Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * fe-auth.c
4 : * The front-end (client) authorization routines
5 : *
6 : * Portions Copyright (c) 1996-2025, 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 <limits.h>
31 : #include <pwd.h>
32 : #include <sys/param.h> /* for MAXHOSTNAMELEN on most */
33 : #include <sys/socket.h>
34 : #ifdef HAVE_SYS_UCRED_H
35 : #include <sys/ucred.h>
36 : #endif
37 : #ifndef MAXHOSTNAMELEN
38 : #include <netdb.h> /* for MAXHOSTNAMELEN on some */
39 : #endif
40 : #endif
41 :
42 : #include "common/md5.h"
43 : #include "common/scram-common.h"
44 : #include "fe-auth.h"
45 : #include "fe-auth-sasl.h"
46 : #include "libpq-fe.h"
47 :
48 : #ifdef ENABLE_GSS
49 : /*
50 : * GSSAPI authentication system.
51 : */
52 :
53 : #include "fe-gssapi-common.h"
54 :
55 : /*
56 : * Continue GSS authentication with next token as needed.
57 : */
58 : static int
59 : pg_GSS_continue(PGconn *conn, int payloadlen)
60 : {
61 : OM_uint32 maj_stat,
62 : min_stat,
63 : lmin_s,
64 : gss_flags = GSS_C_MUTUAL_FLAG;
65 : gss_buffer_desc ginbuf;
66 : gss_buffer_desc goutbuf;
67 :
68 : /*
69 : * On first call, there's no input token. On subsequent calls, read the
70 : * input token into a GSS buffer.
71 : */
72 : if (conn->gctx != GSS_C_NO_CONTEXT)
73 : {
74 : ginbuf.length = payloadlen;
75 : ginbuf.value = malloc(payloadlen);
76 : if (!ginbuf.value)
77 : {
78 : libpq_append_conn_error(conn, "out of memory allocating GSSAPI buffer (%d)",
79 : payloadlen);
80 : return STATUS_ERROR;
81 : }
82 : if (pqGetnchar(ginbuf.value, payloadlen, conn))
83 : {
84 : /*
85 : * Shouldn't happen, because the caller should've ensured that the
86 : * whole message is already in the input buffer.
87 : */
88 : free(ginbuf.value);
89 : return STATUS_ERROR;
90 : }
91 : }
92 : else
93 : {
94 : ginbuf.length = 0;
95 : ginbuf.value = NULL;
96 : }
97 :
98 : /* finished parsing, trace server-to-client message */
99 : if (conn->Pfdebug)
100 : pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
101 :
102 : /* Only try to acquire credentials if GSS delegation isn't disabled. */
103 : if (!pg_GSS_have_cred_cache(&conn->gcred))
104 : conn->gcred = GSS_C_NO_CREDENTIAL;
105 :
106 : if (conn->gssdelegation && conn->gssdelegation[0] == '1')
107 : gss_flags |= GSS_C_DELEG_FLAG;
108 :
109 : maj_stat = gss_init_sec_context(&min_stat,
110 : conn->gcred,
111 : &conn->gctx,
112 : conn->gtarg_nam,
113 : GSS_C_NO_OID,
114 : gss_flags,
115 : 0,
116 : GSS_C_NO_CHANNEL_BINDINGS,
117 : (ginbuf.value == NULL) ? GSS_C_NO_BUFFER : &ginbuf,
118 : NULL,
119 : &goutbuf,
120 : NULL,
121 : NULL);
122 :
123 : free(ginbuf.value);
124 :
125 : if (goutbuf.length != 0)
126 : {
127 : /*
128 : * GSS generated data to send to the server. We don't care if it's the
129 : * first or subsequent packet, just send the same kind of password
130 : * packet.
131 : */
132 : conn->current_auth_response = AUTH_RESPONSE_GSS;
133 : if (pqPacketSend(conn, PqMsg_GSSResponse,
134 : goutbuf.value, goutbuf.length) != STATUS_OK)
135 : {
136 : gss_release_buffer(&lmin_s, &goutbuf);
137 : return STATUS_ERROR;
138 : }
139 : }
140 : gss_release_buffer(&lmin_s, &goutbuf);
141 :
142 : if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
143 : {
144 : pg_GSS_error(libpq_gettext("GSSAPI continuation error"),
145 : conn,
146 : maj_stat, min_stat);
147 : gss_release_name(&lmin_s, &conn->gtarg_nam);
148 : if (conn->gctx)
149 : gss_delete_sec_context(&lmin_s, &conn->gctx, GSS_C_NO_BUFFER);
150 : return STATUS_ERROR;
151 : }
152 :
153 : if (maj_stat == GSS_S_COMPLETE)
154 : {
155 : conn->client_finished_auth = true;
156 : gss_release_name(&lmin_s, &conn->gtarg_nam);
157 : conn->gssapi_used = true;
158 : }
159 :
160 : return STATUS_OK;
161 : }
162 :
163 : /*
164 : * Send initial GSS authentication token
165 : */
166 : static int
167 : pg_GSS_startup(PGconn *conn, int payloadlen)
168 : {
169 : int ret;
170 : char *host = conn->connhost[conn->whichhost].host;
171 :
172 : if (!(host && host[0] != '\0'))
173 : {
174 : libpq_append_conn_error(conn, "host name must be specified");
175 : return STATUS_ERROR;
176 : }
177 :
178 : if (conn->gctx)
179 : {
180 : libpq_append_conn_error(conn, "duplicate GSS authentication request");
181 : return STATUS_ERROR;
182 : }
183 :
184 : ret = pg_GSS_load_servicename(conn);
185 : if (ret != STATUS_OK)
186 : return ret;
187 :
188 : /*
189 : * Initial packet is the same as a continuation packet with no initial
190 : * context.
191 : */
192 : conn->gctx = GSS_C_NO_CONTEXT;
193 :
194 : return pg_GSS_continue(conn, payloadlen);
195 : }
196 : #endif /* ENABLE_GSS */
197 :
198 :
199 : #ifdef ENABLE_SSPI
200 : /*
201 : * SSPI authentication system (Windows only)
202 : */
203 :
204 : static void
205 : pg_SSPI_error(PGconn *conn, const char *mprefix, SECURITY_STATUS r)
206 : {
207 : char sysmsg[256];
208 :
209 : if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
210 : FORMAT_MESSAGE_FROM_SYSTEM,
211 : NULL, r, 0,
212 : sysmsg, sizeof(sysmsg), NULL) == 0)
213 : appendPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x\n",
214 : mprefix, (unsigned int) r);
215 : else
216 : appendPQExpBuffer(&conn->errorMessage, "%s: %s (%x)\n",
217 : mprefix, sysmsg, (unsigned int) r);
218 : }
219 :
220 : /*
221 : * Continue SSPI authentication with next token as needed.
222 : */
223 : static int
224 : pg_SSPI_continue(PGconn *conn, int payloadlen)
225 : {
226 : SECURITY_STATUS r;
227 : CtxtHandle newContext;
228 : ULONG contextAttr;
229 : SecBufferDesc inbuf;
230 : SecBufferDesc outbuf;
231 : SecBuffer OutBuffers[1];
232 : SecBuffer InBuffers[1];
233 : char *inputbuf = NULL;
234 :
235 : if (conn->sspictx != NULL)
236 : {
237 : /*
238 : * On runs other than the first we have some data to send. Put this
239 : * data in a SecBuffer type structure.
240 : */
241 : inputbuf = malloc(payloadlen);
242 : if (!inputbuf)
243 : {
244 : libpq_append_conn_error(conn, "out of memory allocating SSPI buffer (%d)",
245 : payloadlen);
246 : return STATUS_ERROR;
247 : }
248 : if (pqGetnchar(inputbuf, payloadlen, conn))
249 : {
250 : /*
251 : * Shouldn't happen, because the caller should've ensured that the
252 : * whole message is already in the input buffer.
253 : */
254 : free(inputbuf);
255 : return STATUS_ERROR;
256 : }
257 :
258 : inbuf.ulVersion = SECBUFFER_VERSION;
259 : inbuf.cBuffers = 1;
260 : inbuf.pBuffers = InBuffers;
261 : InBuffers[0].pvBuffer = inputbuf;
262 : InBuffers[0].cbBuffer = payloadlen;
263 : InBuffers[0].BufferType = SECBUFFER_TOKEN;
264 : }
265 :
266 : /* finished parsing, trace server-to-client message */
267 : if (conn->Pfdebug)
268 : pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
269 :
270 : OutBuffers[0].pvBuffer = NULL;
271 : OutBuffers[0].BufferType = SECBUFFER_TOKEN;
272 : OutBuffers[0].cbBuffer = 0;
273 : outbuf.cBuffers = 1;
274 : outbuf.pBuffers = OutBuffers;
275 : outbuf.ulVersion = SECBUFFER_VERSION;
276 :
277 : r = InitializeSecurityContext(conn->sspicred,
278 : conn->sspictx,
279 : conn->sspitarget,
280 : ISC_REQ_ALLOCATE_MEMORY,
281 : 0,
282 : SECURITY_NETWORK_DREP,
283 : (conn->sspictx == NULL) ? NULL : &inbuf,
284 : 0,
285 : &newContext,
286 : &outbuf,
287 : &contextAttr,
288 : NULL);
289 :
290 : /* we don't need the input anymore */
291 : free(inputbuf);
292 :
293 : if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED)
294 : {
295 : pg_SSPI_error(conn, libpq_gettext("SSPI continuation error"), r);
296 :
297 : return STATUS_ERROR;
298 : }
299 :
300 : if (conn->sspictx == NULL)
301 : {
302 : /* On first run, transfer retrieved context handle */
303 : conn->sspictx = malloc(sizeof(CtxtHandle));
304 : if (conn->sspictx == NULL)
305 : {
306 : libpq_append_conn_error(conn, "out of memory");
307 : return STATUS_ERROR;
308 : }
309 : memcpy(conn->sspictx, &newContext, sizeof(CtxtHandle));
310 : }
311 :
312 : /*
313 : * If SSPI returned any data to be sent to the server (as it normally
314 : * would), send this data as a password packet.
315 : */
316 : if (outbuf.cBuffers > 0)
317 : {
318 : if (outbuf.cBuffers != 1)
319 : {
320 : /*
321 : * This should never happen, at least not for Kerberos
322 : * authentication. Keep check in case it shows up with other
323 : * authentication methods later.
324 : */
325 : appendPQExpBufferStr(&conn->errorMessage,
326 : "SSPI returned invalid number of output buffers\n");
327 : return STATUS_ERROR;
328 : }
329 :
330 : /*
331 : * If the negotiation is complete, there may be zero bytes to send.
332 : * The server is at this point not expecting any more data, so don't
333 : * send it.
334 : */
335 : if (outbuf.pBuffers[0].cbBuffer > 0)
336 : {
337 : conn->current_auth_response = AUTH_RESPONSE_GSS;
338 : if (pqPacketSend(conn, PqMsg_GSSResponse,
339 : outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer))
340 : {
341 : FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
342 : return STATUS_ERROR;
343 : }
344 : }
345 : FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
346 : }
347 :
348 : if (r == SEC_E_OK)
349 : conn->client_finished_auth = true;
350 :
351 : /* Cleanup is handled by the code in freePGconn() */
352 : return STATUS_OK;
353 : }
354 :
355 : /*
356 : * Send initial SSPI authentication token.
357 : * If use_negotiate is 0, use kerberos authentication package which is
358 : * compatible with Unix. If use_negotiate is 1, use the negotiate package
359 : * which supports both kerberos and NTLM, but is not compatible with Unix.
360 : */
361 : static int
362 : pg_SSPI_startup(PGconn *conn, int use_negotiate, int payloadlen)
363 : {
364 : SECURITY_STATUS r;
365 : TimeStamp expire;
366 : char *host = conn->connhost[conn->whichhost].host;
367 :
368 : if (conn->sspictx)
369 : {
370 : libpq_append_conn_error(conn, "duplicate SSPI authentication request");
371 : return STATUS_ERROR;
372 : }
373 :
374 : /*
375 : * Retrieve credentials handle
376 : */
377 : conn->sspicred = malloc(sizeof(CredHandle));
378 : if (conn->sspicred == NULL)
379 : {
380 : libpq_append_conn_error(conn, "out of memory");
381 : return STATUS_ERROR;
382 : }
383 :
384 : r = AcquireCredentialsHandle(NULL,
385 : use_negotiate ? "negotiate" : "kerberos",
386 : SECPKG_CRED_OUTBOUND,
387 : NULL,
388 : NULL,
389 : NULL,
390 : NULL,
391 : conn->sspicred,
392 : &expire);
393 : if (r != SEC_E_OK)
394 : {
395 : pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r);
396 : free(conn->sspicred);
397 : conn->sspicred = NULL;
398 : return STATUS_ERROR;
399 : }
400 :
401 : /*
402 : * Compute target principal name. SSPI has a different format from GSSAPI,
403 : * but not more complex. We can skip the @REALM part, because Windows will
404 : * fill that in for us automatically.
405 : */
406 : if (!(host && host[0] != '\0'))
407 : {
408 : libpq_append_conn_error(conn, "host name must be specified");
409 : return STATUS_ERROR;
410 : }
411 : conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2);
412 : if (!conn->sspitarget)
413 : {
414 : libpq_append_conn_error(conn, "out of memory");
415 : return STATUS_ERROR;
416 : }
417 : sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, host);
418 :
419 : /*
420 : * Indicate that we're in SSPI authentication mode to make sure that
421 : * pg_SSPI_continue is called next time in the negotiation.
422 : */
423 : conn->usesspi = 1;
424 :
425 : return pg_SSPI_continue(conn, payloadlen);
426 : }
427 : #endif /* ENABLE_SSPI */
428 :
429 : /*
430 : * Initialize SASL authentication exchange.
431 : */
432 : static int
433 100 : pg_SASL_init(PGconn *conn, int payloadlen)
434 : {
435 100 : char *initialresponse = NULL;
436 : int initialresponselen;
437 : const char *selected_mechanism;
438 : PQExpBufferData mechanism_buf;
439 100 : char *password = NULL;
440 : SASLStatus status;
441 :
442 100 : initPQExpBuffer(&mechanism_buf);
443 :
444 100 : if (conn->channel_binding[0] == 'r' && /* require */
445 8 : !conn->ssl_in_use)
446 : {
447 2 : libpq_append_conn_error(conn, "channel binding required, but SSL not in use");
448 2 : goto error;
449 : }
450 :
451 98 : if (conn->sasl_state)
452 : {
453 0 : libpq_append_conn_error(conn, "duplicate SASL authentication request");
454 0 : goto error;
455 : }
456 :
457 : /*
458 : * Parse the list of SASL authentication mechanisms in the
459 : * AuthenticationSASL message, and select the best mechanism that we
460 : * support. Mechanisms are listed by order of decreasing importance.
461 : */
462 98 : selected_mechanism = NULL;
463 : for (;;)
464 : {
465 210 : if (pqGets(&mechanism_buf, conn))
466 : {
467 0 : appendPQExpBufferStr(&conn->errorMessage,
468 : "fe_sendauth: invalid authentication request from server: invalid list of authentication mechanisms\n");
469 0 : goto error;
470 : }
471 210 : if (PQExpBufferDataBroken(mechanism_buf))
472 0 : goto oom_error;
473 :
474 : /* An empty string indicates end of list */
475 210 : if (mechanism_buf.data[0] == '\0')
476 98 : break;
477 :
478 : /*
479 : * Select the mechanism to use. Pick SCRAM-SHA-256-PLUS over anything
480 : * else if a channel binding type is set and if the client supports it
481 : * (and did not set channel_binding=disable). Pick SCRAM-SHA-256 if
482 : * nothing else has already been picked. If we add more mechanisms, a
483 : * more refined priority mechanism might become necessary.
484 : */
485 112 : if (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0)
486 : {
487 14 : if (conn->ssl_in_use)
488 : {
489 : /* The server has offered SCRAM-SHA-256-PLUS. */
490 :
491 : #ifdef USE_SSL
492 : /*
493 : * The client supports channel binding, which is chosen if
494 : * channel_binding is not disabled.
495 : */
496 14 : if (conn->channel_binding[0] != 'd') /* disable */
497 : {
498 10 : selected_mechanism = SCRAM_SHA_256_PLUS_NAME;
499 10 : conn->sasl = &pg_scram_mech;
500 10 : conn->password_needed = true;
501 : }
502 : #else
503 : /*
504 : * The client does not support channel binding. If it is
505 : * required, complain immediately instead of the error below
506 : * which would be confusing as the server is publishing
507 : * SCRAM-SHA-256-PLUS.
508 : */
509 : if (conn->channel_binding[0] == 'r') /* require */
510 : {
511 : libpq_append_conn_error(conn, "channel binding is required, but client does not support it");
512 : goto error;
513 : }
514 : #endif
515 : }
516 : else
517 : {
518 : /*
519 : * The server offered SCRAM-SHA-256-PLUS, but the connection
520 : * is not SSL-encrypted. That's not sane. Perhaps SSL was
521 : * stripped by a proxy? There's no point in continuing,
522 : * because the server will reject the connection anyway if we
523 : * try authenticate without channel binding even though both
524 : * the client and server supported it. The SCRAM exchange
525 : * checks for that, to prevent downgrade attacks.
526 : */
527 0 : libpq_append_conn_error(conn, "server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection");
528 0 : goto error;
529 : }
530 : }
531 98 : else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 &&
532 : !selected_mechanism)
533 : {
534 88 : selected_mechanism = SCRAM_SHA_256_NAME;
535 88 : conn->sasl = &pg_scram_mech;
536 88 : conn->password_needed = true;
537 : }
538 : }
539 :
540 98 : if (!selected_mechanism)
541 : {
542 0 : libpq_append_conn_error(conn, "none of the server's SASL authentication mechanisms are supported");
543 0 : goto error;
544 : }
545 :
546 98 : if (conn->channel_binding[0] == 'r' && /* require */
547 6 : strcmp(selected_mechanism, SCRAM_SHA_256_PLUS_NAME) != 0)
548 : {
549 0 : libpq_append_conn_error(conn, "channel binding is required, but server did not offer an authentication method that supports channel binding");
550 0 : goto error;
551 : }
552 :
553 : /*
554 : * Now that the SASL mechanism has been chosen for the exchange,
555 : * initialize its state information.
556 : */
557 :
558 : /*
559 : * First, select the password to use for the exchange, complaining if
560 : * there isn't one and the selected SASL mechanism needs it.
561 : */
562 98 : if (conn->password_needed && !conn->scram_client_key_binary)
563 : {
564 90 : password = conn->connhost[conn->whichhost].password;
565 90 : if (password == NULL)
566 90 : password = conn->pgpass;
567 90 : if (password == NULL || password[0] == '\0')
568 : {
569 0 : appendPQExpBufferStr(&conn->errorMessage,
570 : PQnoPasswordSupplied);
571 0 : goto error;
572 : }
573 : }
574 :
575 : /* finished parsing, trace server-to-client message */
576 98 : if (conn->Pfdebug)
577 0 : pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
578 :
579 : Assert(conn->sasl);
580 :
581 : /*
582 : * Initialize the SASL state information with all the information gathered
583 : * during the initial exchange.
584 : *
585 : * Note: Only tls-unique is supported for the moment.
586 : */
587 98 : conn->sasl_state = conn->sasl->init(conn,
588 : password,
589 : selected_mechanism);
590 98 : if (!conn->sasl_state)
591 0 : goto oom_error;
592 :
593 : /* Get the mechanism-specific Initial Client Response, if any */
594 98 : status = conn->sasl->exchange(conn->sasl_state,
595 : NULL, -1,
596 : &initialresponse, &initialresponselen);
597 :
598 98 : if (status == SASL_FAILED)
599 0 : goto error;
600 :
601 : /*
602 : * Build a SASLInitialResponse message, and send it.
603 : */
604 98 : if (pqPutMsgStart(PqMsg_SASLInitialResponse, conn))
605 0 : goto error;
606 98 : if (pqPuts(selected_mechanism, conn))
607 0 : goto error;
608 98 : if (initialresponse)
609 : {
610 98 : if (pqPutInt(initialresponselen, 4, conn))
611 0 : goto error;
612 98 : if (pqPutnchar(initialresponse, initialresponselen, conn))
613 0 : goto error;
614 : }
615 98 : conn->current_auth_response = AUTH_RESPONSE_SASL_INITIAL;
616 98 : if (pqPutMsgEnd(conn))
617 0 : goto error;
618 :
619 98 : if (pqFlush(conn))
620 0 : goto error;
621 :
622 98 : termPQExpBuffer(&mechanism_buf);
623 98 : free(initialresponse);
624 :
625 98 : return STATUS_OK;
626 :
627 2 : error:
628 2 : termPQExpBuffer(&mechanism_buf);
629 2 : free(initialresponse);
630 2 : return STATUS_ERROR;
631 :
632 0 : oom_error:
633 0 : termPQExpBuffer(&mechanism_buf);
634 0 : free(initialresponse);
635 0 : libpq_append_conn_error(conn, "out of memory");
636 0 : return STATUS_ERROR;
637 : }
638 :
639 : /*
640 : * Exchange a message for SASL communication protocol with the backend.
641 : * This should be used after calling pg_SASL_init to set up the status of
642 : * the protocol.
643 : */
644 : static int
645 184 : pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
646 : {
647 : char *output;
648 : int outputlen;
649 : int res;
650 : char *challenge;
651 : SASLStatus status;
652 :
653 : /* Read the SASL challenge from the AuthenticationSASLContinue message. */
654 184 : challenge = malloc(payloadlen + 1);
655 184 : if (!challenge)
656 : {
657 0 : libpq_append_conn_error(conn, "out of memory allocating SASL buffer (%d)",
658 : payloadlen);
659 0 : return STATUS_ERROR;
660 : }
661 :
662 184 : if (pqGetnchar(challenge, payloadlen, conn))
663 : {
664 0 : free(challenge);
665 0 : return STATUS_ERROR;
666 : }
667 :
668 : /* finished parsing, trace server-to-client message */
669 184 : if (conn->Pfdebug)
670 0 : pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
671 :
672 : /* For safety and convenience, ensure the buffer is NULL-terminated. */
673 184 : challenge[payloadlen] = '\0';
674 :
675 184 : status = conn->sasl->exchange(conn->sasl_state,
676 : challenge, payloadlen,
677 : &output, &outputlen);
678 184 : free(challenge); /* don't need the input anymore */
679 :
680 184 : if (final && status == SASL_CONTINUE)
681 : {
682 0 : if (outputlen != 0)
683 0 : free(output);
684 :
685 0 : libpq_append_conn_error(conn, "AuthenticationSASLFinal received from server, but SASL authentication was not completed");
686 0 : return STATUS_ERROR;
687 : }
688 :
689 : /*
690 : * If the exchange is not completed yet, we need to make sure that the
691 : * SASL mechanism has generated a message to send back.
692 : */
693 184 : if (output == NULL && status == SASL_CONTINUE)
694 : {
695 0 : libpq_append_conn_error(conn, "no client response found after SASL exchange success");
696 0 : return STATUS_ERROR;
697 : }
698 :
699 : /*
700 : * SASL allows zero-length responses, so this check uses "output" and not
701 : * "outputlen" to allow the case of an empty message.
702 : */
703 184 : if (output)
704 : {
705 : /*
706 : * Send the SASL response to the server.
707 : */
708 98 : conn->current_auth_response = AUTH_RESPONSE_SASL;
709 98 : res = pqPacketSend(conn, PqMsg_SASLResponse, output, outputlen);
710 98 : free(output);
711 :
712 98 : if (res != STATUS_OK)
713 0 : return STATUS_ERROR;
714 : }
715 :
716 184 : if (status == SASL_FAILED)
717 0 : return STATUS_ERROR;
718 :
719 184 : return STATUS_OK;
720 : }
721 :
722 : static int
723 84 : pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
724 : {
725 : int ret;
726 84 : char *crypt_pwd = NULL;
727 : const char *pwd_to_send;
728 : char md5Salt[4];
729 :
730 : /* Read the salt from the AuthenticationMD5Password message. */
731 84 : if (areq == AUTH_REQ_MD5)
732 : {
733 2 : if (pqGetnchar(md5Salt, 4, conn))
734 0 : return STATUS_ERROR; /* shouldn't happen */
735 : }
736 :
737 : /* finished parsing, trace server-to-client message */
738 84 : if (conn->Pfdebug)
739 0 : pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
740 :
741 : /* Encrypt the password if needed. */
742 :
743 84 : switch (areq)
744 : {
745 2 : case AUTH_REQ_MD5:
746 : {
747 : char *crypt_pwd2;
748 2 : const char *errstr = NULL;
749 :
750 : /* Allocate enough space for two MD5 hashes */
751 2 : crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
752 2 : if (!crypt_pwd)
753 : {
754 0 : libpq_append_conn_error(conn, "out of memory");
755 0 : return STATUS_ERROR;
756 : }
757 :
758 2 : crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
759 2 : if (!pg_md5_encrypt(password, conn->pguser,
760 2 : strlen(conn->pguser), crypt_pwd2,
761 : &errstr))
762 : {
763 0 : libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
764 0 : free(crypt_pwd);
765 0 : return STATUS_ERROR;
766 : }
767 2 : if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt,
768 : 4, crypt_pwd, &errstr))
769 : {
770 0 : libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
771 0 : free(crypt_pwd);
772 0 : return STATUS_ERROR;
773 : }
774 :
775 2 : pwd_to_send = crypt_pwd;
776 2 : break;
777 : }
778 82 : case AUTH_REQ_PASSWORD:
779 82 : pwd_to_send = password;
780 82 : break;
781 0 : default:
782 0 : return STATUS_ERROR;
783 : }
784 84 : conn->current_auth_response = AUTH_RESPONSE_PASSWORD;
785 84 : ret = pqPacketSend(conn, PqMsg_PasswordMessage,
786 84 : pwd_to_send, strlen(pwd_to_send) + 1);
787 84 : free(crypt_pwd);
788 84 : return ret;
789 : }
790 :
791 : /*
792 : * Translate a disallowed AuthRequest code into an error message.
793 : */
794 : static const char *
795 32 : auth_method_description(AuthRequest areq)
796 : {
797 32 : switch (areq)
798 : {
799 12 : case AUTH_REQ_PASSWORD:
800 12 : return libpq_gettext("server requested a cleartext password");
801 0 : case AUTH_REQ_MD5:
802 0 : return libpq_gettext("server requested a hashed password");
803 0 : case AUTH_REQ_GSS:
804 : case AUTH_REQ_GSS_CONT:
805 0 : return libpq_gettext("server requested GSSAPI authentication");
806 0 : case AUTH_REQ_SSPI:
807 0 : return libpq_gettext("server requested SSPI authentication");
808 20 : case AUTH_REQ_SASL:
809 : case AUTH_REQ_SASL_CONT:
810 : case AUTH_REQ_SASL_FIN:
811 20 : return libpq_gettext("server requested SASL authentication");
812 : }
813 :
814 0 : return libpq_gettext("server requested an unknown authentication type");
815 : }
816 :
817 : /*
818 : * Convenience macro for checking the allowed_auth_methods bitmask. Caller
819 : * must ensure that type is not greater than 31 (high bit of the bitmask).
820 : */
821 : #define auth_method_allowed(conn, type) \
822 : (((conn)->allowed_auth_methods & (1 << (type))) != 0)
823 :
824 : /*
825 : * Verify that the authentication request is expected, given the connection
826 : * parameters. This is especially important when the client wishes to
827 : * authenticate the server before any sensitive information is exchanged.
828 : */
829 : static bool
830 23902 : check_expected_areq(AuthRequest areq, PGconn *conn)
831 : {
832 23902 : bool result = true;
833 23902 : const char *reason = NULL;
834 :
835 : StaticAssertDecl((sizeof(conn->allowed_auth_methods) * CHAR_BIT) > AUTH_REQ_MAX,
836 : "AUTH_REQ_MAX overflows the allowed_auth_methods bitmask");
837 :
838 23902 : if (conn->sslcertmode[0] == 'r' /* require */
839 6 : && areq == AUTH_REQ_OK)
840 : {
841 : /*
842 : * Trade off a little bit of complexity to try to get these error
843 : * messages as precise as possible.
844 : */
845 6 : if (!conn->ssl_cert_requested)
846 : {
847 0 : libpq_append_conn_error(conn, "server did not request an SSL certificate");
848 0 : return false;
849 : }
850 6 : else if (!conn->ssl_cert_sent)
851 : {
852 2 : libpq_append_conn_error(conn, "server accepted connection without a valid SSL certificate");
853 2 : return false;
854 : }
855 : }
856 :
857 : /*
858 : * If the user required a specific auth method, or specified an allowed
859 : * set, then reject all others here, and make sure the server actually
860 : * completes an authentication exchange.
861 : */
862 23900 : if (conn->require_auth)
863 : {
864 144 : switch (areq)
865 : {
866 54 : case AUTH_REQ_OK:
867 :
868 : /*
869 : * Check to make sure we've actually finished our exchange (or
870 : * else that the user has allowed an authentication-less
871 : * connection).
872 : *
873 : * If the user has allowed both SCRAM and unauthenticated
874 : * (trust) connections, then this check will silently accept
875 : * partial SCRAM exchanges, where a misbehaving server does
876 : * not provide its verifier before sending an OK. This is
877 : * consistent with historical behavior, but it may be a point
878 : * to revisit in the future, since it could allow a server
879 : * that doesn't know the user's password to silently harvest
880 : * material for a brute force attack.
881 : */
882 54 : if (!conn->auth_required || conn->client_finished_auth)
883 : break;
884 :
885 : /*
886 : * No explicit authentication request was made by the server
887 : * -- or perhaps it was made and not completed, in the case of
888 : * SCRAM -- but there is one special case to check. If the
889 : * user allowed "gss", then a GSS-encrypted channel also
890 : * satisfies the check.
891 : */
892 : #ifdef ENABLE_GSS
893 : if (auth_method_allowed(conn, AUTH_REQ_GSS) && conn->gssenc)
894 : {
895 : /*
896 : * If implicit GSS auth has already been performed via GSS
897 : * encryption, we don't need to have performed an
898 : * AUTH_REQ_GSS exchange. This allows require_auth=gss to
899 : * be combined with gssencmode, since there won't be an
900 : * explicit authentication request in that case.
901 : */
902 : }
903 : else
904 : #endif
905 : {
906 14 : reason = libpq_gettext("server did not complete authentication");
907 14 : result = false;
908 : }
909 :
910 14 : break;
911 :
912 90 : case AUTH_REQ_PASSWORD:
913 : case AUTH_REQ_MD5:
914 : case AUTH_REQ_GSS:
915 : case AUTH_REQ_GSS_CONT:
916 : case AUTH_REQ_SSPI:
917 : case AUTH_REQ_SASL:
918 : case AUTH_REQ_SASL_CONT:
919 : case AUTH_REQ_SASL_FIN:
920 :
921 : /*
922 : * We don't handle these with the default case, to avoid
923 : * bit-shifting past the end of the allowed_auth_methods mask
924 : * if the server sends an unexpected AuthRequest.
925 : */
926 90 : result = auth_method_allowed(conn, areq);
927 90 : break;
928 :
929 0 : default:
930 0 : result = false;
931 0 : break;
932 : }
933 23796 : }
934 :
935 23900 : if (!result)
936 : {
937 46 : if (!reason)
938 32 : reason = auth_method_description(areq);
939 :
940 46 : libpq_append_conn_error(conn, "authentication method requirement \"%s\" failed: %s",
941 : conn->require_auth, reason);
942 46 : return result;
943 : }
944 :
945 : /*
946 : * When channel_binding=require, we must protect against two cases: (1) we
947 : * must not respond to non-SASL authentication requests, which might leak
948 : * information such as the client's password; and (2) even if we receive
949 : * AUTH_REQ_OK, we still must ensure that channel binding has happened in
950 : * order to authenticate the server.
951 : */
952 23854 : if (conn->channel_binding[0] == 'r' /* require */ )
953 : {
954 34 : switch (areq)
955 : {
956 20 : case AUTH_REQ_SASL:
957 : case AUTH_REQ_SASL_CONT:
958 : case AUTH_REQ_SASL_FIN:
959 20 : break;
960 8 : case AUTH_REQ_OK:
961 8 : if (!conn->sasl || !conn->sasl->channel_bound(conn->sasl_state))
962 : {
963 2 : libpq_append_conn_error(conn, "channel binding required, but server authenticated client without channel binding");
964 2 : result = false;
965 : }
966 8 : break;
967 6 : default:
968 6 : libpq_append_conn_error(conn, "channel binding required but not supported by server's authentication request");
969 6 : result = false;
970 6 : break;
971 : }
972 23820 : }
973 :
974 23854 : return result;
975 : }
976 :
977 : /*
978 : * pg_fe_sendauth
979 : * client demux routine for processing an authentication request
980 : *
981 : * The server has sent us an authentication challenge (or OK). Send an
982 : * appropriate response. The caller has ensured that the whole message is
983 : * now in the input buffer, and has already read the type and length of
984 : * it. We are responsible for reading any remaining extra data, specific
985 : * to the authentication method. 'payloadlen' is the remaining length in
986 : * the message.
987 : */
988 : int
989 23902 : pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
990 : {
991 : int oldmsglen;
992 :
993 23902 : if (!check_expected_areq(areq, conn))
994 56 : return STATUS_ERROR;
995 :
996 23846 : switch (areq)
997 : {
998 23476 : case AUTH_REQ_OK:
999 23476 : break;
1000 :
1001 0 : case AUTH_REQ_KRB4:
1002 0 : libpq_append_conn_error(conn, "Kerberos 4 authentication not supported");
1003 0 : return STATUS_ERROR;
1004 :
1005 0 : case AUTH_REQ_KRB5:
1006 0 : libpq_append_conn_error(conn, "Kerberos 5 authentication not supported");
1007 0 : return STATUS_ERROR;
1008 :
1009 : #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
1010 : case AUTH_REQ_GSS:
1011 : #if !defined(ENABLE_SSPI)
1012 : /* no native SSPI, so use GSSAPI library for it */
1013 : case AUTH_REQ_SSPI:
1014 : #endif
1015 : {
1016 : int r;
1017 :
1018 : pglock_thread();
1019 :
1020 : /*
1021 : * If we have both GSS and SSPI support compiled in, use SSPI
1022 : * support by default. This is overridable by a connection
1023 : * string parameter. Note that when using SSPI we still leave
1024 : * the negotiate parameter off, since we want SSPI to use the
1025 : * GSSAPI kerberos protocol. For actual SSPI negotiate
1026 : * protocol, we use AUTH_REQ_SSPI.
1027 : */
1028 : #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
1029 : if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
1030 : r = pg_GSS_startup(conn, payloadlen);
1031 : else
1032 : r = pg_SSPI_startup(conn, 0, payloadlen);
1033 : #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
1034 : r = pg_GSS_startup(conn, payloadlen);
1035 : #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
1036 : r = pg_SSPI_startup(conn, 0, payloadlen);
1037 : #endif
1038 : if (r != STATUS_OK)
1039 : {
1040 : /* Error message already filled in. */
1041 : pgunlock_thread();
1042 : return STATUS_ERROR;
1043 : }
1044 : pgunlock_thread();
1045 : }
1046 : break;
1047 :
1048 : case AUTH_REQ_GSS_CONT:
1049 : {
1050 : int r;
1051 :
1052 : pglock_thread();
1053 : #if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
1054 : if (conn->usesspi)
1055 : r = pg_SSPI_continue(conn, payloadlen);
1056 : else
1057 : r = pg_GSS_continue(conn, payloadlen);
1058 : #elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
1059 : r = pg_GSS_continue(conn, payloadlen);
1060 : #elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
1061 : r = pg_SSPI_continue(conn, payloadlen);
1062 : #endif
1063 : if (r != STATUS_OK)
1064 : {
1065 : /* Error message already filled in. */
1066 : pgunlock_thread();
1067 : return STATUS_ERROR;
1068 : }
1069 : pgunlock_thread();
1070 : }
1071 : break;
1072 : #else /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
1073 : /* No GSSAPI *or* SSPI support */
1074 0 : case AUTH_REQ_GSS:
1075 : case AUTH_REQ_GSS_CONT:
1076 0 : libpq_append_conn_error(conn, "GSSAPI authentication not supported");
1077 0 : return STATUS_ERROR;
1078 : #endif /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
1079 :
1080 : #ifdef ENABLE_SSPI
1081 : case AUTH_REQ_SSPI:
1082 :
1083 : /*
1084 : * SSPI has its own startup message so libpq can decide which
1085 : * method to use. Indicate to pg_SSPI_startup that we want SSPI
1086 : * negotiation instead of Kerberos.
1087 : */
1088 : pglock_thread();
1089 : if (pg_SSPI_startup(conn, 1, payloadlen) != STATUS_OK)
1090 : {
1091 : /* Error message already filled in. */
1092 : pgunlock_thread();
1093 : return STATUS_ERROR;
1094 : }
1095 : pgunlock_thread();
1096 : break;
1097 : #else
1098 :
1099 : /*
1100 : * No SSPI support. However, if we have GSSAPI but not SSPI
1101 : * support, AUTH_REQ_SSPI will have been handled in the codepath
1102 : * for AUTH_REQ_GSS above, so don't duplicate the case label in
1103 : * that case.
1104 : */
1105 : #if !defined(ENABLE_GSS)
1106 0 : case AUTH_REQ_SSPI:
1107 0 : libpq_append_conn_error(conn, "SSPI authentication not supported");
1108 0 : return STATUS_ERROR;
1109 : #endif /* !define(ENABLE_GSS) */
1110 : #endif /* ENABLE_SSPI */
1111 :
1112 :
1113 0 : case AUTH_REQ_CRYPT:
1114 0 : libpq_append_conn_error(conn, "Crypt authentication not supported");
1115 0 : return STATUS_ERROR;
1116 :
1117 86 : case AUTH_REQ_MD5:
1118 : case AUTH_REQ_PASSWORD:
1119 : {
1120 : char *password;
1121 :
1122 86 : conn->password_needed = true;
1123 86 : password = conn->connhost[conn->whichhost].password;
1124 86 : if (password == NULL)
1125 76 : password = conn->pgpass;
1126 86 : if (password == NULL || password[0] == '\0')
1127 : {
1128 2 : appendPQExpBufferStr(&conn->errorMessage,
1129 : PQnoPasswordSupplied);
1130 2 : return STATUS_ERROR;
1131 : }
1132 84 : if (pg_password_sendauth(conn, password, areq) != STATUS_OK)
1133 : {
1134 0 : appendPQExpBufferStr(&conn->errorMessage,
1135 : "fe_sendauth: error sending password authentication\n");
1136 0 : return STATUS_ERROR;
1137 : }
1138 :
1139 : /* We expect no further authentication requests. */
1140 84 : conn->client_finished_auth = true;
1141 84 : break;
1142 : }
1143 :
1144 100 : case AUTH_REQ_SASL:
1145 :
1146 : /*
1147 : * The request contains the name (as assigned by IANA) of the
1148 : * authentication mechanism.
1149 : */
1150 100 : if (pg_SASL_init(conn, payloadlen) != STATUS_OK)
1151 : {
1152 : /* pg_SASL_init already set the error message */
1153 2 : return STATUS_ERROR;
1154 : }
1155 98 : break;
1156 :
1157 184 : case AUTH_REQ_SASL_CONT:
1158 : case AUTH_REQ_SASL_FIN:
1159 184 : if (conn->sasl_state == NULL)
1160 : {
1161 0 : appendPQExpBufferStr(&conn->errorMessage,
1162 : "fe_sendauth: invalid authentication request from server: AUTH_REQ_SASL_CONT without AUTH_REQ_SASL\n");
1163 0 : return STATUS_ERROR;
1164 : }
1165 184 : oldmsglen = conn->errorMessage.len;
1166 184 : if (pg_SASL_continue(conn, payloadlen,
1167 : (areq == AUTH_REQ_SASL_FIN)) != STATUS_OK)
1168 : {
1169 : /* Use this message if pg_SASL_continue didn't supply one */
1170 0 : if (conn->errorMessage.len == oldmsglen)
1171 0 : appendPQExpBufferStr(&conn->errorMessage,
1172 : "fe_sendauth: error in SASL authentication\n");
1173 0 : return STATUS_ERROR;
1174 : }
1175 184 : break;
1176 :
1177 0 : default:
1178 0 : libpq_append_conn_error(conn, "authentication method %u not supported", areq);
1179 0 : return STATUS_ERROR;
1180 : }
1181 :
1182 23842 : return STATUS_OK;
1183 : }
1184 :
1185 :
1186 : /*
1187 : * pg_fe_getusername
1188 : *
1189 : * Returns a pointer to malloc'd space containing the name of the
1190 : * specified user_id. If there is an error, return NULL, and append
1191 : * a suitable error message to *errorMessage if that's not NULL.
1192 : *
1193 : * Caution: on Windows, the user_id argument is ignored, and we always
1194 : * fetch the current user's name.
1195 : */
1196 : char *
1197 22688 : pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage)
1198 : {
1199 22688 : char *result = NULL;
1200 22688 : const char *name = NULL;
1201 :
1202 : #ifdef WIN32
1203 : /* Microsoft recommends buffer size of UNLEN+1, where UNLEN = 256 */
1204 : char username[256 + 1];
1205 : DWORD namesize = sizeof(username);
1206 : #else
1207 : struct passwd pwbuf;
1208 22688 : struct passwd *pw = NULL;
1209 : char buf[1024];
1210 : int rc;
1211 : #endif
1212 :
1213 : #ifdef WIN32
1214 : if (GetUserName(username, &namesize))
1215 : name = username;
1216 : else if (errorMessage)
1217 : libpq_append_error(errorMessage,
1218 : "user name lookup failure: error code %lu",
1219 : GetLastError());
1220 : #else
1221 22688 : rc = getpwuid_r(user_id, &pwbuf, buf, sizeof buf, &pw);
1222 22688 : if (rc != 0)
1223 : {
1224 0 : errno = rc;
1225 0 : if (errorMessage)
1226 0 : libpq_append_error(errorMessage, "could not look up local user ID %ld: %m", (long) user_id);
1227 : }
1228 22688 : else if (!pw)
1229 : {
1230 0 : if (errorMessage)
1231 0 : libpq_append_error(errorMessage, "local user with ID %ld does not exist", (long) user_id);
1232 : }
1233 : else
1234 22688 : name = pw->pw_name;
1235 : #endif
1236 :
1237 22688 : if (name)
1238 : {
1239 22688 : result = strdup(name);
1240 22688 : if (result == NULL && errorMessage)
1241 0 : libpq_append_error(errorMessage, "out of memory");
1242 : }
1243 :
1244 22688 : return result;
1245 : }
1246 :
1247 : /*
1248 : * pg_fe_getauthname
1249 : *
1250 : * Returns a pointer to malloc'd space containing whatever name the user
1251 : * has authenticated to the system. If there is an error, return NULL,
1252 : * and append a suitable error message to *errorMessage if that's not NULL.
1253 : */
1254 : char *
1255 22688 : pg_fe_getauthname(PQExpBuffer errorMessage)
1256 : {
1257 : #ifdef WIN32
1258 : return pg_fe_getusername(0, errorMessage);
1259 : #else
1260 22688 : return pg_fe_getusername(geteuid(), errorMessage);
1261 : #endif
1262 : }
1263 :
1264 :
1265 : /*
1266 : * PQencryptPassword -- exported routine to encrypt a password with MD5
1267 : *
1268 : * This function is equivalent to calling PQencryptPasswordConn with
1269 : * "md5" as the encryption method, except that this doesn't require
1270 : * a connection object. This function is deprecated, use
1271 : * PQencryptPasswordConn instead.
1272 : */
1273 : char *
1274 0 : PQencryptPassword(const char *passwd, const char *user)
1275 : {
1276 : char *crypt_pwd;
1277 0 : const char *errstr = NULL;
1278 :
1279 0 : crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1280 0 : if (!crypt_pwd)
1281 0 : return NULL;
1282 :
1283 0 : if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd, &errstr))
1284 : {
1285 0 : free(crypt_pwd);
1286 0 : return NULL;
1287 : }
1288 :
1289 0 : return crypt_pwd;
1290 : }
1291 :
1292 : /*
1293 : * PQencryptPasswordConn -- exported routine to encrypt a password
1294 : *
1295 : * This is intended to be used by client applications that wish to send
1296 : * commands like ALTER USER joe PASSWORD 'pwd'. The password need not
1297 : * be sent in cleartext if it is encrypted on the client side. This is
1298 : * good because it ensures the cleartext password won't end up in logs,
1299 : * pg_stat displays, etc. We export the function so that clients won't
1300 : * be dependent on low-level details like whether the encryption is MD5
1301 : * or something else.
1302 : *
1303 : * Arguments are a connection object, the cleartext password, the SQL
1304 : * name of the user it is for, and a string indicating the algorithm to
1305 : * use for encrypting the password. If algorithm is NULL, this queries
1306 : * the server for the current 'password_encryption' value. If you wish
1307 : * to avoid that, e.g. to avoid blocking, you can execute
1308 : * 'show password_encryption' yourself before calling this function, and
1309 : * pass it as the algorithm.
1310 : *
1311 : * Return value is a malloc'd string. The client may assume the string
1312 : * doesn't contain any special characters that would require escaping.
1313 : * On error, an error message is stored in the connection object, and
1314 : * returns NULL.
1315 : */
1316 : char *
1317 2 : PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user,
1318 : const char *algorithm)
1319 : {
1320 : #define MAX_ALGORITHM_NAME_LEN 50
1321 : char algobuf[MAX_ALGORITHM_NAME_LEN + 1];
1322 2 : char *crypt_pwd = NULL;
1323 :
1324 2 : if (!conn)
1325 0 : return NULL;
1326 :
1327 2 : pqClearConnErrorState(conn);
1328 :
1329 : /* If no algorithm was given, ask the server. */
1330 2 : if (algorithm == NULL)
1331 : {
1332 : PGresult *res;
1333 : char *val;
1334 :
1335 2 : res = PQexec(conn, "show password_encryption");
1336 2 : if (res == NULL)
1337 : {
1338 : /* PQexec() should've set conn->errorMessage already */
1339 0 : return NULL;
1340 : }
1341 2 : if (PQresultStatus(res) != PGRES_TUPLES_OK)
1342 : {
1343 : /* PQexec() should've set conn->errorMessage already */
1344 0 : PQclear(res);
1345 0 : return NULL;
1346 : }
1347 2 : if (PQntuples(res) != 1 || PQnfields(res) != 1)
1348 : {
1349 0 : PQclear(res);
1350 0 : libpq_append_conn_error(conn, "unexpected shape of result set returned for SHOW");
1351 0 : return NULL;
1352 : }
1353 2 : val = PQgetvalue(res, 0, 0);
1354 :
1355 2 : if (strlen(val) > MAX_ALGORITHM_NAME_LEN)
1356 : {
1357 0 : PQclear(res);
1358 0 : libpq_append_conn_error(conn, "\"password_encryption\" value too long");
1359 0 : return NULL;
1360 : }
1361 2 : strcpy(algobuf, val);
1362 2 : PQclear(res);
1363 :
1364 2 : algorithm = algobuf;
1365 : }
1366 :
1367 : /*
1368 : * Also accept "on" and "off" as aliases for "md5", because
1369 : * password_encryption was a boolean before PostgreSQL 10. We refuse to
1370 : * send the password in plaintext even if it was "off".
1371 : */
1372 2 : if (strcmp(algorithm, "on") == 0 ||
1373 2 : strcmp(algorithm, "off") == 0)
1374 0 : algorithm = "md5";
1375 :
1376 : /*
1377 : * Ok, now we know what algorithm to use
1378 : */
1379 2 : if (strcmp(algorithm, "scram-sha-256") == 0)
1380 : {
1381 2 : const char *errstr = NULL;
1382 :
1383 2 : crypt_pwd = pg_fe_scram_build_secret(passwd,
1384 : conn->scram_sha_256_iterations,
1385 : &errstr);
1386 2 : if (!crypt_pwd)
1387 0 : libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
1388 : }
1389 0 : else if (strcmp(algorithm, "md5") == 0)
1390 : {
1391 0 : crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
1392 0 : if (crypt_pwd)
1393 : {
1394 0 : const char *errstr = NULL;
1395 :
1396 0 : if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd, &errstr))
1397 : {
1398 0 : libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
1399 0 : free(crypt_pwd);
1400 0 : crypt_pwd = NULL;
1401 : }
1402 : }
1403 : else
1404 0 : libpq_append_conn_error(conn, "out of memory");
1405 : }
1406 : else
1407 : {
1408 0 : libpq_append_conn_error(conn, "unrecognized password encryption algorithm \"%s\"",
1409 : algorithm);
1410 0 : return NULL;
1411 : }
1412 :
1413 2 : return crypt_pwd;
1414 : }
1415 :
1416 : /*
1417 : * PQchangePassword -- exported routine to change a password
1418 : *
1419 : * This is intended to be used by client applications that wish to
1420 : * change the password for a user. The password is not sent in
1421 : * cleartext because it is encrypted on the client side. This is
1422 : * good because it ensures the cleartext password is never known by
1423 : * the server, and therefore won't end up in logs, pg_stat displays,
1424 : * etc. The password encryption is performed by PQencryptPasswordConn(),
1425 : * which is passed a NULL for the algorithm argument. Hence encryption
1426 : * is done according to the server's password_encryption
1427 : * setting. We export the function so that clients won't be dependent
1428 : * on the implementation specific details with respect to how the
1429 : * server changes passwords.
1430 : *
1431 : * Arguments are a connection object, the SQL name of the target user,
1432 : * and the cleartext password.
1433 : *
1434 : * Return value is the PGresult of the executed ALTER USER statement
1435 : * or NULL if we never get there. The caller is responsible to PQclear()
1436 : * the returned PGresult.
1437 : *
1438 : * PQresultStatus() should be called to check the return value for errors,
1439 : * and PQerrorMessage() used to get more information about such errors.
1440 : */
1441 : PGresult *
1442 2 : PQchangePassword(PGconn *conn, const char *user, const char *passwd)
1443 : {
1444 2 : char *encrypted_password = PQencryptPasswordConn(conn, passwd,
1445 : user, NULL);
1446 :
1447 2 : if (!encrypted_password)
1448 : {
1449 : /* PQencryptPasswordConn() already registered the error */
1450 0 : return NULL;
1451 : }
1452 : else
1453 : {
1454 2 : char *fmtpw = PQescapeLiteral(conn, encrypted_password,
1455 : strlen(encrypted_password));
1456 :
1457 : /* no longer needed, so clean up now */
1458 2 : PQfreemem(encrypted_password);
1459 :
1460 2 : if (!fmtpw)
1461 : {
1462 : /* PQescapeLiteral() already registered the error */
1463 0 : return NULL;
1464 : }
1465 : else
1466 : {
1467 2 : char *fmtuser = PQescapeIdentifier(conn, user, strlen(user));
1468 :
1469 2 : if (!fmtuser)
1470 : {
1471 : /* PQescapeIdentifier() already registered the error */
1472 0 : PQfreemem(fmtpw);
1473 0 : return NULL;
1474 : }
1475 : else
1476 : {
1477 : PQExpBufferData buf;
1478 : PGresult *res;
1479 :
1480 2 : initPQExpBuffer(&buf);
1481 2 : printfPQExpBuffer(&buf, "ALTER USER %s PASSWORD %s",
1482 : fmtuser, fmtpw);
1483 :
1484 2 : res = PQexec(conn, buf.data);
1485 :
1486 : /* clean up */
1487 2 : termPQExpBuffer(&buf);
1488 2 : PQfreemem(fmtuser);
1489 2 : PQfreemem(fmtpw);
1490 :
1491 2 : return res;
1492 : }
1493 : }
1494 : }
1495 : }
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