diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-05-03 21:34:46 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-05 16:02:34 -0400 |
| commit | cd8ae85299d54155702a56811b2e035e63064d3d (patch) | |
| tree | aaec550c619b58c87f2981190e2c04a454650ce7 /net/ipv4/tcp_ipv4.c | |
| parent | fcba67c94abe83e0e69a65737000ccbb16a4fa03 (diff) | |
| download | op-kernel-dev-cd8ae85299d54155702a56811b2e035e63064d3d.zip op-kernel-dev-cd8ae85299d54155702a56811b2e035e63064d3d.tar.gz | |
tcp: provide SYN headers for passive connections
This patch allows a server application to get the TCP SYN headers for
its passive connections. This is useful if the server is doing
fingerprinting of clients based on SYN packet contents.
Two socket options are added: TCP_SAVE_SYN and TCP_SAVED_SYN.
The first is used on a socket to enable saving the SYN headers
for child connections. This can be set before or after the listen()
call.
The latter is used to retrieve the SYN headers for passive connections,
if the parent listener has enabled TCP_SAVE_SYN.
TCP_SAVED_SYN is read once, it frees the saved SYN headers.
The data returned in TCP_SAVED_SYN are network (IPv4/IPv6) and TCP
headers.
Original patch was written by Tom Herbert, I changed it to not hold
a full skb (and associated dst and conntracking reference).
We have used such patch for about 3 years at Google.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Tested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index fc1c658..91cb476 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1802,6 +1802,7 @@ void tcp_v4_destroy_sock(struct sock *sk) /* If socket is aborted during connect operation */ tcp_free_fastopen_req(tp); + tcp_saved_syn_free(tp); sk_sockets_allocated_dec(sk); sock_release_memcg(sk); |
