/* -------------------------------------------------------------------------
*
* contrib/sepgsql/dml.c
*
* Routines to handle DML permission checks
*
* Copyright (c) 2010-2022, PostgreSQL Global Development Group
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/tupdesc.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/pg_attribute.h"
#include "catalog/pg_class.h"
#include "catalog/pg_inherits.h"
#include "commands/seclabel.h"
#include "commands/tablecmds.h"
#include "executor/executor.h"
#include "nodes/bitmapset.h"
#include "sepgsql.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
/*
* fixup_whole_row_references
*
* When user references a whole-row Var, it is equivalent to referencing
* all the user columns (not system columns). So, we need to fix up the
* given bitmapset, if it contains a whole-row reference.
*/
static Bitmapset *
fixup_whole_row_references(Oid relOid, Bitmapset *columns)
{
Bitmapset *result;
HeapTuple tuple;
AttrNumber natts;
AttrNumber attno;
int index;
/* if no whole-row references, nothing to do */
index = InvalidAttrNumber - FirstLowInvalidHeapAttributeNumber;
if (!bms_is_member(index, columns))
return columns;
/* obtain number of attributes */
tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for relation %u", relOid);
natts = ((Form_pg_class) GETSTRUCT(tuple))->relnatts;
ReleaseSysCache(tuple);
/* remove bit 0 from column set, add in all the non-dropped columns */
result = bms_copy(columns);
result = bms_del_member(result, index);
for (attno = 1; attno <= natts; attno++)
{
tuple = SearchSysCache2(ATTNUM,
ObjectIdGetDatum(relOid),
Int16GetDatum(attno));
if (!HeapTupleIsValid(tuple))
continue; /* unexpected case, should we error? */
if (!((Form_pg_attribute) GETSTRUCT(tuple))->attisdropped)
{
index = attno - FirstLowInvalidHeapAttributeNumber;
result = bms_add_member(result, index);
}
ReleaseSysCache(tuple);
}
return result;
}
/*
* fixup_inherited_columns
*
* When user is querying on a table with children, it implicitly accesses
* child tables also. So, we also need to check security label of child
* tables and columns, but here is no guarantee attribute numbers are
* same between the parent and children.
* It returns a bitmapset which contains attribute number of the child
* table based on the given bitmapset of the parent.
*/
static Bitmapset *
fixup_inherited_columns(Oid parentId, Oid childId, Bitmapset *columns)
{
Bitmapset *result = NULL;
int index;
/*
* obviously, no need to do anything here
*/
if (parentId == childId)
return columns;
index = -1;
while ((index = bms_next_member(columns, index)) >= 0)
{
/* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
AttrNumber attno = index + FirstLowInvalidHeapAttributeNumber;
char *attname;
/*
* whole-row-reference shall be fixed-up later
*/
if (attno == InvalidAttrNumber)
{
result = bms_add_member(result, index);
continue;
}
attname = get_attname(parentId, attno, false);
attno = get_attnum(childId, attname);
if (attno == InvalidAttrNumber)
elog(ERROR, "cache lookup failed for attribute %s of relation %u",
attname, childId);
result = bms_add_member(result,
attno - FirstLowInvalidHeapAttributeNumber);
pfree(attname);
}
return result;
}
/*
* check_relation_privileges
*
* It actually checks required permissions on a certain relation
* and its columns.
*/
static bool
check_relation_privileges(Oid relOid,
Bitmapset *selected,
Bitmapset *inserted,
Bitmapset *updated,
uint32 required,
bool abort_on_violation)
{
ObjectAddress object;
char *audit_name;
Bitmapset *columns;
int index;
char relkind = get_rel_relkind(relOid);
bool result = true;
/*
* Hardwired Policies: SE-PostgreSQL enforces - clients cannot modify
* system catalogs using DMLs - clients cannot reference/modify toast
* relations using DMLs
*/
if (sepgsql_getenforce() > 0)
{
if ((required & (SEPG_DB_TABLE__UPDATE |
SEPG_DB_TABLE__INSERT |
SEPG_DB_TABLE__DELETE)) != 0 &&
IsCatalogRelationOid(relOid))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("SELinux: hardwired security policy violation")));
if (relkind == RELKIND_TOASTVALUE)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("SELinux: hardwired security policy violation")));
}
/*
* Check permissions on the relation
*/
object.classId = RelationRelationId;
object.objectId = relOid;
object.objectSubId = 0;
audit_name = getObjectIdentity(&object, false);
switch (relkind)
{
case RELKIND_RELATION:
case RELKIND_PARTITIONED_TABLE:
result = sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_TABLE,
required,
audit_name,
abort_on_violation);
break;
case RELKIND_SEQUENCE:
Assert((required & ~SEPG_DB_TABLE__SELECT) == 0);
if (required & SEPG_DB_TABLE__SELECT)
result = sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_SEQUENCE,
SEPG_DB_SEQUENCE__GET_VALUE,
audit_name,
abort_on_violation);
break;
case RELKIND_VIEW:
result = sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_VIEW,
SEPG_DB_VIEW__EXPAND,
audit_name,
abort_on_violation);
break;
default:
/* nothing to be checked */
break;
}
pfree(audit_name);
/*
* Only columns owned by relations shall be checked
*/
if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE)
return true;
/*
* Check permissions on the columns
*/
selected = fixup_whole_row_references(relOid, selected);
inserted = fixup_whole_row_references(relOid, inserted);
updated = fixup_whole_row_references(relOid, updated);
columns = bms_union(selected, bms_union(inserted, updated));
while ((index = bms_first_member(columns)) >= 0)
{
AttrNumber attnum;
uint32 column_perms = 0;
if (bms_is_member(index, selected))
column_perms |= SEPG_DB_COLUMN__SELECT;
if (bms_is_member(index, inserted))
{
if (required & SEPG_DB_TABLE__INSERT)
column_perms |= SEPG_DB_COLUMN__INSERT;
}
if (bms_is_member(index, updated))
{
if (required & SEPG_DB_TABLE__UPDATE)
column_perms |= SEPG_DB_COLUMN__UPDATE;
}
if (column_perms == 0)
continue;
/* obtain column's permission */
attnum = index + FirstLowInvalidHeapAttributeNumber;
object.classId = RelationRelationId;
object.objectId = relOid;
object.objectSubId = attnum;
audit_name = getObjectDescription(&object, false);
result = sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_COLUMN,
column_perms,
audit_name,
abort_on_violation);
pfree(audit_name);
if (!result)
return result;
}
return true;
}
/*
* sepgsql_dml_privileges
*
* Entrypoint of the DML permission checks
*/
bool
sepgsql_dml_privileges(List *rangeTabls, bool abort_on_violation)
{
ListCell *lr;
foreach(lr, rangeTabls)
{
RangeTblEntry *rte = lfirst(lr);
uint32 required = 0;
List *tableIds;
ListCell *li;
/*
* Only regular relations shall be checked
*/
if (rte->rtekind != RTE_RELATION)
continue;
/*
* Find out required permissions
*/
if (rte->requiredPerms & ACL_SELECT)
required |= SEPG_DB_TABLE__SELECT;
if (rte->requiredPerms & ACL_INSERT)
required |= SEPG_DB_TABLE__INSERT;
if (rte->requiredPerms & ACL_UPDATE)
{
if (!bms_is_empty(rte->updatedCols))
required |= SEPG_DB_TABLE__UPDATE;
else
required |= SEPG_DB_TABLE__LOCK;
}
if (rte->requiredPerms & ACL_DELETE)
required |= SEPG_DB_TABLE__DELETE;
/*
* Skip, if nothing to be checked
*/
if (required == 0)
continue;
/*
* If this RangeTblEntry is also supposed to reference inherited
* tables, we need to check security label of the child tables. So, we
* expand rte->relid into list of OIDs of inheritance hierarchy, then
* checker routine will be invoked for each relations.
*/
if (!rte->inh)
tableIds = list_make1_oid(rte->relid);
else
tableIds = find_all_inheritors(rte->relid, NoLock, NULL);
foreach(li, tableIds)
{
Oid tableOid = lfirst_oid(li);
Bitmapset *selectedCols;
Bitmapset *insertedCols;
Bitmapset *updatedCols;
/*
* child table has different attribute numbers, so we need to fix
* up them.
*/
selectedCols = fixup_inherited_columns(rte->relid, tableOid,
rte->selectedCols);
insertedCols = fixup_inherited_columns(rte->relid, tableOid,
rte->insertedCols);
updatedCols = fixup_inherited_columns(rte->relid, tableOid,
rte->updatedCols);
/*
* check permissions on individual tables
*/
if (!check_relation_privileges(tableOid,
selectedCols,
insertedCols,
updatedCols,
required, abort_on_violation))
return false;
}
list_free(tableIds);
}
return true;
}