From: Andy Lutomirski <luto@amacapital.net>
To: Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>,
linux-kernel@vger.kernel.org
Subject: Re: How is pivot_root intended to be used?
Date: Tue, 02 Sep 2014 12:53:14 -0700 [thread overview]
Message-ID: <5406202A.30401@amacapital.net> (raw)
In-Reply-To: <fc0cb509956.5404e2cc@langara.bc.ca>
On 09/01/2014 02:19 PM, Steven Stewart-Gallus wrote:
> Hello,
>
> I am not confused about how I can currently use pivot_root for
> containers on my kernel (version 3.13). Currently a sequence like:
>
> if (-1 == syscall(__NR_pivot_root, ".", ".")) {
> perror("pivot_root");
> return EXIT_FAILURE;
> }
>
> if (-1 == umount2(".", MNT_DETACH)) {
> perror("umount");
> return EXIT_FAILURE;
Given the comment, you don't know what '.' refers to in the umount2 call
above. In fact, I think you're actually detaching the wrong thing,
leaving possible security issues.
See:
https://github.com/sandstorm-io/sandstorm/blob/master/src/sandstorm/supervisor-main.c%2B%2B#L922
for a program that does this more carefully.
--Andy
next prev parent reply other threads:[~2014-09-02 19:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-01 21:19 How is pivot_root intended to be used? Steven Stewart-Gallus
2014-09-02 19:53 ` Andy Lutomirski [this message]
2014-09-04 7:35 ` Steven Stewart-Gallus
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