granicus.if.org Git - postgresql/blob - src/backend/libpq/auth.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * auth.c
   4  *        Routines to handle network authentication
   5  *
   6  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/libpq/auth.c,v 1.100 2003/04/22 00:08:06 tgl Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15
  16 #include "postgres.h"
  17
  18 #include <sys/param.h>
  19 #include <sys/socket.h>
  20 #if defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
  21 #include <sys/uio.h>
  22 #include <sys/ucred.h>
  23 #include <errno.h>
  24 #endif
  25 #include <netinet/in.h>
  26 #include <arpa/inet.h>
  27
  28 #include "libpq/auth.h"
  29 #include "libpq/crypt.h"
  30 #include "libpq/hba.h"
  31 #include "libpq/libpq.h"
  32 #include "libpq/pqcomm.h"
  33 #include "libpq/pqformat.h"
  34 #include "miscadmin.h"
  35 #include "storage/ipc.h"
  36
  37
  38 static void sendAuthRequest(Port *port, AuthRequest areq);
  39 static void auth_failed(Port *port, int status);
  40 static char *recv_password_packet(Port *port);
  41 static int      recv_and_check_password_packet(Port *port);
  42
  43 char       *pg_krb_server_keyfile;
  44
  45 #ifdef USE_PAM
  46 #ifdef HAVE_PAM_PAM_APPL_H
  47 #include <pam/pam_appl.h>
  48 #endif
  49 #ifdef HAVE_SECURITY_PAM_APPL_H
  50 #include <security/pam_appl.h>
  51 #endif
  52
  53 #define PGSQL_PAM_SERVICE "postgresql"  /* Service name passed to PAM */
  54
  55 static int      CheckPAMAuth(Port *port, char *user, char *password);
  56 static int pam_passwd_conv_proc(int num_msg, const struct pam_message ** msg,
  57                                          struct pam_response ** resp, void *appdata_ptr);
  58
  59 static struct pam_conv pam_passw_conv = {
  60         &pam_passwd_conv_proc,
  61         NULL
  62 };
  63
  64 static char *pam_passwd = NULL; /* Workaround for Solaris 2.6 brokenness */
  65 static Port *pam_port_cludge;   /* Workaround for passing "Port *port"
  66                                                                  * into pam_passwd_conv_proc */
  67 #endif   /* USE_PAM */
  68
  69 #ifdef KRB4
  70 /*----------------------------------------------------------------
  71  * MIT Kerberos authentication system - protocol version 4
  72  *----------------------------------------------------------------
  73  */
  74
  75 #include "krb.h"
  76
  77 /*
  78  * pg_krb4_recvauth -- server routine to receive authentication information
  79  *                                         from the client
  80  *
  81  * Nothing unusual here, except that we compare the username obtained from
  82  * the client's setup packet to the authenticated name.  (We have to retain
  83  * the name in the setup packet since we have to retain the ability to handle
  84  * unauthenticated connections.)
  85  */
  86 static int
  87 pg_krb4_recvauth(Port *port)
  88 {
  89         long            krbopts = 0;    /* one-way authentication */
  90         KTEXT_ST        clttkt;
  91         char            instance[INST_SZ + 1],
  92                                 version[KRB_SENDAUTH_VLEN + 1];
  93         AUTH_DAT        auth_data;
  94         Key_schedule key_sched;
  95         int                     status;
  96
  97         strcpy(instance, "*");          /* don't care, but arg gets expanded
  98                                                                  * anyway */
  99         status = krb_recvauth(krbopts,
 100                                                   port->sock,
 101                                                   &clttkt,
 102                                                   PG_KRB_SRVNAM,
 103                                                   instance,
 104                                                   &port->raddr.in,
 105                                                   &port->laddr.in,
 106                                                   &auth_data,
 107                                                   pg_krb_server_keyfile,
 108                                                   key_sched,
 109                                                   version);
 110         if (status != KSUCCESS)
 111         {
 112                 elog(LOG, "pg_krb4_recvauth: kerberos error: %s",
 113                          krb_err_txt[status]);
 114                 return STATUS_ERROR;
 115         }
 116         if (strncmp(version, PG_KRB4_VERSION, KRB_SENDAUTH_VLEN) != 0)
 117         {
 118                 elog(LOG, "pg_krb4_recvauth: protocol version \"%s\" != \"%s\"",
 119                          version, PG_KRB4_VERSION);
 120                 return STATUS_ERROR;
 121         }
 122         if (strncmp(port->user, auth_data.pname, SM_DATABASE_USER) != 0)
 123         {
 124                 elog(LOG, "pg_krb4_recvauth: name \"%s\" != \"%s\"",
 125                          port->user, auth_data.pname);
 126                 return STATUS_ERROR;
 127         }
 128         return STATUS_OK;
 129 }
 130
 131 #else
 132
 133 static int
 134 pg_krb4_recvauth(Port *port)
 135 {
 136         elog(LOG, "pg_krb4_recvauth: Kerberos not implemented on this server");
 137         return STATUS_ERROR;
 138 }
 139 #endif   /* KRB4 */
 140
 141
 142 #ifdef KRB5
 143 /*----------------------------------------------------------------
 144  * MIT Kerberos authentication system - protocol version 5
 145  *----------------------------------------------------------------
 146  */
 147
 148 #include <krb5.h>
 149 #include <com_err.h>
 150
 151 /*
 152  * pg_an_to_ln -- return the local name corresponding to an authentication
 153  *                                name
 154  *
 155  * XXX Assumes that the first aname component is the user name.  This is NOT
 156  *         necessarily so, since an aname can actually be something out of your
 157  *         worst X.400 nightmare, like
 158  *                ORGANIZATION=U. C. Berkeley/NAME=Paul M. Aoki@CS.BERKELEY.EDU
 159  *         Note that the MIT an_to_ln code does the same thing if you don't
 160  *         provide an aname mapping database...it may be a better idea to use
 161  *         krb5_an_to_ln, except that it punts if multiple components are found,
 162  *         and we can't afford to punt.
 163  */
 164 static char *
 165 pg_an_to_ln(char *aname)
 166 {
 167         char       *p;
 168
 169         if ((p = strchr(aname, '/')) || (p = strchr(aname, '@')))
 170                 *p = '\0';
 171         return aname;
 172 }
 173
 174
 175 /*
 176  * Various krb5 state which is not connection specfic, and a flag to
 177  * indicate whether we have initialised it yet.
 178  */
 179 static int      pg_krb5_initialised;
 180 static krb5_context pg_krb5_context;
 181 static krb5_keytab pg_krb5_keytab;
 182 static krb5_principal pg_krb5_server;
 183
 184
 185 static int
 186 pg_krb5_init(void)
 187 {
 188         krb5_error_code retval;
 189
 190         if (pg_krb5_initialised)
 191                 return STATUS_OK;
 192
 193         retval = krb5_init_context(&pg_krb5_context);
 194         if (retval)
 195         {
 196                 elog(LOG, "pg_krb5_init: krb5_init_context returned Kerberos error %d",
 197                          retval);
 198                 com_err("postgres", retval, "while initializing krb5");
 199                 return STATUS_ERROR;
 200         }
 201
 202         retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab);
 203         if (retval)
 204         {
 205                 elog(LOG, "pg_krb5_init: krb5_kt_resolve returned Kerberos error %d",
 206                          retval);
 207                 com_err("postgres", retval, "while resolving keytab file %s",
 208                                 pg_krb_server_keyfile);
 209                 krb5_free_context(pg_krb5_context);
 210                 return STATUS_ERROR;
 211         }
 212
 213         retval = krb5_sname_to_principal(pg_krb5_context, NULL, PG_KRB_SRVNAM,
 214                                                                          KRB5_NT_SRV_HST, &pg_krb5_server);
 215         if (retval)
 216         {
 217                 elog(LOG, "pg_krb5_init: krb5_sname_to_principal returned Kerberos error %d",
 218                          retval);
 219                 com_err("postgres", retval,
 220                                 "while getting server principal for service %s",
 221                                 PG_KRB_SRVNAM);
 222                 krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
 223                 krb5_free_context(pg_krb5_context);
 224                 return STATUS_ERROR;
 225         }
 226
 227         pg_krb5_initialised = 1;
 228         return STATUS_OK;
 229 }
 230
 231
 232 /*
 233  * pg_krb5_recvauth -- server routine to receive authentication information
 234  *                                         from the client
 235  *
 236  * We still need to compare the username obtained from the client's setup
 237  * packet to the authenticated name, as described in pg_krb4_recvauth.  This
 238  * is a bit more problematic in v5, as described above in pg_an_to_ln.
 239  *
 240  * We have our own keytab file because postgres is unlikely to run as root,
 241  * and so cannot read the default keytab.
 242  */
 243 static int
 244 pg_krb5_recvauth(Port *port)
 245 {
 246         krb5_error_code retval;
 247         int                     ret;
 248         krb5_auth_context auth_context = NULL;
 249         krb5_ticket *ticket;
 250         char       *kusername;
 251
 252         ret = pg_krb5_init();
 253         if (ret != STATUS_OK)
 254                 return ret;
 255
 256         retval = krb5_recvauth(pg_krb5_context, &auth_context,
 257                                                    (krb5_pointer) & port->sock, PG_KRB_SRVNAM,
 258                                                    pg_krb5_server, 0, pg_krb5_keytab, &ticket);
 259         if (retval)
 260         {
 261                 elog(LOG, "pg_krb5_recvauth: krb5_recvauth returned Kerberos error %d",
 262                          retval);
 263                 com_err("postgres", retval, "from krb5_recvauth");
 264                 return STATUS_ERROR;
 265         }
 266
 267         /*
 268          * The "client" structure comes out of the ticket and is therefore
 269          * authenticated.  Use it to check the username obtained from the
 270          * postmaster startup packet.
 271          *
 272          * I have no idea why this is considered necessary.
 273          */
 274 #if defined(HAVE_KRB5_TICKET_ENC_PART2)
 275         retval = krb5_unparse_name(pg_krb5_context,
 276                                                            ticket->enc_part2->client, &kusername);
 277 #elif defined(HAVE_KRB5_TICKET_CLIENT)
 278         retval = krb5_unparse_name(pg_krb5_context,
 279                                                            ticket->client, &kusername);
 280 #else
 281 #error "bogus configuration"
 282 #endif
 283         if (retval)
 284         {
 285                 elog(LOG, "pg_krb5_recvauth: krb5_unparse_name returned Kerberos error %d",
 286                          retval);
 287                 com_err("postgres", retval, "while unparsing client name");
 288                 krb5_free_ticket(pg_krb5_context, ticket);
 289                 krb5_auth_con_free(pg_krb5_context, auth_context);
 290                 return STATUS_ERROR;
 291         }
 292
 293         kusername = pg_an_to_ln(kusername);
 294         if (strncmp(port->user, kusername, SM_DATABASE_USER))
 295         {
 296                 elog(LOG, "pg_krb5_recvauth: user name \"%s\" != krb5 name \"%s\"",
 297                          port->user, kusername);
 298                 ret = STATUS_ERROR;
 299         }
 300         else
 301                 ret = STATUS_OK;
 302
 303         krb5_free_ticket(pg_krb5_context, ticket);
 304         krb5_auth_con_free(pg_krb5_context, auth_context);
 305         free(kusername);
 306
 307         return ret;
 308 }
 309
 310 #else
 311
 312 static int
 313 pg_krb5_recvauth(Port *port)
 314 {
 315         elog(LOG, "pg_krb5_recvauth: Kerberos not implemented on this server");
 316         return STATUS_ERROR;
 317 }
 318 #endif   /* KRB5 */
 319
 320
 321 /*
 322  * Tell the user the authentication failed, but not (much about) why.
 323  *
 324  * There is a tradeoff here between security concerns and making life
 325  * unnecessarily difficult for legitimate users.  We would not, for example,
 326  * want to report the password we were expecting to receive...
 327  * But it seems useful to report the username and authorization method
 328  * in use, and these are items that must be presumed known to an attacker
 329  * anyway.
 330  * Note that many sorts of failure report additional information in the
 331  * postmaster log, which we hope is only readable by good guys.
 332  */
 333 static void
 334 auth_failed(Port *port, int status)
 335 {
 336         const char *authmethod = "Unknown auth method:";
 337
 338         /*
 339          * If we failed due to EOF from client, just quit; there's no point in
 340          * trying to send a message to the client, and not much point in
 341          * logging the failure in the postmaster log.  (Logging the failure
 342          * might be desirable, were it not for the fact that libpq closes the
 343          * connection unceremoniously if challenged for a password when it
 344          * hasn't got one to send.  We'll get a useless log entry for every
 345          * psql connection under password auth, even if it's perfectly
 346          * successful, if we log STATUS_EOF events.)
 347          */
 348         if (status == STATUS_EOF)
 349                 proc_exit(0);
 350
 351         switch (port->auth_method)
 352         {
 353                 case uaReject:
 354                         authmethod = "Rejected host:";
 355                         break;
 356                 case uaKrb4:
 357                         authmethod = "Kerberos4";
 358                         break;
 359                 case uaKrb5:
 360                         authmethod = "Kerberos5";
 361                         break;
 362                 case uaTrust:
 363                         authmethod = "Trusted";
 364                         break;
 365                 case uaIdent:
 366                         authmethod = "IDENT";
 367                         break;
 368                 case uaMD5:
 369                 case uaCrypt:
 370                 case uaPassword:
 371                         authmethod = "Password";
 372                         break;
 373 #ifdef USE_PAM
 374                 case uaPAM:
 375                         authmethod = "PAM";
 376                         break;
 377 #endif   /* USE_PAM */
 378         }
 379
 380         elog(FATAL, "%s authentication failed for user \"%s\"",
 381                  authmethod, port->user_name);
 382         /* doesn't return */
 383 }
 384
 385
 386 /*
 387  * Client authentication starts here.  If there is an error, this
 388  * function does not return and the backend process is terminated.
 389  */
 390 void
 391 ClientAuthentication(Port *port)
 392 {
 393         int                     status = STATUS_ERROR;
 394
 395         /*
 396          * Get the authentication method to use for this frontend/database
 397          * combination.  Note: a failure return indicates a problem with the
 398          * hba config file, not with the request.  hba.c should have dropped
 399          * an error message into the postmaster logfile if it failed.
 400          */
 401         if (hba_getauthmethod(port) != STATUS_OK)
 402                 elog(FATAL, "Missing or erroneous pg_hba.conf file, see postmaster log for details");
 403
 404         switch (port->auth_method)
 405         {
 406                 case uaReject:
 407
 408                         /*
 409                          * This could have come from an explicit "reject" entry in
 410                          * pg_hba.conf, but more likely it means there was no matching
 411                          * entry.  Take pity on the poor user and issue a helpful
 412                          * error message.  NOTE: this is not a security breach,
 413                          * because all the info reported here is known at the frontend
 414                          * and must be assumed known to bad guys. We're merely helping
 415                          * out the less clueful good guys.
 416                          */
 417                         {
 418                                 const char *hostinfo = "localhost";
 419 #ifdef HAVE_IPV6
 420                                 char    ip_hostinfo[INET6_ADDRSTRLEN];
 421 #else
 422                                 char    ip_hostinfo[INET_ADDRSTRLEN];
 423 #endif
 424                                 if (isAF_INETx(port->raddr.sa.sa_family) )
 425                                         hostinfo = SockAddr_ntop(&port->raddr, ip_hostinfo,
 426                                                            sizeof(ip_hostinfo), 1);
 427
 428                                 elog(FATAL,
 429                                         "No pg_hba.conf entry for host %s, user %s, database %s",
 430                                         hostinfo, port->user_name, port->database_name);
 431                                 break;
 432                         }
 433
 434                 case uaKrb4:
 435                         sendAuthRequest(port, AUTH_REQ_KRB4);
 436                         status = pg_krb4_recvauth(port);
 437                         break;
 438
 439                 case uaKrb5:
 440                         sendAuthRequest(port, AUTH_REQ_KRB5);
 441                         status = pg_krb5_recvauth(port);
 442                         break;
 443
 444                 case uaIdent:
 445 #if defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || \
 446         (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS)) && \
 447         !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED)
 448
 449                         /*
 450                          * If we are doing ident on unix-domain sockets, use SCM_CREDS
 451                          * only if it is defined and SO_PEERCRED isn't.
 452                          */
 453 #if defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
 454
 455                         /*
 456                          * Receive credentials on next message receipt, BSD/OS,
 457                          * NetBSD. We need to set this before the client sends the
 458                          * next packet.
 459                          */
 460                         {
 461                                 int                     on = 1;
 462
 463                                 if (setsockopt(port->sock, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
 464                                         elog(FATAL, "pg_local_sendauth: can't do setsockopt: %m");
 465                         }
 466 #endif
 467                         if (port->raddr.sa.sa_family == AF_UNIX)
 468                                 sendAuthRequest(port, AUTH_REQ_SCM_CREDS);
 469 #endif
 470                         status = authident(port);
 471                         break;
 472
 473                 case uaMD5:
 474                         sendAuthRequest(port, AUTH_REQ_MD5);
 475                         status = recv_and_check_password_packet(port);
 476                         break;
 477
 478                 case uaCrypt:
 479                         sendAuthRequest(port, AUTH_REQ_CRYPT);
 480                         status = recv_and_check_password_packet(port);
 481                         break;
 482
 483                 case uaPassword:
 484                         sendAuthRequest(port, AUTH_REQ_PASSWORD);
 485                         status = recv_and_check_password_packet(port);
 486                         break;
 487
 488 #ifdef USE_PAM
 489                 case uaPAM:
 490                         pam_port_cludge = port;
 491                         status = CheckPAMAuth(port, port->user, "");
 492                         break;
 493 #endif   /* USE_PAM */
 494
 495                 case uaTrust:
 496                         status = STATUS_OK;
 497                         break;
 498         }
 499
 500         if (status == STATUS_OK)
 501                 sendAuthRequest(port, AUTH_REQ_OK);
 502         else
 503                 auth_failed(port, status);
 504 }
 505
 506
 507 /*
 508  * Send an authentication request packet to the frontend.
 509  */
 510 static void
 511 sendAuthRequest(Port *port, AuthRequest areq)
 512 {
 513         StringInfoData buf;
 514
 515         pq_beginmessage(&buf, 'R');
 516         pq_sendint(&buf, (int32) areq, sizeof(int32));
 517
 518         /* Add the salt for encrypted passwords. */
 519         if (areq == AUTH_REQ_MD5)
 520                 pq_sendbytes(&buf, port->md5Salt, 4);
 521         else if (areq == AUTH_REQ_CRYPT)
 522                 pq_sendbytes(&buf, port->cryptSalt, 2);
 523
 524         pq_endmessage(&buf);
 525
 526         /*
 527          * Flush message so client will see it, except for AUTH_REQ_OK, which
 528          * need not be sent until we are ready for queries.
 529          */
 530         if (areq != AUTH_REQ_OK)
 531                 pq_flush();
 532 }
 533
 534
 535 #ifdef USE_PAM
 536
 537 /*
 538  * PAM conversation function
 539  */
 540
 541 static int
 542 pam_passwd_conv_proc(int num_msg, const struct pam_message ** msg,
 543                                          struct pam_response ** resp, void *appdata_ptr)
 544 {
 545         if (num_msg != 1 || msg[0]->msg_style != PAM_PROMPT_ECHO_OFF)
 546         {
 547                 switch (msg[0]->msg_style)
 548                 {
 549                         case PAM_ERROR_MSG:
 550                                 elog(LOG, "pam_passwd_conv_proc: Error from underlying PAM layer: '%s'",
 551                                          msg[0]->msg);
 552                                 return PAM_CONV_ERR;
 553                         default:
 554                                 elog(LOG, "pam_passwd_conv_proc: Unexpected PAM conversation %d/'%s'",
 555                                          msg[0]->msg_style, msg[0]->msg);
 556                                 return PAM_CONV_ERR;
 557                 }
 558         }
 559
 560         if (!appdata_ptr)
 561         {
 562                 /*
 563                  * Workaround for Solaris 2.6 where the PAM library is broken and
 564                  * does not pass appdata_ptr to the conversation routine
 565                  */
 566                 appdata_ptr = pam_passwd;
 567         }
 568
 569         /*
 570          * Password wasn't passed to PAM the first time around - let's go ask
 571          * the client to send a password, which we then stuff into PAM.
 572          */
 573         if (strlen(appdata_ptr) == 0)
 574         {
 575                 char       *passwd;
 576
 577                 sendAuthRequest(pam_port_cludge, AUTH_REQ_PASSWORD);
 578                 passwd = recv_password_packet(pam_port_cludge);
 579
 580                 if (passwd == NULL)
 581                         return PAM_CONV_ERR;    /* client didn't want to send password */
 582
 583                 if (strlen(passwd) == 0)
 584                 {
 585                         elog(LOG, "pam_passwd_conv_proc: no password");
 586                         return PAM_CONV_ERR;
 587                 }
 588                 appdata_ptr = passwd;
 589         }
 590
 591         /*
 592          * Explicitly not using palloc here - PAM will free this memory in
 593          * pam_end()
 594          */
 595         *resp = calloc(num_msg, sizeof(struct pam_response));
 596         if (!*resp)
 597         {
 598                 elog(LOG, "pam_passwd_conv_proc: Out of memory!");
 599                 return PAM_CONV_ERR;
 600         }
 601
 602         (*resp)[0].resp = strdup((char *) appdata_ptr);
 603         (*resp)[0].resp_retcode = 0;
 604
 605         return ((*resp)[0].resp ? PAM_SUCCESS : PAM_CONV_ERR);
 606 }
 607
 608
 609 /*
 610  * Check authentication against PAM.
 611  */
 612 static int
 613 CheckPAMAuth(Port *port, char *user, char *password)
 614 {
 615         int                     retval;
 616         pam_handle_t *pamh = NULL;
 617
 618         /*
 619          * Apparently, Solaris 2.6 is broken, and needs ugly static variable
 620          * workaround
 621          */
 622         pam_passwd = password;
 623
 624         /*
 625          * Set the application data portion of the conversation struct This is
 626          * later used inside the PAM conversation to pass the password to the
 627          * authentication module.
 628          */
 629         pam_passw_conv.appdata_ptr = (char *) password;         /* from password above,
 630                                                                                                                  * not allocated */
 631
 632         /* Optionally, one can set the service name in pg_hba.conf */
 633         if (port->auth_arg && port->auth_arg[0] != '\0')
 634                 retval = pam_start(port->auth_arg, "pgsql@",
 635                                                    &pam_passw_conv, &pamh);
 636         else
 637                 retval = pam_start(PGSQL_PAM_SERVICE, "pgsql@",
 638                                                    &pam_passw_conv, &pamh);
 639
 640         if (retval != PAM_SUCCESS)
 641         {
 642                 elog(LOG, "CheckPAMAuth: Failed to create PAM authenticator: '%s'",
 643                          pam_strerror(pamh, retval));
 644                 pam_passwd = NULL;              /* Unset pam_passwd */
 645                 return STATUS_ERROR;
 646         }
 647
 648         retval = pam_set_item(pamh, PAM_USER, user);
 649
 650         if (retval != PAM_SUCCESS)
 651         {
 652                 elog(LOG, "CheckPAMAuth: pam_set_item(PAM_USER) failed: '%s'",
 653                          pam_strerror(pamh, retval));
 654                 pam_passwd = NULL;              /* Unset pam_passwd */
 655                 return STATUS_ERROR;
 656         }
 657
 658         retval = pam_set_item(pamh, PAM_CONV, &pam_passw_conv);
 659
 660         if (retval != PAM_SUCCESS)
 661         {
 662                 elog(LOG, "CheckPAMAuth: pam_set_item(PAM_CONV) failed: '%s'",
 663                          pam_strerror(pamh, retval));
 664                 pam_passwd = NULL;              /* Unset pam_passwd */
 665                 return STATUS_ERROR;
 666         }
 667
 668         retval = pam_authenticate(pamh, 0);
 669
 670         if (retval != PAM_SUCCESS)
 671         {
 672                 elog(LOG, "CheckPAMAuth: pam_authenticate failed: '%s'",
 673                          pam_strerror(pamh, retval));
 674                 pam_passwd = NULL;              /* Unset pam_passwd */
 675                 return STATUS_ERROR;
 676         }
 677
 678         retval = pam_acct_mgmt(pamh, 0);
 679
 680         if (retval != PAM_SUCCESS)
 681         {
 682                 elog(LOG, "CheckPAMAuth: pam_acct_mgmt failed: '%s'",
 683                          pam_strerror(pamh, retval));
 684                 pam_passwd = NULL;              /* Unset pam_passwd */
 685                 return STATUS_ERROR;
 686         }
 687
 688         retval = pam_end(pamh, retval);
 689
 690         if (retval != PAM_SUCCESS)
 691         {
 692                 elog(LOG, "CheckPAMAuth: Failed to release PAM authenticator: '%s'",
 693                          pam_strerror(pamh, retval));
 694         }
 695
 696         pam_passwd = NULL;                      /* Unset pam_passwd */
 697
 698         return (retval == PAM_SUCCESS ? STATUS_OK : STATUS_ERROR);
 699 }
 700 #endif   /* USE_PAM */
 701
 702
 703 /*
 704  * Collect password response packet from frontend.
 705  *
 706  * Returns NULL if couldn't get password, else palloc'd string.
 707  */
 708 static char *
 709 recv_password_packet(Port *port)
 710 {
 711         StringInfoData buf;
 712
 713         if (PG_PROTOCOL_MAJOR(port->proto) >= 3)
 714         {
 715                 /* Expect 'p' message type */
 716                 int             mtype;
 717
 718                 mtype = pq_getbyte();
 719                 if (mtype != 'p')
 720                 {
 721                         /*
 722                          * If the client just disconnects without offering a password,
 723                          * don't make a log entry.  This is legal per protocol spec and
 724                          * in fact commonly done by psql, so complaining just clutters
 725                          * the log.
 726                          */
 727                         if (mtype != EOF)
 728                                 elog(COMMERROR, "Expected password response, got %c", mtype);
 729                         return NULL;            /* EOF or bad message type */
 730                 }
 731         }
 732         else
 733         {
 734                 /* For pre-3.0 clients, avoid log entry if they just disconnect */
 735                 if (pq_peekbyte() == EOF)
 736                         return NULL;            /* EOF */
 737         }
 738
 739         initStringInfo(&buf);
 740         if (pq_getmessage(&buf, 1000)) /* receive password */
 741         {
 742                 /* EOF - pq_getmessage already logged a suitable message */
 743                 pfree(buf.data);
 744                 return NULL;
 745         }
 746
 747         /*
 748          * Apply sanity check: password packet length should agree with length
 749          * of contained string.  Note it is safe to use strlen here because
 750          * StringInfo is guaranteed to have an appended '\0'.
 751          */
 752         if (strlen(buf.data) + 1 != buf.len)
 753                 elog(COMMERROR, "bogus password packet size");
 754
 755         /* Do not echo password to logs, for security. */
 756         elog(DEBUG5, "received password packet");
 757
 758         /*
 759          * Return the received string.  Note we do not attempt to do any
 760          * character-set conversion on it; since we don't yet know the
 761          * client's encoding, there wouldn't be much point.
 762          */
 763         return buf.data;
 764 }
 765
 766
 767 /*
 768  * Called when we have sent an authorization request for a password.
 769  * Get the response and check it.
 770  */
 771 static int
 772 recv_and_check_password_packet(Port *port)
 773 {
 774         char       *passwd;
 775         int                     result;
 776
 777         passwd = recv_password_packet(port);
 778
 779         if (passwd == NULL)
 780                 return STATUS_EOF;              /* client wouldn't send password */
 781
 782         result = md5_crypt_verify(port, port->user_name, passwd);
 783
 784         pfree(passwd);
 785
 786         return result;
 787 }