syncookies: check decoded options against sysctl settings

[pandora-kernel.git] / net / ipv4 / syncookies.c

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 02bef6a..51b5662 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -230,23 +230,36 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
  * The lowest 4 bits are for snd_wscale
  * The next 4 lsb are for rcv_wscale
  * The next lsb is for sack_ok
+ *
+ * return false if we decode an option that should not be.
  */
-void cookie_check_timestamp(struct tcp_options_received *tcp_opt)
+bool cookie_check_timestamp(struct tcp_options_received *tcp_opt)
 {
        /* echoed timestamp, 9 lowest bits contain options */
        u32 options = tcp_opt->rcv_tsecr & TSMASK;
 
+       if (!tcp_opt->saw_tstamp)  {
+               tcp_clear_options(tcp_opt);
+               return true;
+       }
+
+       if (!sysctl_tcp_timestamps)
+               return false;
+
        tcp_opt->snd_wscale = options & 0xf;
        options >>= 4;
        tcp_opt->rcv_wscale = options & 0xf;
 
        tcp_opt->sack_ok = (options >> 4) & 0x1;
 
-       if (tcp_opt->sack_ok)
-               tcp_sack_reset(tcp_opt);
+       if (tcp_opt->sack_ok && !sysctl_tcp_sack)
+               return false;
 
-       if (tcp_opt->snd_wscale || tcp_opt->rcv_wscale)
+       if (tcp_opt->snd_wscale || tcp_opt->rcv_wscale) {
                tcp_opt->wscale_ok = 1;
+               return sysctl_tcp_window_scaling != 0;
+       }
+       return true;
 }
 EXPORT_SYMBOL(cookie_check_timestamp);
 
@@ -281,8 +294,8 @@ 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 (tcp_opt.saw_tstamp)
-               cookie_check_timestamp(&tcp_opt);
+       if (!cookie_check_timestamp(&tcp_opt))
+               goto out;
 
        ret = NULL;
        req = inet_reqsk_alloc(&tcp_request_sock_ops); /* for safety */