Fix security checks for selectivity estimation functions with RLS.

In commit e2d4ef8de8, security checks were added to prevent
user-supplied operators from running over data from pg_statistic
unless the user has table or column privileges on the table, or the
operator is leakproof. For a table with RLS, however, checking for
table or column privileges is insufficient, since that does not
guarantee that the user has permission to view all of the column's
data.

Fix this by also checking for securityQuals on the RTE, and insisting
that the operator be leakproof if there are any. Thus the
leakproofness check will only be skipped if there are no securityQuals
and the user has table or column privileges on the table -- i.e., only
if we know that the user has access to all the data in the column.

Back-patch to 9.5 where RLS was added.

Dean Rasheed, reviewed by Jonathan Katz and Stephen Frost.

Security: CVE-2019-10130

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 19e76e00e0f2d412c00b44e4d23e514bfb776819..1b16ebc27b279eca2788adf46d4cc1cc045d3552 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -4568,9 +4568,13 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                                                                 * For simplicity, we insist on the whole
                                                                 * table being selectable, rather than trying
                                                                 * to identify which column(s) the index
-                                                                * depends on.
+                                                                * depends on.  Also require all rows to be
+                                                                * selectable --- there must be no
+                                                                * securityQuals from security barrier views
+                                                                * or RLS policies.
                                                                 */
                                                                vardata->acl_ok =
+                                                                       rte->securityQuals == NIL &&
                                                                        (pg_class_aclcheck(rte->relid, GetUserId(),
                                                                                                 ACL_SELECT) == ACLCHECK_OK);
                                                        }
@@ -4634,12 +4638,17 @@ examine_simple_variable(PlannerInfo *root, Var *var,
 
                if (HeapTupleIsValid(vardata->statsTuple))
                {
-                       /* check if user has permission to read this column */
+                       /*
+                        * Check if user has permission to read this column.  We require
+                        * all rows to be accessible, so there must be no securityQuals
+                        * from security barrier views or RLS policies.
+                        */
                        vardata->acl_ok =
-                               (pg_class_aclcheck(rte->relid, GetUserId(),
-                                                                  ACL_SELECT) == ACLCHECK_OK) ||
-                               (pg_attribute_aclcheck(rte->relid, var->varattno, GetUserId(),
-                                                                          ACL_SELECT) == ACLCHECK_OK);
+                               rte->securityQuals == NIL &&
+                               ((pg_class_aclcheck(rte->relid, GetUserId(),
+                                                                       ACL_SELECT) == ACLCHECK_OK) ||
+                                (pg_attribute_aclcheck(rte->relid, var->varattno, GetUserId(),
+                                                                               ACL_SELECT) == ACLCHECK_OK));
                }
                else
                {

diff --git a/src/test/regress/expected/rowsecurity.out b/src/test/regress/expected/rowsecurity.out
index f3f7afaa53f84361d3442d09420425592c6baebf..9b86c0e49eec79f6dbbda779384be8e4417d3f95 100644 (file)
--- a/src/test/regress/expected/rowsecurity.out
+++ b/src/test/regress/expected/rowsecurity.out
@@ -3492,6 +3492,27 @@ RESET SESSION AUTHORIZATION;
 DROP VIEW rls_view;
 DROP TABLE rls_tbl;
 DROP TABLE ref_tbl;
+-- Leaky operator test
+CREATE TABLE rls_tbl (a int);
+INSERT INTO rls_tbl SELECT x/10 FROM generate_series(1, 100) x;
+ANALYZE rls_tbl;
+ALTER TABLE rls_tbl ENABLE ROW LEVEL SECURITY;
+GRANT SELECT ON rls_tbl TO regress_rls_alice;
+SET SESSION AUTHORIZATION regress_rls_alice;
+CREATE FUNCTION op_leak(int, int) RETURNS bool
+    AS 'BEGIN RAISE NOTICE ''op_leak => %, %'', $1, $2; RETURN $1 < $2; END'
+    LANGUAGE plpgsql;
+CREATE OPERATOR <<< (procedure = op_leak, leftarg = int, rightarg = int,
+                     restrict = scalarltsel);
+SELECT * FROM rls_tbl WHERE a <<< 1000;
+ a 
+---
+(0 rows)
+
+DROP OPERATOR <<< (int, int);
+DROP FUNCTION op_leak(int, int);
+RESET SESSION AUTHORIZATION;
+DROP TABLE rls_tbl;
 DROP USER regress_rls_alice;
 DROP USER regress_rls_bob;
 --

diff --git a/src/test/regress/sql/rowsecurity.sql b/src/test/regress/sql/rowsecurity.sql
index fb12d02ba922252e32e2b7e7d6cae44dc08a7834..303a893a2c6871e623eb592746e609bf3ee743f3 100644 (file)
--- a/src/test/regress/sql/rowsecurity.sql
+++ b/src/test/regress/sql/rowsecurity.sql
@@ -1603,6 +1603,27 @@ RESET SESSION AUTHORIZATION;
 DROP VIEW rls_view;
 DROP TABLE rls_tbl;
 DROP TABLE ref_tbl;
+
+-- Leaky operator test
+CREATE TABLE rls_tbl (a int);
+INSERT INTO rls_tbl SELECT x/10 FROM generate_series(1, 100) x;
+ANALYZE rls_tbl;
+
+ALTER TABLE rls_tbl ENABLE ROW LEVEL SECURITY;
+GRANT SELECT ON rls_tbl TO regress_rls_alice;
+
+SET SESSION AUTHORIZATION regress_rls_alice;
+CREATE FUNCTION op_leak(int, int) RETURNS bool
+    AS 'BEGIN RAISE NOTICE ''op_leak => %, %'', $1, $2; RETURN $1 < $2; END'
+    LANGUAGE plpgsql;
+CREATE OPERATOR <<< (procedure = op_leak, leftarg = int, rightarg = int,
+                     restrict = scalarltsel);
+SELECT * FROM rls_tbl WHERE a <<< 1000;
+DROP OPERATOR <<< (int, int);
+DROP FUNCTION op_leak(int, int);
+RESET SESSION AUTHORIZATION;
+DROP TABLE rls_tbl;
+
 DROP USER regress_rls_alice;
 DROP USER regress_rls_bob;