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authorMartin KaFai Lau <kafai@fb.com>2020-08-20 21:01:23 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-08-24 23:35:00 +0200
commit267cf9fa43d1c9d525d5d818a8651f2900e3aa9e (patch)
treeb1faac2bd96331562c4ef6cd40e05c4947d13969 /net/ipv4/tcp_input.c
parentbpf: selftests: Tcp header options (diff)
downloadlinux-267cf9fa43d1c9d525d5d818a8651f2900e3aa9e.tar.xz
linux-267cf9fa43d1c9d525d5d818a8651f2900e3aa9e.zip
tcp: bpf: Optionally store mac header in TCP_SAVE_SYN
This patch is adapted from Eric's patch in an earlier discussion [1]. The TCP_SAVE_SYN currently only stores the network header and tcp header. This patch allows it to optionally store the mac header also if the setsockopt's optval is 2. It requires one more bit for the "save_syn" bit field in tcp_sock. This patch achieves this by moving the syn_smc bit next to the is_mptcp. The syn_smc is currently used with the TCP experimental option. Since syn_smc is only used when CONFIG_SMC is enabled, this patch also puts the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did with "IS_ENABLED(CONFIG_MPTCP)". The mac_hdrlen is also stored in the "struct saved_syn" to allow a quick offset from the bpf prog if it chooses to start getting from the network header or the tcp header. [1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/ Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/bpf/20200820190123.2886935-1-kafai@fb.com
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 319cc7fd5117..4337841faeff 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6676,13 +6676,25 @@ static void tcp_reqsk_record_syn(const struct sock *sk,
if (tcp_sk(sk)->save_syn) {
u32 len = skb_network_header_len(skb) + tcp_hdrlen(skb);
struct saved_syn *saved_syn;
+ u32 mac_hdrlen;
+ void *base;
+
+ if (tcp_sk(sk)->save_syn == 2) { /* Save full header. */
+ base = skb_mac_header(skb);
+ mac_hdrlen = skb_mac_header_len(skb);
+ len += mac_hdrlen;
+ } else {
+ base = skb_network_header(skb);
+ mac_hdrlen = 0;
+ }
saved_syn = kmalloc(struct_size(saved_syn, data, len),
GFP_ATOMIC);
if (saved_syn) {
+ saved_syn->mac_hdrlen = mac_hdrlen;
saved_syn->network_hdrlen = skb_network_header_len(skb);
saved_syn->tcp_hdrlen = tcp_hdrlen(skb);
- memcpy(saved_syn->data, skb_network_header(skb), len);
+ memcpy(saved_syn->data, base, len);
req->saved_syn = saved_syn;
}
}