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) 1996-2005, 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 1.123 2005/02/22 04:35:57 momjian 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 /* Some old versions of Kerberos do not include <com_err.h> in <krb5.h> */
 154 #if !defined(__COM_ERR_H) && !defined(__COM_ERR_H__)
 155 #include <com_err.h>
 156 #endif
 157
 158 /*
 159  * pg_an_to_ln -- return the local name corresponding to an authentication
 160  *                                name
 161  *
 162  * XXX Assumes that the first aname component is the user name.  This is NOT
 163  *         necessarily so, since an aname can actually be something out of your
 164  *         worst X.400 nightmare, like
 165  *                ORGANIZATION=U. C. Berkeley/NAME=Paul M. Aoki@CS.BERKELEY.EDU
 166  *         Note that the MIT an_to_ln code does the same thing if you don't
 167  *         provide an aname mapping database...it may be a better idea to use
 168  *         krb5_an_to_ln, except that it punts if multiple components are found,
 169  *         and we can't afford to punt.
 170  */
 171 static char *
 172 pg_an_to_ln(char *aname)
 173 {
 174         char       *p;
 175
 176         if ((p = strchr(aname, '/')) || (p = strchr(aname, '@')))
 177                 *p = '\0';
 178         return aname;
 179 }
 180
 181
 182 /*
 183  * Various krb5 state which is not connection specfic, and a flag to
 184  * indicate whether we have initialised it yet.
 185  */
 186 static int      pg_krb5_initialised;
 187 static krb5_context pg_krb5_context;
 188 static krb5_keytab pg_krb5_keytab;
 189 static krb5_principal pg_krb5_server;
 190
 191
 192 static int
 193 pg_krb5_init(void)
 194 {
 195         krb5_error_code retval;
 196
 197         if (pg_krb5_initialised)
 198                 return STATUS_OK;
 199
 200         retval = krb5_init_context(&pg_krb5_context);
 201         if (retval)
 202         {
 203                 ereport(LOG,
 204                                 (errmsg("Kerberos initialization returned error %d",
 205                                                 retval)));
 206                 com_err("postgres", retval, "while initializing krb5");
 207                 return STATUS_ERROR;
 208         }
 209
 210         retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab);
 211         if (retval)
 212         {
 213                 ereport(LOG,
 214                                 (errmsg("Kerberos keytab resolving returned error %d",
 215                                                 retval)));
 216                 com_err("postgres", retval, "while resolving keytab file \"%s\"",
 217                                 pg_krb_server_keyfile);
 218                 krb5_free_context(pg_krb5_context);
 219                 return STATUS_ERROR;
 220         }
 221
 222         retval = krb5_sname_to_principal(pg_krb5_context, NULL, PG_KRB_SRVNAM,
 223                                                                          KRB5_NT_SRV_HST, &pg_krb5_server);
 224         if (retval)
 225         {
 226                 ereport(LOG,
 227                  (errmsg("Kerberos sname_to_principal(\"%s\") returned error %d",
 228                                  PG_KRB_SRVNAM, retval)));
 229                 com_err("postgres", retval,
 230                                 "while getting server principal for service \"%s\"",
 231                                 PG_KRB_SRVNAM);
 232                 krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
 233                 krb5_free_context(pg_krb5_context);
 234                 return STATUS_ERROR;
 235         }
 236
 237         pg_krb5_initialised = 1;
 238         return STATUS_OK;
 239 }
 240
 241
 242 /*
 243  * pg_krb5_recvauth -- server routine to receive authentication information
 244  *                                         from the client
 245  *
 246  * We still need to compare the username obtained from the client's setup
 247  * packet to the authenticated name, as described in pg_krb4_recvauth.  This
 248  * is a bit more problematic in v5, as described above in pg_an_to_ln.
 249  *
 250  * We have our own keytab file because postgres is unlikely to run as root,
 251  * and so cannot read the default keytab.
 252  */
 253 static int
 254 pg_krb5_recvauth(Port *port)
 255 {
 256         krb5_error_code retval;
 257         int                     ret;
 258         krb5_auth_context auth_context = NULL;
 259         krb5_ticket *ticket;
 260         char       *kusername;
 261
 262         ret = pg_krb5_init();
 263         if (ret != STATUS_OK)
 264                 return ret;
 265
 266         retval = krb5_recvauth(pg_krb5_context, &auth_context,
 267                                                    (krb5_pointer) & port->sock, PG_KRB_SRVNAM,
 268                                                    pg_krb5_server, 0, pg_krb5_keytab, &ticket);
 269         if (retval)
 270         {
 271                 ereport(LOG,
 272                                 (errmsg("Kerberos recvauth returned error %d",
 273                                                 retval)));
 274                 com_err("postgres", retval, "from krb5_recvauth");
 275                 return STATUS_ERROR;
 276         }
 277
 278         /*
 279          * The "client" structure comes out of the ticket and is therefore
 280          * authenticated.  Use it to check the username obtained from the
 281          * postmaster startup packet.
 282          *
 283          * I have no idea why this is considered necessary.
 284          */
 285 #if defined(HAVE_KRB5_TICKET_ENC_PART2)
 286         retval = krb5_unparse_name(pg_krb5_context,
 287                                                            ticket->enc_part2->client, &kusername);
 288 #elif defined(HAVE_KRB5_TICKET_CLIENT)
 289         retval = krb5_unparse_name(pg_krb5_context,
 290                                                            ticket->client, &kusername);
 291 #else
 292 #error "bogus configuration"
 293 #endif
 294         if (retval)
 295         {
 296                 ereport(LOG,
 297                                 (errmsg("Kerberos unparse_name returned error %d",
 298                                                 retval)));
 299                 com_err("postgres", retval, "while unparsing client name");
 300                 krb5_free_ticket(pg_krb5_context, ticket);
 301                 krb5_auth_con_free(pg_krb5_context, auth_context);
 302                 return STATUS_ERROR;
 303         }
 304
 305         kusername = pg_an_to_ln(kusername);
 306         if (strncmp(port->user_name, kusername, SM_DATABASE_USER))
 307         {
 308                 ereport(LOG,
 309                                 (errmsg("unexpected Kerberos user name received from client (received \"%s\", expected \"%s\")",
 310                                                 port->user_name, kusername)));
 311                 ret = STATUS_ERROR;
 312         }
 313         else
 314                 ret = STATUS_OK;
 315
 316         krb5_free_ticket(pg_krb5_context, ticket);
 317         krb5_auth_con_free(pg_krb5_context, auth_context);
 318         free(kusername);
 319
 320         return ret;
 321 }
 322
 323 #else
 324
 325 static int
 326 pg_krb5_recvauth(Port *port)
 327 {
 328         ereport(LOG,
 329                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 330                          errmsg("Kerberos 5 not implemented on this server")));
 331         return STATUS_ERROR;
 332 }
 333 #endif   /* KRB5 */
 334
 335
 336 /*
 337  * Tell the user the authentication failed, but not (much about) why.
 338  *
 339  * There is a tradeoff here between security concerns and making life
 340  * unnecessarily difficult for legitimate users.  We would not, for example,
 341  * want to report the password we were expecting to receive...
 342  * But it seems useful to report the username and authorization method
 343  * in use, and these are items that must be presumed known to an attacker
 344  * anyway.
 345  * Note that many sorts of failure report additional information in the
 346  * postmaster log, which we hope is only readable by good guys.
 347  */
 348 static void
 349 auth_failed(Port *port, int status)
 350 {
 351         const char *errstr;
 352
 353         /*
 354          * If we failed due to EOF from client, just quit; there's no point in
 355          * trying to send a message to the client, and not much point in
 356          * logging the failure in the postmaster log.  (Logging the failure
 357          * might be desirable, were it not for the fact that libpq closes the
 358          * connection unceremoniously if challenged for a password when it
 359          * hasn't got one to send.  We'll get a useless log entry for every
 360          * psql connection under password auth, even if it's perfectly
 361          * successful, if we log STATUS_EOF events.)
 362          */
 363         if (status == STATUS_EOF)
 364                 proc_exit(0);
 365
 366         switch (port->auth_method)
 367         {
 368                 case uaReject:
 369                         errstr = gettext_noop("authentication failed for user \"%s\": host rejected");
 370                         break;
 371                 case uaKrb4:
 372                         errstr = gettext_noop("Kerberos 4 authentication failed for user \"%s\"");
 373                         break;
 374                 case uaKrb5:
 375                         errstr = gettext_noop("Kerberos 5 authentication failed for user \"%s\"");
 376                         break;
 377                 case uaTrust:
 378                         errstr = gettext_noop("\"trust\" authentication failed for user \"%s\"");
 379                         break;
 380                 case uaIdent:
 381                         errstr = gettext_noop("Ident authentication failed for user \"%s\"");
 382                         break;
 383                 case uaMD5:
 384                 case uaCrypt:
 385                 case uaPassword:
 386                         errstr = gettext_noop("password authentication failed for user \"%s\"");
 387                         break;
 388 #ifdef USE_PAM
 389                 case uaPAM:
 390                         errstr = gettext_noop("PAM authentication failed for user \"%s\"");
 391                         break;
 392 #endif   /* USE_PAM */
 393                 default:
 394                         errstr = gettext_noop("authentication failed for user \"%s\": invalid authentication method");
 395                         break;
 396         }
 397
 398         ereport(FATAL,
 399                         (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 400                          errmsg(errstr, port->user_name)));
 401         /* doesn't return */
 402 }
 403
 404
 405 /*
 406  * Client authentication starts here.  If there is an error, this
 407  * function does not return and the backend process is terminated.
 408  */
 409 void
 410 ClientAuthentication(Port *port)
 411 {
 412         int                     status = STATUS_ERROR;
 413
 414         /*
 415          * Get the authentication method to use for this frontend/database
 416          * combination.  Note: a failure return indicates a problem with the
 417          * hba config file, not with the request.  hba.c should have dropped
 418          * an error message into the postmaster logfile if it failed.
 419          */
 420         if (hba_getauthmethod(port) != STATUS_OK)
 421                 ereport(FATAL,
 422                                 (errcode(ERRCODE_CONFIG_FILE_ERROR),
 423                                  errmsg("missing or erroneous pg_hba.conf file"),
 424                                  errhint("See server log for details.")));
 425
 426         switch (port->auth_method)
 427         {
 428                 case uaReject:
 429
 430                         /*
 431                          * This could have come from an explicit "reject" entry in
 432                          * pg_hba.conf, but more likely it means there was no matching
 433                          * entry.  Take pity on the poor user and issue a helpful
 434                          * error message.  NOTE: this is not a security breach,
 435                          * because all the info reported here is known at the frontend
 436                          * and must be assumed known to bad guys. We're merely helping
 437                          * out the less clueful good guys.
 438                          */
 439                         {
 440                                 char            hostinfo[NI_MAXHOST];
 441
 442                                 getnameinfo_all(&port->raddr.addr, port->raddr.salen,
 443                                                                 hostinfo, sizeof(hostinfo),
 444                                                                 NULL, 0,
 445                                                                 NI_NUMERICHOST);
 446
 447 #ifdef USE_SSL
 448                                 ereport(FATAL,
 449                                    (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 450                                         errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\", %s",
 451                                                    hostinfo, port->user_name, port->database_name,
 452                                    port->ssl ? _("SSL on") : _("SSL off"))));
 453 #else
 454                                 ereport(FATAL,
 455                                    (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 456                                         errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\"",
 457                                            hostinfo, port->user_name, port->database_name)));
 458 #endif
 459                                 break;
 460                         }
 461
 462                 case uaKrb4:
 463                         /* Kerberos 4 only seems to work with AF_INET. */
 464                         if (port->raddr.addr.ss_family != AF_INET
 465                                 || port->laddr.addr.ss_family != AF_INET)
 466                                 ereport(FATAL,
 467                                                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 468                                    errmsg("Kerberos 4 only supports IPv4 connections")));
 469                         sendAuthRequest(port, AUTH_REQ_KRB4);
 470                         status = pg_krb4_recvauth(port);
 471                         break;
 472
 473                 case uaKrb5:
 474                         sendAuthRequest(port, AUTH_REQ_KRB5);
 475                         status = pg_krb5_recvauth(port);
 476                         break;
 477
 478                 case uaIdent:
 479
 480                         /*
 481                          * If we are doing ident on unix-domain sockets, use SCM_CREDS
 482                          * only if it is defined and SO_PEERCRED isn't.
 483                          */
 484 #if !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED) && \
 485         (defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || \
 486          (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS)))
 487                         if (port->raddr.addr.ss_family == AF_UNIX)
 488                         {
 489 #if defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
 490
 491                                 /*
 492                                  * Receive credentials on next message receipt, BSD/OS,
 493                                  * NetBSD. We need to set this before the client sends the
 494                                  * next packet.
 495                                  */
 496                                 int                     on = 1;
 497
 498                                 if (setsockopt(port->sock, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
 499                                         ereport(FATAL,
 500                                                         (errcode_for_socket_access(),
 501                                         errmsg("could not enable credential reception: %m")));
 502 #endif
 503
 504                                 sendAuthRequest(port, AUTH_REQ_SCM_CREDS);
 505                         }
 506 #endif
 507                         status = authident(port);
 508                         break;
 509
 510                 case uaMD5:
 511                         sendAuthRequest(port, AUTH_REQ_MD5);
 512                         status = recv_and_check_password_packet(port);
 513                         break;
 514
 515                 case uaCrypt:
 516                         sendAuthRequest(port, AUTH_REQ_CRYPT);
 517                         status = recv_and_check_password_packet(port);
 518                         break;
 519
 520                 case uaPassword:
 521                         sendAuthRequest(port, AUTH_REQ_PASSWORD);
 522                         status = recv_and_check_password_packet(port);
 523                         break;
 524
 525 #ifdef USE_PAM
 526                 case uaPAM:
 527                         pam_port_cludge = port;
 528                         status = CheckPAMAuth(port, port->user_name, "");
 529                         break;
 530 #endif   /* USE_PAM */
 531
 532                 case uaTrust:
 533                         status = STATUS_OK;
 534                         break;
 535         }
 536
 537         if (status == STATUS_OK)
 538                 sendAuthRequest(port, AUTH_REQ_OK);
 539         else
 540                 auth_failed(port, status);
 541 }
 542
 543
 544 /*
 545  * Send an authentication request packet to the frontend.
 546  */
 547 static void
 548 sendAuthRequest(Port *port, AuthRequest areq)
 549 {
 550         StringInfoData buf;
 551
 552         pq_beginmessage(&buf, 'R');
 553         pq_sendint(&buf, (int32) areq, sizeof(int32));
 554
 555         /* Add the salt for encrypted passwords. */
 556         if (areq == AUTH_REQ_MD5)
 557                 pq_sendbytes(&buf, port->md5Salt, 4);
 558         else if (areq == AUTH_REQ_CRYPT)
 559                 pq_sendbytes(&buf, port->cryptSalt, 2);
 560
 561         pq_endmessage(&buf);
 562
 563         /*
 564          * Flush message so client will see it, except for AUTH_REQ_OK, which
 565          * need not be sent until we are ready for queries.
 566          */
 567         if (areq != AUTH_REQ_OK)
 568                 pq_flush();
 569 }
 570
 571
 572 #ifdef USE_PAM
 573
 574 /*
 575  * PAM conversation function
 576  */
 577
 578 static int
 579 pam_passwd_conv_proc(int num_msg, const struct pam_message ** msg,
 580                                          struct pam_response ** resp, void *appdata_ptr)
 581 {
 582         if (num_msg != 1 || msg[0]->msg_style != PAM_PROMPT_ECHO_OFF)
 583         {
 584                 switch (msg[0]->msg_style)
 585                 {
 586                         case PAM_ERROR_MSG:
 587                                 ereport(LOG,
 588                                                 (errmsg("error from underlying PAM layer: %s",
 589                                                                 msg[0]->msg)));
 590                                 return PAM_CONV_ERR;
 591                         default:
 592                                 ereport(LOG,
 593                                                 (errmsg("unsupported PAM conversation %d/%s",
 594                                                                 msg[0]->msg_style, msg[0]->msg)));
 595                                 return PAM_CONV_ERR;
 596                 }
 597         }
 598
 599         if (!appdata_ptr)
 600         {
 601                 /*
 602                  * Workaround for Solaris 2.6 where the PAM library is broken and
 603                  * does not pass appdata_ptr to the conversation routine
 604                  */
 605                 appdata_ptr = pam_passwd;
 606         }
 607
 608         /*
 609          * Password wasn't passed to PAM the first time around - let's go ask
 610          * the client to send a password, which we then stuff into PAM.
 611          */
 612         if (strlen(appdata_ptr) == 0)
 613         {
 614                 char       *passwd;
 615
 616                 sendAuthRequest(pam_port_cludge, AUTH_REQ_PASSWORD);
 617                 passwd = recv_password_packet(pam_port_cludge);
 618
 619                 if (passwd == NULL)
 620                         return PAM_CONV_ERR;    /* client didn't want to send password */
 621
 622                 if (strlen(passwd) == 0)
 623                 {
 624                         ereport(LOG,
 625                                         (errmsg("empty password returned by client")));
 626                         return PAM_CONV_ERR;
 627                 }
 628                 appdata_ptr = passwd;
 629         }
 630
 631         /*
 632          * Explicitly not using palloc here - PAM will free this memory in
 633          * pam_end()
 634          */
 635         *resp = calloc(num_msg, sizeof(struct pam_response));
 636         if (!*resp)
 637         {
 638                 ereport(LOG,
 639                                 (errcode(ERRCODE_OUT_OF_MEMORY),
 640                                  errmsg("out of memory")));
 641                 return PAM_CONV_ERR;
 642         }
 643
 644         (*resp)[0].resp = strdup((char *) appdata_ptr);
 645         (*resp)[0].resp_retcode = 0;
 646
 647         return ((*resp)[0].resp ? PAM_SUCCESS : PAM_CONV_ERR);
 648 }
 649
 650
 651 /*
 652  * Check authentication against PAM.
 653  */
 654 static int
 655 CheckPAMAuth(Port *port, char *user, char *password)
 656 {
 657         int                     retval;
 658         pam_handle_t *pamh = NULL;
 659
 660         /*
 661          * Apparently, Solaris 2.6 is broken, and needs ugly static variable
 662          * workaround
 663          */
 664         pam_passwd = password;
 665
 666         /*
 667          * Set the application data portion of the conversation struct This is
 668          * later used inside the PAM conversation to pass the password to the
 669          * authentication module.
 670          */
 671         pam_passw_conv.appdata_ptr = (char *) password;         /* from password above,
 672                                                                                                                  * not allocated */
 673
 674         /* Optionally, one can set the service name in pg_hba.conf */
 675         if (port->auth_arg && port->auth_arg[0] != '\0')
 676                 retval = pam_start(port->auth_arg, "pgsql@",
 677                                                    &pam_passw_conv, &pamh);
 678         else
 679                 retval = pam_start(PGSQL_PAM_SERVICE, "pgsql@",
 680                                                    &pam_passw_conv, &pamh);
 681
 682         if (retval != PAM_SUCCESS)
 683         {
 684                 ereport(LOG,
 685                                 (errmsg("could not create PAM authenticator: %s",
 686                                                 pam_strerror(pamh, retval))));
 687                 pam_passwd = NULL;              /* Unset pam_passwd */
 688                 return STATUS_ERROR;
 689         }
 690
 691         retval = pam_set_item(pamh, PAM_USER, user);
 692
 693         if (retval != PAM_SUCCESS)
 694         {
 695                 ereport(LOG,
 696                                 (errmsg("pam_set_item(PAM_USER) failed: %s",
 697                                                 pam_strerror(pamh, retval))));
 698                 pam_passwd = NULL;              /* Unset pam_passwd */
 699                 return STATUS_ERROR;
 700         }
 701
 702         retval = pam_set_item(pamh, PAM_CONV, &pam_passw_conv);
 703
 704         if (retval != PAM_SUCCESS)
 705         {
 706                 ereport(LOG,
 707                                 (errmsg("pam_set_item(PAM_CONV) failed: %s",
 708                                                 pam_strerror(pamh, retval))));
 709                 pam_passwd = NULL;              /* Unset pam_passwd */
 710                 return STATUS_ERROR;
 711         }
 712
 713         retval = pam_authenticate(pamh, 0);
 714
 715         if (retval != PAM_SUCCESS)
 716         {
 717                 ereport(LOG,
 718                                 (errmsg("pam_authenticate failed: %s",
 719                                                 pam_strerror(pamh, retval))));
 720                 pam_passwd = NULL;              /* Unset pam_passwd */
 721                 return STATUS_ERROR;
 722         }
 723
 724         retval = pam_acct_mgmt(pamh, 0);
 725
 726         if (retval != PAM_SUCCESS)
 727         {
 728                 ereport(LOG,
 729                                 (errmsg("pam_acct_mgmt failed: %s",
 730                                                 pam_strerror(pamh, retval))));
 731                 pam_passwd = NULL;              /* Unset pam_passwd */
 732                 return STATUS_ERROR;
 733         }
 734
 735         retval = pam_end(pamh, retval);
 736
 737         if (retval != PAM_SUCCESS)
 738         {
 739                 ereport(LOG,
 740                                 (errmsg("could not release PAM authenticator: %s",
 741                                                 pam_strerror(pamh, retval))));
 742         }
 743
 744         pam_passwd = NULL;                      /* Unset pam_passwd */
 745
 746         return (retval == PAM_SUCCESS ? STATUS_OK : STATUS_ERROR);
 747 }
 748 #endif   /* USE_PAM */
 749
 750
 751 /*
 752  * Collect password response packet from frontend.
 753  *
 754  * Returns NULL if couldn't get password, else palloc'd string.
 755  */
 756 static char *
 757 recv_password_packet(Port *port)
 758 {
 759         StringInfoData buf;
 760
 761         if (PG_PROTOCOL_MAJOR(port->proto) >= 3)
 762         {
 763                 /* Expect 'p' message type */
 764                 int                     mtype;
 765
 766                 mtype = pq_getbyte();
 767                 if (mtype != 'p')
 768                 {
 769                         /*
 770                          * If the client just disconnects without offering a password,
 771                          * don't make a log entry.  This is legal per protocol spec
 772                          * and in fact commonly done by psql, so complaining just
 773                          * clutters the log.
 774                          */
 775                         if (mtype != EOF)
 776                                 ereport(COMMERROR,
 777                                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 778                                 errmsg("expected password response, got message type %d",
 779                                            mtype)));
 780                         return NULL;            /* EOF or bad message type */
 781                 }
 782         }
 783         else
 784         {
 785                 /* For pre-3.0 clients, avoid log entry if they just disconnect */
 786                 if (pq_peekbyte() == EOF)
 787                         return NULL;            /* EOF */
 788         }
 789
 790         initStringInfo(&buf);
 791         if (pq_getmessage(&buf, 1000))          /* receive password */
 792         {
 793                 /* EOF - pq_getmessage already logged a suitable message */
 794                 pfree(buf.data);
 795                 return NULL;
 796         }
 797
 798         /*
 799          * Apply sanity check: password packet length should agree with length
 800          * of contained string.  Note it is safe to use strlen here because
 801          * StringInfo is guaranteed to have an appended '\0'.
 802          */
 803         if (strlen(buf.data) + 1 != buf.len)
 804                 ereport(COMMERROR,
 805                                 (errcode(ERRCODE_PROTOCOL_VIOLATION),
 806                                  errmsg("invalid password packet size")));
 807
 808         /* Do not echo password to logs, for security. */
 809         ereport(DEBUG5,
 810                         (errmsg("received password packet")));
 811
 812         /*
 813          * Return the received string.  Note we do not attempt to do any
 814          * character-set conversion on it; since we don't yet know the
 815          * client's encoding, there wouldn't be much point.
 816          */
 817         return buf.data;
 818 }
 819
 820
 821 /*
 822  * Called when we have sent an authorization request for a password.
 823  * Get the response and check it.
 824  */
 825 static int
 826 recv_and_check_password_packet(Port *port)
 827 {
 828         char       *passwd;
 829         int                     result;
 830
 831         passwd = recv_password_packet(port);
 832
 833         if (passwd == NULL)
 834                 return STATUS_EOF;              /* client wouldn't send password */
 835
 836         result = md5_crypt_verify(port, port->user_name, passwd);
 837
 838         pfree(passwd);
 839
 840         return result;
 841 }