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Make standard maintenance operations (including VACUUM, ANALYZE, REINDEX,
and CLUSTER) execute as the table owner rather than the calling user, using the same privilege-switching mechanism already used for SECURITY DEFINER functions. The purpose of this change is to ensure that user-defined functions used in index definitions cannot acquire the privileges of a superuser account that is performing routine maintenance. While a function used in an index is supposed to be IMMUTABLE and thus not able to do anything very interesting, there are several easy ways around that restriction; and even if we could plug them all, there would remain a risk of reading sensitive information and broadcasting it through a covert channel such as CPU usage. To prevent bypassing this security measure, execution of SET SESSION AUTHORIZATION and SET ROLE is now forbidden within a SECURITY DEFINER context. Thanks to Itagaki Takahiro for reporting this vulnerability. Security: CVE-2007-6600
This commit is contained in:
Tom Lane
@ -1,4 +1,4 @@
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_session_auth.sgml,v 1.11 2003/09/11 21:42:20 momjian Exp $ -->
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_session_auth.sgml,v 1.11.2.1 2008/01/03 21:25:33 tgl Exp $ -->
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<refentry id="SQL-SET-SESSION-AUTHORIZATION">
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<refmeta>
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<refentrytitle id="sql-set-session-authorization-title">SET SESSION AUTHORIZATION</refentrytitle>
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@ -27,7 +27,7 @@ RESET SESSION AUTHORIZATION
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<para>
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This command sets the session user identifier and the current user
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identifier of the current SQL-session context to be <replaceable
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identifier of the current SQL session to be <replaceable
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class="parameter">username</replaceable>. The user name may be
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written as either an identifier or a string literal. Using this
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command, it is possible, for example, to temporarily become an
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@ -38,7 +38,7 @@ RESET SESSION AUTHORIZATION
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The session user identifier is initially set to be the (possibly
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authenticated) user name provided by the client. The current user
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identifier is normally equal to the session user identifier, but
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may change temporarily in the context of <quote>setuid</quote>
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might change temporarily in the context of <literal>SECURITY DEFINER</>
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functions and similar mechanisms. The current user identifier is
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relevant for permission checking.
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</para>
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@ -63,6 +63,15 @@ RESET SESSION AUTHORIZATION
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</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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<command>SET SESSION AUTHORIZATION</> cannot be used within a
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<literal>SECURITY DEFINER</> function.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.156.2.4 2007/04/26 23:25:40 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.156.2.5 2008/01/03 21:25:33 tgl Exp $
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*
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* NOTES
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* Transaction aborts can now occur two ways:
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@ -204,6 +204,8 @@ static TransactionStateData CurrentTransactionStateData = {
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static TransactionState CurrentTransactionState = &CurrentTransactionStateData;
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static AclId prevUser; /* CurrentUserId at transaction start */
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/*
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* User-tweakable parameters
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*/
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@ -849,6 +851,7 @@ static void
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StartTransaction(void)
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{
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TransactionState s = CurrentTransactionState;
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bool prevSecDefCxt;
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/*
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* check the current transaction state
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@ -882,6 +885,10 @@ StartTransaction(void)
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s->commandId = FirstCommandId;
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s->startTime = GetCurrentAbsoluteTimeUsec(&(s->startTimeUsec));
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GetUserIdAndContext(&prevUser, &prevSecDefCxt);
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/* SecurityDefinerContext should never be set outside a transaction */
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Assert(!prevSecDefCxt);
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/*
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* initialize the various transaction subsystems
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*/
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@ -1074,9 +1081,16 @@ AbortTransaction(void)
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AtAbort_Memory();
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/*
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* Reset user id which might have been changed transiently
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* Reset user ID which might have been changed transiently. We need this
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* to clean up in case control escaped out of a SECURITY DEFINER function
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* or other local change of CurrentUserId; therefore, the prior value
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* of SecurityDefinerContext also needs to be restored.
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*
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* (Note: it is not necessary to restore session authorization
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* setting here because that can only be changed via GUC, and GUC will
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* take care of rolling it back if need be.)
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*/
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SetUserId(GetSessionUserId());
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SetUserIdAndContext(prevUser, false);
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/*
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* do abort processing
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.219.2.2 2007/11/08 23:23:23 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.219.2.3 2008/01/03 21:25:33 tgl Exp $
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*
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*
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* INTERFACE ROUTINES
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@ -1332,6 +1332,8 @@ index_build(Relation heapRelation,
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IndexInfo *indexInfo)
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{
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RegProcedure procedure;
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AclId save_userid;
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bool save_secdefcxt;
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/*
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* sanity checks
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@ -1342,6 +1344,13 @@ index_build(Relation heapRelation,
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procedure = indexRelation->rd_am->ambuild;
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Assert(RegProcedureIsValid(procedure));
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/*
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* Switch to the table owner's userid, so that any index functions are
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* run as that user.
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*/
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GetUserIdAndContext(&save_userid, &save_secdefcxt);
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SetUserIdAndContext(heapRelation->rd_rel->relowner, true);
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/*
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* Call the access method's build procedure
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*/
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@ -1349,6 +1358,9 @@ index_build(Relation heapRelation,
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PointerGetDatum(heapRelation),
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PointerGetDatum(indexRelation),
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PointerGetDatum(indexInfo));
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/* Restore userid */
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SetUserIdAndContext(save_userid, save_secdefcxt);
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}
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/schemacmds.c,v 1.16 2003/08/04 02:39:58 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/schemacmds.c,v 1.16.4.1 2008/01/03 21:25:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -46,9 +46,10 @@ CreateSchemaCommand(CreateSchemaStmt *stmt)
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const char *owner_name;
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AclId owner_userid;
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AclId saved_userid;
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bool saved_secdefcxt;
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AclResult aclresult;
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saved_userid = GetUserId();
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GetUserIdAndContext(&saved_userid, &saved_secdefcxt);
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/*
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* Figure out user identities.
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@ -71,7 +72,7 @@ CreateSchemaCommand(CreateSchemaStmt *stmt)
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* (This will revert to session user on error or at the end of
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* this routine.)
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*/
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SetUserId(owner_userid);
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SetUserIdAndContext(owner_userid, true);
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}
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else
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{
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@ -151,7 +152,7 @@ CreateSchemaCommand(CreateSchemaStmt *stmt)
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PopSpecialNamespace(namespaceId);
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/* Reset current user */
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SetUserId(saved_userid);
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SetUserIdAndContext(saved_userid, saved_secdefcxt);
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}
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@ -13,7 +13,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.263.2.3 2007/03/14 18:49:26 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.263.2.4 2008/01/03 21:25:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -742,6 +742,8 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
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LockRelId onerelid;
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Oid toast_relid;
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bool result;
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AclId save_userid;
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bool save_secdefcxt;
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/* Begin a transaction for vacuuming this relation */
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StartTransactionCommand();
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@ -846,6 +848,14 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
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*/
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toast_relid = onerel->rd_rel->reltoastrelid;
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/*
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* Switch to the table owner's userid, so that any index functions are
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* run as that user. (This is unnecessary, but harmless, for lazy
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* VACUUM.)
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*/
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GetUserIdAndContext(&save_userid, &save_secdefcxt);
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SetUserIdAndContext(onerel->rd_rel->relowner, true);
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/*
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* Do the actual work --- either FULL or "lazy" vacuum
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*/
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@ -856,6 +866,9 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
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result = true; /* did the vacuum */
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/* Restore userid */
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SetUserIdAndContext(save_userid, save_secdefcxt);
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/* all done with this class, but hold lock until commit */
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relation_close(onerel, NoLock);
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@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/variable.c,v 1.88.2.3 2006/02/12 22:33:28 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/variable.c,v 1.88.2.4 2008/01/03 21:25:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -773,6 +773,22 @@ assign_session_authorization(const char *value, bool doit, bool interactive)
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/* not a saved ID, so look it up */
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HeapTuple userTup;
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if (InSecurityDefinerContext())
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{
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/*
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* Disallow SET SESSION AUTHORIZATION inside a security definer
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* context. We need to do this because when we exit the context,
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* GUC won't be notified, leaving things out of sync. Note that
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* this test is positioned so that restoring a previously saved
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* setting isn't prevented.
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*/
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if (interactive)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot set session authorization within security-definer function")));
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return NULL;
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}
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if (!IsTransactionState())
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{
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/*
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@ -17,7 +17,7 @@
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*
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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*
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/ri_triggers.c,v 1.63.2.1 2004/10/13 22:22:03 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/ri_triggers.c,v 1.63.2.2 2008/01/03 21:25:33 tgl Exp $
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*
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* ----------
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*/
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@ -2967,7 +2967,8 @@ ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
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{
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void *qplan;
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Relation query_rel;
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AclId save_uid;
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AclId save_userid;
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bool save_secdefcxt;
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/*
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* The query is always run against the FK table except when this is an
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@ -2981,8 +2982,8 @@ ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
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query_rel = fk_rel;
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/* Switch to proper UID to perform check as */
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save_uid = GetUserId();
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SetUserId(RelationGetForm(query_rel)->relowner);
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GetUserIdAndContext(&save_userid, &save_secdefcxt);
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SetUserIdAndContext(RelationGetForm(query_rel)->relowner, true);
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/* Create the plan */
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qplan = SPI_prepare(querystr, nargs, argtypes);
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@ -2991,7 +2992,7 @@ ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
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elog(ERROR, "SPI_prepare returned %d for %s", SPI_result, querystr);
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/* Restore UID */
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SetUserId(save_uid);
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SetUserIdAndContext(save_userid, save_secdefcxt);
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/* Save the plan if requested */
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if (cache_plan)
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@ -3019,7 +3020,8 @@ ri_PerformCheck(RI_QueryKey *qkey, void *qplan,
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bool useCurrentSnapshot;
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int limit;
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int spi_result;
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AclId save_uid;
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AclId save_userid;
|
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bool save_secdefcxt;
|
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Datum vals[RI_MAX_NUMKEYS * 2];
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char nulls[RI_MAX_NUMKEYS * 2];
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|
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@ -3095,15 +3097,15 @@ ri_PerformCheck(RI_QueryKey *qkey, void *qplan,
|
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limit = (expect_OK == SPI_OK_SELECT) ? 1 : 0;
|
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|
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/* Switch to proper UID to perform check as */
|
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save_uid = GetUserId();
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SetUserId(RelationGetForm(query_rel)->relowner);
|
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GetUserIdAndContext(&save_userid, &save_secdefcxt);
|
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SetUserIdAndContext(RelationGetForm(query_rel)->relowner, true);
|
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|
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/* Finally we can run the query. */
|
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spi_result = SPI_execp_current(qplan, vals, nulls,
|
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useCurrentSnapshot, limit);
|
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|
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/* Restore UID */
|
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SetUserId(save_uid);
|
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SetUserIdAndContext(save_userid, save_secdefcxt);
|
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|
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/* Check result */
|
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if (spi_result < 0)
|
||||
|
||||
@ -8,7 +8,7 @@
|
||||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/fmgr/fmgr.c,v 1.76.2.1 2007/07/31 15:50:17 tgl Exp $
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/fmgr/fmgr.c,v 1.76.2.2 2008/01/03 21:25:33 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
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@ -654,6 +654,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
|
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FmgrInfo *save_flinfo;
|
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struct fmgr_security_definer_cache *fcache;
|
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AclId save_userid;
|
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bool save_secdefcxt;
|
||||
HeapTuple tuple;
|
||||
|
||||
if (!fcinfo->flinfo->fn_extra)
|
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@ -679,16 +680,18 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
|
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else
|
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fcache = fcinfo->flinfo->fn_extra;
|
||||
|
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GetUserIdAndContext(&save_userid, &save_secdefcxt);
|
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SetUserIdAndContext(fcache->userid, true);
|
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|
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save_flinfo = fcinfo->flinfo;
|
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fcinfo->flinfo = &fcache->flinfo;
|
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|
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save_userid = GetUserId();
|
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SetUserId(fcache->userid);
|
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result = FunctionCallInvoke(fcinfo);
|
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SetUserId(save_userid);
|
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|
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fcinfo->flinfo = save_flinfo;
|
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|
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SetUserIdAndContext(save_userid, save_secdefcxt);
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
|
||||
@ -8,7 +8,7 @@
|
||||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.116 2003/09/26 15:27:37 petere Exp $
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.116.2.1 2008/01/03 21:25:33 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
@ -235,6 +235,9 @@ SetDataDir(const char *dir)
|
||||
* are implemented. Conceptually there is a stack, whose bottom
|
||||
* is the session user. You are yourself responsible to save and
|
||||
* restore the current user id if you need to change it.
|
||||
*
|
||||
* SecurityDefinerContext is TRUE if we are within a SECURITY DEFINER function
|
||||
* or another context that temporarily changes CurrentUserId.
|
||||
* ----------------------------------------------------------------
|
||||
*/
|
||||
static AclId AuthenticatedUserId = 0;
|
||||
@ -243,8 +246,13 @@ static AclId CurrentUserId = 0;
|
||||
|
||||
static bool AuthenticatedUserIsSuperuser = false;
|
||||
|
||||
static bool SecurityDefinerContext = false;
|
||||
|
||||
|
||||
/*
|
||||
* This function is relevant for all privilege checks.
|
||||
* GetUserId - get the current effective user ID.
|
||||
*
|
||||
* Note: there's no SetUserId() anymore; use SetUserIdAndContext().
|
||||
*/
|
||||
AclId
|
||||
GetUserId(void)
|
||||
@ -254,14 +262,6 @@ GetUserId(void)
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
SetUserId(AclId newid)
|
||||
{
|
||||
AssertArg(AclIdIsValid(newid));
|
||||
CurrentUserId = newid;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* This value is only relevant for informational purposes.
|
||||
*/
|
||||
@ -273,17 +273,57 @@ GetSessionUserId(void)
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
static void
|
||||
SetSessionUserId(AclId newid)
|
||||
{
|
||||
AssertState(!SecurityDefinerContext);
|
||||
AssertArg(AclIdIsValid(newid));
|
||||
SessionUserId = newid;
|
||||
/* Current user defaults to session user. */
|
||||
if (!AclIdIsValid(CurrentUserId))
|
||||
CurrentUserId = newid;
|
||||
CurrentUserId = newid;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* GetUserIdAndContext/SetUserIdAndContext - get/set the current user ID
|
||||
* and the SecurityDefinerContext flag.
|
||||
*
|
||||
* Unlike GetUserId, GetUserIdAndContext does *not* Assert that the current
|
||||
* value of CurrentUserId is valid; nor does SetUserIdAndContext require
|
||||
* the new value to be valid. In fact, these routines had better not
|
||||
* ever throw any kind of error. This is because they are used by
|
||||
* StartTransaction and AbortTransaction to save/restore the settings,
|
||||
* and during the first transaction within a backend, the value to be saved
|
||||
* and perhaps restored is indeed invalid. We have to be able to get
|
||||
* through AbortTransaction without asserting in case InitPostgres fails.
|
||||
*/
|
||||
void
|
||||
GetUserIdAndContext(AclId *userid, bool *sec_def_context)
|
||||
{
|
||||
*userid = CurrentUserId;
|
||||
*sec_def_context = SecurityDefinerContext;
|
||||
}
|
||||
|
||||
void
|
||||
SetUserIdAndContext(AclId userid, bool sec_def_context)
|
||||
{
|
||||
CurrentUserId = userid;
|
||||
SecurityDefinerContext = sec_def_context;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* InSecurityDefinerContext - are we inside a SECURITY DEFINER context?
|
||||
*/
|
||||
bool
|
||||
InSecurityDefinerContext(void)
|
||||
{
|
||||
return SecurityDefinerContext;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Initialize user identity during normal backend startup
|
||||
*/
|
||||
void
|
||||
InitializeSessionUserId(const char *username)
|
||||
{
|
||||
@ -378,7 +418,6 @@ SetSessionAuthorization(AclId userid, bool is_superuser)
|
||||
errmsg("permission denied to set session authorization")));
|
||||
|
||||
SetSessionUserId(userid);
|
||||
SetUserId(userid);
|
||||
|
||||
SetConfigOption("is_superuser",
|
||||
is_superuser ? "on" : "off",
|
||||
|
||||
@ -12,7 +12,7 @@
|
||||
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $Id: miscadmin.h,v 1.134 2003/09/24 18:54:01 tgl Exp $
|
||||
* $Id: miscadmin.h,v 1.134.2.1 2008/01/03 21:25:34 tgl Exp $
|
||||
*
|
||||
* NOTES
|
||||
* some of the information in this file should be moved to
|
||||
@ -220,9 +220,10 @@ extern void SetDatabasePath(const char *path);
|
||||
|
||||
extern char *GetUserNameFromId(AclId userid);
|
||||
extern AclId GetUserId(void);
|
||||
extern void SetUserId(AclId userid);
|
||||
extern AclId GetSessionUserId(void);
|
||||
extern void SetSessionUserId(AclId userid);
|
||||
extern void GetUserIdAndContext(AclId *userid, bool *sec_def_context);
|
||||
extern void SetUserIdAndContext(AclId userid, bool sec_def_context);
|
||||
extern bool InSecurityDefinerContext(void);
|
||||
extern void InitializeSessionUserId(const char *username);
|
||||
extern void InitializeSessionUserIdStandalone(void);
|
||||
extern void SetSessionAuthorization(AclId userid, bool is_superuser);
|
||||
|
||||
Reference in New Issue
Block a user