netdev - Re: [PATCH 2/3] net/unix: hook unix

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Message-ID: <CAHC9VhSv6tacFb+nEs1cCUOj52Vu+wXD6ZPZ1r1W4pYXo0VJMQ@mail.gmail.com>
Date:   Tue, 24 Apr 2018 13:55:31 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     David Herrmann <dh.herrmann@...il.com>
Cc:     linux-kernel@...r.kernel.org, James Morris <jmorris@...ei.org>,
        teg@...m.no, Stephen Smalley <sds@...ho.nsa.gov>,
        selinux@...ho.nsa.gov, linux-security-module@...r.kernel.org,
        Eric Paris <eparis@...isplace.org>, serge@...lyn.com,
        davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH 2/3] net/unix: hook unix_socketpair() into LSM

On Mon, Apr 23, 2018 at 9:30 AM, David Herrmann <dh.herrmann@...il.com> wrote:
> Use the newly created LSM-hook for unix_socketpair(). The default hook
> return-value is 0, so behavior stays the same unless LSMs start using
> this hook.
>
> Signed-off-by: David Herrmann <dh.herrmann@...il.com>
> ---
>  net/unix/af_unix.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 68bb70a62afe..bc9705ace9b1 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1371,6 +1371,11 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>  static int unix_socketpair(struct socket *socka, struct socket *sockb)
>  {
>         struct sock *ska = socka->sk, *skb = sockb->sk;
> +       int err;
> +
> +       err = security_unix_stream_socketpair(ska, skb);
> +       if (err)
> +               return err;

I recognize that AF_UNIX is really the only protocol that supports
socketpair(2) at the moment, but I like to avoid protocol specific LSM
hooks whenever possible.  Unless someone can think of a good
objection, I would prefer to see the hook placed in __sys_socketpair()
instead (and obviously drop the "unix_stream" portion from the hook
name).

>         /* Join our sockets back to back */
>         sock_hold(ska);
> --
> 2.17.0

-- 
paul moore
www.paul-moore.com