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mpls: Hold dev refcnt for mpls_nh.
MPLS uses RTNL 1) to guarantee the lifetime of struct mpls_nh.nh_dev 2) to protect net->mpls.platform_label , but neither actually requires RTNL. If we do not call dev_put() in find_outdev() and call it just before freeing struct mpls_route, we can drop RTNL for 1). Let's hold the refcnt of mpls_nh.nh_dev and track it with netdevice_tracker. Two notable changes: If mpls_nh_build_multi() fails to set up a neighbour, we need to call netdev_put() for successfully created neighbours in mpls_rt_free_rcu(), so the number of neighbours (rt->rt_nhn) is now updated in each iteration. When a dev is unregistered, mpls_ifdown() clones mpls_route and replaces it with the clone, so the clone requires extra netdev_hold(). Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Guillaume Nault <gnault@redhat.com> Link: https://patch.msgid.link/20251029173344.2934622-3-kuniyu@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima
committed by
Jakub Kicinski
Jakub Kicinski
parent
2214ca1ff6
commit
f0914b8436
@@ -530,10 +530,23 @@ static struct mpls_route *mpls_rt_alloc(u8 num_nh, u8 max_alen, u8 max_labels)
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return rt;
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}
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static void mpls_rt_free_rcu(struct rcu_head *head)
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{
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struct mpls_route *rt;
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rt = container_of(head, struct mpls_route, rt_rcu);
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change_nexthops(rt) {
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netdev_put(nh->nh_dev, &nh->nh_dev_tracker);
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} endfor_nexthops(rt);
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kfree(rt);
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}
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static void mpls_rt_free(struct mpls_route *rt)
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{
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if (rt)
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kfree_rcu(rt, rt_rcu);
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call_rcu(&rt->rt_rcu, mpls_rt_free_rcu);
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}
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static void mpls_notify_route(struct net *net, unsigned index,
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@@ -587,6 +600,7 @@ static unsigned find_free_label(struct net *net)
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#if IS_ENABLED(CONFIG_INET)
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static struct net_device *inet_fib_lookup_dev(struct net *net,
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struct mpls_nh *nh,
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const void *addr)
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{
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struct net_device *dev;
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@@ -599,14 +613,14 @@ static struct net_device *inet_fib_lookup_dev(struct net *net,
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return ERR_CAST(rt);
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dev = rt->dst.dev;
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dev_hold(dev);
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netdev_hold(dev, &nh->nh_dev_tracker, GFP_KERNEL);
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ip_rt_put(rt);
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return dev;
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}
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#else
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static struct net_device *inet_fib_lookup_dev(struct net *net,
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struct mpls_nh *nh,
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const void *addr)
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{
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return ERR_PTR(-EAFNOSUPPORT);
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@@ -615,6 +629,7 @@ static struct net_device *inet_fib_lookup_dev(struct net *net,
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#if IS_ENABLED(CONFIG_IPV6)
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static struct net_device *inet6_fib_lookup_dev(struct net *net,
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struct mpls_nh *nh,
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const void *addr)
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{
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struct net_device *dev;
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@@ -631,13 +646,14 @@ static struct net_device *inet6_fib_lookup_dev(struct net *net,
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return ERR_CAST(dst);
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dev = dst->dev;
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dev_hold(dev);
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netdev_hold(dev, &nh->nh_dev_tracker, GFP_KERNEL);
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dst_release(dst);
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return dev;
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}
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#else
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static struct net_device *inet6_fib_lookup_dev(struct net *net,
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struct mpls_nh *nh,
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const void *addr)
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{
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return ERR_PTR(-EAFNOSUPPORT);
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@@ -653,16 +669,17 @@ static struct net_device *find_outdev(struct net *net,
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if (!oif) {
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switch (nh->nh_via_table) {
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case NEIGH_ARP_TABLE:
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dev = inet_fib_lookup_dev(net, mpls_nh_via(rt, nh));
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dev = inet_fib_lookup_dev(net, nh, mpls_nh_via(rt, nh));
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break;
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case NEIGH_ND_TABLE:
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dev = inet6_fib_lookup_dev(net, mpls_nh_via(rt, nh));
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dev = inet6_fib_lookup_dev(net, nh, mpls_nh_via(rt, nh));
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break;
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case NEIGH_LINK_TABLE:
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break;
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}
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} else {
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dev = dev_get_by_index(net, oif);
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dev = netdev_get_by_index(net, oif,
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&nh->nh_dev_tracker, GFP_KERNEL);
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}
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if (!dev)
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@@ -671,8 +688,7 @@ static struct net_device *find_outdev(struct net *net,
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if (IS_ERR(dev))
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return dev;
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/* The caller is holding rtnl anyways, so release the dev reference */
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dev_put(dev);
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nh->nh_dev = dev;
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return dev;
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}
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@@ -686,20 +702,17 @@ static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
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dev = find_outdev(net, rt, nh, oif);
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if (IS_ERR(dev)) {
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err = PTR_ERR(dev);
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dev = NULL;
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goto errout;
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}
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/* Ensure this is a supported device */
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err = -EINVAL;
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if (!mpls_dev_get(dev))
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goto errout;
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goto errout_put;
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if ((nh->nh_via_table == NEIGH_LINK_TABLE) &&
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(dev->addr_len != nh->nh_via_alen))
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goto errout;
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nh->nh_dev = dev;
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goto errout_put;
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if (!(dev->flags & IFF_UP)) {
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nh->nh_flags |= RTNH_F_DEAD;
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@@ -713,6 +726,9 @@ static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
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return 0;
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errout_put:
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netdev_put(nh->nh_dev, &nh->nh_dev_tracker);
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nh->nh_dev = NULL;
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errout:
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return err;
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}
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@@ -890,7 +906,8 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
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struct nlattr *nla_via, *nla_newdst;
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int remaining = cfg->rc_mp_len;
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int err = 0;
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u8 nhs = 0;
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rt->rt_nhn = 0;
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change_nexthops(rt) {
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int attrlen;
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@@ -926,11 +943,9 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
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rt->rt_nhn_alive--;
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rtnh = rtnh_next(rtnh, &remaining);
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nhs++;
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rt->rt_nhn++;
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} endfor_nexthops(rt);
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rt->rt_nhn = nhs;
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return 0;
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errout:
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@@ -1523,8 +1538,12 @@ static int mpls_ifdown(struct net_device *dev, int event)
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change_nexthops(rt) {
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unsigned int nh_flags = nh->nh_flags;
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if (nh->nh_dev != dev)
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if (nh->nh_dev != dev) {
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if (nh_del)
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netdev_hold(nh->nh_dev, &nh->nh_dev_tracker,
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GFP_KERNEL);
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goto next;
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}
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switch (event) {
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case NETDEV_DOWN:
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@@ -2518,10 +2537,13 @@ static int resize_platform_label_table(struct net *net, size_t limit)
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/* In case the predefined labels need to be populated */
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if (limit > MPLS_LABEL_IPV4NULL) {
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struct net_device *lo = net->loopback_dev;
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rt0 = mpls_rt_alloc(1, lo->addr_len, 0);
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if (IS_ERR(rt0))
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goto nort0;
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rt0->rt_nh->nh_dev = lo;
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netdev_hold(lo, &rt0->rt_nh->nh_dev_tracker, GFP_KERNEL);
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rt0->rt_protocol = RTPROT_KERNEL;
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rt0->rt_payload_type = MPT_IPV4;
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rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
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@@ -2532,10 +2554,13 @@ static int resize_platform_label_table(struct net *net, size_t limit)
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}
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if (limit > MPLS_LABEL_IPV6NULL) {
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struct net_device *lo = net->loopback_dev;
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rt2 = mpls_rt_alloc(1, lo->addr_len, 0);
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if (IS_ERR(rt2))
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goto nort2;
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rt2->rt_nh->nh_dev = lo;
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netdev_hold(lo, &rt2->rt_nh->nh_dev_tracker, GFP_KERNEL);
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rt2->rt_protocol = RTPROT_KERNEL;
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rt2->rt_payload_type = MPT_IPV6;
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rt2->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
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@@ -88,6 +88,7 @@ enum mpls_payload_type {
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struct mpls_nh { /* next hop label forwarding entry */
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struct net_device *nh_dev;
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netdevice_tracker nh_dev_tracker;
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/* nh_flags is accessed under RCU in the packet path; it is
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* modified handling netdev events with rtnl lock held
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