Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * backend_startup.c
4 : * Backend startup code
5 : *
6 : * Portions Copyright (c) 1996-2025, 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, bool ssl_done, bool gss_done);
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 26142 : BackendMain(const void *startup_data, size_t startup_data_len)
77 : {
78 26142 : 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 26142 : 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 25516 : 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 25510 : MemoryContextSwitchTo(TopMemoryContext);
123 :
124 25510 : 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 26142 : 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 26142 : 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 26142 : if (PreAuthDelay > 0)
162 0 : pg_usleep(PreAuthDelay * 1000000L);
163 :
164 : /* This flag will remain set until InitPostgres finishes authentication */
165 26142 : 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 26142 : oldcontext = MemoryContextSwitchTo(TopMemoryContext);
177 26142 : port = MyProcPort = pq_init(client_sock);
178 26142 : MemoryContextSwitchTo(oldcontext);
179 :
180 26142 : 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 26142 : port->remote_host = "";
184 26142 : 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 26142 : pqsignal(SIGTERM, process_startup_packet_die);
197 : /* SIGQUIT handler was already set up by InitPostmasterChild */
198 26142 : InitializeTimeouts(); /* establishes SIGALRM handler */
199 26142 : sigprocmask(SIG_SETMASK, &StartupBlockSig, NULL);
200 :
201 : /*
202 : * Get the remote host name and port for logging and status display.
203 : */
204 26142 : remote_host[0] = '\0';
205 26142 : remote_port[0] = '\0';
206 26142 : 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 26142 : port->remote_host = MemoryContextStrdup(TopMemoryContext, remote_host);
219 26142 : port->remote_port = MemoryContextStrdup(TopMemoryContext, remote_port);
220 :
221 : /* And now we can log that the connection was received, if enabled */
222 26142 : if (log_connections & LOG_CONNECTION_RECEIPT)
223 : {
224 784 : if (remote_port[0])
225 292 : ereport(LOG,
226 : (errmsg("connection received: host=%s port=%s",
227 : remote_host,
228 : remote_port)));
229 : else
230 492 : 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 26142 : INJECTION_POINT("backend-initialize", NULL);
238 26142 : 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 0 : FrontendProtocol = PG_PROTOCOL(2, 0);
246 0 : 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 26142 : if (log_hostname &&
262 234 : ret == 0 &&
263 234 : strspn(remote_host, "0123456789.") < strlen(remote_host) &&
264 234 : strspn(remote_host, "0123456789ABCDEFabcdef:") < strlen(remote_host))
265 : {
266 234 : 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 26142 : RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler);
285 26142 : enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000);
286 :
287 : /* Handle direct SSL handshake */
288 26142 : status = ProcessSSLStartup(port);
289 :
290 : /*
291 : * Receive the startup packet (which might turn out to be a cancel request
292 : * packet).
293 : */
294 26142 : if (status == STATUS_OK)
295 26134 : status = ProcessStartupPacket(port, false, false);
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 26140 : if (status == STATUS_OK)
303 : {
304 26032 : switch (cac)
305 : {
306 412 : case CAC_STARTUP:
307 412 : ereport(FATAL,
308 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
309 : errmsg("the database system is starting up")));
310 : break;
311 18 : case CAC_NOTHOTSTANDBY:
312 18 : 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 18 : 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 18 : 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 78 : case CAC_SHUTDOWN:
331 78 : ereport(FATAL,
332 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
333 : errmsg("the database system is shutting down")));
334 : break;
335 6 : case CAC_RECOVERY:
336 6 : ereport(FATAL,
337 : (errcode(ERRCODE_CANNOT_CONNECT_NOW),
338 : errmsg("the database system is in recovery mode")));
339 : break;
340 2 : case CAC_TOOMANY:
341 2 : ereport(FATAL,
342 : (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
343 : errmsg("sorry, too many clients already")));
344 : break;
345 25516 : case CAC_OK:
346 25516 : break;
347 : }
348 : }
349 :
350 : /*
351 : * Disable the timeout, and prevent SIGTERM again.
352 : */
353 25624 : disable_timeout(STARTUP_PACKET_TIMEOUT, false);
354 25624 : 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 25624 : 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 25624 : if (status != STATUS_OK)
372 108 : 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 25516 : initStringInfo(&ps_data);
379 25516 : if (am_walsender)
380 2270 : appendStringInfo(&ps_data, "%s ", GetBackendTypeDesc(B_WAL_SENDER));
381 25516 : appendStringInfo(&ps_data, "%s ", port->user_name);
382 25516 : if (port->database_name[0] != '\0')
383 24604 : appendStringInfo(&ps_data, "%s ", port->database_name);
384 25516 : appendStringInfoString(&ps_data, port->remote_host);
385 25516 : if (port->remote_port[0] != '\0')
386 504 : appendStringInfo(&ps_data, "(%s)", port->remote_port);
387 :
388 25516 : init_ps_display(ps_data.data);
389 25516 : pfree(ps_data.data);
390 :
391 25516 : set_ps_display("initializing");
392 25516 : }
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 26142 : ProcessSSLStartup(Port *port)
402 : {
403 : int firstbyte;
404 :
405 : Assert(!port->ssl_in_use);
406 :
407 26142 : pq_startmsgread();
408 26142 : firstbyte = pq_peekbyte();
409 26142 : pq_endmsgread();
410 26142 : 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 4 : return STATUS_ERROR;
417 : }
418 :
419 26138 : if (firstbyte != 0x16)
420 : {
421 : /* Not an SSL handshake message */
422 26128 : 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 10 : if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX)
434 : {
435 : /* SSL not supported */
436 4 : goto reject;
437 : }
438 :
439 6 : 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 6 : 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 6 : if (Trace_connection_negotiation)
458 6 : ereport(LOG,
459 : (errmsg("direct SSL connection accepted")));
460 6 : return STATUS_OK;
461 : #else
462 : /* SSL not supported by this build */
463 : goto reject;
464 : #endif
465 :
466 4 : reject:
467 4 : if (Trace_connection_negotiation)
468 4 : ereport(LOG,
469 : (errmsg("direct SSL connection rejected")));
470 4 : 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 : * Set ssl_done and/or gss_done when negotiation of an encrypted layer
485 : * (currently, TLS or GSSAPI) is completed. A successful negotiation of either
486 : * encryption layer sets both flags, but a rejected negotiation sets only the
487 : * flag for that layer, since the client may wish to try the other one. We
488 : * should make no assumption here about the order in which the client may make
489 : * requests.
490 : */
491 : static int
492 26638 : ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
493 : {
494 : int32 len;
495 26638 : char *buf = NULL;
496 : ProtocolVersion proto;
497 : MemoryContext oldcontext;
498 :
499 26638 : pq_startmsgread();
500 :
501 : /*
502 : * Grab the first byte of the length word separately, so that we can tell
503 : * whether we have no data at all or an incomplete packet. (This might
504 : * sound inefficient, but it's not really, because of buffering in
505 : * pqcomm.c.)
506 : */
507 26638 : if (pq_getbytes(&len, 1) == EOF)
508 : {
509 : /*
510 : * If we get no data at all, don't clutter the log with a complaint;
511 : * such cases often occur for legitimate reasons. An example is that
512 : * we might be here after responding to NEGOTIATE_SSL_CODE, and if the
513 : * client didn't like our response, it'll probably just drop the
514 : * connection. Service-monitoring software also often just opens and
515 : * closes a connection without sending anything. (So do port
516 : * scanners, which may be less benign, but it's not really our job to
517 : * notice those.)
518 : */
519 30 : goto fail;
520 : }
521 :
522 26608 : if (pq_getbytes(((char *) &len) + 1, 3) == EOF)
523 : {
524 : /* Got a partial length word, so bleat about that */
525 0 : if (!ssl_done && !gss_done)
526 0 : ereport(COMMERROR,
527 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
528 : errmsg("incomplete startup packet")));
529 0 : goto fail;
530 : }
531 :
532 26608 : len = pg_ntoh32(len);
533 26608 : len -= 4;
534 :
535 26608 : if (len < (int32) sizeof(ProtocolVersion) ||
536 26608 : len > MAX_STARTUP_PACKET_LENGTH)
537 : {
538 0 : ereport(COMMERROR,
539 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
540 : errmsg("invalid length of startup packet")));
541 0 : goto fail;
542 : }
543 :
544 : /*
545 : * Allocate space to hold the startup packet, plus one extra byte that's
546 : * initialized to be zero. This ensures we will have null termination of
547 : * all strings inside the packet.
548 : */
549 26608 : buf = palloc(len + 1);
550 26608 : buf[len] = '\0';
551 :
552 26608 : if (pq_getbytes(buf, len) == EOF)
553 : {
554 0 : ereport(COMMERROR,
555 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
556 : errmsg("incomplete startup packet")));
557 0 : goto fail;
558 : }
559 26608 : pq_endmsgread();
560 :
561 : /*
562 : * The first field is either a protocol version number or a special
563 : * request code.
564 : */
565 26608 : port->proto = proto = pg_ntoh32(*((ProtocolVersion *) buf));
566 :
567 26608 : if (proto == CANCEL_REQUEST_CODE)
568 : {
569 32 : ProcessCancelRequestPacket(port, buf, len);
570 : /* Not really an error, but we don't want to proceed further */
571 32 : goto fail;
572 : }
573 :
574 26576 : if (proto == NEGOTIATE_SSL_CODE && !ssl_done)
575 : {
576 : char SSLok;
577 :
578 : #ifdef USE_SSL
579 :
580 : /*
581 : * No SSL when disabled or on Unix sockets.
582 : *
583 : * Also no SSL negotiation if we already have a direct SSL connection
584 : */
585 544 : if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX || port->ssl_in_use)
586 296 : SSLok = 'N';
587 : else
588 248 : SSLok = 'S'; /* Support for SSL */
589 : #else
590 : SSLok = 'N'; /* No support for SSL */
591 : #endif
592 :
593 544 : if (Trace_connection_negotiation)
594 : {
595 24 : if (SSLok == 'S')
596 16 : ereport(LOG,
597 : (errmsg("SSLRequest accepted")));
598 : else
599 8 : ereport(LOG,
600 : (errmsg("SSLRequest rejected")));
601 : }
602 :
603 544 : while (secure_write(port, &SSLok, 1) != 1)
604 : {
605 0 : if (errno == EINTR)
606 0 : continue; /* if interrupted, just retry */
607 0 : ereport(COMMERROR,
608 : (errcode_for_socket_access(),
609 : errmsg("failed to send SSL negotiation response: %m")));
610 38 : goto fail; /* close the connection */
611 : }
612 :
613 : #ifdef USE_SSL
614 544 : if (SSLok == 'S' && secure_open_server(port) == -1)
615 38 : goto fail;
616 : #endif
617 :
618 504 : pfree(buf);
619 :
620 : /*
621 : * At this point we should have no data already buffered. If we do,
622 : * it was received before we performed the SSL handshake, so it wasn't
623 : * encrypted and indeed may have been injected by a man-in-the-middle.
624 : * We report this case to the client.
625 : */
626 504 : if (pq_buffer_remaining_data() > 0)
627 0 : ereport(FATAL,
628 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
629 : errmsg("received unencrypted data after SSL request"),
630 : errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
631 :
632 : /*
633 : * regular startup packet, cancel, etc packet should follow, but not
634 : * another SSL negotiation request, and a GSS request should only
635 : * follow if SSL was rejected (client may negotiate in either order)
636 : */
637 504 : return ProcessStartupPacket(port, true, SSLok == 'S');
638 : }
639 26032 : else if (proto == NEGOTIATE_GSS_CODE && !gss_done)
640 : {
641 0 : char GSSok = 'N';
642 :
643 : #ifdef ENABLE_GSS
644 : /* No GSSAPI encryption when on Unix socket */
645 : if (port->laddr.addr.ss_family != AF_UNIX)
646 : GSSok = 'G';
647 : #endif
648 :
649 0 : if (Trace_connection_negotiation)
650 : {
651 0 : if (GSSok == 'G')
652 0 : ereport(LOG,
653 : (errmsg("GSSENCRequest accepted")));
654 : else
655 0 : ereport(LOG,
656 : (errmsg("GSSENCRequest rejected")));
657 : }
658 :
659 0 : while (secure_write(port, &GSSok, 1) != 1)
660 : {
661 0 : if (errno == EINTR)
662 0 : continue;
663 0 : ereport(COMMERROR,
664 : (errcode_for_socket_access(),
665 : errmsg("failed to send GSSAPI negotiation response: %m")));
666 0 : goto fail; /* close the connection */
667 : }
668 :
669 : #ifdef ENABLE_GSS
670 : if (GSSok == 'G' && secure_open_gssapi(port) == -1)
671 : goto fail;
672 : #endif
673 :
674 0 : pfree(buf);
675 :
676 : /*
677 : * At this point we should have no data already buffered. If we do,
678 : * it was received before we performed the GSS handshake, so it wasn't
679 : * encrypted and indeed may have been injected by a man-in-the-middle.
680 : * We report this case to the client.
681 : */
682 0 : if (pq_buffer_remaining_data() > 0)
683 0 : ereport(FATAL,
684 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
685 : errmsg("received unencrypted data after GSSAPI encryption request"),
686 : errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
687 :
688 : /*
689 : * regular startup packet, cancel, etc packet should follow, but not
690 : * another GSS negotiation request, and an SSL request should only
691 : * follow if GSS was rejected (client may negotiate in either order)
692 : */
693 0 : return ProcessStartupPacket(port, GSSok == 'G', true);
694 : }
695 :
696 : /* Could add additional special packet types here */
697 :
698 : /*
699 : * Set FrontendProtocol now so that ereport() knows what format to send if
700 : * we fail during startup. We use the protocol version requested by the
701 : * client unless it's higher than the latest version we support. It's
702 : * possible that error message fields might look different in newer
703 : * protocol versions, but that's something those new clients should be
704 : * able to deal with.
705 : */
706 26032 : FrontendProtocol = Min(proto, PG_PROTOCOL_LATEST);
707 :
708 : /* Check that the major protocol version is in range. */
709 26032 : if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
710 26032 : PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST))
711 0 : ereport(FATAL,
712 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
713 : errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u",
714 : PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto),
715 : PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST),
716 : PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST),
717 : PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST))));
718 :
719 : /*
720 : * Now fetch parameters out of startup packet and save them into the Port
721 : * structure.
722 : */
723 26032 : oldcontext = MemoryContextSwitchTo(TopMemoryContext);
724 :
725 : /* Handle protocol version 3 startup packet */
726 : {
727 26032 : int32 offset = sizeof(ProtocolVersion);
728 26032 : List *unrecognized_protocol_options = NIL;
729 :
730 : /*
731 : * Scan packet body for name/option pairs. We can assume any string
732 : * beginning within the packet body is null-terminated, thanks to
733 : * zeroing extra byte above.
734 : */
735 26032 : port->guc_options = NIL;
736 :
737 125512 : while (offset < len)
738 : {
739 125512 : char *nameptr = buf + offset;
740 : int32 valoffset;
741 : char *valptr;
742 :
743 125512 : if (*nameptr == '\0')
744 26032 : break; /* found packet terminator */
745 99480 : valoffset = offset + strlen(nameptr) + 1;
746 99480 : if (valoffset >= len)
747 0 : break; /* missing value, will complain below */
748 99480 : valptr = buf + valoffset;
749 :
750 99480 : if (strcmp(nameptr, "database") == 0)
751 26032 : port->database_name = pstrdup(valptr);
752 73448 : else if (strcmp(nameptr, "user") == 0)
753 26032 : port->user_name = pstrdup(valptr);
754 47416 : else if (strcmp(nameptr, "options") == 0)
755 7790 : port->cmdline_options = pstrdup(valptr);
756 39626 : else if (strcmp(nameptr, "replication") == 0)
757 : {
758 : /*
759 : * Due to backward compatibility concerns the replication
760 : * parameter is a hybrid beast which allows the value to be
761 : * either boolean or the string 'database'. The latter
762 : * connects to a specific database which is e.g. required for
763 : * logical decoding while.
764 : */
765 2368 : if (strcmp(valptr, "database") == 0)
766 : {
767 1380 : am_walsender = true;
768 1380 : am_db_walsender = true;
769 : }
770 988 : else if (!parse_bool(valptr, &am_walsender))
771 0 : ereport(FATAL,
772 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
773 : errmsg("invalid value for parameter \"%s\": \"%s\"",
774 : "replication",
775 : valptr),
776 : errhint("Valid values are: \"false\", 0, \"true\", 1, \"database\".")));
777 : }
778 37258 : else if (strncmp(nameptr, "_pq_.", 5) == 0)
779 : {
780 : /*
781 : * Any option beginning with _pq_. is reserved for use as a
782 : * protocol-level option, but at present no such options are
783 : * defined.
784 : */
785 : unrecognized_protocol_options =
786 0 : lappend(unrecognized_protocol_options, pstrdup(nameptr));
787 : }
788 : else
789 : {
790 : /* Assume it's a generic GUC option */
791 37258 : port->guc_options = lappend(port->guc_options,
792 37258 : pstrdup(nameptr));
793 37258 : port->guc_options = lappend(port->guc_options,
794 37258 : pstrdup(valptr));
795 :
796 : /*
797 : * Copy application_name to port if we come across it. This
798 : * is done so we can log the application_name in the
799 : * connection authorization message. Note that the GUC would
800 : * be used but we haven't gone through GUC setup yet.
801 : */
802 37258 : if (strcmp(nameptr, "application_name") == 0)
803 : {
804 26022 : port->application_name = pg_clean_ascii(valptr, 0);
805 : }
806 : }
807 99480 : offset = valoffset + strlen(valptr) + 1;
808 : }
809 :
810 : /*
811 : * If we didn't find a packet terminator exactly at the end of the
812 : * given packet length, complain.
813 : */
814 26032 : if (offset != len - 1)
815 0 : ereport(FATAL,
816 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
817 : errmsg("invalid startup packet layout: expected terminator as last byte")));
818 :
819 : /*
820 : * If the client requested a newer protocol version or if the client
821 : * requested any protocol options we didn't recognize, let them know
822 : * the newest minor protocol version we do support and the names of
823 : * any unrecognized options.
824 : */
825 26032 : if (PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST) ||
826 : unrecognized_protocol_options != NIL)
827 0 : SendNegotiateProtocolVersion(unrecognized_protocol_options);
828 : }
829 :
830 : /* Check a user name was given. */
831 26032 : if (port->user_name == NULL || port->user_name[0] == '\0')
832 0 : ereport(FATAL,
833 : (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
834 : errmsg("no PostgreSQL user name specified in startup packet")));
835 :
836 : /* The database defaults to the user name. */
837 26032 : if (port->database_name == NULL || port->database_name[0] == '\0')
838 0 : port->database_name = pstrdup(port->user_name);
839 :
840 : /*
841 : * Truncate given database and user names to length of a Postgres name.
842 : * This avoids lookup failures when overlength names are given.
843 : */
844 26032 : if (strlen(port->database_name) >= NAMEDATALEN)
845 0 : port->database_name[NAMEDATALEN - 1] = '\0';
846 26032 : if (strlen(port->user_name) >= NAMEDATALEN)
847 0 : port->user_name[NAMEDATALEN - 1] = '\0';
848 :
849 26032 : if (am_walsender)
850 2368 : MyBackendType = B_WAL_SENDER;
851 : else
852 23664 : MyBackendType = B_BACKEND;
853 :
854 : /*
855 : * Normal walsender backends, e.g. for streaming replication, are not
856 : * connected to a particular database. But walsenders used for logical
857 : * replication need to connect to a specific database. We allow streaming
858 : * replication commands to be issued even if connected to a database as it
859 : * can make sense to first make a basebackup and then stream changes
860 : * starting from that.
861 : */
862 26032 : if (am_walsender && !am_db_walsender)
863 988 : port->database_name[0] = '\0';
864 :
865 : /*
866 : * Done filling the Port structure
867 : */
868 26032 : MemoryContextSwitchTo(oldcontext);
869 :
870 26032 : pfree(buf);
871 :
872 26032 : return STATUS_OK;
873 :
874 100 : fail:
875 : /* be tidy, just to avoid Valgrind complaints */
876 100 : if (buf)
877 70 : pfree(buf);
878 :
879 100 : return STATUS_ERROR;
880 : }
881 :
882 : /*
883 : * The client has sent a cancel request packet, not a normal
884 : * start-a-new-connection packet. Perform the necessary processing. Nothing
885 : * is sent back to the client.
886 : */
887 : static void
888 32 : ProcessCancelRequestPacket(Port *port, void *pkt, int pktlen)
889 : {
890 : CancelRequestPacket *canc;
891 : int len;
892 :
893 32 : if (pktlen < offsetof(CancelRequestPacket, cancelAuthCode))
894 : {
895 0 : ereport(COMMERROR,
896 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
897 : errmsg("invalid length of cancel request packet")));
898 0 : return;
899 : }
900 32 : len = pktlen - offsetof(CancelRequestPacket, cancelAuthCode);
901 32 : if (len == 0 || len > 256)
902 : {
903 0 : ereport(COMMERROR,
904 : (errcode(ERRCODE_PROTOCOL_VIOLATION),
905 : errmsg("invalid length of cancel key in cancel request packet")));
906 0 : return;
907 : }
908 :
909 32 : canc = (CancelRequestPacket *) pkt;
910 32 : SendCancelRequest(pg_ntoh32(canc->backendPID), canc->cancelAuthCode, len);
911 : }
912 :
913 : /*
914 : * Send a NegotiateProtocolVersion to the client. This lets the client know
915 : * that they have either requested a newer minor protocol version than we are
916 : * able to speak, or at least one protocol option that we don't understand, or
917 : * possibly both. FrontendProtocol has already been set to the version
918 : * requested by the client or the highest version we know how to speak,
919 : * whichever is older. If the highest version that we know how to speak is too
920 : * old for the client, it can abandon the connection.
921 : *
922 : * We also include in the response a list of protocol options we didn't
923 : * understand. This allows clients to include optional parameters that might
924 : * be present either in newer protocol versions or third-party protocol
925 : * extensions without fear of having to reconnect if those options are not
926 : * understood, while at the same time making certain that the client is aware
927 : * of which options were actually accepted.
928 : */
929 : static void
930 0 : SendNegotiateProtocolVersion(List *unrecognized_protocol_options)
931 : {
932 : StringInfoData buf;
933 : ListCell *lc;
934 :
935 0 : pq_beginmessage(&buf, PqMsg_NegotiateProtocolVersion);
936 0 : pq_sendint32(&buf, FrontendProtocol);
937 0 : pq_sendint32(&buf, list_length(unrecognized_protocol_options));
938 0 : foreach(lc, unrecognized_protocol_options)
939 0 : pq_sendstring(&buf, lfirst(lc));
940 0 : pq_endmessage(&buf);
941 :
942 : /* no need to flush, some other message will follow */
943 0 : }
944 :
945 :
946 : /*
947 : * SIGTERM while processing startup packet.
948 : *
949 : * Running proc_exit() from a signal handler would be quite unsafe.
950 : * However, since we have not yet touched shared memory, we can just
951 : * pull the plug and exit without running any atexit handlers.
952 : *
953 : * One might be tempted to try to send a message, or log one, indicating
954 : * why we are disconnecting. However, that would be quite unsafe in itself.
955 : * Also, it seems undesirable to provide clues about the database's state
956 : * to a client that has not yet completed authentication, or even sent us
957 : * a startup packet.
958 : */
959 : static void
960 0 : process_startup_packet_die(SIGNAL_ARGS)
961 : {
962 0 : _exit(1);
963 : }
964 :
965 : /*
966 : * Timeout while processing startup packet.
967 : * As for process_startup_packet_die(), we exit via _exit(1).
968 : */
969 : static void
970 0 : StartupPacketTimeoutHandler(void)
971 : {
972 0 : _exit(1);
973 : }
974 :
975 : /*
976 : * Helper for the log_connections GUC check hook.
977 : *
978 : * `elemlist` is a listified version of the string input passed to the
979 : * log_connections GUC check hook, check_log_connections().
980 : * check_log_connections() is responsible for cleaning up `elemlist`.
981 : *
982 : * validate_log_connections_options() returns false if an error was
983 : * encountered and the GUC input could not be validated and true otherwise.
984 : *
985 : * `flags` returns the flags that should be stored in the log_connections GUC
986 : * by its assign hook.
987 : */
988 : static bool
989 2444 : validate_log_connections_options(List *elemlist, uint32 *flags)
990 : {
991 : ListCell *l;
992 : char *item;
993 :
994 : /*
995 : * For backwards compatibility, we accept these tokens by themselves.
996 : *
997 : * Prior to PostgreSQL 18, log_connections was a boolean GUC that accepted
998 : * any unambiguous substring of 'true', 'false', 'yes', 'no', 'on', and
999 : * 'off'. Since log_connections became a list of strings in 18, we only
1000 : * accept complete option strings.
1001 : */
1002 : static const struct config_enum_entry compat_options[] = {
1003 : {"off", 0},
1004 : {"false", 0},
1005 : {"no", 0},
1006 : {"0", 0},
1007 : {"on", LOG_CONNECTION_ON},
1008 : {"true", LOG_CONNECTION_ON},
1009 : {"yes", LOG_CONNECTION_ON},
1010 : {"1", LOG_CONNECTION_ON},
1011 : };
1012 :
1013 2444 : *flags = 0;
1014 :
1015 : /* If an empty string was passed, we're done */
1016 2444 : if (list_length(elemlist) == 0)
1017 2212 : return true;
1018 :
1019 : /*
1020 : * Now check for the backwards compatibility options. They must always be
1021 : * specified on their own, so we error out if the first option is a
1022 : * backwards compatibility option and other options are also specified.
1023 : */
1024 232 : item = linitial(elemlist);
1025 :
1026 2080 : for (size_t i = 0; i < lengthof(compat_options); i++)
1027 : {
1028 1850 : struct config_enum_entry option = compat_options[i];
1029 :
1030 1850 : if (pg_strcasecmp(item, option.name) != 0)
1031 1848 : continue;
1032 :
1033 2 : if (list_length(elemlist) > 1)
1034 : {
1035 0 : GUC_check_errdetail("Cannot specify log_connections option \"%s\" in a list with other options.",
1036 : item);
1037 2 : return false;
1038 : }
1039 :
1040 2 : *flags = option.val;
1041 2 : return true;
1042 : }
1043 :
1044 : /* Now check the aspect options. The empty string was already handled */
1045 526 : foreach(l, elemlist)
1046 : {
1047 : static const struct config_enum_entry options[] = {
1048 : {"receipt", LOG_CONNECTION_RECEIPT},
1049 : {"authentication", LOG_CONNECTION_AUTHENTICATION},
1050 : {"authorization", LOG_CONNECTION_AUTHORIZATION},
1051 : {"setup_durations", LOG_CONNECTION_SETUP_DURATIONS},
1052 : {"all", LOG_CONNECTION_ALL},
1053 : };
1054 :
1055 296 : item = lfirst(l);
1056 986 : for (size_t i = 0; i < lengthof(options); i++)
1057 : {
1058 986 : struct config_enum_entry option = options[i];
1059 :
1060 986 : if (pg_strcasecmp(item, option.name) == 0)
1061 : {
1062 296 : *flags |= option.val;
1063 296 : goto next;
1064 : }
1065 : }
1066 :
1067 0 : GUC_check_errdetail("Invalid option \"%s\".", item);
1068 0 : return false;
1069 :
1070 296 : next: ;
1071 : }
1072 :
1073 230 : return true;
1074 : }
1075 :
1076 :
1077 : /*
1078 : * GUC check hook for log_connections
1079 : */
1080 : bool
1081 2444 : check_log_connections(char **newval, void **extra, GucSource source)
1082 : {
1083 : uint32 flags;
1084 : char *rawstring;
1085 : List *elemlist;
1086 : bool success;
1087 :
1088 : /* Need a modifiable copy of string */
1089 2444 : rawstring = pstrdup(*newval);
1090 :
1091 2444 : if (!SplitIdentifierString(rawstring, ',', &elemlist))
1092 : {
1093 0 : GUC_check_errdetail("Invalid list syntax in parameter \"%s\".", "log_connections");
1094 0 : pfree(rawstring);
1095 0 : list_free(elemlist);
1096 0 : return false;
1097 : }
1098 :
1099 : /* Validation logic is all in the helper */
1100 2444 : success = validate_log_connections_options(elemlist, &flags);
1101 :
1102 : /* Time for cleanup */
1103 2444 : pfree(rawstring);
1104 2444 : list_free(elemlist);
1105 :
1106 2444 : if (!success)
1107 0 : return false;
1108 :
1109 : /*
1110 : * We succeeded, so allocate `extra` and save the flags there for use by
1111 : * assign_log_connections().
1112 : */
1113 2444 : *extra = guc_malloc(LOG, sizeof(int));
1114 2444 : if (!*extra)
1115 0 : return false;
1116 2444 : *((int *) *extra) = flags;
1117 :
1118 2444 : return true;
1119 : }
1120 :
1121 : /*
1122 : * GUC assign hook for log_connections
1123 : */
1124 : void
1125 2436 : assign_log_connections(const char *newval, void *extra)
1126 : {
1127 2436 : log_connections = *((int *) extra);
1128 2436 : }
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