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tcp: Generalized TTL Security Mechanism

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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>
This commit is contained in:
Stephen Hemminger
2010-01-11 16:28:01 -08:00
committed by David S. Miller
parent c8e000604b
commit d218d11133
4 changed files with 21 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
net/ipv4/ip_sockglue.c
View File

@@ -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;