From 30fc7efa38f21afa48b0be6bf2053e4c10ae2c78 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 13 Oct 2021 15:21:40 +0200 Subject: net, neigh: Reject creating NUD_PERMANENT with NTF_MANAGED entries 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 Signed-off-by: Daniel Borkmann Reviewed-by: David Ahern Signed-off-by: Jakub Kicinski --- 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), -- cgit v1.2.3