diff options
Diffstat (limited to 'net/ipv4/syncookies.c')
-rw-r--r-- | net/ipv4/syncookies.c | 48 |
1 files changed, 24 insertions, 24 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 5c24db4..02bef6a 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -138,23 +138,23 @@ static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr, } /* - * This table has to be sorted and terminated with (__u16)-1. - * XXX generate a better table. - * Unresolved Issues: HIPPI with a 64k MSS is not well supported. + * MSS Values are taken from the 2009 paper + * 'Measuring TCP Maximum Segment Size' by S. Alcock and R. Nelson: + * - values 1440 to 1460 accounted for 80% of observed mss values + * - values outside the 536-1460 range are rare (<0.2%). + * + * Table must be sorted. */ static __u16 const msstab[] = { - 64 - 1, - 256 - 1, - 512 - 1, - 536 - 1, - 1024 - 1, - 1440 - 1, - 1460 - 1, - 4312 - 1, - (__u16)-1 + 64, + 512, + 536, + 1024, + 1440, + 1460, + 4312, + 8960, }; -/* The number doesn't include the -1 terminator */ -#define NUM_MSS (ARRAY_SIZE(msstab) - 1) /* * Generate a syncookie. mssp points to the mss, which is returned @@ -169,10 +169,10 @@ __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp) tcp_synq_overflow(sk); - /* XXX sort msstab[] by probability? Binary search? */ - for (mssind = 0; mss > msstab[mssind + 1]; mssind++) - ; - *mssp = msstab[mssind] + 1; + for (mssind = ARRAY_SIZE(msstab) - 1; mssind ; mssind--) + if (mss >= msstab[mssind]) + break; + *mssp = msstab[mssind]; NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); @@ -202,7 +202,7 @@ static inline int cookie_check(struct sk_buff *skb, __u32 cookie) jiffies / (HZ * 60), COUNTER_TRIES); - return mssind < NUM_MSS ? msstab[mssind] + 1 : 0; + return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0; } static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb, @@ -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) || @@ -347,22 +347,22 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, { .sport = th->dest, .dport = th->source } } }; security_req_classify_flow(req, &fl); - if (ip_route_output_key(&init_net, &rt, &fl)) { + if (ip_route_output_key(sock_net(sk), &rt, &fl)) { reqsk_free(req); goto out; } } /* Try to redo what tcp_v4_send_synack did. */ - req->window_clamp = tp->window_clamp ? :dst_metric(&rt->u.dst, RTAX_WINDOW); + req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW); tcp_select_initial_window(tcp_full_space(sk), req->mss, &req->rcv_wnd, &req->window_clamp, ireq->wscale_ok, &rcv_wscale, - dst_metric(&rt->u.dst, RTAX_INITRWND)); + dst_metric(&rt->dst, RTAX_INITRWND)); ireq->rcv_wscale = rcv_wscale; - ret = get_cookie_sock(sk, skb, req, &rt->u.dst); + ret = get_cookie_sock(sk, skb, req, &rt->dst); out: return ret; } |