ipv4: Namespaceify ip_default_ttl sysctl knob

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv4.h

@@ -80,6 +80,7 @@ struct netns_ipv4 {
 	int sysctl_tcp_ecn;
 	int sysctl_tcp_ecn_fallback;
 
+	int sysctl_ip_default_ttl;
 	int sysctl_ip_no_pmtu_disc;
 	int sysctl_ip_fwd_use_pmtu;
 	int sysctl_ip_nonlocal_bind;

include/net/route.h

@@ -329,14 +329,13 @@ static inline int inet_iif(const struct sk_buff *skb)
 	return skb->skb_iif;
 }
 
-extern int sysctl_ip_default_ttl;
-
 static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
 {
 	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
+	struct net *net = dev_net(dst->dev);
 
 	if (hoplimit == 0)
-		hoplimit = sysctl_ip_default_ttl;
+		hoplimit = net->ipv4.sysctl_ip_default_ttl;
 	return hoplimit;
 }
 

net/bridge/netfilter/nft_reject_bridge.c

@@ -48,6 +48,7 @@ static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb,
 	struct iphdr *niph;
 	const struct tcphdr *oth;
 	struct tcphdr _oth;
+	struct net *net = sock_net(oldskb->sk);
 
 	if (!nft_bridge_iphdr_validate(oldskb))
 		return;
@@ -63,9 +64,9 @@ static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb,
 
 	skb_reserve(nskb, LL_MAX_HEADER);
 	niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
-				   sysctl_ip_default_ttl);
+				   net->ipv4.sysctl_ip_default_ttl);
 	nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
-	niph->ttl	= sysctl_ip_default_ttl;
+	niph->ttl	= net->ipv4.sysctl_ip_default_ttl;
 	niph->tot_len	= htons(nskb->len);
 	ip_send_check(niph);
 
@@ -85,6 +86,7 @@ static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb,
 	void *payload;
 	__wsum csum;
 	u8 proto;
+	struct net *net = sock_net(oldskb->sk);
 
 	if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb))
 		return;
@@ -119,7 +121,7 @@ static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb,
 
 	skb_reserve(nskb, LL_MAX_HEADER);
 	niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
-				   sysctl_ip_default_ttl);
+				   net->ipv4.sysctl_ip_default_ttl);
 
 	skb_reset_transport_header(nskb);
 	icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr));

net/ipv4/ip_output.c

@@ -79,9 +79,6 @@
 #include <linux/netlink.h>
 #include <linux/tcp.h>
 
-int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
-EXPORT_SYMBOL(sysctl_ip_default_ttl);
-
 static int
 ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 	    unsigned int mtu,

net/ipv4/ip_sockglue.c

@@ -1341,10 +1341,13 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
 		val = inet->tos;
 		break;
 	case IP_TTL:
+	{
+		struct net *net = sock_net(sk);
 		val = (inet->uc_ttl == -1 ?
-		       sysctl_ip_default_ttl :
+		       net->ipv4.sysctl_ip_default_ttl :
 		       inet->uc_ttl);
 		break;
+	}
 	case IP_HDRINCL:
 		val = inet->hdrincl;
 		break;

net/ipv4/netfilter/ipt_SYNPROXY.c

@@ -21,6 +21,7 @@ static struct iphdr *
 synproxy_build_ip(struct sk_buff *skb, __be32 saddr, __be32 daddr)
 {
 	struct iphdr *iph;
+	struct net *net = sock_net(skb->sk);
 
 	skb_reset_network_header(skb);
 	iph = (struct iphdr *)skb_put(skb, sizeof(*iph));
@@ -29,7 +30,7 @@ synproxy_build_ip(struct sk_buff *skb, __be32 saddr, __be32 daddr)
 	iph->tos	= 0;
 	iph->id		= 0;
 	iph->frag_off	= htons(IP_DF);
-	iph->ttl	= sysctl_ip_default_ttl;
+	iph->ttl	= net->ipv4.sysctl_ip_default_ttl;
 	iph->protocol	= IPPROTO_TCP;
 	iph->check	= 0;
 	iph->saddr	= saddr;

net/ipv4/proc.c

@@ -390,7 +390,7 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
 
 	seq_printf(seq, "\nIp: %d %d",
 		   IPV4_DEVCONF_ALL(net, FORWARDING) ? 1 : 2,
-		   sysctl_ip_default_ttl);
+		   net->ipv4.sysctl_ip_default_ttl);
 
 	BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
 	for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)

net/ipv4/sysctl_net_ipv4.c

@@ -282,15 +282,6 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{
-		.procname	= "ip_default_ttl",
-		.data		= &sysctl_ip_default_ttl,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &ip_ttl_min,
-		.extra2		= &ip_ttl_max,
-	},
 	{
 		.procname	= "tcp_max_orphans",
 		.data		= &sysctl_tcp_max_orphans,
@@ -752,6 +743,15 @@ static struct ctl_table ipv4_net_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "ip_default_ttl",
+		.data		= &init_net.ipv4.sysctl_ip_default_ttl,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &ip_ttl_min,
+		.extra2		= &ip_ttl_max,
+	},
 	{
 		.procname	= "ip_local_port_range",
 		.maxlen		= sizeof(init_net.ipv4.ip_local_ports.range),
@@ -988,6 +988,8 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 	if (!net->ipv4.sysctl_local_reserved_ports)
 		goto err_ports;
 
+	net->ipv4.sysctl_ip_default_ttl = IPDEFTTL;
+
 	return 0;
 
 err_ports: