diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/tcp.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 0e47551..de870ee 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -481,6 +481,24 @@ int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, struct ip_options *opt); #ifdef CONFIG_SYN_COOKIES +#include <linux/ktime.h> + +/* Syncookies use a monotonic timer which increments every 64 seconds. + * This counter is used both as a hash input and partially encoded into + * the cookie value. A cookie is only validated further if the delta + * between the current counter value and the encoded one is less than this, + * i.e. a sent cookie is valid only at most for 128 seconds (or less if + * the counter advances immediately after a cookie is generated). + */ +#define MAX_SYNCOOKIE_AGE 2 + +static inline u32 tcp_cookie_time(void) +{ + struct timespec now; + getnstimeofday(&now); + return now.tv_sec >> 6; /* 64 seconds granularity */ +} + u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, u16 *mssp); __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss); |