xfrm: add IPv6 support for espintcp

This extends espintcp to support IPv6, building on the existing code
and the new UDPv6 encapsulation support. Most of the code is either
reused directly (stream parser, ULP) or very similar to the IPv4
variant (net/ipv6/esp6.c changes).

The separation of config options for IPv4 and IPv6 espintcp requires a
bit of Kconfig gymnastics to enable the core code.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

3 files changed, 49 insertions, 12 deletions

diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
index 6921a18201a0..b7fd9c838416 100644
--- a/net/xfrm/Kconfig
+++ b/net/xfrm/Kconfig
@@ -99,4 +99,7 @@ config NET_KEY_MIGRATE
 
 	  If unsure, say N.
 
+config XFRM_ESPINTCP
+	bool
+
 endif # INET
diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile
index 212a4fcb4a88..2d4bb4b9f75e 100644
--- a/net/xfrm/Makefile
+++ b/net/xfrm/Makefile
@@ -11,4 +11,4 @@ obj-$(CONFIG_XFRM_ALGO) += xfrm_algo.o
 obj-$(CONFIG_XFRM_USER) += xfrm_user.o
 obj-$(CONFIG_XFRM_IPCOMP) += xfrm_ipcomp.o
 obj-$(CONFIG_XFRM_INTERFACE) += xfrm_interface.o
-obj-$(CONFIG_INET_ESPINTCP) += espintcp.o
+obj-$(CONFIG_XFRM_ESPINTCP) += espintcp.o
diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
index 037ea156d2f9..2132a3b6df0f 100644
--- a/net/xfrm/espintcp.c
+++ b/net/xfrm/espintcp.c
@@ -6,6 +6,9 @@
 #include <net/espintcp.h>
 #include <linux/skmsg.h>
 #include <net/inet_common.h>
+#if IS_ENABLED(CONFIG_IPV6)
+#include <net/ipv6_stubs.h>
+#endif
 
 static void handle_nonesp(struct espintcp_ctx *ctx, struct sk_buff *skb,
 			  struct sock *sk)
@@ -31,7 +34,12 @@ static void handle_esp(struct sk_buff *skb, struct sock *sk)
 	rcu_read_lock();
 	skb->dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif);
 	local_bh_disable();
-	xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP);
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		ipv6_stub->xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP);
+	else
+#endif
+		xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP);
 	local_bh_enable();
 	rcu_read_unlock();
 }
@@ -347,6 +355,9 @@ unlock:
 
 static struct proto espintcp_prot __ro_after_init;
 static struct proto_ops espintcp_ops __ro_after_init;
+static struct proto espintcp6_prot;
+static struct proto_ops espintcp6_ops;
+static DEFINE_MUTEX(tcpv6_prot_mutex);
 
 static void espintcp_data_ready(struct sock *sk)
 {
@@ -384,10 +395,14 @@ static void espintcp_destruct(struct sock *sk)
 
 bool tcp_is_ulp_esp(struct sock *sk)
 {
-	return sk->sk_prot == &espintcp_prot;
+	return sk->sk_prot == &espintcp_prot || sk->sk_prot == &espintcp6_prot;
 }
 EXPORT_SYMBOL_GPL(tcp_is_ulp_esp);
 
+static void build_protos(struct proto *espintcp_prot,
+			 struct proto_ops *espintcp_ops,
+			 const struct proto *orig_prot,
+			 const struct proto_ops *orig_ops);
 static int espintcp_init_sk(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -415,8 +430,19 @@ static int espintcp_init_sk(struct sock *sk)
 	strp_check_rcv(&ctx->strp);
 	skb_queue_head_init(&ctx->ike_queue);
 	skb_queue_head_init(&ctx->out_queue);
-	sk->sk_prot = &espintcp_prot;
-	sk->sk_socket->ops = &espintcp_ops;
+
+	if (sk->sk_family == AF_INET) {
+		sk->sk_prot = &espintcp_prot;
+		sk->sk_socket->ops = &espintcp_ops;
+	} else {
+		mutex_lock(&tcpv6_prot_mutex);
+		if (!espintcp6_prot.recvmsg)
+			build_protos(&espintcp6_prot, &espintcp6_ops, sk->sk_prot, sk->sk_socket->ops);
+		mutex_unlock(&tcpv6_prot_mutex);
+
+		sk->sk_prot = &espintcp6_prot;
+		sk->sk_socket->ops = &espintcp6_ops;
+	}
 	ctx->saved_data_ready = sk->sk_data_ready;
 	ctx->saved_write_space = sk->sk_write_space;
 	sk->sk_data_ready = espintcp_data_ready;
@@ -489,6 +515,20 @@ static __poll_t espintcp_poll(struct file *file, struct socket *sock,
 	return mask;
 }
 
+static void build_protos(struct proto *espintcp_prot,
+			 struct proto_ops *espintcp_ops,
+			 const struct proto *orig_prot,
+			 const struct proto_ops *orig_ops)
+{
+	memcpy(espintcp_prot, orig_prot, sizeof(struct proto));
+	memcpy(espintcp_ops, orig_ops, sizeof(struct proto_ops));
+	espintcp_prot->sendmsg = espintcp_sendmsg;
+	espintcp_prot->recvmsg = espintcp_recvmsg;
+	espintcp_prot->close = espintcp_close;
+	espintcp_prot->release_cb = espintcp_release;
+	espintcp_ops->poll = espintcp_poll;
+}
+
 static struct tcp_ulp_ops espintcp_ulp __read_mostly = {
 	.name = "espintcp",
 	.owner = THIS_MODULE,
@@ -497,13 +537,7 @@ static struct tcp_ulp_ops espintcp_ulp __read_mostly = {
 
 void __init espintcp_init(void)
 {
-	memcpy(&espintcp_prot, &tcp_prot, sizeof(tcp_prot));
-	memcpy(&espintcp_ops, &inet_stream_ops, sizeof(inet_stream_ops));
-	espintcp_prot.sendmsg = espintcp_sendmsg;
-	espintcp_prot.recvmsg = espintcp_recvmsg;
-	espintcp_prot.close = espintcp_close;
-	espintcp_prot.release_cb = espintcp_release;
-	espintcp_ops.poll = espintcp_poll;
+	build_protos(&espintcp_prot, &espintcp_ops, &tcp_prot, &inet_stream_ops);
 
 	tcp_register_ulp(&espintcp_ulp);
 }