Commit 597cfe4f authored by David Ahern's avatar David Ahern Committed by David S. Miller
Browse files

nexthop: Add support for IPv4 nexthops 



Add support for IPv4 nexthops. If nh_family is set to AF_INET, then
NHA_GATEWAY is expected to be an IPv4 address.

Register for netdev events to be notified of admin up/down changes as
well as deletes. A hash table is used to track nexthop per devices to
quickly convert device events to the affected nexthops.

Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ab84be7e

include/net/nexthop.h

+5 −0
Original line number Diff line number Diff line
@@ -29,6 +29,10 @@ struct nh_config { 
	int		nh_ifindex;

	struct net_device *dev;



	union {

		__be32		ipv4;

	} gw;



	u32		nlflags;

	struct nl_info	nlinfo;

};
@@ -42,6 +46,7 @@ struct nh_info { 


	union {

		struct fib_nh_common	fib_nhc;

		struct fib_nh		fib_nh;

	};

};

net/ipv4/nexthop.c

+208 −0
Original line number Diff line number Diff line
@@ -9,8 +9,12 @@ 
#include <linux/rtnetlink.h>

#include <linux/slab.h>

#include <net/nexthop.h>

#include <net/route.h>

#include <net/sock.h>



#define NH_DEV_HASHBITS  8

#define NH_DEV_HASHSIZE (1U << NH_DEV_HASHBITS)



static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {

	[NHA_UNSPEC]		= { .strict_start_type = NHA_UNSPEC + 1 },

	[NHA_ID]		= { .type = NLA_U32 },
@@ -25,12 +29,39 @@ static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = { 
	[NHA_MASTER]		= { .type = NLA_U32 },

};



static unsigned int nh_dev_hashfn(unsigned int val)

{

	unsigned int mask = NH_DEV_HASHSIZE - 1;



	return (val ^

		(val >> NH_DEV_HASHBITS) ^

		(val >> (NH_DEV_HASHBITS * 2))) & mask;

}



static void nexthop_devhash_add(struct net *net, struct nh_info *nhi)

{

	struct net_device *dev = nhi->fib_nhc.nhc_dev;

	struct hlist_head *head;

	unsigned int hash;



	WARN_ON(!dev);



	hash = nh_dev_hashfn(dev->ifindex);

	head = &net->nexthop.devhash[hash];

	hlist_add_head(&nhi->dev_hash, head);

}



void nexthop_free_rcu(struct rcu_head *head)

{

	struct nexthop *nh = container_of(head, struct nexthop, rcu);

	struct nh_info *nhi;



	nhi = rcu_dereference_raw(nh->nh_info);

	switch (nhi->family) {

	case AF_INET:

		fib_nh_release(nh->net, &nhi->fib_nh);

		break;

	}

	kfree(nhi);



	kfree(nh);
@@ -96,6 +127,7 @@ static u32 nh_find_unused_id(struct net *net) 
static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh,

			int event, u32 portid, u32 seq, unsigned int nlflags)

{

	struct fib_nh *fib_nh;

	struct nlmsghdr *nlh;

	struct nh_info *nhi;

	struct nhmsg *nhm;
@@ -120,6 +152,22 @@ static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh, 
		if (nla_put_flag(skb, NHA_BLACKHOLE))

			goto nla_put_failure;

		goto out;

	} else {

		const struct net_device *dev;



		dev = nhi->fib_nhc.nhc_dev;

		if (dev && nla_put_u32(skb, NHA_OIF, dev->ifindex))

			goto nla_put_failure;

	}



	nhm->nh_scope = nhi->fib_nhc.nhc_scope;

	switch (nhi->family) {

	case AF_INET:

		fib_nh = &nhi->fib_nh;

		if (fib_nh->fib_nh_gw_family &&

		    nla_put_u32(skb, NHA_GATEWAY, fib_nh->fib_nh_gw4))

			goto nla_put_failure;

		break;

	}



out:
@@ -132,6 +180,7 @@ nla_put_failure: 


static size_t nh_nlmsg_size(struct nexthop *nh)

{

	struct nh_info *nhi = rtnl_dereference(nh->nh_info);

	size_t sz = nla_total_size(4);    /* NHA_ID */



	/* covers NHA_BLACKHOLE since NHA_OIF and BLACKHOLE
@@ -139,6 +188,13 @@ static size_t nh_nlmsg_size(struct nexthop *nh) 
	 */

	sz += nla_total_size(4);  /* NHA_OIF */



	switch (nhi->family) {

	case AF_INET:

		if (nhi->fib_nh.fib_nh_gw_family)

			sz += nla_total_size(4);  /* NHA_GATEWAY */

		break;

	}



	return sz;

}
@@ -169,6 +225,15 @@ errout: 
		rtnl_set_sk_err(info->nl_net, RTNLGRP_NEXTHOP, err);

}



static void __remove_nexthop(struct net *net, struct nexthop *nh)

{

	struct nh_info *nhi;



	nhi = rtnl_dereference(nh->nh_info);

	if (nhi->fib_nhc.nhc_dev)

		hlist_del(&nhi->dev_hash);

}



static void remove_nexthop(struct net *net, struct nexthop *nh,

			   bool skip_fib, struct nl_info *nlinfo)

{
@@ -178,6 +243,7 @@ static void remove_nexthop(struct net *net, struct nexthop *nh, 
	if (nlinfo)

		nexthop_notify(RTM_DELNEXTHOP, nh, nlinfo);



	__remove_nexthop(net, nh);

	nh_base_seq_inc(net);



	nexthop_put(nh);
@@ -244,6 +310,24 @@ out: 
	return rc;

}



/* rtnl */

/* remove all nexthops tied to a device being deleted */

static void nexthop_flush_dev(struct net_device *dev)

{

	unsigned int hash = nh_dev_hashfn(dev->ifindex);

	struct net *net = dev_net(dev);

	struct hlist_head *head = &net->nexthop.devhash[hash];

	struct hlist_node *n;

	struct nh_info *nhi;



	hlist_for_each_entry_safe(nhi, n, head, dev_hash) {

		if (nhi->fib_nhc.nhc_dev != dev)

			continue;



		remove_nexthop(net, nhi->nh_parent, false, NULL);

	}

}



/* rtnl; called when net namespace is deleted */

static void flush_all_nexthops(struct net *net)

{
@@ -258,6 +342,38 @@ static void flush_all_nexthops(struct net *net) 
	}

}



static int nh_create_ipv4(struct net *net, struct nexthop *nh,

			  struct nh_info *nhi, struct nh_config *cfg,

			  struct netlink_ext_ack *extack)

{

	struct fib_nh *fib_nh = &nhi->fib_nh;

	struct fib_config fib_cfg = {

		.fc_oif   = cfg->nh_ifindex,

		.fc_gw4   = cfg->gw.ipv4,

		.fc_gw_family = cfg->gw.ipv4 ? AF_INET : 0,

		.fc_flags = cfg->nh_flags,

	};

	u32 tb_id = l3mdev_fib_table(cfg->dev);

	int err = -EINVAL;



	err = fib_nh_init(net, fib_nh, &fib_cfg, 1, extack);

	if (err) {

		fib_nh_release(net, fib_nh);

		goto out;

	}



	/* sets nh_dev if successful */

	err = fib_check_nh(net, fib_nh, tb_id, 0, extack);

	if (!err) {

		nh->nh_flags = fib_nh->fib_nh_flags;

		fib_info_update_nh_saddr(net, fib_nh, fib_nh->fib_nh_scope);

	} else {

		fib_nh_release(net, fib_nh);

	}

out:

	return err;

}



static struct nexthop *nexthop_create(struct net *net, struct nh_config *cfg,

				      struct netlink_ext_ack *extack)

{
@@ -287,12 +403,21 @@ static struct nexthop *nexthop_create(struct net *net, struct nh_config *cfg, 
		cfg->nh_ifindex = net->loopback_dev->ifindex;

	}



	switch (cfg->nh_family) {

	case AF_INET:

		err = nh_create_ipv4(net, nh, nhi, cfg, extack);

		break;

	}



	if (err) {

		kfree(nhi);

		kfree(nh);

		return ERR_PTR(err);

	}



	/* add the entry to the device based hash */

	nexthop_devhash_add(net, nhi);



	rcu_assign_pointer(nh->nh_info, nhi);



	return nh;
@@ -329,6 +454,7 @@ static struct nexthop *nexthop_add(struct net *net, struct nh_config *cfg, 


	err = insert_nexthop(net, nh, cfg, extack);

	if (err) {

		__remove_nexthop(net, nh);

		nexthop_put(nh);

		nh = ERR_PTR(err);

	}
@@ -360,6 +486,8 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb, 
	}



	switch (nhm->nh_family) {

	case AF_INET:

		break;

	default:

		NL_SET_ERR_MSG(extack, "Invalid address family");

		goto out;
@@ -416,6 +544,32 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb, 
		goto out;

	}



	err = -EINVAL;

	if (tb[NHA_GATEWAY]) {

		struct nlattr *gwa = tb[NHA_GATEWAY];



		switch (cfg->nh_family) {

		case AF_INET:

			if (nla_len(gwa) != sizeof(u32)) {

				NL_SET_ERR_MSG(extack, "Invalid gateway");

				goto out;

			}

			cfg->gw.ipv4 = nla_get_be32(gwa);

			break;

		default:

			NL_SET_ERR_MSG(extack,

				       "Unknown address family for gateway");

			goto out;

		}

	} else {

		/* device only nexthop (no gateway) */

		if (cfg->nh_flags & RTNH_F_ONLINK) {

			NL_SET_ERR_MSG(extack,

				       "ONLINK flag can not be set for nexthop without a gateway");

			goto out;

		}

	}



	err = 0;

out:

	return err;
@@ -683,16 +837,68 @@ out_err: 
	return err;

}



static void nexthop_sync_mtu(struct net_device *dev, u32 orig_mtu)

{

	unsigned int hash = nh_dev_hashfn(dev->ifindex);

	struct net *net = dev_net(dev);

	struct hlist_head *head = &net->nexthop.devhash[hash];

	struct hlist_node *n;

	struct nh_info *nhi;



	hlist_for_each_entry_safe(nhi, n, head, dev_hash) {

		if (nhi->fib_nhc.nhc_dev == dev) {

			if (nhi->family == AF_INET)

				fib_nhc_update_mtu(&nhi->fib_nhc, dev->mtu,

						   orig_mtu);

		}

	}

}



/* rtnl */

static int nh_netdev_event(struct notifier_block *this,

			   unsigned long event, void *ptr)

{

	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

	struct netdev_notifier_info_ext *info_ext;



	switch (event) {

	case NETDEV_DOWN:

	case NETDEV_UNREGISTER:

		nexthop_flush_dev(dev);

		break;

	case NETDEV_CHANGE:

		if (!(dev_get_flags(dev) & (IFF_RUNNING | IFF_LOWER_UP)))

			nexthop_flush_dev(dev);

		break;

	case NETDEV_CHANGEMTU:

		info_ext = ptr;

		nexthop_sync_mtu(dev, info_ext->ext.mtu);

		rt_cache_flush(dev_net(dev));

		break;

	}

	return NOTIFY_DONE;

}



static struct notifier_block nh_netdev_notifier = {

	.notifier_call = nh_netdev_event,

};



static void __net_exit nexthop_net_exit(struct net *net)

{

	rtnl_lock();

	flush_all_nexthops(net);

	rtnl_unlock();

	kfree(net->nexthop.devhash);

}



static int __net_init nexthop_net_init(struct net *net)

{

	size_t sz = sizeof(struct hlist_head) * NH_DEV_HASHSIZE;



	net->nexthop.rb_root = RB_ROOT;

	net->nexthop.devhash = kzalloc(sz, GFP_KERNEL);

	if (!net->nexthop.devhash)

		return -ENOMEM;



	return 0;

}
@@ -706,6 +912,8 @@ static int __init nexthop_init(void) 
{

	register_pernet_subsys(&nexthop_net_ops);



	register_netdevice_notifier(&nh_netdev_notifier);



	rtnl_register(PF_UNSPEC, RTM_NEWNEXTHOP, rtm_new_nexthop, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_DELNEXTHOP, rtm_del_nexthop, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_GETNEXTHOP, rtm_get_nexthop,

CRA Git | Maintained and supported by SUSTech CRA and CCSE