cp = buffer_get_cstring(&b, NULL);
1249         xasprintf(&userstyle, "%s%s%s", authctxt->user,
1250             authctxt->style ? ":" : "",
1251             authctxt->style ? authctxt->style : "");
1252         if (strcmp(userstyle, cp) != 0) {
1253                 logit("wrong user name passed to monitor: "
1254                     "expected %s != %.100s", userstyle, cp);
1255                 fail++;
1256         }
1257         free(userstyle);
1258         free(cp);
1259         buffer_skip_string(&b);
1260         if (datafellows & SSH_BUG_PKAUTH) {
1261                 if (!buffer_get_char(&b))
1262                         fail++;
1263         } else {
1264                 cp = buffer_get_cstring(&b, NULL);
1265                 if (strcmp("publickey", cp) != 0)
1266                         fail++;
1267                 free(cp);
1268                 if (!buffer_get_char(&b))
1269                         fail++;
1270                 buffer_skip_string(&b);
1271         }
1272         buffer_skip_string(&b);
1273         if (buffer_len(&b) != 0)
1274                 fail++;
1275         buffer_free(&b);
1276         return (fail == 0);
1277 }
1278
1279 static int
1280 monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser,
1281     char *chost)
1282 {
1283         Buffer b;
1284         char *p, *userstyle;
1285         u_int len;
1286         int fail = 0;
1287
1288         buffer_init(&b);
1289         buffer_append(&b, data, datalen);
1290
1291         p = buffer_get_string(&b, &len);
1292         if ((session_id2 == NULL) ||
1293             (len != session_id2_len) ||
1294             (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1295                 fail++;
1296         free(p);
1297
1298         if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
1299                 fail++;
1300         p = buffer_get_cstring(&b, NULL);
1301         xasprintf(&userstyle, "%s%s%s", authctxt->user,
1302             authctxt->style ? ":" : "",
1303             authctxt->style ? authctxt->style : "");
1304         if (strcmp(userstyle, p) != 0) {
1305                 logit("wrong user name passed to monitor: expected %s != %.100s",
1306                     userstyle, p);
1307                 fail++;
1308         }
1309         free(userstyle);
1310         free(p);
1311         buffer_skip_string(&b); /* service */
1312         p = buffer_get_cstring(&b, NULL);
1313         if (strcmp(p, "hostbased") != 0)
1314                 fail++;
1315         free(p);
1316         buffer_skip_string(&b); /* pkalg */
1317         buffer_skip_string(&b); /* pkblob */
1318
1319         /* verify client host, strip trailing dot if necessary */
1320         p = buffer_get_string(&b, NULL);
1321         if (((len = strlen(p)) > 0) && p[len - 1] == '.')
1322                 p[len - 1] = '\0';
1323         if (strcmp(p, chost) != 0)
1324                 fail++;
1325         free(p);
1326
1327         /* verify client user */
1328         p = buffer_get_string(&b, NULL);
1329         if (strcmp(p, cuser) != 0)
1330                 fail++;
1331         free(p);
1332
1333         if (buffer_len(&b) != 0)
1334                 fail++;
1335         buffer_free(&b);
1336         return (fail == 0);
1337 }
1338
1339 int
1340 mm_answer_keyverify(int sock, struct sshbuf *m)
1341 {
1342         struct sshkey *key;
1343         u_char *signature, *data, *blob;
1344         size_t signaturelen, datalen, bloblen;
1345         int r, ret, valid_data = 0, encoded_ret;
1346
1347         if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
1348             (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
1349             (r = sshbuf_get_string(m, &data, &datalen)) != 0)
1350                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1351
1352         if (hostbased_cuser == NULL || hostbased_chost == NULL ||
1353           !monitor_allowed_key(blob, bloblen))
1354                 fatal("%s: bad key, not previously allowed", __func__);
1355
1356         /* XXX use sshkey_froms here; need to change key_blob, etc. */
1357         if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
1358                 fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
1359
1360         switch (key_blobtype) {
1361         case MM_USERKEY:
1362                 valid_data = monitor_valid_userblob(data, datalen);
1363                 auth_method = "publickey";
1364                 break;
1365         case MM_HOSTKEY:
1366                 valid_data = monitor_valid_hostbasedblob(data, datalen,
1367                     hostbased_cuser, hostbased_chost);
1368                 auth_method = "hostbased";
1369                 break;
1370         default:
1371                 valid_data = 0;
1372                 break;
1373         }
1374         if (!valid_data)
1375                 fatal("%s: bad signature data blob", __func__);
1376
1377         ret = sshkey_verify(key, signature, signaturelen, data, datalen,
1378             active_state->compat);
1379         debug3("%s: %s %p signature %s", __func__, auth_method, key,
1380             (ret == 0) ? "verified" : "unverified");
1381         auth2_record_key(authctxt, ret == 0, key);
1382
1383         free(blob);
1384         free(signature);
1385         free(data);
1386
1387         monitor_reset_key_state();
1388
1389         sshkey_free(key);
1390         sshbuf_reset(m);
1391
1392         /* encode ret != 0 as positive integer, since we're sending u32 */
1393         encoded_ret = (ret != 0);
1394         if ((r = sshbuf_put_u32(m, encoded_ret)) != 0)
1395                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1396         mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
1397
1398         return ret == 0;
1399 }
1400
1401 static void
1402 mm_record_login(Session *s, struct passwd *pw)
1403 {
1404         struct ssh *ssh = active_state; /* XXX */
1405         socklen_t fromlen;
1406         struct sockaddr_storage from;
1407
1408         /*
1409          * Get IP address of client. If the connection is not a socket, let
1410          * the address be 0.0.0.0.
1411          */
1412         memset(&from, 0, sizeof(from));
1413         fromlen = sizeof(from);
1414         if (packet_connection_is_on_socket()) {
1415                 if (getpeername(packet_get_connection_in(),
1416                     (struct sockaddr *)&from, &fromlen) < 0) {
1417                         debug("getpeername: %.100s", strerror(errno));
1418                         cleanup_exit(255);
1419                 }
1420         }
1421         /* Record that there was a login on that tty from the remote host. */
1422         record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
1423             session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
1424             (struct sockaddr *)&from, fromlen);
1425 }
1426
1427 static void
1428 mm_session_close(Session *s)
1429 {
1430         debug3("%s: session %d pid %ld", __func__, s->self, (long)s->pid);
1431         if (s->ttyfd != -1) {
1432                 debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd);
1433                 session_pty_cleanup2(s);
1434         }
1435         session_unused(s->self);
1436 }
1437
1438 int
1439 mm_answer_pty(int sock, Buffer *m)
1440 {
1441         extern struct monitor *pmonitor;
1442         Session *s;
1443         int res, fd0;
1444
1445         debug3("%s entering", __func__);
1446
1447         buffer_clear(m);
1448         s = session_new();
1449         if (s == NULL)
1450                 goto error;
1451         s->authctxt = authctxt;
1452         s->pw = authctxt->pw;
1453         s->pid = pmonitor->m_pid;
1454         res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
1455         if (res == 0)
1456                 goto error;
1457         pty_setowner(authctxt->pw, s->tty);
1458
1459         buffer_put_int(m, 1);
1460         buffer_put_cstring(m, s->tty);
1461
1462         /* We need to trick ttyslot */
1463         if (dup2(s->ttyfd, 0) == -1)
1464                 fatal("%s: dup2", __func__);
1465
1466         mm_record_login(s, authctxt->pw);
1467
1468         /* Now we can close the file descriptor again */
1469         close(0);
1470
1471         /* send messages generated by record_login */
1472         buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg));
1473         buffer_clear(&loginmsg);
1474
1475         mm_request_send(sock, MONITOR_ANS_PTY, m);
1476
1477         if (mm_send_fd(sock, s->ptyfd) == -1 ||
1478             mm_send_fd(sock, s->ttyfd) == -1)
1479                 fatal("%s: send fds failed", __func__);
1480
1481         /* make sure nothing uses fd 0 */
1482         if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)
1483                 fatal("%s: open(/dev/null): %s", __func__, strerror(errno));
1484         if (fd0 != 0)
1485                 error("%s: fd0 %d != 0", __func__, fd0);
1486
1487         /* slave is not needed */
1488         close(s->ttyfd);
1489         s->ttyfd = s->ptyfd;
1490         /* no need to dup() because nobody closes ptyfd */
1491         s->ptymaster = s->ptyfd;
1492
1493         debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ttyfd);
1494
1495         return (0);
1496
1497  error:
1498         if (s != NULL)
1499                 mm_session_close(s);
1500         buffer_put_int(m, 0);
1501         mm_request_send(sock, MONITOR_ANS_PTY, m);
1502         return (0);
1503 }
1504
1505 int
1506 mm_answer_pty_cleanup(int sock, Buffer *m)
1507 {
1508         Session *s;
1509         char *tty;
1510
1511         debug3("%s entering", __func__);
1512
1513         tty = buffer_get_string(m, NULL);
1514         if ((s = session_by_tty(tty)) != NULL)
1515                 mm_session_close(s);
1516         buffer_clear(m);
1517         free(tty);
1518         return (0);
1519 }
1520
1521 int
1522 mm_answer_term(int sock, Buffer *req)
1523 {
1524         struct ssh *ssh = active_state; /* XXX */
1525         extern struct monitor *pmonitor;
1526         int res, status;
1527
1528         debug3("%s: tearing down sessions", __func__);
1529
1530         /* The child is terminating */
1531         session_destroy_all(ssh, &mm_session_close);
1532
1533 #ifdef USE_PAM
1534         if (options.use_pam)
1535                 sshpam_cleanup();
1536 #endif
1537
1538         while (waitpid(pmonitor->m_pid, &status, 0) == -1)
1539                 if (errno != EINTR)
1540                         exit(1);
1541
1542         res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
1543
1544         /* Terminate process */
1545         exit(res);
1546 }
1547
1548 #ifdef SSH_AUDIT_EVENTS
1549 /* Report that an audit event occurred */
1550 int
1551 mm_answer_audit_event(int socket, Buffer *m)
1552 {
1553         ssh_audit_event_t event;
1554
1555         debug3("%s entering", __func__);
1556
1557         event = buffer_get_int(m);
1558         switch(event) {
1559         case SSH_AUTH_FAIL_PUBKEY:
1560         case SSH_AUTH_FAIL_HOSTBASED:
1561         case SSH_AUTH_FAIL_GSSAPI:
1562         case SSH_LOGIN_EXCEED_MAXTRIES:
1563         case SSH_LOGIN_ROOT_DENIED:
1564         case SSH_CONNECTION_CLOSE:
1565         case SSH_INVALID_USER:
1566                 audit_event(event);
1567                 break;
1568         default:
1569                 fatal("Audit event type %d not permitted", event);
1570         }
1571
1572         return (0);
1573 }
1574
1575 int
1576 mm_answer_audit_command(int socket, Buffer *m)
1577 {
1578         u_int len;
1579         char *cmd;
1580
1581         debug3("%s entering", __func__);
1582         cmd = buffer_get_string(m, &len);
1583         /* sanity check command, if so how? */
1584         audit_run_command(cmd);
1585         free(cmd);
1586         return (0);
1587 }
1588 #endif /* SSH_AUDIT_EVENTS */
1589
1590 void
1591 monitor_clear_keystate(struct monitor *pmonitor)
1592 {
1593         struct ssh *ssh = active_state; /* XXX */
1594
1595         ssh_clear_newkeys(ssh, MODE_IN);
1596         ssh_clear_newkeys(ssh, MODE_OUT);
1597         sshbuf_free(child_state);
1598         child_state = NULL;
1599 }
1600
1601 void
1602 monitor_apply_keystate(struct monitor *pmonitor)
1603 {
1604         struct ssh *ssh = active_state; /* XXX */
1605         struct kex *kex;
1606         int r;
1607
1608         debug3("%s: packet_set_state", __func__);
1609         if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
1610                 fatal("%s: packet_set_state: %s", __func__, ssh_err(r));
1611         sshbuf_free(child_state);
1612         child_state = NULL;
1613
1614         if ((kex = ssh->kex) != NULL) {
1615                 /* XXX set callbacks */
1616 #ifdef WITH_OPENSSL
1617                 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1618                 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1619                 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
1620                 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
1621                 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
1622                 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1623                 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1624 # ifdef OPENSSL_HAS_ECC
1625                 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
1626 # endif
1627 #endif /* WITH_OPENSSL */
1628                 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
1629                 kex->load_host_public_key=&get_hostkey_public_by_type;
1630                 kex->load_host_private_key=&get_hostkey_private_by_type;
1631                 kex->host_key_index=&get_hostkey_index;
1632                 kex->sign = sshd_hostkey_sign;
1633         }
1634 }
1635
1636 /* This function requries careful sanity checking */
1637
1638 void
1639 mm_get_keystate(struct monitor *pmonitor)
1640 {
1641         debug3("%s: Waiting for new keys", __func__);
1642
1643         if ((child_state = sshbuf_new()) == NULL)
1644                 fatal("%s: sshbuf_new failed", __func__);
1645         mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
1646             child_state);
1647         debug3("%s: GOT new keys", __func__);
1648 }
1649
1650
1651 /* XXX */
1652
1653 #define FD_CLOSEONEXEC(x) do { \
1654         if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
1655                 fatal("fcntl(%d, F_SETFD)", x); \
1656 } while (0)
1657
1658 static void
1659 monitor_openfds(struct monitor *mon, int do_logfds)
1660 {
1661         int pair[2];
1662 #ifdef SO_ZEROIZE
1663         int on = 1;
1664 #endif
1665
1666         if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
1667                 fatal("%s: socketpair: %s", __func__, strerror(errno));
1668 #ifdef SO_ZEROIZE
1669         if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0)
1670                 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
1671         if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0)
1672                 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
1673 #endif
1674         FD_CLOSEONEXEC(pair[0]);
1675         FD_CLOSEONEXEC(pair[1]);
1676         mon->m_recvfd = pair[0];
1677         mon->m_sendfd = pair[1];
1678
1679         if (do_logfds) {
1680                 if (pipe(pair) == -1)
1681                         fatal("%s: pipe: %s", __func__, strerror(errno));
1682                 FD_CLOSEONEXEC(pair[0]);
1683                 FD_CLOSEONEXEC(pair[1]);
1684                 mon->m_log_recvfd = pair[0];
1685                 mon->m_log_sendfd = pair[1];
1686         } else
1687                 mon->m_log_recvfd = mon->m_log_sendfd = -1;
1688 }
1689
1690 #define MM_MEMSIZE      65536
1691
1692 struct monitor *
1693 monitor_init(void)
1694 {
1695         struct monitor *mon;
1696
1697         mon = xcalloc(1, sizeof(*mon));
1698         monitor_openfds(mon, 1);
1699
1700         return mon;
1701 }
1702
1703 void
1704 monitor_reinit(struct monitor *mon)
1705 {
1706         monitor_openfds(mon, 0);
1707 }
1708
1709 #ifdef GSSAPI
1710 int
1711 mm_answer_gss_setup_ctx(int sock, Buffer *m)
1712 {
1713         gss_OID_desc goid;
1714         OM_uint32 major;
1715         u_int len;
1716
1717         if (!options.gss_authentication)
1718                 fatal("%s: GSSAPI authentication not enabled", __func__);
1719
1720         goid.elements = buffer_get_string(m, &len);
1721         goid.length = len;
1722
1723         major = ssh_gssapi_server_ctx(&gsscontext, &goid);
1724
1725         free(goid.elements);
1726
1727         buffer_clear(m);
1728         buffer_put_int(m, major);
1729
1730         mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
1731
1732         /* Now we have a context, enable the step */
1733         monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
1734
1735         return (0);
1736 }
1737
1738 int
1739 mm_answer_gss_accept_ctx(int sock, Buffer *m)
1740 {
1741         gss_buffer_desc in;
1742         gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
1743         OM_uint32 major, minor;
1744         OM_uint32 flags = 0; /* GSI needs this */
1745         u_int len;
1746
1747         if (!options.gss_authentication)
1748                 fatal("%s: GSSAPI authentication not enabled", __func__);
1749
1750         in.value = buffer_get_string(m, &len);
1751         in.length = len;
1752         major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
1753         free(in.value);
1754
1755         buffer_clear(m);
1756         buffer_put_int(m, major);
1757         buffer_put_string(m, out.value, out.length);
1758         buffer_put_int(m, flags);
1759         mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
1760
1761         gss_release_buffer(&minor, &out);
1762
1763         if (major == GSS_S_COMPLETE) {
1764                 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
1765                 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1766                 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
1767         }
1768         return (0);
1769 }
1770
1771 int
1772 mm_answer_gss_checkmic(int sock, Buffer *m)
1773 {
1774         gss_buffer_desc gssbuf, mic;
1775         OM_uint32 ret;
1776         u_int len;
1777
1778         if (!options.gss_authentication)
1779                 fatal("%s: GSSAPI authentication not enabled", __func__);
1780
1781         gssbuf.value = buffer_get_string(m, &len);
1782         gssbuf.length = len;
1783         mic.value = buffer_get_string(m, &len);
1784         mic.length = len;
1785
1786         ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
1787
1788         free(gssbuf.value);
1789         free(mic.value);
1790
1791         buffer_clear(m);
1792         buffer_put_int(m, ret);
1793
1794         mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
1795
1796         if (!GSS_ERROR(ret))
1797                 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1798
1799         return (0);
1800 }
1801
1802 int
1803 mm_answer_gss_userok(int sock, Buffer *m)
1804 {
1805         int authenticated;
1806         const char *displayname;
1807
1808         if (!options.gss_authentication)
1809                 fatal("%s: GSSAPI authentication not enabled", __func__);
1810
1811         authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
1812
1813         buffer_clear(m);
1814         buffer_put_int(m, authenticated);
1815
1816         debug3("%s: sending result %d", __func__, authenticated);
1817         mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
1818
1819         auth_method = "gssapi-with-mic";
1820
1821         if ((displayname = ssh_gssapi_displayname()) != NULL)
1822                 auth2_record_info(authctxt, "%s", displayname);
1823
1824         /* Monitor loop will terminate if authenticated */
1825         return (authenticated);
1826 }
1827 #endif /* GSSAPI */
1828