netdev - Re: [PATCH v6 3/7] fs: Add receive_fd() wrapper for __receive

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Message-ID: <202007081646.59E1A664@keescook>
Date:   Wed, 8 Jul 2020 16:48:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     linux-kernel@...r.kernel.org, Sargun Dhillon <sargun@...gun.me>,
        Christian Brauner <christian@...uner.io>,
        Tycho Andersen <tycho@...ho.ws>,
        David Laight <David.Laight@...LAB.COM>,
        Christoph Hellwig <hch@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Aleksa Sarai <cyphar@...har.com>,
        Matt Denton <mpdenton@...gle.com>,
        Jann Horn <jannh@...gle.com>, Chris Palmer <palmer@...gle.com>,
        Robert Sesek <rsesek@...gle.com>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>, Shuah Khan <shuah@...nel.org>,
        netdev@...r.kernel.org, containers@...ts.linux-foundation.org,
        linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v6 3/7] fs: Add receive_fd() wrapper for __receive_fd()

On Tue, Jul 07, 2020 at 01:49:23PM +0200, Christian Brauner wrote:
> On Mon, Jul 06, 2020 at 01:17:16PM -0700, Kees Cook wrote:
> > For both pidfd and seccomp, the __user pointer is not used. Update
> > __receive_fd() to make writing to ufd optional via a NULL check. However,
> > for the receive_fd_user() wrapper, ufd is NULL checked so an -EFAULT
> > can be returned to avoid changing the SCM_RIGHTS interface behavior. Add
> > new wrapper receive_fd() for pidfd and seccomp that does not use the ufd
> > argument. For the new helper, the allocated fd needs to be returned on
> > success. Update the existing callers to handle it.
> > 
> > Reviewed-by: Sargun Dhillon <sargun@...gun.me>
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> 
> Hm, I'm not sure why 2/7 and 3/7 aren't just one patch but ok. :)

I wanted to do a "clean" move from one source to another without any
behavioral changes first.

> Acked-by: Christian Brauner <christian.brauner@...ntu.com>

Thanks!

-- 
Kees Cook