From patchwork Tue Feb 18 14:34:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11388663 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 4CEF7924 for ; Tue, 18 Feb 2020 14:36:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3852B24649 for ; Tue, 18 Feb 2020 14:36:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727547AbgBROgE (ORCPT ); Tue, 18 Feb 2020 09:36:04 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:53047 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726750AbgBROfk (ORCPT ); Tue, 18 Feb 2020 09:35:40 -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 1j43y2-0000fF-9Z; Tue, 18 Feb 2020 14:35:18 +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 v3 14/25] open: handle fsid mappings Date: Tue, 18 Feb 2020 15:34:00 +0100 Message-Id: <20200218143411.2389182-15-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200218143411.2389182-1-christian.brauner@ubuntu.com> References: <20200218143411.2389182-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Let chown_common() 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. do_faccessat() just needs to translate from real ids into fsids. Filesystems that share a superblock in all user namespaces they are mounted in will retain their old semantics even with the introduction of fsid mappings. Signed-off-by: Christian Brauner --- /* v2 */ - Christian Brauner : - handle faccessat() too /* v3 */ unchanged --- fs/open.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/open.c b/fs/open.c index 0788b3715731..4e092845728f 100644 --- a/fs/open.c +++ b/fs/open.c @@ -32,6 +32,7 @@ #include #include #include +#include #include "internal.h" @@ -361,8 +362,10 @@ long do_faccessat(int dfd, const char __user *filename, int mode) if (!override_cred) return -ENOMEM; - override_cred->fsuid = override_cred->uid; - override_cred->fsgid = override_cred->gid; + override_cred->kfsuid = override_cred->uid; + override_cred->kfsgid = override_cred->gid; + override_cred->fsuid = kuid_to_kfsuid(override_cred->user_ns, override_cred->uid); + override_cred->fsgid = kgid_to_kfsgid(override_cred->user_ns, override_cred->gid); if (!issecure(SECURE_NO_SETUID_FIXUP)) { /* Clear the capabilities if we switch to a non-root user */ @@ -626,8 +629,13 @@ static int chown_common(const struct path *path, uid_t user, gid_t group) kuid_t uid; kgid_t gid; - uid = make_kuid(current_user_ns(), user); - gid = make_kgid(current_user_ns(), group); + if (is_userns_visible(inode->i_sb->s_iflags)) { + uid = make_kuid(current_user_ns(), user); + gid = make_kgid(current_user_ns(), group); + } else { + uid = make_kfsuid(current_user_ns(), user); + gid = make_kfsgid(current_user_ns(), group); + } retry_deleg: newattrs.ia_valid = ATTR_CTIME;