From c6aefafb7ec620911d46174eed514f9df639e5a4 Mon Sep 17 00:00:00 2001 From: Glenn Griffin Date: Thu, 7 Feb 2008 21:49:26 -0800 Subject: [TCP]: Add IPv6 support to TCP SYN cookies Updated to incorporate Eric's suggestion of using a per cpu buffer rather than allocating on the stack. Just a two line change, but will resend in it's entirety. Signed-off-by: Glenn Griffin Signed-off-by: YOSHIFUJI Hideaki --- net/ipv6/tcp_ipv6.c | 77 ++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 55 insertions(+), 22 deletions(-) (limited to 'net/ipv6/tcp_ipv6.c') diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 1cbbb87dbad2..fd773ac7531a 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -512,6 +512,20 @@ done: return err; } +static inline void syn_flood_warning(struct sk_buff *skb) +{ +#ifdef CONFIG_SYN_COOKIES + if (sysctl_tcp_syncookies) + printk(KERN_INFO + "TCPv6: Possible SYN flooding on port %d. " + "Sending cookies.\n", ntohs(tcp_hdr(skb)->dest)); + else +#endif + printk(KERN_INFO + "TCPv6: Possible SYN flooding on port %d. " + "Dropping request.\n", ntohs(tcp_hdr(skb)->dest)); +} + static void tcp_v6_reqsk_destructor(struct request_sock *req) { if (inet6_rsk(req)->pktopts) @@ -915,7 +929,7 @@ done_opts: } #endif -static struct request_sock_ops tcp6_request_sock_ops __read_mostly = { +struct request_sock_ops tcp6_request_sock_ops __read_mostly = { .family = AF_INET6, .obj_size = sizeof(struct tcp6_request_sock), .rtx_syn_ack = tcp_v6_send_synack, @@ -1213,9 +1227,9 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb) return NULL; } -#if 0 /*def CONFIG_SYN_COOKIES*/ +#ifdef CONFIG_SYN_COOKIES if (!th->rst && !th->syn && th->ack) - sk = cookie_v6_check(sk, skb, &(IPCB(skb)->opt)); + sk = cookie_v6_check(sk, skb); #endif return sk; } @@ -1231,6 +1245,11 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) struct tcp_sock *tp = tcp_sk(sk); struct request_sock *req = NULL; __u32 isn = TCP_SKB_CB(skb)->when; +#ifdef CONFIG_SYN_COOKIES + int want_cookie = 0; +#else +#define want_cookie 0 +#endif if (skb->protocol == htons(ETH_P_IP)) return tcp_v4_conn_request(sk, skb); @@ -1238,12 +1257,14 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) if (!ipv6_unicast_destination(skb)) goto drop; - /* - * There are no SYN attacks on IPv6, yet... - */ if (inet_csk_reqsk_queue_is_full(sk) && !isn) { if (net_ratelimit()) - printk(KERN_INFO "TCPv6: dropping request, synflood is possible\n"); + syn_flood_warning(skb); +#ifdef CONFIG_SYN_COOKIES + if (sysctl_tcp_syncookies) + want_cookie = 1; + else +#endif goto drop; } @@ -1264,29 +1285,39 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) tcp_parse_options(skb, &tmp_opt, 0); + if (want_cookie) { + tcp_clear_options(&tmp_opt); + tmp_opt.saw_tstamp = 0; + } + tmp_opt.tstamp_ok = tmp_opt.saw_tstamp; tcp_openreq_init(req, &tmp_opt, skb); treq = inet6_rsk(req); ipv6_addr_copy(&treq->rmt_addr, &ipv6_hdr(skb)->saddr); ipv6_addr_copy(&treq->loc_addr, &ipv6_hdr(skb)->daddr); - TCP_ECN_create_request(req, tcp_hdr(skb)); treq->pktopts = NULL; - if (ipv6_opt_accepted(sk, skb) || - np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo || - np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) { - atomic_inc(&skb->users); - treq->pktopts = skb; - } - treq->iif = sk->sk_bound_dev_if; + if (!want_cookie) + TCP_ECN_create_request(req, tcp_hdr(skb)); + + if (want_cookie) { + isn = cookie_v6_init_sequence(sk, skb, &req->mss); + } else if (!isn) { + if (ipv6_opt_accepted(sk, skb) || + np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo || + np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) { + atomic_inc(&skb->users); + treq->pktopts = skb; + } + treq->iif = sk->sk_bound_dev_if; - /* So that link locals have meaning */ - if (!sk->sk_bound_dev_if && - ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL) - treq->iif = inet6_iif(skb); + /* So that link locals have meaning */ + if (!sk->sk_bound_dev_if && + ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL) + treq->iif = inet6_iif(skb); - if (isn == 0) isn = tcp_v6_init_sequence(skb); + } tcp_rsk(req)->snt_isn = isn; @@ -1295,8 +1326,10 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) if (tcp_v6_send_synack(sk, req)) goto drop; - inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); - return 0; + if (!want_cookie) { + inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); + return 0; + } drop: if (req) -- cgit v1.2.2