[PATCH net-next v2] tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

[PATCH net-next v2] tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

[Christoph Paasch]

A socket may be v6/v4-mapped. In that case sk->sk_family is AF_INET6,
but the IP being used is actually an IPv4-address.
Current's tcp-metrics will thus represent it as an IPv6-address:

root@server:~# ip tcp_metrics
::ffff:10.1.1.2 age 22.920sec rtt 18750us rttvar 15000us cwnd 10
10.1.1.2 age 47.970sec rtt 16250us rttvar 10000us cwnd 10

This patch modifies the tcp-metrics so that they are able to handle the
v6/v4-mapped sockets correctly.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
---
v2: Respin to net-next.

 net/ipv4/tcp_metrics.c | 64 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index fa950941de65..9923cebf5709 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -274,24 +274,32 @@ static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock
 	unsigned int hash;
 	struct net *net;
 
-	saddr.family = tw->tw_family;
-	daddr.family = tw->tw_family;
-	switch (daddr.family) {
-	case AF_INET:
+	if (tw->tw_family == AF_INET) {
+		saddr.family = AF_INET;
 		saddr.addr.a4 = tw->tw_rcv_saddr;
+		daddr.family = AF_INET;
 		daddr.addr.a4 = tw->tw_daddr;
 		hash = (__force unsigned int) daddr.addr.a4;
-		break;
+	}
 #if IS_ENABLED(CONFIG_IPV6)
-	case AF_INET6:
-		*(struct in6_addr *)saddr.addr.a6 = tw->tw_v6_rcv_saddr;
-		*(struct in6_addr *)daddr.addr.a6 = tw->tw_v6_daddr;
-		hash = ipv6_addr_hash(&tw->tw_v6_daddr);
-		break;
+	else if (tw->tw_family == AF_INET6) {
+		if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
+			saddr.family = AF_INET;
+			saddr.addr.a4 = tw->tw_rcv_saddr;
+			daddr.family = AF_INET;
+			daddr.addr.a4 = tw->tw_daddr;
+			hash = (__force unsigned int) daddr.addr.a4;
+		} else {
+			saddr.family = AF_INET6;
+			*(struct in6_addr *)saddr.addr.a6 = tw->tw_v6_rcv_saddr;
+			daddr.family = AF_INET6;
+			*(struct in6_addr *)daddr.addr.a6 = tw->tw_v6_daddr;
+			hash = ipv6_addr_hash(&tw->tw_v6_daddr);
+		}
+	}
 #endif
-	default:
+	else
 		return NULL;
-	}
 
 	net = twsk_net(tw);
 	hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
@@ -314,24 +322,32 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 	unsigned int hash;
 	struct net *net;
 
-	saddr.family = sk->sk_family;
-	daddr.family = sk->sk_family;
-	switch (daddr.family) {
-	case AF_INET:
+	if (sk->sk_family == AF_INET) {
+		saddr.family = AF_INET;
 		saddr.addr.a4 = inet_sk(sk)->inet_saddr;
+		daddr.family = AF_INET;
 		daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 		hash = (__force unsigned int) daddr.addr.a4;
-		break;
+	}
 #if IS_ENABLED(CONFIG_IPV6)
-	case AF_INET6:
-		*(struct in6_addr *)saddr.addr.a6 = sk->sk_v6_rcv_saddr;
-		*(struct in6_addr *)daddr.addr.a6 = sk->sk_v6_daddr;
-		hash = ipv6_addr_hash(&sk->sk_v6_daddr);
-		break;
+	else if (sk->sk_family = AF_INET6) {
+		if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
+			saddr.family = AF_INET;
+			saddr.addr.a4 = inet_sk(sk)->inet_saddr;
+			daddr.family = AF_INET;
+			daddr.addr.a4 = inet_sk(sk)->inet_daddr;
+			hash = (__force unsigned int) daddr.addr.a4;
+		} else {
+			saddr.family = AF_INET6;
+			*(struct in6_addr *)saddr.addr.a6 = sk->sk_v6_rcv_saddr;
+			daddr.family = AF_INET6;
+			*(struct in6_addr *)daddr.addr.a6 = sk->sk_v6_daddr;
+			hash = ipv6_addr_hash(&sk->sk_v6_daddr);
+		}
+	}
 #endif
-	default:
+	else
 		return NULL;
-	}
 
 	net = dev_net(dst->dev);
 	hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
-- 
1.8.3.2

Re: [PATCH net-next v2] tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

[Eric Dumazet]

On Wed, 2014-01-22 at 13:58 +0100, Christoph Paasch wrote:
> A socket may be v6/v4-mapped. In that case sk->sk_family is AF_INET6,
> but the IP being used is actually an IPv4-address.
> Current's tcp-metrics will thus represent it as an IPv6-address:
> 
> root@server:~# ip tcp_metrics
> ::ffff:10.1.1.2 age 22.920sec rtt 18750us rttvar 15000us cwnd 10
> 10.1.1.2 age 47.970sec rtt 16250us rttvar 10000us cwnd 10
> 
> This patch modifies the tcp-metrics so that they are able to handle the
> v6/v4-mapped sockets correctly.
> 
> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
> ---

Acked-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH net-next v2] tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

[David Miller]

From: Christoph Paasch <christoph.paasch@uclouvain.be>
Date: Wed, 22 Jan 2014 13:58:44 +0100

> A socket may be v6/v4-mapped. In that case sk->sk_family is AF_INET6,
> but the IP being used is actually an IPv4-address.
> Current's tcp-metrics will thus represent it as an IPv6-address:
> 
> root@server:~# ip tcp_metrics
> ::ffff:10.1.1.2 age 22.920sec rtt 18750us rttvar 15000us cwnd 10
> 10.1.1.2 age 47.970sec rtt 16250us rttvar 10000us cwnd 10
> 
> This patch modifies the tcp-metrics so that they are able to handle the
> v6/v4-mapped sockets correctly.
> 
> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>

Applied, but I guess you didn't look at the build warnings, nor thoroughly
test this:

> +	else if (sk->sk_family = AF_INET6) {

That's an assignment, not a straight test, and the compiler warns
about it.

I fixed it when I applied this, but please don't be so sloppy in the
future.

Re: [PATCH net-next v2] tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

[Christoph Paasch]

On 23/01/14 - 12:49:26, David Miller wrote:
> From: Christoph Paasch <christoph.paasch@uclouvain.be>
> Date: Wed, 22 Jan 2014 13:58:44 +0100
> 
> > A socket may be v6/v4-mapped. In that case sk->sk_family is AF_INET6,
> > but the IP being used is actually an IPv4-address.
> > Current's tcp-metrics will thus represent it as an IPv6-address:
> > 
> > root@server:~# ip tcp_metrics
> > ::ffff:10.1.1.2 age 22.920sec rtt 18750us rttvar 15000us cwnd 10
> > 10.1.1.2 age 47.970sec rtt 16250us rttvar 10000us cwnd 10
> > 
> > This patch modifies the tcp-metrics so that they are able to handle the
> > v6/v4-mapped sockets correctly.
> > 
> > Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
> 
> Applied, but I guess you didn't look at the build warnings, nor thoroughly
> test this:
> 
> > +	else if (sk->sk_family = AF_INET6) {
> 
> That's an assignment, not a straight test, and the compiler warns
> about it.
> 
> I fixed it when I applied this, but please don't be so sloppy in the
> future.

Ouch, I'm really sorry. Thanks for fixing it.

I did actually test it and it worked, because if sk_family is not AF_INET
then it can only be AF_INET6 and so the assignment won't change sk_family
and the if condition will be true.

Anyways, I will pay more attention in the future.

Thanks!