From: "Nikita V. Shirokov" <tehnerd@fb.com>
Date: Thu, 30 Aug 2018 07:51:53 -0700
Subject: bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN options for bpf_(set|get)sockopt
Patch-mainline: v4.20-rc1
Git-commit: 1e215300f1384072c62459a1c194a08dbe05ff2c
References: bsc#1109837
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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/core/filter.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3973,6 +3973,12 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_so
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;
}
@@ -3998,21 +4004,32 @@ static const struct bpf_func_proto bpf_s
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) {