From patchwork Tue Feb 11 16:57:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11376027 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 550D21580 for ; Tue, 11 Feb 2020 17:02:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3DBF02082F for ; Tue, 11 Feb 2020 17:02:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728228AbgBKRCX (ORCPT ); Tue, 11 Feb 2020 12:02:23 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:53662 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727895AbgBKRCX (ORCPT ); Tue, 11 Feb 2020 12:02:23 -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 1j1Ysi-00014T-SQ; Tue, 11 Feb 2020 16:59:28 +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 23/24] sys:__sys_setresgid(): handle fsid mappings Date: Tue, 11 Feb 2020 17:57:52 +0100 Message-Id: <20200211165753.356508-24-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 setresgid() 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 setresgid() 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 | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 3b98ce84607d..674d0ba4887c 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -750,11 +750,12 @@ long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid) const struct cred *old; struct cred *new; int retval; - kgid_t krgid, kegid, ksgid; + kgid_t krgid, kegid, ksgid, kfsgid; krgid = make_kgid(ns, rgid); kegid = make_kgid(ns, egid); ksgid = make_kgid(ns, sgid); + kfsgid = make_kfsgid(ns, egid); if ((rgid != (gid_t) -1) && !gid_valid(krgid)) return -EINVAL; @@ -762,6 +763,8 @@ long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid) return -EINVAL; if ((sgid != (gid_t) -1) && !gid_valid(ksgid)) return -EINVAL; + if ((egid != (gid_t) -1) && !gid_valid(kfsgid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -783,11 +786,15 @@ long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid) if (rgid != (gid_t) -1) new->gid = krgid; - if (egid != (gid_t) -1) + if (egid != (gid_t) -1) { new->egid = kegid; + } else { + gid_t fsgid = from_kgid_munged(new->user_ns, new->egid); + kfsgid = make_kfsgid(ns, fsgid); + } if (sgid != (gid_t) -1) new->sgid = ksgid; - new->fsgid = new->egid; + new->fsgid = kfsgid; return commit_creds(new);