netdev - RE: [PATCH bpf-next 01/14] net: Change sock_setsockopt from taking sock ptr to sk ptr

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Message-ID: <a9a3e00db4764ffcaf3324046d736b76@AcuMS.aculab.com>
Date:   Wed, 27 Jul 2022 08:11:26 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Martin KaFai Lau' <kafai@...com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "kernel-team@...com" <kernel-team@...com>,
        Paolo Abeni <pabeni@...hat.com>
Subject: RE: [PATCH bpf-next 01/14] net: Change sock_setsockopt from taking
 sock ptr to sk ptr

From: Martin KaFai Lau
> Sent: 27 July 2022 07:09
> 
> A latter patch refactors bpf_setsockopt(SOL_SOCKET) with the
> sock_setsockopt() to avoid code duplication and code
> drift between the two duplicates.
> 
> The current sock_setsockopt() takes sock ptr as the argument.
> The very first thing of this function is to get back the sk ptr
> by 'sk = sock->sk'.
> 
> bpf_setsockopt() could be called when the sk does not have
> a userspace owner.  Meaning sk->sk_socket is NULL.  For example,
> when a passive tcp connection has just been established.  Thus,
> it cannot use the sock_setsockopt(sk->sk_socket) or else it will
> pass a NULL sock ptr.

I'm intrigued, I've some code that uses sock_create_kern() to create
sockets without a userspace owner - I'd have though bpf is doing
much the same.

I end up doing:
        if (level == SOL_SOCKET)
                err = sock_setsockopt(sock, level, optname, koptval, optlen);
        else
                err = sock->ops->setsockopt(sock, level, optname, koptval,
                                            optlen);
to set options.
(This code used to use kern_setsockopt() - but that got removed.)

I'd have though bpf would need similar code??

	David

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