bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN options for bpf_(set|get)sockopt
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>
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@ -4007,6 +4007,12 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
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tp->snd_ssthresh = val;
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}
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break;
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case TCP_SAVE_SYN:
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if (val < 0 || val > 1)
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ret = -EINVAL;
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else
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tp->save_syn = val;
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break;
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default:
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ret = -EINVAL;
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}
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@ -4032,21 +4038,32 @@ static const struct bpf_func_proto bpf_setsockopt_proto = {
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BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
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int, level, int, optname, char *, optval, int, optlen)
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{
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struct inet_connection_sock *icsk;
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struct sock *sk = bpf_sock->sk;
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struct tcp_sock *tp;
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if (!sk_fullsock(sk))
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goto err_clear;
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#ifdef CONFIG_INET
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if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
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if (optname == TCP_CONGESTION) {
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struct inet_connection_sock *icsk = inet_csk(sk);
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switch (optname) {
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case TCP_CONGESTION:
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icsk = inet_csk(sk);
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if (!icsk->icsk_ca_ops || optlen <= 1)
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goto err_clear;
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strncpy(optval, icsk->icsk_ca_ops->name, optlen);
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optval[optlen - 1] = 0;
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} else {
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break;
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case TCP_SAVED_SYN:
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tp = tcp_sk(sk);
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if (optlen <= 0 || !tp->saved_syn ||
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optlen > tp->saved_syn[0])
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goto err_clear;
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memcpy(optval, tp->saved_syn + 1, optlen);
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break;
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default:
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goto err_clear;
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}
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} else if (level == SOL_IP) {
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