Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932927AbbLBPnJ (ORCPT ); Wed, 2 Dec 2015 10:43:09 -0500 Received: from mail-ig0-f174.google.com ([209.85.213.174]:37907 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757463AbbLBPmi (ORCPT ); Wed, 2 Dec 2015 10:42:38 -0500 From: Seth Forshee To: "Eric W. Biederman" , Miklos Szeredi Cc: 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, 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> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> References: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1439 Lines: 43 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 -- 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/