igmp: Fix regression caused by igmp sysctl namespace code.

Commit dcd87999 ("igmp: net: Move igmp namespace init to correct file")
moved the igmp sysctls initialization from tcp_sk_init to igmp_net_init. This
function is only called as part of per-namespace initialization, only if
CONFIG_IP_MULTICAST is defined, otherwise igmp_mc_init() call in ip_init is
compiled out, casuing the igmp pernet ops to not be registerd and those sysctl
being left initialized with 0. However, there are certain functions, such as
ip_mc_join_group which are always compiled and make use of some of those
sysctls. Let's do a partial revert of the aforementioned commit and move the
sysctl initialization into inet_init_net, that way they will always have
sane values.

Fixes: dcd87999 ("igmp: net: Move igmp namespace init to correct file")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=196595Reported-by: NGerardo Exequiel Pozzi <vmlinuz386@gmail.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -1731,6 +1731,13 @@ static __net_init int inet_init_net(struct net *net)
 	net->ipv4.sysctl_ip_prot_sock = PROT_SOCK;
 #endif
 
+	/* Some igmp sysctl, whose values are always used */
+	net->ipv4.sysctl_igmp_max_memberships = 20;
+	net->ipv4.sysctl_igmp_max_msf = 10;
+	/* IGMP reports for link-local multicast groups are enabled by default */
+	net->ipv4.sysctl_igmp_llm_reports = 1;
+	net->ipv4.sysctl_igmp_qrv = 2;
+
 	return 0;
 }
 

net/ipv4/igmp.c

@@ -2974,12 +2974,6 @@ static int __net_init igmp_net_init(struct net *net)
 		goto out_sock;
 	}
 
-	/* Sysctl initialization */
-	net->ipv4.sysctl_igmp_max_memberships = 20;
-	net->ipv4.sysctl_igmp_max_msf = 10;
-	/* IGMP reports for link-local multicast groups are enabled by default */
-	net->ipv4.sysctl_igmp_llm_reports = 1;
-	net->ipv4.sysctl_igmp_qrv = 2;
 	return 0;
 
 out_sock: