To avoid allocation of the conntrack extension area when possible,
the default behaviour was changed to only allocate the event extension
if a userspace program is subscribed to a notification group.
Problem is that while 'conntrack -E' does enable the event allocation
behind the scenes, 'conntrack -E expect' does not: no expectation events
are delivered unless user sets
"net.netfilter.nf_conntrack_events" back to 1 (always on).
Fix the autodetection to also consider EXP type group.
We need to track the 6 event groups (3+3, new/update/destroy for events and
for expectations each) independently, else we'd disable events again
if an expectation group becomes empty while there is still an active
event group.
Fixes: 2794cdb0b97b ("netfilter: nfnetlink: allow to detect if ctnetlink listeners exist")
Reported-by: Yi Chen <yiche@xxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
include/net/netns/conntrack.h | 2 +-
net/netfilter/nfnetlink.c | 83 ++++++++++++++++++++++++++++++-----
2 files changed, 72 insertions(+), 13 deletions(-)
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index 0677cd3de034..c396a3862e80 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -95,7 +95,7 @@ struct nf_ip_net {
struct netns_ct {
#ifdef CONFIG_NF_CONNTRACK_EVENTS
- bool ctnetlink_has_listener;
+ u8 ctnetlink_has_listener;
bool ecache_dwork_pending;
#endif
u8 sysctl_log_invalid; /* Log invalid packets */
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index c24b1240908f..6c268f1c201a 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -44,6 +44,10 @@ MODULE_DESCRIPTION("Netfilter messages via netlink socket");
static unsigned int nfnetlink_pernet_id __read_mostly;
+#ifdef CONFIG_NF_CONNTRACK_EVENTS
+static DEFINE_SPINLOCK(nfnl_grp_active_lock);
+#endif
+
struct nfnl_net {
struct sock *nfnl;
};
@@ -654,6 +658,44 @@ static void nfnetlink_rcv(struct sk_buff *skb)
netlink_rcv_skb(skb, nfnetlink_rcv_msg);
}
+static void nfnetlink_bind_event(struct net *net, unsigned int group)
+{
+#ifdef CONFIG_NF_CONNTRACK_EVENTS
+ int type, group_bit;
+ u8 v;
+
+ /* ctnetlink_has_listener is u8, all NFNLGRP_CONNTRACK_* groups
+ * coming from userspace are < 8.
+ */
+ if (group >= 8)
+ return;
+
+ type = nfnl_group2type[group];
+
+ switch (type) {
+ case NFNL_SUBSYS_CTNETLINK:
+ break;
+ case NFNL_SUBSYS_CTNETLINK_EXP:
+ break;
+ default:
+ return;
+ }
+
+ group_bit = (1 << group);
+
+ spin_lock(&nfnl_grp_active_lock);
+ v = READ_ONCE(net->ct.ctnetlink_has_listener);
+ if ((v & group_bit) == 0) {
+ v |= group_bit;
+
+ /* read concurrently without nfnl_grp_active_lock held. */
+ WRITE_ONCE(net->ct.ctnetlink_has_listener, v);
+ }
+
+ spin_unlock(&nfnl_grp_active_lock);
+#endif
+}
+
static int nfnetlink_bind(struct net *net, int group)
{
const struct nfnetlink_subsystem *ss;
@@ -670,28 +712,45 @@ static int nfnetlink_bind(struct net *net, int group)
if (!ss)
request_module_nowait("nfnetlink-subsys-%d", type);
-#ifdef CONFIG_NF_CONNTRACK_EVENTS
- if (type == NFNL_SUBSYS_CTNETLINK) {
- nfnl_lock(NFNL_SUBSYS_CTNETLINK);
- WRITE_ONCE(net->ct.ctnetlink_has_listener, true);
- nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
- }
-#endif
+ nfnetlink_bind_event(net, group);
return 0;
}
static void nfnetlink_unbind(struct net *net, int group)
{
#ifdef CONFIG_NF_CONNTRACK_EVENTS
+ int type, group_bit;
+
if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
return;
- if (nfnl_group2type[group] == NFNL_SUBSYS_CTNETLINK) {
- nfnl_lock(NFNL_SUBSYS_CTNETLINK);
- if (!nfnetlink_has_listeners(net, group))
- WRITE_ONCE(net->ct.ctnetlink_has_listener, false);
- nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
+ type = nfnl_group2type[group];
+
+ switch (type) {
+ case NFNL_SUBSYS_CTNETLINK:
+ break;
+ case NFNL_SUBSYS_CTNETLINK_EXP:
+ break;
+ default:
+ return;
+ }
+
+ /* ctnetlink_has_listener is u8 */
+ if (group >= 8)
+ return;
+
+ group_bit = (1 << group);
+
+ spin_lock(&nfnl_grp_active_lock);
+ if (!nfnetlink_has_listeners(net, group)) {
+ u8 v = READ_ONCE(net->ct.ctnetlink_has_listener);
+
+ v &= ~group_bit;
+
+ /* read concurrently without nfnl_grp_active_lock held. */
+ WRITE_ONCE(net->ct.ctnetlink_has_listener, v);
}
+ spin_unlock(&nfnl_grp_active_lock);
#endif
}
--
2.35.1
