From: Peter Xu <peterx@redhat.com>
To: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
David Hildenbrand <david@redhat.com>,
Lokesh Gidra <lokeshgidra@google.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
linux-kernel@vger.kernel.org,
Robert O'Callahan <roc@ocallahan.org>
Subject: Re: [RFC PATCH RESEND] userfaultfd: open userfaultfds with O_RDONLY
Date: Tue, 12 Jul 2022 10:22:25 -0400 [thread overview]
Message-ID: <Ys2DobolHlrXP4/M@xz-m1.local> (raw)
In-Reply-To: <20220708093451.472870-1-omosnace@redhat.com>
On Fri, Jul 08, 2022 at 11:34:51AM +0200, Ondrej Mosnacek wrote:
> Since userfaultfd doesn't implement a write operation, it is more
> appropriate to open it read-only.
>
> When userfaultfds are opened read-write like it is now, and such fd is
> passed from one process to another, SELinux will check both read and
> write permissions for the target process, even though it can't actually
> do any write operation on the fd later.
>
> Inspired by the following bug report, which has hit the SELinux scenario
> described above:
> https://bugzilla.redhat.com/show_bug.cgi?id=1974559
>
> Reported-by: Robert O'Callahan <roc@ocallahan.org>
> Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization")
> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2022-07-12 14:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-08 9:34 [RFC PATCH RESEND] userfaultfd: open userfaultfds with O_RDONLY Ondrej Mosnacek
2022-07-12 14:22 ` Peter Xu [this message]
2022-07-12 21:16 ` Paul Moore
2022-08-16 22:12 ` Paul Moore
2022-08-19 18:50 ` Paul Moore
2022-08-26 8:43 ` Christian Brauner
2022-08-30 20:10 ` Paul Moore
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