Age         Owner                  TLA  Line data    Source code

                                  1                 : /*-------------------------------------------------------------------------
                                  2                 :  *
                                  3                 :  * usercontext.c
                                  4                 :  *    Convenience functions for running code as a different database user.
                                  5                 :  *
                                  6                 :  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
                                  7                 :  * Portions Copyright (c) 1994, Regents of the University of California
                                  8                 :  *
                                  9                 :  *
                                 10                 :  * IDENTIFICATION
                                 11                 :  *    src/backend/utils/init/usercontext.c
                                 12                 :  *
                                 13                 :  *-------------------------------------------------------------------------
                                 14                 :  */
                                 15                 : #include "postgres.h"
                                 16                 : 
                                 17                 : #include "miscadmin.h"
                                 18                 : #include "utils/acl.h"
                                 19                 : #include "utils/guc.h"
                                 20                 : #include "utils/usercontext.h"
                                 21                 : 
                                 22                 : /*
                                 23                 :  * Temporarily switch to a new user ID.
                                 24                 :  *
                                 25                 :  * If the current user doesn't have permission to SET ROLE to the new user,
                                 26                 :  * an ERROR occurs.
                                 27                 :  *
                                 28                 :  * If the new user doesn't have permission to SET ROLE to the current user,
                                 29                 :  * SECURITY_RESTRICTED_OPERATION is imposed and a new GUC nest level is
                                 30                 :  * created so that any settings changes can be rolled back.
                                 31                 :  */
                                 32                 : void
    5 rhaas                      33 GNC      147872 : SwitchToUntrustedUser(Oid userid, UserContext *context)
                                 34                 : {
                                 35                 :     /* Get the current user ID and security context. */
                                 36          147872 :     GetUserIdAndSecContext(&context->save_userid,
                                 37                 :                            &context->save_sec_context);
                                 38                 : 
                                 39                 :     /* Check that we have sufficient privileges to assume the target role. */
                                 40          147872 :     if (!member_can_set_role(context->save_userid, userid))
                                 41               2 :         ereport(ERROR,
                                 42                 :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 43                 :                  errmsg("role \"%s\" cannot SET ROLE to \"%s\"",
                                 44                 :                         GetUserNameFromId(context->save_userid, false),
                                 45                 :                         GetUserNameFromId(userid, false))));
                                 46                 : 
                                 47                 :     /*
                                 48                 :      * Try to prevent the user to which we're switching from assuming the
                                 49                 :      * privileges of the current user, unless they can SET ROLE to that user
                                 50                 :      * anyway.
                                 51                 :      */
                                 52          147870 :     if (member_can_set_role(userid, context->save_userid))
                                 53                 :     {
                                 54                 :         /*
                                 55                 :          * Each user can SET ROLE to the other, so there's no point in
                                 56                 :          * imposing any security restrictions. Just let the user do whatever
                                 57                 :          * they want.
                                 58                 :          */
                                 59          147844 :         SetUserIdAndSecContext(userid, context->save_sec_context);
                                 60          147844 :         context->save_nestlevel = -1;
                                 61                 :     }
                                 62                 :     else
                                 63                 :     {
                                 64              26 :         int sec_context = context->save_sec_context;
                                 65                 : 
                                 66                 :         /*
                                 67                 :          * This user can SET ROLE to the target user, but not the other way
                                 68                 :          * around, so protect ourselves against the target user by setting
                                 69                 :          * SECURITY_RESTRICTED_OPERATION to prevent certain changes to the
                                 70                 :          * session state. Also set up a new GUC nest level, so that we can roll
                                 71                 :          * back any GUC changes that may be made by code running as the target
                                 72                 :          * user, inasmuch as they could be malicious.
                                 73                 :          */
                                 74              26 :         sec_context |= SECURITY_RESTRICTED_OPERATION;
                                 75              26 :         SetUserIdAndSecContext(userid, sec_context);
                                 76              26 :         context->save_nestlevel = NewGUCNestLevel();
                                 77                 :     }
                                 78          147870 : }
                                 79                 : 
                                 80                 : /*
                                 81                 :  * Switch back to the original user ID.
                                 82                 :  *
                                 83                 :  * If we created a new GUC nest level, also roll back any changes that were
                                 84                 :  * made within it.
                                 85                 :  */
                                 86                 : void
                                 87          147855 : RestoreUserContext(UserContext *context)
                                 88                 : {
                                 89          147855 :     if (context->save_nestlevel != -1)
                                 90              20 :         AtEOXact_GUC(false, context->save_nestlevel);
                                 91          147855 :     SetUserIdAndSecContext(context->save_userid, context->save_sec_context);
                                 92          147855 : }