netdev - Re: [Patch bpf-next v3 03/10] af_unix: implement ->psock_update_sk

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Message-ID: <87o8doui7s.fsf@cloudflare.com>
Date:   Thu, 06 May 2021 15:04:07 +0200
From:   Jakub Sitnicki <jakub@...udflare.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        jiang.wang@...edance.com, duanxiongchun@...edance.com,
        wangdongdong.6@...edance.com, Cong Wang <cong.wang@...edance.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [Patch bpf-next v3 03/10] af_unix: implement
 ->psock_update_sk_prot()

On Mon, Apr 26, 2021 at 04:49 AM CEST, Cong Wang wrote:
> From: Cong Wang <cong.wang@...edance.com>
>
> unix_proto is special, it is very different from INET proto,
> which even does not have a ->close(). We have to add a dummy
> one to satisfy sockmap.
>
> And now we can implement unix_bpf_update_proto() to update
> sk_prot.
>
> Cc: John Fastabend <john.fastabend@...il.com>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: Jakub Sitnicki <jakub@...udflare.com>
> Cc: Lorenz Bauer <lmb@...udflare.com>
> Signed-off-by: Cong Wang <cong.wang@...edance.com>
> ---

[...]

> diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
> new file mode 100644
> index 000000000000..b1582a659427
> --- /dev/null
> +++ b/net/unix/unix_bpf.c
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2021 Cong Wang <cong.wang@...edance.com> */
> +
> +#include <linux/skmsg.h>
> +#include <linux/bpf.h>
> +#include <net/sock.h>
> +#include <net/af_unix.h>
> +
> +static struct proto *unix_prot_saved __read_mostly;
> +static DEFINE_SPINLOCK(unix_prot_lock);
> +static struct proto unix_bpf_prot;
> +
> +static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
> +{
> +	*prot        = *base;
> +	prot->close  = sock_map_close;
> +}

I think we also need unhash so that socket gets removed from sockmap
on disconnect, that is connect(fd, {sa_family=AF_UNSPEC, ...}, ...).