From: Andy Lutomirski <luto@kernel.org>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Christian Brauner <christian@brauner.io>,
Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Lutomirski <luto@kernel.org>,
David Howells <dhowells@redhat.com>, Jann Horn <jannh@google.com>,
Tycho Andersen <tycho@tycho.ws>,
David Drysdale <drysdale@google.com>,
dev@opencontainers.org,
Linux Containers <containers@lists.linux-foundation.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2 1/3] namei: implement O_BENEATH-style AT_* flags
Date: Tue, 9 Oct 2018 12:25:52 -0700 [thread overview]
Message-ID: <CALCETrUZAYw-g+75WAijS+fmRA_DrTahpv156WrxgYuX3KX2xw@mail.gmail.com> (raw)
In-Reply-To: <20181009065300.11053-3-cyphar@cyphar.com>
On Mon, Oct 8, 2018 at 11:53 PM Aleksa Sarai <cyphar@cyphar.com> wrote:
> * AT_NO_PROCLINK: Disallows ->get_link "symlink" jumping. This is a very
> specific restriction, and it exists because /proc/$pid/fd/...
> "symlinks" allow for access outside nd->root and pose risk to
> container runtimes that don't want to be tricked into accessing a host
> path (but do want to allow no-funny-business symlink resolution).
Can you elaborate on the use case?
If I'm set up a container namespace and walk it for real (through the
outside /proc/PID/root or otherwise starting from an fd that points
into that namespace), and I walk through that namespace's /proc, I'm
going to see the same thing that the processes in the namespace would
see. So what's the issue?
Similarly, if I somehow manage to walk into the outside /proc, then
I've pretty much lost regardless of the links.
--Andy
next prev parent reply other threads:[~2018-10-09 19:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-09 6:52 [PATCH v2 0/3] namei: implement various lookup restriction AT_* flags Aleksa Sarai
2018-10-09 6:52 ` Aleksa Sarai
2018-10-09 6:52 ` [PATCH v2 1/3] namei: implement O_BENEATH-style " Aleksa Sarai
2018-10-09 19:25 ` Andy Lutomirski [this message]
2018-10-10 7:07 ` Aleksa Sarai
2018-10-10 7:28 ` Aleksa Sarai
2018-10-12 1:12 ` Andy Lutomirski
2018-10-27 1:41 ` Ed Maste
2018-10-27 7:17 ` Aleksa Sarai
2018-10-27 7:53 ` Al Viro
2018-10-27 12:11 ` : " Ed Maste
2018-10-27 15:37 ` Aleksa Sarai
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