From: Christian Brauner <brauner@kernel.org>
To: Michal Clapinski <mclapinski@google.com>
Cc: Jeff Layton <jlayton@kernel.org>,
Chuck Lever <chuck.lever@oracle.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Shuah Khan <shuah@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jeff Xu <jeffxu@google.com>, Aleksa Sarai <cyphar@cyphar.com>,
Daniel Verkamp <dverkamp@chromium.org>,
Kees Cook <keescook@chromium.org>,
Marc Dionne <marc.dionne@auristor.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 1/2] fcntl: add fcntl(F_CHECK_ORIGINAL_MEMFD)
Date: Fri, 1 Sep 2023 14:56:14 +0200 [thread overview]
Message-ID: <20230901-lockt-erbfolge-e1f9a26f0d63@brauner> (raw)
In-Reply-To: <20230831203647.558079-2-mclapinski@google.com>
On Thu, Aug 31, 2023 at 10:36:46PM +0200, Michal Clapinski wrote:
> Add a way to check if an fd points to the memfd's original open fd
> (the one created by memfd_create).
> Useful because only the original open fd can be both writable and
> executable.
>
> Signed-off-by: Michal Clapinski <mclapinski@google.com>
> ---
> fs/fcntl.c | 3 +++
> include/uapi/linux/fcntl.h | 9 +++++++++
> 2 files changed, 12 insertions(+)
>
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index e871009f6c88..301527e07a4d 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -419,6 +419,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
> case F_SET_RW_HINT:
> err = fcntl_rw_hint(filp, cmd, arg);
> break;
> + case F_CHECK_ORIGINAL_MEMFD:
> + err = !(filp->f_mode & FMODE_WRITER);
> + break;
Honestly, make this an ioctl on memfds. This is so specific that it
really doesn't belong into fcntl().
next prev parent reply other threads:[~2023-09-01 12:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 20:36 [PATCH 0/2] fcntl: add fcntl(F_CHECK_ORIGINAL_MEMFD) Michal Clapinski
2023-08-31 20:36 ` [PATCH 1/2] " Michal Clapinski
2023-09-01 12:56 ` Christian Brauner [this message]
2023-09-01 14:50 ` Michał Cłapiński
2023-09-01 18:34 ` Kees Cook
2023-09-04 7:29 ` Christian Brauner
2023-09-04 17:57 ` Michał Cłapiński
2023-09-05 8:37 ` Christian Brauner
2023-08-31 20:36 ` [PATCH 2/2] selftests: test fcntl(F_CHECK_ORIGINAL_MEMFD) Michal Clapinski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230901-lockt-erbfolge-e1f9a26f0d63@brauner \
--to=brauner@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=chuck.lever@oracle.com \
--cc=cyphar@cyphar.com \
--cc=dverkamp@chromium.org \
--cc=jeffxu@google.com \
--cc=jlayton@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=marc.dionne@auristor.com \
--cc=mclapinski@google.com \
--cc=shuah@kernel.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).