ipv4: namespacify ip fragment max dist sysctl knob

Signed-off-by: Nikolay Borisov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/inet_frag.h

···
 	int			timeout;
 	int			high_thresh;
 	int			low_thresh;
+	int			max_dist;
 };
 
 /**

net/ipv4/ip_fragment.c

···
  * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
  * as well. Or notify me, at least. --ANK
  */
-
-static int sysctl_ipfrag_max_dist __read_mostly = 64;
 static const char ip_frag_cache_name[] = "ip4-frags";
 
 struct ipfrag_skb_cb
···
 	qp->daddr = arg->iph->daddr;
 	qp->vif = arg->vif;
 	qp->user = arg->user;
-	qp->peer = sysctl_ipfrag_max_dist ?
+	qp->peer = q->net->max_dist ?
 		inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, arg->vif, 1) :
 		NULL;
 }
···
 static int ip_frag_too_far(struct ipq *qp)
 {
 	struct inet_peer *peer = qp->peer;
-	unsigned int max = sysctl_ipfrag_max_dist;
+	unsigned int max = qp->q.net->max_dist;
 	unsigned int start, end;
 
 	int rc;
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
+	{
+		.procname	= "ipfrag_max_dist",
+		.data		= &init_net.ipv4.frags.max_dist,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &zero
+	},
 	{ }
 };
 
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
-	},
-	{
-		.procname	= "ipfrag_max_dist",
-		.data		= &sysctl_ipfrag_max_dist,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero
 	},
 	{ }
 };
···
 		table[1].data = &net->ipv4.frags.low_thresh;
 		table[1].extra2 = &net->ipv4.frags.high_thresh;
 		table[2].data = &net->ipv4.frags.timeout;
+		table[3].data = &net->ipv4.frags.max_dist;
 
 		/* Don't export sysctls to unprivileged users */
 		if (net->user_ns != &init_user_ns)
···
 	 * by TTL.
 	 */
 	net->ipv4.frags.timeout = IP_FRAG_TIME;
+
+	net->ipv4.frags.max_dist = 64;
 
 	res = inet_frags_init_net(&net->ipv4.frags);
 	if (res)