netdev - Re: [PATCH v2 bpf-next 0/7] Add __sk_buff->sk, bpf_tcp_sock, BPF_FUNC_tcp_sock and BPF_FUNC_sk

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Date:   Sun, 10 Feb 2019 19:55:43 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     netdev@...r.kernel.org, Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>, kernel-team@...com,
        Lawrence Brakmo <brakmo@...com>
Subject: Re: [PATCH v2 bpf-next 0/7] Add __sk_buff->sk, bpf_tcp_sock,
 BPF_FUNC_tcp_sock and BPF_FUNC_sk_fullsock

On Sat, Feb 09, 2019 at 11:22:20PM -0800, Martin KaFai Lau wrote:
> This series adds __sk_buff->sk, "struct bpf_tcp_sock",
> BPF_FUNC_sk_fullsock and BPF_FUNC_tcp_sock.  Together, they provide
> a common way to expose the members of "struct tcp_sock" and
> "struct bpf_sock" for the bpf_prog to access.
> 
> The patch series first adds a bpf_sock pointer to __sk_buff
> and a new helper BPF_FUNC_sk_fullsock.
> 
> It then adds BPF_FUNC_tcp_sock to get a bpf_tcp_sock
> pointer from a bpf_sock pointer.
> 
> The current use case is to allow a cg_skb_bpf_prog to provide
> per cgroup traffic policing/shaping.
> 
> Please see individual patch for details.
> 
> v2:
> - Patch 1 depends on
>   commit d623876646be ("bpf: Fix narrow load on a bpf_sock returned from sk_lookup()")
>   in the bpf branch.
> - Add sk_to_full_sk() to bpf_sk_fullsock() and bpf_tcp_sock()
>   such that there is a way to access the listener's sk and tcp_sk
>   when __sk_buff->sk is a request_sock.
>   The comments in the uapi bpf.h is updated accordingly.
> - bpf_ctx_range_till() is used in bpf_sock_common_is_valid_access()
>   in patch 1.  Saved a few lines.
> - Patch 2 is new in v2 and it adds "state", "dst_ip4", "dst_ip6" and
>   "dst_port" to the bpf_sock.  Narrow load is allowed on them.
>   The "state" (i.e. sk_state) has already been used in
>   INET_DIAG (e.g. ss -t) and getsockopt(TCP_INFO).
> - While at it in the new patch 2, also allow narrow load on some
>   existing fields of the bpf_sock, which are "family", "type", "protocol"
>   and "src_port".  Only allow loading from first byte for now.
>   i.e. does not allow narrow load starting from the 2nd byte.
> - Add some narrow load tests to the test_verifier's sock.c

Daniel,
I believe this new revision addresses your concerns exactly as we discussed.
So I pushed it to bpf-next.
please double check that it's what you expected.
We can always revert.
Thanks everyone!