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bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN options for bpf_(set|get)sockopt

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Adding support for two new bpf get/set sockopts: TCP_SAVE_SYN (set)
and TCP_SAVED_SYN (get). This would allow for bpf program to build
logic based on data from ingress SYN packet (e.g. doing tcp's tos/
tclass reflection (see sample prog)) and do it transparently from
userspace program point of view.

Signed-off-by: Nikita V. Shirokov <tehnerd@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Nikita V. Shirokov 2018-08-30 07:51:53 -07:00 committed by Daniel Borkmann
parent 7296216776
commit 1e215300f1
1 changed files with 21 additions and 4 deletions
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25
net/core/filter.c
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@ -4007,6 +4007,12 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
tp->snd_ssthresh = val;
}
break;
case TCP_SAVE_SYN:
if (val < 0 || val > 1)
ret = -EINVAL;
else
tp->save_syn = val;
break;
default:
ret = -EINVAL;
}
@ -4032,21 +4038,32 @@ static const struct bpf_func_proto bpf_setsockopt_proto = {
BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
{
struct inet_connection_sock *icsk;
struct sock *sk = bpf_sock->sk;
struct tcp_sock *tp;
if (!sk_fullsock(sk))
goto err_clear;
#ifdef CONFIG_INET
if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
if (optname == TCP_CONGESTION) {
struct inet_connection_sock *icsk = inet_csk(sk);
switch (optname) {
case TCP_CONGESTION:
icsk = inet_csk(sk);
if (!icsk->icsk_ca_ops || optlen <= 1)
goto err_clear;
strncpy(optval, icsk->icsk_ca_ops->name, optlen);
optval[optlen - 1] = 0;
} else {
break;
case TCP_SAVED_SYN:
tp = tcp_sk(sk);
if (optlen <= 0 || !tp->saved_syn ||
optlen > tp->saved_syn[0])
goto err_clear;
memcpy(optval, tp->saved_syn + 1, optlen);
break;
default:
goto err_clear;
}
} else if (level == SOL_IP) {