From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Forshee Subject: [PATCH 18/19] fuse: Restrict allow_other to the superblock's namespace or a descendant Date: Wed, 2 Dec 2015 09:40:18 -0600 Message-ID: <1449070821-73820-19-git-send-email-seth.forshee@canonical.com> References: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1449070821-73820-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: fuse-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: "Eric W. Biederman" , Miklos Szeredi Cc: Serge Hallyn , Seth Forshee , dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, fuse-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Austin S Hemmelgarn , linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Alexander Viro , selinux-+05T5uksL2qpZYMLLGbcSA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-raid.ids Unprivileged users are normally restricted from mounting with the allow_other option by system policy, but this could be bypassed for a mount done with user namespace root permissions. In such cases allow_other should not allow users outside the userns to access the mount as doing so would give the unprivileged user the ability to manipulate processes it would otherwise be unable to manipulate. Restrict allow_other to apply to users in the same userns used at mount or a descendant of that namespace. Signed-off-by: Seth Forshee --- fs/fuse/dir.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index f67f4dd86b36..5b8edb1203b8 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1018,8 +1018,14 @@ int fuse_allow_current_process(struct fuse_conn *fc) { const struct cred *cred; - if (fc->flags & FUSE_ALLOW_OTHER) - return 1; + if (fc->flags & FUSE_ALLOW_OTHER) { + struct user_namespace *ns; + for (ns = current_user_ns(); ns; ns = ns->parent) { + if (ns == fc->user_ns) + return 1; + } + return 0; + } cred = current_cred(); if (uid_eq(cred->euid, fc->user_id) && -- 1.9.1 ------------------------------------------------------------------------------ Go from Idea to Many App Stores Faster with Intel(R) XDK Give your users amazing mobile app experiences with Intel(R) XDK. Use one codebase in this all-in-one HTML5 development environment. Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs. http://pubads.g.doubleclick.net/gampad/clk?id=254741911&iu=/4140