-
Tom Lane authored
an allegedly immutable index function. It was previously recognized that we had to prevent such a function from executing SET/RESET ROLE/SESSION AUTHORIZATION, or it could trivially obtain the privileges of the session user. However, since there is in general no privilege checking for changes of session-local state, it is also possible for such a function to change settings in a way that might subvert later operations in the same session. Examples include changing search_path to cause an unexpected function to be called, or replacing an existing prepared statement with another one that will execute a function of the attacker's choosing. The present patch secures VACUUM, ANALYZE, and CREATE INDEX/REINDEX against these threats, which are the same places previously deemed to need protection against the SET ROLE issue. GUC changes are still allowed, since there are many useful cases for that, but we prevent security problems by forcing a rollback of any GUC change after completing the operation. Other cases are handled by throwing an error if any change is attempted; these include temp table creation, closing a cursor, and creating or deleting a prepared statement. (In 7.4, the infrastructure to roll back GUC changes doesn't exist, so we settle for rejecting changes of "search_path" in these contexts.) Original report and patch by Gurjeet Singh, additional analysis by Tom Lane. Security: CVE-2009-4136
Tom Lane authoredan allegedly immutable index function. It was previously recognized that we had to prevent such a function from executing SET/RESET ROLE/SESSION AUTHORIZATION, or it could trivially obtain the privileges of the session user. However, since there is in general no privilege checking for changes of session-local state, it is also possible for such a function to change settings in a way that might subvert later operations in the same session. Examples include changing search_path to cause an unexpected function to be called, or replacing an existing prepared statement with another one that will execute a function of the attacker's choosing. The present patch secures VACUUM, ANALYZE, and CREATE INDEX/REINDEX against these threats, which are the same places previously deemed to need protection against the SET ROLE issue. GUC changes are still allowed, since there are many useful cases for that, but we prevent security problems by forcing a rollback of any GUC change after completing the operation. Other cases are handled by throwing an error if any change is attempted; these include temp table creation, closing a cursor, and creating or deleting a prepared statement. (In 7.4, the infrastructure to roll back GUC changes doesn't exist, so we settle for rejecting changes of "search_path" in these contexts.) Original report and patch by Gurjeet Singh, additional analysis by Tom Lane. Security: CVE-2009-4136
schemacmds.c 11.80 KiB
/*-------------------------------------------------------------------------
*
* schemacmds.c
* schema creation/manipulation commands
*
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/schemacmds.c,v 1.54 2009/12/09 21:57:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_namespace.h"
#include "commands/dbcommands.h"
#include "commands/schemacmds.h"
#include "miscadmin.h"
#include "parser/parse_utilcmd.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId);
/*
* CREATE SCHEMA
*/
void
CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString)
{
const char *schemaName = stmt->schemaname;
const char *authId = stmt->authid;
Oid namespaceId;
OverrideSearchPath *overridePath;
List *parsetree_list;
ListCell *parsetree_item;
Oid owner_uid;
Oid saved_uid;
int save_sec_context;
AclResult aclresult;
GetUserIdAndSecContext(&saved_uid, &save_sec_context);
/*
* Who is supposed to own the new schema?
*/
if (authId)
owner_uid = get_roleid_checked(authId);
else
owner_uid = saved_uid;
/*
* To create a schema, must have schema-create privilege on the current
* database and must be able to become the target role (this does not
* imply that the target role itself must have create-schema privilege).
* The latter provision guards against "giveaway" attacks. Note that a
* superuser will always have both of these privileges a fortiori.
*/ aclresult = pg_database_aclcheck(MyDatabaseId, saved_uid, ACL_CREATE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_DATABASE,
get_database_name(MyDatabaseId));
check_is_member_of_role(saved_uid, owner_uid);
/* Additional check to protect reserved schema names */
if (!allowSystemTableMods && IsReservedName(schemaName))
ereport(ERROR,
(errcode(ERRCODE_RESERVED_NAME),
errmsg("unacceptable schema name \"%s\"", schemaName),
errdetail("The prefix \"pg_\" is reserved for system schemas.")));
/*
* If the requested authorization is different from the current user,
* temporarily set the current user so that the object(s) will be created
* with the correct ownership.
*
* (The setting will be restored at the end of this routine, or in case of
* error, transaction abort will clean things up.)
*/
if (saved_uid != owner_uid)
SetUserIdAndSecContext(owner_uid,
save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
/* Create the schema's namespace */
namespaceId = NamespaceCreate(schemaName, owner_uid);
/* Advance cmd counter to make the namespace visible */
CommandCounterIncrement();
/*
* Temporarily make the new namespace be the front of the search path, as
* well as the default creation target namespace. This will be undone at
* the end of this routine, or upon error.
*/
overridePath = GetOverrideSearchPath(CurrentMemoryContext);
overridePath->schemas = lcons_oid(namespaceId, overridePath->schemas);
/* XXX should we clear overridePath->useTemp? */
PushOverrideSearchPath(overridePath);
/*
* Examine the list of commands embedded in the CREATE SCHEMA command, and
* reorganize them into a sequentially executable order with no forward
* references. Note that the result is still a list of raw parsetrees ---
* we cannot, in general, run parse analysis on one statement until we
* have actually executed the prior ones.
*/
parsetree_list = transformCreateSchemaStmt(stmt);
/*
* Execute each command contained in the CREATE SCHEMA. Since the grammar
* allows only utility commands in CREATE SCHEMA, there is no need to pass
* them through parse_analyze() or the rewriter; we can just hand them
* straight to ProcessUtility.
*/
foreach(parsetree_item, parsetree_list)
{
Node *stmt = (Node *) lfirst(parsetree_item);
/* do this step */
ProcessUtility(stmt,
queryString,
NULL,
false, /* not top level */
None_Receiver,
NULL);
/* make sure later steps can see the object created here */
CommandCounterIncrement(); }
/* Reset search path to normal state */
PopOverrideSearchPath();
/* Reset current user and security context */
SetUserIdAndSecContext(saved_uid, save_sec_context);
}
/*
* RemoveSchemas
* Implements DROP SCHEMA.
*/
void
RemoveSchemas(DropStmt *drop)
{
ObjectAddresses *objects;
ListCell *cell;
/*
* First we identify all the schemas, then we delete them in a single
* performMultipleDeletions() call. This is to avoid unwanted DROP
* RESTRICT errors if one of the schemas depends on another.
*/
objects = new_object_addresses();
foreach(cell, drop->objects)
{
List *names = (List *) lfirst(cell);
char *namespaceName;
Oid namespaceId;
ObjectAddress object;
if (list_length(names) != 1)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("schema name cannot be qualified")));
namespaceName = strVal(linitial(names));
namespaceId = GetSysCacheOid(NAMESPACENAME,
CStringGetDatum(namespaceName),
0, 0, 0);
if (!OidIsValid(namespaceId))
{
if (!drop->missing_ok)
{
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_SCHEMA),
errmsg("schema \"%s\" does not exist",
namespaceName)));
}
else
{
ereport(NOTICE,
(errmsg("schema \"%s\" does not exist, skipping",
namespaceName)));
}
continue;
}
/* Permission check */
if (!pg_namespace_ownercheck(namespaceId, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_NAMESPACE,
namespaceName);
object.classId = NamespaceRelationId;
object.objectId = namespaceId;
object.objectSubId = 0;
add_exact_object_address(&object, objects);
}
/*
* Do the deletions. Objects contained in the schema(s) are removed by
* means of their dependency links to the schema.
*/
performMultipleDeletions(objects, drop->behavior);
free_object_addresses(objects);
}
/*
* Guts of schema deletion.
*/
void
RemoveSchemaById(Oid schemaOid)
{
Relation relation;
HeapTuple tup;
relation = heap_open(NamespaceRelationId, RowExclusiveLock);
tup = SearchSysCache(NAMESPACEOID,
ObjectIdGetDatum(schemaOid),
0, 0, 0);
if (!HeapTupleIsValid(tup)) /* should not happen */
elog(ERROR, "cache lookup failed for namespace %u", schemaOid);
simple_heap_delete(relation, &tup->t_self);
ReleaseSysCache(tup);
heap_close(relation, RowExclusiveLock);
}
/*
* Rename schema
*/
void
RenameSchema(const char *oldname, const char *newname)
{
HeapTuple tup;
Relation rel;
AclResult aclresult;
rel = heap_open(NamespaceRelationId, RowExclusiveLock);
tup = SearchSysCacheCopy(NAMESPACENAME,
CStringGetDatum(oldname),
0, 0, 0);
if (!HeapTupleIsValid(tup))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_SCHEMA),
errmsg("schema \"%s\" does not exist", oldname)));
/* make sure the new name doesn't exist */
if (HeapTupleIsValid(
SearchSysCache(NAMESPACENAME,
CStringGetDatum(newname),
0, 0, 0)))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_SCHEMA),
errmsg("schema \"%s\" already exists", newname)));
/* must be owner */
if (!pg_namespace_ownercheck(HeapTupleGetOid(tup), GetUserId())) aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_NAMESPACE,
oldname);
/* must have CREATE privilege on database */
aclresult = pg_database_aclcheck(MyDatabaseId, GetUserId(), ACL_CREATE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_DATABASE,
get_database_name(MyDatabaseId));
if (!allowSystemTableMods && IsReservedName(newname))
ereport(ERROR,
(errcode(ERRCODE_RESERVED_NAME),
errmsg("unacceptable schema name \"%s\"", newname),
errdetail("The prefix \"pg_\" is reserved for system schemas.")));
/* rename */
namestrcpy(&(((Form_pg_namespace) GETSTRUCT(tup))->nspname), newname);
simple_heap_update(rel, &tup->t_self, tup);
CatalogUpdateIndexes(rel, tup);
heap_close(rel, NoLock);
heap_freetuple(tup);
}
void
AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
{
HeapTuple tup;
Relation rel;
rel = heap_open(NamespaceRelationId, RowExclusiveLock);
tup = SearchSysCache(NAMESPACEOID,
ObjectIdGetDatum(oid),
0, 0, 0);
if (!HeapTupleIsValid(tup))
elog(ERROR, "cache lookup failed for schema %u", oid);
AlterSchemaOwner_internal(tup, rel, newOwnerId);
ReleaseSysCache(tup);
heap_close(rel, RowExclusiveLock);
}
/*
* Change schema owner
*/
void
AlterSchemaOwner(const char *name, Oid newOwnerId)
{
HeapTuple tup;
Relation rel;
rel = heap_open(NamespaceRelationId, RowExclusiveLock);
tup = SearchSysCache(NAMESPACENAME,
CStringGetDatum(name),
0, 0, 0);
if (!HeapTupleIsValid(tup))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_SCHEMA),
errmsg("schema \"%s\" does not exist", name)));
AlterSchemaOwner_internal(tup, rel, newOwnerId);
ReleaseSysCache(tup);
heap_close(rel, RowExclusiveLock);}
static void
AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId)
{
Form_pg_namespace nspForm;
Assert(tup->t_tableOid == NamespaceRelationId);
Assert(RelationGetRelid(rel) == NamespaceRelationId);
nspForm = (Form_pg_namespace) GETSTRUCT(tup);
/*
* If the new owner is the same as the existing owner, consider the
* command to have succeeded. This is for dump restoration purposes.
*/
if (nspForm->nspowner != newOwnerId)
{
Datum repl_val[Natts_pg_namespace];
bool repl_null[Natts_pg_namespace];
bool repl_repl[Natts_pg_namespace];
Acl *newAcl;
Datum aclDatum;
bool isNull;
HeapTuple newtuple;
AclResult aclresult;
/* Otherwise, must be owner of the existing object */
if (!pg_namespace_ownercheck(HeapTupleGetOid(tup), GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_NAMESPACE,
NameStr(nspForm->nspname));
/* Must be able to become new owner */
check_is_member_of_role(GetUserId(), newOwnerId);
/*
* must have create-schema rights
*
* NOTE: This is different from other alter-owner checks in that the
* current user is checked for create privileges instead of the
* destination owner. This is consistent with the CREATE case for
* schemas. Because superusers will always have this right, we need
* no special case for them.
*/
aclresult = pg_database_aclcheck(MyDatabaseId, GetUserId(),
ACL_CREATE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_DATABASE,
get_database_name(MyDatabaseId));
memset(repl_null, false, sizeof(repl_null));
memset(repl_repl, false, sizeof(repl_repl));
repl_repl[Anum_pg_namespace_nspowner - 1] = true;
repl_val[Anum_pg_namespace_nspowner - 1] = ObjectIdGetDatum(newOwnerId);
/*
* Determine the modified ACL for the new owner. This is only
* necessary when the ACL is non-null.
*/
aclDatum = SysCacheGetAttr(NAMESPACENAME, tup,
Anum_pg_namespace_nspacl,
&isNull);
if (!isNull)
{
newAcl = aclnewowner(DatumGetAclP(aclDatum),
nspForm->nspowner, newOwnerId);
repl_repl[Anum_pg_namespace_nspacl - 1] = true;
repl_val[Anum_pg_namespace_nspacl - 1] = PointerGetDatum(newAcl);
}
newtuple = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null, repl_repl);
simple_heap_update(rel, &newtuple->t_self, newtuple);
CatalogUpdateIndexes(rel, newtuple);
heap_freetuple(newtuple);
/* Update owner dependency reference */
changeDependencyOnOwner(NamespaceRelationId, HeapTupleGetOid(tup),
newOwnerId);
}
}