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) 1996-2004, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL: pgsql/src/backend/libpq/auth.c,v 1.120 2004/12/20 17:13:40 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                 ereport(LOG,
 113                                 (errmsg("Kerberos error: %s", krb_err_txt[status])));
 114                 return STATUS_ERROR;
 115         }
 116         if (strncmp(version, PG_KRB4_VERSION, KRB_SENDAUTH_VLEN) != 0)
 117         {
 118                 ereport(LOG,
 119                                 (errmsg("unexpected Kerberos protocol version received from client (received \"%s\", expected \"%s\")",
 120                                                 version, PG_KRB4_VERSION)));
 121                 return STATUS_ERROR;
 122         }
 123         if (strncmp(port->user_name, auth_data.pname, SM_DATABASE_USER) != 0)
 124         {
 125                 ereport(LOG,
 126                                 (errmsg("unexpected Kerberos user name received from client (received \"%s\", expected \"%s\")",
 127                                                 port->user_name, auth_data.pname)));
 128                 return STATUS_ERROR;
 129         }
 130         return STATUS_OK;
 131 }
 132
 133 #else
 134
 135 static int
 136 pg_krb4_recvauth(Port *port)
 137 {
 138         ereport(LOG,
 139                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 140                          errmsg("Kerberos 4 not implemented on this server")));
 141         return STATUS_ERROR;
 142 }
 143 #endif   /* KRB4 */
 144
 145
 146 #ifdef KRB5
 147 /*----------------------------------------------------------------
 148  * MIT Kerberos authentication system - protocol version 5
 149  *----------------------------------------------------------------
 150  */
 151
 152 #include <krb5.h>
 153
 154 /*
 155  * pg_an_to_ln -- return the local name corresponding to an authentication
 156  *                                name
 157  *
 158  * XXX Assumes that the first aname component is the user name.  This is NOT
 159  *         necessarily so, since an aname can actually be something out of your
 160  *         worst X.400 nightmare, like
 161  *                ORGANIZATION=U. C. Berkeley/NAME=Paul M. Aoki@CS.BERKELEY.EDU
 162  *         Note that the MIT an_to_ln code does the same thing if you don't
 163  *         provide an aname mapping database...it may be a better idea to use
 164  *         krb5_an_to_ln, except that it punts if multiple components are found,
 165  *         and we can't afford to punt.
 166  */
 167 static char *
 168 pg_an_to_ln(char *aname)
 169 {
 170         char       *p;
 171
 172         if ((p = strchr(aname, '/')) || (p = strchr(aname, '@')))
 173                 *p = '\0';
 174         return aname;
 175 }
 176
 177
 178 /*
 179  * Various krb5 state which is not connection specfic, and a flag to
 180  * indicate whether we have initialised it yet.
 181  */
 182 static int      pg_krb5_initialised;
 183 static krb5_context pg_krb5_context;
 184 static krb5_keytab pg_krb5_keytab;
 185 static krb5_principal pg_krb5_server;
 186
 187
 188 static int
 189 pg_krb5_init(void)
 190 {
 191         krb5_error_code retval;
 192
 193         if (pg_krb5_initialised)
 194                 return STATUS_OK;
 195
 196         retval = krb5_init_context(&pg_krb5_context);
 197         if (retval)
 198         {
 199                 ereport(LOG,
 200                                 (errmsg("Kerberos initialization returned error %d",
 201                                                 retval)));
 202                 com_err("postgres", retval, "while initializing krb5");
 203                 return STATUS_ERROR;
 204         }
 205
 206         retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab);
 207         if (retval)
 208         {
 209                 ereport(LOG,
 210                                 (errmsg("Kerberos keytab resolving returned error %d",
 211                                                 retval)));
 212                 com_err("postgres", retval, "while resolving keytab file \"%s\"",
 213                                 pg_krb_server_keyfile);
 214                 krb5_free_context(pg_krb5_context);
 215                 return STATUS_ERROR;
 216         }
 217
 218         retval = krb5_sname_to_principal(pg_krb5_context, NULL, PG_KRB_SRVNAM,
 219                                                                          KRB5_NT_SRV_HST, &pg_krb5_server);
 220         if (retval)
 221         {
 222                 ereport(LOG,
 223                  (errmsg("Kerberos sname_to_principal(\"%s\") returned error %d",
 224                                  PG_KRB_SRVNAM, retval)));
 225                 com_err("postgres", retval,
 226                                 "while getting server principal for service \"%s\"",
 227                                 PG_KRB_SRVNAM);
 228                 krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
 229                 krb5_free_context(pg_krb5_context);
 230                 return STATUS_ERROR;
 231         }
 232
 233         pg_krb5_initialised = 1;
 234         return STATUS_OK;
 235 }
 236
 237
 238 /*
 239  * pg_krb5_recvauth -- server routine to receive authentication information
 240  *                                         from the client
 241  *
 242  * We still need to compare the username obtained from the client's setup
 243  * packet to the authenticated name, as described in pg_krb4_recvauth.  This
 244  * is a bit more problematic in v5, as described above in pg_an_to_ln.
 245  *
 246  * We have our own keytab file because postgres is unlikely to run as root,
 247  * and so cannot read the default keytab.
 248  */
 249 static int
 250 pg_krb5_recvauth(Port *port)
 251 {
 252         krb5_error_code retval;
 253         int                     ret;
 254         krb5_auth_context auth_context = NULL;
 255         krb5_ticket *ticket;
 256         char       *kusername;
 257
 258         ret = pg_krb5_init();
 259         if (ret != STATUS_OK)
 260                 return ret;
 261
 262         retval = krb5_recvauth(pg_krb5_context, &auth_context,
 263                                                    (krb5_pointer) & port->sock, PG_KRB_SRVNAM,
 264                                                    pg_krb5_server, 0, pg_krb5_keytab, &ticket);
 265         if (retval)
 266         {
 267                 ereport(LOG,
 268                                 (errmsg("Kerberos recvauth returned error %d",
 269                                                 retval)));
 270                 com_err("postgres", retval, "from krb5_recvauth");
 271                 return STATUS_ERROR;
 272         }
 273
 274         /*
 275          * The "client" structure comes out of the ticket and is therefore
 276          * authenticated.  Use it to check the username obtained from the
 277          * postmaster startup packet.
 278          *
 279          * I have no idea why this is considered necessary.
 280          */
 281 #if defined(HAVE_KRB5_TICKET_ENC_PART2)
 282         retval = krb5_unparse_name(pg_krb5_context,
 283                                                            ticket->enc_part2->client, &kusername);
 284 #elif defined(HAVE_KRB5_TICKET_CLIENT)
 285         retval = krb5_unparse_name(pg_krb5_context,
 286                                                            ticket->client, &kusername);
 287 #else
 288 #error "bogus configuration"
 289 #endif
 290         if (retval)
 291         {
 292                 ereport(LOG,
 293                                 (errmsg("Kerberos unparse_name returned error %d",
 294                                                 retval)));
 295                 com_err("postgres", retval, "while unparsing client name");
 296                 krb5_free_ticket(pg_krb5_context, ticket);
 297                 krb5_auth_con_free(pg_krb5_context, auth_context);
 298                 return STATUS_ERROR;
 299         }
 300
 301         kusername = pg_an_to_ln(kusername);
 302         if (strncmp(port->user_name, kusername, SM_DATABASE_USER))
 303         {
 304                 ereport(LOG,
 305                                 (errmsg("unexpected Kerberos user name received from client (received \"%s\", expected \"%s\")",
 306                                                 port->user_name, kusername)));
 307                 ret = STATUS_ERROR;
 308         }
 309         else
 310                 ret = STATUS_OK;
 311
 312         krb5_free_ticket(pg_krb5_context, ticket);
 313         krb5_auth_con_free(pg_krb5_context, auth_context);
 314         free(kusername);
 315
 316         return ret;
 317 }
 318
 319 #else
 320
 321 static int
 322 pg_krb5_recvauth(Port *port)
 323 {
 324         ereport(LOG,
 325                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 326                          errmsg("Kerberos 5 not implemented on this server")));
 327         return STATUS_ERROR;
 328 }
 329 #endif   /* KRB5 */
 330
 331
 332 /*
 333  * Tell the user the authentication failed, but not (much about) why.
 334  *
 335  * There is a tradeoff here between security concerns and making life
 336  * unnecessarily difficult for legitimate users.  We would not, for example,
 337  * want to report the password we were expecting to receive...
 338  * But it seems useful to report the username and authorization method
 339  * in use, and these are items that must be presumed known to an attacker
 340  * anyway.
 341  * Note that many sorts of failure report additional information in the
 342  * postmaster log, which we hope is only readable by good guys.
 343  */
 344 static void
 345 auth_failed(Port *port, int status)
 346 {
 347         const char *errstr;
 348
 349         /*
 350          * If we failed due to EOF from client, just quit; there's no point in
 351          * trying to send a message to the client, and not much point in
 352          * logging the failure in the postmaster log.  (Logging the failure
 353          * might be desirable, were it not for the fact that libpq closes the
 354          * connection unceremoniously if challenged for a password when it
 355          * hasn't got one to send.  We'll get a useless log entry for every
 356          * psql connection under password auth, even if it's perfectly
 357          * successful, if we log STATUS_EOF events.)
 358          */
 359         if (status == STATUS_EOF)
 360                 proc_exit(0);
 361
 362         switch (port->auth_method)
 363         {
 364                 case uaReject:
 365                         errstr = gettext_noop("authentication failed for user \"%s\": host rejected");
 366                         break;
 367                 case uaKrb4:
 368                         errstr = gettext_noop("Kerberos 4 authentication failed for user \"%s\"");
 369                         break;
 370                 case uaKrb5:
 371                         errstr = gettext_noop("Kerberos 5 authentication failed for user \"%s\"");
 372                         break;
 373                 case uaTrust:
 374                         errstr = gettext_noop("\"trust\" authentication failed for user \"%s\"");
 375                         break;
 376                 case uaIdent:
 377                         errstr = gettext_noop("Ident authentication failed for user \"%s\"");
 378                         break;
 379                 case uaMD5:
 380                 case uaCrypt:
 381                 case uaPassword:
 382                         errstr = gettext_noop("password authentication failed for user \"%s\"");
 383                         break;
 384 #ifdef USE_PAM
 385                 case uaPAM:
 386                         errstr = gettext_noop("PAM authentication failed for user \"%s\"");
 387                         break;
 388 #endif   /* USE_PAM */
 389                 default:
 390                         errstr = gettext_noop("authentication failed for user \"%s\": invalid authentication method");
 391                         break;
 392         }
 393
 394         ereport(FATAL,
 395                         (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 396                          errmsg(errstr, port->user_name)));
 397         /* doesn't return */
 398 }
 399
 400
 401 /*
 402  * Client authentication starts here.  If there is an error, this
 403  * function does not return and the backend process is terminated.
 404  */
 405 void
 406 ClientAuthentication(Port *port)
 407 {
 408         int                     status = STATUS_ERROR;
 409
 410         /*
 411          * Get the authentication method to use for this frontend/database
 412          * combination.  Note: a failure return indicates a problem with the
 413          * hba config file, not with the request.  hba.c should have dropped
 414          * an error message into the postmaster logfile if it failed.
 415          */
 416         if (hba_getauthmethod(port) != STATUS_OK)
 417                 ereport(FATAL,
 418                                 (errcode(ERRCODE_CONFIG_FILE_ERROR),
 419                                  errmsg("missing or erroneous pg_hba.conf file"),
 420                                  errhint("See server log for details.")));
 421
 422         switch (port->auth_method)
 423         {
 424                 case uaReject:
 425
 426                         /*
 427                          * This could have come from an explicit "reject" entry in
 428                          * pg_hba.conf, but more likely it means there was no matching
 429                          * entry.  Take pity on the poor user and issue a helpful
 430                          * error message.  NOTE: this is not a security breach,
 431                          * because all the info reported here is known at the frontend
 432                          * and must be assumed known to bad guys. We're merely helping
 433                          * out the less clueful good guys.
 434                          */
 435                         {
 436                                 char            hostinfo[NI_MAXHOST];
 437
 438                                 getnameinfo_all(&port->raddr.addr, port->raddr.salen,
 439                                                                 hostinfo, sizeof(hostinfo),
 440                                                                 NULL, 0,
 441                                                                 NI_NUMERICHOST);
 442
 443 #ifdef USE_SSL
 444                                 ereport(FATAL,
 445                                    (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 446                                         errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\", %s",
 447                                                    hostinfo, port->user_name, port->database_name,
 448                                    port->ssl ? gettext("SSL on") : gettext("SSL off"))));
 449 #else
 450                                 ereport(FATAL,
 451                                    (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 452                                         errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\"",
 453                                            hostinfo, port->user_name, port->database_name)));
 454 #endif
 455                                 break;
 456                         }
 457
 458                 case uaKrb4:
 459                         /* Kerberos 4 only seems to work with AF_INET. */
 460                         if (port->raddr.addr.ss_family != AF_INET
 461                                 || port->laddr.addr.ss_family != AF_INET)
 462                                 ereport(FATAL,
 463                                                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 464                                    errmsg("Kerberos 4 only supports IPv4 connections")));
 465                         sendAuthRequest(port, AUTH_REQ_KRB4);
 466                         status = pg_krb4_recvauth(port);
 467                         break;
 468
 469                 case uaKrb5:
 470                         sendAuthRequest(port, AUTH_REQ_KRB5);
 471                         status = pg_krb5_recvauth(port);
 472                         break;
 473
 474                 case uaIdent:
 475
 476                         /*
 477                          * If we are doing ident on unix-domain sockets, use SCM_CREDS
 478                          * only if it is defined and SO_PEERCRED isn't.
 479                          */
 480 #if !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED) && \
 481         (defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || \
 482          (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS)))
 483                         if (port->raddr.addr.ss_family == AF_UNIX)
 484                         {
 485 #if defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
 486
 487                                 /*
 488                                  * Receive credentials on next message receipt, BSD/OS,
 489                                  * NetBSD. We need to set this before the client sends the
 490                                  * next packet.
 491                                  */
 492                                 int                     on = 1;
 493
 494                                 if (setsockopt(port->sock, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
 495                                         ereport(FATAL,
 496                                                         (errcode_for_socket_access(),
 497                                         errmsg("could not enable credential reception: %m")));
 498 #endif
 499
 500                                 sendAuthRequest(port, AUTH_REQ_SCM_CREDS);
 501                         }
 502 #endif
 503                         status = authident(port);
 504                         break;
 505
 506                 case uaMD5:
 507                         sendAuthRequest(port, AUTH_REQ_MD5);
 508                         status = recv_and_check_password_packet(port);
 509                         break;
 510
 511                 case uaCrypt:
 512                         sendAuthRequest(port, AUTH_REQ_CRYPT);
 513                         status = recv_and_check_password_packet(port);
 514                         break;
 515
 516                 case uaPassword:
 517                         sendAuthRequest(port, AUTH_REQ_PASSWORD);
 518                         status = recv_and_check_password_packet(port);
 519                         break;
 520
 521 #ifdef USE_PAM
 522                 case uaPAM:
 523                         pam_port_cludge = port;
 524                         status = CheckPAMAuth(port, port->user_name, "");
 525                         break;
 526 #endif   /* USE_PAM */
 527
 528                 case uaTrust:
 529                         status = STATUS_OK;
 530                         break;
 531         }
 532
 533         if (status == STATUS_OK)
 534                 sendAuthRequest(port, AUTH_REQ_OK);
 535         else
 536                 auth_failed(port, status);
 537 }
 538
 539
 540 /*
 541  * Send an authentication request packet to the frontend.
 542  */
 543 static void
 544 sendAuthRequest(Port *port, AuthRequest areq)
 545 {
 546         StringInfoData buf;
 547
 548         pq_beginmessage(&buf, 'R');
 549         pq_sendint(&buf, (int32) areq, sizeof(int32));
 550
 551         /* Add the salt for encrypted passwords. */
 552         if (areq == AUTH_REQ_MD5)
 553                 pq_sendbytes(&buf, port->md5Salt, 4);
 554         else if (areq == AUTH_REQ_CRYPT)
 555                 pq_sendbytes(&buf, port->cryptSalt, 2);
 556
 557         pq_endmessage(&buf);
 558
 559         /*
 560          * Flush message so client will see it, except for AUTH_REQ_OK, which
 561          * need not be sent until we are ready for queries.
 562          */
 563         if (areq != AUTH_REQ_OK)
 564                 pq_flush();
 565 }
 566
 567
 568 #ifdef USE_PAM
 569
 570 /*
 571  * PAM conversation function
 572  */
 573
 574 static int
 575 pam_passwd_conv_proc(int num_msg, const struct pam_message ** msg,
 576                                          struct pam_response ** resp, void *appdata_ptr)
 577 {
 578         if (num_msg != 1 || msg[0]->msg_style != PAM_PROMPT_ECHO_OFF)
 579         {
 580                 switch (msg[0]->msg_style)
 581                 {
 582                         case PAM_ERROR_MSG:
 583                                 ereport(LOG,
 584                                                 (errmsg("error from underlying PAM layer: %s",
 585                                                                 msg[0]->msg)));
 586                                 return PAM_CONV_ERR;
 587                         default:
 588                                 ereport(LOG,
 589                                                 (errmsg("unsupported PAM conversation %d/%s",
 590                                                                 msg[0]->msg_style, msg[0]->msg)));
 591                                 return PAM_CONV_ERR;
 592                 }
 593         }
 594
 595         if (!appdata_ptr)
 596         {
 597                 /*
 598                  * Workaround for Solaris 2.6 where the PAM library is broken and
 599                  * does not pass appdata_ptr to the conversation routine
 600                  */
 601                 appdata_ptr = pam_passwd;
 602         }
 603
 604         /*
 605          * Password wasn't passed to PAM the first time around - let's go ask
 606          * the client to send a password, which we then stuff into PAM.
 607          */
 608         if (strlen(appdata_ptr) == 0)
 609         {
 610                 char       *passwd;
 611
 612                 sendAuthRequest(pam_port_cludge, AUTH_REQ_PASSWORD);
 613                 passwd = recv_password_packet(pam_port_cludge);
 614
 615                 if (passwd == NULL)
 616                         return PAM_CONV_ERR;    /* client didn't want to send password */
 617
 618                 if (strlen(passwd) == 0)
 619                 {
 620                         ereport(LOG,
 621                                         (errmsg("empty password returned by client")));
 622                         return PAM_CONV_ERR;
 623                 }
 624                 appdata_ptr = passwd;
 625         }
 626
 627         /*
 628          * Explicitly not using palloc here - PAM will free this memory in
 629          * pam_end()
 630          */
 631         *resp = calloc(num_msg, sizeof(struct pam_response));
 632         if (!*resp)
 633         {
 634                 ereport(LOG,
 635                                 (errcode(ERRCODE_OUT_OF_MEMORY),
 636                                  errmsg("out of memory")));
 637                 return PAM_CONV_ERR;
 638         }
 639
 640         (*resp)[0].resp = strdup((char *) appdata_ptr);
 641         (*resp)[0].resp_retcode = 0;
 642
 643         return ((*resp)[0].resp ? PAM_SUCCESS : PAM_CONV_ERR);
 644 }
 645
 646
 647 /*
 648  * Check authentication against PAM.
 649  */
 650 static int
 651 CheckPAMAuth(Port *port, char *user, char *password)
 652 {
 653         int                     retval;
 654         pam_handle_t *pamh = NULL;
 655
 656         /*
 657          * Apparently, Solaris 2.6 is broken, and needs ugly static variable
 658          * workaround
 659          */
 660         pam_passwd = password;
 661
 662         /*
 663          * Set the application data portion of the conversation struct This is
 664          * later used inside the PAM conversation to pass the password to the
 665          * authentication module.
 666          */
 667         pam_passw_conv.appdata_ptr = (char *) password;         /* from password above,
 668                                                                                                                  * not allocated */
 669
 670         /* Optionally, one can set the service name in pg_hba.conf */
 671         if (port->auth_arg && port->auth_arg[0] != '\0')
 672                 retval = pam_start(port->auth_arg, "pgsql@",
 673                                                    &pam_passw_conv, &pamh);
 674         else
 675                 retval = pam_start(PGSQL_PAM_SERVICE, "pgsql@",
 676                                                    &pam_passw_conv, &pamh);
 677
 678         if (retval != PAM_SUCCESS)
 679         {
 680                 ereport(LOG,
 681                                 (errmsg("could not create PAM authenticator: %s",
 682                                                 pam_strerror(pamh, retval))));
 683                 pam_passwd = NULL;              /* Unset pam_passwd */
 684                 return STATUS_ERROR;
 685         }
 686
 687         retval = pam_set_item(pamh, PAM_USER, user);
 688
 689         if (retval != PAM_SUCCESS)
 690         {
 691                 ereport(LOG,
 692                                 (errmsg("pam_set_item(PAM_USER) failed: %s",
 693                                                 pam_strerror(pamh, retval))));
 694                 pam_passwd = NULL;              /* Unset pam_passwd */
 695                 return STATUS_ERROR;
 696         }
 697
 698         retval = pam_set_item(pamh, PAM_CONV, &pam_passw_conv);
 699
 700         if (retval != PAM_SUCCESS)
 701         {
 702                 ereport(LOG,
 703                                 (errmsg("pam_set_item(PAM_CONV) failed: %s",
 704                                                 pam_strerror(pamh, retval))));
 705                 pam_passwd = NULL;              /* Unset pam_passwd */
 706                 return STATUS_ERROR;
 707         }
 708
 709         retval = pam_authenticate(pamh, 0);
 710
 711         if (retval != PAM_SUCCESS)
 712         {
 713                 ereport(LOG,
 714                                 (errmsg("pam_authenticate failed: %s",
 715                                                 pam_strerror(pamh, retval))));
 716                 pam_passwd = NULL;              /* Unset pam_passwd */
 717                 return STATUS_ERROR;
 718         }
 719
 720         retval = pam_acct_mgmt(pamh, 0);
 721
 722         if (retval != PAM_SUCCESS)
 723         {
 724                 ereport(LOG,
 725                                 (errmsg("pam_acct_mgmt failed: %s",
 726                                                 pam_strerror(pamh, retval))));
 727                 pam_passwd = NULL;              /* Unset pam_passwd */
 728                 return STATUS_ERROR;
 729         }
 730
 731         retval = pam_end(pamh, retval);
 732
 733         if (retval != PAM_SUCCESS)
 734         {
 735                 ereport(LOG,
 736                                 (errmsg("could not release PAM authenticator: %s",
 737                                                 pam_strerror(pamh, retval))));
 738         }
 739
 740         pam_passwd = NULL;                      /* Unset pam_passwd */
 741
 742         return (retval == PAM_SUCCESS ? STATUS_OK : STATUS_ERROR);
 743 }
 744 #endif   /* USE_PAM */
 745
 746
 747 /*
 748  * Collect password response packet from frontend.
 749  *
 750  * Returns NULL if couldn't get password, else palloc'd string.
 751  */
 752 static char *
 753 recv_password_packet(Port *port)
 754 {
 755         StringInfoData buf;
 756
 757         if (PG_PROTOCOL_MAJOR(port->proto) >= 3)
 758         {
 759                 /* Expect 'p' message type */
 760                 int                     mtype;
 761
 762                 mtype = pq_getbyte();
 763                 if (mtype != 'p')
 764                 {
 765                         /*
 766                          * If the client just disconnects without offering a password,
 767                          * don't make a log entry.  This is legal per protocol spec
 768                          * and in fact commonly done by psql, so complaining just
 769                          * clutters the log.
 770                          */
 771                         if (mtype != EOF)
 772                                 ereport(COMMERROR,
 773                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 774                                 errmsg("expected password response, got message type %d",
 775                                            mtype)));
 776                         return NULL;            /* EOF or bad message type */
 777                 }
 778         }
 779         else
 780         {
 781                 /* For pre-3.0 clients, avoid log entry if they just disconnect */
 782                 if (pq_peekbyte() == EOF)
 783                         return NULL;            /* EOF */
 784         }
 785
 786         initStringInfo(&buf);
 787         if (pq_getmessage(&buf, 1000))          /* receive password */
 788         {
 789                 /* EOF - pq_getmessage already logged a suitable message */
 790                 pfree(buf.data);
 791                 return NULL;
 792         }
 793
 794         /*
 795          * Apply sanity check: password packet length should agree with length
 796          * of contained string.  Note it is safe to use strlen here because
 797          * StringInfo is guaranteed to have an appended '\0'.
 798          */
 799         if (strlen(buf.data) + 1 != buf.len)
 800                 ereport(COMMERROR,
 801                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 802                                  errmsg("invalid password packet size")));
 803
 804         /* Do not echo password to logs, for security. */
 805         ereport(DEBUG5,
 806                         (errmsg("received password packet")));
 807
 808         /*
 809          * Return the received string.  Note we do not attempt to do any
 810          * character-set conversion on it; since we don't yet know the
 811          * client's encoding, there wouldn't be much point.
 812          */
 813         return buf.data;
 814 }
 815
 816
 817 /*
 818  * Called when we have sent an authorization request for a password.
 819  * Get the response and check it.
 820  */
 821 static int
 822 recv_and_check_password_packet(Port *port)
 823 {
 824         char       *passwd;
 825         int                     result;
 826
 827         passwd = recv_password_packet(port);
 828
 829         if (passwd == NULL)
 830                 return STATUS_EOF;              /* client wouldn't send password */
 831
 832         result = md5_crypt_verify(port, port->user_name, passwd);
 833
 834         pfree(passwd);
 835
 836         return result;
 837 }