From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out01.mta.xmission.com ([166.70.13.231]:48370 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935144AbeEWX0r (ORCPT ); Wed, 23 May 2018 19:26:47 -0400 From: "Eric W. Biederman" To: Linux Containers Cc: linux-fsdevel@vger.kernel.org, Seth Forshee , "Serge E. Hallyn" , Christian Brauner , linux-kernel@vger.kernel.org, "Eric W. Biederman" Date: Wed, 23 May 2018 18:25:36 -0500 Message-Id: <20180523232538.4880-4-ebiederm@xmission.com> In-Reply-To: <87o9h6554f.fsf@xmission.com> References: <87o9h6554f.fsf@xmission.com> Subject: [REVIEW][PATCH 4/6] fs: Allow superblock owner to access do_remount_sb() Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Superblock level remounts are currently restricted to global CAP_SYS_ADMIN, as is the path for changing the root mount to read only on umount. Loosen both of these permission checks to also allow CAP_SYS_ADMIN in any namespace which is privileged towards the userns which originally mounted the filesystem. Signed-off-by: Seth Forshee Acked-by: "Eric W. Biederman" Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman --- fs/namespace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 5f75969adff1..8ddd14806799 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1590,7 +1590,7 @@ static int do_umount(struct mount *mnt, int flags) * Special case for "unmounting" root ... * we just try to remount it readonly. */ - if (!capable(CAP_SYS_ADMIN)) + if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) return -EPERM; down_write(&sb->s_umount); if (!sb_rdonly(sb)) @@ -2333,7 +2333,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, down_write(&sb->s_umount); if (ms_flags & MS_BIND) err = change_mount_flags(path->mnt, ms_flags); - else if (!capable(CAP_SYS_ADMIN)) + else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) err = -EPERM; else err = do_remount_sb(sb, sb_flags, data, 0); -- 2.14.1