From 66e94448abec3aad04faf0a79cab4881ae08e08a Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Mon, 5 Aug 2024 06:05:33 -0700 Subject: [PATCH] Restrict accesses to non-system views and foreign tables during pg_dump. When pg_dump retrieves the list of database objects and performs the data dump, there was possibility that objects are replaced with others of the same name, such as views, and access them. This vulnerability could result in code execution with superuser privileges during the pg_dump process. This issue can arise when dumping data of sequences, foreign tables (only 13 or later), or tables registered with a WHERE clause in the extension configuration table. To address this, pg_dump now utilizes the newly introduced restrict_nonsystem_relation_kind GUC parameter to restrict the accesses to non-system views and foreign tables during the dump process. This new GUC parameter is added to back branches too, but these changes do not require cluster recreation. Back-patch to all supported branches. Reviewed-by: Noah Misch Security: CVE-2024-7348 Backpatch-through: 12 --- .../postgres_fdw/expected/postgres_fdw.out | 11 ++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 8 +++ doc/src/sgml/config.sgml | 17 +++++ doc/src/sgml/ref/pg_dump.sgml | 8 +++ src/backend/foreign/foreign.c | 10 +++ src/backend/optimizer/plan/createplan.c | 13 ++++ src/backend/optimizer/util/plancat.c | 12 ++++ src/backend/rewrite/rewriteHandler.c | 17 +++++ src/backend/tcop/postgres.c | 64 +++++++++++++++++++ src/backend/utils/misc/guc_tables.c | 12 ++++ src/bin/pg_dump/pg_dump.c | 47 ++++++++++++++ src/include/tcop/tcopprot.h | 6 ++ src/include/utils/guc_hooks.h | 3 + src/test/regress/expected/create_view.out | 19 +++++- src/test/regress/sql/create_view.sql | 9 +++ 15 files changed, 255 insertions(+), 1 deletion(-) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 212434711e..f3eb055e2c 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -637,6 +637,17 @@ EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft_empty ORDER BY c1; Remote SQL: SELECT c1, c2 FROM public.loct_empty ORDER BY c1 ASC NULLS LAST (3 rows) +-- test restriction on non-system foreign tables. +SET restrict_nonsystem_relation_kind TO 'foreign-table'; +SELECT * from ft1 where c1 < 1; -- ERROR +ERROR: access to non-system foreign table is restricted +INSERT INTO ft1 (c1) VALUES (1); -- ERROR +ERROR: access to non-system foreign table is restricted +DELETE FROM ft1 WHERE c1 = 1; -- ERROR +ERROR: access to non-system foreign table is restricted +TRUNCATE ft1; -- ERROR +ERROR: access to non-system foreign table is restricted +RESET restrict_nonsystem_relation_kind; -- =================================================================== -- WHERE with remotely-executable conditions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 371e131933..0734716ad9 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -327,6 +327,14 @@ DELETE FROM loct_empty; ANALYZE ft_empty; EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft_empty ORDER BY c1; +-- test restriction on non-system foreign tables. +SET restrict_nonsystem_relation_kind TO 'foreign-table'; +SELECT * from ft1 where c1 < 1; -- ERROR +INSERT INTO ft1 (c1) VALUES (1); -- ERROR +DELETE FROM ft1 WHERE c1 = 1; -- ERROR +TRUNCATE ft1; -- ERROR +RESET restrict_nonsystem_relation_kind; + -- =================================================================== -- WHERE with remotely-executable conditions -- =================================================================== diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index a65839a670..a1a1d58a43 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -9813,6 +9813,23 @@ SET XML OPTION { DOCUMENT | CONTENT }; + + restrict_nonsystem_relation_kind (string) + + restrict_nonsystem_relation_kind + configuration parameter + + + + + This variable specifies relation kind to which access is restricted. + It contains a comma-separated list of relation kind. Currently, the + supported relation kinds are view and + foreign-table. + + + + diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml index 1010d817f1..ffc29b04fb 100644 --- a/doc/src/sgml/ref/pg_dump.sgml +++ b/doc/src/sgml/ref/pg_dump.sgml @@ -1001,6 +1001,14 @@ PostgreSQL documentation The only exception is that an empty pattern is disallowed. + + + Using wildcards in may result + in access to unexpected foreign servers. Also, to use this option securely, + make sure that the named server must have a trusted owner. + + + When is specified, diff --git a/src/backend/foreign/foreign.c b/src/backend/foreign/foreign.c index f4f35728b4..bb67d9f92b 100644 --- a/src/backend/foreign/foreign.c +++ b/src/backend/foreign/foreign.c @@ -22,6 +22,7 @@ #include "foreign/foreign.h" #include "funcapi.h" #include "miscadmin.h" +#include "tcop/tcopprot.h" #include "utils/builtins.h" #include "utils/memutils.h" #include "utils/rel.h" @@ -326,6 +327,15 @@ GetFdwRoutine(Oid fdwhandler) Datum datum; FdwRoutine *routine; + /* Check if the access to foreign tables is restricted */ + if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_FOREIGN_TABLE) != 0)) + { + /* there must not be built-in FDW handler */ + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("access to non-system foreign table is restricted"))); + } + datum = OidFunctionCall0(fdwhandler); routine = (FdwRoutine *) DatumGetPointer(datum); diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index fe5a323cfd..c6d18ae00f 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -41,6 +41,7 @@ #include "parser/parse_clause.h" #include "parser/parsetree.h" #include "partitioning/partprune.h" +#include "tcop/tcopprot.h" #include "utils/lsyscache.h" @@ -7136,7 +7137,19 @@ make_modifytable(PlannerInfo *root, Plan *subplan, if (rte->rtekind == RTE_RELATION && rte->relkind == RELKIND_FOREIGN_TABLE) + { + /* Check if the access to foreign tables is restricted */ + if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_FOREIGN_TABLE) != 0)) + { + /* there must not be built-in foreign tables */ + Assert(rte->relid >= FirstNormalObjectId); + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("access to non-system foreign table is restricted"))); + } + fdwroutine = GetFdwRoutineByRelId(rte->relid); + } else fdwroutine = NULL; } diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index 9efdd844aa..78a3cfafde 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -45,6 +45,7 @@ #include "rewrite/rewriteManip.h" #include "statistics/statistics.h" #include "storage/bufmgr.h" +#include "tcop/tcopprot.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/partcache.h" @@ -528,6 +529,17 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent, /* Grab foreign-table info using the relcache, while we have it */ if (relation->rd_rel->relkind == RELKIND_FOREIGN_TABLE) { + /* Check if the access to foreign tables is restricted */ + if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_FOREIGN_TABLE) != 0)) + { + /* there must not be built-in foreign tables */ + Assert(RelationGetRelid(relation) >= FirstNormalObjectId); + + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("access to non-system foreign table is restricted"))); + } + rel->serverid = GetForeignServerIdByRelId(RelationGetRelid(relation)); rel->fdwroutine = GetFdwRoutineForRelation(relation, true); } diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c index e1d805d113..c223a2c50a 100644 --- a/src/backend/rewrite/rewriteHandler.c +++ b/src/backend/rewrite/rewriteHandler.c @@ -40,6 +40,7 @@ #include "rewrite/rewriteManip.h" #include "rewrite/rewriteSearchCycle.h" #include "rewrite/rowsecurity.h" +#include "tcop/tcopprot.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/rel.h" @@ -1729,6 +1730,14 @@ ApplyRetrieveRule(Query *parsetree, if (rule->qual != NULL) elog(ERROR, "cannot handle qualified ON SELECT rule"); + /* Check if the expansion of non-system views are restricted */ + if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 && + RelationGetRelid(relation) >= FirstNormalObjectId)) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("access to non-system view \"%s\" is restricted", + RelationGetRelationName(relation)))); + if (rt_index == parsetree->resultRelation) { /* @@ -3212,6 +3221,14 @@ rewriteTargetView(Query *parsetree, Relation view) } } + /* Check if the expansion of non-system views are restricted */ + if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 && + RelationGetRelid(view) >= FirstNormalObjectId)) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("access to non-system view \"%s\" is restricted", + RelationGetRelationName(view)))); + /* * The view must be updatable, else fail. * diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 4e4d06ba3a..8bc6bea113 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -79,6 +79,7 @@ #include "utils/snapmgr.h" #include "utils/timeout.h" #include "utils/timestamp.h" +#include "utils/varlena.h" /* ---------------- * global variables @@ -103,6 +104,9 @@ int PostAuthDelay = 0; /* Time between checks that the client is still connected. */ int client_connection_check_interval = 0; +/* flags for non-system relation kinds to restrict use */ +int restrict_nonsystem_relation_kind; + /* ---------------- * private typedefs etc * ---------------- @@ -3673,6 +3677,66 @@ assign_transaction_timeout(int newval, void *extra) } } +/* + * GUC check_hook for restrict_nonsystem_relation_kind + */ +bool +check_restrict_nonsystem_relation_kind(char **newval, void **extra, GucSource source) +{ + char *rawstring; + List *elemlist; + ListCell *l; + int flags = 0; + + /* Need a modifiable copy of string */ + rawstring = pstrdup(*newval); + + if (!SplitIdentifierString(rawstring, ',', &elemlist)) + { + /* syntax error in list */ + GUC_check_errdetail("List syntax is invalid."); + pfree(rawstring); + list_free(elemlist); + return false; + } + + foreach(l, elemlist) + { + char *tok = (char *) lfirst(l); + + if (pg_strcasecmp(tok, "view") == 0) + flags |= RESTRICT_RELKIND_VIEW; + else if (pg_strcasecmp(tok, "foreign-table") == 0) + flags |= RESTRICT_RELKIND_FOREIGN_TABLE; + else + { + GUC_check_errdetail("Unrecognized key word: \"%s\".", tok); + pfree(rawstring); + list_free(elemlist); + return false; + } + } + + pfree(rawstring); + list_free(elemlist); + + /* Save the flags in *extra, for use by the assign function */ + *extra = guc_malloc(ERROR, sizeof(int)); + *((int *) *extra) = flags; + + return true; +} + +/* + * GUC assign_hook for restrict_nonsystem_relation_kind + */ +void +assign_restrict_nonsystem_relation_kind(const char *newval, void *extra) +{ + int *flags = (int *) extra; + + restrict_nonsystem_relation_kind = *flags; +} /* * set_debug_options --- apply "-d N" command line option diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 74a38bb245..c0a52cdcc3 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -576,6 +576,7 @@ static char *server_encoding_string; static char *server_version_string; static int server_version_num; static char *debug_io_direct_string; +static char *restrict_nonsystem_relation_kind_string; #ifdef HAVE_SYSLOG #define DEFAULT_SYSLOG_FACILITY LOG_LOCAL0 @@ -4768,6 +4769,17 @@ struct config_string ConfigureNamesString[] = check_synchronized_standby_slots, assign_synchronized_standby_slots, NULL }, + { + {"restrict_nonsystem_relation_kind", PGC_USERSET, CLIENT_CONN_STATEMENT, + gettext_noop("Sets relation kinds of non-system relation to restrict use"), + NULL, + GUC_LIST_INPUT | GUC_NOT_IN_SAMPLE + }, + &restrict_nonsystem_relation_kind_string, + "", + check_restrict_nonsystem_relation_kind, assign_restrict_nonsystem_relation_kind, NULL + }, + /* End-of-list marker */ { {NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c index 79190470f7..b6e01d3d29 100644 --- a/src/bin/pg_dump/pg_dump.c +++ b/src/bin/pg_dump/pg_dump.c @@ -390,6 +390,7 @@ static bool nonemptyReloptions(const char *reloptions); static void appendReloptionsArrayAH(PQExpBuffer buffer, const char *reloptions, const char *prefix, Archive *fout); static char *get_synchronized_snapshot(Archive *fout); +static void set_restrict_relation_kind(Archive *AH, const char *value); static void setupDumpWorker(Archive *AH); static TableInfo *getRootTableInfo(const TableInfo *tbinfo); static bool forcePartitionRootLoad(const TableInfo *tbinfo); @@ -1354,6 +1355,13 @@ setup_connection(Archive *AH, const char *dumpencoding, ExecuteSqlStatement(AH, "SET row_security = off"); } + /* + * For security reasons, we restrict the expansion of non-system views and + * access to foreign tables during the pg_dump process. This restriction + * is adjusted when dumping foreign table data. + */ + set_restrict_relation_kind(AH, "view, foreign-table"); + /* * Initialize prepared-query state to "nothing prepared". We do this here * so that a parallel dump worker will have its own state. @@ -2222,6 +2230,10 @@ dumpTableData_copy(Archive *fout, const void *dcontext) */ if (tdinfo->filtercond || tbinfo->relkind == RELKIND_FOREIGN_TABLE) { + /* Temporary allows to access to foreign tables to dump data */ + if (tbinfo->relkind == RELKIND_FOREIGN_TABLE) + set_restrict_relation_kind(fout, "view"); + appendPQExpBufferStr(q, "COPY (SELECT "); /* klugery to get rid of parens in column list */ if (strlen(column_list) > 2) @@ -2333,6 +2345,11 @@ dumpTableData_copy(Archive *fout, const void *dcontext) classname); destroyPQExpBuffer(q); + + /* Revert back the setting */ + if (tbinfo->relkind == RELKIND_FOREIGN_TABLE) + set_restrict_relation_kind(fout, "view, foreign-table"); + return 1; } @@ -2359,6 +2376,10 @@ dumpTableData_insert(Archive *fout, const void *dcontext) int rows_per_statement = dopt->dump_inserts; int rows_this_statement = 0; + /* Temporary allows to access to foreign tables to dump data */ + if (tbinfo->relkind == RELKIND_FOREIGN_TABLE) + set_restrict_relation_kind(fout, "view"); + /* * If we're going to emit INSERTs with column names, the most efficient * way to deal with generated columns is to exclude them entirely. For @@ -2598,6 +2619,10 @@ dumpTableData_insert(Archive *fout, const void *dcontext) destroyPQExpBuffer(insertStmt); free(attgenerated); + /* Revert back the setting */ + if (tbinfo->relkind == RELKIND_FOREIGN_TABLE) + set_restrict_relation_kind(fout, "view, foreign-table"); + return 1; } @@ -4771,6 +4796,28 @@ is_superuser(Archive *fout) return false; } +/* + * Set the given value to restrict_nonsystem_relation_kind value. Since + * restrict_nonsystem_relation_kind is introduced in minor version releases, + * the setting query is effective only where available. + */ +static void +set_restrict_relation_kind(Archive *AH, const char *value) +{ + PQExpBuffer query = createPQExpBuffer(); + PGresult *res; + + appendPQExpBuffer(query, + "SELECT set_config(name, '%s', false) " + "FROM pg_settings " + "WHERE name = 'restrict_nonsystem_relation_kind'", + value); + res = ExecuteSqlQuery(AH, query->data, PGRES_TUPLES_OK); + + PQclear(res); + destroyPQExpBuffer(query); +} + /* * getSubscriptions * get information about subscriptions diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h index 147a294950..0c36d92742 100644 --- a/src/include/tcop/tcopprot.h +++ b/src/include/tcop/tcopprot.h @@ -43,6 +43,12 @@ typedef enum extern PGDLLIMPORT bool Log_disconnections; extern PGDLLIMPORT int log_statement; +/* Flags for restrict_nonsystem_relation_kind value */ +#define RESTRICT_RELKIND_VIEW 0x01 +#define RESTRICT_RELKIND_FOREIGN_TABLE 0x02 + +extern PGDLLIMPORT int restrict_nonsystem_relation_kind; + extern List *pg_parse_query(const char *query_string); extern List *pg_rewrite_query(Query *query); extern List *pg_analyze_and_rewrite_fixedparams(RawStmt *parsetree, diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h index 153c652c93..5813dba0a2 100644 --- a/src/include/utils/guc_hooks.h +++ b/src/include/utils/guc_hooks.h @@ -121,6 +121,9 @@ extern void assign_recovery_target_xid(const char *newval, void *extra); extern bool check_role(char **newval, void **extra, GucSource source); extern void assign_role(const char *newval, void *extra); extern const char *show_role(void); +extern bool check_restrict_nonsystem_relation_kind(char **newval, void **extra, + GucSource source); +extern void assign_restrict_nonsystem_relation_kind(const char *newval, void *extra); extern bool check_search_path(char **newval, void **extra, GucSource source); extern void assign_search_path(const char *newval, void *extra); extern bool check_serial_buffers(int *newval, void **extra, GucSource source); diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out index 61825ef7d4..f3f8c7b5a2 100644 --- a/src/test/regress/expected/create_view.out +++ b/src/test/regress/expected/create_view.out @@ -2202,6 +2202,21 @@ select pg_get_viewdef('tt26v', true); FROM ( VALUES (1,2,3)) v(x, y, z); (1 row) +-- test restriction on non-system view expansion. +create table tt27v_tbl (a int); +create view tt27v as select a from tt27v_tbl; +set restrict_nonsystem_relation_kind to 'view'; +select a from tt27v where a > 0; -- Error +ERROR: access to non-system view "tt27v" is restricted +insert into tt27v values (1); -- Error +ERROR: access to non-system view "tt27v" is restricted +select viewname from pg_views where viewname = 'tt27v'; -- Ok to access a system view. + viewname +---------- + tt27v +(1 row) + +reset restrict_nonsystem_relation_kind; -- clean up all the random objects we made above DROP SCHEMA temp_view_test CASCADE; NOTICE: drop cascades to 27 other objects @@ -2233,7 +2248,7 @@ drop cascades to view aliased_view_2 drop cascades to view aliased_view_3 drop cascades to view aliased_view_4 DROP SCHEMA testviewschm2 CASCADE; -NOTICE: drop cascades to 77 other objects +NOTICE: drop cascades to 79 other objects DETAIL: drop cascades to table t1 drop cascades to view temporal1 drop cascades to view temporal2 @@ -2311,3 +2326,5 @@ drop cascades to view tt23v drop cascades to view tt24v drop cascades to view tt25v drop cascades to view tt26v +drop cascades to table tt27v_tbl +drop cascades to view tt27v diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql index 8838a40f7a..3a78be1b0c 100644 --- a/src/test/regress/sql/create_view.sql +++ b/src/test/regress/sql/create_view.sql @@ -813,6 +813,15 @@ select x + y + z as c1, from (values(1,2,3)) v(x,y,z); select pg_get_viewdef('tt26v', true); +-- test restriction on non-system view expansion. +create table tt27v_tbl (a int); +create view tt27v as select a from tt27v_tbl; +set restrict_nonsystem_relation_kind to 'view'; +select a from tt27v where a > 0; -- Error +insert into tt27v values (1); -- Error +select viewname from pg_views where viewname = 'tt27v'; -- Ok to access a system view. +reset restrict_nonsystem_relation_kind; + -- clean up all the random objects we made above DROP SCHEMA temp_view_test CASCADE; DROP SCHEMA testviewschm2 CASCADE;