net: provide a sysctl raw_l3mdev_accept for raw socket lookup with VRFs

Add a sysctl raw_l3mdev_accept to control raw socket lookup in a manner
similar to use of tcp_l3mdev_accept for stream and of udp_l3mdev_accept
for datagram sockets. Have this default to enabled for reasons of
backwards compatibility. This is so as to specify the output device
with cmsg and IP_PKTINFO, but using a socket not bound to the
corresponding VRF. This allows e.g. older ping implementations to be
run with specifying the device but without executing it in the VRF.
If the option is disabled, packets received in a VRF context are only
handled by a raw socket bound to the VRF, and correspondingly packets
in the default VRF are only handled by a socket not bound to any VRF.

Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 32b21571adfe..aa9e6a331679 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -370,6 +370,7 @@ tcp_l3mdev_accept - BOOLEAN
 	derived from the listen socket to be bound to the L3 domain in
 	which the packets originated. Only valid when the kernel was
 	compiled with CONFIG_NET_L3_MASTER_DEV.
+        Default: 0 (disabled)
 
 tcp_low_latency - BOOLEAN
 	This is a legacy option, it has no effect anymore.
@@ -773,6 +774,7 @@ udp_l3mdev_accept - BOOLEAN
 	being received regardless of the L3 domain in which they
 	originated. Only valid when the kernel was compiled with
 	CONFIG_NET_L3_MASTER_DEV.
+        Default: 0 (disabled)
 
 udp_mem - vector of 3 INTEGERs: min, pressure, max
 	Number of pages allowed for queueing by all UDP sockets.
@@ -799,6 +801,16 @@ udp_wmem_min - INTEGER
 	total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
 	Default: 4K
 
+RAW variables:
+
+raw_l3mdev_accept - BOOLEAN
+	Enabling this option allows a "global" bound socket to work
+	across L3 master domains (e.g., VRFs) with packets capable of
+	being received regardless of the L3 domain in which they
+	originated. Only valid when the kernel was compiled with
+	CONFIG_NET_L3_MASTER_DEV.
+	Default: 1 (enabled)
+
 CIPSOv4 Variables:
 
 cipso_cache_enable - BOOLEAN