Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756024AbbLDUFp (ORCPT ); Fri, 4 Dec 2015 15:05:45 -0500 Received: from h2.hallyn.com ([78.46.35.8]:45195 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754628AbbLDUFm (ORCPT ); Fri, 4 Dec 2015 15:05:42 -0500 Date: Fri, 4 Dec 2015 14:05:41 -0600 From: "Serge E. Hallyn" To: Seth Forshee Cc: "Eric W. Biederman" , Miklos Szeredi , Alexander Viro , Serge Hallyn , Richard Weinberger , Austin S Hemmelgarn , linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov Subject: Re: [PATCH 18/19] fuse: Restrict allow_other to the superblock's namespace or a descendant Message-ID: <20151204200541.GI3624@mail.hallyn.com> References: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> <1449070821-73820-19-git-send-email-seth.forshee@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1449070821-73820-19-git-send-email-seth.forshee@canonical.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1850 Lines: 52 Quoting Seth Forshee (seth.forshee@canonical.com): > 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; > + } use current_in_userns() ? > + return 0; > + } > > cred = current_cred(); > if (uid_eq(cred->euid, fc->user_id) && > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/