tcp: Change possible SYN flooding messages
"Possible SYN flooding on port xxxx " messages can fill logs on servers.
Change logic to log the message only once per listener, and add two new
SNMP counters to track :
TCPReqQFullDoCookies : number of times a SYNCOOKIE was replied to client
TCPReqQFullDrop : number of times a SYN request was dropped because
syncookies were not enabled.
Based on a prior patch from Tom Herbert, and suggestions from David.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index 12b2b18..e16557a 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -231,6 +231,8 @@
LINUX_MIB_TCPDEFERACCEPTDROP,
LINUX_MIB_IPRPFILTER, /* IP Reverse Path Filter (rp_filter) */
LINUX_MIB_TCPTIMEWAITOVERFLOW, /* TCPTimeWaitOverflow */
+ LINUX_MIB_TCPREQQFULLDOCOOKIES, /* TCPReqQFullDoCookies */
+ LINUX_MIB_TCPREQQFULLDROP, /* TCPReqQFullDrop */
__LINUX_MIB_MAX
};
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 99e6e19..4c0766e 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -96,7 +96,8 @@
*/
struct listen_sock {
u8 max_qlen_log;
- /* 3 bytes hole, try to use */
+ u8 synflood_warned;
+ /* 2 bytes hole, try to use */
int qlen;
int qlen_young;
int clock_hand;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 149a415..e9b48b0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -460,6 +460,9 @@
extern void tcp_send_fin(struct sock *sk);
extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
extern int tcp_send_synack(struct sock *);
+extern int tcp_syn_flood_action(struct sock *sk,
+ const struct sk_buff *skb,
+ const char *proto);
extern void tcp_push_one(struct sock *, unsigned int mss_now);
extern void tcp_send_ack(struct sock *sk);
extern void tcp_send_delayed_ack(struct sock *sk);