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authorThomas Graf <tgraf@suug.ch>2012-06-12 00:44:01 +0000
committerDavid S. Miller <davem@davemloft.net>2012-06-12 15:25:46 -0700
commitd0daebc3d622f95db181601cb0c4a0781f74f758 (patch)
treecbce3159c160d49675dba0d720d186be7f0d79d3 /net
parent0440507bbc44149e63bbfb9df730ba3820371904 (diff)
ipv4: Add interface option to enable routing of 127.0.0.0/8
Routing of 127/8 is tradtionally forbidden, we consider packets from that address block martian when routing and do not process corresponding ARP requests. This is a sane default but renders a huge address space practically unuseable. The RFC states that no address within the 127/8 block should ever appear on any network anywhere but it does not forbid the use of such addresses outside of the loopback device in particular. For example to address a pool of virtual guests behind a load balancer. This patch adds a new interface option 'route_localnet' enabling routing of the 127/8 address block and processing of ARP requests on a specific interface. Note that for the feature to work, the default local route covering 127/8 dev lo needs to be removed. Example: $ sysctl -w net.ipv4.conf.eth0.route_localnet=1 $ ip route del 127.0.0.0/8 dev lo table local $ ip addr add 127.1.0.1/16 dev eth0 $ ip route flush cache V2: Fix invalid check to auto flush cache (thanks davem) Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/arp.c3
-rw-r--r--net/ipv4/devinet.c5
-rw-r--r--net/ipv4/route.c30
3 files changed, 27 insertions, 11 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index cda37be02f8d..2e560f0c757d 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -790,7 +790,8 @@ static int arp_process(struct sk_buff *skb)
* Check for bad requests for 127.x.x.x and requests for multicast
* addresses. If this is one such, delete it.
*/
- if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
+ if (ipv4_is_multicast(tip) ||
+ (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
goto out;
/*
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 10e15a144e95..44bf82e3aef7 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1500,7 +1500,8 @@ static int devinet_conf_proc(ctl_table *ctl, int write,
if (cnf == net->ipv4.devconf_dflt)
devinet_copy_dflt_conf(net, i);
- if (i == IPV4_DEVCONF_ACCEPT_LOCAL - 1)
+ if (i == IPV4_DEVCONF_ACCEPT_LOCAL - 1 ||
+ i == IPV4_DEVCONF_ROUTE_LOCALNET - 1)
if ((new_value == 0) && (old_value != 0))
rt_cache_flush(net, 0);
}
@@ -1617,6 +1618,8 @@ static struct devinet_sysctl_table {
"force_igmp_version"),
DEVINET_SYSCTL_FLUSHING_ENTRY(PROMOTE_SECONDARIES,
"promote_secondaries"),
+ DEVINET_SYSCTL_FLUSHING_ENTRY(ROUTE_LOCALNET,
+ "route_localnet"),
},
};
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 842510d50453..655506af47ca 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1960,9 +1960,13 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
return -EINVAL;
if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
- ipv4_is_loopback(saddr) || skb->protocol != htons(ETH_P_IP))
+ skb->protocol != htons(ETH_P_IP))
goto e_inval;
+ if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
+ if (ipv4_is_loopback(saddr))
+ goto e_inval;
+
if (ipv4_is_zeronet(saddr)) {
if (!ipv4_is_local_multicast(daddr))
goto e_inval;
@@ -2203,8 +2207,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
by fib_lookup.
*/
- if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
- ipv4_is_loopback(saddr))
+ if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
goto martian_source;
if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
@@ -2216,9 +2219,17 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
if (ipv4_is_zeronet(saddr))
goto martian_source;
- if (ipv4_is_zeronet(daddr) || ipv4_is_loopback(daddr))
+ if (ipv4_is_zeronet(daddr))
goto martian_destination;
+ if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev))) {
+ if (ipv4_is_loopback(daddr))
+ goto martian_destination;
+
+ if (ipv4_is_loopback(saddr))
+ goto martian_source;
+ }
+
/*
* Now we are ready to route packet.
*/
@@ -2457,9 +2468,14 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
u16 type = res->type;
struct rtable *rth;
- if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
+ in_dev = __in_dev_get_rcu(dev_out);
+ if (!in_dev)
return ERR_PTR(-EINVAL);
+ if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
+ if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
+ return ERR_PTR(-EINVAL);
+
if (ipv4_is_lbcast(fl4->daddr))
type = RTN_BROADCAST;
else if (ipv4_is_multicast(fl4->daddr))
@@ -2470,10 +2486,6 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
if (dev_out->flags & IFF_LOOPBACK)
flags |= RTCF_LOCAL;
- in_dev = __in_dev_get_rcu(dev_out);
- if (!in_dev)
- return ERR_PTR(-EINVAL);
-
if (type == RTN_BROADCAST) {
flags |= RTCF_BROADCAST | RTCF_LOCAL;
fi = NULL;