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l2tp: add support for IPv4-mapped IPv6 addresses

PATCH Superseded François Cachereul 2 participants 2 messages Sep 27, 2013 – Oct 1, 2013

Subsystems (2)
Networking Network drivers

v1 of 2 Superseded Latest is v2 →

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François Cachereul

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#0 lore raw

PATCH 1/1 l2tp: add support for IPv4-mapped IPv6 addresses

IPv4 mapped addresses cause kernel panic.
The patch juste check whether the IPv6 address is an IPv4 mapped address. If so, use IPv4 API instead of IPv6.

Signed-off-by François CACHEREUL <[email protected]>
---
 net/l2tp/l2tp_core.c |   28 ++++++++++++++++++++++++----
 net/l2tp/l2tp_core.h |    3 +++
 2 files changed, 27 insertions(+), 4 deletions(-)
net/l2tp/l2tp_core.c +24 -4
index feae495..731aa40 100644
@@ -496,6 +496,7 @@ out:
 static inline int l2tp_verify_udp_checksum(struct sock *sk,
 					   struct sk_buff *skb)
 {
+	struct l2tp_tunnel *tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
 	struct udphdr *uh = udp_hdr(skb);
 	u16 ulen = ntohs(uh->len);
 	__wsum psum;

@@ -504,7 +505,7 @@ static inline int l2tp_verify_udp_checksum(struct sock *sk,
 		return 0;
 
 #if IS_ENABLED(CONFIG_IPV6)
-	if (sk->sk_family == PF_INET6) {
+	if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) {
 		if (!uh->check) {
 			LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
 			return 1;

@@ -1128,7 +1129,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
 	/* Queue the packet to IP for output */
 	skb->local_df = 1;
 #if IS_ENABLED(CONFIG_IPV6)
-	if (skb->sk->sk_family == PF_INET6)
+	if (skb->sk->sk_family == PF_INET6 && !tunnel->v4mapped)
 		error = inet6_csk_xmit(skb, NULL);
 	else
 #endif

@@ -1255,7 +1256,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 
 		/* Calculate UDP checksum if configured to do so */
 #if IS_ENABLED(CONFIG_IPV6)
-		if (sk->sk_family == PF_INET6)
+		if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
 			l2tp_xmit_ipv6_csum(sk, skb, udp_len);
 		else
 #endif

@@ -1620,6 +1621,10 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	int err;
 	struct socket *sock = NULL;
 	struct sock *sk = NULL;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet_sock *inet = NULL;
+	struct ipv6_pinfo *np = NULL;
+#endif
 	struct l2tp_net *pn;
 	enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
 

@@ -1704,6 +1709,21 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	if (cfg != NULL)
 		tunnel->debug = cfg->debug;
 
+#if IS_ENABLED(CONFIG_IPV6)
+	np = inet6_sk(sk);
+	if (sk->sk_family == PF_INET6 &&
+	    ipv6_addr_v4mapped(&np->saddr) &&
+	    ipv6_addr_v4mapped(&np->daddr)) {
+		tunnel->v4mapped = true;
+		inet = inet_sk(sk);
+		inet->inet_saddr = np->saddr.s6_addr32[3];
+		inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3];
+		inet->inet_daddr = np->daddr.s6_addr32[3];
+	} else {
+		tunnel->v4mapped = false;
+	}
+#endif
+
 	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
 	tunnel->encap = encap;
 	if (encap == L2TP_ENCAPTYPE_UDP) {

@@ -1712,7 +1732,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 		udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
 		udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
 #if IS_ENABLED(CONFIG_IPV6)
-		if (sk->sk_family == PF_INET6)
+		if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
 			udpv6_encap_enable();
 		else
 #endif
net/l2tp/l2tp_core.h +3 -0
index 66a559b..6f251cb 100644
@@ -194,6 +194,9 @@ struct l2tp_tunnel {
 	struct sock		*sock;		/* Parent socket */
 	int			fd;		/* Parent fd, if tunnel socket
 						 * was created by userspace */
+#if IS_ENABLED(CONFIG_IPV6)
+	bool			v4mapped;
+#endif
 
 	struct work_struct	del_work;
Signature · 1 line
1.7.10.4
maintainer
#1 lore raw

From: François Cachereul <[email protected]>
Date: Fri, 27 Sep 2013 13:17:33 +0200

Quoted 8 lines
net/l2tp/l2tp_core.c +4 -0
@@ -1620,6 +1621,10 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	int err;
 	struct socket *sock = NULL;
 	struct sock *sk = NULL;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet_sock *inet = NULL;
+	struct ipv6_pinfo *np = NULL;
+#endif

...

Quoted 4 lines
net/l2tp/l2tp_core.c +4 -0
+#if IS_ENABLED(CONFIG_IPV6)
+	np = inet6_sk(sk);
+	if (sk->sk_family == PF_INET6 &&
+	    ipv6_addr_v4mapped(&np->saddr) &&

net/l2tp/l2tp_core.c int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 · line 1725

Quoted 10 lines
net/l2tp/l2tp_core.c +10 -0
+	    ipv6_addr_v4mapped(&np->daddr)) {
+		tunnel->v4mapped = true;
+		inet = inet_sk(sk);
+		inet->inet_saddr = np->saddr.s6_addr32[3];
+		inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3];
+		inet->inet_daddr = np->daddr.s6_addr32[3];
+	} else {
+		tunnel->v4mapped = false;
+	}
+#endif

You only need one ifdef here, get rid of the top level variable declarations and then just go:

#if IS_ENABLED(CONFIG_IPV6)
	if (sk->sk_family == PF_INET6) {
		struct ipv6_pinfo *np = inet6_sk(sk);

		if (ipv6_addr_v4mapped(&np->saddr) &&
		    ipv6_addr_v4mapped(&np->daddr)) {
			struct inet_sock *inet = inet_sk(sk);

			tunnel->v4mapped = true;
			inet->inet_saddr = np->saddr.s6_addr32[3];
			inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3];
			inet->inet_daddr = np->daddr.s6_addr32[3];
		} else {
			tunnel->v4mapped = false;
		}
	}

#endif