From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jamie Lokier <jamie@shareable.org>,
Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org, keescook@chromium.org,
john.johansen@canonical.com, serge.hallyn@canonical.com,
coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com,
djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org,
jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com,
penberg@cs.helsinki.fi, mingo@elte.hu, akpm@linux-foundation.org,
khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com,
oleg@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com,
gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, olofj@chromium.org,
mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH 4/4] Allow unprivileged chroot when safe
Date: Mon, 16 Jan 2012 20:26:04 +0000 [thread overview]
Message-ID: <20120116202604.GO23916@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CALCETrU62cq43hd7Wray0eZQfbQ9+hkuuo9AzCFgrL_2h_v7qw@mail.gmail.com>
On Mon, Jan 16, 2012 at 12:15:09PM -0800, Andy Lutomirski wrote:
> The first approach I tried was (from memory -- may not compile at all
> on any version) fs->root.mnt != fs->root.mnt->mnt_parent. That didn't
> work. The issue is that on dracut-based distros, AFAICT, the root (in
> the sense of the root of the tree of struct vfsmounts) is rootfs. The
> apparent root (the filesystem containing /, /usr, etc) is mounted on
> top of (rootfs)/. Dracut then does something with the effect of
> chroot("/"). So you end up with the vfsmount that contains "/" not
> being the actual root vfsmount. But there's nothing hidden by the
> chroot -- even if fs->root.mnt pointed at rootfs, "/" would still
> follow the mountpoint into the actual filesystem.
That has nothing whatsoever to do with dracut. _Everything_ ends up
that way; IOW, everything including init(8) runs chrooted into the
final userland root. On any normal distro. Your test is complete BS - e.g.
mount /dev/crap /mnt/blah
mount /dev/garbage /mnt/blah
chroot /mnt/blah
will *NOT* be chrooted per your definition.
next prev parent reply other threads:[~2012-01-16 20:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 0:37 [PATCH v2 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 1/4] Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs Andy Lutomirski
2012-01-16 17:33 ` Oleg Nesterov
2012-01-16 20:15 ` Andy Lutomirski
2012-01-16 20:15 ` Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 2/4] Fix apparmor for PR_{GET,SET}_NO_NEW_PRIVS Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 3/4] Allow unprivileged CLONE_NEWUTS and CLONE_NEWIPC with no_new_privs Andy Lutomirski
2012-01-16 0:37 ` [PATCH 4/4] Allow unprivileged chroot when safe Andy Lutomirski
2012-01-16 0:45 ` Linus Torvalds
2012-01-16 0:45 ` Linus Torvalds
2012-01-16 1:08 ` Andy Lutomirski
2012-01-16 1:08 ` Andy Lutomirski
2012-01-16 19:26 ` Colin Walters
2012-01-16 19:26 ` Colin Walters
2012-01-16 20:18 ` Andy Lutomirski
2012-01-16 20:18 ` Andy Lutomirski
2012-01-17 10:14 ` Jamie Lokier
2012-01-17 10:14 ` Jamie Lokier
2012-01-16 20:06 ` Al Viro
2012-01-16 20:15 ` Andy Lutomirski
2012-01-16 20:26 ` Al Viro [this message]
2012-01-17 16:23 ` Oleg Nesterov
2012-01-17 16:31 ` Andy Lutomirski
2012-01-16 1:04 ` [PATCH v2 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot Andy Lutomirski
2012-01-16 1:04 ` Andy Lutomirski
2012-01-16 20:49 ` Colin Walters
2012-01-16 20:49 ` Colin Walters
2012-01-16 21:25 ` Andy Lutomirski
2012-01-16 21:25 ` Andy Lutomirski
2012-01-16 21:47 ` Colin Walters
2012-01-16 21:47 ` Colin Walters
2012-01-16 21:57 ` Andy Lutomirski
2012-01-16 21:57 ` Andy Lutomirski
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