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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 "libpq-fe.h"
44 #include "fe-auth.h"
45 
46 
47 #ifdef ENABLE_GSS
48 /*
49  * GSSAPI authentication system.
50  */
51 
52 #include "fe-gssapi-common.h"
53 
54 /*
55  * Continue GSS authentication with next token as needed.
56  */
57 static int
58 pg_GSS_continue(PGconn *conn, int payloadlen)
59 {
60  OM_uint32 maj_stat,
61  min_stat,
62  lmin_s;
63  gss_buffer_desc ginbuf;
64  gss_buffer_desc goutbuf;
65 
66  /*
67  * On first call, there's no input token. On subsequent calls, read the
68  * input token into a GSS buffer.
69  */
70  if (conn->gctx != GSS_C_NO_CONTEXT)
71  {
72  ginbuf.length = payloadlen;
73  ginbuf.value = malloc(payloadlen);
74  if (!ginbuf.value)
75  {
77  libpq_gettext("out of memory allocating GSSAPI buffer (%d)\n"),
78  payloadlen);
79  return STATUS_ERROR;
80  }
81  if (pqGetnchar(ginbuf.value, payloadlen, conn))
82  {
83  /*
84  * Shouldn't happen, because the caller should've ensured that the
85  * whole message is already in the input buffer.
86  */
87  free(ginbuf.value);
88  return STATUS_ERROR;
89  }
90  }
91  else
92  {
93  ginbuf.length = 0;
94  ginbuf.value = NULL;
95  }
96 
97  maj_stat = gss_init_sec_context(&min_stat,
98  GSS_C_NO_CREDENTIAL,
99  &conn->gctx,
100  conn->gtarg_nam,
101  GSS_C_NO_OID,
102  GSS_C_MUTUAL_FLAG,
103  0,
104  GSS_C_NO_CHANNEL_BINDINGS,
105  (ginbuf.value == NULL) ? GSS_C_NO_BUFFER : &ginbuf,
106  NULL,
107  &goutbuf,
108  NULL,
109  NULL);
110 
111  if (ginbuf.value)
112  free(ginbuf.value);
113 
114  if (goutbuf.length != 0)
115  {
116  /*
117  * GSS generated data to send to the server. We don't care if it's the
118  * first or subsequent packet, just send the same kind of password
119  * packet.
120  */
121  if (pqPacketSend(conn, 'p',
122  goutbuf.value, goutbuf.length) != STATUS_OK)
123  {
124  gss_release_buffer(&lmin_s, &goutbuf);
125  return STATUS_ERROR;
126  }
127  }
128  gss_release_buffer(&lmin_s, &goutbuf);
129 
130  if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
131  {
132  pg_GSS_error(libpq_gettext("GSSAPI continuation error"),
133  conn,
134  maj_stat, min_stat);
135  gss_release_name(&lmin_s, &conn->gtarg_nam);
136  if (conn->gctx)
137  gss_delete_sec_context(&lmin_s, &conn->gctx, GSS_C_NO_BUFFER);
138  return STATUS_ERROR;
139  }
140 
141  if (maj_stat == GSS_S_COMPLETE)
142  gss_release_name(&lmin_s, &conn->gtarg_nam);
143 
144  return STATUS_OK;
145 }
146 
147 /*
148  * Send initial GSS authentication token
149  */
150 static int
151 pg_GSS_startup(PGconn *conn, int payloadlen)
152 {
153  int ret;
154  char *host = conn->connhost[conn->whichhost].host;
155 
156  if (!(host && host[0] != '\0'))
157  {
159  libpq_gettext("host name must be specified\n"));
160  return STATUS_ERROR;
161  }
162 
163  if (conn->gctx)
164  {
166  libpq_gettext("duplicate GSS authentication request\n"));
167  return STATUS_ERROR;
168  }
169 
170  ret = pg_GSS_load_servicename(conn);
171  if (ret != STATUS_OK)
172  return ret;
173 
174  /*
175  * Initial packet is the same as a continuation packet with no initial
176  * context.
177  */
178  conn->gctx = GSS_C_NO_CONTEXT;
179 
180  return pg_GSS_continue(conn, payloadlen);
181 }
182 #endif /* ENABLE_GSS */
183 
184 
185 #ifdef ENABLE_SSPI
186 /*
187  * SSPI authentication system (Windows only)
188  */
189 
190 static void
191 pg_SSPI_error(PGconn *conn, const char *mprefix, SECURITY_STATUS r)
192 {
193  char sysmsg[256];
194 
195  if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
196  FORMAT_MESSAGE_FROM_SYSTEM,
197  NULL, r, 0,
198  sysmsg, sizeof(sysmsg), NULL) == 0)
199  printfPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x\n",
200  mprefix, (unsigned int) r);
201  else
202  printfPQExpBuffer(&conn->errorMessage, "%s: %s (%x)\n",
203  mprefix, sysmsg, (unsigned int) r);
204 }
205 
206 /*
207  * Continue SSPI authentication with next token as needed.
208  */
209 static int
210 pg_SSPI_continue(PGconn *conn, int payloadlen)
211 {
212  SECURITY_STATUS r;
213  CtxtHandle newContext;
214  ULONG contextAttr;
215  SecBufferDesc inbuf;
216  SecBufferDesc outbuf;
217  SecBuffer OutBuffers[1];
218  SecBuffer InBuffers[1];
219  char *inputbuf = NULL;
220 
221  if (conn->sspictx != NULL)
222  {
223  /*
224  * On runs other than the first we have some data to send. Put this
225  * data in a SecBuffer type structure.
226  */
227  inputbuf = malloc(payloadlen);
228  if (!inputbuf)
229  {
231  libpq_gettext("out of memory allocating SSPI buffer (%d)\n"),
232  payloadlen);
233  return STATUS_ERROR;
234  }
235  if (pqGetnchar(inputbuf, payloadlen, conn))
236  {
237  /*
238  * Shouldn't happen, because the caller should've ensured that the
239  * whole message is already in the input buffer.
240  */
241  free(inputbuf);
242  return STATUS_ERROR;
243  }
244 
245  inbuf.ulVersion = SECBUFFER_VERSION;
246  inbuf.cBuffers = 1;
247  inbuf.pBuffers = InBuffers;
248  InBuffers[0].pvBuffer = inputbuf;
249  InBuffers[0].cbBuffer = payloadlen;
250  InBuffers[0].BufferType = SECBUFFER_TOKEN;
251  }
252 
253  OutBuffers[0].pvBuffer = NULL;
254  OutBuffers[0].BufferType = SECBUFFER_TOKEN;
255  OutBuffers[0].cbBuffer = 0;
256  outbuf.cBuffers = 1;
257  outbuf.pBuffers = OutBuffers;
258  outbuf.ulVersion = SECBUFFER_VERSION;
259 
260  r = InitializeSecurityContext(conn->sspicred,
261  conn->sspictx,
262  conn->sspitarget,
263  ISC_REQ_ALLOCATE_MEMORY,
264  0,
265  SECURITY_NETWORK_DREP,
266  (conn->sspictx == NULL) ? NULL : &inbuf,
267  0,
268  &newContext,
269  &outbuf,
270  &contextAttr,
271  NULL);
272 
273  /* we don't need the input anymore */
274  if (inputbuf)
275  free(inputbuf);
276 
277  if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED)
278  {
279  pg_SSPI_error(conn, libpq_gettext("SSPI continuation error"), r);
280 
281  return STATUS_ERROR;
282  }
283 
284  if (conn->sspictx == NULL)
285  {
286  /* On first run, transfer retrieved context handle */
287  conn->sspictx = malloc(sizeof(CtxtHandle));
288  if (conn->sspictx == NULL)
289  {
290  printfPQExpBuffer(&conn->errorMessage, 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  */
309  printfPQExpBuffer(&conn->errorMessage, "SSPI returned invalid number of output buffers\n");
310  return STATUS_ERROR;
311  }
312 
313  /*
314  * If the negotiation is complete, there may be zero bytes to send.
315  * The server is at this point not expecting any more data, so don't
316  * send it.
317  */
318  if (outbuf.pBuffers[0].cbBuffer > 0)
319  {
320  if (pqPacketSend(conn, 'p',
321  outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer))
322  {
323  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
324  return STATUS_ERROR;
325  }
326  }
327  FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
328  }
329 
330  /* Cleanup is handled by the code in freePGconn() */
331  return STATUS_OK;
332 }
333 
334 /*
335  * Send initial SSPI authentication token.
336  * If use_negotiate is 0, use kerberos authentication package which is
337  * compatible with Unix. If use_negotiate is 1, use the negotiate package
338  * which supports both kerberos and NTLM, but is not compatible with Unix.
339  */
340 static int
341 pg_SSPI_startup(PGconn *conn, int use_negotiate, int payloadlen)
342 {
343  SECURITY_STATUS r;
344  TimeStamp expire;
345  char *host = conn->connhost[conn->whichhost].host;
346 
347  if (conn->sspictx)
348  {
350  libpq_gettext("duplicate SSPI authentication request\n"));
351  return STATUS_ERROR;
352  }
353 
354  /*
355  * Retrieve credentials handle
356  */
357  conn->sspicred = malloc(sizeof(CredHandle));
358  if (conn->sspicred == NULL)
359  {
360  printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
361  return STATUS_ERROR;
362  }
363 
364  r = AcquireCredentialsHandle(NULL,
365  use_negotiate ? "negotiate" : "kerberos",
366  SECPKG_CRED_OUTBOUND,
367  NULL,
368  NULL,
369  NULL,
370  NULL,
371  conn->sspicred,
372  &expire);
373  if (r != SEC_E_OK)
374  {
375  pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r);
376  free(conn->sspicred);
377  conn->sspicred = NULL;
378  return STATUS_ERROR;
379  }
380 
381  /*
382  * Compute target principal name. SSPI has a different format from GSSAPI,
383  * but not more complex. We can skip the @REALM part, because Windows will
384  * fill that in for us automatically.
385  */
386  if (!(host && host[0] != '\0'))
387  {
389  libpq_gettext("host name must be specified\n"));
390  return STATUS_ERROR;
391  }
392  conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2);
393  if (!conn->sspitarget)
394  {
395  printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
396  return STATUS_ERROR;
397  }
398  sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, host);
399 
400  /*
401  * Indicate that we're in SSPI authentication mode to make sure that
402  * pg_SSPI_continue is called next time in the negotiation.
403  */
404  conn->usesspi = 1;
405 
406  return pg_SSPI_continue(conn, payloadlen);
407 }
408 #endif /* ENABLE_SSPI */
409 
410 /*
411  * Initialize SASL authentication exchange.
412  */
413 static int
414 pg_SASL_init(PGconn *conn, int payloadlen)
415 {
416  char *initialresponse = NULL;
417  int initialresponselen;
418  bool done;
419  bool success;
420  const char *selected_mechanism;
421  PQExpBufferData mechanism_buf;
422  char *password;
423 
424  initPQExpBuffer(&mechanism_buf);
425 
426  if (conn->sasl_state)
427  {
429  libpq_gettext("duplicate SASL authentication request\n"));
430  goto error;
431  }
432 
433  /*
434  * Parse the list of SASL authentication mechanisms in the
435  * AuthenticationSASL message, and select the best mechanism that we
436  * support. SCRAM-SHA-256-PLUS and SCRAM-SHA-256 are the only ones
437  * supported at the moment, listed by order of decreasing importance.
438  */
439  selected_mechanism = NULL;
440  for (;;)
441  {
442  if (pqGets(&mechanism_buf, conn))
443  {
445  "fe_sendauth: invalid authentication request from server: invalid list of authentication mechanisms\n");
446  goto error;
447  }
448  if (PQExpBufferDataBroken(mechanism_buf))
449  goto oom_error;
450 
451  /* An empty string indicates end of list */
452  if (mechanism_buf.data[0] == '\0')
453  break;
454 
455  /*
456  * Select the mechanism to use. Pick SCRAM-SHA-256-PLUS over anything
457  * else if a channel binding type is set and if the client supports
458  * it. Pick SCRAM-SHA-256 if nothing else has already been picked. If
459  * we add more mechanisms, a more refined priority mechanism might
460  * become necessary.
461  */
462  if (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0)
463  {
464  if (conn->ssl_in_use)
465  {
466  /*
467  * The server has offered SCRAM-SHA-256-PLUS, which is only
468  * supported by the client if a hash of the peer certificate
469  * can be created.
470  */
471 #ifdef HAVE_PGTLS_GET_PEER_CERTIFICATE_HASH
472  selected_mechanism = SCRAM_SHA_256_PLUS_NAME;
473 #endif
474  }
475  else
476  {
477  /*
478  * The server offered SCRAM-SHA-256-PLUS, but the connection
479  * is not SSL-encrypted. That's not sane. Perhaps SSL was
480  * stripped by a proxy? There's no point in continuing,
481  * because the server will reject the connection anyway if we
482  * try authenticate without channel binding even though both
483  * the client and server supported it. The SCRAM exchange
484  * checks for that, to prevent downgrade attacks.
485  */
487  libpq_gettext("server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection\n"));
488  goto error;
489  }
490  }
491  else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 &&
492  !selected_mechanism)
493  selected_mechanism = SCRAM_SHA_256_NAME;
494  }
495 
496  if (!selected_mechanism)
497  {
499  libpq_gettext("none of the server's SASL authentication mechanisms are supported\n"));
500  goto error;
501  }
502 
503  /*
504  * Now that the SASL mechanism has been chosen for the exchange,
505  * initialize its state information.
506  */
507 
508  /*
509  * First, select the password to use for the exchange, complaining if
510  * there isn't one. Currently, all supported SASL mechanisms require a
511  * password, so we can just go ahead here without further distinction.
512  */
513  conn->password_needed = true;
514  password = conn->connhost[conn->whichhost].password;
515  if (password == NULL)
516  password = conn->pgpass;
517  if (password == NULL || password[0] == '\0')
518  {
521  goto error;
522  }
523 
524  /*
525  * Initialize the SASL state information with all the information gathered
526  * during the initial exchange.
527  *
528  * Note: Only tls-unique is supported for the moment.
529  */
530  conn->sasl_state = pg_fe_scram_init(conn,
531  password,
532  selected_mechanism);
533  if (!conn->sasl_state)
534  goto oom_error;
535 
536  /* Get the mechanism-specific Initial Client Response, if any */
538  NULL, -1,
539  &initialresponse, &initialresponselen,
540  &done, &success);
541 
542  if (done && !success)
543  goto error;
544 
545  /*
546  * Build a SASLInitialResponse message, and send it.
547  */
548  if (pqPutMsgStart('p', true, conn))
549  goto error;
550  if (pqPuts(selected_mechanism, conn))
551  goto error;
552  if (initialresponse)
553  {
554  if (pqPutInt(initialresponselen, 4, conn))
555  goto error;
556  if (pqPutnchar(initialresponse, initialresponselen, conn))
557  goto error;
558  }
559  if (pqPutMsgEnd(conn))
560  goto error;
561  if (pqFlush(conn))
562  goto error;
563 
564  termPQExpBuffer(&mechanism_buf);
565  if (initialresponse)
566  free(initialresponse);
567 
568  return STATUS_OK;
569 
570 error:
571  termPQExpBuffer(&mechanism_buf);
572  if (initialresponse)
573  free(initialresponse);
574  return STATUS_ERROR;
575 
576 oom_error:
577  termPQExpBuffer(&mechanism_buf);
578  if (initialresponse)
579  free(initialresponse);
581  libpq_gettext("out of memory\n"));
582  return STATUS_ERROR;
583 }
584 
585 /*
586  * Exchange a message for SASL communication protocol with the backend.
587  * This should be used after calling pg_SASL_init to set up the status of
588  * the protocol.
589  */
590 static int
591 pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
592 {
593  char *output;
594  int outputlen;
595  bool done;
596  bool success;
597  int res;
598  char *challenge;
599 
600  /* Read the SASL challenge from the AuthenticationSASLContinue message. */
601  challenge = malloc(payloadlen + 1);
602  if (!challenge)
603  {
605  libpq_gettext("out of memory allocating SASL buffer (%d)\n"),
606  payloadlen);
607  return STATUS_ERROR;
608  }
609 
610  if (pqGetnchar(challenge, payloadlen, conn))
611  {
612  free(challenge);
613  return STATUS_ERROR;
614  }
615  /* For safety and convenience, ensure the buffer is NULL-terminated. */
616  challenge[payloadlen] = '\0';
617 
619  challenge, payloadlen,
620  &output, &outputlen,
621  &done, &success);
622  free(challenge); /* don't need the input anymore */
623 
624  if (final && !done)
625  {
626  if (outputlen != 0)
627  free(output);
628 
630  libpq_gettext("AuthenticationSASLFinal received from server, but SASL authentication was not completed\n"));
631  return STATUS_ERROR;
632  }
633  if (outputlen != 0)
634  {
635  /*
636  * Send the SASL response to the server.
637  */
638  res = pqPacketSend(conn, 'p', output, outputlen);
639  free(output);
640 
641  if (res != STATUS_OK)
642  return STATUS_ERROR;
643  }
644 
645  if (done && !success)
646  return STATUS_ERROR;
647 
648  return STATUS_OK;
649 }
650 
651 /*
652  * Respond to AUTH_REQ_SCM_CREDS challenge.
653  *
654  * Note: this is dead code as of Postgres 9.1, because current backends will
655  * never send this challenge. But we must keep it as long as libpq needs to
656  * interoperate with pre-9.1 servers. It is believed to be needed only on
657  * Debian/kFreeBSD (ie, FreeBSD kernel with Linux userland, so that the
658  * getpeereid() function isn't provided by libc).
659  */
660 static int
662 {
663 #ifdef HAVE_STRUCT_CMSGCRED
664  char buf;
665  struct iovec iov;
666  struct msghdr msg;
667  struct cmsghdr *cmsg;
668  union
669  {
670  struct cmsghdr hdr;
671  unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))];
672  } cmsgbuf;
673 
674  /*
675  * The backend doesn't care what we send here, but it wants exactly one
676  * character to force recvmsg() to block and wait for us.
677  */
678  buf = '\0';
679  iov.iov_base = &buf;
680  iov.iov_len = 1;
681 
682  memset(&msg, 0, sizeof(msg));
683  msg.msg_iov = &iov;
684  msg.msg_iovlen = 1;
685 
686  /* We must set up a message that will be filled in by kernel */
687  memset(&cmsgbuf, 0, sizeof(cmsgbuf));
688  msg.msg_control = &cmsgbuf.buf;
689  msg.msg_controllen = sizeof(cmsgbuf.buf);
690  cmsg = CMSG_FIRSTHDR(&msg);
691  cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
692  cmsg->cmsg_level = SOL_SOCKET;
693  cmsg->cmsg_type = SCM_CREDS;
694 
695  if (sendmsg(conn->sock, &msg, 0) == -1)
696  {
697  char sebuf[PG_STRERROR_R_BUFLEN];
698 
700  "pg_local_sendauth: sendmsg: %s\n",
701  strerror_r(errno, sebuf, sizeof(sebuf)));
702  return STATUS_ERROR;
703  }
704  return STATUS_OK;
705 #else
707  libpq_gettext("SCM_CRED authentication method not supported\n"));
708  return STATUS_ERROR;
709 #endif
710 }
711 
712 static int
714 {
715  int ret;
716  char *crypt_pwd = NULL;
717  const char *pwd_to_send;
718  char md5Salt[4];
719 
720  /* Read the salt from the AuthenticationMD5Password message. */
721  if (areq == AUTH_REQ_MD5)
722  {
723  if (pqGetnchar(md5Salt, 4, conn))
724  return STATUS_ERROR; /* shouldn't happen */
725  }
726 
727  /* Encrypt the password if needed. */
728 
729  switch (areq)
730  {
731  case AUTH_REQ_MD5:
732  {
733  char *crypt_pwd2;
734 
735  /* Allocate enough space for two MD5 hashes */
736  crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
737  if (!crypt_pwd)
738  {
740  libpq_gettext("out of memory\n"));
741  return STATUS_ERROR;
742  }
743 
744  crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
745  if (!pg_md5_encrypt(password, conn->pguser,
746  strlen(conn->pguser), crypt_pwd2))
747  {
748  free(crypt_pwd);
749  return STATUS_ERROR;
750  }
751  if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt,
752  4, crypt_pwd))
753  {
754  free(crypt_pwd);
755  return STATUS_ERROR;
756  }
757 
758  pwd_to_send = crypt_pwd;
759  break;
760  }
761  case AUTH_REQ_PASSWORD:
762  pwd_to_send = password;
763  break;
764  default:
765  return STATUS_ERROR;
766  }
767  /* Packet has a message type as of protocol 3.0 */
768  if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
769  ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
770  else
771  ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
772  if (crypt_pwd)
773  free(crypt_pwd);
774  return ret;
775 }
776 
777 /*
778  * pg_fe_sendauth
779  * client demux routine for processing an authentication request
780  *
781  * The server has sent us an authentication challenge (or OK). Send an
782  * appropriate response. The caller has ensured that the whole message is
783  * now in the input buffer, and has already read the type and length of
784  * it. We are responsible for reading any remaining extra data, specific
785  * to the authentication method. 'payloadlen' is the remaining length in
786  * the message.
787  */
788 int
789 pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
790 {
791  switch (areq)
792  {
793  case AUTH_REQ_OK:
794  break;
795 
796  case AUTH_REQ_KRB4:
798  libpq_gettext("Kerberos 4 authentication not supported\n"));
799  return STATUS_ERROR;
800 
801  case AUTH_REQ_KRB5:
803  libpq_gettext("Kerberos 5 authentication not supported\n"));
804  return STATUS_ERROR;
805 
806 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
807  case AUTH_REQ_GSS:
808 #if !defined(ENABLE_SSPI)
809  /* no native SSPI, so use GSSAPI library for it */
810  case AUTH_REQ_SSPI:
811 #endif
812  {
813  int r;
814 
815  pglock_thread();
816 
817  /*
818  * If we have both GSS and SSPI support compiled in, use SSPI
819  * support by default. This is overridable by a connection
820  * string parameter. Note that when using SSPI we still leave
821  * the negotiate parameter off, since we want SSPI to use the
822  * GSSAPI kerberos protocol. For actual SSPI negotiate
823  * protocol, we use AUTH_REQ_SSPI.
824  */
825 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
826  if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
827  r = pg_GSS_startup(conn, payloadlen);
828  else
829  r = pg_SSPI_startup(conn, 0, payloadlen);
830 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
831  r = pg_GSS_startup(conn, payloadlen);
832 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
833  r = pg_SSPI_startup(conn, 0, payloadlen);
834 #endif
835  if (r != STATUS_OK)
836  {
837  /* Error message already filled in. */
838  pgunlock_thread();
839  return STATUS_ERROR;
840  }
841  pgunlock_thread();
842  }
843  break;
844 
845  case AUTH_REQ_GSS_CONT:
846  {
847  int r;
848 
849  pglock_thread();
850 #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
851  if (conn->usesspi)
852  r = pg_SSPI_continue(conn, payloadlen);
853  else
854  r = pg_GSS_continue(conn, payloadlen);
855 #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
856  r = pg_GSS_continue(conn, payloadlen);
857 #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
858  r = pg_SSPI_continue(conn, payloadlen);
859 #endif
860  if (r != STATUS_OK)
861  {
862  /* Error message already filled in. */
863  pgunlock_thread();
864  return STATUS_ERROR;
865  }
866  pgunlock_thread();
867  }
868  break;
869 #else /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
870  /* No GSSAPI *or* SSPI support */
871  case AUTH_REQ_GSS:
872  case AUTH_REQ_GSS_CONT:
874  libpq_gettext("GSSAPI authentication not supported\n"));
875  return STATUS_ERROR;
876 #endif /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
877 
878 #ifdef ENABLE_SSPI
879  case AUTH_REQ_SSPI:
880 
881  /*
882  * SSPI has its own startup message so libpq can decide which
883  * method to use. Indicate to pg_SSPI_startup that we want SSPI
884  * negotiation instead of Kerberos.
885  */
886  pglock_thread();
887  if (pg_SSPI_startup(conn, 1, payloadlen) != STATUS_OK)
888  {
889  /* Error message already filled in. */
890  pgunlock_thread();
891  return STATUS_ERROR;
892  }
893  pgunlock_thread();
894  break;
895 #else
896 
897  /*
898  * No SSPI support. However, if we have GSSAPI but not SSPI
899  * support, AUTH_REQ_SSPI will have been handled in the codepath
900  * for AUTH_REQ_GSS above, so don't duplicate the case label in
901  * that case.
902  */
903 #if !defined(ENABLE_GSS)
904  case AUTH_REQ_SSPI:
906  libpq_gettext("SSPI authentication not supported\n"));
907  return STATUS_ERROR;
908 #endif /* !define(ENABLE_GSS) */
909 #endif /* ENABLE_SSPI */
910 
911 
912  case AUTH_REQ_CRYPT:
914  libpq_gettext("Crypt authentication not supported\n"));
915  return STATUS_ERROR;
916 
917  case AUTH_REQ_MD5:
918  case AUTH_REQ_PASSWORD:
919  {
920  char *password;
921 
922  conn->password_needed = true;
923  password = conn->connhost[conn->whichhost].password;
924  if (password == NULL)
925  password = conn->pgpass;
926  if (password == NULL || password[0] == '\0')
927  {
930  return STATUS_ERROR;
931  }
932  if (pg_password_sendauth(conn, password, areq) != STATUS_OK)
933  {
935  "fe_sendauth: error sending password authentication\n");
936  return STATUS_ERROR;
937  }
938  break;
939  }
940 
941  case AUTH_REQ_SASL:
942 
943  /*
944  * The request contains the name (as assigned by IANA) of the
945  * authentication mechanism.
946  */
947  if (pg_SASL_init(conn, payloadlen) != STATUS_OK)
948  {
949  /* pg_SASL_init already set the error message */
950  return STATUS_ERROR;
951  }
952  break;
953 
954  case AUTH_REQ_SASL_CONT:
955  case AUTH_REQ_SASL_FIN:
956  if (conn->sasl_state == NULL)
957  {
959  "fe_sendauth: invalid authentication request from server: AUTH_REQ_SASL_CONT without AUTH_REQ_SASL\n");
960  return STATUS_ERROR;
961  }
962  if (pg_SASL_continue(conn, payloadlen,
963  (areq == AUTH_REQ_SASL_FIN)) != STATUS_OK)
964  {
965  /* Use error message, if set already */
966  if (conn->errorMessage.len == 0)
968  "fe_sendauth: error in SASL authentication\n");
969  return STATUS_ERROR;
970  }
971  break;
972 
973  case AUTH_REQ_SCM_CREDS:
974  if (pg_local_sendauth(conn) != STATUS_OK)
975  return STATUS_ERROR;
976  break;
977 
978  default:
980  libpq_gettext("authentication method %u not supported\n"), areq);
981  return STATUS_ERROR;
982  }
983 
984  return STATUS_OK;
985 }
986 
987 
988 /*
989  * pg_fe_getauthname
990  *
991  * Returns a pointer to malloc'd space containing whatever name the user
992  * has authenticated to the system. If there is an error, return NULL,
993  * and put a suitable error message in *errorMessage if that's not NULL.
994  */
995 char *
997 {
998  char *result = NULL;
999  const char *name = NULL;
1000 
1001 #ifdef WIN32
1002  /* Microsoft recommends buffer size of UNLEN+1, where UNLEN = 256 */
1003  char username[256 + 1];
1004  DWORD namesize = sizeof(username);
1005 #else
1006  uid_t user_id = geteuid();
1007  char pwdbuf[BUFSIZ];
1008  struct passwd pwdstr;
1009  struct passwd *pw = NULL;
1010  int pwerr;
1011 #endif
1012 
1013  /*
1014  * Some users are using configure --enable-thread-safety-force, so we
1015  * might as well do the locking within our library to protect
1016  * pqGetpwuid(). In fact, application developers can use getpwuid() in
1017  * their application if they use the locking call we provide, or install
1018  * their own locking function using PQregisterThreadLock().
1019  */
1020  pglock_thread();
1021 
1022 #ifdef WIN32
1023  if (GetUserName(username, &namesize))
1024  name = username;
1025  else if (errorMessage)
1026  printfPQExpBuffer(errorMessage,
1027  libpq_gettext("user name lookup failure: error code %lu\n"),
1028  GetLastError());
1029 #else
1030  pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw);
1031  if (pw != NULL)
1032  name = pw->pw_name;
1033  else if (errorMessage)
1034  {
1035  if (pwerr != 0)
1036  printfPQExpBuffer(errorMessage,
1037  libpq_gettext("could not look up local user ID %d: %s\n"),
1038  (int) user_id,
1039  strerror_r(pwerr, pwdbuf, sizeof(pwdbuf)));
1040  else
1041  printfPQExpBuffer(errorMessage,
1042  libpq_gettext("local user with ID %d does not exist\n"),
1043  (int) user_id);
1044  }
1045 #endif
1046 
1047  if (name)
1048  {
1049  result = strdup(name);
1050  if (result == NULL && errorMessage)
1051  printfPQExpBuffer(errorMessage,
1052  libpq_gettext("out of memory\n"));
1053  }
1054 
1055  pgunlock_thread();
1056 
1057  return result;
1058 }
1059 
1060 
1061 /*
1062  * PQencryptPassword -- exported routine to encrypt a password with MD5
1063  *
1064  * This function is equivalent to calling PQencryptPasswordConn with
1065  * "md5" as the encryption method, except that this doesn't require
1066  * a connection object. This function is deprecated, use
1067  * PQencryptPasswordConn instead.
1068  */
1069 char *
1070 PQencryptPassword(const char *passwd, const char *user)
1071 {
1072  char *crypt_pwd;
1073 
1074  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1075  if (!crypt_pwd)
1076  return NULL;
1077 
1078  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1079  {
1080  free(crypt_pwd);
1081  return NULL;
1082  }
1083 
1084  return crypt_pwd;
1085 }
1086 
1087 /*
1088  * PQencryptPasswordConn -- exported routine to encrypt a password
1089  *
1090  * This is intended to be used by client applications that wish to send
1091  * commands like ALTER USER joe PASSWORD 'pwd'. The password need not
1092  * be sent in cleartext if it is encrypted on the client side. This is
1093  * good because it ensures the cleartext password won't end up in logs,
1094  * pg_stat displays, etc. We export the function so that clients won't
1095  * be dependent on low-level details like whether the encryption is MD5
1096  * or something else.
1097  *
1098  * Arguments are a connection object, the cleartext password, the SQL
1099  * name of the user it is for, and a string indicating the algorithm to
1100  * use for encrypting the password. If algorithm is NULL, this queries
1101  * the server for the current 'password_encryption' value. If you wish
1102  * to avoid that, e.g. to avoid blocking, you can execute
1103  * 'show password_encryption' yourself before calling this function, and
1104  * pass it as the algorithm.
1105  *
1106  * Return value is a malloc'd string. The client may assume the string
1107  * doesn't contain any special characters that would require escaping.
1108  * On error, an error message is stored in the connection object, and
1109  * returns NULL.
1110  */
1111 char *
1112 PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user,
1113  const char *algorithm)
1114 {
1115 #define MAX_ALGORITHM_NAME_LEN 50
1116  char algobuf[MAX_ALGORITHM_NAME_LEN + 1];
1117  char *crypt_pwd = NULL;
1118 
1119  if (!conn)
1120  return NULL;
1121 
1122  /* If no algorithm was given, ask the server. */
1123  if (algorithm == NULL)
1124  {
1125  PGresult *res;
1126  char *val;
1127 
1128  res = PQexec(conn, "show password_encryption");
1129  if (res == NULL)
1130  {
1131  /* PQexec() should've set conn->errorMessage already */
1132  return NULL;
1133  }
1134  if (PQresultStatus(res) != PGRES_TUPLES_OK)
1135  {
1136  /* PQexec() should've set conn->errorMessage already */
1137  PQclear(res);
1138  return NULL;
1139  }
1140  if (PQntuples(res) != 1 || PQnfields(res) != 1)
1141  {
1142  PQclear(res);
1144  libpq_gettext("unexpected shape of result set returned for SHOW\n"));
1145  return NULL;
1146  }
1147  val = PQgetvalue(res, 0, 0);
1148 
1149  if (strlen(val) > MAX_ALGORITHM_NAME_LEN)
1150  {
1151  PQclear(res);
1153  libpq_gettext("password_encryption value too long\n"));
1154  return NULL;
1155  }
1156  strcpy(algobuf, val);
1157  PQclear(res);
1158 
1159  algorithm = algobuf;
1160  }
1161 
1162  /*
1163  * Also accept "on" and "off" as aliases for "md5", because
1164  * password_encryption was a boolean before PostgreSQL 10. We refuse to
1165  * send the password in plaintext even if it was "off".
1166  */
1167  if (strcmp(algorithm, "on") == 0 ||
1168  strcmp(algorithm, "off") == 0)
1169  algorithm = "md5";
1170 
1171  /*
1172  * Ok, now we know what algorithm to use
1173  */
1174  if (strcmp(algorithm, "scram-sha-256") == 0)
1175  {
1176  crypt_pwd = pg_fe_scram_build_verifier(passwd);
1177  }
1178  else if (strcmp(algorithm, "md5") == 0)
1179  {
1180  crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1181  if (crypt_pwd)
1182  {
1183  if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
1184  {
1185  free(crypt_pwd);
1186  crypt_pwd = NULL;
1187  }
1188  }
1189  }
1190  else
1191  {
1193  libpq_gettext("unrecognized password encryption algorithm \"%s\"\n"),
1194  algorithm);
1195  return NULL;
1196  }
1197 
1198  if (!crypt_pwd)
1200  libpq_gettext("out of memory\n"));
1201 
1202  return crypt_pwd;
1203 }
int pqFlush(PGconn *conn)
Definition: fe-misc.c:998
static char password[100]
Definition: streamutil.c:55
int PQnfields(const PGresult *res)
Definition: fe-exec.c:2778
#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)
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#define SCRAM_SHA_256_NAME
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static int pg_local_sendauth(PGconn *conn)
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#define AUTH_REQ_SASL_FIN
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int pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
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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:519
static int pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
Definition: fe-auth.c:713
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int pqGetnchar(char *s, size_t len, PGconn *conn)
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#define PG_PROTOCOL_MAJOR(v)
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Definition: fe-exec.c:2770
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#define AUTH_REQ_MD5
Definition: pqcomm.h:170
ExecStatusType PQresultStatus(const PGresult *res)
Definition: fe-exec.c:2693
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Definition: fe-auth.c:591
#define malloc(a)
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Definition: fe-misc.c:307
#define MAX_ALGORITHM_NAME_LEN
#define sprintf
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Definition: md5.c:323
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#define SCRAM_SHA_256_PLUS_NAME
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#define AUTH_REQ_CRYPT
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char * pguser
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#define STATUS_OK
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#define AUTH_REQ_PASSWORD
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Definition: fe-auth.c:996
PQExpBufferData errorMessage
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static char * username
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#define AUTH_REQ_SASL_CONT
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Definition: fe-exec.c:695
#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)
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#define AUTH_REQ_KRB4
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#define strerror_r
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ProtocolVersion pversion
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char * PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user, const char *algorithm)
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Definition: fe-misc.c:587
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Definition: fe-auth-scram.c:75
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#define AUTH_REQ_SASL
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#define AUTH_REQ_GSS_CONT
Definition: pqcomm.h:173
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static char * user
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static bool success
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