From: Seth Forshee <seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>, Miklos Szeredi <miklos-sUDqSbJrdHQHWmgEVkV9KA@public.gmane.org> Cc: Serge Hallyn <serge.hallyn-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>, Seth Forshee <seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>, 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 <ahferroin7-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Alexander Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, selinux-+05T5uksL2qpZYMLLGbcSA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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 [thread overview] Message-ID: <1449070821-73820-19-git-send-email-seth.forshee@canonical.com> (raw) In-Reply-To: <1449070821-73820-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 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 <seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> --- 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
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From: Seth Forshee <seth.forshee@canonical.com> To: "Eric W. Biederman" <ebiederm@xmission.com>, Miklos Szeredi <miklos@szeredi.hu> Cc: Alexander Viro <viro@zeniv.linux.org.uk>, Serge Hallyn <serge.hallyn@canonical.com>, Richard Weinberger <richard.weinberger@gmail.com>, Austin S Hemmelgarn <ahferroin7@gmail.com>, 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 <seth.forshee@canonical.com> 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 [thread overview] Message-ID: <1449070821-73820-19-git-send-email-seth.forshee@canonical.com> (raw) In-Reply-To: <1449070821-73820-1-git-send-email-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 <seth.forshee@canonical.com> --- 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
next prev parent reply other threads:[~2015-12-02 15:40 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-12-02 15:40 [PATCH 00/19] Support fuse mounts in user namespaces Seth Forshee 2015-12-02 15:40 ` [PATCH 02/19] block_dev: Check permissions towards block device inode when mounting Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 16:28 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 03/19] fs: Treat foreign mounts as nosuid Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 16:55 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 04/19] selinux: Add support for unprivileged mounts from user namespaces Seth Forshee 2015-12-02 15:40 ` [PATCH 05/19] userns: Replace in_userns with current_in_userns Seth Forshee 2015-12-04 17:01 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 08/19] cred: Reject inodes with invalid ids in set_create_file_as() Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 16:49 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 12/19] fs: Don't remove suid for CAP_FSETID in s_user_ns Seth Forshee 2015-12-04 19:02 ` Serge E. Hallyn [not found] ` <1449070821-73820-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 2015-12-02 15:40 ` [PATCH 01/19] block_dev: Support checking inode permissions in lookup_bdev() Seth Forshee 2015-12-02 15:40 ` Seth Forshee [not found] ` <1449070821-73820-2-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 2015-12-04 16:26 ` Serge E. Hallyn 2015-12-04 16:26 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 06/19] Smack: Handle labels consistently in untrusted mounts Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-02 15:40 ` [PATCH 07/19] fs: Check for invalid i_uid in may_follow_link() Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 16:42 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 09/19] fs: Refuse uid/gid changes which don't map into s_user_ns Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 17:27 ` Serge E. Hallyn 2015-12-04 17:46 ` Seth Forshee 2015-12-04 19:42 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 10/19] fs: Update posix_acl support to handle user namespace mounts Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 18:50 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 11/19] fs: Ensure the mounter of a filesystem is privileged towards its inodes Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 19:00 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 13/19] fs: Allow superblock owner to access do_remount_sb() Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 19:02 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in s_user_ns Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 19:11 ` Serge E. Hallyn 2015-12-04 20:05 ` Theodore Ts'o 2015-12-04 20:07 ` Serge E. Hallyn [not found] ` <20151204200736.GJ3624-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org> 2015-12-04 20:45 ` Seth Forshee 2015-12-04 20:45 ` Seth Forshee 2015-12-04 23:11 ` Theodore Ts'o 2015-12-04 23:43 ` Serge E. Hallyn 2015-12-05 6:15 ` Seth Forshee 2015-12-05 0:00 ` Andreas Dilger 2015-12-02 15:40 ` [PATCH 17/19] fuse: Support fuse filesystems outside of init_user_ns Seth Forshee 2015-12-02 15:40 ` Seth Forshee 2015-12-04 15:38 ` Seth Forshee 2015-12-04 20:03 ` Serge E. Hallyn 2015-12-04 20:41 ` Seth Forshee 2015-12-04 21:57 ` Serge E. Hallyn 2015-12-02 15:40 ` Seth Forshee [this message] 2015-12-02 15:40 ` [PATCH 18/19] fuse: Restrict allow_other to the superblock's namespace or a descendant Seth Forshee 2015-12-04 20:05 ` Serge E. Hallyn 2015-12-04 20:43 ` Seth Forshee 2015-12-04 21:57 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 15/19] capabilities: Allow privileged user in s_user_ns to set file caps Seth Forshee 2015-12-04 19:42 ` Serge E. Hallyn 2015-12-04 20:36 ` Seth Forshee 2015-12-04 22:05 ` Serge E. Hallyn 2015-12-02 15:40 ` [PATCH 16/19] fuse: Add support for pid namespaces Seth Forshee 2015-12-02 15:40 ` [PATCH 19/19] fuse: Allow user namespace mounts Seth Forshee
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