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 4dc54eaf0e4922450af58b52c0e19e6f8d95be38..e512f71931940e406a8b80ab985d428a39d8e7a3 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -4622,9 +4622,13 @@ 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);
                            }
@@ -4688,12 +4692,17 @@ 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 513e4183570e2ff3678a9abb7efda5d939a74ad3..22a43260ea8f58d664ec227dec772d01410d32c7 100644 (file)
--- a/src/test/regress/expected/rowsecurity.out
+++ b/src/test/regress/expected/rowsecurity.out
@@ -3490,6 +3490,27 @@ 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;
 --
 -- Clean up objects
 --

diff --git a/src/test/regress/sql/rowsecurity.sql b/src/test/regress/sql/rowsecurity.sql
index 86424d9dff2b83777b9fb82c0dff25203a2b7f84..a23b3cb05479db2aa8113f34bff98135305436fc 100644 (file)
--- a/src/test/regress/sql/rowsecurity.sql
+++ b/src/test/regress/sql/rowsecurity.sql
@@ -1601,6 +1601,26 @@ 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;
+
 --
 -- Clean up objects
 --