[PATCH net-next 3/3] net, neigh: Reject creating NUD_PERMANENT with NTF_MANAGED entries
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2021-10-13 13:21:56
Also in:
bpf
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
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