From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Lawrence Brakmo <brakmo@fb.com>
Cc: netdev <netdev@vger.kernel.org>, Kernel Team <kernel-team@fb.com>,
Blake Matheny <bmatheny@fb.com>, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: [PATCH bpf-next v6 05/11] bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock
Date: Fri, 19 Jan 2018 19:52:22 -0800 [thread overview]
Message-ID: <20180120035220.rg55abc6gk2alere@ast-mbp> (raw)
In-Reply-To: <20180120014548.2941040-6-brakmo@fb.com>
On Fri, Jan 19, 2018 at 05:45:42PM -0800, Lawrence Brakmo wrote:
> Adds field bpf_sock_ops_cb_flags to tcp_sock and bpf_sock_ops. Its primary
> use is to determine if there should be calls to sock_ops bpf program at
> various points in the TCP code. The field is initialized to zero,
> disabling the calls. A sock_ops BPF program can set it, per connection and
> as necessary, when the connection is established.
>
> It also adds support for reading and writting the field within a
> sock_ops BPF program. Reading is done by accessing the field directly.
> However, writing is done through the helper function
> bpf_sock_ops_cb_flags_set, in order to return an error if a BPF program
> is trying to set a callback that is not supported in the current kernel
> (i.e. running an older kernel). The helper function returns 0 if it was
> able to set all of the bits set in the argument, a positive number
> containing the bits that could not be set, or -EINVAL if the socket is
> not a full TCP socket.
...
> +/* Sock_ops bpf program related variables */
> +#ifdef CONFIG_BPF
> + u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs
> + * values defined in uapi/linux/tcp.h
I guess we can extend u8 into u16 or more if necessary in the future.
> + * int bpf_sock_ops_cb_flags_set(bpf_sock_ops, flags)
> + * Set callback flags for sock_ops
> + * @bpf_sock_ops: pointer to bpf_sock_ops_kern struct
> + * @flags: flags value
> + * Return: 0 for no error
> + * -EINVAL if there is no full tcp socket
> + * bits in flags that are not supported by current kernel
...
> +BPF_CALL_2(bpf_sock_ops_cb_flags_set, struct bpf_sock_ops_kern *, bpf_sock,
> + int, argval)
> +{
> + struct sock *sk = bpf_sock->sk;
> + int val = argval & BPF_SOCK_OPS_ALL_CB_FLAGS;
> +
> + if (!sk_fullsock(sk))
> + return -EINVAL;
> +
> +#ifdef CONFIG_INET
> + if (val)
> + tcp_sk(sk)->bpf_sock_ops_cb_flags = val;
> +
> + return argval & (~BPF_SOCK_OPS_ALL_CB_FLAGS);
interesting idea! took me some time to realize the potential
of such semantics, but now I like it a lot.
It blends 'set good flag' with 'which flags are supported' logic
into single helper. Nice.
Thanks for adding a test for both ways.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Eric, does this approach address your concerns?
next prev parent reply other threads:[~2018-01-20 3:52 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-20 1:45 [PATCH bpf-next v6 00/11] bpf: More sock_ops callbacks Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 01/11] bpf: Make SOCK_OPS_GET_TCP size independent Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 02/11] bpf: Make SOCK_OPS_GET_TCP struct independent Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 03/11] bpf: Add write access to tcp_sock and sock fields Lawrence Brakmo
2018-01-20 3:54 ` Alexei Starovoitov
2018-01-20 1:45 ` [PATCH bpf-next v6 04/11] bpf: Support passing args to sock_ops bpf function Lawrence Brakmo
2018-01-24 1:11 ` Daniel Borkmann
2018-01-24 1:30 ` Lawrence Brakmo
2018-01-24 1:34 ` Daniel Borkmann
2018-01-20 1:45 ` [PATCH bpf-next v6 05/11] bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock Lawrence Brakmo
2018-01-20 3:52 ` Alexei Starovoitov [this message]
2018-01-20 7:50 ` Lawrence Brakmo
2018-01-23 17:29 ` Eric Dumazet
2018-01-20 1:45 ` [PATCH bpf-next v6 06/11] bpf: Add sock_ops RTO callback Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 07/11] bpf: Add support for reading sk_state and more Lawrence Brakmo
2018-01-24 1:05 ` Daniel Borkmann
2018-01-24 1:27 ` Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 08/11] bpf: Add sock_ops R/W access to tclass & sk_txhash Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 09/11] bpf: Add BPF_SOCK_OPS_RETRANS_CB Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 10/11] bpf: Add BPF_SOCK_OPS_STATE_CB Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 11/11] bpf: add selftest for tcpbpf Lawrence Brakmo
2018-01-20 3:59 ` Alexei Starovoitov
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