From patchwork Tue Feb 11 16:57:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11376031 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 0D08E14E3 for ; Tue, 11 Feb 2020 17:02:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E82A920848 for ; Tue, 11 Feb 2020 17:02:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728238AbgBKRCs (ORCPT ); Tue, 11 Feb 2020 12:02:48 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:53686 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727964AbgBKRCs (ORCPT ); Tue, 11 Feb 2020 12:02:48 -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 1j1Ysg-00014T-Iy; Tue, 11 Feb 2020 16:59:26 +0000 From: Christian Brauner To: =?utf-8?q?St=C3=A9phane_Graber?= , "Eric W. Biederman" , Aleksa Sarai , Jann Horn Cc: smbarber@chromium.org, Alexander Viro , Alexey Dobriyan , Serge Hallyn , James Morris , Kees Cook , Jonathan Corbet , 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 21/24] sys:__sys_setregid(): handle fsid mappings Date: Tue, 11 Feb 2020 17:57:50 +0100 Message-Id: <20200211165753.356508-22-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200211165753.356508-1-christian.brauner@ubuntu.com> References: <20200211165753.356508-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Switch setregid() 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. During setregid() the kfsgid is set to the kegid corresponding the egid that is requested by userspace. If the requested egid is -1 the kfsgid is reset to the current kegid. For the latter case this means we need to lookup the corresponding userspace egid corresponding to the current kegid in the id mappings and translate this egid into the corresponding kfsgid in the fsid mappings. Signed-off-by: Christian Brauner --- kernel/sys.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index ef1104c9df56..41551c01c3eb 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -354,15 +354,18 @@ long __sys_setregid(gid_t rgid, gid_t egid) const struct cred *old; struct cred *new; int retval; - kgid_t krgid, kegid; + kgid_t krgid, kegid, kfsgid; krgid = make_kgid(ns, rgid); kegid = make_kgid(ns, egid); + kfsgid = make_kfsgid(ns, egid); if ((rgid != (gid_t) -1) && !gid_valid(krgid)) return -EINVAL; if ((egid != (gid_t) -1) && !gid_valid(kegid)) return -EINVAL; + if ((egid != (gid_t) -1) && !gid_valid(kfsgid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -386,12 +389,15 @@ long __sys_setregid(gid_t rgid, gid_t egid) new->egid = kegid; else goto error; + } else { + gid_t fsgid = from_kgid_munged(new->user_ns, new->egid); + kfsgid = make_kfsgid(ns, fsgid); } if (rgid != (gid_t) -1 || (egid != (gid_t) -1 && !gid_eq(kegid, old->gid))) new->sgid = new->egid; - new->fsgid = new->egid; + new->fsgid = kfsgid; return commit_creds(new);