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

1 files changed, 47 insertions, 0 deletions

diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 6576efaeeec..3dbc2c4ff17 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -291,6 +291,7 @@ static void appendReloptionsArrayAH(PQExpBuffer buffer, const char *reloptions,
 static char *get_synchronized_snapshot(Archive *fout);
 static void setupDumpWorker(Archive *AHX);
 static TableInfo *getRootTableInfo(TableInfo *tbinfo);
+static void set_restrict_relation_kind(Archive *AH, const char *value);
 static bool forcePartitionRootLoad(const TableInfo *tbinfo);
 
 
@@ -1179,6 +1180,13 @@ setup_connection(Archive *AH, const char *dumpencoding,
 	}
 
 	/*
+	 * 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");
+
+	/*
 	 * Start transaction-snapshot mode transaction to dump consistent data.
 	 */
 	ExecuteSqlStatement(AH, "BEGIN");
@@ -1900,6 +1908,10 @@ dumpTableData_copy(Archive *fout, 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");
+
 		/* Note: this syntax is only supported in 8.2 and up */
 		appendPQExpBufferStr(q, "COPY (SELECT ");
 		/* klugery to get rid of parens in column list */
@@ -2012,6 +2024,11 @@ dumpTableData_copy(Archive *fout, 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;
 }
 
@@ -2038,6 +2055,10 @@ dumpTableData_insert(Archive *fout, 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
@@ -2277,6 +2298,10 @@ dumpTableData_insert(Archive *fout, 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;
 }
 
@@ -4307,6 +4332,28 @@ is_superuser(Archive *fout)
 }
 
 /*
+ * 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
  */