Netfilter-Devel Archive on
 help / color / Atom feed
From: Pablo Neira Ayuso <>
Subject: [PATCH 3/5] netfilter: nf_tables: allow lookups in dynamic sets
Date: Wed, 25 Sep 2019 22:30:01 +0200
Message-ID: <> (raw)
In-Reply-To: <>

From: Florian Westphal <>

This un-breaks lookups in sets that have the 'dynamic' flag set.
Given this active example configuration:

table filter {
  set set1 {
    type ipv4_addr
    size 64
    flags dynamic,timeout
    timeout 1m

  chain input {
     type filter hook input priority 0; policy accept;

... this works:
nft add rule ip filter input add @set1 { ip saddr }

-> whenever rule is triggered, the source ip address is inserted
into the set (if it did not exist).

This won't work:
nft add rule ip filter input ip saddr @set1 counter
Error: Could not process rule: Operation not supported

In other words, we can add entries to the set, but then can't make
matching decision based on that set.

That is just wrong -- all set backends support lookups (else they would
not be very useful).
The failure comes from an explicit rejection in nft_lookup.c.

Looking at the history, it seems like NFT_SET_EVAL used to mean
'set contains expressions' (aka. "is a meter"), for instance something like

 nft add rule ip filter input meter example { ip saddr limit rate 10/second }
 nft add rule ip filter input meter example { ip saddr counter }

The actual meaning of NFT_SET_EVAL however, is
'set can be updated from the packet path'.

'meters' and packet-path insertions into sets, such as
'add @set { ip saddr }' use exactly the same kernel code (nft_dynset.c)
and thus require a set backend that provides the ->update() function.

The only set that provides this also is the only one that has the
NFT_SET_EVAL feature flag.

Removing the wrong check makes the above example work.
While at it, also fix the flag check during set instantiation to
allow supported combinations only.

Fixes: 8aeff920dcc9b3f ("netfilter: nf_tables: add stateful object reference to set elements")
Signed-off-by: Florian Westphal <>
Signed-off-by: Pablo Neira Ayuso <>
 net/netfilter/nf_tables_api.c | 7 +++++--
 net/netfilter/nft_lookup.c    | 3 ---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4a5d6ef2b706..6dc46f9b5f7b 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3562,8 +3562,11 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
 			return -EINVAL;
 		/* Only one of these operations is supported */
-		if ((flags & (NFT_SET_MAP | NFT_SET_EVAL | NFT_SET_OBJECT)) ==
+		if ((flags & (NFT_SET_MAP | NFT_SET_OBJECT)) ==
+			return -EOPNOTSUPP;
+		if ((flags & (NFT_SET_EVAL | NFT_SET_OBJECT)) ==
 			return -EOPNOTSUPP;
diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index c0560bf3c31b..660bad688e2b 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -73,9 +73,6 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
 	if (IS_ERR(set))
 		return PTR_ERR(set);
-	if (set->flags & NFT_SET_EVAL)
-		return -EOPNOTSUPP;
 	priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
 	err = nft_validate_register_load(priv->sreg, set->klen);
 	if (err < 0)

  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 20:29 [PATCH 0/5] Netfilter fixes for net Pablo Neira Ayuso
2019-09-25 20:29 ` [PATCH 1/5] netfilter: nf_tables: add NFT_CHAIN_POLICY_UNSET and use it Pablo Neira Ayuso
2019-09-25 20:30 ` [PATCH 2/5] netfilter: nf_tables_offload: fix always true policy is unset check Pablo Neira Ayuso
2019-09-25 20:30 ` Pablo Neira Ayuso [this message]
2019-09-25 20:30 ` [PATCH 4/5] netfilter: ebtables: use __u8 instead of uint8_t in uapi header Pablo Neira Ayuso
2019-09-25 20:30 ` [PATCH 5/5] netfilter: nf_tables: bogus EBUSY when deleting flowtable after flush Pablo Neira Ayuso
2019-09-27 18:16 ` [PATCH 0/5] Netfilter fixes for net David Miller

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Netfilter-Devel Archive on

Archives are clonable:
	git clone --mirror netfilter-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 netfilter-devel netfilter-devel/ \
	public-inbox-index netfilter-devel

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone