diff options
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/syncookies.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 02bef6aa8b30..51b5662545d6 100644 --- 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 */ |