icmp: icmp_msgs_per_sec and icmp_msgs_burst sysctls become per netns

Previous patch made ICMP rate limits per netns, it makes sense
to allow each netns to change the associated sysctl.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20240829144641.3880376-4-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/ip.h

@@ -797,9 +797,6 @@ static inline void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
 bool icmp_global_allow(struct net *net);
 void icmp_global_consume(struct net *net);
 
-extern int sysctl_icmp_msgs_per_sec;
-extern int sysctl_icmp_msgs_burst;
-
 #ifdef CONFIG_PROC_FS
 int ip_misc_proc_init(void);
 #endif

include/net/netns/ipv4.h

@@ -122,6 +122,8 @@ struct netns_ipv4 {
 	u8 sysctl_icmp_errors_use_inbound_ifaddr;
 	int sysctl_icmp_ratelimit;
 	int sysctl_icmp_ratemask;
+	int sysctl_icmp_msgs_per_sec;
+	int sysctl_icmp_msgs_burst;
 	atomic_t icmp_global_credit;
 	u32 icmp_global_stamp;
 	u32 ip_rt_min_pmtu;

net/ipv4/icmp.c

@@ -220,9 +220,6 @@ static inline void icmp_xmit_unlock(struct sock *sk)
 	spin_unlock(&sk->sk_lock.slock);
 }
 
-int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
-int sysctl_icmp_msgs_burst __read_mostly = 50;
-
 /**
  * icmp_global_allow - Are we allowed to send one more ICMP message ?
  * @net: network namespace
@@ -249,14 +246,14 @@ bool icmp_global_allow(struct net *net)
 	if (delta < HZ / 50)
 		return false;
 
-	incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
+	incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ;
 	if (!incr)
 		return false;
 
 	if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) {
 		old = atomic_read(&net->ipv4.icmp_global_credit);
 		do {
-			new = min(old + incr, READ_ONCE(sysctl_icmp_msgs_burst));
+			new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst));
 		} while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new));
 	}
 	return true;
@@ -1492,6 +1489,8 @@ static int __net_init icmp_sk_init(struct net *net)
 	net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
 	net->ipv4.sysctl_icmp_ratemask = 0x1818;
 	net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
+	net->ipv4.sysctl_icmp_msgs_per_sec = 1000;
+	net->ipv4.sysctl_icmp_msgs_burst = 50;
 
 	return 0;
 }

net/ipv4/sysctl_net_ipv4.c

@@ -600,22 +600,6 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0444,
 		.proc_handler   = proc_tcp_available_ulp,
 	},
-	{
-		.procname	= "icmp_msgs_per_sec",
-		.data		= &sysctl_icmp_msgs_per_sec,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
-	{
-		.procname	= "icmp_msgs_burst",
-		.data		= &sysctl_icmp_msgs_burst,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
 	{
 		.procname	= "udp_mem",
 		.data		= &sysctl_udp_mem,
@@ -701,6 +685,22 @@ static struct ctl_table ipv4_net_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "icmp_msgs_per_sec",
+		.data		= &init_net.ipv4.sysctl_icmp_msgs_per_sec,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+	},
+	{
+		.procname	= "icmp_msgs_burst",
+		.data		= &init_net.ipv4.sysctl_icmp_msgs_burst,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+	},
 	{
 		.procname	= "ping_group_range",
 		.data		= &init_net.ipv4.ping_group_range.range,