Skip to content

Commit

Permalink
nexthop: Add support for IPv4 nexthops
Browse files Browse the repository at this point in the history 
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: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
@dsahern @davem330
dsahern authored and davem330 committed May 29, 2019
1 parent ab84be7 commit 597cfe4
Show file tree
Hide file tree
Showing 2 changed files with 213 additions and 0 deletions.
5 changes: 5 additions & 0 deletions include/net/nexthop.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,10 @@ struct nh_config {
int nh_ifindex;
struct net_device *dev;

union {
__be32 ipv4;
} gw;

u32 nlflags;
struct nl_info nlinfo;
};
Expand All @@ -42,6 +46,7 @@ struct nh_info {

union {
struct fib_nh_common fib_nhc;
struct fib_nh fib_nh;
};
};

Expand Down
208 changes: 208 additions & 0 deletions net/ipv4/nexthop.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 },
Expand All @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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:
Expand All @@ -132,13 +180,21 @@ static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh,

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
* are mutually exclusive
*/
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;
}

Expand Down Expand Up @@ -169,6 +225,15 @@ static void nexthop_notify(int event, struct nexthop *nh, struct nl_info *info)
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)
{
Expand All @@ -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);
Expand Down Expand Up @@ -244,6 +310,24 @@ static int insert_nexthop(struct net *net, struct nexthop *new_nh,
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)
{
Expand All @@ -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)
{
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -683,16 +837,68 @@ static int rtm_dump_nexthop(struct sk_buff *skb, struct netlink_callback *cb)
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;
}
Expand All @@ -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,
Expand Down

0 comments on commit 597cfe4

Please sign in to comment.