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authorStephen Hemminger <shemminger@vyatta.com>2010-01-11 16:28:01 -0800
committerDavid S. Miller <davem@davemloft.net>2010-01-11 16:28:01 -0800
commitd218d11133d888f9745802146a50255a4781d37a (patch)
tree3b4b163238e19c48f37f3d8a77eb27f3a18691a0 /net
parentc8e000604bce02a87742240a9b716a0f1b680c0b (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>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/ip_sockglue.c14
-rw-r--r--net/ipv4/tcp_ipv4.c3
2 files changed, 16 insertions, 1 deletions
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;