[PATCH] Implement IP_EVIL socket option (RFC 3514)

From: Martin Lucina
Date: Sun Apr 01 2012 - 09:03:26 EST


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@xxxxxxxxxx>
---
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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/