database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-27 12:41:57 +03:00
Code Activity

Prevent indirect security attacks via changing session-local state within

Browse Source 
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
This commit is contained in:
Tom Lane
2009-12-09 21:57:51 +00:00
parent 7aeaa97de2
commit 62aba76568
14 changed files with 278 additions and 109 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
src/backend/tcop/utility.c
View File

@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.321 2009/12/07 05:22:22 tgl Exp $
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.322 2009/12/09 21:57:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -225,6 +225,25 @@ check_xact_readonly(Node *parsetree)
}
/*
* CheckRestrictedOperation: throw error for hazardous command if we're
* inside a security restriction context.
*
* This is needed to protect session-local state for which there is not any
* better-defined protection mechanism, such as ownership.
*/
static void
CheckRestrictedOperation(const char *cmdname)
{
if (InSecurityRestrictedOperation())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
/* translator: %s is name of a SQL command, eg PREPARE */
errmsg("cannot execute %s within security-restricted operation",
cmdname)));
}
/*
* ProcessUtility
* general utility function invoker
@ -390,6 +409,7 @@ ProcessUtility(Node *parsetree,
{
ClosePortalStmt *stmt = (ClosePortalStmt *) parsetree;
CheckRestrictedOperation("CLOSE");
PerformPortalClose(stmt->portalname);
}
break;
@ -586,6 +606,7 @@ ProcessUtility(Node *parsetree,
break;
case T_PrepareStmt:
CheckRestrictedOperation("PREPARE");
PrepareQuery((PrepareStmt *) parsetree, queryString);
break;
@ -595,6 +616,7 @@ ProcessUtility(Node *parsetree,
break;
case T_DeallocateStmt:
CheckRestrictedOperation("DEALLOCATE");
DeallocateQuery((DeallocateStmt *) parsetree);
break;
@ -885,6 +907,7 @@ ProcessUtility(Node *parsetree,
{
ListenStmt *stmt = (ListenStmt *) parsetree;
CheckRestrictedOperation("LISTEN");
Async_Listen(stmt->conditionname);
}
break;
@ -893,6 +916,7 @@ ProcessUtility(Node *parsetree,
{
UnlistenStmt *stmt = (UnlistenStmt *) parsetree;
CheckRestrictedOperation("UNLISTEN");
if (stmt->conditionname)
Async_Unlisten(stmt->conditionname);
else
@ -936,6 +960,8 @@ ProcessUtility(Node *parsetree,
break;
case T_DiscardStmt:
/* should we allow DISCARD PLANS? */
CheckRestrictedOperation("DISCARD");
DiscardCommand((DiscardStmt *) parsetree, isTopLevel);
break;