netfilter: nf_log_syslog: Consolidate entry checks

Every syslog logging callback has to perform the same check to cover for
rogue containers, introduce a helper for clarity. Drop the FIXME as
there is a viable solution since commit 2851940ffee31 ("netfilter: allow
logging from non-init namespaces").

Suggested-by: Florian Westphal <[e-mail]>
Signed-off-by: Phil Sutter <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nf_log_syslog.c

···
 	unsigned char ip_dst[4];
 };
 
+/* Guard against containers flooding syslog. */
+static bool nf_log_allowed(const struct net *net)
+{
+	return net_eq(net, &init_net) || sysctl_nf_log_all_netns;
+}
+
 static void nf_log_dump_vlan(struct nf_log_buf *m, const struct sk_buff *skb)
 {
 	u16 vid;
···
 {
 	struct nf_log_buf *m;
 
-	/* FIXME: Disabled from containers until syslog ns is supported */
-	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
+	if (!nf_log_allowed(net))
 		return;
 
 	m = nf_log_buf_open();
···
 {
 	struct nf_log_buf *m;
 
-	/* FIXME: Disabled from containers until syslog ns is supported */
-	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
+	if (!nf_log_allowed(net))
 		return;
 
 	m = nf_log_buf_open();
···
 {
 	struct nf_log_buf *m;
 
-	/* FIXME: Disabled from containers until syslog ns is supported */
-	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
+	if (!nf_log_allowed(net))
 		return;
 
 	m = nf_log_buf_open();
···
 {
 	struct nf_log_buf *m;
 
-	/* FIXME: Disabled from containers until syslog ns is supported */
-	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
+	if (!nf_log_allowed(net))
 		return;
 
 	m = nf_log_buf_open();