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Commit f7fd0720 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Greg Kroah-Hartman
Browse files

net, neigh: Fix NTF_EXT_LEARNED in combination with NTF_USE 



[ Upstream commit e4400bbf5b15750e1b59bf4722d18d99be60c69f ]

The NTF_EXT_LEARNED neigh flag is usually propagated back to user space
upon dump of the neighbor table. However, when used in combination with
NTF_USE flag this is not the case despite exempting the entry from the
garbage collector. This results in inconsistent state since entries are
typically marked in neigh->flags with NTF_EXT_LEARNED, but here they are
not. Fix it by propagating the creation flag to ___neigh_create().

Before fix:

  # ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
  # ./ip/ip n
  192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
  [...]

After fix:

  # ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
  # ./ip/ip n
  192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a extern_learn REACHABLE
  [...]

Fixes: 9ce33e46 ("neighbour: support for NTF_EXT_LEARNED flag")
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarRoopa Prabhu <roopa@nvidia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 9498f527

net/core/neighbour.c

+14 −12
Original line number Diff line number Diff line
@@ -380,7 +380,7 @@ EXPORT_SYMBOL(neigh_ifdown); 


static struct neighbour *neigh_alloc(struct neigh_table *tbl,

				     struct net_device *dev,

				     bool exempt_from_gc)

				     u8 flags, bool exempt_from_gc)

{

	struct neighbour *n = NULL;

	unsigned long now = jiffies;
@@ -413,6 +413,7 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl, 
	n->updated	  = n->used = now;

	n->nud_state	  = NUD_NONE;

	n->output	  = neigh_blackhole;

	n->flags	  = flags;

	seqlock_init(&n->hh.hh_lock);

	n->parms	  = neigh_parms_clone(&tbl->parms);

	timer_setup(&n->timer, neigh_timer_handler, 0);
@@ -576,19 +577,18 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net, 
}

EXPORT_SYMBOL(neigh_lookup_nodev);



static struct neighbour *___neigh_create(struct neigh_table *tbl,

					 const void *pkey,

					 struct net_device *dev,

static struct neighbour *

___neigh_create(struct neigh_table *tbl, const void *pkey,

		struct net_device *dev, u8 flags,

		bool exempt_from_gc, bool want_ref)

{

	struct neighbour *n1, *rc, *n = neigh_alloc(tbl, dev, exempt_from_gc);

	u32 hash_val;

	unsigned int key_len = tbl->key_len;

	int error;

	u32 hash_val, key_len = tbl->key_len;

	struct neighbour *n1, *rc, *n;

	struct neigh_hash_table *nht;

	int error;



	n = neigh_alloc(tbl, dev, flags, exempt_from_gc);

	trace_neigh_create(tbl, dev, pkey, n, exempt_from_gc);



	if (!n) {

		rc = ERR_PTR(-ENOBUFS);

		goto out;
@@ -675,7 +675,7 @@ static struct neighbour *___neigh_create(struct neigh_table *tbl, 
struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,

				 struct net_device *dev, bool want_ref)

{

	return ___neigh_create(tbl, pkey, dev, false, want_ref);

	return ___neigh_create(tbl, pkey, dev, 0, false, want_ref);

}

EXPORT_SYMBOL(__neigh_create);
@@ -1945,7 +1945,9 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh, 


		exempt_from_gc = ndm->ndm_state & NUD_PERMANENT ||

				 ndm->ndm_flags & NTF_EXT_LEARNED;

		neigh = ___neigh_create(tbl, dst, dev, exempt_from_gc, true);

		neigh = ___neigh_create(tbl, dst, dev,

					ndm->ndm_flags & NTF_EXT_LEARNED,

					exempt_from_gc, true);

		if (IS_ERR(neigh)) {

			err = PTR_ERR(neigh);

			goto out;