diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-05-04 07:34:46 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-05 23:02:34 +0300 |
| commit | cd8ae85299d54155702a56811b2e035e63064d3d (patch) | |
| tree | aaec550c619b58c87f2981190e2c04a454650ce7 /include/net/request_sock.h | |
| parent | fcba67c94abe83e0e69a65737000ccbb16a4fa03 (diff) | |
| download | linux-cd8ae85299d54155702a56811b2e035e63064d3d.tar.xz | |
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 'include/net/request_sock.h')
| -rw-r--r-- | include/net/request_sock.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/net/request_sock.h b/include/net/request_sock.h index 9f4265ce8892..87935cad2f7b 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -64,6 +64,7 @@ struct request_sock { struct timer_list rsk_timer; const struct request_sock_ops *rsk_ops; struct sock *sk; + u32 *saved_syn; u32 secid; u32 peer_secid; }; @@ -77,7 +78,7 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener) req->rsk_ops = ops; sock_hold(sk_listener); req->rsk_listener = sk_listener; - + req->saved_syn = NULL; /* Following is temporary. It is coupled with debugging * helpers in reqsk_put() & reqsk_free() */ @@ -104,6 +105,7 @@ static inline void reqsk_free(struct request_sock *req) req->rsk_ops->destructor(req); if (req->rsk_listener) sock_put(req->rsk_listener); + kfree(req->saved_syn); kmem_cache_free(req->rsk_ops->slab, req); } |