[PATCH net-next] vrf: Add ip rules at vrf device create

[David Ahern <dsa@cumulusnetworks.com>]

VRFs require ip rules for route lookups to work properly. Currently
creating a VRF means instantiating a device and then adding the 4 ip
and ip6 rules:

    ip link add vrf-${VRF} type vrf table ${TBID}
    ip ru add oif vrf-${VRF} table ${TBID}
    ip ru add iif vrf-${VRF} table ${TBID}
    ip -6 ru add oif vrf-${VRF} table $TBID
    ip -6 ru add iif vrf-${VRF} table $TBID

Since the table is required when the vrf device is created the rules can
be inserted automatically lightening the overhead and improving the
user experience.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
 drivers/net/vrf.c       | 120 +++++++++++++++++++++++++++++++++++++++++++++++-
 include/net/fib_rules.h |   3 ++
 net/core/fib_rules.c    |   6 ++-
 3 files changed, 126 insertions(+), 3 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 56abdf224d35..5781b77d4c3f 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -36,6 +36,7 @@
 #include <net/route.h>
 #include <net/addrconf.h>
 #include <net/l3mdev.h>
+#include <net/fib_rules.h>
 
 #define RT_FL_TOS(oldflp4) \
 	((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
@@ -50,6 +51,7 @@ struct net_vrf {
 	struct rtable           *rth;
 	struct rt6_info		*rt6;
 	u32                     tb_id;
+	u32                     pref;
 };
 
 struct pcpu_dstats {
@@ -809,6 +811,112 @@ static const struct ethtool_ops vrf_ethtool_ops = {
 	.get_drvinfo	= vrf_get_drvinfo,
 };
 
+static inline size_t vrf_fib_rule_nl_size(bool have_pref)
+{
+	size_t sz;
+
+	sz = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
+			 + nla_total_size(IFNAMSIZ) /* FRA_{I,O}IFNAME */
+			 + nla_total_size(4); /* FRA_TABLE, u32 */
+
+	if (have_pref)
+		sz += nla_total_size(4); /* FRA_PRIORITY, u32 */
+
+	return sz;
+}
+
+static int vrf_fib_rule(struct net_device *dev, __u8 family, int if_type,
+			bool add_it)
+{
+	struct net_vrf *vrf = netdev_priv(dev);
+	struct fib_rule_hdr *frh;
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+	int err;
+
+	skb = nlmsg_new(vrf_fib_rule_nl_size(!!vrf->pref), GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	nlh = nlmsg_put(skb, 0, 0, 0, sizeof(*frh), 0);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	frh = nlmsg_data(nlh);
+	memset(frh, 0, sizeof(*frh));
+	frh->family = family;
+	frh->action = FR_ACT_TO_TBL;
+
+	if (nla_put_u32(skb, FRA_TABLE, vrf->tb_id))
+		goto nla_put_failure;
+
+	if (nla_put_string(skb, if_type, dev->name))
+		goto nla_put_failure;
+
+	if (vrf->pref) {
+		if (nla_put_u32(skb, FRA_PRIORITY, vrf->pref))
+			goto nla_put_failure;
+	}
+
+	nlmsg_end(skb, nlh);
+
+	/* fib_nl_{new,del}rule handling looks for net from skb->sk */
+	skb->sk = dev_net(dev)->rtnl;
+	if (add_it) {
+		err = fib_nl_newrule(skb, nlh);
+	} else {
+		err = fib_nl_delrule(skb, nlh);
+		if (err == -ENOENT)
+			err = 0;
+	}
+
+	kfree_skb(skb);
+
+	return err;
+
+nla_put_failure:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static void vrf_del_fib_rules(struct net_device *dev)
+{
+	if (vrf_fib_rule(dev, AF_INET,  FRA_IIFNAME, 0) ||
+	    vrf_fib_rule(dev, AF_INET,  FRA_OIFNAME, 0) ||
+	    vrf_fib_rule(dev, AF_INET6, FRA_IIFNAME, 0) ||
+	    vrf_fib_rule(dev, AF_INET6, FRA_OIFNAME, 0)) {
+		netdev_err(dev, "Failed to delete FIB rules for %s\n",
+			   dev->name);
+	}
+}
+
+static int vrf_add_fib_rules(struct net_device *dev)
+{
+	int err;
+
+	err = vrf_fib_rule(dev, AF_INET,  FRA_IIFNAME, 1);
+	if (err < 0)
+		goto out_err;
+
+	err = vrf_fib_rule(dev, AF_INET,  FRA_OIFNAME, 1);
+	if (err < 0)
+		goto out_err;
+
+	err = vrf_fib_rule(dev, AF_INET6, FRA_IIFNAME, 1);
+	if (err < 0)
+		goto out_err;
+
+	err = vrf_fib_rule(dev, AF_INET6, FRA_OIFNAME, 1);
+	if (err < 0)
+		goto out_err;
+
+	return 0;
+out_err:
+	netdev_err(dev, "Failed to add FIB rules for %s\n", dev->name);
+	vrf_del_fib_rules(dev);
+	return err;
+}
+
 static void vrf_setup(struct net_device *dev)
 {
 	ether_setup(dev);
@@ -842,6 +950,7 @@ static int vrf_validate(struct nlattr *tb[], struct nlattr *data[])
 
 static void vrf_dellink(struct net_device *dev, struct list_head *head)
 {
+	vrf_del_fib_rules(dev);
 	unregister_netdevice_queue(dev, head);
 }
 
@@ -849,6 +958,7 @@ static int vrf_newlink(struct net *src_net, struct net_device *dev,
 		       struct nlattr *tb[], struct nlattr *data[])
 {
 	struct net_vrf *vrf = netdev_priv(dev);
+	int err;
 
 	if (!data || !data[IFLA_VRF_TABLE])
 		return -EINVAL;
@@ -857,7 +967,15 @@ static int vrf_newlink(struct net *src_net, struct net_device *dev,
 
 	dev->priv_flags |= IFF_L3MDEV_MASTER;
 
-	return register_netdevice(dev);
+	err = register_netdevice(dev);
+	if (err)
+		goto out;
+
+	err = vrf_add_fib_rules(dev);
+	if (err)
+		unregister_netdevice(dev);
+out:
+	return err;
 }
 
 static size_t vrf_nl_getsize(const struct net_device *dev)
diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 59160de702b6..0b76f81345c9 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -117,4 +117,7 @@ int fib_rules_lookup(struct fib_rules_ops *, struct flowi *, int flags,
 		     struct fib_lookup_arg *);
 int fib_default_rule_add(struct fib_rules_ops *, u32 pref, u32 table,
 			 u32 flags);
+
+int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh);
+int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh);
 #endif
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 365de66436ac..a5068c558bfb 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -265,7 +265,7 @@ static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 	return err;
 }
 
-static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh)
+int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
@@ -424,8 +424,9 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh)
 	rules_ops_put(ops);
 	return err;
 }
+EXPORT_SYMBOL_GPL(fib_nl_newrule);
 
-static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh)
+int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
@@ -536,6 +537,7 @@ static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh)
 	rules_ops_put(ops);
 	return err;
 }
+EXPORT_SYMBOL_GPL(fib_nl_delrule);
 
 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 					 struct fib_rule *rule)
-- 
1.9.1