The combination of NUD_PERMANENT + NTF_MANAGED is not supported and does
not make sense either given the former indicates a static/fixed neighbor
entry whereas the latter a dynamically resolved one. While it is possible
to transition from one over to the other, we should however reject such
creation attempts.
Fixes: 7482e3841d52 ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries")
Suggested-by: David Ahern <dsahern@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
net/core/neighbour.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 922b9ed0fe76..47931c8be04b 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1999,15 +1999,20 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh,
neigh = neigh_lookup(tbl, dst, dev);
if (neigh == NULL) {
- bool exempt_from_gc;
+ bool ndm_permanent = ndm->ndm_state & NUD_PERMANENT;
+ bool exempt_from_gc = ndm_permanent ||
+ ndm_flags & NTF_EXT_LEARNED;
if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
err = -ENOENT;
goto out;
}
+ if (ndm_permanent && (ndm_flags & NTF_MANAGED)) {
+ NL_SET_ERR_MSG(extack, "Invalid NTF_* flag for permanent entry");
+ err = -EINVAL;
+ goto out;
+ }
- exempt_from_gc = ndm->ndm_state & NUD_PERMANENT ||
- ndm_flags & NTF_EXT_LEARNED;
neigh = ___neigh_create(tbl, dst, dev,
ndm_flags &
(NTF_EXT_LEARNED | NTF_MANAGED),
--
2.27.0
