diff options
| author | Stephen Hemminger <shemminger@vyatta.com> | 2010-01-11 16:28:01 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-01-11 16:28:01 -0800 |
| commit | d218d11133d888f9745802146a50255a4781d37a (patch) | |
| tree | 3b4b163238e19c48f37f3d8a77eb27f3a18691a0 | |
| parent | c8e000604bce02a87742240a9b716a0f1b680c0b (diff) | |
tcp: Generalized TTL Security Mechanism
This patch adds the kernel portions needed to implement
RFC 5082 Generalized TTL Security Mechanism (GTSM).
It is a lightweight security measure against forged
packets causing DoS attacks (for BGP).
This is already implemented the same way in BSD kernels.
For the necessary Quagga patch
http://www.gossamer-threads.com/lists/quagga/dev/17389
Description from Cisco
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t7/feature/guide/gt_btsh.html
It does add one byte to each socket structure, but I did
a little rearrangement to reuse a hole (on 64 bit), but it
does grow the structure on 32 bit
This should be documented on ip(4) man page and the Glibc in.h
file also needs update. IPV6_MINHOPLIMIT should also be added
(although BSD doesn't support that).
Only TCP is supported, but could also be added to UDP, DCCP, SCTP
if desired.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/in.h | 2 | ||||
| -rw-r--r-- | include/net/inet_sock.h | 4 | ||||
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 14 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 3 |
4 files changed, 21 insertions, 2 deletions
diff --git a/include/linux/in.h b/include/linux/in.h index b615649db12..583c76f9c30 100644 --- a/include/linux/in.h +++ b/include/linux/in.h @@ -84,6 +84,8 @@ struct in_addr { #define IP_ORIGDSTADDR 20 #define IP_RECVORIGDSTADDR IP_ORIGDSTADDR +#define IP_MINTTL 21 + /* IP_MTU_DISCOVER values */ #define IP_PMTUDISC_DONT 0 /* Never send DF frames */ #define IP_PMTUDISC_WANT 1 /* Use per route hints */ diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index bd4c53f75ac..83fd34437cf 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -122,10 +122,12 @@ struct inet_sock { __be32 inet_saddr; __s16 uc_ttl; __u16 cmsg_flags; - struct ip_options *opt; __be16 inet_sport; __u16 inet_id; + + struct ip_options *opt; __u8 tos; + __u8 min_ttl; __u8 mc_ttl; __u8 pmtudisc; __u8 recverr:1, diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index cafad9baff0..644dc43a55d 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -451,7 +451,8 @@ static int do_ip_setsockopt(struct sock *sk, int level, (1<<IP_TTL) | (1<<IP_HDRINCL) | (1<<IP_MTU_DISCOVER) | (1<<IP_RECVERR) | (1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) | - (1<<IP_PASSSEC) | (1<<IP_TRANSPARENT))) || + (1<<IP_PASSSEC) | (1<<IP_TRANSPARENT) | + (1<<IP_MINTTL))) || optname == IP_MULTICAST_TTL || optname == IP_MULTICAST_ALL || optname == IP_MULTICAST_LOOP || @@ -936,6 +937,14 @@ mc_msf_out: inet->transparent = !!val; break; + case IP_MINTTL: + if (optlen < 1) + goto e_inval; + if (val < 0 || val > 255) + goto e_inval; + inet->min_ttl = val; + break; + default: err = -ENOPROTOOPT; break; @@ -1198,6 +1207,9 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname, case IP_TRANSPARENT: val = inet->transparent; break; + case IP_MINTTL: + val = inet->min_ttl; + break; default: release_sock(sk); return -ENOPROTOOPT; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 65b8ebfd078..382f667238e 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1649,6 +1649,9 @@ int tcp_v4_rcv(struct sk_buff *skb) if (!sk) goto no_tcp_socket; + if (iph->ttl < inet_sk(sk)->min_ttl) + goto discard_and_relse; + process: if (sk->sk_state == TCP_TIME_WAIT) goto do_time_wait; |