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authorThomas Graf <tgraf@suug.ch>2012-06-12 04:44:01 +0400
committerDavid S. Miller <davem@davemloft.net>2012-06-13 02:25:46 +0400
commitd0daebc3d622f95db181601cb0c4a0781f74f758 (patch)
treecbce3159c160d49675dba0d720d186be7f0d79d3 /include/linux/inetdevice.h
parent0440507bbc44149e63bbfb9df730ba3820371904 (diff)
downloadlinux-d0daebc3d622f95db181601cb0c4a0781f74f758.tar.xz
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 'include/linux/inetdevice.h')
-rw-r--r--include/linux/inetdevice.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 597f4a9f3240..67f9ddacb70c 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -38,6 +38,7 @@ enum
IPV4_DEVCONF_ACCEPT_LOCAL,
IPV4_DEVCONF_SRC_VMARK,
IPV4_DEVCONF_PROXY_ARP_PVLAN,
+ IPV4_DEVCONF_ROUTE_LOCALNET,
__IPV4_DEVCONF_MAX
};
@@ -131,6 +132,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
#define IN_DEV_PROMOTE_SECONDARIES(in_dev) \
IN_DEV_ORCONF((in_dev), \
PROMOTE_SECONDARIES)
+#define IN_DEV_ROUTE_LOCALNET(in_dev) IN_DEV_ORCONF(in_dev, ROUTE_LOCALNET)
#define IN_DEV_RX_REDIRECTS(in_dev) \
((IN_DEV_FORWARD(in_dev) && \