Merge tag 'nf-next-2023-05-18' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next

Florian Westphal says:

====================
Netfilter updates for net-next

nftables updates:

1. Allow key existence checks with maps.
   At the moment the kernel requires userspace to pass a destination
   register for the associated value, make this optional so userspace
   can query if the key exists, just like with normal sets.

2. nftables maintains a counter per set that holds the number of
   elements.  This counter gets decremented on element removal,
   but its only incremented if the set has a upper maximum value.
   Increment unconditionally, this will allow us to update the
   maximum value later on.

3. At DCCP option maching, from Jeremy Sowden.

4. use struct_size macro, from Christophe JAILLET.

Conntrack:

5. Squash holes in struct nf_conntrack_expect, also Christophe JAILLET.

6. Allow clash resolution for GRE Protocol to avoid a packet drop,
   from Faicker Mo.

Flowtable:

Simplify route logic and split large functions into smaller
chunks, from Pablo Neira Ayuso.

* tag 'nf-next-2023-05-18' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: flowtable: split IPv6 datapath in helper functions
  netfilter: flowtable: split IPv4 datapath in helper functions
  netfilter: flowtable: simplify route logic
  netfilter: conntrack: allow insertion clash of gre protocol
  netfilter: nft_set_pipapo: Use struct_size()
  netfilter: Reorder fields in 'struct nf_conntrack_expect'
  netfilter: nft_exthdr: add boolean DCCP option matching
  netfilter: nf_tables: always increment set element count
  netfilter: nf_tables: relax set/map validation checks
====================

Link: https://lore.kernel.org/r/20230518100759.84858-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 15 insertions, 8 deletions

diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index 03ef4fdaa460..29ac48cdd6db 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -19,6 +19,7 @@ struct nft_lookup {
 	struct nft_set			*set;
 	u8				sreg;
 	u8				dreg;
+	bool				dreg_set;
 	bool				invert;
 	struct nft_set_binding		binding;
 };
@@ -75,7 +76,7 @@ void nft_lookup_eval(const struct nft_expr *expr,
 	}
 
 	if (ext) {
-		if (set->flags & NFT_SET_MAP)
+		if (priv->dreg_set)
 			nft_data_copy(&regs->data[priv->dreg],
 				      nft_set_ext_data(ext), set->dlen);
 
@@ -122,11 +123,8 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
 		if (flags & ~NFT_LOOKUP_F_INV)
 			return -EINVAL;
 
-		if (flags & NFT_LOOKUP_F_INV) {
-			if (set->flags & NFT_SET_MAP)
-				return -EINVAL;
+		if (flags & NFT_LOOKUP_F_INV)
 			priv->invert = true;
-		}
 	}
 
 	if (tb[NFTA_LOOKUP_DREG] != NULL) {
@@ -140,8 +138,17 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
 					       set->dlen);
 		if (err < 0)
 			return err;
-	} else if (set->flags & NFT_SET_MAP)
-		return -EINVAL;
+		priv->dreg_set = true;
+	} else if (set->flags & NFT_SET_MAP) {
+		/* Map given, but user asks for lookup only (i.e. to
+		 * ignore value assoicated with key).
+		 *
+		 * This makes no sense for anonymous maps since they are
+		 * scoped to the rule, but for named sets this can be useful.
+		 */
+		if (set->flags & NFT_SET_ANONYMOUS)
+			return -EINVAL;
+	}
 
 	priv->binding.flags = set->flags & NFT_SET_MAP;
 
@@ -188,7 +195,7 @@ static int nft_lookup_dump(struct sk_buff *skb,
 		goto nla_put_failure;
 	if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 		goto nla_put_failure;
-	if (priv->set->flags & NFT_SET_MAP)
+	if (priv->dreg_set)
 		if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 			goto nla_put_failure;
 	if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))