Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * fe-secure.c
4 : * functions related to setting up a secure connection to the backend.
5 : * Secure connections are expected to provide confidentiality,
6 : * message integrity and endpoint authentication.
7 : *
8 : *
9 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
10 : * Portions Copyright (c) 1994, Regents of the University of California
11 : *
12 : *
13 : * IDENTIFICATION
14 : * src/interfaces/libpq/fe-secure.c
15 : *
16 : *-------------------------------------------------------------------------
17 : */
18 :
19 : #include "postgres_fe.h"
20 :
21 : #include <signal.h>
22 : #include <fcntl.h>
23 : #include <ctype.h>
24 :
25 : #ifdef WIN32
26 : #include "win32.h"
27 : #else
28 : #include <sys/socket.h>
29 : #include <unistd.h>
30 : #include <netdb.h>
31 : #include <netinet/in.h>
32 : #include <netinet/tcp.h>
33 : #include <arpa/inet.h>
34 : #endif
35 :
36 : #include <sys/stat.h>
37 :
38 : #ifdef WIN32
39 : #include "pthread-win32.h"
40 : #else
41 : #include <pthread.h>
42 : #endif
43 :
44 : #include "fe-auth.h"
45 : #include "libpq-fe.h"
46 : #include "libpq-int.h"
47 :
48 : /*
49 : * Macros to handle disabling and then restoring the state of SIGPIPE handling.
50 : * On Windows, these are all no-ops since there's no SIGPIPEs.
51 : */
52 :
53 : #ifndef WIN32
54 :
55 : #define SIGPIPE_MASKED(conn) ((conn)->sigpipe_so || (conn)->sigpipe_flag)
56 :
57 : struct sigpipe_info
58 : {
59 : sigset_t oldsigmask;
60 : bool sigpipe_pending;
61 : bool got_epipe;
62 : };
63 :
64 : #define DECLARE_SIGPIPE_INFO(spinfo) struct sigpipe_info spinfo
65 :
66 : #define DISABLE_SIGPIPE(conn, spinfo, failaction) \
67 : do { \
68 : (spinfo).got_epipe = false; \
69 : if (!SIGPIPE_MASKED(conn)) \
70 : { \
71 : if (pq_block_sigpipe(&(spinfo).oldsigmask, \
72 : &(spinfo).sigpipe_pending) < 0) \
73 : failaction; \
74 : } \
75 : } while (0)
76 :
77 : #define REMEMBER_EPIPE(spinfo, cond) \
78 : do { \
79 : if (cond) \
80 : (spinfo).got_epipe = true; \
81 : } while (0)
82 :
83 : #define RESTORE_SIGPIPE(conn, spinfo) \
84 : do { \
85 : if (!SIGPIPE_MASKED(conn)) \
86 : pq_reset_sigpipe(&(spinfo).oldsigmask, (spinfo).sigpipe_pending, \
87 : (spinfo).got_epipe); \
88 : } while (0)
89 : #else /* WIN32 */
90 :
91 : #define DECLARE_SIGPIPE_INFO(spinfo)
92 : #define DISABLE_SIGPIPE(conn, spinfo, failaction)
93 : #define REMEMBER_EPIPE(spinfo, cond)
94 : #define RESTORE_SIGPIPE(conn, spinfo)
95 : #endif /* WIN32 */
96 :
97 : /* ------------------------------------------------------------ */
98 : /* Procedures common to all secure sessions */
99 : /* ------------------------------------------------------------ */
100 :
101 :
102 : int
103 4 : PQsslInUse(PGconn *conn)
104 : {
105 4 : if (!conn)
106 0 : return 0;
107 4 : return conn->ssl_in_use;
108 : }
109 :
110 : /*
111 : * Exported function to allow application to tell us it's already
112 : * initialized OpenSSL.
113 : */
114 : void
115 0 : PQinitSSL(int do_init)
116 : {
117 : #ifdef USE_SSL
118 0 : pgtls_init_library(do_init, do_init);
119 : #endif
120 0 : }
121 :
122 : /*
123 : * Exported function to allow application to tell us it's already
124 : * initialized OpenSSL and/or libcrypto.
125 : */
126 : void
127 0 : PQinitOpenSSL(int do_ssl, int do_crypto)
128 : {
129 : #ifdef USE_SSL
130 0 : pgtls_init_library(do_ssl, do_crypto);
131 : #endif
132 0 : }
133 :
134 : /*
135 : * Initialize global SSL context
136 : */
137 : int
138 23006 : pqsecure_initialize(PGconn *conn, bool do_ssl, bool do_crypto)
139 : {
140 23006 : int r = 0;
141 :
142 : #ifdef USE_SSL
143 23006 : r = pgtls_init(conn, do_ssl, do_crypto);
144 : #endif
145 :
146 23006 : return r;
147 : }
148 :
149 : /*
150 : * Begin or continue negotiating a secure session.
151 : */
152 : PostgresPollingStatusType
153 680 : pqsecure_open_client(PGconn *conn)
154 : {
155 : #ifdef USE_SSL
156 680 : return pgtls_open_client(conn);
157 : #else
158 : /* shouldn't get here */
159 : return PGRES_POLLING_FAILED;
160 : #endif
161 : }
162 :
163 : /*
164 : * Close secure session.
165 : */
166 : void
167 45198 : pqsecure_close(PGconn *conn)
168 : {
169 : #ifdef USE_SSL
170 45198 : pgtls_close(conn);
171 : #endif
172 45198 : }
173 :
174 : /*
175 : * Read data from a secure connection.
176 : *
177 : * On failure, this function is responsible for appending a suitable message
178 : * to conn->errorMessage. The caller must still inspect errno, but only
179 : * to determine whether to continue/retry after error.
180 : */
181 : ssize_t
182 1662678 : pqsecure_read(PGconn *conn, void *ptr, size_t len)
183 : {
184 : ssize_t n;
185 :
186 : #ifdef USE_SSL
187 1662678 : if (conn->ssl_in_use)
188 : {
189 792 : n = pgtls_read(conn, ptr, len);
190 : }
191 : else
192 : #endif
193 : #ifdef ENABLE_GSS
194 : if (conn->gssenc)
195 : {
196 : n = pg_GSS_read(conn, ptr, len);
197 : }
198 : else
199 : #endif
200 : {
201 1661886 : n = pqsecure_raw_read(conn, ptr, len);
202 : }
203 :
204 1662678 : return n;
205 : }
206 :
207 : ssize_t
208 1667648 : pqsecure_raw_read(PGconn *conn, void *ptr, size_t len)
209 : {
210 : ssize_t n;
211 1667648 : int result_errno = 0;
212 : char sebuf[PG_STRERROR_R_BUFLEN];
213 :
214 1667648 : SOCK_ERRNO_SET(0);
215 :
216 1667648 : n = recv(conn->sock, ptr, len, 0);
217 :
218 1667648 : if (n < 0)
219 : {
220 554076 : result_errno = SOCK_ERRNO;
221 :
222 : /* Set error message if appropriate */
223 554076 : switch (result_errno)
224 : {
225 : #ifdef EAGAIN
226 554074 : case EAGAIN:
227 : #endif
228 : #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
229 : case EWOULDBLOCK:
230 : #endif
231 : case EINTR:
232 : /* no error message, caller is expected to retry */
233 554074 : break;
234 :
235 2 : case EPIPE:
236 : case ECONNRESET:
237 2 : libpq_append_conn_error(conn, "server closed the connection unexpectedly\n"
238 : "\tThis probably means the server terminated abnormally\n"
239 : "\tbefore or while processing the request.");
240 2 : break;
241 :
242 0 : case 0:
243 : /* If errno didn't get set, treat it as regular EOF */
244 0 : n = 0;
245 0 : break;
246 :
247 0 : default:
248 0 : libpq_append_conn_error(conn, "could not receive data from server: %s",
249 : SOCK_STRERROR(result_errno,
250 : sebuf, sizeof(sebuf)));
251 0 : break;
252 : }
253 1113572 : }
254 :
255 : /* ensure we return the intended errno to caller */
256 1667648 : SOCK_ERRNO_SET(result_errno);
257 :
258 1667648 : return n;
259 : }
260 :
261 : /*
262 : * Write data to a secure connection.
263 : *
264 : * Returns the number of bytes written, or a negative value (with errno
265 : * set) upon failure. The write count could be less than requested.
266 : *
267 : * Note that socket-level hard failures are masked from the caller,
268 : * instead setting conn->write_failed and storing an error message
269 : * in conn->write_err_msg; see pqsecure_raw_write. This allows us to
270 : * postpone reporting of write failures until we're sure no error
271 : * message is available from the server.
272 : *
273 : * However, errors detected in the SSL or GSS management level are reported
274 : * via a negative result, with message appended to conn->errorMessage.
275 : * It's frequently unclear whether such errors should be considered read or
276 : * write errors, so we don't attempt to postpone reporting them.
277 : *
278 : * The caller must still inspect errno upon failure, but only to determine
279 : * whether to continue/retry; a message has been saved someplace in any case.
280 : */
281 : ssize_t
282 770642 : pqsecure_write(PGconn *conn, const void *ptr, size_t len)
283 : {
284 : ssize_t n;
285 :
286 : #ifdef USE_SSL
287 770642 : if (conn->ssl_in_use)
288 : {
289 512 : n = pgtls_write(conn, ptr, len);
290 : }
291 : else
292 : #endif
293 : #ifdef ENABLE_GSS
294 : if (conn->gssenc)
295 : {
296 : n = pg_GSS_write(conn, ptr, len);
297 : }
298 : else
299 : #endif
300 : {
301 770130 : n = pqsecure_raw_write(conn, ptr, len);
302 : }
303 :
304 770642 : return n;
305 : }
306 :
307 : /*
308 : * Low-level implementation of pqsecure_write.
309 : *
310 : * This is used directly for an unencrypted connection. For encrypted
311 : * connections, this does the physical I/O on behalf of pgtls_write or
312 : * pg_GSS_write.
313 : *
314 : * This function reports failure (i.e., returns a negative result) only
315 : * for retryable errors such as EINTR. Looping for such cases is to be
316 : * handled at some outer level, maybe all the way up to the application.
317 : * For hard failures, we set conn->write_failed and store an error message
318 : * in conn->write_err_msg, but then claim to have written the data anyway.
319 : * This is because we don't want to report write failures so long as there
320 : * is a possibility of reading from the server and getting an error message
321 : * that could explain why the connection dropped. Many TCP stacks have
322 : * race conditions such that a write failure may or may not be reported
323 : * before all incoming data has been read.
324 : *
325 : * Note that this error behavior happens below the SSL management level when
326 : * we are using SSL. That's because at least some versions of OpenSSL are
327 : * too quick to report a write failure when there's still a possibility to
328 : * get a more useful error from the server.
329 : */
330 : ssize_t
331 771504 : pqsecure_raw_write(PGconn *conn, const void *ptr, size_t len)
332 : {
333 : ssize_t n;
334 771504 : int flags = 0;
335 771504 : int result_errno = 0;
336 : char msgbuf[1024];
337 : char sebuf[PG_STRERROR_R_BUFLEN];
338 :
339 : DECLARE_SIGPIPE_INFO(spinfo);
340 :
341 : /*
342 : * If we already had a write failure, we will never again try to send data
343 : * on that connection. Even if the kernel would let us, we've probably
344 : * lost message boundary sync with the server. conn->write_failed
345 : * therefore persists until the connection is reset, and we just discard
346 : * all data presented to be written.
347 : */
348 771504 : if (conn->write_failed)
349 0 : return len;
350 :
351 : #ifdef MSG_NOSIGNAL
352 771504 : if (conn->sigpipe_flag)
353 771504 : flags |= MSG_NOSIGNAL;
354 :
355 771504 : retry_masked:
356 : #endif /* MSG_NOSIGNAL */
357 :
358 771504 : DISABLE_SIGPIPE(conn, spinfo, return -1);
359 :
360 771504 : n = send(conn->sock, ptr, len, flags);
361 :
362 771504 : if (n < 0)
363 : {
364 68 : result_errno = SOCK_ERRNO;
365 :
366 : /*
367 : * If we see an EINVAL, it may be because MSG_NOSIGNAL isn't available
368 : * on this machine. So, clear sigpipe_flag so we don't try the flag
369 : * again, and retry the send().
370 : */
371 : #ifdef MSG_NOSIGNAL
372 68 : if (flags != 0 && result_errno == EINVAL)
373 : {
374 0 : conn->sigpipe_flag = false;
375 0 : flags = 0;
376 0 : goto retry_masked;
377 : }
378 : #endif /* MSG_NOSIGNAL */
379 :
380 : /* Set error message if appropriate */
381 68 : switch (result_errno)
382 : {
383 : #ifdef EAGAIN
384 42 : case EAGAIN:
385 : #endif
386 : #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
387 : case EWOULDBLOCK:
388 : #endif
389 : case EINTR:
390 : /* no error message, caller is expected to retry */
391 42 : break;
392 :
393 26 : case EPIPE:
394 : /* Set flag for EPIPE */
395 26 : REMEMBER_EPIPE(spinfo, true);
396 :
397 : /* FALL THRU */
398 :
399 : case ECONNRESET:
400 26 : conn->write_failed = true;
401 : /* Store error message in conn->write_err_msg, if possible */
402 : /* (strdup failure is OK, we'll cope later) */
403 26 : snprintf(msgbuf, sizeof(msgbuf),
404 26 : libpq_gettext("server closed the connection unexpectedly\n"
405 : "\tThis probably means the server terminated abnormally\n"
406 : "\tbefore or while processing the request."));
407 : /* keep newline out of translated string */
408 26 : strlcat(msgbuf, "\n", sizeof(msgbuf));
409 26 : conn->write_err_msg = strdup(msgbuf);
410 : /* Now claim the write succeeded */
411 26 : n = len;
412 26 : break;
413 :
414 0 : default:
415 0 : conn->write_failed = true;
416 : /* Store error message in conn->write_err_msg, if possible */
417 : /* (strdup failure is OK, we'll cope later) */
418 0 : snprintf(msgbuf, sizeof(msgbuf),
419 0 : libpq_gettext("could not send data to server: %s"),
420 : SOCK_STRERROR(result_errno,
421 : sebuf, sizeof(sebuf)));
422 : /* keep newline out of translated string */
423 0 : strlcat(msgbuf, "\n", sizeof(msgbuf));
424 0 : conn->write_err_msg = strdup(msgbuf);
425 : /* Now claim the write succeeded */
426 0 : n = len;
427 0 : break;
428 : }
429 771436 : }
430 :
431 771504 : RESTORE_SIGPIPE(conn, spinfo);
432 :
433 : /* ensure we return the intended errno to caller */
434 771504 : SOCK_ERRNO_SET(result_errno);
435 :
436 771504 : return n;
437 : }
438 :
439 : /* Dummy versions of SSL info functions, when built without SSL support */
440 : #ifndef USE_SSL
441 :
442 : void *
443 : PQgetssl(PGconn *conn)
444 : {
445 : return NULL;
446 : }
447 :
448 : void *
449 : PQsslStruct(PGconn *conn, const char *struct_name)
450 : {
451 : return NULL;
452 : }
453 :
454 : const char *
455 : PQsslAttribute(PGconn *conn, const char *attribute_name)
456 : {
457 : return NULL;
458 : }
459 :
460 : const char *const *
461 : PQsslAttributeNames(PGconn *conn)
462 : {
463 : static const char *const result[] = {NULL};
464 :
465 : return result;
466 : }
467 : #endif /* USE_SSL */
468 :
469 : /*
470 : * Dummy versions of OpenSSL key password hook functions, when built without
471 : * OpenSSL.
472 : */
473 : #ifndef USE_OPENSSL
474 :
475 : PQsslKeyPassHook_OpenSSL_type
476 : PQgetSSLKeyPassHook_OpenSSL(void)
477 : {
478 : return NULL;
479 : }
480 :
481 : void
482 : PQsetSSLKeyPassHook_OpenSSL(PQsslKeyPassHook_OpenSSL_type hook)
483 : {
484 : return;
485 : }
486 :
487 : int
488 : PQdefaultSSLKeyPassHook_OpenSSL(char *buf, int size, PGconn *conn)
489 : {
490 : return 0;
491 : }
492 : #endif /* USE_OPENSSL */
493 :
494 : /* Dummy version of GSSAPI information functions, when built without GSS support */
495 : #ifndef ENABLE_GSS
496 :
497 : void *
498 0 : PQgetgssctx(PGconn *conn)
499 : {
500 0 : return NULL;
501 : }
502 :
503 : int
504 4 : PQgssEncInUse(PGconn *conn)
505 : {
506 4 : return 0;
507 : }
508 :
509 : #endif /* ENABLE_GSS */
510 :
511 :
512 : #if !defined(WIN32)
513 :
514 : /*
515 : * Block SIGPIPE for this thread. This prevents send()/write() from exiting
516 : * the application.
517 : */
518 : int
519 0 : pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending)
520 : {
521 : sigset_t sigpipe_sigset;
522 : sigset_t sigset;
523 :
524 0 : sigemptyset(&sigpipe_sigset);
525 0 : sigaddset(&sigpipe_sigset, SIGPIPE);
526 :
527 : /* Block SIGPIPE and save previous mask for later reset */
528 0 : SOCK_ERRNO_SET(pthread_sigmask(SIG_BLOCK, &sigpipe_sigset, osigset));
529 0 : if (SOCK_ERRNO)
530 0 : return -1;
531 :
532 : /* We can have a pending SIGPIPE only if it was blocked before */
533 0 : if (sigismember(osigset, SIGPIPE))
534 : {
535 : /* Is there a pending SIGPIPE? */
536 0 : if (sigpending(&sigset) != 0)
537 0 : return -1;
538 :
539 0 : if (sigismember(&sigset, SIGPIPE))
540 0 : *sigpipe_pending = true;
541 : else
542 0 : *sigpipe_pending = false;
543 : }
544 : else
545 0 : *sigpipe_pending = false;
546 :
547 0 : return 0;
548 : }
549 :
550 : /*
551 : * Discard any pending SIGPIPE and reset the signal mask.
552 : *
553 : * Note: we are effectively assuming here that the C library doesn't queue
554 : * up multiple SIGPIPE events. If it did, then we'd accidentally leave
555 : * ours in the queue when an event was already pending and we got another.
556 : * As long as it doesn't queue multiple events, we're OK because the caller
557 : * can't tell the difference.
558 : *
559 : * The caller should say got_epipe = false if it is certain that it
560 : * didn't get an EPIPE error; in that case we'll skip the clear operation
561 : * and things are definitely OK, queuing or no. If it got one or might have
562 : * gotten one, pass got_epipe = true.
563 : *
564 : * We do not want this to change errno, since if it did that could lose
565 : * the error code from a preceding send(). We essentially assume that if
566 : * we were able to do pq_block_sigpipe(), this can't fail.
567 : */
568 : void
569 0 : pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending, bool got_epipe)
570 : {
571 0 : int save_errno = SOCK_ERRNO;
572 : int signo;
573 : sigset_t sigset;
574 :
575 : /* Clear SIGPIPE only if none was pending */
576 0 : if (got_epipe && !sigpipe_pending)
577 : {
578 0 : if (sigpending(&sigset) == 0 &&
579 0 : sigismember(&sigset, SIGPIPE))
580 : {
581 : sigset_t sigpipe_sigset;
582 :
583 0 : sigemptyset(&sigpipe_sigset);
584 0 : sigaddset(&sigpipe_sigset, SIGPIPE);
585 :
586 0 : sigwait(&sigpipe_sigset, &signo);
587 : }
588 : }
589 :
590 : /* Restore saved block mask */
591 0 : pthread_sigmask(SIG_SETMASK, osigset, NULL);
592 :
593 0 : SOCK_ERRNO_SET(save_errno);
594 0 : }
595 :
596 : #endif /* !WIN32 */
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