From patchwork Fri Feb 14 18:35:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11383051 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 321D613A4 for ; Fri, 14 Feb 2020 18:38:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1B94D222C2 for ; Fri, 14 Feb 2020 18:38:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390176AbgBNSiq (ORCPT ); Fri, 14 Feb 2020 13:38:46 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:33676 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730585AbgBNSiC (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 1j2fqU-0000uO-Ht; Fri, 14 Feb 2020 18:37:46 +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 12/28] sys:__sys_setregid(): handle fsid mappings Date: Fri, 14 Feb 2020 19:35:38 +0100 Message-Id: <20200214183554.1133805-13-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 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. 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 | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 4697e010bbd7..22eea030d9e7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -354,7 +354,7 @@ 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); @@ -386,12 +386,20 @@ long __sys_setregid(gid_t rgid, gid_t egid) new->egid = kegid; else goto error; + kfsgid = make_kfsgid(ns, egid); + } else { + kfsgid = kgid_to_kfsgid(new->user_ns, new->egid); + } + if (!gid_valid(kfsgid)) { + retval = -EINVAL; + goto error; } if (rgid != (gid_t) -1 || (egid != (gid_t) -1 && !gid_eq(kegid, old->gid))) new->sgid = new->egid; - new->fsgid = new->egid; + new->kfsgid = new->egid; + new->fsgid = kfsgid; return commit_creds(new);