Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * fe-auth-oauth.c
4 : * The front-end (client) implementation of OAuth/OIDC authentication
5 : * using the SASL OAUTHBEARER mechanism.
6 : *
7 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : * IDENTIFICATION
11 : * src/interfaces/libpq/fe-auth-oauth.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 :
16 : #include "postgres_fe.h"
17 :
18 : #ifdef USE_DYNAMIC_OAUTH
19 : #include <dlfcn.h>
20 : #endif
21 :
22 : #include "common/base64.h"
23 : #include "common/hmac.h"
24 : #include "common/jsonapi.h"
25 : #include "common/oauth-common.h"
26 : #include "fe-auth.h"
27 : #include "fe-auth-oauth.h"
28 : #include "mb/pg_wchar.h"
29 : #include "oauth-debug.h"
30 : #include "pg_config_paths.h"
31 : #include "utils/memdebug.h"
32 :
33 : static PostgresPollingStatusType do_async(fe_oauth_state *state,
34 : PGoauthBearerRequestV2 *request);
35 : static void do_cleanup(fe_oauth_state *state, PGoauthBearerRequestV2 *request);
36 : static void poison_req_v2(PGoauthBearerRequestV2 *request, bool poison);
37 :
38 : /* The exported OAuth callback mechanism. */
39 : static void *oauth_init(PGconn *conn, const char *password,
40 : const char *sasl_mechanism);
41 : static SASLStatus oauth_exchange(void *opaq, bool final,
42 : char *input, int inputlen,
43 : char **output, int *outputlen);
44 : static bool oauth_channel_bound(void *opaq);
45 : static void oauth_free(void *opaq);
46 :
47 : const pg_fe_sasl_mech pg_oauth_mech = {
48 : oauth_init,
49 : oauth_exchange,
50 : oauth_channel_bound,
51 : oauth_free,
52 : };
53 :
54 : /*
55 : * Initializes mechanism state for OAUTHBEARER.
56 : *
57 : * For a full description of the API, see libpq/fe-auth-sasl.h.
58 : */
59 : static void *
60 0 : oauth_init(PGconn *conn, const char *password,
61 : const char *sasl_mechanism)
62 : {
63 : fe_oauth_state *state;
64 :
65 : /*
66 : * We only support one SASL mechanism here; anything else is programmer
67 : * error.
68 : */
69 : Assert(sasl_mechanism != NULL);
70 : Assert(strcmp(sasl_mechanism, OAUTHBEARER_NAME) == 0);
71 :
72 0 : state = calloc(1, sizeof(*state));
73 0 : if (!state)
74 0 : return NULL;
75 :
76 0 : state->step = FE_OAUTH_INIT;
77 0 : state->conn = conn;
78 :
79 0 : return state;
80 : }
81 :
82 : /*
83 : * Frees the state allocated by oauth_init().
84 : *
85 : * This handles only mechanism state tied to the connection lifetime; state
86 : * stored in state->async_ctx is freed up either immediately after the
87 : * authentication handshake succeeds, or before the mechanism is cleaned up on
88 : * failure. See pg_fe_cleanup_oauth_flow() and cleanup_oauth_flow().
89 : */
90 : static void
91 0 : oauth_free(void *opaq)
92 : {
93 0 : fe_oauth_state *state = opaq;
94 :
95 : /* Any async authentication state should have been cleaned up already. */
96 : Assert(!state->async_ctx);
97 :
98 0 : free(state);
99 0 : }
100 :
101 : #define kvsep "\x01"
102 :
103 : /*
104 : * Constructs an OAUTHBEARER client initial response (RFC 7628, Sec. 3.1).
105 : *
106 : * If discover is true, the initial response will contain a request for the
107 : * server's required OAuth parameters (Sec. 4.3). Otherwise, conn->token must
108 : * be set; it will be sent as the connection's bearer token.
109 : *
110 : * Returns the response as a null-terminated string, or NULL on error.
111 : */
112 : static char *
113 0 : client_initial_response(PGconn *conn, bool discover)
114 : {
115 : static const char *const resp_format = "n,," kvsep "auth=%s%s" kvsep kvsep;
116 :
117 : PQExpBufferData buf;
118 : const char *authn_scheme;
119 0 : char *response = NULL;
120 0 : const char *token = conn->oauth_token;
121 :
122 0 : if (discover)
123 : {
124 : /* Parameter discovery uses a completely empty auth value. */
125 0 : authn_scheme = token = "";
126 : }
127 : else
128 : {
129 : /*
130 : * Use a Bearer authentication scheme (RFC 6750, Sec. 2.1). A trailing
131 : * space is used as a separator.
132 : */
133 0 : authn_scheme = "Bearer ";
134 :
135 : /* conn->token must have been set in this case. */
136 0 : if (!token)
137 : {
138 : Assert(false);
139 0 : libpq_append_conn_error(conn,
140 : "internal error: no OAuth token was set for the connection");
141 0 : return NULL;
142 : }
143 : }
144 :
145 0 : initPQExpBuffer(&buf);
146 0 : appendPQExpBuffer(&buf, resp_format, authn_scheme, token);
147 :
148 0 : if (!PQExpBufferDataBroken(buf))
149 0 : response = strdup(buf.data);
150 0 : termPQExpBuffer(&buf);
151 :
152 0 : if (!response)
153 0 : libpq_append_conn_error(conn, "out of memory");
154 :
155 0 : return response;
156 : }
157 :
158 : /*
159 : * JSON Parser (for the OAUTHBEARER error result)
160 : */
161 :
162 : /* Relevant JSON fields in the error result object. */
163 : #define ERROR_STATUS_FIELD "status"
164 : #define ERROR_SCOPE_FIELD "scope"
165 : #define ERROR_OPENID_CONFIGURATION_FIELD "openid-configuration"
166 :
167 : /*
168 : * Limit the maximum number of nested objects/arrays. Because OAUTHBEARER
169 : * doesn't have any defined extensions for its JSON yet, we can be much more
170 : * conservative here than with libpq-oauth's MAX_OAUTH_NESTING_LEVEL; we expect
171 : * a nesting level of 1 in practice.
172 : */
173 : #define MAX_SASL_NESTING_LEVEL 8
174 :
175 : struct json_ctx
176 : {
177 : char *errmsg; /* any non-NULL value stops all processing */
178 : PQExpBufferData errbuf; /* backing memory for errmsg */
179 : int nested; /* nesting level (zero is the top) */
180 :
181 : const char *target_field_name; /* points to a static allocation */
182 : char **target_field; /* see below */
183 :
184 : /* target_field, if set, points to one of the following: */
185 : char *status;
186 : char *scope;
187 : char *discovery_uri;
188 : };
189 :
190 : #define oauth_json_has_error(ctx) \
191 : (PQExpBufferDataBroken((ctx)->errbuf) || (ctx)->errmsg)
192 :
193 : #define oauth_json_set_error(ctx, fmt, ...) \
194 : do { \
195 : appendPQExpBuffer(&(ctx)->errbuf, libpq_gettext(fmt), ##__VA_ARGS__); \
196 : (ctx)->errmsg = (ctx)->errbuf.data; \
197 : } while (0)
198 :
199 : /* An untranslated version of oauth_json_set_error(). */
200 : #define oauth_json_set_error_internal(ctx, ...) \
201 : do { \
202 : appendPQExpBuffer(&(ctx)->errbuf, __VA_ARGS__); \
203 : (ctx)->errmsg = (ctx)->errbuf.data; \
204 : } while (0)
205 :
206 : static JsonParseErrorType
207 0 : oauth_json_object_start(void *state)
208 : {
209 0 : struct json_ctx *ctx = state;
210 :
211 0 : if (ctx->target_field)
212 : {
213 : Assert(ctx->nested == 1);
214 :
215 0 : oauth_json_set_error(ctx,
216 : "field \"%s\" must be a string",
217 : ctx->target_field_name);
218 : }
219 :
220 0 : ++ctx->nested;
221 0 : if (ctx->nested > MAX_SASL_NESTING_LEVEL)
222 0 : oauth_json_set_error(ctx, "JSON is too deeply nested");
223 :
224 0 : return oauth_json_has_error(ctx) ? JSON_SEM_ACTION_FAILED : JSON_SUCCESS;
225 : }
226 :
227 : static JsonParseErrorType
228 0 : oauth_json_object_end(void *state)
229 : {
230 0 : struct json_ctx *ctx = state;
231 :
232 0 : --ctx->nested;
233 0 : return JSON_SUCCESS;
234 : }
235 :
236 : static JsonParseErrorType
237 0 : oauth_json_object_field_start(void *state, char *name, bool isnull)
238 : {
239 0 : struct json_ctx *ctx = state;
240 :
241 : /* Only top-level keys are considered. */
242 0 : if (ctx->nested == 1)
243 : {
244 0 : if (strcmp(name, ERROR_STATUS_FIELD) == 0)
245 : {
246 0 : ctx->target_field_name = ERROR_STATUS_FIELD;
247 0 : ctx->target_field = &ctx->status;
248 : }
249 0 : else if (strcmp(name, ERROR_SCOPE_FIELD) == 0)
250 : {
251 0 : ctx->target_field_name = ERROR_SCOPE_FIELD;
252 0 : ctx->target_field = &ctx->scope;
253 : }
254 0 : else if (strcmp(name, ERROR_OPENID_CONFIGURATION_FIELD) == 0)
255 : {
256 0 : ctx->target_field_name = ERROR_OPENID_CONFIGURATION_FIELD;
257 0 : ctx->target_field = &ctx->discovery_uri;
258 : }
259 : }
260 :
261 0 : return JSON_SUCCESS;
262 : }
263 :
264 : static JsonParseErrorType
265 0 : oauth_json_array_start(void *state)
266 : {
267 0 : struct json_ctx *ctx = state;
268 :
269 0 : if (!ctx->nested)
270 : {
271 0 : oauth_json_set_error(ctx, "top-level element must be an object");
272 : }
273 0 : else if (ctx->target_field)
274 : {
275 : Assert(ctx->nested == 1);
276 :
277 0 : oauth_json_set_error(ctx,
278 : "field \"%s\" must be a string",
279 : ctx->target_field_name);
280 : }
281 :
282 0 : ++ctx->nested;
283 0 : if (ctx->nested > MAX_SASL_NESTING_LEVEL)
284 0 : oauth_json_set_error(ctx, "JSON is too deeply nested");
285 :
286 0 : return oauth_json_has_error(ctx) ? JSON_SEM_ACTION_FAILED : JSON_SUCCESS;
287 : }
288 :
289 : static JsonParseErrorType
290 0 : oauth_json_array_end(void *state)
291 : {
292 0 : struct json_ctx *ctx = state;
293 :
294 0 : --ctx->nested;
295 0 : return JSON_SUCCESS;
296 : }
297 :
298 : static JsonParseErrorType
299 0 : oauth_json_scalar(void *state, char *token, JsonTokenType type)
300 : {
301 0 : struct json_ctx *ctx = state;
302 :
303 0 : if (!ctx->nested)
304 : {
305 0 : oauth_json_set_error(ctx, "top-level element must be an object");
306 0 : return JSON_SEM_ACTION_FAILED;
307 : }
308 :
309 0 : if (ctx->target_field)
310 : {
311 0 : if (ctx->nested != 1)
312 : {
313 : /*
314 : * ctx->target_field should not have been set for nested keys.
315 : * Assert and don't continue any further for production builds.
316 : */
317 : Assert(false);
318 0 : oauth_json_set_error_internal(ctx,
319 : "internal error: target scalar found at nesting level %d during OAUTHBEARER parsing",
320 : ctx->nested);
321 0 : return JSON_SEM_ACTION_FAILED;
322 : }
323 :
324 : /*
325 : * We don't allow duplicate field names; error out if the target has
326 : * already been set.
327 : */
328 0 : if (*ctx->target_field)
329 : {
330 0 : oauth_json_set_error(ctx,
331 : "field \"%s\" is duplicated",
332 : ctx->target_field_name);
333 0 : return JSON_SEM_ACTION_FAILED;
334 : }
335 :
336 : /* The only fields we support are strings. */
337 0 : if (type != JSON_TOKEN_STRING)
338 : {
339 0 : oauth_json_set_error(ctx,
340 : "field \"%s\" must be a string",
341 : ctx->target_field_name);
342 0 : return JSON_SEM_ACTION_FAILED;
343 : }
344 :
345 0 : *ctx->target_field = strdup(token);
346 0 : if (!*ctx->target_field)
347 0 : return JSON_OUT_OF_MEMORY;
348 :
349 0 : ctx->target_field = NULL;
350 0 : ctx->target_field_name = NULL;
351 : }
352 : else
353 : {
354 : /* otherwise we just ignore it */
355 : }
356 :
357 0 : return JSON_SUCCESS;
358 : }
359 :
360 : #define HTTPS_SCHEME "https://"
361 : #define HTTP_SCHEME "http://"
362 :
363 : /* We support both well-known suffixes defined by RFC 8414. */
364 : #define WK_PREFIX "/.well-known/"
365 : #define OPENID_WK_SUFFIX "openid-configuration"
366 : #define OAUTH_WK_SUFFIX "oauth-authorization-server"
367 :
368 : /*
369 : * Derives an issuer identifier from one of our recognized .well-known URIs,
370 : * using the rules in RFC 8414.
371 : */
372 : static char *
373 0 : issuer_from_well_known_uri(PGconn *conn, const char *wkuri)
374 : {
375 0 : const char *authority_start = NULL;
376 : const char *wk_start;
377 : const char *wk_end;
378 : char *issuer;
379 : ptrdiff_t start_offset,
380 : end_offset;
381 : size_t end_len;
382 :
383 : /*
384 : * https:// is required for issuer identifiers (RFC 8414, Sec. 2; OIDC
385 : * Discovery 1.0, Sec. 3). This is a case-insensitive comparison at this
386 : * level (but issuer identifier comparison at the level above this is
387 : * case-sensitive, so in practice it's probably moot).
388 : */
389 0 : if (pg_strncasecmp(wkuri, HTTPS_SCHEME, strlen(HTTPS_SCHEME)) == 0)
390 0 : authority_start = wkuri + strlen(HTTPS_SCHEME);
391 :
392 0 : if (!authority_start
393 0 : && (oauth_parse_debug_flags() & OAUTHDEBUG_UNSAFE_HTTP)
394 0 : && pg_strncasecmp(wkuri, HTTP_SCHEME, strlen(HTTP_SCHEME)) == 0)
395 : {
396 : /* Allow http:// for testing only. */
397 0 : authority_start = wkuri + strlen(HTTP_SCHEME);
398 : }
399 :
400 0 : if (!authority_start)
401 : {
402 0 : libpq_append_conn_error(conn,
403 : "OAuth discovery URI \"%s\" must use HTTPS",
404 : wkuri);
405 0 : return NULL;
406 : }
407 :
408 : /*
409 : * Well-known URIs in general may support queries and fragments, but the
410 : * two types we support here do not. (They must be constructed from the
411 : * components of issuer identifiers, which themselves may not contain any
412 : * queries or fragments.)
413 : *
414 : * It's important to check this first, to avoid getting tricked later by a
415 : * prefix buried inside a query or fragment.
416 : */
417 0 : if (strpbrk(authority_start, "?#") != NULL)
418 : {
419 0 : libpq_append_conn_error(conn,
420 : "OAuth discovery URI \"%s\" must not contain query or fragment components",
421 : wkuri);
422 0 : return NULL;
423 : }
424 :
425 : /*
426 : * Find the start of the .well-known prefix. IETF rules (RFC 8615) state
427 : * this must be at the beginning of the path component, but OIDC defined
428 : * it at the end instead (OIDC Discovery 1.0, Sec. 4), so we have to
429 : * search for it anywhere.
430 : */
431 0 : wk_start = strstr(authority_start, WK_PREFIX);
432 0 : if (!wk_start)
433 : {
434 0 : libpq_append_conn_error(conn,
435 : "OAuth discovery URI \"%s\" is not a .well-known URI",
436 : wkuri);
437 0 : return NULL;
438 : }
439 :
440 : /*
441 : * Now find the suffix type. We only support the two defined in OIDC
442 : * Discovery 1.0 and RFC 8414.
443 : */
444 0 : wk_end = wk_start + strlen(WK_PREFIX);
445 :
446 0 : if (strncmp(wk_end, OPENID_WK_SUFFIX, strlen(OPENID_WK_SUFFIX)) == 0)
447 0 : wk_end += strlen(OPENID_WK_SUFFIX);
448 0 : else if (strncmp(wk_end, OAUTH_WK_SUFFIX, strlen(OAUTH_WK_SUFFIX)) == 0)
449 0 : wk_end += strlen(OAUTH_WK_SUFFIX);
450 : else
451 0 : wk_end = NULL;
452 :
453 : /*
454 : * Even if there's a match, we still need to check to make sure the suffix
455 : * takes up the entire path segment, to weed out constructions like
456 : * "/.well-known/openid-configuration-bad".
457 : */
458 0 : if (!wk_end || (*wk_end != '/' && *wk_end != '\0'))
459 : {
460 0 : libpq_append_conn_error(conn,
461 : "OAuth discovery URI \"%s\" uses an unsupported .well-known suffix",
462 : wkuri);
463 0 : return NULL;
464 : }
465 :
466 : /*
467 : * Finally, make sure the .well-known components are provided either as a
468 : * prefix (IETF style) or as a postfix (OIDC style). In other words,
469 : * "https://localhost/a/.well-known/openid-configuration/b" is not allowed
470 : * to claim association with "https://localhost/a/b".
471 : */
472 0 : if (*wk_end != '\0')
473 : {
474 : /*
475 : * It's not at the end, so it's required to be at the beginning at the
476 : * path. Find the starting slash.
477 : */
478 : const char *path_start;
479 :
480 0 : path_start = strchr(authority_start, '/');
481 : Assert(path_start); /* otherwise we wouldn't have found WK_PREFIX */
482 :
483 0 : if (wk_start != path_start)
484 : {
485 0 : libpq_append_conn_error(conn,
486 : "OAuth discovery URI \"%s\" uses an invalid format",
487 : wkuri);
488 0 : return NULL;
489 : }
490 : }
491 :
492 : /* Checks passed! Now build the issuer. */
493 0 : issuer = strdup(wkuri);
494 0 : if (!issuer)
495 : {
496 0 : libpq_append_conn_error(conn, "out of memory");
497 0 : return NULL;
498 : }
499 :
500 : /*
501 : * The .well-known components are from [wk_start, wk_end). Remove those to
502 : * form the issuer ID, by shifting the path suffix (which may be empty)
503 : * leftwards.
504 : */
505 0 : start_offset = wk_start - wkuri;
506 0 : end_offset = wk_end - wkuri;
507 0 : end_len = strlen(wk_end) + 1; /* move the NULL terminator too */
508 :
509 0 : memmove(issuer + start_offset, issuer + end_offset, end_len);
510 :
511 0 : return issuer;
512 : }
513 :
514 : /*
515 : * Parses the server error result (RFC 7628, Sec. 3.2.2) contained in msg and
516 : * stores any discovered openid_configuration and scope settings for the
517 : * connection.
518 : */
519 : static bool
520 0 : handle_oauth_sasl_error(PGconn *conn, const char *msg, int msglen)
521 : {
522 : JsonLexContext *lex;
523 0 : JsonSemAction sem = {0};
524 : JsonParseErrorType err;
525 0 : struct json_ctx ctx = {0};
526 0 : char *errmsg = NULL;
527 0 : bool success = false;
528 :
529 : Assert(conn->oauth_issuer_id); /* ensured by setup_oauth_parameters() */
530 :
531 : /* Sanity check. */
532 0 : if (strlen(msg) != msglen)
533 : {
534 0 : libpq_append_conn_error(conn,
535 : "server's error message contained an embedded NULL, and was discarded");
536 0 : return false;
537 : }
538 :
539 : /*
540 : * pg_parse_json doesn't validate the incoming UTF-8, so we have to check
541 : * that up front.
542 : */
543 0 : if (pg_encoding_verifymbstr(PG_UTF8, msg, msglen) != msglen)
544 : {
545 0 : libpq_append_conn_error(conn,
546 : "server's error response is not valid UTF-8");
547 0 : return false;
548 : }
549 :
550 0 : lex = makeJsonLexContextCstringLen(NULL, msg, msglen, PG_UTF8, true);
551 0 : setJsonLexContextOwnsTokens(lex, true); /* must not leak on error */
552 :
553 0 : initPQExpBuffer(&ctx.errbuf);
554 0 : sem.semstate = &ctx;
555 :
556 0 : sem.object_start = oauth_json_object_start;
557 0 : sem.object_end = oauth_json_object_end;
558 0 : sem.object_field_start = oauth_json_object_field_start;
559 0 : sem.array_start = oauth_json_array_start;
560 0 : sem.array_end = oauth_json_array_end;
561 0 : sem.scalar = oauth_json_scalar;
562 :
563 0 : err = pg_parse_json(lex, &sem);
564 :
565 0 : if (err == JSON_SEM_ACTION_FAILED)
566 : {
567 0 : if (PQExpBufferDataBroken(ctx.errbuf))
568 0 : errmsg = libpq_gettext("out of memory");
569 0 : else if (ctx.errmsg)
570 0 : errmsg = ctx.errmsg;
571 : else
572 : {
573 : /*
574 : * Developer error: one of the action callbacks didn't call
575 : * oauth_json_set_error() before erroring out.
576 : */
577 : Assert(oauth_json_has_error(&ctx));
578 0 : errmsg = "<unexpected empty error>";
579 : }
580 : }
581 0 : else if (err != JSON_SUCCESS)
582 0 : errmsg = json_errdetail(err, lex);
583 :
584 0 : if (errmsg)
585 0 : libpq_append_conn_error(conn,
586 : "failed to parse server's error response: %s",
587 : errmsg);
588 :
589 : /* Don't need the error buffer or the JSON lexer anymore. */
590 0 : termPQExpBuffer(&ctx.errbuf);
591 0 : freeJsonLexContext(lex);
592 :
593 0 : if (errmsg)
594 0 : goto cleanup;
595 :
596 0 : if (ctx.discovery_uri)
597 : {
598 : char *discovery_issuer;
599 :
600 : /*
601 : * The URI MUST correspond to our existing issuer, to avoid mix-ups.
602 : *
603 : * Issuer comparison is done byte-wise, rather than performing any URL
604 : * normalization; this follows the suggestions for issuer comparison
605 : * in RFC 9207 Sec. 2.4 (which requires simple string comparison) and
606 : * vastly simplifies things. Since this is the key protection against
607 : * a rogue server sending the client to an untrustworthy location,
608 : * simpler is better.
609 : */
610 0 : discovery_issuer = issuer_from_well_known_uri(conn, ctx.discovery_uri);
611 0 : if (!discovery_issuer)
612 0 : goto cleanup; /* error message already set */
613 :
614 0 : if (strcmp(conn->oauth_issuer_id, discovery_issuer) != 0)
615 : {
616 0 : libpq_append_conn_error(conn,
617 : "server's discovery document at %s (issuer \"%s\") is incompatible with oauth_issuer (%s)",
618 : ctx.discovery_uri, discovery_issuer,
619 : conn->oauth_issuer_id);
620 :
621 0 : free(discovery_issuer);
622 0 : goto cleanup;
623 : }
624 :
625 0 : free(discovery_issuer);
626 :
627 0 : if (!conn->oauth_discovery_uri)
628 : {
629 0 : conn->oauth_discovery_uri = ctx.discovery_uri;
630 0 : ctx.discovery_uri = NULL;
631 : }
632 : else
633 : {
634 : /* This must match the URI we'd previously determined. */
635 0 : if (strcmp(conn->oauth_discovery_uri, ctx.discovery_uri) != 0)
636 : {
637 0 : libpq_append_conn_error(conn,
638 : "server's discovery document has moved to %s (previous location was %s)",
639 : ctx.discovery_uri,
640 : conn->oauth_discovery_uri);
641 0 : goto cleanup;
642 : }
643 : }
644 : }
645 :
646 0 : if (ctx.scope)
647 : {
648 : /* Servers may not override a previously set oauth_scope. */
649 0 : if (!conn->oauth_scope)
650 : {
651 0 : conn->oauth_scope = ctx.scope;
652 0 : ctx.scope = NULL;
653 : }
654 : }
655 :
656 0 : if (!ctx.status)
657 : {
658 0 : libpq_append_conn_error(conn,
659 : "server sent error response without a status");
660 0 : goto cleanup;
661 : }
662 :
663 0 : if (strcmp(ctx.status, "invalid_token") != 0)
664 : {
665 : /*
666 : * invalid_token is the only error code we'll automatically retry for;
667 : * otherwise, just bail out now.
668 : */
669 0 : libpq_append_conn_error(conn,
670 : "server rejected OAuth bearer token: %s",
671 : ctx.status);
672 0 : goto cleanup;
673 : }
674 :
675 0 : success = true;
676 :
677 0 : cleanup:
678 0 : free(ctx.status);
679 0 : free(ctx.scope);
680 0 : free(ctx.discovery_uri);
681 :
682 0 : return success;
683 : }
684 :
685 : /*
686 : * Helper for handling flow failures. If anything was put into request->error,
687 : * it's added to conn->errorMessage here.
688 : */
689 : static void
690 0 : report_flow_error(PGconn *conn, const PGoauthBearerRequestV2 *request)
691 : {
692 0 : fe_oauth_state *state = conn->sasl_state;
693 0 : const char *errmsg = request->error;
694 :
695 : /*
696 : * User-defined flows are called out explicitly so that the user knows who
697 : * to blame. Builtin flows don't need that extra message length; we expect
698 : * them to always fill in request->error on failure anyway.
699 : */
700 0 : if (state->builtin)
701 : {
702 0 : if (!errmsg)
703 : {
704 : /*
705 : * Don't turn a bug here into a crash in production, but don't
706 : * bother translating either.
707 : */
708 : Assert(false);
709 0 : errmsg = "builtin flow failed but did not provide an error message";
710 : }
711 :
712 0 : appendPQExpBufferStr(&conn->errorMessage, errmsg);
713 : }
714 : else
715 : {
716 0 : appendPQExpBufferStr(&conn->errorMessage,
717 0 : libpq_gettext("user-defined OAuth flow failed"));
718 0 : if (errmsg)
719 : {
720 0 : appendPQExpBufferStr(&conn->errorMessage, ": ");
721 0 : appendPQExpBufferStr(&conn->errorMessage, errmsg);
722 : }
723 : }
724 :
725 0 : appendPQExpBufferChar(&conn->errorMessage, '\n');
726 0 : }
727 :
728 : /*
729 : * Callback implementation of conn->async_auth() for OAuth flows. Delegates the
730 : * retrieval of the token to the PGoauthBearerRequestV2.async() callback.
731 : *
732 : * This will be called multiple times as needed; the callback is responsible for
733 : * setting an altsock to signal and returning the correct PGRES_POLLING_*
734 : * statuses for use by PQconnectPoll().
735 : */
736 : static PostgresPollingStatusType
737 0 : run_oauth_flow(PGconn *conn)
738 : {
739 0 : fe_oauth_state *state = conn->sasl_state;
740 0 : PGoauthBearerRequestV2 *request = state->async_ctx;
741 : PostgresPollingStatusType status;
742 :
743 0 : if (!request->v1.async)
744 : {
745 : Assert(!state->builtin); /* be very noisy if our code does this */
746 0 : libpq_append_conn_error(conn,
747 : "user-defined OAuth flow provided neither a token nor an async callback");
748 0 : return PGRES_POLLING_FAILED;
749 : }
750 :
751 0 : status = do_async(state, request);
752 :
753 0 : if (status == PGRES_POLLING_FAILED)
754 : {
755 0 : report_flow_error(conn, request);
756 0 : return status;
757 : }
758 0 : else if (status == PGRES_POLLING_OK)
759 : {
760 : /*
761 : * We already have a token, so copy it into the conn. (We can't hold
762 : * onto the original string, since it may not be safe for us to free()
763 : * it.)
764 : */
765 0 : if (!request->v1.token)
766 : {
767 : Assert(!state->builtin);
768 0 : libpq_append_conn_error(conn,
769 : "user-defined OAuth flow did not provide a token");
770 0 : return PGRES_POLLING_FAILED;
771 : }
772 :
773 0 : conn->oauth_token = strdup(request->v1.token);
774 0 : if (!conn->oauth_token)
775 : {
776 0 : libpq_append_conn_error(conn, "out of memory");
777 0 : return PGRES_POLLING_FAILED;
778 : }
779 :
780 0 : return PGRES_POLLING_OK;
781 : }
782 :
783 : /* The hook wants the client to poll the altsock. Make sure it set one. */
784 0 : if (conn->altsock == PGINVALID_SOCKET)
785 : {
786 : Assert(!state->builtin);
787 0 : libpq_append_conn_error(conn,
788 : "user-defined OAuth flow did not provide a socket for polling");
789 0 : return PGRES_POLLING_FAILED;
790 : }
791 :
792 0 : return status;
793 : }
794 :
795 : /*
796 : * Cleanup callback for the async flow. Delegates most of its job to
797 : * PGoauthBearerRequest.cleanup(), then disconnects the altsock and frees the
798 : * request itself.
799 : *
800 : * This is called either at the end of a successful authentication, or during
801 : * pqDropConnection(), so we won't leak resources even if PQconnectPoll() never
802 : * calls us back.
803 : */
804 : static void
805 0 : cleanup_oauth_flow(PGconn *conn)
806 : {
807 0 : fe_oauth_state *state = conn->sasl_state;
808 0 : PGoauthBearerRequestV2 *request = state->async_ctx;
809 :
810 : Assert(request);
811 :
812 0 : do_cleanup(state, request);
813 0 : conn->altsock = PGINVALID_SOCKET;
814 :
815 0 : free(request);
816 0 : state->async_ctx = NULL;
817 0 : }
818 :
819 : /*-------------
820 : * Builtin Flow
821 : *
822 : * There are three potential implementations of use_builtin_flow:
823 : *
824 : * 1) If the OAuth client is disabled at configuration time, return zero.
825 : * Dependent clients must provide their own flow.
826 : * 2) If the OAuth client is enabled and USE_DYNAMIC_OAUTH is defined, dlopen()
827 : * the libpq-oauth plugin and use its implementation.
828 : * 3) Otherwise, use flow callbacks that are statically linked into the
829 : * executable.
830 : *
831 : * For caller convenience, the return value follows the convention of
832 : * PQauthDataHook: zero means no implementation is provided, negative indicates
833 : * failure, and positive indicates success.
834 : */
835 :
836 : #if !defined(USE_LIBCURL)
837 :
838 : /*
839 : * This configuration doesn't support the builtin flow.
840 : */
841 :
842 : static int
843 0 : use_builtin_flow(PGconn *conn, fe_oauth_state *state, PGoauthBearerRequestV2 *request)
844 : {
845 0 : return 0;
846 : }
847 :
848 : #elif defined(USE_DYNAMIC_OAUTH)
849 :
850 : /*
851 : * Use the builtin flow in the libpq-oauth plugin, which is loaded at runtime.
852 : */
853 :
854 : typedef char *(*libpq_gettext_func) (const char *msgid);
855 :
856 : /*
857 : * Loads the libpq-oauth plugin via dlopen(), initializes it, and plugs its
858 : * callbacks into the connection's async auth handlers.
859 : *
860 : * Failure to load here results in a relatively quiet connection error, to
861 : * handle the use case where the build supports loading a flow but a user does
862 : * not want to install it. Troubleshooting of linker/loader failures can be done
863 : * via PGOAUTHDEBUG.
864 : *
865 : * The lifetime of *request ends shortly after this call, so it must be copied
866 : * to longer-lived storage.
867 : */
868 : static int
869 : use_builtin_flow(PGconn *conn, fe_oauth_state *state, PGoauthBearerRequestV2 *request)
870 : {
871 : static bool initialized = false;
872 : static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER;
873 : int lockerr;
874 :
875 : void (*init) (libpq_gettext_func gettext_impl);
876 : int (*start_flow) (PGconn *conn, PGoauthBearerRequestV2 *request);
877 :
878 : /*
879 : * On macOS only, load the module using its absolute install path; the
880 : * standard search behavior is not very helpful for this use case. Unlike
881 : * on other platforms, DYLD_LIBRARY_PATH is used as a fallback even with
882 : * absolute paths (modulo SIP effects), so tests can continue to work.
883 : *
884 : * On the other platforms, load the module using only the basename, to
885 : * rely on the runtime linker's standard search behavior.
886 : */
887 : const char *const module_name =
888 : #if defined(__darwin__)
889 : LIBDIR "/libpq-oauth" DLSUFFIX;
890 : #else
891 : "libpq-oauth" DLSUFFIX;
892 : #endif
893 :
894 : state->flow_module = dlopen(module_name, RTLD_NOW | RTLD_LOCAL);
895 : if (!state->flow_module)
896 : {
897 : /*
898 : * For end users, this probably isn't an error condition, it just
899 : * means the flow isn't installed. Developers and package maintainers
900 : * may want to debug this via the PGOAUTHDEBUG envvar, though.
901 : *
902 : * Note that POSIX dlerror() isn't guaranteed to be threadsafe.
903 : */
904 : if (oauth_parse_debug_flags() & OAUTHDEBUG_PLUGIN_ERRORS)
905 : fprintf(stderr, "failed dlopen for libpq-oauth: %s\n", dlerror());
906 :
907 : return 0;
908 : }
909 :
910 : /*
911 : * Our libpq-oauth.so provides a special initialization function for libpq
912 : * integration. If we don't find this, assume that a custom module is in
913 : * use instead.
914 : */
915 : init = dlsym(state->flow_module, "libpq_oauth_init");
916 : if (!init)
917 : state->builtin = false; /* adjust our error messages */
918 :
919 : if ((start_flow = dlsym(state->flow_module, "pg_start_oauthbearer")) == NULL)
920 : {
921 : /*
922 : * This is more of an error condition than the one above, but the
923 : * cause is still locked behind PGOAUTHDEBUG due to the dlerror()
924 : * threadsafety issue.
925 : */
926 : if (oauth_parse_debug_flags() & OAUTHDEBUG_PLUGIN_ERRORS)
927 : fprintf(stderr, "failed dlsym for libpq-oauth: %s\n", dlerror());
928 :
929 : dlclose(state->flow_module);
930 : state->flow_module = NULL;
931 :
932 : request->error = libpq_gettext("could not find entry point for libpq-oauth");
933 : return -1;
934 : }
935 :
936 : /*
937 : * Past this point, we do not unload the module. It stays in the process
938 : * permanently.
939 : */
940 :
941 : if (init)
942 : {
943 : /*
944 : * We need to inject necessary function pointers into the module. This
945 : * only needs to be done once -- even if the pointers are constant,
946 : * assigning them while another thread is executing the flows feels
947 : * like tempting fate.
948 : */
949 : if ((lockerr = pthread_mutex_lock(&init_mutex)) != 0)
950 : {
951 : /* Should not happen... but don't continue if it does. */
952 : Assert(false);
953 :
954 : appendPQExpBuffer(&conn->errorMessage,
955 : "use_builtin_flow: failed to lock mutex (%d)\n",
956 : lockerr);
957 :
958 : request->error = ""; /* satisfy report_flow_error() */
959 : return -1;
960 : }
961 :
962 : if (!initialized)
963 : {
964 : init(
965 : #ifdef ENABLE_NLS
966 : libpq_gettext
967 : #else
968 : NULL
969 : #endif
970 : );
971 :
972 : initialized = true;
973 : }
974 :
975 : pthread_mutex_unlock(&init_mutex);
976 : }
977 :
978 : return (start_flow(conn, request) == 0) ? 1 : -1;
979 : }
980 :
981 : #else
982 :
983 : /*
984 : * For static builds, we can just call pg_start_oauthbearer() directly. It's
985 : * provided by libpq-oauth.a.
986 : */
987 :
988 : extern int pg_start_oauthbearer(PGconn *conn, PGoauthBearerRequestV2 *request);
989 :
990 : static int
991 : use_builtin_flow(PGconn *conn, fe_oauth_state *state, PGoauthBearerRequestV2 *request)
992 : {
993 : return (pg_start_oauthbearer(conn, request) == 0) ? 1 : -1;
994 : }
995 :
996 : #endif /* USE_LIBCURL */
997 :
998 :
999 : /*
1000 : * Chooses an OAuth client flow for the connection, which will retrieve a Bearer
1001 : * token for presentation to the server.
1002 : *
1003 : * If the application has registered a custom flow handler using
1004 : * PQAUTHDATA_OAUTH_BEARER_TOKEN[_V2], it may either return a token immediately
1005 : * (e.g. if it has one cached for immediate use), or set up for a series of
1006 : * asynchronous callbacks which will be managed by run_oauth_flow().
1007 : *
1008 : * If the default handler is used instead, a Device Authorization flow is used
1009 : * for the connection if support has been compiled in. (See oauth-curl.c for
1010 : * implementation details.)
1011 : *
1012 : * If neither a custom handler nor the builtin flow is available, the connection
1013 : * fails here.
1014 : */
1015 : static bool
1016 0 : setup_token_request(PGconn *conn, fe_oauth_state *state)
1017 : {
1018 : int res;
1019 0 : PGoauthBearerRequestV2 request = {
1020 : .v1 = {
1021 0 : .openid_configuration = conn->oauth_discovery_uri,
1022 0 : .scope = conn->oauth_scope,
1023 : },
1024 0 : .issuer = conn->oauth_issuer_id,
1025 : };
1026 :
1027 : Assert(request.v1.openid_configuration);
1028 : Assert(request.issuer);
1029 :
1030 : /*
1031 : * The client may have overridden the OAuth flow. Try the v2 hook first,
1032 : * then fall back to the v1 implementation. If neither is available, try
1033 : * the builtin flow.
1034 : */
1035 0 : res = PQauthDataHook(PQAUTHDATA_OAUTH_BEARER_TOKEN_V2, conn, &request);
1036 0 : if (res == 0)
1037 : {
1038 0 : poison_req_v2(&request, true);
1039 :
1040 0 : res = PQauthDataHook(PQAUTHDATA_OAUTH_BEARER_TOKEN, conn, &request);
1041 0 : state->v1 = (res != 0);
1042 :
1043 0 : poison_req_v2(&request, false);
1044 : }
1045 0 : if (res == 0)
1046 : {
1047 0 : state->builtin = true;
1048 0 : res = use_builtin_flow(conn, state, &request);
1049 : }
1050 :
1051 0 : if (res > 0)
1052 : {
1053 : PGoauthBearerRequestV2 *request_copy;
1054 :
1055 0 : if (request.v1.token)
1056 : {
1057 : /*
1058 : * We already have a token, so copy it into the conn. (We can't
1059 : * hold onto the original string, since it may not be safe for us
1060 : * to free() it.)
1061 : */
1062 0 : conn->oauth_token = strdup(request.v1.token);
1063 0 : if (!conn->oauth_token)
1064 : {
1065 0 : libpq_append_conn_error(conn, "out of memory");
1066 0 : goto fail;
1067 : }
1068 :
1069 : /* short-circuit */
1070 0 : do_cleanup(state, &request);
1071 0 : return true;
1072 : }
1073 :
1074 0 : request_copy = malloc(sizeof(*request_copy));
1075 0 : if (!request_copy)
1076 : {
1077 0 : libpq_append_conn_error(conn, "out of memory");
1078 0 : goto fail;
1079 : }
1080 :
1081 0 : *request_copy = request;
1082 :
1083 0 : conn->async_auth = run_oauth_flow;
1084 0 : conn->cleanup_async_auth = cleanup_oauth_flow;
1085 0 : state->async_ctx = request_copy;
1086 :
1087 0 : return true;
1088 : }
1089 :
1090 : /*
1091 : * Failure cases: either we tried to set up a flow and failed, or there
1092 : * was no flow to try.
1093 : */
1094 0 : if (res < 0)
1095 0 : report_flow_error(conn, &request);
1096 : else
1097 0 : libpq_append_conn_error(conn, "no OAuth flows are available (try installing the libpq-oauth package)");
1098 :
1099 0 : fail:
1100 0 : do_cleanup(state, &request);
1101 0 : return false;
1102 : }
1103 :
1104 : /*
1105 : * Fill in our issuer identifier (and discovery URI, if possible) using the
1106 : * connection parameters. If conn->oauth_discovery_uri can't be populated in
1107 : * this function, it will be requested from the server.
1108 : */
1109 : static bool
1110 0 : setup_oauth_parameters(PGconn *conn)
1111 : {
1112 : /*
1113 : * This is the only function that sets conn->oauth_issuer_id. If a
1114 : * previous connection attempt has already computed it, don't overwrite it
1115 : * or the discovery URI. (There's no reason for them to change once
1116 : * they're set, and handle_oauth_sasl_error() will fail the connection if
1117 : * the server attempts to switch them on us later.)
1118 : */
1119 0 : if (conn->oauth_issuer_id)
1120 0 : return true;
1121 :
1122 : /*---
1123 : * To talk to a server, we require the user to provide issuer and client
1124 : * identifiers.
1125 : *
1126 : * While it's possible for an OAuth client to support multiple issuers, it
1127 : * requires additional effort to make sure the flows in use are safe -- to
1128 : * quote RFC 9207,
1129 : *
1130 : * OAuth clients that interact with only one authorization server are
1131 : * not vulnerable to mix-up attacks. However, when such clients decide
1132 : * to add support for a second authorization server in the future, they
1133 : * become vulnerable and need to apply countermeasures to mix-up
1134 : * attacks.
1135 : *
1136 : * For now, we allow only one.
1137 : */
1138 0 : if (!conn->oauth_issuer || !conn->oauth_client_id)
1139 : {
1140 0 : libpq_append_conn_error(conn,
1141 : "server requires OAuth authentication, but oauth_issuer and oauth_client_id are not both set");
1142 0 : return false;
1143 : }
1144 :
1145 : /*
1146 : * oauth_issuer is interpreted differently if it's a well-known discovery
1147 : * URI rather than just an issuer identifier.
1148 : */
1149 0 : if (strstr(conn->oauth_issuer, WK_PREFIX) != NULL)
1150 : {
1151 : /*
1152 : * Convert the URI back to an issuer identifier. (This also performs
1153 : * validation of the URI format.)
1154 : */
1155 0 : conn->oauth_issuer_id = issuer_from_well_known_uri(conn,
1156 0 : conn->oauth_issuer);
1157 0 : if (!conn->oauth_issuer_id)
1158 0 : return false; /* error message already set */
1159 :
1160 0 : conn->oauth_discovery_uri = strdup(conn->oauth_issuer);
1161 0 : if (!conn->oauth_discovery_uri)
1162 : {
1163 0 : libpq_append_conn_error(conn, "out of memory");
1164 0 : return false;
1165 : }
1166 : }
1167 : else
1168 : {
1169 : /*
1170 : * Treat oauth_issuer as an issuer identifier. We'll ask the server
1171 : * for the discovery URI.
1172 : */
1173 0 : conn->oauth_issuer_id = strdup(conn->oauth_issuer);
1174 0 : if (!conn->oauth_issuer_id)
1175 : {
1176 0 : libpq_append_conn_error(conn, "out of memory");
1177 0 : return false;
1178 : }
1179 : }
1180 :
1181 0 : return true;
1182 : }
1183 :
1184 : /*
1185 : * Implements the OAUTHBEARER SASL exchange (RFC 7628, Sec. 3.2).
1186 : *
1187 : * If the necessary OAuth parameters are set up on the connection, this will run
1188 : * the client flow asynchronously and present the resulting token to the server.
1189 : * Otherwise, an empty discovery response will be sent and any parameters sent
1190 : * back by the server will be stored for a second attempt.
1191 : *
1192 : * For a full description of the API, see libpq/sasl.h.
1193 : */
1194 : static SASLStatus
1195 0 : oauth_exchange(void *opaq, bool final,
1196 : char *input, int inputlen,
1197 : char **output, int *outputlen)
1198 : {
1199 0 : fe_oauth_state *state = opaq;
1200 0 : PGconn *conn = state->conn;
1201 0 : bool discover = false;
1202 :
1203 0 : *output = NULL;
1204 0 : *outputlen = 0;
1205 :
1206 0 : switch (state->step)
1207 : {
1208 0 : case FE_OAUTH_INIT:
1209 : /* We begin in the initial response phase. */
1210 : Assert(inputlen == -1);
1211 :
1212 0 : if (!setup_oauth_parameters(conn))
1213 0 : return SASL_FAILED;
1214 :
1215 0 : if (conn->oauth_token)
1216 : {
1217 : /*
1218 : * A previous connection already fetched the token; we'll use
1219 : * it below.
1220 : */
1221 : }
1222 0 : else if (conn->oauth_discovery_uri)
1223 : {
1224 : /*
1225 : * We don't have a token, but we have a discovery URI already
1226 : * stored. Decide whether we're using a user-provided OAuth
1227 : * flow or the one we have built in.
1228 : */
1229 0 : if (!setup_token_request(conn, state))
1230 0 : return SASL_FAILED;
1231 :
1232 0 : if (conn->oauth_token)
1233 : {
1234 : /*
1235 : * A really smart user implementation may have already
1236 : * given us the token (e.g. if there was an unexpired copy
1237 : * already cached), and we can use it immediately.
1238 : */
1239 : }
1240 : else
1241 : {
1242 : /*
1243 : * Otherwise, we'll have to hand the connection over to
1244 : * our OAuth implementation.
1245 : *
1246 : * This could take a while, since it generally involves a
1247 : * user in the loop. To avoid consuming the server's
1248 : * authentication timeout, we'll continue this handshake
1249 : * to the end, so that the server can close its side of
1250 : * the connection. We'll open a second connection later
1251 : * once we've retrieved a token.
1252 : */
1253 0 : discover = true;
1254 : }
1255 : }
1256 : else
1257 : {
1258 : /*
1259 : * If we don't have a token, and we don't have a discovery URI
1260 : * to be able to request a token, we ask the server for one
1261 : * explicitly.
1262 : */
1263 0 : discover = true;
1264 : }
1265 :
1266 : /*
1267 : * Generate an initial response. This either contains a token, if
1268 : * we have one, or an empty discovery response which is doomed to
1269 : * fail.
1270 : */
1271 0 : *output = client_initial_response(conn, discover);
1272 0 : if (!*output)
1273 0 : return SASL_FAILED;
1274 :
1275 0 : *outputlen = strlen(*output);
1276 0 : state->step = FE_OAUTH_BEARER_SENT;
1277 :
1278 0 : if (conn->oauth_token)
1279 : {
1280 : /*
1281 : * For the purposes of require_auth, our side of
1282 : * authentication is done at this point; the server will
1283 : * either accept the connection or send an error. Unlike
1284 : * SCRAM, there is no additional server data to check upon
1285 : * success.
1286 : */
1287 0 : conn->client_finished_auth = true;
1288 : }
1289 :
1290 0 : return SASL_CONTINUE;
1291 :
1292 0 : case FE_OAUTH_BEARER_SENT:
1293 0 : if (final)
1294 : {
1295 : /*
1296 : * OAUTHBEARER does not make use of additional data with a
1297 : * successful SASL exchange, so we shouldn't get an
1298 : * AuthenticationSASLFinal message.
1299 : */
1300 0 : libpq_append_conn_error(conn,
1301 : "server sent unexpected additional OAuth data");
1302 0 : return SASL_FAILED;
1303 : }
1304 :
1305 : /*
1306 : * An error message was sent by the server. Respond with the
1307 : * required dummy message (RFC 7628, sec. 3.2.3).
1308 : */
1309 0 : *output = strdup(kvsep);
1310 0 : if (unlikely(!*output))
1311 : {
1312 0 : libpq_append_conn_error(conn, "out of memory");
1313 0 : return SASL_FAILED;
1314 : }
1315 0 : *outputlen = strlen(*output); /* == 1 */
1316 :
1317 : /* Grab the settings from discovery. */
1318 0 : if (!handle_oauth_sasl_error(conn, input, inputlen))
1319 0 : return SASL_FAILED;
1320 :
1321 0 : if (conn->oauth_token)
1322 : {
1323 : /*
1324 : * The server rejected our token. Continue onwards towards the
1325 : * expected FATAL message, but mark our state to catch any
1326 : * unexpected "success" from the server.
1327 : */
1328 0 : state->step = FE_OAUTH_SERVER_ERROR;
1329 0 : return SASL_CONTINUE;
1330 : }
1331 :
1332 0 : if (!conn->async_auth)
1333 : {
1334 : /*
1335 : * No OAuth flow is set up yet. Did we get enough information
1336 : * from the server to create one?
1337 : */
1338 0 : if (!conn->oauth_discovery_uri)
1339 : {
1340 0 : libpq_append_conn_error(conn,
1341 : "server requires OAuth authentication, but no discovery metadata was provided");
1342 0 : return SASL_FAILED;
1343 : }
1344 :
1345 : /* Yes. Set up the flow now. */
1346 0 : if (!setup_token_request(conn, state))
1347 0 : return SASL_FAILED;
1348 :
1349 0 : if (conn->oauth_token)
1350 : {
1351 : /*
1352 : * A token was available in a custom flow's cache. Skip
1353 : * the asynchronous processing.
1354 : */
1355 0 : goto reconnect;
1356 : }
1357 : }
1358 :
1359 : /*
1360 : * Time to retrieve a token. This involves a number of HTTP
1361 : * connections and timed waits, so we escape the synchronous auth
1362 : * processing and tell PQconnectPoll to transfer control to our
1363 : * async implementation.
1364 : */
1365 : Assert(conn->async_auth); /* should have been set already */
1366 0 : state->step = FE_OAUTH_REQUESTING_TOKEN;
1367 0 : return SASL_ASYNC;
1368 :
1369 0 : case FE_OAUTH_REQUESTING_TOKEN:
1370 :
1371 : /*
1372 : * We've returned successfully from token retrieval. Double-check
1373 : * that we have what we need for the next connection.
1374 : */
1375 0 : if (!conn->oauth_token)
1376 : {
1377 : Assert(false); /* should have failed before this point! */
1378 0 : libpq_append_conn_error(conn,
1379 : "internal error: OAuth flow did not set a token");
1380 0 : return SASL_FAILED;
1381 : }
1382 :
1383 0 : goto reconnect;
1384 :
1385 0 : case FE_OAUTH_SERVER_ERROR:
1386 :
1387 : /*
1388 : * After an error, the server should send an error response to
1389 : * fail the SASL handshake, which is handled in higher layers.
1390 : *
1391 : * If we get here, the server either sent *another* challenge
1392 : * which isn't defined in the RFC, or completed the handshake
1393 : * successfully after telling us it was going to fail. Neither is
1394 : * acceptable.
1395 : */
1396 0 : libpq_append_conn_error(conn,
1397 : "server sent additional OAuth data after error");
1398 0 : return SASL_FAILED;
1399 :
1400 0 : default:
1401 0 : libpq_append_conn_error(conn, "invalid OAuth exchange state");
1402 0 : break;
1403 : }
1404 :
1405 : Assert(false); /* should never get here */
1406 0 : return SASL_FAILED;
1407 :
1408 0 : reconnect:
1409 :
1410 : /*
1411 : * Despite being a failure from the point of view of SASL, we have enough
1412 : * information to restart with a new connection.
1413 : */
1414 0 : libpq_append_conn_error(conn, "retrying connection with new bearer token");
1415 0 : conn->oauth_want_retry = true;
1416 0 : return SASL_FAILED;
1417 : }
1418 :
1419 : static bool
1420 0 : oauth_channel_bound(void *opaq)
1421 : {
1422 : /* This mechanism does not support channel binding. */
1423 0 : return false;
1424 : }
1425 :
1426 : /*
1427 : * Fully clears out any stored OAuth token. This is done proactively upon
1428 : * successful connection as well as during pqClosePGconn().
1429 : */
1430 : void
1431 30764 : pqClearOAuthToken(PGconn *conn)
1432 : {
1433 30764 : if (!conn->oauth_token)
1434 30764 : return;
1435 :
1436 0 : explicit_bzero(conn->oauth_token, strlen(conn->oauth_token));
1437 0 : free(conn->oauth_token);
1438 0 : conn->oauth_token = NULL;
1439 : }
1440 :
1441 : /*
1442 : * Hook v1 Poisoning
1443 : *
1444 : * Try to catch misuses of the v1 PQAUTHDATA_OAUTH_BEARER_TOKEN hook and its
1445 : * callbacks, which are not allowed to downcast their request argument to
1446 : * PGoauthBearerRequestV2. (Such clients may crash or worse when speaking to
1447 : * libpq 18.)
1448 : *
1449 : * This attempts to use Valgrind hooks, if present, to mark the extra members as
1450 : * inaccessible. For uninstrumented builds, it also munges request->issuer to
1451 : * try to crash clients that perform string operations, and it aborts if
1452 : * request->error is set.
1453 : */
1454 :
1455 : #define MASK_BITS ((uintptr_t) 0x55aa55aa55aa55aa)
1456 : #define POISON_MASK(ptr) ((void *) (((uintptr_t) ptr) ^ MASK_BITS))
1457 :
1458 : /*
1459 : * Workhorse for v2 request poisoning. This must be called exactly twice: once
1460 : * to poison, once to unpoison.
1461 : *
1462 : * NB: Unpoisoning must restore the request to its original state, because we
1463 : * might still switch back to a v2 implementation internally. Don't do anything
1464 : * destructive during the poison operation.
1465 : */
1466 : static void
1467 0 : poison_req_v2(PGoauthBearerRequestV2 *request, bool poison)
1468 : {
1469 : #ifdef USE_VALGRIND
1470 : void *const base = (char *) request + sizeof(request->v1);
1471 : const size_t len = sizeof(*request) - sizeof(request->v1);
1472 : #endif
1473 :
1474 0 : if (poison)
1475 : {
1476 : /* Poison request->issuer with a mask to help uninstrumented builds. */
1477 0 : request->issuer = POISON_MASK(request->issuer);
1478 :
1479 : /*
1480 : * We'll check to make sure request->error wasn't assigned when
1481 : * unpoisoning, so it had better not be assigned now.
1482 : */
1483 : Assert(!request->error);
1484 :
1485 : VALGRIND_MAKE_MEM_NOACCESS(base, len);
1486 : }
1487 : else
1488 : {
1489 : /*
1490 : * XXX Using DEFINED here is technically too lax; we might catch
1491 : * struct padding in the blast radius. But since this API has to
1492 : * poison stack addresses, and Valgrind can't track/manage undefined
1493 : * stack regions, we can't be any stricter without tracking the
1494 : * original state of the memory.
1495 : */
1496 : VALGRIND_MAKE_MEM_DEFINED(base, len);
1497 :
1498 : /* Undo our mask. */
1499 0 : request->issuer = POISON_MASK(request->issuer);
1500 :
1501 : /*
1502 : * For uninstrumented builds, make sure request->error wasn't touched.
1503 : */
1504 0 : if (request->error)
1505 : {
1506 0 : fprintf(stderr,
1507 : "abort! out-of-bounds write to PGoauthBearerRequest by PQAUTHDATA_OAUTH_BEARER_TOKEN hook\n");
1508 0 : abort();
1509 : }
1510 : }
1511 0 : }
1512 :
1513 : /*
1514 : * Wrapper around PGoauthBearerRequest.async() which applies poison during the
1515 : * callback when necessary.
1516 : */
1517 : static PostgresPollingStatusType
1518 0 : do_async(fe_oauth_state *state, PGoauthBearerRequestV2 *request)
1519 : {
1520 : PostgresPollingStatusType ret;
1521 0 : PGconn *conn = state->conn;
1522 :
1523 : Assert(request->v1.async);
1524 :
1525 0 : if (state->v1)
1526 0 : poison_req_v2(request, true);
1527 :
1528 0 : ret = request->v1.async(conn,
1529 : (PGoauthBearerRequest *) request,
1530 0 : &conn->altsock);
1531 :
1532 0 : if (state->v1)
1533 0 : poison_req_v2(request, false);
1534 :
1535 0 : return ret;
1536 : }
1537 :
1538 : /*
1539 : * Similar wrapper for the optional PGoauthBearerRequest.cleanup() callback.
1540 : * Does nothing if one is not defined.
1541 : */
1542 : static void
1543 0 : do_cleanup(fe_oauth_state *state, PGoauthBearerRequestV2 *request)
1544 : {
1545 0 : if (!request->v1.cleanup)
1546 0 : return;
1547 :
1548 0 : if (state->v1)
1549 0 : poison_req_v2(request, true);
1550 :
1551 0 : request->v1.cleanup(state->conn, (PGoauthBearerRequest *) request);
1552 :
1553 0 : if (state->v1)
1554 0 : poison_req_v2(request, false);
1555 : }
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