From e802af9cabb011f09b9c19a82faef3dd315f27eb Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 22 Apr 2010 15:24:53 -0700 Subject: [PATCH] IPv6: Generic TTL Security Mechanism (final version) This patch adds IPv6 support for RFC5082 Generalized TTL Security Mechanism. Not to users of mapped address; the IPV6 and IPV4 socket options are seperate. The server does have to deal with both IPv4 and IPv6 socket options and the client has to handle the different for each family. On client: int ttl = 255; getaddrinfo(argv[1], argv[2], &hint, &result); for (rp = result; rp != NULL; rp = rp->ai_next) { s = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol); if (s < 0) continue; if (rp->ai_family == AF_INET) { setsockopt(s, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); } else if (rp->ai_family == AF_INET6) { setsockopt(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl))) } if (connect(s, rp->ai_addr, rp->ai_addrlen) == 0) { ... On server: int minttl = 255 - maxhops; getaddrinfo(NULL, port, &hints, &result); for (rp = result; rp != NULL; rp = rp->ai_next) { s = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol); if (s < 0) continue; if (rp->ai_family == AF_INET6) setsockopt(s, IPPROTO_IPV6, IPV6_MINHOPCOUNT, &minttl, sizeof(minttl)); setsockopt(s, IPPROTO_IP, IP_MINTTL, &minttl, sizeof(minttl)); if (bind(s, rp->ai_addr, rp->ai_addrlen) == 0) break ... Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- include/linux/in6.h | 3 +++ include/linux/ipv6.h | 1 + net/ipv6/ipv6_sockglue.c | 12 ++++++++++++ net/ipv6/tcp_ipv6.c | 14 +++++++++++++- 4 files changed, 29 insertions(+), 1 deletion(-) diff --git a/include/linux/in6.h b/include/linux/in6.h index bd55c6e46b2e..9b90cb296eb1 100644 --- a/include/linux/in6.h +++ b/include/linux/in6.h @@ -265,6 +265,9 @@ struct in6_flowlabel_req { #define IPV6_PREFER_SRC_CGA 0x0008 #define IPV6_PREFER_SRC_NONCGA 0x0800 +/* RFC5082: Generalized Ttl Security Mechanism */ +#define IPV6_MINHOPCOUNT 73 + /* * Multicast Routing: * see include/linux/mroute6.h. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index e0cc9a7db2b5..1bdbebf08d16 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -348,6 +348,7 @@ struct ipv6_pinfo { * 010: prefer public address * 100: prefer care-of address */ + __u8 min_hopcount; __u8 tclass; __u32 dst_cookie; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 1160400e9dbd..92295ad3487a 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -767,6 +767,14 @@ pref_skip_coa: break; } + case IPV6_MINHOPCOUNT: + if (optlen < sizeof(int)) + goto e_inval; + if (val < 0 || val > 255) + goto e_inval; + np->min_hopcount = val; + retv = 0; + break; } release_sock(sk); @@ -1116,6 +1124,10 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname, val |= IPV6_PREFER_SRC_HOME; break; + case IPV6_MINHOPCOUNT: + val = np->min_hopcount; + break; + default: return -ENOPROTOOPT; } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 1ababbb41131..6603511e3673 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -353,6 +353,11 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, if (sk->sk_state == TCP_CLOSE) goto out; + if (ipv6_hdr(skb)->hop_limit < inet6_sk(sk)->min_hopcount) { + NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP); + goto out; + } + tp = tcp_sk(sk); seq = ntohl(th->seq); if (sk->sk_state != TCP_LISTEN && @@ -1678,6 +1683,7 @@ ipv6_pktoptions: static int tcp_v6_rcv(struct sk_buff *skb) { struct tcphdr *th; + struct ipv6hdr *hdr; struct sock *sk; int ret; struct net *net = dev_net(skb->dev); @@ -1704,12 +1710,13 @@ static int tcp_v6_rcv(struct sk_buff *skb) goto bad_packet; th = tcp_hdr(skb); + hdr = ipv6_hdr(skb); TCP_SKB_CB(skb)->seq = ntohl(th->seq); TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff*4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); TCP_SKB_CB(skb)->when = 0; - TCP_SKB_CB(skb)->flags = ipv6_get_dsfield(ipv6_hdr(skb)); + TCP_SKB_CB(skb)->flags = ipv6_get_dsfield(hdr); TCP_SKB_CB(skb)->sacked = 0; sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest); @@ -1720,6 +1727,11 @@ process: if (sk->sk_state == TCP_TIME_WAIT) goto do_time_wait; + if (hdr->hop_limit < inet6_sk(sk)->min_hopcount) { + NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP); + goto discard_and_relse; + } + if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; -- 2.30.2