syncookies: avoid unneeded tcp header flag double check

caller: if (!th->rst && !th->syn && th->ack)
callee: if (!th->ack)

make the caller only check for !syn (common for 3whs), and move
the !rst / ack test to the callee.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 4 insertions, 4 deletions

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 5c24db4a3c91..c9dac8615958 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -266,7 +266,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
         struct rtable *rt;
         __u8 rcv_wscale;
 
-        if (!sysctl_tcp_syncookies || !th->ack)
+        if (!sysctl_tcp_syncookies || !th->ack || th->rst)
                 goto out;
 
         if (tcp_synq_no_recent_overflow(sk) ||
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a13f881e5037..6558dfd899da 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1506,7 +1506,7 @@ static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
         }
 
 #ifdef CONFIG_SYN_COOKIES
-        if (!th->rst && !th->syn && th->ack)
+        if (!th->syn)
                 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
 #endif
         return sk;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 12383705dbad..9fcb3ec7c838 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -174,7 +174,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
         struct dst_entry *dst;
         __u8 rcv_wscale;
 
-        if (!sysctl_tcp_syncookies || !th->ack)
+        if (!sysctl_tcp_syncookies || !th->ack || th->rst)
                 goto out;
 
         if (tcp_synq_no_recent_overflow(sk) ||
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e487080d02db..5887141ad641 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1157,7 +1157,7 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
         }
 
 #ifdef CONFIG_SYN_COOKIES
-        if (!th->rst && !th->syn && th->ack)
+        if (!th->syn)
                 sk = cookie_v6_check(sk, skb);
 #endif
         return sk;