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authorFlorian Westphal <fw@strlen.de>2010-06-21 11:48:45 +0000
committerDavid S. Miller <davem@davemloft.net>2010-06-26 22:00:03 -0700
commit172d69e63c7f1e8300d0e1c1bbd8eb0f630faa15 (patch)
treec71118ddc86186e235a920b9529c457db5e9aae5 /net/ipv4/syncookies.c
parent734f614bc1e7c6bf075d201f6bd9a555b8b4a984 (diff)
syncookies: add support for ECN
Allows use of ECN when syncookies are in effect by encoding ecn_ok into the syn-ack tcp timestamp. While at it, remove a uneeded #ifdef CONFIG_SYN_COOKIES. With CONFIG_SYN_COOKIES=nm want_cookie is ifdef'd to 0 and gcc removes the "if (0)". Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/syncookies.c')
-rw-r--r--net/ipv4/syncookies.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 8896329aebd0..650cace2180d 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -19,7 +19,7 @@
#include <net/route.h>
/* Timestamps: lowest bits store TCP options */
-#define TSBITS 5
+#define TSBITS 6
#define TSMASK (((__u32)1 << TSBITS) - 1)
extern int sysctl_tcp_syncookies;
@@ -73,6 +73,7 @@ __u32 cookie_init_timestamp(struct request_sock *req)
options = ireq->wscale_ok ? ireq->snd_wscale : 0xf;
options |= ireq->sack_ok << 4;
+ options |= ireq->ecn_ok << 5;
ts = ts_now & ~TSMASK;
ts |= options;
@@ -226,11 +227,11 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
* This extracts these options from the timestamp echo.
*
* The lowest 4 bits store snd_wscale.
- * The next lsb is for sack_ok
+ * next 2 bits indicate SACK and ECN support.
*
* return false if we decode an option that should not be.
*/
-bool cookie_check_timestamp(struct tcp_options_received *tcp_opt)
+bool cookie_check_timestamp(struct tcp_options_received *tcp_opt, bool *ecn_ok)
{
/* echoed timestamp, lowest bits contain options */
u32 options = tcp_opt->rcv_tsecr & TSMASK;
@@ -244,6 +245,9 @@ bool cookie_check_timestamp(struct tcp_options_received *tcp_opt)
return false;
tcp_opt->sack_ok = (options >> 4) & 0x1;
+ *ecn_ok = (options >> 5) & 1;
+ if (*ecn_ok && !sysctl_tcp_ecn)
+ return false;
if (tcp_opt->sack_ok && !sysctl_tcp_sack)
return false;
@@ -272,6 +276,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
int mss;
struct rtable *rt;
__u8 rcv_wscale;
+ bool ecn_ok;
if (!sysctl_tcp_syncookies || !th->ack || th->rst)
goto out;
@@ -288,7 +293,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
memset(&tcp_opt, 0, sizeof(tcp_opt));
tcp_parse_options(skb, &tcp_opt, &hash_location, 0);
- if (!cookie_check_timestamp(&tcp_opt))
+ if (!cookie_check_timestamp(&tcp_opt, &ecn_ok))
goto out;
ret = NULL;
@@ -305,7 +310,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
ireq->rmt_port = th->source;
ireq->loc_addr = ip_hdr(skb)->daddr;
ireq->rmt_addr = ip_hdr(skb)->saddr;
- ireq->ecn_ok = 0;
+ ireq->ecn_ok = ecn_ok;
ireq->snd_wscale = tcp_opt.snd_wscale;
ireq->sack_ok = tcp_opt.sack_ok;
ireq->wscale_ok = tcp_opt.wscale_ok;