ip_tunnel: Allow policy-based routing through tunnels

This feature allows the administrator to set an fwmark for
packets traversing a tunnel.  This allows the use of independent
routing tables for tunneled packets without the use of iptables.

There is no concept of per-packet routing decisions through IPv4
tunnels, so this implementation does not need to work with
per-packet route lookups as the v6 implementation may
(with IP6_TNL_F_USE_ORIG_FWMARK).

Further, since the v4 tunnel ioctls share datastructures
(which can not be trivially modified) with the kernel's internal
tunnel configuration structures, the mark attribute must be stored
in the tunnel structure itself and passed as a parameter when
creating or changing tunnel attributes.

Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 5 deletions

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 8b14f1404c8f..40977413fd48 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -471,7 +471,8 @@ static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
 }
 
 static void vti_netlink_parms(struct nlattr *data[],
-			      struct ip_tunnel_parm *parms)
+			      struct ip_tunnel_parm *parms,
+			      __u32 *fwmark)
 {
 	memset(parms, 0, sizeof(*parms));
 
@@ -497,24 +498,29 @@ static void vti_netlink_parms(struct nlattr *data[],
 	if (data[IFLA_VTI_REMOTE])
 		parms->iph.daddr = nla_get_in_addr(data[IFLA_VTI_REMOTE]);
 
+	if (data[IFLA_VTI_FWMARK])
+		*fwmark = nla_get_u32(data[IFLA_VTI_FWMARK]);
 }
 
 static int vti_newlink(struct net *src_net, struct net_device *dev,
 		       struct nlattr *tb[], struct nlattr *data[])
 {
 	struct ip_tunnel_parm parms;
+	__u32 fwmark = 0;
 
-	vti_netlink_parms(data, &parms);
-	return ip_tunnel_newlink(dev, tb, &parms);
+	vti_netlink_parms(data, &parms, &fwmark);
+	return ip_tunnel_newlink(dev, tb, &parms, fwmark);
 }
 
 static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
 			  struct nlattr *data[])
 {
+	struct ip_tunnel *t = netdev_priv(dev);
+	__u32 fwmark = t->fwmark;
 	struct ip_tunnel_parm p;
 
-	vti_netlink_parms(data, &p);
-	return ip_tunnel_changelink(dev, tb, &p);
+	vti_netlink_parms(data, &p, &fwmark);
+	return ip_tunnel_changelink(dev, tb, &p, fwmark);
 }
 
 static size_t vti_get_size(const struct net_device *dev)
@@ -530,6 +536,8 @@ static size_t vti_get_size(const struct net_device *dev)
 		nla_total_size(4) +
 		/* IFLA_VTI_REMOTE */
 		nla_total_size(4) +
+		/* IFLA_VTI_FWMARK */
+		nla_total_size(4) +
 		0;
 }
 
@@ -543,6 +551,7 @@ static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
 	nla_put_in_addr(skb, IFLA_VTI_LOCAL, p->iph.saddr);
 	nla_put_in_addr(skb, IFLA_VTI_REMOTE, p->iph.daddr);
+	nla_put_u32(skb, IFLA_VTI_FWMARK, t->fwmark);
 
 	return 0;
 }
@@ -553,6 +562,7 @@ static const struct nla_policy vti_policy[IFLA_VTI_MAX + 1] = {
 	[IFLA_VTI_OKEY]		= { .type = NLA_U32 },
 	[IFLA_VTI_LOCAL]	= { .len = FIELD_SIZEOF(struct iphdr, saddr) },
 	[IFLA_VTI_REMOTE]	= { .len = FIELD_SIZEOF(struct iphdr, daddr) },
+	[IFLA_VTI_FWMARK]	= { .type = NLA_U32 },
 };
 
 static struct rtnl_link_ops vti_link_ops __read_mostly = {