Commit 90d1daa4 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: conntrack: add nf_conntrack_events autodetect mode 



This adds the new nf_conntrack_events=2 mode and makes it the
default.

This leverages the earlier flag in struct net to allow to avoid
the event extension as long as no event listener is active in
the namespace.

This avoids, for most cases, allocation of ct->ext area.
A followup patch will take further advantage of this by avoiding
calls down into the event framework if the extension isn't present.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent b0a7ab4a

Documentation/networking/nf_conntrack-sysctl.rst

+4 −1
Original line number Diff line number Diff line
@@ -34,10 +34,13 @@ nf_conntrack_count - INTEGER (read-only) 


nf_conntrack_events - BOOLEAN

	- 0 - disabled

	- not 0 - enabled (default)

	- 1 - enabled

	- 2 - auto (default)



	If this option is enabled, the connection tracking code will

	provide userspace with connection tracking events via ctnetlink.

	The default allocates the extension if a userspace program is

	listening to ctnetlink events.



nf_conntrack_expect_max - INTEGER

	Maximum size of expectation table.  Default value is

net/netfilter/nf_conntrack_core.c

+2 −1
Original line number Diff line number Diff line
@@ -1736,7 +1736,8 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, 
#ifdef CONFIG_NF_CONNTRACK_EVENTS

	ecache = tmpl ? nf_ct_ecache_find(tmpl) : NULL;



	if (!nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,

	if ((ecache || net->ct.sysctl_events) &&

	    !nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,

				  ecache ? ecache->expmask : 0,

				  GFP_ATOMIC)) {

		nf_conntrack_free(ct);

net/netfilter/nf_conntrack_ecache.c

+21 −6
Original line number Diff line number Diff line
@@ -302,12 +302,27 @@ bool nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp 
	struct net *net = nf_ct_net(ct);

	struct nf_conntrack_ecache *e;



	if (!ctmask && !expmask && net->ct.sysctl_events) {

	switch (net->ct.sysctl_events) {

	case 0:

		 /* assignment via template / ruleset? ignore sysctl. */

		if (ctmask || expmask)

			break;

		return true;

	case 2: /* autodetect: no event listener, don't allocate extension. */

		if (!READ_ONCE(net->ct.ctnetlink_has_listener))

			return true;

		fallthrough;

	case 1:

		/* always allocate an extension. */

		if (!ctmask && !expmask) {

			ctmask = ~0;

			expmask = ~0;

		}

	if (!ctmask && !expmask)

		return false;

		break;

	default:

		WARN_ON_ONCE(1);

		return true;

	}



	e = nf_ct_ext_add(ct, NF_CT_EXT_ECACHE, gfp);

	if (e) {
@@ -319,7 +334,7 @@ bool nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp 
}

EXPORT_SYMBOL_GPL(nf_ct_ecache_ext_add);



#define NF_CT_EVENTS_DEFAULT 1

#define NF_CT_EVENTS_DEFAULT 2

static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;



void nf_conntrack_ecache_pernet_init(struct net *net)

net/netfilter/nf_conntrack_standalone.c

+1 −1
Original line number Diff line number Diff line
@@ -693,7 +693,7 @@ static struct ctl_table nf_ct_sysctl_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dou8vec_minmax,

		.extra1 	= SYSCTL_ZERO,

		.extra2 	= SYSCTL_ONE,

		.extra2		= SYSCTL_TWO,

	},

#endif

#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP