Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * backend_startup.c
4 : * Backend startup code
5 : *
6 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/tcop/backend_startup.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 :
16 : #include "postgres.h"
17 :
18 : #include <unistd.h>
19 :
20 : #include "access/xlog.h"
21 : #include "access/xlogrecovery.h"
22 : #include "common/ip.h"
23 : #include "common/string.h"
24 : #include "libpq/libpq.h"
25 : #include "libpq/libpq-be.h"
26 : #include "libpq/pqformat.h"
27 : #include "libpq/pqsignal.h"
28 : #include "miscadmin.h"
29 : #include "postmaster/postmaster.h"
30 : #include "replication/walsender.h"
31 : #include "storage/fd.h"
32 : #include "storage/ipc.h"
33 : #include "storage/procsignal.h"
34 : #include "storage/proc.h"
35 : #include "tcop/backend_startup.h"
36 : #include "tcop/tcopprot.h"
37 : #include "utils/builtins.h"
38 : #include "utils/guc_hooks.h"
39 : #include "utils/injection_point.h"
40 : #include "utils/memutils.h"
41 : #include "utils/ps_status.h"
42 : #include "utils/timeout.h"
43 : #include "utils/varlena.h"
44 :
45 : /* GUCs */
46 : bool Trace_connection_negotiation = false;
47 : uint32 log_connections = 0;
48 : char *log_connections_string = NULL;
49 :
50 : /* Other globals */
51 :
52 : /*
53 : * ConnectionTiming stores timestamps of various points in connection
54 : * establishment and setup.
55 : * ready_for_use is initialized to a special value here so we can check if
56 : * we've already set it before doing so in PostgresMain().
57 : */
58 : ConnectionTiming conn_timing = {.ready_for_use = TIMESTAMP_MINUS_INFINITY};
59 :
60 : static void BackendInitialize(ClientSocket *client_sock, CAC_state cac);
61 : static int ProcessSSLStartup(Port *port);
62 : static int ProcessStartupPacket(Port *port);
63 : static void ProcessCancelRequestPacket(Port *port, void *pkt, int pktlen);
64 : static void SendNegotiateProtocolVersion(List *unrecognized_protocol_options);
65 : static void process_startup_packet_die(SIGNAL_ARGS);
66 : static void StartupPacketTimeoutHandler(void);
67 : static bool validate_log_connections_options(List *elemlist, uint32 *flags);
68 :
69 : /*
70 : * Entry point for a new backend process.
71 : *
72 : * Initialize the connection, read the startup packet, authenticate the
73 : * client, and start the main processing loop.
74 : */
75 : void
76 15124 : BackendMain(const void *startup_data, size_t startup_data_len)
77 : {
78 15124 : const BackendStartupData *bsdata = startup_data;
79 :
80 : Assert(startup_data_len == sizeof(BackendStartupData));
81 : Assert(MyClientSocket != NULL);
82 :
83 : #ifdef EXEC_BACKEND
84 :
85 : /*
86 : * Need to reinitialize the SSL library in the backend, since the context
87 : * structures contain function pointers and cannot be passed through the
88 : * parameter file.
89 : *
90 : * If for some reason reload fails (maybe the user installed broken key
91 : * files), soldier on without SSL; that's better than all connections
92 : * becoming impossible.
93 : *
94 : * XXX should we do this in all child processes? For the moment it's
95 : * enough to do it in backend children.
96 : */
97 : #ifdef USE_SSL
98 : if (EnableSSL)
99 : {
100 : if (secure_initialize(false) == 0)
101 : LoadedSSL = true;
102 : else
103 : ereport(LOG,
104 : (errmsg("SSL configuration could not be loaded in child process")));
105 : }
106 : #endif
107 : #endif
108 :
109 : /* Perform additional initialization and collect startup packet */
110 15124 : BackendInitialize(MyClientSocket, bsdata->canAcceptConnections);
111 :
112 : /*
113 : * Create a per-backend PGPROC struct in shared memory. We must do this
114 : * before we can use LWLocks or access any shared memory.
115 : */
116 14829 : InitProcess();
117 :
118 : /*
119 : * Make sure we aren't in PostmasterContext anymore. (We can't delete it
120 : * just yet, though, because InitPostgres will need the HBA data.)
121 : */
122 14826 : MemoryContextSwitchTo(TopMemoryContext);
123 :
124 14826 : PostgresMain(MyProcPort->database_name, MyProcPort->user_name);
125 : }
126 :
127 :
128 : /*
129 : * BackendInitialize -- initialize an interactive (postmaster-child)
130 : * backend process, and collect the client's startup packet.
131 : *
132 : * returns: nothing. Will not return at all if there's any failure.
133 : *
134 : * Note: this code does not depend on having any access to shared memory.
135 : * Indeed, our approach to SIGTERM/timeout handling *requires* that
136 : * shared memory not have been touched yet; see comments within.
137 : * In the EXEC_BACKEND case, we are physically attached to shared memory
138 : * but have not yet set up most of our local pointers to shmem structures.
139 : */
140 : static void
141 15124 : BackendInitialize(ClientSocket *client_sock, CAC_state cac)
142 : {
143 : int status;
144 : int ret;
145 : Port *port;
146 : char remote_host[NI_MAXHOST];
147 : char remote_port[NI_MAXSERV];
148 : StringInfoData ps_data;
149 : MemoryContext oldcontext;
150 :
151 : /* Tell fd.c about the long-lived FD associated with the client_sock */
152 15124 : ReserveExternalFD();
153 :
154 : /*
155 : * PreAuthDelay is a debugging aid for investigating problems in the
156 : * authentication cycle: it can be set in postgresql.conf to allow time to
157 : * attach to the newly-forked backend with a debugger. (See also
158 : * PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it
159 : * is not honored until after authentication.)
160 : */
161 15124 : if (PreAuthDelay > 0)
162 0 : pg_usleep(PreAuthDelay * 1000000L);
163 :
164 : /* This flag will remain set until InitPostgres finishes authentication */
165 15124 : ClientAuthInProgress = true; /* limit visibility of log messages */
166 :
167 : /*
168 : * Initialize libpq and enable reporting of ereport errors to the client.
169 : * Must do this now because authentication uses libpq to send messages.
170 : *
171 : * The Port structure and all data structures attached to it are allocated
172 : * in TopMemoryContext, so that they survive into PostgresMain execution.
173 : * We need not worry about leaking this storage on failure, since we
174 : * aren't in the postmaster process anymore.
175 : */
176 15124 : oldcontext = MemoryContextSwitchTo(TopMemoryContext);
177 15124 : port = MyProcPort = pq_init(client_sock);
178 15124 : MemoryContextSwitchTo(oldcontext);
179 :
180 15124 : whereToSendOutput = DestRemote; /* now safe to ereport to client */
181 :
182 : /* set these to empty in case they are needed before we set them up */
183 15124 : port->remote_host = "";
184 15124 : port->remote_port = "";
185 :
186 : /*
187 : * We arrange to do _exit(1) if we receive SIGTERM or timeout while trying
188 : * to collect the startup packet; while SIGQUIT results in _exit(2).
189 : * Otherwise the postmaster cannot shutdown the database FAST or IMMED
190 : * cleanly if a buggy client fails to send the packet promptly.
191 : *
192 : * Exiting with _exit(1) is only possible because we have not yet touched
193 : * shared memory; therefore no outside-the-process state needs to get
194 : * cleaned up.
195 : */
196 15124 : pqsignal(SIGTERM, process_startup_packet_die);
197 : /* SIGQUIT handler was already set up by InitPostmasterChild */
198 15124 : InitializeTimeouts(); /* establishes SIGALRM handler */
199 15124 : sigprocmask(SIG_SETMASK, &StartupBlockSig, NULL);
200 :
201 : /*
202 : * Get the remote host name and port for logging and status display.
203 : */
204 15124 : remote_host[0] = '\0';
205 15124 : remote_port[0] = '\0';
206 15124 : if ((ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
207 : remote_host, sizeof(remote_host),
208 : remote_port, sizeof(remote_port),
209 : (log_hostname ? 0 : NI_NUMERICHOST) | NI_NUMERICSERV)) != 0)
210 0 : ereport(WARNING,
211 : (errmsg_internal("pg_getnameinfo_all() failed: %s",
212 : gai_strerror(ret))));
213 :
214 : /*
215 : * Save remote_host and remote_port in port structure (after this, they
216 : * will appear in log_line_prefix data for log messages).
217 : */
218 15124 : port->remote_host = MemoryContextStrdup(TopMemoryContext, remote_host);
219 15124 : port->remote_port = MemoryContextStrdup(TopMemoryContext, remote_port);
220 :
221 : /* And now we can log that the connection was received, if enabled */
222 15124 : if (log_connections & LOG_CONNECTION_RECEIPT)
223 : {
224 447 : if (remote_port[0])
225 190 : ereport(LOG,
226 : (errmsg("connection received: host=%s port=%s",
227 : remote_host,
228 : remote_port)));
229 : else
230 257 : ereport(LOG,
231 : (errmsg("connection received: host=%s",
232 : remote_host)));
233 : }
234 :
235 : /* For testing client error handling */
236 : #ifdef USE_INJECTION_POINTS
237 15124 : INJECTION_POINT("backend-initialize", NULL);
238 15124 : if (IS_INJECTION_POINT_ATTACHED("backend-initialize-v2-error"))
239 : {
240 : /*
241 : * This simulates an early error from a pre-v14 server, which used the
242 : * version 2 protocol for any errors that occurred before processing
243 : * the startup packet.
244 : */
245 1 : FrontendProtocol = PG_PROTOCOL(2, 0);
246 1 : elog(FATAL, "protocol version 2 error triggered");
247 : }
248 : #endif
249 :
250 : /*
251 : * If we did a reverse lookup to name, we might as well save the results
252 : * rather than possibly repeating the lookup during authentication.
253 : *
254 : * Note that we don't want to specify NI_NAMEREQD above, because then we'd
255 : * get nothing useful for a client without an rDNS entry. Therefore, we
256 : * must check whether we got a numeric IPv4 or IPv6 address, and not save
257 : * it into remote_hostname if so. (This test is conservative and might
258 : * sometimes classify a hostname as numeric, but an error in that
259 : * direction is safe; it only results in a possible extra lookup.)
260 : */
261 15123 : if (log_hostname &&
262 160 : ret == 0 &&
263 160 : strspn(remote_host, "0123456789.") < strlen(remote_host) &&
264 160 : strspn(remote_host, "0123456789ABCDEFabcdef:") < strlen(remote_host))
265 : {
266 160 : port->remote_hostname = MemoryContextStrdup(TopMemoryContext, remote_host);
267 : }
268 :
269 : /*
270 : * Ready to begin client interaction. We will give up and _exit(1) after
271 : * a time delay, so that a broken client can't hog a connection
272 : * indefinitely. PreAuthDelay and any DNS interactions above don't count
273 : * against the time limit.
274 : *
275 : * Note: AuthenticationTimeout is applied here while waiting for the
276 : * startup packet, and then again in InitPostgres for the duration of any
277 : * authentication operations. So a hostile client could tie up the
278 : * process for nearly twice AuthenticationTimeout before we kick him off.
279 : *
280 : * Note: because PostgresMain will call InitializeTimeouts again, the
281 : * registration of STARTUP_PACKET_TIMEOUT will be lost. This is okay
282 : * since we never use it again after this function.
283 : */
284 15123 : RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler);
285 15123 : enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000);
286 :
287 : /* Handle direct SSL handshake */
288 15123 : status = ProcessSSLStartup(port);
289 :
290 : /*
291 : * Receive the startup packet (which might turn out to be a cancel request
292 : * packet).
293 : */
294 15123 : if (status == STATUS_OK)
295 15119 : status = ProcessStartupPacket(port);
296 :
297 : /*
298 : * If we're going to reject the connection due to database state, say so
299 : * now instead of wasting cycles on an authentication exchange. (This also
300 : * allows a pg_ping utility to be written.)
301 : */
302 15121 : if (status == STATUS_OK)
303 : {
304 15054 : switch (cac)
305 : {
306 172 : case CAC_STARTUP:
307 172 : ereport(FATAL,
308 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
309 : errmsg("the database system is starting up")));
310 : break;
311 3 : case CAC_NOTHOTSTANDBY:
312 3 : if (!EnableHotStandby)
313 0 : ereport(FATAL,
314 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
315 : errmsg("the database system is not accepting connections"),
316 : errdetail("Hot standby mode is disabled.")));
317 3 : else if (reachedConsistency)
318 0 : ereport(FATAL,
319 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
320 : errmsg("the database system is not yet accepting connections"),
321 : errdetail("Recovery snapshot is not yet ready for hot standby."),
322 : errhint("To enable hot standby, close write transactions with more than %d subtransactions on the primary server.",
323 : PGPROC_MAX_CACHED_SUBXIDS)));
324 : else
325 3 : ereport(FATAL,
326 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
327 : errmsg("the database system is not yet accepting connections"),
328 : errdetail("Consistent recovery state has not been yet reached.")));
329 : break;
330 47 : case CAC_SHUTDOWN:
331 47 : ereport(FATAL,
332 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
333 : errmsg("the database system is shutting down")));
334 : break;
335 2 : case CAC_RECOVERY:
336 2 : ereport(FATAL,
337 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
338 : errmsg("the database system is in recovery mode")));
339 : break;
340 1 : case CAC_TOOMANY:
341 1 : ereport(FATAL,
342 : (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
343 : errmsg("sorry, too many clients already")));
344 : break;
345 14829 : case CAC_OK:
346 14829 : break;
347 : }
348 : }
349 :
350 : /*
351 : * Disable the timeout, and prevent SIGTERM again.
352 : */
353 14896 : disable_timeout(STARTUP_PACKET_TIMEOUT, false);
354 14896 : sigprocmask(SIG_SETMASK, &BlockSig, NULL);
355 :
356 : /*
357 : * As a safety check that nothing in startup has yet performed
358 : * shared-memory modifications that would need to be undone if we had
359 : * exited through SIGTERM or timeout above, check that no on_shmem_exit
360 : * handlers have been registered yet. (This isn't terribly bulletproof,
361 : * since someone might misuse an on_proc_exit handler for shmem cleanup,
362 : * but it's a cheap and helpful check. We cannot disallow on_proc_exit
363 : * handlers unfortunately, since pq_init() already registered one.)
364 : */
365 14896 : check_on_shmem_exit_lists_are_empty();
366 :
367 : /*
368 : * Stop here if it was bad or a cancel packet. ProcessStartupPacket
369 : * already did any appropriate error reporting.
370 : */
371 14896 : if (status != STATUS_OK)
372 67 : proc_exit(0);
373 :
374 : /*
375 : * Now that we have the user and database name, we can set the process
376 : * title for ps. It's good to do this as early as possible in startup.
377 : */
378 14829 : initStringInfo(&ps_data);
379 14829 : if (am_walsender)
380 1314 : appendStringInfo(&ps_data, "%s ", GetBackendTypeDesc(B_WAL_SENDER));
381 14829 : appendStringInfo(&ps_data, "%s ", port->user_name);
382 14829 : if (port->database_name[0] != '\0')
383 14325 : appendStringInfo(&ps_data, "%s ", port->database_name);
384 14829 : appendStringInfoString(&ps_data, port->remote_host);
385 14829 : if (port->remote_port[0] != '\0')
386 284 : appendStringInfo(&ps_data, "(%s)", port->remote_port);
387 :
388 14829 : init_ps_display(ps_data.data);
389 14829 : pfree(ps_data.data);
390 :
391 14829 : set_ps_display("initializing");
392 14829 : }
393 :
394 : /*
395 : * Check for a direct SSL connection.
396 : *
397 : * This happens before the startup packet so we are careful not to actually
398 : * read any bytes from the stream if it's not a direct SSL connection.
399 : */
400 : static int
401 15123 : ProcessSSLStartup(Port *port)
402 : {
403 : int firstbyte;
404 :
405 : Assert(!port->ssl_in_use);
406 :
407 15123 : pq_startmsgread();
408 15123 : firstbyte = pq_peekbyte();
409 15123 : pq_endmsgread();
410 15123 : if (firstbyte == EOF)
411 : {
412 : /*
413 : * Like in ProcessStartupPacket, if we get no data at all, don't
414 : * clutter the log with a complaint.
415 : */
416 2 : return STATUS_ERROR;
417 : }
418 :
419 15121 : if (firstbyte != 0x16)
420 : {
421 : /* Not an SSL handshake message */
422 15116 : return STATUS_OK;
423 : }
424 :
425 : /*
426 : * First byte indicates standard SSL handshake message
427 : *
428 : * (It can't be a Postgres startup length because in network byte order
429 : * that would be a startup packet hundreds of megabytes long)
430 : */
431 :
432 : #ifdef USE_SSL
433 5 : if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX)
434 : {
435 : /* SSL not supported */
436 2 : goto reject;
437 : }
438 :
439 3 : if (secure_open_server(port) == -1)
440 : {
441 : /*
442 : * we assume secure_open_server() sent an appropriate TLS alert
443 : * already
444 : */
445 0 : goto reject;
446 : }
447 : Assert(port->ssl_in_use);
448 :
449 3 : if (!port->alpn_used)
450 : {
451 0 : ereport(COMMERROR,
452 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
453 : errmsg("received direct SSL connection request without ALPN protocol negotiation extension")));
454 0 : goto reject;
455 : }
456 :
457 3 : if (Trace_connection_negotiation)
458 3 : ereport(LOG,
459 : (errmsg("direct SSL connection accepted")));
460 3 : return STATUS_OK;
461 : #else
462 : /* SSL not supported by this build */
463 : goto reject;
464 : #endif
465 :
466 2 : reject:
467 2 : if (Trace_connection_negotiation)
468 2 : ereport(LOG,
469 : (errmsg("direct SSL connection rejected")));
470 2 : return STATUS_ERROR;
471 : }
472 :
473 : /*
474 : * Read a client's startup packet and do something according to it.
475 : *
476 : * Returns STATUS_OK or STATUS_ERROR, or might call ereport(FATAL) and
477 : * not return at all.
478 : *
479 : * (Note that ereport(FATAL) stuff is sent to the client, so only use it
480 : * if that's what you want. Return STATUS_ERROR if you don't want to
481 : * send anything to the client, which would typically be appropriate
482 : * if we detect a communications failure.)
483 : *
484 : */
485 : static int
486 15119 : ProcessStartupPacket(Port *port)
487 : {
488 : int32 len;
489 15119 : char *buf = NULL;
490 : ProtocolVersion proto;
491 : MemoryContext oldcontext;
492 : bool gss_done;
493 : bool ssl_done;
494 :
495 : /*
496 : * Set ssl_done and/or gss_done when negotiation of an encrypted layer
497 : * (currently, TLS or GSSAPI) is completed. A successful negotiation of
498 : * either encryption layer sets both flags, but a rejected negotiation
499 : * sets only the flag for that layer, since the client may wish to try the
500 : * other one. We should make no assumption here about the order in which
501 : * the client may make requests.
502 : */
503 15119 : gss_done = false;
504 15119 : ssl_done = false;
505 :
506 287 : retry:
507 15406 : pq_startmsgread();
508 :
509 : /*
510 : * Grab the first byte of the length word separately, so that we can tell
511 : * whether we have no data at all or an incomplete packet. (This might
512 : * sound inefficient, but it's not really, because of buffering in
513 : * pqcomm.c.)
514 : */
515 15406 : if (pq_getbytes(&len, 1) == EOF)
516 : {
517 : /*
518 : * If we get no data at all, don't clutter the log with a complaint;
519 : * such cases often occur for legitimate reasons. An example is that
520 : * we might be here after responding to NEGOTIATE_SSL_CODE, and if the
521 : * client didn't like our response, it'll probably just drop the
522 : * connection. Service-monitoring software also often just opens and
523 : * closes a connection without sending anything. (So do port
524 : * scanners, which may be less benign, but it's not really our job to
525 : * notice those.)
526 : */
527 16 : goto fail;
528 : }
529 :
530 15390 : if (pq_getbytes(((char *) &len) + 1, 3) == EOF)
531 : {
532 : /* Got a partial length word, so bleat about that */
533 0 : if (!ssl_done && !gss_done)
534 0 : ereport(COMMERROR,
535 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
536 : errmsg("incomplete startup packet")));
537 0 : goto fail;
538 : }
539 :
540 15390 : len = pg_ntoh32(len);
541 15390 : len -= 4;
542 :
543 15390 : if (len < (int32) sizeof(ProtocolVersion) ||
544 15390 : len > MAX_STARTUP_PACKET_LENGTH)
545 : {
546 0 : ereport(COMMERROR,
547 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
548 : errmsg("invalid length of startup packet")));
549 0 : goto fail;
550 : }
551 :
552 : /*
553 : * Allocate space to hold the startup packet, plus one extra byte that's
554 : * initialized to be zero. This ensures we will have null termination of
555 : * all strings inside the packet.
556 : */
557 15390 : buf = palloc(len + 1);
558 15390 : buf[len] = '\0';
559 :
560 15390 : if (pq_getbytes(buf, len) == EOF)
561 : {
562 0 : ereport(COMMERROR,
563 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
564 : errmsg("incomplete startup packet")));
565 0 : goto fail;
566 : }
567 15390 : pq_endmsgread();
568 :
569 : /*
570 : * The first field is either a protocol version number or a special
571 : * request code.
572 : */
573 15390 : port->proto = proto = pg_ntoh32(*((ProtocolVersion *) buf));
574 :
575 15390 : if (proto == CANCEL_REQUEST_CODE)
576 : {
577 15 : ProcessCancelRequestPacket(port, buf, len);
578 : /* Not really an error, but we don't want to proceed further */
579 15 : goto fail;
580 : }
581 :
582 15375 : if (proto == NEGOTIATE_SSL_CODE && !ssl_done)
583 : {
584 : char SSLok;
585 :
586 : #ifdef USE_SSL
587 :
588 : /*
589 : * No SSL when disabled or on Unix sockets.
590 : *
591 : * Also no SSL negotiation if we already have a direct SSL connection
592 : */
593 319 : if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX || port->ssl_in_use)
594 152 : SSLok = 'N';
595 : else
596 167 : SSLok = 'S'; /* Support for SSL */
597 : #else
598 : SSLok = 'N'; /* No support for SSL */
599 : #endif
600 :
601 319 : if (Trace_connection_negotiation)
602 : {
603 13 : if (SSLok == 'S')
604 8 : ereport(LOG,
605 : (errmsg("SSLRequest accepted")));
606 : else
607 5 : ereport(LOG,
608 : (errmsg("SSLRequest rejected")));
609 : }
610 :
611 319 : while (secure_write(port, &SSLok, 1) != 1)
612 : {
613 0 : if (errno == EINTR)
614 0 : continue; /* if interrupted, just retry */
615 0 : ereport(COMMERROR,
616 : (errcode_for_socket_access(),
617 : errmsg("failed to send SSL negotiation response: %m")));
618 32 : goto fail; /* close the connection */
619 : }
620 :
621 : #ifdef USE_SSL
622 319 : if (SSLok == 'S' && secure_open_server(port) == -1)
623 32 : goto fail;
624 : #endif
625 :
626 286 : pfree(buf);
627 286 : buf = NULL;
628 :
629 : /*
630 : * At this point we should have no data already buffered. If we do,
631 : * it was received before we performed the SSL handshake, so it wasn't
632 : * encrypted and indeed may have been injected by a man-in-the-middle.
633 : * We report this case to the client.
634 : */
635 286 : if (pq_buffer_remaining_data() > 0)
636 0 : ereport(FATAL,
637 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
638 : errmsg("received unencrypted data after SSL request"),
639 : errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
640 :
641 : /*
642 : * regular startup packet, cancel, etc packet should follow, but not
643 : * another SSL negotiation request, and a GSS request should only
644 : * follow if SSL was rejected (client may negotiate in either order)
645 : */
646 286 : ssl_done = true;
647 286 : if (SSLok == 'S')
648 : {
649 : /*
650 : * We are done with SSL and negotiated correctly, so consider the
651 : * same for GSS.
652 : */
653 134 : gss_done = true;
654 : }
655 286 : goto retry;
656 : }
657 15056 : else if (proto == NEGOTIATE_GSS_CODE && !gss_done)
658 : {
659 1 : char GSSok = 'N';
660 :
661 : #ifdef ENABLE_GSS
662 : /* No GSSAPI encryption when on Unix socket */
663 : if (port->laddr.addr.ss_family != AF_UNIX)
664 : GSSok = 'G';
665 : #endif
666 :
667 1 : if (Trace_connection_negotiation)
668 : {
669 1 : if (GSSok == 'G')
670 0 : ereport(LOG,
671 : (errmsg("GSSENCRequest accepted")));
672 : else
673 1 : ereport(LOG,
674 : (errmsg("GSSENCRequest rejected")));
675 : }
676 :
677 1 : while (secure_write(port, &GSSok, 1) != 1)
678 : {
679 0 : if (errno == EINTR)
680 0 : continue;
681 0 : ereport(COMMERROR,
682 : (errcode_for_socket_access(),
683 : errmsg("failed to send GSSAPI negotiation response: %m")));
684 0 : goto fail; /* close the connection */
685 : }
686 :
687 : #ifdef ENABLE_GSS
688 : if (GSSok == 'G' && secure_open_gssapi(port) == -1)
689 : goto fail;
690 : #endif
691 :
692 1 : pfree(buf);
693 1 : buf = NULL;
694 :
695 : /*
696 : * At this point we should have no data already buffered. If we do,
697 : * it was received before we performed the GSS handshake, so it wasn't
698 : * encrypted and indeed may have been injected by a man-in-the-middle.
699 : * We report this case to the client.
700 : */
701 1 : if (pq_buffer_remaining_data() > 0)
702 0 : ereport(FATAL,
703 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
704 : errmsg("received unencrypted data after GSSAPI encryption request"),
705 : errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
706 :
707 : /*
708 : * regular startup packet, cancel, etc packet should follow, but not
709 : * another GSS negotiation request, and an SSL request should only
710 : * follow if GSS was rejected (client may negotiate in either order)
711 : */
712 1 : gss_done = true;
713 1 : if (GSSok == 'G')
714 : {
715 : /*
716 : * We are done with GSS and negotiated correctly, so consider the
717 : * same for SSL.
718 : */
719 0 : ssl_done = true;
720 : }
721 1 : goto retry;
722 : }
723 :
724 : /* Could add additional special packet types here */
725 :
726 : /*
727 : * Set FrontendProtocol now so that ereport() knows what format to send if
728 : * we fail during startup. We use the protocol version requested by the
729 : * client unless it's higher than the latest version we support. It's
730 : * possible that error message fields might look different in newer
731 : * protocol versions, but that's something those new clients should be
732 : * able to deal with.
733 : */
734 15055 : FrontendProtocol = Min(proto, PG_PROTOCOL_LATEST);
735 :
736 : /* Check that the major protocol version is in range. */
737 15055 : if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
738 15055 : PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST))
739 1 : ereport(FATAL,
740 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
741 : errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u",
742 : PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto),
743 : PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST),
744 : PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST),
745 : PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST))));
746 :
747 : /*
748 : * Now fetch parameters out of startup packet and save them into the Port
749 : * structure.
750 : */
751 15054 : oldcontext = MemoryContextSwitchTo(TopMemoryContext);
752 :
753 : /* Handle protocol version 3 startup packet */
754 : {
755 15054 : int32 offset = sizeof(ProtocolVersion);
756 15054 : List *unrecognized_protocol_options = NIL;
757 :
758 : /*
759 : * Scan packet body for name/option pairs. We can assume any string
760 : * beginning within the packet body is null-terminated, thanks to
761 : * zeroing extra byte above.
762 : */
763 15054 : port->guc_options = NIL;
764 :
765 87765 : while (offset < len)
766 : {
767 87765 : char *nameptr = buf + offset;
768 : int32 valoffset;
769 : char *valptr;
770 :
771 87765 : if (*nameptr == '\0')
772 15054 : break; /* found packet terminator */
773 72711 : valoffset = offset + strlen(nameptr) + 1;
774 72711 : if (valoffset >= len)
775 0 : break; /* missing value, will complain below */
776 72711 : valptr = buf + valoffset;
777 :
778 72711 : if (strcmp(nameptr, "database") == 0)
779 15054 : port->database_name = pstrdup(valptr);
780 57657 : else if (strcmp(nameptr, "user") == 0)
781 15054 : port->user_name = pstrdup(valptr);
782 42603 : else if (strcmp(nameptr, "options") == 0)
783 4575 : port->cmdline_options = pstrdup(valptr);
784 38028 : else if (strcmp(nameptr, "replication") == 0)
785 : {
786 : /*
787 : * Due to backward compatibility concerns the replication
788 : * parameter is a hybrid beast which allows the value to be
789 : * either boolean or the string 'database'. The latter
790 : * connects to a specific database which is e.g. required for
791 : * logical decoding while.
792 : */
793 1369 : if (strcmp(valptr, "database") == 0)
794 : {
795 826 : am_walsender = true;
796 826 : am_db_walsender = true;
797 : }
798 543 : else if (!parse_bool(valptr, &am_walsender))
799 0 : ereport(FATAL,
800 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
801 : errmsg("invalid value for parameter \"%s\": \"%s\"",
802 : "replication",
803 : valptr),
804 : errhint("Valid values are: \"false\", 0, \"true\", 1, \"database\".")));
805 : }
806 36659 : else if (strncmp(nameptr, "_pq_.", 5) == 0)
807 : {
808 : /*
809 : * Any option beginning with _pq_. is reserved for use as a
810 : * protocol-level option, but at present no such options are
811 : * defined.
812 : */
813 : unrecognized_protocol_options =
814 15033 : lappend(unrecognized_protocol_options, pstrdup(nameptr));
815 : }
816 : else
817 : {
818 : /* Assume it's a generic GUC option */
819 21626 : port->guc_options = lappend(port->guc_options,
820 21626 : pstrdup(nameptr));
821 21626 : port->guc_options = lappend(port->guc_options,
822 21626 : pstrdup(valptr));
823 :
824 : /*
825 : * Copy application_name to port if we come across it. This
826 : * is done so we can log the application_name in the
827 : * connection authorization message. Note that the GUC would
828 : * be used but we haven't gone through GUC setup yet.
829 : */
830 21626 : if (strcmp(nameptr, "application_name") == 0)
831 : {
832 15049 : port->application_name = pg_clean_ascii(valptr, 0);
833 : }
834 : }
835 72711 : offset = valoffset + strlen(valptr) + 1;
836 : }
837 :
838 : /*
839 : * If we didn't find a packet terminator exactly at the end of the
840 : * given packet length, complain.
841 : */
842 15054 : if (offset != len - 1)
843 0 : ereport(FATAL,
844 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
845 : errmsg("invalid startup packet layout: expected terminator as last byte")));
846 :
847 : /*
848 : * If the client requested a newer protocol version or if the client
849 : * requested any protocol options we didn't recognize, let them know
850 : * the newest minor protocol version we do support and the names of
851 : * any unrecognized options.
852 : */
853 15054 : if (PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST) ||
854 : unrecognized_protocol_options != NIL)
855 15033 : SendNegotiateProtocolVersion(unrecognized_protocol_options);
856 :
857 15054 : list_free_deep(unrecognized_protocol_options);
858 : }
859 :
860 : /* Check a user name was given. */
861 15054 : if (port->user_name == NULL || port->user_name[0] == '\0')
862 0 : ereport(FATAL,
863 : (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
864 : errmsg("no PostgreSQL user name specified in startup packet")));
865 :
866 : /* The database defaults to the user name. */
867 15054 : if (port->database_name == NULL || port->database_name[0] == '\0')
868 0 : port->database_name = pstrdup(port->user_name);
869 :
870 : /*
871 : * Truncate given database and user names to length of a Postgres name.
872 : * This avoids lookup failures when overlength names are given.
873 : */
874 15054 : if (strlen(port->database_name) >= NAMEDATALEN)
875 0 : port->database_name[NAMEDATALEN - 1] = '\0';
876 15054 : if (strlen(port->user_name) >= NAMEDATALEN)
877 0 : port->user_name[NAMEDATALEN - 1] = '\0';
878 :
879 : Assert(MyBackendType == B_BACKEND || MyBackendType == B_DEAD_END_BACKEND);
880 15054 : if (am_walsender)
881 1369 : MyBackendType = B_WAL_SENDER;
882 :
883 : /*
884 : * Normal walsender backends, e.g. for streaming replication, are not
885 : * connected to a particular database. But walsenders used for logical
886 : * replication need to connect to a specific database. We allow streaming
887 : * replication commands to be issued even if connected to a database as it
888 : * can make sense to first make a basebackup and then stream changes
889 : * starting from that.
890 : */
891 15054 : if (am_walsender && !am_db_walsender)
892 543 : port->database_name[0] = '\0';
893 :
894 : /*
895 : * Done filling the Port structure
896 : */
897 15054 : MemoryContextSwitchTo(oldcontext);
898 :
899 15054 : pfree(buf);
900 :
901 15054 : return STATUS_OK;
902 :
903 63 : fail:
904 : /* be tidy, just to avoid Valgrind complaints */
905 63 : if (buf)
906 47 : pfree(buf);
907 :
908 63 : return STATUS_ERROR;
909 : }
910 :
911 : /*
912 : * The client has sent a cancel request packet, not a normal
913 : * start-a-new-connection packet. Perform the necessary processing. Nothing
914 : * is sent back to the client.
915 : */
916 : static void
917 15 : ProcessCancelRequestPacket(Port *port, void *pkt, int pktlen)
918 : {
919 : CancelRequestPacket *canc;
920 : int len;
921 :
922 15 : if (pktlen < offsetof(CancelRequestPacket, cancelAuthCode))
923 : {
924 0 : ereport(COMMERROR,
925 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
926 : errmsg("invalid length of cancel request packet")));
927 0 : return;
928 : }
929 15 : len = pktlen - offsetof(CancelRequestPacket, cancelAuthCode);
930 15 : if (len == 0 || len > 256)
931 : {
932 0 : ereport(COMMERROR,
933 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
934 : errmsg("invalid length of cancel key in cancel request packet")));
935 0 : return;
936 : }
937 :
938 15 : canc = (CancelRequestPacket *) pkt;
939 15 : SendCancelRequest(pg_ntoh32(canc->backendPID), canc->cancelAuthCode, len);
940 : }
941 :
942 : /*
943 : * Send a NegotiateProtocolVersion to the client. This lets the client know
944 : * that they have either requested a newer minor protocol version than we are
945 : * able to speak, or at least one protocol option that we don't understand, or
946 : * possibly both. FrontendProtocol has already been set to the version
947 : * requested by the client or the highest version we know how to speak,
948 : * whichever is older. If the highest version that we know how to speak is too
949 : * old for the client, it can abandon the connection.
950 : *
951 : * We also include in the response a list of protocol options we didn't
952 : * understand. This allows clients to include optional parameters that might
953 : * be present either in newer protocol versions or third-party protocol
954 : * extensions without fear of having to reconnect if those options are not
955 : * understood, while at the same time making certain that the client is aware
956 : * of which options were actually accepted.
957 : */
958 : static void
959 15033 : SendNegotiateProtocolVersion(List *unrecognized_protocol_options)
960 : {
961 : StringInfoData buf;
962 : ListCell *lc;
963 :
964 15033 : pq_beginmessage(&buf, PqMsg_NegotiateProtocolVersion);
965 15033 : pq_sendint32(&buf, FrontendProtocol);
966 15033 : pq_sendint32(&buf, list_length(unrecognized_protocol_options));
967 30066 : foreach(lc, unrecognized_protocol_options)
968 15033 : pq_sendstring(&buf, lfirst(lc));
969 15033 : pq_endmessage(&buf);
970 :
971 : /* no need to flush, some other message will follow */
972 15033 : }
973 :
974 :
975 : /*
976 : * SIGTERM while processing startup packet.
977 : *
978 : * Running proc_exit() from a signal handler would be quite unsafe.
979 : * However, since we have not yet touched shared memory, we can just
980 : * pull the plug and exit without running any atexit handlers.
981 : *
982 : * One might be tempted to try to send a message, or log one, indicating
983 : * why we are disconnecting. However, that would be quite unsafe in itself.
984 : * Also, it seems undesirable to provide clues about the database's state
985 : * to a client that has not yet completed authentication, or even sent us
986 : * a startup packet.
987 : */
988 : static void
989 0 : process_startup_packet_die(SIGNAL_ARGS)
990 : {
991 0 : _exit(1);
992 : }
993 :
994 : /*
995 : * Timeout while processing startup packet.
996 : * As for process_startup_packet_die(), we exit via _exit(1).
997 : */
998 : static void
999 0 : StartupPacketTimeoutHandler(void)
1000 : {
1001 0 : _exit(1);
1002 : }
1003 :
1004 : /*
1005 : * Helper for the log_connections GUC check hook.
1006 : *
1007 : * `elemlist` is a listified version of the string input passed to the
1008 : * log_connections GUC check hook, check_log_connections().
1009 : * check_log_connections() is responsible for cleaning up `elemlist`.
1010 : *
1011 : * validate_log_connections_options() returns false if an error was
1012 : * encountered and the GUC input could not be validated and true otherwise.
1013 : *
1014 : * `flags` returns the flags that should be stored in the log_connections GUC
1015 : * by its assign hook.
1016 : */
1017 : static bool
1018 1447 : validate_log_connections_options(List *elemlist, uint32 *flags)
1019 : {
1020 : ListCell *l;
1021 : char *item;
1022 :
1023 : /*
1024 : * For backwards compatibility, we accept these tokens by themselves.
1025 : *
1026 : * Prior to PostgreSQL 18, log_connections was a boolean GUC that accepted
1027 : * any unambiguous substring of 'true', 'false', 'yes', 'no', 'on', and
1028 : * 'off'. Since log_connections became a list of strings in 18, we only
1029 : * accept complete option strings.
1030 : */
1031 : static const struct config_enum_entry compat_options[] = {
1032 : {"off", 0},
1033 : {"false", 0},
1034 : {"no", 0},
1035 : {"0", 0},
1036 : {"on", LOG_CONNECTION_ON},
1037 : {"true", LOG_CONNECTION_ON},
1038 : {"yes", LOG_CONNECTION_ON},
1039 : {"1", LOG_CONNECTION_ON},
1040 : };
1041 :
1042 1447 : *flags = 0;
1043 :
1044 : /* If an empty string was passed, we're done */
1045 1447 : if (list_length(elemlist) == 0)
1046 1295 : return true;
1047 :
1048 : /*
1049 : * Now check for the backwards compatibility options. They must always be
1050 : * specified on their own, so we error out if the first option is a
1051 : * backwards compatibility option and other options are also specified.
1052 : */
1053 152 : item = linitial(elemlist);
1054 :
1055 1364 : for (size_t i = 0; i < lengthof(compat_options); i++)
1056 : {
1057 1213 : struct config_enum_entry option = compat_options[i];
1058 :
1059 1213 : if (pg_strcasecmp(item, option.name) != 0)
1060 1212 : continue;
1061 :
1062 1 : if (list_length(elemlist) > 1)
1063 : {
1064 0 : GUC_check_errdetail("Cannot specify log_connections option \"%s\" in a list with other options.",
1065 : item);
1066 1 : return false;
1067 : }
1068 :
1069 1 : *flags = option.val;
1070 1 : return true;
1071 : }
1072 :
1073 : /* Now check the aspect options. The empty string was already handled */
1074 341 : foreach(l, elemlist)
1075 : {
1076 : static const struct config_enum_entry options[] = {
1077 : {"receipt", LOG_CONNECTION_RECEIPT},
1078 : {"authentication", LOG_CONNECTION_AUTHENTICATION},
1079 : {"authorization", LOG_CONNECTION_AUTHORIZATION},
1080 : {"setup_durations", LOG_CONNECTION_SETUP_DURATIONS},
1081 : {"all", LOG_CONNECTION_ALL},
1082 : };
1083 :
1084 190 : item = lfirst(l);
1085 676 : for (size_t i = 0; i < lengthof(options); i++)
1086 : {
1087 676 : struct config_enum_entry option = options[i];
1088 :
1089 676 : if (pg_strcasecmp(item, option.name) == 0)
1090 : {
1091 190 : *flags |= option.val;
1092 190 : goto next;
1093 : }
1094 : }
1095 :
1096 0 : GUC_check_errdetail("Invalid option \"%s\".", item);
1097 0 : return false;
1098 :
1099 190 : next: ;
1100 : }
1101 :
1102 151 : return true;
1103 : }
1104 :
1105 :
1106 : /*
1107 : * GUC check hook for log_connections
1108 : */
1109 : bool
1110 1447 : check_log_connections(char **newval, void **extra, GucSource source)
1111 : {
1112 : uint32 flags;
1113 : char *rawstring;
1114 : List *elemlist;
1115 : bool success;
1116 :
1117 : /* Need a modifiable copy of string */
1118 1447 : rawstring = pstrdup(*newval);
1119 :
1120 1447 : if (!SplitIdentifierString(rawstring, ',', &elemlist))
1121 : {
1122 0 : GUC_check_errdetail("Invalid list syntax in parameter \"%s\".", "log_connections");
1123 0 : pfree(rawstring);
1124 0 : list_free(elemlist);
1125 0 : return false;
1126 : }
1127 :
1128 : /* Validation logic is all in the helper */
1129 1447 : success = validate_log_connections_options(elemlist, &flags);
1130 :
1131 : /* Time for cleanup */
1132 1447 : pfree(rawstring);
1133 1447 : list_free(elemlist);
1134 :
1135 1447 : if (!success)
1136 0 : return false;
1137 :
1138 : /*
1139 : * We succeeded, so allocate `extra` and save the flags there for use by
1140 : * assign_log_connections().
1141 : */
1142 1447 : *extra = guc_malloc(LOG, sizeof(int));
1143 1447 : if (!*extra)
1144 0 : return false;
1145 1447 : *((int *) *extra) = flags;
1146 :
1147 1447 : return true;
1148 : }
1149 :
1150 : /*
1151 : * GUC assign hook for log_connections
1152 : */
1153 : void
1154 1443 : assign_log_connections(const char *newval, void *extra)
1155 : {
1156 1443 : log_connections = *((int *) extra);
1157 1443 : }
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