From: Joel Fernandes <joel@joelfernandes.org>
To: Michael Tirado <mtirado418@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Jann Horn <jannh@google.com>, LKML <linux-kernel@vger.kernel.org>,
jreck@google.com, john.stultz@linaro.org, tkjos@google.com,
gregkh@linuxfoundation.org, hch@infradead.org,
viro@zeniv.linux.org.uk,
Andrew Morton <akpm@linux-foundation.org>,
dancol@google.com, bfields@fieldses.org, jlayton@kernel.org,
khalid.aziz@oracle.com, Lei.Yang@windriver.com,
linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, marcandre.lureau@redhat.com,
mike.kravetz@oracle.com, minchan@kernel.org, shuah@kernel.org,
valdis.kletnieks@vt.edu, hughd@google.com,
linux-api@vger.kernel.org
Subject: Re: [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd
Date: Fri, 9 Nov 2018 17:49:13 -0800 [thread overview]
Message-ID: <20181110014913.GA202500@google.com> (raw)
In-Reply-To: <CAMkWEXOLJ=ymbVjQfA2MD8XA7Y9Lu3ByJYUY-JvpnYKJ5gkY1w@mail.gmail.com>
On Fri, Nov 09, 2018 at 08:02:14PM +0000, Michael Tirado wrote:
[...]
> > > That aside: I wonder whether a better API would be something that
> > > allows you to create a new readonly file descriptor, instead of
> > > fiddling with the writability of an existing fd.
> >
> > Every now and then I try to write a patch to prevent using proc to reopen
> > a file with greater permission than the original open.
> >
> > I like your idea to have a clean way to reopen a a memfd with reduced
> > permissions. But I would make it a syscall instead and maybe make it only
> > work for memfd at first. And the proc issue would need to be fixed, too.
>
> IMO the best solution would handle the issue at memfd creation time by
> removing the race condition.
I agree, this is another idea I'm exploring. We could add a new .open
callback to shmem_file_operations and check for seals there.
thanks,
- Joel
next prev parent reply other threads:[~2018-11-10 1:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-08 4:15 [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd Joel Fernandes (Google)
2018-11-08 4:15 ` [PATCH v3 resend 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal Joel Fernandes (Google)
2018-11-09 8:49 ` [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd Joel Fernandes
2018-11-09 20:36 ` Andrew Morton
2018-11-10 3:54 ` Joel Fernandes
2018-11-09 21:06 ` Jann Horn
2018-11-09 21:19 ` Jann Horn
2018-11-10 3:20 ` Joel Fernandes
2018-11-10 6:05 ` Andy Lutomirski
2018-11-10 18:24 ` Joel Fernandes
2018-11-10 18:45 ` Daniel Colascione
2018-11-10 19:11 ` Daniel Colascione
2018-11-10 19:55 ` Andy Lutomirski
2018-11-10 22:09 ` Joel Fernandes
2018-11-10 22:18 ` Andy Lutomirski
2018-11-11 2:38 ` Joel Fernandes
2018-11-11 3:40 ` Andy Lutomirski
2018-11-11 4:01 ` Joel Fernandes
2018-11-11 8:09 ` Joel Fernandes
2018-11-11 8:30 ` Daniel Colascione
2018-11-11 15:14 ` Andy Lutomirski
2018-11-11 17:36 ` Joel Fernandes
[not found] ` <CAKOZuethC7+YrRyyGciUCfhSSa9cCcAFJ8g_qEw9uh3TBbyOcg@mail.gmail.com>
2018-11-10 17:10 ` Joel Fernandes
2018-11-09 21:40 ` Andy Lutomirski
2018-11-09 20:02 ` Michael Tirado
2018-11-10 1:49 ` Joel Fernandes [this message]
2018-11-09 22:20 ` Daniel Colascione
2018-11-09 22:37 ` Andy Lutomirski
2018-11-09 22:42 ` Daniel Colascione
2018-11-09 23:14 ` Andy Lutomirski
2018-11-10 1:36 ` Joel Fernandes
2018-11-09 23:46 ` Joel Fernandes
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