[Cerowrt-devel] Fwd: [PATCH] Implement IP_EVIL socket option (RFC 3514)

[Dave Taht]

You know, I really, really hate not having used up all the bits in the ip
header.

There is some encouraging work in the conex working group

http://datatracker.ietf.org/wg/conex/charter/

that needs this bit in order to implement at least part of their core idea.

So I think today would be a good day to commit to using up that last bit in
cerowrt.

---------- Forwarded message ----------
From: Martin Lucina <martin at lucina.net>
Date: Sun, Apr 1, 2012 at 1:53 PM
Subject: [PATCH] Implement IP_EVIL socket option (RFC 3514)
To: linux-kernel at vger.kernel.org, netdev at vger.kernel.org
Cc: Martin Lucina <martin at lucina.net>


This patch implements the IP_EVIL socket option, allowing user-space
applications to set the Security Flag in the IPv4 Header, aka "evil" bit,
as defined in RFC 3514.

Signed-off-by: Martin Lucina <martin at lucina.net>
---
 include/linux/in.h      |    1 +
 include/net/inet_sock.h |    1 +
 net/ipv4/af_inet.c      |    1 +
 net/ipv4/ip_output.c    |    2 ++
 net/ipv4/ip_sockglue.c  |    9 ++++++++-
 5 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/include/linux/in.h b/include/linux/in.h
index e0337f1..6814c0f 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -86,6 +86,7 @@ struct in_addr {

 #define IP_MINTTL       21
 #define IP_NODEFRAG     22
+#define IP_EVIL         23

 /* IP_MTU_DISCOVER values */
 #define IP_PMTUDISC_DONT               0       /* Never send DF frames */
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index ae17e13..37aaf9b 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -168,6 +168,7 @@ struct inet_sock {
                               transparent:1,
                               mc_all:1,
                               nodefrag:1;
+       __u8                    evil;
       __u8                    rcv_tos;
       int                     uc_index;
       int                     mc_index;
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 10e3751..b165dfb 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -356,6 +356,7 @@ lookup_protocol:
       inet->is_icsk = (INET_PROTOSW_ICSK & answer_flags) != 0;

       inet->nodefrag = 0;
+       inet->evil = 0; /* Don't be evil */

       if (SOCK_RAW == sock->type) {
               inet->inet_num = protocol;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4910176..c1b4b15 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -157,6 +157,8 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct
sock *sk,
               iph->frag_off = htons(IP_DF);
       else
               iph->frag_off = 0;
+       if (inet->evil)
+               iph->frag_off |= 1<<15;
       iph->ttl      = ip_select_ttl(inet, &rt->dst);
       iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
       iph->saddr    = saddr;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 2fd0fba..f26d45c 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -463,7 +463,8 @@ static int do_ip_setsockopt(struct sock *sk, int level,
                            (1<<IP_MTU_DISCOVER) | (1<<IP_RECVERR) |
                            (1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) |
                            (1<<IP_PASSSEC) | (1<<IP_TRANSPARENT) |
-                            (1<<IP_MINTTL) | (1<<IP_NODEFRAG))) ||
+                            (1<<IP_MINTTL) | (1<<IP_NODEFRAG) |
+                            (1<<IP_EVIL))) ||
           optname == IP_UNICAST_IF ||
           optname == IP_MULTICAST_TTL ||
           optname == IP_MULTICAST_ALL ||
@@ -598,6 +599,9 @@ static int do_ip_setsockopt(struct sock *sk, int level,
               }
               inet->nodefrag = val ? 1 : 0;
               break;
+       case IP_EVIL:
+               inet->evil = val ? 1 : 0;
+               break;
       case IP_MTU_DISCOVER:
               if (val < IP_PMTUDISC_DONT || val > IP_PMTUDISC_PROBE)
                       goto e_inval;
@@ -1176,6 +1180,9 @@ static int do_ip_getsockopt(struct sock *sk, int
level, int optname,
       case IP_NODEFRAG:
               val = inet->nodefrag;
               break;
+       case IP_EVIL:
+               val = inet->evil;
+               break;
       case IP_MTU_DISCOVER:
               val = inet->pmtudisc;
               break;
--
1.7.9.1

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-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net
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