Improve RLS handling in copy.c

To avoid a race condition where the relation being COPY'd could be
changed into a view or otherwise modified, keep the original lock
on the relation.  Further, fully qualify the relation when building
the query up.

Also remove the poorly thought-out Assert() and check the entire
relationOids list as, post-RLS, there can certainly be multiple
relations involved and the planner does not guarantee their ordering.

Per discussion with Noah and Andres.

Back-patch to 9.5 where RLS was introduced.

2 files changed, 99 insertions, 2 deletions

diff --git a/src/test/regress/expected/rowsecurity.out b/src/test/regress/expected/rowsecurity.out
index e7c242cd22..72361e82a5 100644
--- a/src/test/regress/expected/rowsecurity.out
+++ b/src/test/regress/expected/rowsecurity.out
@@ -2672,7 +2672,7 @@ COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --ok
 6,1679091c5a880faf6fb5e6087eb1b2dc
 8,c9f0f895fb98ab9159f51fd0297e236d
 10,d3d9446802a44259755d38e6d163e820
--- Check COPY TO as user without permissions.SET row_security TO OFF;
+-- Check COPY TO as user without permissions. SET row_security TO OFF;
 SET SESSION AUTHORIZATION rls_regress_user2;
 SET row_security TO OFF;
 COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --fail - insufficient to bypass rls
@@ -2683,6 +2683,53 @@ ERROR:  permission denied for relation copy_t
 SET row_security TO FORCE;
 COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --fail - permission denied
 ERROR:  permission denied for relation copy_t
+-- Check COPY relation TO; keep it just one row to avoid reordering issues
+RESET SESSION AUTHORIZATION;
+SET row_security TO ON;
+CREATE TABLE copy_rel_to (a integer, b text);
+CREATE POLICY p1 ON copy_rel_to USING (a % 2 = 0);
+ALTER TABLE copy_rel_to ENABLE ROW LEVEL SECURITY;
+GRANT ALL ON copy_rel_to TO rls_regress_user1, rls_regress_exempt_user;
+INSERT INTO copy_rel_to VALUES (1, md5('1'));
+-- Check COPY TO as Superuser/owner.
+RESET SESSION AUTHORIZATION;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+1,c4ca4238a0b923820dcc509a6f75849b
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+1,c4ca4238a0b923820dcc509a6f75849b
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+-- Check COPY TO as user with permissions.
+SET SESSION AUTHORIZATION rls_regress_user1;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - insufficient to bypass rls
+ERROR:  insufficient privilege to bypass row security.
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+-- Check COPY TO as user with permissions and BYPASSRLS
+SET SESSION AUTHORIZATION rls_regress_exempt_user;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+1,c4ca4238a0b923820dcc509a6f75849b
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+-- Check COPY TO as user without permissions. SET row_security TO OFF;
+SET SESSION AUTHORIZATION rls_regress_user2;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+ERROR:  permission denied for relation copy_rel_to
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+ERROR:  permission denied for relation copy_rel_to
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+ERROR:  permission denied for relation copy_rel_to
 -- Check COPY FROM as Superuser/owner.
 RESET SESSION AUTHORIZATION;
 SET row_security TO OFF;
@@ -2731,6 +2778,7 @@ COPY copy_t FROM STDIN; --fail - permission denied.
 ERROR:  permission denied for relation copy_t
 RESET SESSION AUTHORIZATION;
 DROP TABLE copy_t;
+DROP TABLE copy_rel_to CASCADE;
 -- Check WHERE CURRENT OF
 SET SESSION AUTHORIZATION rls_regress_user0;
 CREATE TABLE current_check (currentid int, payload text, rlsuser text);
diff --git a/src/test/regress/sql/rowsecurity.sql b/src/test/regress/sql/rowsecurity.sql
index e86f814314..f588fa2337 100644
--- a/src/test/regress/sql/rowsecurity.sql
+++ b/src/test/regress/sql/rowsecurity.sql
@@ -1028,7 +1028,7 @@ COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --ok
 SET row_security TO FORCE;
 COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --ok
 
--- Check COPY TO as user without permissions.SET row_security TO OFF;
+-- Check COPY TO as user without permissions. SET row_security TO OFF;
 SET SESSION AUTHORIZATION rls_regress_user2;
 SET row_security TO OFF;
 COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --fail - insufficient to bypass rls
@@ -1037,6 +1037,54 @@ COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --fail
 SET row_security TO FORCE;
 COPY (SELECT * FROM copy_t ORDER BY a ASC) TO STDOUT WITH DELIMITER ','; --fail - permission denied
 
+-- Check COPY relation TO; keep it just one row to avoid reordering issues
+RESET SESSION AUTHORIZATION;
+SET row_security TO ON;
+CREATE TABLE copy_rel_to (a integer, b text);
+CREATE POLICY p1 ON copy_rel_to USING (a % 2 = 0);
+
+ALTER TABLE copy_rel_to ENABLE ROW LEVEL SECURITY;
+
+GRANT ALL ON copy_rel_to TO rls_regress_user1, rls_regress_exempt_user;
+
+INSERT INTO copy_rel_to VALUES (1, md5('1'));
+
+-- Check COPY TO as Superuser/owner.
+RESET SESSION AUTHORIZATION;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ',';
+
+-- Check COPY TO as user with permissions.
+SET SESSION AUTHORIZATION rls_regress_user1;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - insufficient to bypass rls
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+
+-- Check COPY TO as user with permissions and BYPASSRLS
+SET SESSION AUTHORIZATION rls_regress_exempt_user;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --ok
+
+-- Check COPY TO as user without permissions. SET row_security TO OFF;
+SET SESSION AUTHORIZATION rls_regress_user2;
+SET row_security TO OFF;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+SET row_security TO ON;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+SET row_security TO FORCE;
+COPY copy_rel_to TO STDOUT WITH DELIMITER ','; --fail - permission denied
+
 -- Check COPY FROM as Superuser/owner.
 RESET SESSION AUTHORIZATION;
 SET row_security TO OFF;
@@ -1090,6 +1138,7 @@ COPY copy_t FROM STDIN; --fail - permission denied.
 
 RESET SESSION AUTHORIZATION;
 DROP TABLE copy_t;
+DROP TABLE copy_rel_to CASCADE;
 
 -- Check WHERE CURRENT OF
 SET SESSION AUTHORIZATION rls_regress_user0;