From patchwork Fri Feb 14 18:35:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11383045 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7728213A4 for ; Fri, 14 Feb 2020 18:38:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56986222C2 for ; Fri, 14 Feb 2020 18:38:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390362AbgBNSil (ORCPT ); Fri, 14 Feb 2020 13:38:41 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:33678 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730588AbgBNSiC (ORCPT ); Fri, 14 Feb 2020 13:38:02 -0500 Received: from ip5f5bf7ec.dynamic.kabel-deutschland.de ([95.91.247.236] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1j2fqQ-0000uO-N8; Fri, 14 Feb 2020 18:37:42 +0000 From: Christian Brauner To: =?utf-8?q?St=C3=A9phane_Graber?= , "Eric W. Biederman" , Aleksa Sarai , Jann Horn Cc: smbarber@chromium.org, Seth Forshee , Alexander Viro , Alexey Dobriyan , Serge Hallyn , James Morris , Kees Cook , Jonathan Corbet , Phil Estes , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, Christian Brauner Subject: [PATCH v2 09/28] sys:__sys_setuid(): handle fsid mappings Date: Fri, 14 Feb 2020 19:35:35 +0100 Message-Id: <20200214183554.1133805-10-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200214183554.1133805-1-christian.brauner@ubuntu.com> References: <20200214183554.1133805-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Switch setuid() to lookup fsids in the fsid mappings. If no fsid mappings are setup the behavior is unchanged, i.e. fsids are looked up in the id mappings. The kfsid to cleanly handle userns visible filesystem is set as before. We require that a user must have a valid fsid mapping for the target id. This is consistent with how the setid calls work today without fsid mappings. Signed-off-by: Christian Brauner --- /* v2 */ - Christian Brauner : - set kfsid which is used when dealing with proc permission checking --- kernel/sys.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/sys.c b/kernel/sys.c index 864fa78f25a7..a8eefd748327 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -574,11 +574,16 @@ long __sys_setuid(uid_t uid) struct cred *new; int retval; kuid_t kuid; + kuid_t kfsuid; kuid = make_kuid(ns, uid); if (!uid_valid(kuid)) return -EINVAL; + kfsuid = make_kfsuid(ns, uid); + if (!uid_valid(kfsuid)) + return -EINVAL; + new = prepare_creds(); if (!new) return -ENOMEM; @@ -596,7 +601,8 @@ long __sys_setuid(uid_t uid) goto error; } - new->fsuid = new->euid = kuid; + new->kfsuid = new->euid = kuid; + new->fsuid = kfsuid; retval = security_task_fix_setuid(new, old, LSM_SETID_ID); if (retval < 0)