linux-kernel - Re: RFC: named anonymous vmas

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANcMJZBy+yyX=CweduKYw8thN9fxZ2EKZwza9aVwz_cvQa0nxQ@mail.gmail.com>
Date:	Mon, 24 Jun 2013 16:45:12 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	Colin Cross <ccross@...gle.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Alex Elsayed <eternaleye@...il.com>,
	Linux-MM <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: RFC: named anonymous vmas

On Mon, Jun 24, 2013 at 10:26 AM, Colin Cross <ccross@...gle.com> wrote:
> On Mon, Jun 24, 2013 at 4:48 AM, Christoph Hellwig <hch@...radead.org> wrote:
>> On Sat, Jun 22, 2013 at 12:47:29PM -0700, Alex Elsayed wrote:
>>> Couldn't this be done by having a root-only tmpfs, and having a userspace
>>> component that creates per-app directories with restrictive permissions on
>>> startup/app install? Then each app creates files in its own directory, and
>>> can pass the fds around.
>
> If each app gets its own writable directory that's not really
> different than a world writable tmpfs.  It requires something that
> watches for apps to exit for any reason and cleans up their
> directories, and it requires each app to come up with an unused name
> when it wants to create a file, and the kernel can give you both very
> cleanly.

Though, I believe having a daemon that has exclusive access to tmpfs,
and creates, unlinks and passes the fd to the requesting application
would provide a userspace only implementation of the second feature
requirement ("without having a world-writable tmpfs that untrusted
apps could fill with files").  Though I'm not sure what the
proc/<pid>/maps naming would look like on the unlinked file, so it
might not solve the third naming issue.

thanks
-john
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/