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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) 1996-2021, 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  appendPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x\n",
199  mprefix, (unsigned int) r);
200  else
201  appendPQExpBuffer(&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  {
290  libpq_gettext("out of memory\n"));
291  return STATUS_ERROR;
292  }
293  memcpy(conn->sspictx, &newContext, sizeof(CtxtHandle));
294  }
295 
296  /*
297  * If SSPI returned any data to be sent to the server (as it normally
298  * would), send this data as a password packet.
299  */
300  if (outbuf.cBuffers > 0)
301  {
302  if (outbuf.cBuffers != 1)
303  {
304  /*
305  * This should never happen, at least not for Kerberos
306  * authentication. Keep check in case it shows up with other
307  * authentication methods later.
308  */
310  "SSPI returned invalid number of output buffers\n");
311  return STATUS_ERROR;
312  }
313 
314  /*
315  * If the negotiation is complete, there may be zero bytes to send.
316  * The server is at this point not expecting any more data, so don't
317  * send it.
318  */
319  if (outbuf.pBuffers[0].cbBuffer > 0)
320  {
321  if (pqPacketSend(conn, 'p',
322  outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer))
323  {
324  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
325  return STATUS_ERROR;
326  }
327  }
328  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
329  }
330 
331  /* Cleanup is handled by the code in freePGconn() */
332  return STATUS_OK;
333 }
334 
335 /*
336  * Send initial SSPI authentication token.
337  * If use_negotiate is 0, use kerberos authentication package which is
338  * compatible with Unix. If use_negotiate is 1, use the negotiate package
339  * which supports both kerberos and NTLM, but is not compatible with Unix.
340  */
341 static int
342 pg_SSPI_startup(PGconn *conn, int use_negotiate, int payloadlen)
343 {
344  SECURITY_STATUS r;
345  TimeStamp expire;
346  char *host = conn->connhost[conn->whichhost].host;
347 
348  if (conn->sspictx)
349  {
351  libpq_gettext("duplicate SSPI authentication request\n"));
352  return STATUS_ERROR;
353  }
354 
355  /*
356  * Retrieve credentials handle
357  */
358  conn->sspicred = malloc(sizeof(CredHandle));
359  if (conn->sspicred == NULL)
360  {
362  libpq_gettext("out of memory\n"));
363  return STATUS_ERROR;
364  }
365 
366  r = AcquireCredentialsHandle(NULL,
367  use_negotiate ? "negotiate" : "kerberos",
368  SECPKG_CRED_OUTBOUND,
369  NULL,
370  NULL,
371  NULL,
372  NULL,
373  conn->sspicred,
374  &expire);
375  if (r != SEC_E_OK)
376  {
377  pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r);
378  free(conn->sspicred);
379  conn->sspicred = NULL;
380  return STATUS_ERROR;
381  }
382 
383  /*
384  * Compute target principal name. SSPI has a different format from GSSAPI,
385  * but not more complex. We can skip the @REALM part, because Windows will
386  * fill that in for us automatically.
387  */
388  if (!(host && host[0] != '\0'))
389  {
391  libpq_gettext("host name must be specified\n"));
392  return STATUS_ERROR;
393  }
394  conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2);
395  if (!conn->sspitarget)
396  {
398  libpq_gettext("out of memory\n"));
399  return STATUS_ERROR;
400  }
401  sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, host);
402 
403  /*
404  * Indicate that we're in SSPI authentication mode to make sure that
405  * pg_SSPI_continue is called next time in the negotiation.
406  */
407  conn->usesspi = 1;
408 
409  return pg_SSPI_continue(conn, payloadlen);
410 }
411 #endif /* ENABLE_SSPI */
412 
413 /*
414  * Initialize SASL authentication exchange.
415  */
416 static int
417 pg_SASL_init(PGconn *conn, int payloadlen)
418 {
419  char *initialresponse = NULL;
420  int initialresponselen;
421  bool done;
422  bool success;
423  const char *selected_mechanism;
424  PQExpBufferData mechanism_buf;
425  char *password;
426 
427  initPQExpBuffer(&mechanism_buf);
428 
429  if (conn->channel_binding[0] == 'r' && /* require */
430  !conn->ssl_in_use)
431  {
433  libpq_gettext("channel binding required, but SSL not in use\n"));
434  goto error;
435  }
436 
437  if (conn->sasl_state)
438  {
440  libpq_gettext("duplicate SASL authentication request\n"));
441  goto error;
442  }
443 
444  /*
445  * Parse the list of SASL authentication mechanisms in the
446  * AuthenticationSASL message, and select the best mechanism that we
447  * support. SCRAM-SHA-256-PLUS and SCRAM-SHA-256 are the only ones
448  * supported at the moment, listed by order of decreasing importance.
449  */
450  selected_mechanism = NULL;
451  for (;;)
452  {
453  if (pqGets(&mechanism_buf, conn))
454  {
456  "fe_sendauth: invalid authentication request from server: invalid list of authentication mechanisms\n");
457  goto error;
458  }
459  if (PQExpBufferDataBroken(mechanism_buf))
460  goto oom_error;
461 
462  /* An empty string indicates end of list */
463  if (mechanism_buf.data[0] == '\0')
464  break;
465 
466  /*
467  * Select the mechanism to use. Pick SCRAM-SHA-256-PLUS over anything
468  * else if a channel binding type is set and if the client supports it
469  * (and did not set channel_binding=disable). Pick SCRAM-SHA-256 if
470  * nothing else has already been picked. If we add more mechanisms, a
471  * more refined priority mechanism might become necessary.
472  */
473  if (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0)
474  {
475  if (conn->ssl_in_use)
476  {
477  /* The server has offered SCRAM-SHA-256-PLUS. */
478 
479 #ifdef HAVE_PGTLS_GET_PEER_CERTIFICATE_HASH
480  /*
481  * The client supports channel binding, which is chosen if
482  * channel_binding is not disabled.
483  */
484  if (conn->channel_binding[0] != 'd') /* disable */
485  selected_mechanism = SCRAM_SHA_256_PLUS_NAME;
486 #else
487  /*
488  * The client does not support channel binding. If it is
489  * required, complain immediately instead of the error below
490  * which would be confusing as the server is publishing
491  * SCRAM-SHA-256-PLUS.
492  */
493  if (conn->channel_binding[0] == 'r') /* require */
494  {
496  libpq_gettext("channel binding is required, but client does not support it\n"));
497  goto error;
498  }
499 #endif
500  }
501  else
502  {
503  /*
504  * The server offered SCRAM-SHA-256-PLUS, but the connection
505  * is not SSL-encrypted. That's not sane. Perhaps SSL was
506  * stripped by a proxy? There's no point in continuing,
507  * because the server will reject the connection anyway if we
508  * try authenticate without channel binding even though both
509  * the client and server supported it. The SCRAM exchange
510  * checks for that, to prevent downgrade attacks.
511  */
513  libpq_gettext("server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection\n"));
514  goto error;
515  }
516  }
517  else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 &&
518  !selected_mechanism)
519  selected_mechanism = SCRAM_SHA_256_NAME;
520  }
521 
522  if (!selected_mechanism)
523  {
525  libpq_gettext("none of the server's SASL authentication mechanisms are supported\n"));
526  goto error;
527  }
528 
529  if (conn->channel_binding[0] == 'r' && /* require */
530  strcmp(selected_mechanism, SCRAM_SHA_256_PLUS_NAME) != 0)
531  {
533  libpq_gettext("channel binding is required, but server did not offer an authentication method that supports channel binding\n"));
534  goto error;
535  }
536 
537  /*
538  * Now that the SASL mechanism has been chosen for the exchange,
539  * initialize its state information.
540  */
541 
542  /*
543  * First, select the password to use for the exchange, complaining if
544  * there isn't one. Currently, all supported SASL mechanisms require a
545  * password, so we can just go ahead here without further distinction.
546  */
547  conn->password_needed = true;
548  password = conn->connhost[conn->whichhost].password;
549  if (password == NULL)
550  password = conn->pgpass;
551  if (password == NULL || password[0] == '\0')
552  {
555  goto error;
556  }
557 
558  /*
559  * Initialize the SASL state information with all the information gathered
560  * during the initial exchange.
561  *
562  * Note: Only tls-unique is supported for the moment.
563  */
564  conn->sasl_state = pg_fe_scram_init(conn,
565  password,
566  selected_mechanism);
567  if (!conn->sasl_state)
568  goto oom_error;
569 
570  /* Get the mechanism-specific Initial Client Response, if any */
572  NULL, -1,
573  &initialresponse, &initialresponselen,
574  &done, &success);
575 
576  if (done && !success)
577  goto error;
578 
579  /*
580  * Build a SASLInitialResponse message, and send it.
581  */
582  if (pqPutMsgStart('p', conn))
583  goto error;
584  if (pqPuts(selected_mechanism, conn))
585  goto error;
586  if (initialresponse)
587  {
588  if (pqPutInt(initialresponselen, 4, conn))
589  goto error;
590  if (pqPutnchar(initialresponse, initialresponselen, conn))
591  goto error;
592  }
593  if (pqPutMsgEnd(conn))
594  goto error;
595  if (pqFlush(conn))
596  goto error;
597 
598  termPQExpBuffer(&mechanism_buf);
599  if (initialresponse)
600  free(initialresponse);
601 
602  return STATUS_OK;
603 
604 error:
605  termPQExpBuffer(&mechanism_buf);
606  if (initialresponse)
607  free(initialresponse);
608  return STATUS_ERROR;
609 
610 oom_error:
611  termPQExpBuffer(&mechanism_buf);
612  if (initialresponse)
613  free(initialresponse);
615  libpq_gettext("out of memory\n"));
616  return STATUS_ERROR;
617 }
618 
619 /*
620  * Exchange a message for SASL communication protocol with the backend.
621  * This should be used after calling pg_SASL_init to set up the status of
622  * the protocol.
623  */
624 static int
625 pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
626 {
627  char *output;
628  int outputlen;
629  bool done;
630  bool success;
631  int res;
632  char *challenge;
633 
634  /* Read the SASL challenge from the AuthenticationSASLContinue message. */
635  challenge = malloc(payloadlen + 1);
636  if (!challenge)
637  {
639  libpq_gettext("out of memory allocating SASL buffer (%d)\n"),
640  payloadlen);
641  return STATUS_ERROR;
642  }
643 
644  if (pqGetnchar(challenge, payloadlen, conn))
645  {
646  free(challenge);
647  return STATUS_ERROR;
648  }
649  /* For safety and convenience, ensure the buffer is NULL-terminated. */
650  challenge[payloadlen] = '\0';
651 
653  challenge, payloadlen,
654  &output, &outputlen,
655  &done, &success);
656  free(challenge); /* don't need the input anymore */
657 
658  if (final && !done)
659  {
660  if (outputlen != 0)
661  free(output);
662 
664  libpq_gettext("AuthenticationSASLFinal received from server, but SASL authentication was not completed\n"));
665  return STATUS_ERROR;
666  }
667  if (outputlen != 0)
668  {
669  /*
670  * Send the SASL response to the server.
671  */
672  res = pqPacketSend(conn, 'p', output, outputlen);
673  free(output);
674 
675  if (res != STATUS_OK)
676  return STATUS_ERROR;
677  }
678 
679  if (done && !success)
680  return STATUS_ERROR;
681 
682  return STATUS_OK;
683 }
684 
685 /*
686  * Respond to AUTH_REQ_SCM_CREDS challenge.
687  *
688  * Note: this is dead code as of Postgres 9.1, because current backends will
689  * never send this challenge. But we must keep it as long as libpq needs to
690  * interoperate with pre-9.1 servers. It is believed to be needed only on
691  * Debian/kFreeBSD (ie, FreeBSD kernel with Linux userland, so that the
692  * getpeereid() function isn't provided by libc).
693  */
694 static int
696 {
697 #ifdef HAVE_STRUCT_CMSGCRED
698  char buf;
699  struct iovec iov;
700  struct msghdr msg;
701  struct cmsghdr *cmsg;
702  union
703  {
704  struct cmsghdr hdr;
705  unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))];
706  } cmsgbuf;
707 
708  /*
709  * The backend doesn't care what we send here, but it wants exactly one
710  * character to force recvmsg() to block and wait for us.
711  */
712  buf = '\0';
713  iov.iov_base = &buf;
714  iov.iov_len = 1;
715 
716  memset(&msg, 0, sizeof(msg));
717  msg.msg_iov = &iov;
718  msg.msg_iovlen = 1;
719 
720  /* We must set up a message that will be filled in by kernel */
721  memset(&cmsgbuf, 0, sizeof(cmsgbuf));
722  msg.msg_control = &cmsgbuf.buf;
723  msg.msg_controllen = sizeof(cmsgbuf.buf);
724  cmsg = CMSG_FIRSTHDR(&msg);
725  cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
726  cmsg->cmsg_level = SOL_SOCKET;
727  cmsg->cmsg_type = SCM_CREDS;
728 
729  if (sendmsg(conn->sock, &msg, 0) == -1)
730  {
731  char sebuf[PG_STRERROR_R_BUFLEN];
732 
734  "pg_local_sendauth: sendmsg: %s\n",
735  strerror_r(errno, sebuf, sizeof(sebuf)));
736  return STATUS_ERROR;
737  }
738  return STATUS_OK;
739 #else
741  libpq_gettext("SCM_CRED authentication method not supported\n"));
742  return STATUS_ERROR;
743 #endif
744 }
745 
746 static int
748 {
749  int ret;
750  char *crypt_pwd = NULL;
751  const char *pwd_to_send;
752  char md5Salt[4];
753 
754  /* Read the salt from the AuthenticationMD5Password message. */
755  if (areq == AUTH_REQ_MD5)
756  {
757  if (pqGetnchar(md5Salt, 4, conn))
758  return STATUS_ERROR; /* shouldn't happen */
759  }
760 
761  /* Encrypt the password if needed. */
762 
763  switch (areq)
764  {
765  case AUTH_REQ_MD5:
766  {
767  char *crypt_pwd2;
768 
769  /* Allocate enough space for two MD5 hashes */
770  crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
771  if (!crypt_pwd)
772  {
774  libpq_gettext("out of memory\n"));
775  return STATUS_ERROR;
776  }
777 
778  crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
779  if (!pg_md5_encrypt(password, conn->pguser,
780  strlen(conn->pguser), crypt_pwd2))
781  {
782  free(crypt_pwd);
783  return STATUS_ERROR;
784  }
785  if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt,
786  4, crypt_pwd))
787  {
788  free(crypt_pwd);
789  return STATUS_ERROR;
790  }
791 
792  pwd_to_send = crypt_pwd;
793  break;
794  }
795  case AUTH_REQ_PASSWORD:
796  pwd_to_send = password;
797  break;
798  default:
799  return STATUS_ERROR;
800  }
801  ret = pqPacketSend(conn, 'p', 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  int oldmsglen;
866 
867  if (!check_expected_areq(areq, conn))
868  return STATUS_ERROR;
869 
870  switch (areq)
871  {
872  case AUTH_REQ_OK:
873  break;
874 
875  case AUTH_REQ_KRB4:
877  libpq_gettext("Kerberos 4 authentication not supported\n"));
878  return STATUS_ERROR;
879 
880  case AUTH_REQ_KRB5:
882  libpq_gettext("Kerberos 5 authentication not supported\n"));
883  return STATUS_ERROR;
884 
885 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
886  case AUTH_REQ_GSS:
887 #if !defined(ENABLE_SSPI)
888  /* no native SSPI, so use GSSAPI library for it */
889  case AUTH_REQ_SSPI:
890 #endif
891  {
892  int r;
893 
894  pglock_thread();
895 
896  /*
897  * If we have both GSS and SSPI support compiled in, use SSPI
898  * support by default. This is overridable by a connection
899  * string parameter. Note that when using SSPI we still leave
900  * the negotiate parameter off, since we want SSPI to use the
901  * GSSAPI kerberos protocol. For actual SSPI negotiate
902  * protocol, we use AUTH_REQ_SSPI.
903  */
904 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
905  if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
906  r = pg_GSS_startup(conn, payloadlen);
907  else
908  r = pg_SSPI_startup(conn, 0, payloadlen);
909 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
910  r = pg_GSS_startup(conn, payloadlen);
911 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
912  r = pg_SSPI_startup(conn, 0, payloadlen);
913 #endif
914  if (r != STATUS_OK)
915  {
916  /* Error message already filled in. */
917  pgunlock_thread();
918  return STATUS_ERROR;
919  }
920  pgunlock_thread();
921  }
922  break;
923 
924  case AUTH_REQ_GSS_CONT:
925  {
926  int r;
927 
928  pglock_thread();
929 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
930  if (conn->usesspi)
931  r = pg_SSPI_continue(conn, payloadlen);
932  else
933  r = pg_GSS_continue(conn, payloadlen);
934 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
935  r = pg_GSS_continue(conn, payloadlen);
936 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
937  r = pg_SSPI_continue(conn, payloadlen);
938 #endif
939  if (r != STATUS_OK)
940  {
941  /* Error message already filled in. */
942  pgunlock_thread();
943  return STATUS_ERROR;
944  }
945  pgunlock_thread();
946  }
947  break;
948 #else /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
949  /* No GSSAPI *or* SSPI support */
950  case AUTH_REQ_GSS:
951  case AUTH_REQ_GSS_CONT:
953  libpq_gettext("GSSAPI authentication not supported\n"));
954  return STATUS_ERROR;
955 #endif /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
956 
957 #ifdef ENABLE_SSPI
958  case AUTH_REQ_SSPI:
959 
960  /*
961  * SSPI has its own startup message so libpq can decide which
962  * method to use. Indicate to pg_SSPI_startup that we want SSPI
963  * negotiation instead of Kerberos.
964  */
965  pglock_thread();
966  if (pg_SSPI_startup(conn, 1, payloadlen) != STATUS_OK)
967  {
968  /* Error message already filled in. */
969  pgunlock_thread();
970  return STATUS_ERROR;
971  }
972  pgunlock_thread();
973  break;
974 #else
975 
976  /*
977  * No SSPI support. However, if we have GSSAPI but not SSPI
978  * support, AUTH_REQ_SSPI will have been handled in the codepath
979  * for AUTH_REQ_GSS above, so don't duplicate the case label in
980  * that case.
981  */
982 #if !defined(ENABLE_GSS)
983  case AUTH_REQ_SSPI:
985  libpq_gettext("SSPI authentication not supported\n"));
986  return STATUS_ERROR;
987 #endif /* !define(ENABLE_GSS) */
988 #endif /* ENABLE_SSPI */
989 
990 
991  case AUTH_REQ_CRYPT:
993  libpq_gettext("Crypt authentication not supported\n"));
994  return STATUS_ERROR;
995 
996  case AUTH_REQ_MD5:
997  case AUTH_REQ_PASSWORD:
998  {
999  char *password;
1000 
1001  conn->password_needed = true;
1002  password = conn->connhost[conn->whichhost].password;
1003  if (password == NULL)
1004  password = conn->pgpass;
1005  if (password == NULL || password[0] == '\0')
1006  {
1009  return STATUS_ERROR;
1010  }
1011  if (pg_password_sendauth(conn, password, areq) != STATUS_OK)
1012  {
1014  "fe_sendauth: error sending password authentication\n");
1015  return STATUS_ERROR;
1016  }
1017  break;
1018  }
1019 
1020  case AUTH_REQ_SASL:
1021 
1022  /*
1023  * The request contains the name (as assigned by IANA) of the
1024  * authentication mechanism.
1025  */
1026  if (pg_SASL_init(conn, payloadlen) != STATUS_OK)
1027  {
1028  /* pg_SASL_init already set the error message */
1029  return STATUS_ERROR;
1030  }
1031  break;
1032 
1033  case AUTH_REQ_SASL_CONT:
1034  case AUTH_REQ_SASL_FIN:
1035  if (conn->sasl_state == NULL)
1036  {
1038  "fe_sendauth: invalid authentication request from server: AUTH_REQ_SASL_CONT without AUTH_REQ_SASL\n");
1039  return STATUS_ERROR;
1040  }
1041  oldmsglen = conn->errorMessage.len;
1042  if (pg_SASL_continue(conn, payloadlen,
1043  (areq == AUTH_REQ_SASL_FIN)) != STATUS_OK)
1044  {
1045  /* Use this message if pg_SASL_continue didn't supply one */
1046  if (conn->errorMessage.len == oldmsglen)
1048  "fe_sendauth: error in SASL authentication\n");
1049  return STATUS_ERROR;
1050  }
1051  break;
1052 
1053  case AUTH_REQ_SCM_CREDS:
1054  if (pg_local_sendauth(conn) != STATUS_OK)
1055  return STATUS_ERROR;
1056  break;
1057 
1058  default:
1060  libpq_gettext("authentication method %u not supported\n"), areq);
1061  return STATUS_ERROR;
1062  }
1063 
1064  return STATUS_OK;
1065 }
1066 
1067 
1068 /*
1069  * pg_fe_getauthname
1070  *
1071  * Returns a pointer to malloc'd space containing whatever name the user
1072  * has authenticated to the system. If there is an error, return NULL,
1073  * and append a suitable error message to *errorMessage if that's not NULL.
1074  */
1075 char *
1077 {
1078  char *result = NULL;
1079  const char *name = NULL;
1080 
1081 #ifdef WIN32
1082  /* Microsoft recommends buffer size of UNLEN+1, where UNLEN = 256 */
1083  char username[256 + 1];
1084  DWORD namesize = sizeof(username);
1085 #else
1086  uid_t user_id = geteuid();
1087  char pwdbuf[BUFSIZ];
1088  struct passwd pwdstr;
1089  struct passwd *pw = NULL;
1090  int pwerr;
1091 #endif
1092 
1093  /*
1094  * Some users are using configure --enable-thread-safety-force, so we
1095  * might as well do the locking within our library to protect
1096  * pqGetpwuid(). In fact, application developers can use getpwuid() in
1097  * their application if they use the locking call we provide, or install
1098  * their own locking function using PQregisterThreadLock().
1099  */
1100  pglock_thread();
1101 
1102 #ifdef WIN32
1103  if (GetUserName(username, &namesize))
1104  name = username;
1105  else if (errorMessage)
1106  appendPQExpBuffer(errorMessage,
1107  libpq_gettext("user name lookup failure: error code %lu\n"),
1108  GetLastError());
1109 #else
1110  pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw);
1111  if (pw != NULL)
1112  name = pw->pw_name;
1113  else if (errorMessage)
1114  {
1115  if (pwerr != 0)
1116  appendPQExpBuffer(errorMessage,
1117  libpq_gettext("could not look up local user ID %d: %s\n"),
1118  (int) user_id,
1119  strerror_r(pwerr, pwdbuf, sizeof(pwdbuf)));
1120  else
1121  appendPQExpBuffer(errorMessage,
1122  libpq_gettext("local user with ID %d does not exist\n"),
1123  (int) user_id);
1124  }
1125 #endif
1126 
1127  if (name)
1128  {
1129  result = strdup(name);
1130  if (result == NULL && errorMessage)
1131  appendPQExpBufferStr(errorMessage,
1132  libpq_gettext("out of memory\n"));
1133  }
1134 
1135  pgunlock_thread();
1136 
1137  return result;
1138 }
1139 
1140 
1141 /*
1142  * PQencryptPassword -- exported routine to encrypt a password with MD5
1143  *
1144  * This function is equivalent to calling PQencryptPasswordConn with
1145  * "md5" as the encryption method, except that this doesn't require
1146  * a connection object. This function is deprecated, use
1147  * PQencryptPasswordConn instead.
1148  */
1149 char *
1150 PQencryptPassword(const char *passwd, const char *user)
1151 {
1152  char *crypt_pwd;
1153 
1154  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1155  if (!crypt_pwd)
1156  return NULL;
1157 
1158  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1159  {
1160  free(crypt_pwd);
1161  return NULL;
1162  }
1163 
1164  return crypt_pwd;
1165 }
1166 
1167 /*
1168  * PQencryptPasswordConn -- exported routine to encrypt a password
1169  *
1170  * This is intended to be used by client applications that wish to send
1171  * commands like ALTER USER joe PASSWORD 'pwd'. The password need not
1172  * be sent in cleartext if it is encrypted on the client side. This is
1173  * good because it ensures the cleartext password won't end up in logs,
1174  * pg_stat displays, etc. We export the function so that clients won't
1175  * be dependent on low-level details like whether the encryption is MD5
1176  * or something else.
1177  *
1178  * Arguments are a connection object, the cleartext password, the SQL
1179  * name of the user it is for, and a string indicating the algorithm to
1180  * use for encrypting the password. If algorithm is NULL, this queries
1181  * the server for the current 'password_encryption' value. If you wish
1182  * to avoid that, e.g. to avoid blocking, you can execute
1183  * 'show password_encryption' yourself before calling this function, and
1184  * pass it as the algorithm.
1185  *
1186  * Return value is a malloc'd string. The client may assume the string
1187  * doesn't contain any special characters that would require escaping.
1188  * On error, an error message is stored in the connection object, and
1189  * returns NULL.
1190  */
1191 char *
1192 PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user,
1193  const char *algorithm)
1194 {
1195 #define MAX_ALGORITHM_NAME_LEN 50
1196  char algobuf[MAX_ALGORITHM_NAME_LEN + 1];
1197  char *crypt_pwd = NULL;
1198 
1199  if (!conn)
1200  return NULL;
1201 
1203 
1204  /* If no algorithm was given, ask the server. */
1205  if (algorithm == NULL)
1206  {
1207  PGresult *res;
1208  char *val;
1209 
1210  res = PQexec(conn, "show password_encryption");
1211  if (res == NULL)
1212  {
1213  /* PQexec() should've set conn->errorMessage already */
1214  return NULL;
1215  }
1216  if (PQresultStatus(res) != PGRES_TUPLES_OK)
1217  {
1218  /* PQexec() should've set conn->errorMessage already */
1219  PQclear(res);
1220  return NULL;
1221  }
1222  if (PQntuples(res) != 1 || PQnfields(res) != 1)
1223  {
1224  PQclear(res);
1226  libpq_gettext("unexpected shape of result set returned for SHOW\n"));
1227  return NULL;
1228  }
1229  val = PQgetvalue(res, 0, 0);
1230 
1231  if (strlen(val) > MAX_ALGORITHM_NAME_LEN)
1232  {
1233  PQclear(res);
1235  libpq_gettext("password_encryption value too long\n"));
1236  return NULL;
1237  }
1238  strcpy(algobuf, val);
1239  PQclear(res);
1240 
1241  algorithm = algobuf;
1242  }
1243 
1244  /*
1245  * Also accept "on" and "off" as aliases for "md5", because
1246  * password_encryption was a boolean before PostgreSQL 10. We refuse to
1247  * send the password in plaintext even if it was "off".
1248  */
1249  if (strcmp(algorithm, "on") == 0 ||
1250  strcmp(algorithm, "off") == 0)
1251  algorithm = "md5";
1252 
1253  /*
1254  * Ok, now we know what algorithm to use
1255  */
1256  if (strcmp(algorithm, "scram-sha-256") == 0)
1257  {
1258  crypt_pwd = pg_fe_scram_build_secret(passwd);
1259  }
1260  else if (strcmp(algorithm, "md5") == 0)
1261  {
1262  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1263  if (crypt_pwd)
1264  {
1265  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1266  {
1267  free(crypt_pwd);
1268  crypt_pwd = NULL;
1269  }
1270  }
1271  }
1272  else
1273  {
1275  libpq_gettext("unrecognized password encryption algorithm \"%s\"\n"),
1276  algorithm);
1277  return NULL;
1278  }
1279 
1280  if (!crypt_pwd)
1282  libpq_gettext("out of memory\n"));
1283 
1284  return crypt_pwd;
1285 }
int pqFlush(PGconn *conn)
Definition: fe-misc.c:965
size_t iov_len
Definition: pg_iovec.h:27
int PQnfields(const PGresult *res)
Definition: fe-exec.c:3175
#define AUTH_REQ_SSPI
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#define AUTH_REQ_SASL_FIN
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ExecStatusType PQresultStatus(const PGresult *res)
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#define AUTH_REQ_SASL_CONT
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int pqPutMsgStart(char msg_type, PGconn *conn)
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#define AUTH_REQ_SASL
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