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Perform RLS WITH CHECK before constraints, etc 

The RLS capability is built on top of the WITH CHECK OPTION
system which was added for auto-updatable views, however, unlike
WCOs on views (which are mandated by the SQL spec to not fire until
after all other constraints and checks are done), it makes much more
sense for RLS checks to happen earlier than constraint and uniqueness
checks.

This patch reworks the structure which holds the WCOs a bit to be
explicitly either VIEW or RLS checks and the RLS-related checks are
done prior to the constraint and uniqueness checks.  This also allows
better error reporting as we are now reporting when a violation is due
to a WITH CHECK OPTION and when it's due to an RLS policy violation,
which was independently noted by Craig Ringer as being confusing.

The documentation is also updated to include a paragraph about when RLS
WITH CHECK handling is performed, as there have been a number of
questions regarding that and the documentation was previously silent on
the matter.

Author: Dean Rasheed, with some kabitzing and comment changes by me.
This commit is contained in:
Stephen Frost 2015-04-24 20:34:26 -04:00
parent c8aa893862
commit e89bd02f58
15 changed files with 174 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
doc/src/sgml/ref/create_policy.sgml
View File

@ -60,6 +60,14 @@ CREATE POLICY <replaceable class="parameter">name</replaceable> ON <replaceable
expressions, as they are assumed to be trustworthy.
</para>
<para>
For INSERT and UPDATE queries, WITH CHECK expressions are enforced after
BEFORE triggers are fired, and before any data modifications are made.
Thus a BEFORE ROW trigger may modify the data to be inserted, affecting
the result of the security policy check. WITH CHECK expressions are
enforced before any other constraints.
</para>
<para>
Policy names are per-table, therefore one policy name can be used for many
different tables and have a definition for each table which is appropriate to

62
src/backend/executor/execMain.c
View File

@ -1673,9 +1673,15 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
/*
* ExecWithCheckOptions -- check that tuple satisfies any WITH CHECK OPTIONs
* of the specified kind.
*
* Note that this needs to be called multiple times to ensure that all kinds of
* WITH CHECK OPTIONs are handled (both those from views which have the WITH
* CHECK OPTION set and from row level security policies). See ExecInsert()
* and ExecUpdate().
*/
void
ExecWithCheckOptions(ResultRelInfo *resultRelInfo,
ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo,
TupleTableSlot *slot, EState *estate)
{
Relation rel = resultRelInfo->ri_RelationDesc;
@ -1700,6 +1706,13 @@ ExecWithCheckOptions(ResultRelInfo *resultRelInfo,
WithCheckOption *wco = (WithCheckOption *) lfirst(l1);
ExprState *wcoExpr = (ExprState *) lfirst(l2);
/*
* Skip any WCOs which are not the kind we are looking for at this
* time.
*/
if (wco->kind != kind)
continue;
/*
* WITH CHECK OPTION checks are intended to ensure that the new tuple
* is visible (in the case of a view) or that it passes the
@ -1714,19 +1727,42 @@ ExecWithCheckOptions(ResultRelInfo *resultRelInfo,
char *val_desc;
Bitmapset *modifiedCols;
modifiedCols = GetModifiedColumns(resultRelInfo, estate);
val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
slot,
tupdesc,
modifiedCols,
64);
switch (wco->kind)
{
/*
* For WITH CHECK OPTIONs coming from views, we might be able to
* provide the details on the row, depending on the permissions
* on the relation (that is, if the user could view it directly
* anyway). For RLS violations, we don't include the data since
* we don't know if the user should be able to view the tuple as
* as that depends on the USING policy.
*/
case WCO_VIEW_CHECK:
modifiedCols = GetModifiedColumns(resultRelInfo, estate);
val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
slot,
tupdesc,
modifiedCols,
64);
ereport(ERROR,
(errcode(ERRCODE_WITH_CHECK_OPTION_VIOLATION),
errmsg("new row violates WITH CHECK OPTION for \"%s\"",
wco->viewname),
val_desc ? errdetail("Failing row contains %s.", val_desc) :
0));
ereport(ERROR,
(errcode(ERRCODE_WITH_CHECK_OPTION_VIOLATION),
errmsg("new row violates WITH CHECK OPTION for \"%s\"",
wco->relname),
val_desc ? errdetail("Failing row contains %s.",
val_desc) : 0));
break;
case WCO_RLS_INSERT_CHECK:
case WCO_RLS_UPDATE_CHECK:
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("new row violates row level security policy for \"%s\"",
wco->relname)));
break;
default:
elog(ERROR, "unrecognized WCO kind: %u", wco->kind);
break;
}
}
}
}

58
src/backend/executor/nodeModifyTable.c
View File

@ -252,6 +252,16 @@ ExecInsert(TupleTableSlot *slot,
*/
tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
/*
* Check any RLS INSERT WITH CHECK policies
*
* ExecWithCheckOptions() will skip any WCOs which are not of
* the kind we are looking for at this point.
*/
if (resultRelInfo->ri_WithCheckOptions != NIL)
ExecWithCheckOptions(WCO_RLS_INSERT_CHECK,
resultRelInfo, slot, estate);
/*
* Check the constraints of the tuple
*/
@ -287,9 +297,21 @@ ExecInsert(TupleTableSlot *slot,
list_free(recheckIndexes);
/* Check any WITH CHECK OPTION constraints */
/*
* Check any WITH CHECK OPTION constraints from parent views. We
* are required to do this after testing all constraints and
* uniqueness violations per the SQL spec, so we do it after actually
* inserting the record into the heap and all indexes.
*
* ExecWithCheckOptions will elog(ERROR) if a violation is found, so
* the tuple will never be seen, if it violates the the WITH CHECK
* OPTION.
*
* ExecWithCheckOptions() will skip any WCOs which are not of
* the kind we are looking for at this point.
*/
if (resultRelInfo->ri_WithCheckOptions != NIL)
ExecWithCheckOptions(resultRelInfo, slot, estate);
ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
/* Process RETURNING if present */
if (resultRelInfo->ri_projectReturning)
@ -653,15 +675,25 @@ ExecUpdate(ItemPointer tupleid,
tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
/*
* Check the constraints of the tuple
* Check any RLS UPDATE WITH CHECK policies
*
* If we generate a new candidate tuple after EvalPlanQual testing, we
* must loop back here and recheck constraints. (We don't need to
* redo triggers, however. If there are any BEFORE triggers then
* trigger.c will have done heap_lock_tuple to lock the correct tuple,
* so there's no need to do them again.)
* must loop back here and recheck any RLS policies and constraints.
* (We don't need to redo triggers, however. If there are any BEFORE
* triggers then trigger.c will have done heap_lock_tuple to lock the
* correct tuple, so there's no need to do them again.)
*
* ExecWithCheckOptions() will skip any WCOs which are not of
* the kind we are looking for at this point.
*/
lreplace:;
if (resultRelInfo->ri_WithCheckOptions != NIL)
ExecWithCheckOptions(WCO_RLS_UPDATE_CHECK,
resultRelInfo, slot, estate);
/*
* Check the constraints of the tuple
*/
if (resultRelationDesc->rd_att->constr)
ExecConstraints(resultRelInfo, slot, estate);
@ -780,9 +812,17 @@ lreplace:;
list_free(recheckIndexes);
/* Check any WITH CHECK OPTION constraints */
/*
* Check any WITH CHECK OPTION constraints from parent views. We
* are required to do this after testing all constraints and
* uniqueness violations per the SQL spec, so we do it after actually
* updating the record in the heap and all indexes.
*
* ExecWithCheckOptions() will skip any WCOs which are not of
* the kind we are looking for at this point.
*/
if (resultRelInfo->ri_WithCheckOptions != NIL)
ExecWithCheckOptions(resultRelInfo, slot, estate);
ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
/* Process RETURNING if present */
if (resultRelInfo->ri_projectReturning)

3
src/backend/nodes/copyfuncs.c
View File

@ -2064,7 +2064,8 @@ _copyWithCheckOption(const WithCheckOption *from)
{
WithCheckOption *newnode = makeNode(WithCheckOption);
COPY_STRING_FIELD(viewname);
COPY_SCALAR_FIELD(kind);
COPY_STRING_FIELD(relname);
COPY_NODE_FIELD(qual);
COPY_SCALAR_FIELD(cascaded);

3
src/backend/nodes/equalfuncs.c
View File

@ -2363,7 +2363,8 @@ _equalRangeTblFunction(const RangeTblFunction *a, const RangeTblFunction *b)
static bool
_equalWithCheckOption(const WithCheckOption *a, const WithCheckOption *b)
{
COMPARE_STRING_FIELD(viewname);
COMPARE_SCALAR_FIELD(kind);
COMPARE_STRING_FIELD(relname);
COMPARE_NODE_FIELD(qual);
COMPARE_SCALAR_FIELD(cascaded);

3
src/backend/nodes/outfuncs.c
View File

@ -2332,7 +2332,8 @@ _outWithCheckOption(StringInfo str, const WithCheckOption *node)
{
WRITE_NODE_TYPE("WITHCHECKOPTION");
WRITE_STRING_FIELD(viewname);
WRITE_ENUM_FIELD(kind, WCOKind);
WRITE_STRING_FIELD(relname);
WRITE_NODE_FIELD(qual);
WRITE_BOOL_FIELD(cascaded);
}

3
src/backend/nodes/readfuncs.c
View File

@ -266,7 +266,8 @@ _readWithCheckOption(void)
{
READ_LOCALS(WithCheckOption);
READ_STRING_FIELD(viewname);
READ_ENUM_FIELD(kind, WCOKind);
READ_STRING_FIELD(relname);
READ_NODE_FIELD(qual);
READ_BOOL_FIELD(cascaded);

3
src/backend/rewrite/rewriteHandler.c
View File

@ -2947,7 +2947,8 @@ rewriteTargetView(Query *parsetree, Relation view)
WithCheckOption *wco;
wco = makeNode(WithCheckOption);
wco->viewname = pstrdup(RelationGetRelationName(view));
wco->kind = WCO_VIEW_CHECK;
wco->relname = pstrdup(RelationGetRelationName(view));
wco->qual = NULL;
wco->cascaded = cascaded;

26
src/backend/rewrite/rowsecurity.c
View File

@ -259,7 +259,9 @@ get_row_security_policies(Query* root, RangeTblEntry* rte, int rt_index,
WithCheckOption *wco;
wco = (WithCheckOption *) makeNode(WithCheckOption);
wco->viewname = pstrdup(RelationGetRelationName(rel));
wco->kind = root->commandType == CMD_INSERT ? WCO_RLS_INSERT_CHECK :
WCO_RLS_UPDATE_CHECK;
wco->relname = pstrdup(RelationGetRelationName(rel));
wco->qual = (Node *) hook_with_check_expr_restrictive;
wco->cascaded = false;
*withCheckOptions = lappend(*withCheckOptions, wco);
@ -274,7 +276,9 @@ get_row_security_policies(Query* root, RangeTblEntry* rte, int rt_index,
WithCheckOption *wco;
wco = (WithCheckOption *) makeNode(WithCheckOption);
wco->viewname = pstrdup(RelationGetRelationName(rel));
wco->kind = root->commandType == CMD_INSERT ? WCO_RLS_INSERT_CHECK :
WCO_RLS_UPDATE_CHECK;
wco->relname = pstrdup(RelationGetRelationName(rel));
wco->qual = (Node *) rowsec_with_check_expr;
wco->cascaded = false;
*withCheckOptions = lappend(*withCheckOptions, wco);
@ -285,7 +289,9 @@ get_row_security_policies(Query* root, RangeTblEntry* rte, int rt_index,
WithCheckOption *wco;
wco = (WithCheckOption *) makeNode(WithCheckOption);
wco->viewname = pstrdup(RelationGetRelationName(rel));
wco->kind = root->commandType == CMD_INSERT ? WCO_RLS_INSERT_CHECK :
WCO_RLS_UPDATE_CHECK;
wco->relname = pstrdup(RelationGetRelationName(rel));
wco->qual = (Node *) hook_with_check_expr_permissive;
wco->cascaded = false;
*withCheckOptions = lappend(*withCheckOptions, wco);
@ -297,13 +303,18 @@ get_row_security_policies(Query* root, RangeTblEntry* rte, int rt_index,
List *combined_quals = NIL;
Expr *combined_qual_eval;
combined_quals = lcons(copyObject(rowsec_with_check_expr), combined_quals);
combined_quals = lcons(copyObject(hook_with_check_expr_permissive), combined_quals);
combined_quals = lcons(copyObject(rowsec_with_check_expr),
combined_quals);
combined_quals = lcons(copyObject(hook_with_check_expr_permissive),
combined_quals);
combined_qual_eval = makeBoolExpr(OR_EXPR, combined_quals, -1);
wco = (WithCheckOption *) makeNode(WithCheckOption);
wco->viewname = pstrdup(RelationGetRelationName(rel));
wco->kind = root->commandType == CMD_INSERT ? WCO_RLS_INSERT_CHECK :
WCO_RLS_UPDATE_CHECK;
wco->relname = pstrdup(RelationGetRelationName(rel));
wco->qual = (Node *) combined_qual_eval;
wco->cascaded = false;
*withCheckOptions = lappend(*withCheckOptions, wco);
@ -332,7 +343,8 @@ get_row_security_policies(Query* root, RangeTblEntry* rte, int rt_index,
Expr *combined_qual_eval;
combined_quals = lcons(copyObject(rowsec_expr), combined_quals);
combined_quals = lcons(copyObject(hook_expr_permissive), combined_quals);
combined_quals = lcons(copyObject(hook_expr_permissive),
combined_quals);
combined_qual_eval = makeBoolExpr(OR_EXPR, combined_quals, -1);

2
src/include/executor/executor.h
View File

@ -193,7 +193,7 @@ extern ResultRelInfo *ExecGetTriggerResultRel(EState *estate, Oid relid);
extern bool ExecContextForcesOids(PlanState *planstate, bool *hasoids);
extern void ExecConstraints(ResultRelInfo *resultRelInfo,
TupleTableSlot *slot, EState *estate);
extern void ExecWithCheckOptions(ResultRelInfo *resultRelInfo,
extern void ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo,
TupleTableSlot *slot, EState *estate);
extern ExecRowMark *ExecFindRowMark(EState *estate, Index rti);
extern ExecAuxRowMark *ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist);

2
src/include/nodes/execnodes.h
View File

@ -303,7 +303,7 @@ typedef struct JunkFilter
* TrigInstrument optional runtime measurements for triggers
* FdwRoutine FDW callback functions, if foreign table
* FdwState available to save private state of FDW
* WithCheckOptions list of WithCheckOption's for views
* WithCheckOptions list of WithCheckOption's to be checked
* WithCheckOptionExprs list of WithCheckOption expr states
* ConstraintExprs array of constraint-checking expr states
* junkFilter for removing junk attributes from tuples

15
src/include/nodes/parsenodes.h
View File

@ -872,14 +872,23 @@ typedef struct RangeTblFunction
/*
* WithCheckOption -
* representation of WITH CHECK OPTION checks to be applied to new tuples
* when inserting/updating an auto-updatable view.
* when inserting/updating an auto-updatable view, or RLS WITH CHECK
* policies to be applied when inserting/updating a relation with RLS.
*/
typedef enum WCOKind
{
WCO_VIEW_CHECK, /* WCO on an auto-updatable view */
WCO_RLS_INSERT_CHECK, /* RLS INSERT WITH CHECK policy */
WCO_RLS_UPDATE_CHECK /* RLS UPDATE WITH CHECK policy */
} WCOKind;
typedef struct WithCheckOption
{
NodeTag type;
char *viewname; /* name of view that specified the WCO */
WCOKind kind; /* kind of WCO */
char *relname; /* name of relation that specified the WCO */
Node *qual; /* constraint qual to check */
bool cascaded; /* true = WITH CASCADED CHECK OPTION */
bool cascaded; /* true for a cascaded WCO on a view */
} WithCheckOption;
/*

24
src/test/modules/test_rls_hooks/expected/test_rls_hooks.out
View File

@ -57,7 +57,7 @@ SELECT * FROM rls_test_permissive;
INSERT INTO rls_test_permissive VALUES ('r1','s1',10);
-- failure
INSERT INTO rls_test_permissive VALUES ('r4','s4',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_permissive"
ERROR: new row violates row level security policy for "rls_test_permissive"
SET ROLE s1;
-- With only the hook's policies, restrictive
-- hook's policy is current_user = supervisor
@ -78,7 +78,7 @@ SELECT * FROM rls_test_restrictive;
INSERT INTO rls_test_restrictive VALUES ('r1','s1',10);
-- failure
INSERT INTO rls_test_restrictive VALUES ('r4','s4',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_restrictive"
ERROR: new row violates row level security policy for "rls_test_restrictive"
SET ROLE s1;
-- With only the hook's policies, both
-- permissive hook's policy is current_user = username
@ -100,13 +100,13 @@ SELECT * FROM rls_test_both;
-- failure
INSERT INTO rls_test_both VALUES ('r1','s1',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
-- failure
INSERT INTO rls_test_both VALUES ('r4','s1',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
-- failure
INSERT INTO rls_test_both VALUES ('r4','s4',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
RESET ROLE;
-- Create "internal" policies, to check that the policies from
-- the hooks are combined correctly.
@ -136,7 +136,7 @@ INSERT INTO rls_test_permissive VALUES ('r1','s1',7);
INSERT INTO rls_test_permissive VALUES ('r3','s3',10);
-- failure
INSERT INTO rls_test_permissive VALUES ('r4','s4',7);
ERROR: new row violates WITH CHECK OPTION for "rls_test_permissive"
ERROR: new row violates row level security policy for "rls_test_permissive"
SET ROLE s1;
-- With both internal and hook policies, restrictive
EXPLAIN (costs off) SELECT * FROM rls_test_restrictive;
@ -158,13 +158,13 @@ SELECT * FROM rls_test_restrictive;
INSERT INTO rls_test_restrictive VALUES ('r1','s1',8);
-- failure
INSERT INTO rls_test_restrictive VALUES ('r3','s3',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_restrictive"
ERROR: new row violates row level security policy for "rls_test_restrictive"
-- failure
INSERT INTO rls_test_restrictive VALUES ('r1','s1',7);
ERROR: new row violates WITH CHECK OPTION for "rls_test_restrictive"
ERROR: new row violates row level security policy for "rls_test_restrictive"
-- failure
INSERT INTO rls_test_restrictive VALUES ('r4','s4',7);
ERROR: new row violates WITH CHECK OPTION for "rls_test_restrictive"
ERROR: new row violates row level security policy for "rls_test_restrictive"
-- With both internal and hook policies, both permissive
-- and restrictive hook policies
EXPLAIN (costs off) SELECT * FROM rls_test_both;
@ -185,13 +185,13 @@ SELECT * FROM rls_test_both;
INSERT INTO rls_test_both VALUES ('r1','s1',8);
-- failure
INSERT INTO rls_test_both VALUES ('r3','s3',10);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
-- failure
INSERT INTO rls_test_both VALUES ('r1','s1',7);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
-- failure
INSERT INTO rls_test_both VALUES ('r4','s4',7);
ERROR: new row violates WITH CHECK OPTION for "rls_test_both"
ERROR: new row violates row level security policy for "rls_test_both"
RESET ROLE;
DROP TABLE rls_test_restrictive;
DROP TABLE rls_test_permissive;

13
src/test/regress/expected/rowsecurity.out
View File

@ -300,6 +300,11 @@ SELECT * FROM document WHERE did = 8; -- and confirm we can't see it
-----+-----+--------+---------+--------
(0 rows)
-- RLS policies are checked before constraints
INSERT INTO document VALUES (8, 44, 1, 'rls_regress_user2', 'my third manga'); -- Should fail with RLS check violation, not duplicate key violation
ERROR: new row violates row level security policy for "document"
UPDATE document SET did = 8, dauthor = 'rls_regress_user2' WHERE did = 5; -- Should fail with RLS check violation, not duplicate key violation
ERROR: new row violates row level security policy for "document"
-- database superuser does bypass RLS policy when enabled
RESET SESSION AUTHORIZATION;
SET row_security TO ON;
@ -1426,9 +1431,9 @@ NOTICE: f_leak => d3d9446802a44259755d38e6d163e820
(5 rows)
INSERT INTO bv1 VALUES (-1, 'xxx'); -- should fail view WCO
ERROR: new row violates WITH CHECK OPTION for "b1"
ERROR: new row violates row level security policy for "b1"
INSERT INTO bv1 VALUES (11, 'xxx'); -- should fail RLS check
ERROR: new row violates WITH CHECK OPTION for "b1"
ERROR: new row violates row level security policy for "b1"
INSERT INTO bv1 VALUES (12, 'xxx'); -- ok
EXPLAIN (COSTS OFF) UPDATE bv1 SET b = 'yyy' WHERE a = 4 AND f_leak(b);
QUERY PLAN
@ -1988,7 +1993,7 @@ EXPLAIN (COSTS OFF) WITH cte1 AS (SELECT * FROM t1 WHERE f_leak(b)) SELECT * FRO
(6 rows)
WITH cte1 AS (UPDATE t1 SET a = a + 1 RETURNING *) SELECT * FROM cte1; --fail
ERROR: new row violates WITH CHECK OPTION for "t1"
ERROR: new row violates row level security policy for "t1"
WITH cte1 AS (UPDATE t1 SET a = a RETURNING *) SELECT * FROM cte1; --ok
a | b
----+----------------------------------
@ -2006,7 +2011,7 @@ WITH cte1 AS (UPDATE t1 SET a = a RETURNING *) SELECT * FROM cte1; --ok
(11 rows)
WITH cte1 AS (INSERT INTO t1 VALUES (21, 'Fail') RETURNING *) SELECT * FROM cte1; --fail
ERROR: new row violates WITH CHECK OPTION for "t1"
ERROR: new row violates row level security policy for "t1"
WITH cte1 AS (INSERT INTO t1 VALUES (20, 'Success') RETURNING *) SELECT * FROM cte1; --ok
a | b
----+---------

4
src/test/regress/sql/rowsecurity.sql
View File

@ -146,6 +146,10 @@ SET SESSION AUTHORIZATION rls_regress_user1;
INSERT INTO document VALUES (8, 44, 1, 'rls_regress_user1', 'my third manga'); -- Must fail with unique violation, revealing presence of did we can't see
SELECT * FROM document WHERE did = 8; -- and confirm we can't see it
-- RLS policies are checked before constraints
INSERT INTO document VALUES (8, 44, 1, 'rls_regress_user2', 'my third manga'); -- Should fail with RLS check violation, not duplicate key violation
UPDATE document SET did = 8, dauthor = 'rls_regress_user2' WHERE did = 5; -- Should fail with RLS check violation, not duplicate key violation
-- database superuser does bypass RLS policy when enabled
RESET SESSION AUTHORIZATION;
SET row_security TO ON;