From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262489AbTHUHjX (ORCPT ); Thu, 21 Aug 2003 03:39:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262491AbTHUHjX (ORCPT ); Thu, 21 Aug 2003 03:39:23 -0400 Received: from adsl-206-170-148-147.dsl.snfc21.pacbell.net ([206.170.148.147]:25869 "EHLO gw.goop.org") by vger.kernel.org with ESMTP id S262489AbTHUHjV (ORCPT ); Thu, 21 Aug 2003 03:39:21 -0400 Subject: [PATCH] Allow either tid or pid in SCM_CREDENTIALS struct ucred From: Jeremy Fitzhardinge To: Andrew Morton , kuznet@ms2.inr.ac.ru Cc: linux-kernel Content-Type: text/plain Message-Id: <1061451559.4386.13.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.4 Date: Thu, 21 Aug 2003 00:39:19 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew, Could you stick this in -mm and see if anyone complains? It fixes an apparent bug in the validation of the SCM_CREDENTIALS structure in a unix-domain socket sendmsg(). I found this because with Valgrind, the sendmsg call is being done in a different thread from the one which did a getpid() to fill out the SCM_CREDENTIALS structure, which causes the kernel to fail the sendmsg with EPERM. In the general case, this would cause a multithreaded program sending messages with SCM_CREDENTIALS to appear schizophrenic to a recipient, because every message would have a different pid depending on which thread happened to send it. If you use SCM_CREDENTIALS with a unix domain socket, and you're non-root, then the kernel double-checks the values you supply for pid, uid and gid in struct ucred. In the case of uid or gid, it allows any of effective, saved or real uid/gid. In the case of pid, it only allows current->pid, which is actually the tid. This patch also makes it accept tgid in the SCM_CREDENTIALS pid field. That is, a threaded program can either supply the ID of the whole process (tgid) or a particular thread (pid). Thanks, J net/core/scm.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-) diff -puN net/core/scm.c~scm_allow_tgid net/core/scm.c --- local-2.6/net/core/scm.c~scm_allow_tgid 2003-08-20 19:52:40.000000000 -0700 +++ local-2.6-jeremy/net/core/scm.c 2003-08-21 00:28:10.295629745 -0700 @@ -41,7 +41,8 @@ static __inline__ int scm_check_creds(struct ucred *creds) { - if ((creds->pid == current->pid || capable(CAP_SYS_ADMIN)) && + if (((creds->pid == current->pid || creds->pid == current->tgid) || + capable(CAP_SYS_ADMIN)) && ((creds->uid == current->uid || creds->uid == current->euid || creds->uid == current->suid) || capable(CAP_SETUID)) && ((creds->gid == current->gid || creds->gid == current->egid || _