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fe-auth.c
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1 /*-------------------------------------------------------------------------
2  *
3  * fe-auth.c
4  * The front-end (client) authorization routines
5  *
6  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * IDENTIFICATION
10  * src/interfaces/libpq/fe-auth.c
11  *
12  *-------------------------------------------------------------------------
13  */
14 
15 /*
16  * INTERFACE ROUTINES
17  * frontend (client) routines:
18  * pg_fe_sendauth send authentication information
19  * pg_fe_getauthname get user's name according to the client side
20  * of the authentication system
21  */
22 
23 #include "postgres_fe.h"
24 
25 #ifdef WIN32
26 #include "win32.h"
27 #else
28 #include <unistd.h>
29 #include <fcntl.h>
30 #include <sys/param.h> /* for MAXHOSTNAMELEN on most */
31 #include <sys/socket.h>
32 #ifdef HAVE_SYS_UCRED_H
33 #include <sys/ucred.h>
34 #endif
35 #ifndef MAXHOSTNAMELEN
36 #include <netdb.h> /* for MAXHOSTNAMELEN on some */
37 #endif
38 #include <pwd.h>
39 #endif
40 
41 #include "common/md5.h"
42 #include "common/scram-common.h"
43 #include "fe-auth.h"
44 #include "libpq-fe.h"
45 
46 #ifdef ENABLE_GSS
47 /*
48  * GSSAPI authentication system.
49  */
50 
51 #include "fe-gssapi-common.h"
52 
53 /*
54  * Continue GSS authentication with next token as needed.
55  */
56 static int
57 pg_GSS_continue(PGconn *conn, int payloadlen)
58 {
59  OM_uint32 maj_stat,
60  min_stat,
61  lmin_s;
62  gss_buffer_desc ginbuf;
63  gss_buffer_desc goutbuf;
64 
65  /*
66  * On first call, there's no input token. On subsequent calls, read the
67  * input token into a GSS buffer.
68  */
69  if (conn->gctx != GSS_C_NO_CONTEXT)
70  {
71  ginbuf.length = payloadlen;
72  ginbuf.value = malloc(payloadlen);
73  if (!ginbuf.value)
74  {
76  libpq_gettext("out of memory allocating GSSAPI buffer (%d)\n"),
77  payloadlen);
78  return STATUS_ERROR;
79  }
80  if (pqGetnchar(ginbuf.value, payloadlen, conn))
81  {
82  /*
83  * Shouldn't happen, because the caller should've ensured that the
84  * whole message is already in the input buffer.
85  */
86  free(ginbuf.value);
87  return STATUS_ERROR;
88  }
89  }
90  else
91  {
92  ginbuf.length = 0;
93  ginbuf.value = NULL;
94  }
95 
96  maj_stat = gss_init_sec_context(&min_stat,
97  GSS_C_NO_CREDENTIAL,
98  &conn->gctx,
99  conn->gtarg_nam,
100  GSS_C_NO_OID,
101  GSS_C_MUTUAL_FLAG,
102  0,
103  GSS_C_NO_CHANNEL_BINDINGS,
104  (ginbuf.value == NULL) ? GSS_C_NO_BUFFER : &ginbuf,
105  NULL,
106  &goutbuf,
107  NULL,
108  NULL);
109 
110  if (ginbuf.value)
111  free(ginbuf.value);
112 
113  if (goutbuf.length != 0)
114  {
115  /*
116  * GSS generated data to send to the server. We don't care if it's the
117  * first or subsequent packet, just send the same kind of password
118  * packet.
119  */
120  if (pqPacketSend(conn, 'p',
121  goutbuf.value, goutbuf.length) != STATUS_OK)
122  {
123  gss_release_buffer(&lmin_s, &goutbuf);
124  return STATUS_ERROR;
125  }
126  }
127  gss_release_buffer(&lmin_s, &goutbuf);
128 
129  if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
130  {
131  pg_GSS_error(libpq_gettext("GSSAPI continuation error"),
132  conn,
133  maj_stat, min_stat);
134  gss_release_name(&lmin_s, &conn->gtarg_nam);
135  if (conn->gctx)
136  gss_delete_sec_context(&lmin_s, &conn->gctx, GSS_C_NO_BUFFER);
137  return STATUS_ERROR;
138  }
139 
140  if (maj_stat == GSS_S_COMPLETE)
141  gss_release_name(&lmin_s, &conn->gtarg_nam);
142 
143  return STATUS_OK;
144 }
145 
146 /*
147  * Send initial GSS authentication token
148  */
149 static int
150 pg_GSS_startup(PGconn *conn, int payloadlen)
151 {
152  int ret;
153  char *host = conn->connhost[conn->whichhost].host;
154 
155  if (!(host && host[0] != '\0'))
156  {
158  libpq_gettext("host name must be specified\n"));
159  return STATUS_ERROR;
160  }
161 
162  if (conn->gctx)
163  {
165  libpq_gettext("duplicate GSS authentication request\n"));
166  return STATUS_ERROR;
167  }
168 
169  ret = pg_GSS_load_servicename(conn);
170  if (ret != STATUS_OK)
171  return ret;
172 
173  /*
174  * Initial packet is the same as a continuation packet with no initial
175  * context.
176  */
177  conn->gctx = GSS_C_NO_CONTEXT;
178 
179  return pg_GSS_continue(conn, payloadlen);
180 }
181 #endif /* ENABLE_GSS */
182 
183 
184 #ifdef ENABLE_SSPI
185 /*
186  * SSPI authentication system (Windows only)
187  */
188 
189 static void
190 pg_SSPI_error(PGconn *conn, const char *mprefix, SECURITY_STATUS r)
191 {
192  char sysmsg[256];
193 
194  if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
195  FORMAT_MESSAGE_FROM_SYSTEM,
196  NULL, r, 0,
197  sysmsg, sizeof(sysmsg), NULL) == 0)
198  printfPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x\n",
199  mprefix, (unsigned int) r);
200  else
201  printfPQExpBuffer(&conn->errorMessage, "%s: %s (%x)\n",
202  mprefix, sysmsg, (unsigned int) r);
203 }
204 
205 /*
206  * Continue SSPI authentication with next token as needed.
207  */
208 static int
209 pg_SSPI_continue(PGconn *conn, int payloadlen)
210 {
211  SECURITY_STATUS r;
212  CtxtHandle newContext;
213  ULONG contextAttr;
214  SecBufferDesc inbuf;
215  SecBufferDesc outbuf;
216  SecBuffer OutBuffers[1];
217  SecBuffer InBuffers[1];
218  char *inputbuf = NULL;
219 
220  if (conn->sspictx != NULL)
221  {
222  /*
223  * On runs other than the first we have some data to send. Put this
224  * data in a SecBuffer type structure.
225  */
226  inputbuf = malloc(payloadlen);
227  if (!inputbuf)
228  {
230  libpq_gettext("out of memory allocating SSPI buffer (%d)\n"),
231  payloadlen);
232  return STATUS_ERROR;
233  }
234  if (pqGetnchar(inputbuf, payloadlen, conn))
235  {
236  /*
237  * Shouldn't happen, because the caller should've ensured that the
238  * whole message is already in the input buffer.
239  */
240  free(inputbuf);
241  return STATUS_ERROR;
242  }
243 
244  inbuf.ulVersion = SECBUFFER_VERSION;
245  inbuf.cBuffers = 1;
246  inbuf.pBuffers = InBuffers;
247  InBuffers[0].pvBuffer = inputbuf;
248  InBuffers[0].cbBuffer = payloadlen;
249  InBuffers[0].BufferType = SECBUFFER_TOKEN;
250  }
251 
252  OutBuffers[0].pvBuffer = NULL;
253  OutBuffers[0].BufferType = SECBUFFER_TOKEN;
254  OutBuffers[0].cbBuffer = 0;
255  outbuf.cBuffers = 1;
256  outbuf.pBuffers = OutBuffers;
257  outbuf.ulVersion = SECBUFFER_VERSION;
258 
259  r = InitializeSecurityContext(conn->sspicred,
260  conn->sspictx,
261  conn->sspitarget,
262  ISC_REQ_ALLOCATE_MEMORY,
263  0,
264  SECURITY_NETWORK_DREP,
265  (conn->sspictx == NULL) ? NULL : &inbuf,
266  0,
267  &newContext,
268  &outbuf,
269  &contextAttr,
270  NULL);
271 
272  /* we don't need the input anymore */
273  if (inputbuf)
274  free(inputbuf);
275 
276  if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED)
277  {
278  pg_SSPI_error(conn, libpq_gettext("SSPI continuation error"), r);
279 
280  return STATUS_ERROR;
281  }
282 
283  if (conn->sspictx == NULL)
284  {
285  /* On first run, transfer retrieved context handle */
286  conn->sspictx = malloc(sizeof(CtxtHandle));
287  if (conn->sspictx == NULL)
288  {
289  printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
290  return STATUS_ERROR;
291  }
292  memcpy(conn->sspictx, &newContext, sizeof(CtxtHandle));
293  }
294 
295  /*
296  * If SSPI returned any data to be sent to the server (as it normally
297  * would), send this data as a password packet.
298  */
299  if (outbuf.cBuffers > 0)
300  {
301  if (outbuf.cBuffers != 1)
302  {
303  /*
304  * This should never happen, at least not for Kerberos
305  * authentication. Keep check in case it shows up with other
306  * authentication methods later.
307  */
308  printfPQExpBuffer(&conn->errorMessage, "SSPI returned invalid number of output buffers\n");
309  return STATUS_ERROR;
310  }
311 
312  /*
313  * If the negotiation is complete, there may be zero bytes to send.
314  * The server is at this point not expecting any more data, so don't
315  * send it.
316  */
317  if (outbuf.pBuffers[0].cbBuffer > 0)
318  {
319  if (pqPacketSend(conn, 'p',
320  outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer))
321  {
322  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
323  return STATUS_ERROR;
324  }
325  }
326  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
327  }
328 
329  /* Cleanup is handled by the code in freePGconn() */
330  return STATUS_OK;
331 }
332 
333 /*
334  * Send initial SSPI authentication token.
335  * If use_negotiate is 0, use kerberos authentication package which is
336  * compatible with Unix. If use_negotiate is 1, use the negotiate package
337  * which supports both kerberos and NTLM, but is not compatible with Unix.
338  */
339 static int
340 pg_SSPI_startup(PGconn *conn, int use_negotiate, int payloadlen)
341 {
342  SECURITY_STATUS r;
343  TimeStamp expire;
344  char *host = conn->connhost[conn->whichhost].host;
345 
346  if (conn->sspictx)
347  {
349  libpq_gettext("duplicate SSPI authentication request\n"));
350  return STATUS_ERROR;
351  }
352 
353  /*
354  * Retrieve credentials handle
355  */
356  conn->sspicred = malloc(sizeof(CredHandle));
357  if (conn->sspicred == NULL)
358  {
359  printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
360  return STATUS_ERROR;
361  }
362 
363  r = AcquireCredentialsHandle(NULL,
364  use_negotiate ? "negotiate" : "kerberos",
365  SECPKG_CRED_OUTBOUND,
366  NULL,
367  NULL,
368  NULL,
369  NULL,
370  conn->sspicred,
371  &expire);
372  if (r != SEC_E_OK)
373  {
374  pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r);
375  free(conn->sspicred);
376  conn->sspicred = NULL;
377  return STATUS_ERROR;
378  }
379 
380  /*
381  * Compute target principal name. SSPI has a different format from GSSAPI,
382  * but not more complex. We can skip the @REALM part, because Windows will
383  * fill that in for us automatically.
384  */
385  if (!(host && host[0] != '\0'))
386  {
388  libpq_gettext("host name must be specified\n"));
389  return STATUS_ERROR;
390  }
391  conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2);
392  if (!conn->sspitarget)
393  {
394  printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
395  return STATUS_ERROR;
396  }
397  sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, host);
398 
399  /*
400  * Indicate that we're in SSPI authentication mode to make sure that
401  * pg_SSPI_continue is called next time in the negotiation.
402  */
403  conn->usesspi = 1;
404 
405  return pg_SSPI_continue(conn, payloadlen);
406 }
407 #endif /* ENABLE_SSPI */
408 
409 /*
410  * Initialize SASL authentication exchange.
411  */
412 static int
413 pg_SASL_init(PGconn *conn, int payloadlen)
414 {
415  char *initialresponse = NULL;
416  int initialresponselen;
417  bool done;
418  bool success;
419  const char *selected_mechanism;
420  PQExpBufferData mechanism_buf;
421  char *password;
422 
423  initPQExpBuffer(&mechanism_buf);
424 
425  if (conn->channel_binding[0] == 'r' && /* require */
426  !conn->ssl_in_use)
427  {
429  libpq_gettext("Channel binding required, but SSL not in use\n"));
430  goto error;
431  }
432 
433  if (conn->sasl_state)
434  {
436  libpq_gettext("duplicate SASL authentication request\n"));
437  goto error;
438  }
439 
440  /*
441  * Parse the list of SASL authentication mechanisms in the
442  * AuthenticationSASL message, and select the best mechanism that we
443  * support. SCRAM-SHA-256-PLUS and SCRAM-SHA-256 are the only ones
444  * supported at the moment, listed by order of decreasing importance.
445  */
446  selected_mechanism = NULL;
447  for (;;)
448  {
449  if (pqGets(&mechanism_buf, conn))
450  {
452  "fe_sendauth: invalid authentication request from server: invalid list of authentication mechanisms\n");
453  goto error;
454  }
455  if (PQExpBufferDataBroken(mechanism_buf))
456  goto oom_error;
457 
458  /* An empty string indicates end of list */
459  if (mechanism_buf.data[0] == '\0')
460  break;
461 
462  /*
463  * Select the mechanism to use. Pick SCRAM-SHA-256-PLUS over anything
464  * else if a channel binding type is set and if the client supports it
465  * (and did not set channel_binding=disable). Pick SCRAM-SHA-256 if
466  * nothing else has already been picked. If we add more mechanisms, a
467  * more refined priority mechanism might become necessary.
468  */
469  if (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0)
470  {
471  if (conn->ssl_in_use)
472  {
473  /* The server has offered SCRAM-SHA-256-PLUS. */
474 
475 #ifdef HAVE_PGTLS_GET_PEER_CERTIFICATE_HASH
476  /*
477  * The client supports channel binding, which is chosen if
478  * channel_binding is not disabled.
479  */
480  if (conn->channel_binding[0] != 'd') /* disable */
481  selected_mechanism = SCRAM_SHA_256_PLUS_NAME;
482 #else
483  /*
484  * The client does not support channel binding. If it is
485  * required, complain immediately instead of the error below
486  * which would be confusing as the server is publishing
487  * SCRAM-SHA-256-PLUS.
488  */
489  if (conn->channel_binding[0] == 'r') /* require */
490  {
492  libpq_gettext("channel binding is required, but client does not support it\n"));
493  goto error;
494  }
495 #endif
496  }
497  else
498  {
499  /*
500  * The server offered SCRAM-SHA-256-PLUS, but the connection
501  * is not SSL-encrypted. That's not sane. Perhaps SSL was
502  * stripped by a proxy? There's no point in continuing,
503  * because the server will reject the connection anyway if we
504  * try authenticate without channel binding even though both
505  * the client and server supported it. The SCRAM exchange
506  * checks for that, to prevent downgrade attacks.
507  */
509  libpq_gettext("server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection\n"));
510  goto error;
511  }
512  }
513  else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 &&
514  !selected_mechanism)
515  selected_mechanism = SCRAM_SHA_256_NAME;
516  }
517 
518  if (!selected_mechanism)
519  {
521  libpq_gettext("none of the server's SASL authentication mechanisms are supported\n"));
522  goto error;
523  }
524 
525  if (conn->channel_binding[0] == 'r' && /* require */
526  strcmp(selected_mechanism, SCRAM_SHA_256_PLUS_NAME) != 0)
527  {
529  libpq_gettext("channel binding is required, but server did not offer an authentication method that supports channel binding\n"));
530  goto error;
531  }
532 
533  /*
534  * Now that the SASL mechanism has been chosen for the exchange,
535  * initialize its state information.
536  */
537 
538  /*
539  * First, select the password to use for the exchange, complaining if
540  * there isn't one. Currently, all supported SASL mechanisms require a
541  * password, so we can just go ahead here without further distinction.
542  */
543  conn->password_needed = true;
544  password = conn->connhost[conn->whichhost].password;
545  if (password == NULL)
546  password = conn->pgpass;
547  if (password == NULL || password[0] == '\0')
548  {
551  goto error;
552  }
553 
554  /*
555  * Initialize the SASL state information with all the information gathered
556  * during the initial exchange.
557  *
558  * Note: Only tls-unique is supported for the moment.
559  */
560  conn->sasl_state = pg_fe_scram_init(conn,
561  password,
562  selected_mechanism);
563  if (!conn->sasl_state)
564  goto oom_error;
565 
566  /* Get the mechanism-specific Initial Client Response, if any */
568  NULL, -1,
569  &initialresponse, &initialresponselen,
570  &done, &success);
571 
572  if (done && !success)
573  goto error;
574 
575  /*
576  * Build a SASLInitialResponse message, and send it.
577  */
578  if (pqPutMsgStart('p', true, conn))
579  goto error;
580  if (pqPuts(selected_mechanism, conn))
581  goto error;
582  if (initialresponse)
583  {
584  if (pqPutInt(initialresponselen, 4, conn))
585  goto error;
586  if (pqPutnchar(initialresponse, initialresponselen, conn))
587  goto error;
588  }
589  if (pqPutMsgEnd(conn))
590  goto error;
591  if (pqFlush(conn))
592  goto error;
593 
594  termPQExpBuffer(&mechanism_buf);
595  if (initialresponse)
596  free(initialresponse);
597 
598  return STATUS_OK;
599 
600 error:
601  termPQExpBuffer(&mechanism_buf);
602  if (initialresponse)
603  free(initialresponse);
604  return STATUS_ERROR;
605 
606 oom_error:
607  termPQExpBuffer(&mechanism_buf);
608  if (initialresponse)
609  free(initialresponse);
611  libpq_gettext("out of memory\n"));
612  return STATUS_ERROR;
613 }
614 
615 /*
616  * Exchange a message for SASL communication protocol with the backend.
617  * This should be used after calling pg_SASL_init to set up the status of
618  * the protocol.
619  */
620 static int
621 pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
622 {
623  char *output;
624  int outputlen;
625  bool done;
626  bool success;
627  int res;
628  char *challenge;
629 
630  /* Read the SASL challenge from the AuthenticationSASLContinue message. */
631  challenge = malloc(payloadlen + 1);
632  if (!challenge)
633  {
635  libpq_gettext("out of memory allocating SASL buffer (%d)\n"),
636  payloadlen);
637  return STATUS_ERROR;
638  }
639 
640  if (pqGetnchar(challenge, payloadlen, conn))
641  {
642  free(challenge);
643  return STATUS_ERROR;
644  }
645  /* For safety and convenience, ensure the buffer is NULL-terminated. */
646  challenge[payloadlen] = '\0';
647 
649  challenge, payloadlen,
650  &output, &outputlen,
651  &done, &success);
652  free(challenge); /* don't need the input anymore */
653 
654  if (final && !done)
655  {
656  if (outputlen != 0)
657  free(output);
658 
660  libpq_gettext("AuthenticationSASLFinal received from server, but SASL authentication was not completed\n"));
661  return STATUS_ERROR;
662  }
663  if (outputlen != 0)
664  {
665  /*
666  * Send the SASL response to the server.
667  */
668  res = pqPacketSend(conn, 'p', output, outputlen);
669  free(output);
670 
671  if (res != STATUS_OK)
672  return STATUS_ERROR;
673  }
674 
675  if (done && !success)
676  return STATUS_ERROR;
677 
678  return STATUS_OK;
679 }
680 
681 /*
682  * Respond to AUTH_REQ_SCM_CREDS challenge.
683  *
684  * Note: this is dead code as of Postgres 9.1, because current backends will
685  * never send this challenge. But we must keep it as long as libpq needs to
686  * interoperate with pre-9.1 servers. It is believed to be needed only on
687  * Debian/kFreeBSD (ie, FreeBSD kernel with Linux userland, so that the
688  * getpeereid() function isn't provided by libc).
689  */
690 static int
692 {
693 #ifdef HAVE_STRUCT_CMSGCRED
694  char buf;
695  struct iovec iov;
696  struct msghdr msg;
697  struct cmsghdr *cmsg;
698  union
699  {
700  struct cmsghdr hdr;
701  unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))];
702  } cmsgbuf;
703 
704  /*
705  * The backend doesn't care what we send here, but it wants exactly one
706  * character to force recvmsg() to block and wait for us.
707  */
708  buf = '\0';
709  iov.iov_base = &buf;
710  iov.iov_len = 1;
711 
712  memset(&msg, 0, sizeof(msg));
713  msg.msg_iov = &iov;
714  msg.msg_iovlen = 1;
715 
716  /* We must set up a message that will be filled in by kernel */
717  memset(&cmsgbuf, 0, sizeof(cmsgbuf));
718  msg.msg_control = &cmsgbuf.buf;
719  msg.msg_controllen = sizeof(cmsgbuf.buf);
720  cmsg = CMSG_FIRSTHDR(&msg);
721  cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
722  cmsg->cmsg_level = SOL_SOCKET;
723  cmsg->cmsg_type = SCM_CREDS;
724 
725  if (sendmsg(conn->sock, &msg, 0) == -1)
726  {
727  char sebuf[PG_STRERROR_R_BUFLEN];
728 
730  "pg_local_sendauth: sendmsg: %s\n",
731  strerror_r(errno, sebuf, sizeof(sebuf)));
732  return STATUS_ERROR;
733  }
734  return STATUS_OK;
735 #else
737  libpq_gettext("SCM_CRED authentication method not supported\n"));
738  return STATUS_ERROR;
739 #endif
740 }
741 
742 static int
744 {
745  int ret;
746  char *crypt_pwd = NULL;
747  const char *pwd_to_send;
748  char md5Salt[4];
749 
750  /* Read the salt from the AuthenticationMD5Password message. */
751  if (areq == AUTH_REQ_MD5)
752  {
753  if (pqGetnchar(md5Salt, 4, conn))
754  return STATUS_ERROR; /* shouldn't happen */
755  }
756 
757  /* Encrypt the password if needed. */
758 
759  switch (areq)
760  {
761  case AUTH_REQ_MD5:
762  {
763  char *crypt_pwd2;
764 
765  /* Allocate enough space for two MD5 hashes */
766  crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
767  if (!crypt_pwd)
768  {
770  libpq_gettext("out of memory\n"));
771  return STATUS_ERROR;
772  }
773 
774  crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
775  if (!pg_md5_encrypt(password, conn->pguser,
776  strlen(conn->pguser), crypt_pwd2))
777  {
778  free(crypt_pwd);
779  return STATUS_ERROR;
780  }
781  if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt,
782  4, crypt_pwd))
783  {
784  free(crypt_pwd);
785  return STATUS_ERROR;
786  }
787 
788  pwd_to_send = crypt_pwd;
789  break;
790  }
791  case AUTH_REQ_PASSWORD:
792  pwd_to_send = password;
793  break;
794  default:
795  return STATUS_ERROR;
796  }
797  /* Packet has a message type as of protocol 3.0 */
798  if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
799  ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
800  else
801  ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
802  if (crypt_pwd)
803  free(crypt_pwd);
804  return ret;
805 }
806 
807 /*
808  * Verify that the authentication request is expected, given the connection
809  * parameters. This is especially important when the client wishes to
810  * authenticate the server before any sensitive information is exchanged.
811  */
812 static bool
814 {
815  bool result = true;
816 
817  /*
818  * When channel_binding=require, we must protect against two cases: (1) we
819  * must not respond to non-SASL authentication requests, which might leak
820  * information such as the client's password; and (2) even if we receive
821  * AUTH_REQ_OK, we still must ensure that channel binding has happened in
822  * order to authenticate the server.
823  */
824  if (conn->channel_binding[0] == 'r' /* require */ )
825  {
826  switch (areq)
827  {
828  case AUTH_REQ_SASL:
829  case AUTH_REQ_SASL_CONT:
830  case AUTH_REQ_SASL_FIN:
831  break;
832  case AUTH_REQ_OK:
834  {
836  libpq_gettext("Channel binding required, but server authenticated client without channel binding\n"));
837  result = false;
838  }
839  break;
840  default:
842  libpq_gettext("Channel binding required but not supported by server's authentication request\n"));
843  result = false;
844  break;
845  }
846  }
847 
848  return result;
849 }
850 
851 /*
852  * pg_fe_sendauth
853  * client demux routine for processing an authentication request
854  *
855  * The server has sent us an authentication challenge (or OK). Send an
856  * appropriate response. The caller has ensured that the whole message is
857  * now in the input buffer, and has already read the type and length of
858  * it. We are responsible for reading any remaining extra data, specific
859  * to the authentication method. 'payloadlen' is the remaining length in
860  * the message.
861  */
862 int
863 pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
864 {
865  if (!check_expected_areq(areq, conn))
866  return STATUS_ERROR;
867 
868  switch (areq)
869  {
870  case AUTH_REQ_OK:
871  break;
872 
873  case AUTH_REQ_KRB4:
875  libpq_gettext("Kerberos 4 authentication not supported\n"));
876  return STATUS_ERROR;
877 
878  case AUTH_REQ_KRB5:
880  libpq_gettext("Kerberos 5 authentication not supported\n"));
881  return STATUS_ERROR;
882 
883 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
884  case AUTH_REQ_GSS:
885 #if !defined(ENABLE_SSPI)
886  /* no native SSPI, so use GSSAPI library for it */
887  case AUTH_REQ_SSPI:
888 #endif
889  {
890  int r;
891 
892  pglock_thread();
893 
894  /*
895  * If we have both GSS and SSPI support compiled in, use SSPI
896  * support by default. This is overridable by a connection
897  * string parameter. Note that when using SSPI we still leave
898  * the negotiate parameter off, since we want SSPI to use the
899  * GSSAPI kerberos protocol. For actual SSPI negotiate
900  * protocol, we use AUTH_REQ_SSPI.
901  */
902 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
903  if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
904  r = pg_GSS_startup(conn, payloadlen);
905  else
906  r = pg_SSPI_startup(conn, 0, payloadlen);
907 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
908  r = pg_GSS_startup(conn, payloadlen);
909 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
910  r = pg_SSPI_startup(conn, 0, payloadlen);
911 #endif
912  if (r != STATUS_OK)
913  {
914  /* Error message already filled in. */
915  pgunlock_thread();
916  return STATUS_ERROR;
917  }
918  pgunlock_thread();
919  }
920  break;
921 
922  case AUTH_REQ_GSS_CONT:
923  {
924  int r;
925 
926  pglock_thread();
927 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
928  if (conn->usesspi)
929  r = pg_SSPI_continue(conn, payloadlen);
930  else
931  r = pg_GSS_continue(conn, payloadlen);
932 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
933  r = pg_GSS_continue(conn, payloadlen);
934 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
935  r = pg_SSPI_continue(conn, payloadlen);
936 #endif
937  if (r != STATUS_OK)
938  {
939  /* Error message already filled in. */
940  pgunlock_thread();
941  return STATUS_ERROR;
942  }
943  pgunlock_thread();
944  }
945  break;
946 #else /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
947  /* No GSSAPI *or* SSPI support */
948  case AUTH_REQ_GSS:
949  case AUTH_REQ_GSS_CONT:
951  libpq_gettext("GSSAPI authentication not supported\n"));
952  return STATUS_ERROR;
953 #endif /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
954 
955 #ifdef ENABLE_SSPI
956  case AUTH_REQ_SSPI:
957 
958  /*
959  * SSPI has its own startup message so libpq can decide which
960  * method to use. Indicate to pg_SSPI_startup that we want SSPI
961  * negotiation instead of Kerberos.
962  */
963  pglock_thread();
964  if (pg_SSPI_startup(conn, 1, payloadlen) != STATUS_OK)
965  {
966  /* Error message already filled in. */
967  pgunlock_thread();
968  return STATUS_ERROR;
969  }
970  pgunlock_thread();
971  break;
972 #else
973 
974  /*
975  * No SSPI support. However, if we have GSSAPI but not SSPI
976  * support, AUTH_REQ_SSPI will have been handled in the codepath
977  * for AUTH_REQ_GSS above, so don't duplicate the case label in
978  * that case.
979  */
980 #if !defined(ENABLE_GSS)
981  case AUTH_REQ_SSPI:
983  libpq_gettext("SSPI authentication not supported\n"));
984  return STATUS_ERROR;
985 #endif /* !define(ENABLE_GSS) */
986 #endif /* ENABLE_SSPI */
987 
988 
989  case AUTH_REQ_CRYPT:
991  libpq_gettext("Crypt authentication not supported\n"));
992  return STATUS_ERROR;
993 
994  case AUTH_REQ_MD5:
995  case AUTH_REQ_PASSWORD:
996  {
997  char *password;
998 
999  conn->password_needed = true;
1000  password = conn->connhost[conn->whichhost].password;
1001  if (password == NULL)
1002  password = conn->pgpass;
1003  if (password == NULL || password[0] == '\0')
1004  {
1007  return STATUS_ERROR;
1008  }
1009  if (pg_password_sendauth(conn, password, areq) != STATUS_OK)
1010  {
1012  "fe_sendauth: error sending password authentication\n");
1013  return STATUS_ERROR;
1014  }
1015  break;
1016  }
1017 
1018  case AUTH_REQ_SASL:
1019 
1020  /*
1021  * The request contains the name (as assigned by IANA) of the
1022  * authentication mechanism.
1023  */
1024  if (pg_SASL_init(conn, payloadlen) != STATUS_OK)
1025  {
1026  /* pg_SASL_init already set the error message */
1027  return STATUS_ERROR;
1028  }
1029  break;
1030 
1031  case AUTH_REQ_SASL_CONT:
1032  case AUTH_REQ_SASL_FIN:
1033  if (conn->sasl_state == NULL)
1034  {
1036  "fe_sendauth: invalid authentication request from server: AUTH_REQ_SASL_CONT without AUTH_REQ_SASL\n");
1037  return STATUS_ERROR;
1038  }
1039  if (pg_SASL_continue(conn, payloadlen,
1040  (areq == AUTH_REQ_SASL_FIN)) != STATUS_OK)
1041  {
1042  /* Use error message, if set already */
1043  if (conn->errorMessage.len == 0)
1045  "fe_sendauth: error in SASL authentication\n");
1046  return STATUS_ERROR;
1047  }
1048  break;
1049 
1050  case AUTH_REQ_SCM_CREDS:
1051  if (pg_local_sendauth(conn) != STATUS_OK)
1052  return STATUS_ERROR;
1053  break;
1054 
1055  default:
1057  libpq_gettext("authentication method %u not supported\n"), areq);
1058  return STATUS_ERROR;
1059  }
1060 
1061  return STATUS_OK;
1062 }
1063 
1064 
1065 /*
1066  * pg_fe_getauthname
1067  *
1068  * Returns a pointer to malloc'd space containing whatever name the user
1069  * has authenticated to the system. If there is an error, return NULL,
1070  * and put a suitable error message in *errorMessage if that's not NULL.
1071  */
1072 char *
1074 {
1075  char *result = NULL;
1076  const char *name = NULL;
1077 
1078 #ifdef WIN32
1079  /* Microsoft recommends buffer size of UNLEN+1, where UNLEN = 256 */
1080  char username[256 + 1];
1081  DWORD namesize = sizeof(username);
1082 #else
1083  uid_t user_id = geteuid();
1084  char pwdbuf[BUFSIZ];
1085  struct passwd pwdstr;
1086  struct passwd *pw = NULL;
1087  int pwerr;
1088 #endif
1089 
1090  /*
1091  * Some users are using configure --enable-thread-safety-force, so we
1092  * might as well do the locking within our library to protect
1093  * pqGetpwuid(). In fact, application developers can use getpwuid() in
1094  * their application if they use the locking call we provide, or install
1095  * their own locking function using PQregisterThreadLock().
1096  */
1097  pglock_thread();
1098 
1099 #ifdef WIN32
1100  if (GetUserName(username, &namesize))
1101  name = username;
1102  else if (errorMessage)
1103  printfPQExpBuffer(errorMessage,
1104  libpq_gettext("user name lookup failure: error code %lu\n"),
1105  GetLastError());
1106 #else
1107  pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw);
1108  if (pw != NULL)
1109  name = pw->pw_name;
1110  else if (errorMessage)
1111  {
1112  if (pwerr != 0)
1113  printfPQExpBuffer(errorMessage,
1114  libpq_gettext("could not look up local user ID %d: %s\n"),
1115  (int) user_id,
1116  strerror_r(pwerr, pwdbuf, sizeof(pwdbuf)));
1117  else
1118  printfPQExpBuffer(errorMessage,
1119  libpq_gettext("local user with ID %d does not exist\n"),
1120  (int) user_id);
1121  }
1122 #endif
1123 
1124  if (name)
1125  {
1126  result = strdup(name);
1127  if (result == NULL && errorMessage)
1128  printfPQExpBuffer(errorMessage,
1129  libpq_gettext("out of memory\n"));
1130  }
1131 
1132  pgunlock_thread();
1133 
1134  return result;
1135 }
1136 
1137 
1138 /*
1139  * PQencryptPassword -- exported routine to encrypt a password with MD5
1140  *
1141  * This function is equivalent to calling PQencryptPasswordConn with
1142  * "md5" as the encryption method, except that this doesn't require
1143  * a connection object. This function is deprecated, use
1144  * PQencryptPasswordConn instead.
1145  */
1146 char *
1147 PQencryptPassword(const char *passwd, const char *user)
1148 {
1149  char *crypt_pwd;
1150 
1151  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1152  if (!crypt_pwd)
1153  return NULL;
1154 
1155  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1156  {
1157  free(crypt_pwd);
1158  return NULL;
1159  }
1160 
1161  return crypt_pwd;
1162 }
1163 
1164 /*
1165  * PQencryptPasswordConn -- exported routine to encrypt a password
1166  *
1167  * This is intended to be used by client applications that wish to send
1168  * commands like ALTER USER joe PASSWORD 'pwd'. The password need not
1169  * be sent in cleartext if it is encrypted on the client side. This is
1170  * good because it ensures the cleartext password won't end up in logs,
1171  * pg_stat displays, etc. We export the function so that clients won't
1172  * be dependent on low-level details like whether the encryption is MD5
1173  * or something else.
1174  *
1175  * Arguments are a connection object, the cleartext password, the SQL
1176  * name of the user it is for, and a string indicating the algorithm to
1177  * use for encrypting the password. If algorithm is NULL, this queries
1178  * the server for the current 'password_encryption' value. If you wish
1179  * to avoid that, e.g. to avoid blocking, you can execute
1180  * 'show password_encryption' yourself before calling this function, and
1181  * pass it as the algorithm.
1182  *
1183  * Return value is a malloc'd string. The client may assume the string
1184  * doesn't contain any special characters that would require escaping.
1185  * On error, an error message is stored in the connection object, and
1186  * returns NULL.
1187  */
1188 char *
1189 PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user,
1190  const char *algorithm)
1191 {
1192 #define MAX_ALGORITHM_NAME_LEN 50
1193  char algobuf[MAX_ALGORITHM_NAME_LEN + 1];
1194  char *crypt_pwd = NULL;
1195 
1196  if (!conn)
1197  return NULL;
1198 
1199  /* If no algorithm was given, ask the server. */
1200  if (algorithm == NULL)
1201  {
1202  PGresult *res;
1203  char *val;
1204 
1205  res = PQexec(conn, "show password_encryption");
1206  if (res == NULL)
1207  {
1208  /* PQexec() should've set conn->errorMessage already */
1209  return NULL;
1210  }
1211  if (PQresultStatus(res) != PGRES_TUPLES_OK)
1212  {
1213  /* PQexec() should've set conn->errorMessage already */
1214  PQclear(res);
1215  return NULL;
1216  }
1217  if (PQntuples(res) != 1 || PQnfields(res) != 1)
1218  {
1219  PQclear(res);
1221  libpq_gettext("unexpected shape of result set returned for SHOW\n"));
1222  return NULL;
1223  }
1224  val = PQgetvalue(res, 0, 0);
1225 
1226  if (strlen(val) > MAX_ALGORITHM_NAME_LEN)
1227  {
1228  PQclear(res);
1230  libpq_gettext("password_encryption value too long\n"));
1231  return NULL;
1232  }
1233  strcpy(algobuf, val);
1234  PQclear(res);
1235 
1236  algorithm = algobuf;
1237  }
1238 
1239  /*
1240  * Also accept "on" and "off" as aliases for "md5", because
1241  * password_encryption was a boolean before PostgreSQL 10. We refuse to
1242  * send the password in plaintext even if it was "off".
1243  */
1244  if (strcmp(algorithm, "on") == 0 ||
1245  strcmp(algorithm, "off") == 0)
1246  algorithm = "md5";
1247 
1248  /*
1249  * Ok, now we know what algorithm to use
1250  */
1251  if (strcmp(algorithm, "scram-sha-256") == 0)
1252  {
1253  crypt_pwd = pg_fe_scram_build_secret(passwd);
1254  }
1255  else if (strcmp(algorithm, "md5") == 0)
1256  {
1257  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1258  if (crypt_pwd)
1259  {
1260  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1261  {
1262  free(crypt_pwd);
1263  crypt_pwd = NULL;
1264  }
1265  }
1266  }
1267  else
1268  {
1270  libpq_gettext("unrecognized password encryption algorithm \"%s\"\n"),
1271  algorithm);
1272  return NULL;
1273  }
1274 
1275  if (!crypt_pwd)
1277  libpq_gettext("out of memory\n"));
1278 
1279  return crypt_pwd;
1280 }
int pqFlush(PGconn *conn)
Definition: fe-misc.c:997
static char password[100]
Definition: streamutil.c:53
int PQnfields(const PGresult *res)
Definition: fe-exec.c:2777
#define AUTH_REQ_SSPI
Definition: pqcomm.h:174
void printfPQExpBuffer(PQExpBuffer str, const char *fmt,...)
Definition: pqexpbuffer.c:237
char * PQgetvalue(const PGresult *res, int tup_num, int field_num)
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static void error(void)
Definition: sql-dyntest.c:147
#define SCRAM_SHA_256_NAME
Definition: scram-common.h:19
static int pg_local_sendauth(PGconn *conn)
Definition: fe-auth.c:691
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#define AUTH_REQ_SASL_FIN
Definition: pqcomm.h:177
int pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
Definition: fe-auth.c:863
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Definition: pqexpbuffer.c:131
bool password_needed
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#define AUTH_REQ_OK
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#define AUTH_REQ_GSS
Definition: pqcomm.h:172
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#define PG_STRERROR_R_BUFLEN
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char * host
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Definition: fe-misc.c:518
static int pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
Definition: fe-auth.c:743
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int pg_strcasecmp(const char *s1, const char *s2)
Definition: pgstrcasecmp.c:36
int pqGetnchar(char *s, size_t len, PGconn *conn)
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#define PG_PROTOCOL_MAJOR(v)
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int PQntuples(const PGresult *res)
Definition: fe-exec.c:2769
uint32 AuthRequest
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#define AUTH_REQ_MD5
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ExecStatusType PQresultStatus(const PGresult *res)
Definition: fe-exec.c:2692
static int pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
Definition: fe-auth.c:621
#define malloc(a)
Definition: header.h:50
int pqPutInt(int value, size_t bytes, PGconn *conn)
Definition: fe-misc.c:306
#define MAX_ALGORITHM_NAME_LEN
#define sprintf
Definition: port.h:194
bool pg_md5_encrypt(const char *passwd, const char *salt, size_t salt_len, char *buf)
Definition: md5.c:323
PGconn * conn
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pg_conn_host * connhost
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Definition: libpq-int.h:469
void * sasl_state
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#define SCRAM_SHA_256_PLUS_NAME
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char * channel_binding
Definition: libpq-int.h:350
int pqPuts(const char *s, PGconn *conn)
Definition: fe-misc.c:178
#define AUTH_REQ_CRYPT
Definition: pqcomm.h:169
char * pguser
Definition: libpq-int.h:347
#define STATUS_OK
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#define AUTH_REQ_PASSWORD
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pgsocket sock
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char * pg_fe_getauthname(PQExpBuffer errorMessage)
Definition: fe-auth.c:1073
PQExpBufferData errorMessage
Definition: libpq-int.h:511
#define AUTH_REQ_KRB5
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static char * username
Definition: initdb.c:133
#define AUTH_REQ_SASL_CONT
Definition: pqcomm.h:176
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Definition: fe-exec.c:694
#define MD5_PASSWD_LEN
Definition: md5.h:20
#define free(a)
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#define PQExpBufferDataBroken(buf)
Definition: pqexpbuffer.h:67
int pqPutnchar(const char *s, size_t len, PGconn *conn)
Definition: fe-misc.c:245
#define AUTH_REQ_KRB4
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char * pgpass
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#define strerror_r
Definition: port.h:209
ProtocolVersion pversion
Definition: libpq-int.h:411
char * PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user, const char *algorithm)
Definition: fe-auth.c:1189
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Definition: win32_port.h:230
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int pqPutMsgEnd(PGconn *conn)
Definition: fe-misc.c:586
void * pg_fe_scram_init(PGconn *conn, const char *password, const char *sasl_mechanism)
Definition: fe-auth-scram.c:75
const char * name
Definition: encode.c:521
#define AUTH_REQ_SASL
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#define AUTH_REQ_GSS_CONT
Definition: pqcomm.h:173
int pqGetpwuid(uid_t uid, struct passwd *resultbuf, char *buffer, size_t buflen, struct passwd **result)
Definition: thread.c:68
static char * user
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Definition: fe-connect.c:4464
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Definition: fe-auth.c:813
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Definition: fe-exec.c:1939
static bool success
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