Fix cascading privilege revoke to notice when privileges are still held.

If we revoke a grant option from some role X, but X still holds the option
via another grant, we should not recursively revoke the privilege from
role(s) Y that X had granted it to.  This was supposedly fixed as one
aspect of commit 4b2dafcc0b, but I must not
have tested it, because in fact that code never worked: it forgot to shift
the grant-option bits back over when masking the bits being revoked.

Per bug #6728 from Daniel German.  Back-patch to all active branches,
since this has been wrong since 8.0.

src/backend/utils/adt/acl.c

@@ -1030,11 +1030,11 @@ recursive_revoke(Acl *acl,
 	if (grantee == ownerId)
 		return acl;
 
-	/* The grantee might still have the privileges via another grantor */
+	/* The grantee might still have some grant options via another grantor */
 	still_has = aclmask(acl, grantee, ownerId,
 						ACL_GRANT_OPTION_FOR(revoke_privs),
 						ACLMASK_ALL);
-	revoke_privs &= ~still_has;
+	revoke_privs &= ~ACL_OPTION_TO_PRIVS(still_has);
 	if (revoke_privs == ACL_NO_RIGHTS)
 		return acl;
 

src/test/regress/expected/privileges.out

@@ -815,6 +815,56 @@ SELECT has_table_privilege('regressuser1', 'atest4', 'SELECT WITH GRANT OPTION')
  t
 (1 row)
 
+-- test that dependent privileges are revoked (or not) properly
+\c -
+set session role regressuser1;
+create table dep_priv_test (a int);
+grant select on dep_priv_test to regressuser2 with grant option;
+grant select on dep_priv_test to regressuser3 with grant option;
+set session role regressuser2;
+grant select on dep_priv_test to regressuser4 with grant option;
+set session role regressuser3;
+grant select on dep_priv_test to regressuser4 with grant option;
+set session role regressuser4;
+grant select on dep_priv_test to regressuser5;
+\dp dep_priv_test
+                                       Access privileges
+ Schema |     Name      | Type  |         Access privileges         | Column access privileges 
+--------+---------------+-------+-----------------------------------+--------------------------
+ public | dep_priv_test | table | regressuser1=arwdDxt/regressuser1 | 
+                                : regressuser2=r*/regressuser1        
+                                : regressuser3=r*/regressuser1        
+                                : regressuser4=r*/regressuser2        
+                                : regressuser4=r*/regressuser3        
+                                : regressuser5=r/regressuser4         
+(1 row)
+
+set session role regressuser2;
+revoke select on dep_priv_test from regressuser4 cascade;
+\dp dep_priv_test
+                                       Access privileges
+ Schema |     Name      | Type  |         Access privileges         | Column access privileges 
+--------+---------------+-------+-----------------------------------+--------------------------
+ public | dep_priv_test | table | regressuser1=arwdDxt/regressuser1 | 
+                                : regressuser2=r*/regressuser1        
+                                : regressuser3=r*/regressuser1        
+                                : regressuser4=r*/regressuser3        
+                                : regressuser5=r/regressuser4         
+(1 row)
+
+set session role regressuser3;
+revoke select on dep_priv_test from regressuser4 cascade;
+\dp dep_priv_test
+                                       Access privileges
+ Schema |     Name      | Type  |         Access privileges         | Column access privileges 
+--------+---------------+-------+-----------------------------------+--------------------------
+ public | dep_priv_test | table | regressuser1=arwdDxt/regressuser1 | 
+                                : regressuser2=r*/regressuser1        
+                                : regressuser3=r*/regressuser1        
+(1 row)
+
+set session role regressuser1;
+drop table dep_priv_test;
 -- clean up
 \c
 DROP FUNCTION testfunc2(int);

src/test/regress/sql/privileges.sql

@@ -469,6 +469,30 @@ SELECT has_table_privilege('regressuser3', 'atest4', 'SELECT'); -- false
 SELECT has_table_privilege('regressuser1', 'atest4', 'SELECT WITH GRANT OPTION'); -- true
 
 
+-- test that dependent privileges are revoked (or not) properly
+\c -
+
+set session role regressuser1;
+create table dep_priv_test (a int);
+grant select on dep_priv_test to regressuser2 with grant option;
+grant select on dep_priv_test to regressuser3 with grant option;
+set session role regressuser2;
+grant select on dep_priv_test to regressuser4 with grant option;
+set session role regressuser3;
+grant select on dep_priv_test to regressuser4 with grant option;
+set session role regressuser4;
+grant select on dep_priv_test to regressuser5;
+\dp dep_priv_test
+set session role regressuser2;
+revoke select on dep_priv_test from regressuser4 cascade;
+\dp dep_priv_test
+set session role regressuser3;
+revoke select on dep_priv_test from regressuser4 cascade;
+\dp dep_priv_test
+set session role regressuser1;
+drop table dep_priv_test;
+
+
 -- clean up
 
 \c