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netfilter: nft_ct: allow to set ctnetlink event types of a connection

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By default the kernel emits all ctnetlink events for a connection.
This allows to select the types of events to generate.

This can be used to e.g. only send DESTROY events but no NEW/UPDATE ones
and will work even if sysctl net.netfilter.nf_conntrack_events is set to 0.

This was already possible via iptables' CT target, but the nft version has
the advantage that it can also be used with already-established conntracks.

The added nf_ct_is_template() check isn't a bug fix as we only support
mark and labels (and unlike ecache the conntrack core doesn't copy those).

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-04-15 19:26:10 +02:00 committed by Pablo Neira Ayuso
parent ab8bc7ed86
commit 694a0055f0
2 changed files with 26 additions and 1 deletions
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2
include/uapi/linux/netfilter/nf_tables.h
View File

@ -901,6 +901,7 @@ enum nft_rt_attributes {
* @NFT_CT_BYTES: conntrack bytes
* @NFT_CT_AVGPKT: conntrack average bytes per packet
* @NFT_CT_ZONE: conntrack zone
* @NFT_CT_EVENTMASK: ctnetlink events to be generated for this conntrack
*/
enum nft_ct_keys {
NFT_CT_STATE,
@ -921,6 +922,7 @@ enum nft_ct_keys {
NFT_CT_BYTES,
NFT_CT_AVGPKT,
NFT_CT_ZONE,
NFT_CT_EVENTMASK,
};
/**

25
net/netfilter/nft_ct.c
View File

@ -264,7 +264,7 @@ static void nft_ct_set_eval(const struct nft_expr *expr,
struct nf_conn *ct;
ct = nf_ct_get(skb, &ctinfo);
if (ct == NULL)
if (ct == NULL || nf_ct_is_template(ct))
return;
switch (priv->key) {
@ -283,6 +283,22 @@ static void nft_ct_set_eval(const struct nft_expr *expr,
&regs->data[priv->sreg],
NF_CT_LABELS_MAX_SIZE / sizeof(u32));
break;
#endif
#ifdef CONFIG_NF_CONNTRACK_EVENTS
case NFT_CT_EVENTMASK: {
struct nf_conntrack_ecache *e = nf_ct_ecache_find(ct);
u32 ctmask = regs->data[priv->sreg];
if (e) {
if (e->ctmask != ctmask)
e->ctmask = ctmask;
break;
}
if (ctmask && !nf_ct_is_confirmed(ct))
nf_ct_ecache_ext_add(ct, ctmask, 0, GFP_ATOMIC);
break;
}
#endif
default:
break;
@ -538,6 +554,13 @@ static int nft_ct_set_init(const struct nft_ctx *ctx,
nft_ct_pcpu_template_refcnt++;
len = sizeof(u16);
break;
#endif
#ifdef CONFIG_NF_CONNTRACK_EVENTS
case NFT_CT_EVENTMASK:
if (tb[NFTA_CT_DIRECTION])
return -EINVAL;
len = sizeof(u32);
break;
#endif
default:
return -EOPNOTSUPP;