netdev - Re: [PATCH bpf-next v6 04/11] bpf: Support passing args to sock

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Message-ID: <DB7C8DF2-3567-4715-9793-56639F379B8F@fb.com>
Date:   Wed, 24 Jan 2018 01:30:54 +0000
From:   Lawrence Brakmo <brakmo@...com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        netdev <netdev@...r.kernel.org>
CC:     Kernel Team <Kernel-team@...com>, Blake Matheny <bmatheny@...com>,
        "Alexei Starovoitov" <ast@...com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        "Neal Cardwell" <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>
Subject: Re: [PATCH bpf-next v6 04/11] bpf: Support passing args to sock_ops
 bpf function

On 1/23/18, 5:11 PM, "Daniel Borkmann" <daniel@...earbox.net> wrote:

    On 01/20/2018 02:45 AM, Lawrence Brakmo wrote:
    > Adds support for passing up to 4 arguments to sock_ops bpf functions. It
    > reusues the reply union, so the bpf_sock_ops structures are not
    > increased in size.
    > 
    > Signed-off-by: Lawrence Brakmo <brakmo@...com>
    > ---
    >  include/linux/filter.h   |  1 +
    >  include/net/tcp.h        | 64 ++++++++++++++++++++++++++++++++++++++++++++----
    >  include/uapi/linux/bpf.h |  5 ++--
    >  net/ipv4/tcp.c           |  2 +-
    >  net/ipv4/tcp_nv.c        |  2 +-
    >  net/ipv4/tcp_output.c    |  2 +-
    >  6 files changed, 66 insertions(+), 10 deletions(-)
    > 
    > diff --git a/include/linux/filter.h b/include/linux/filter.h
    > index daa5a67..20384c4 100644
    > --- a/include/linux/filter.h
    > +++ b/include/linux/filter.h
    > @@ -1003,6 +1003,7 @@ struct bpf_sock_ops_kern {
    >  	struct	sock *sk;
    >  	u32	op;
    >  	union {
    > +		u32 args[4];
    >  		u32 reply;
    >  		u32 replylong[4];
    >  	};
    > diff --git a/include/net/tcp.h b/include/net/tcp.h
    > index 108d16a..8e9111f 100644
    > --- a/include/net/tcp.h
    > +++ b/include/net/tcp.h
    > @@ -2005,7 +2005,7 @@ void tcp_cleanup_ulp(struct sock *sk);
    >   * program loaded).
    >   */
    >  #ifdef CONFIG_BPF
    > -static inline int tcp_call_bpf(struct sock *sk, int op)
    > +static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
    >  {
    >  	struct bpf_sock_ops_kern sock_ops;
    >  	int ret;
    > @@ -2018,6 +2018,8 @@ static inline int tcp_call_bpf(struct sock *sk, int op)
    >  
    >  	sock_ops.sk = sk;
    >  	sock_ops.op = op;
    > +	if (nargs > 0)
    > +		memcpy(sock_ops.args, args, nargs*sizeof(u32));
    
    Small nit given respin: nargs * sizeof(*args)

Thanks, will fix.
    
    >  	ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
    >  	if (ret == 0)
    > @@ -2026,18 +2028,70 @@ static inline int tcp_call_bpf(struct sock *sk, int op)
    >  		ret = -1;
    >  	return ret;
    >  }
    > +
    > +static inline int tcp_call_bpf_1arg(struct sock *sk, int op, u32 arg)
    > +{
    > +	return tcp_call_bpf(sk, op, 1, &arg);
    > +}
    > +
    > +static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
    > +{
    > +	u32 args[2] = {arg1, arg2};
    > +
    > +	return tcp_call_bpf(sk, op, 2, args);
    > +}
    > +
    > +static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
    > +				    u32 arg3)
    > +{
    > +	u32 args[3] = {arg1, arg2, arg3};
    > +
    > +	return tcp_call_bpf(sk, op, 3, args);
    > +}
    > +
    > +static inline int tcp_call_bpf_4arg(struct sock *sk, int op, u32 arg1, u32 arg2,
    > +				    u32 arg3, u32 arg4)
    > +{
    > +	u32 args[4] = {arg1, arg2, arg3, arg4};
    > +
    > +	return tcp_call_bpf(sk, op, 4, args);
    > +}
    > +
    >  #else
    > -static inline int tcp_call_bpf(struct sock *sk, int op)
    > +static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
    >  {
    >  	return -EPERM;
    >  }
    > +
    > +static inline int tcp_call_bpf_1arg(struct sock *sk, int op, u32 arg)
    > +{
    > +	return -EPERM;
    > +}
    > +
    > +static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
    > +{
    > +	return -EPERM;
    > +}
    > +
    > +static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
    > +	u32 arg3)
    
    indent: arg3

OK
    
    > +{
    > +	return -EPERM;
    > +}
    > +
    > +static inline int tcp_call_bpf_4arg(struct sock *sk, int op, u32 arg1, u32 arg2,
    > +				    u32 arg3, u32 arg4)
    > +{
    > +	return -EPERM;
    > +}
    > +
    >  #endif
    
    tcp_call_bpf_1arg() and tcp_call_bpf_4arg() unused for the time being?

Yes, I just thought I should add them for completeness. Should I remove them until
they are actually used?