1 files changed, 118 insertions, 0 deletions
diff --git a/net/ipv4/xfrm4_tunnel.c b/net/ipv4/xfrm4_tunnel.c
new file mode 100644
index 000000000..8489fa106
--- /dev/null
+++ b/net/ipv4/xfrm4_tunnel.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* xfrm4_tunnel.c: Generic IP tunnel transformer.
+ *
+ * Copyright (C) 2003 David S. Miller (davem@redhat.com)
+ */
+
+#define pr_fmt(fmt) "IPsec: " fmt
+
+#include <linux/skbuff.h>
+#include <linux/module.h>
+#include <net/xfrm.h>
+#include <net/protocol.h>
+
+static int ipip_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	skb_push(skb, -skb_network_offset(skb));
+	return 0;
+}
+
+static int ipip_xfrm_rcv(struct xfrm_state *x, struct sk_buff *skb)
+{
+	return ip_hdr(skb)->protocol;
+}
+
+static int ipip_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
+{
+	if (x->props.mode != XFRM_MODE_TUNNEL) {
+		NL_SET_ERR_MSG(extack, "IPv4 tunnel can only be used with tunnel mode");
+		return -EINVAL;
+	}
+
+	if (x->encap) {
+		NL_SET_ERR_MSG(extack, "IPv4 tunnel is not compatible with encapsulation");
+		return -EINVAL;
+	}
+
+	x->props.header_len = sizeof(struct iphdr);
+
+	return 0;
+}
+
+static void ipip_destroy(struct xfrm_state *x)
+{
+}
+
+static const struct xfrm_type ipip_type = {
+	.owner		= THIS_MODULE,
+	.proto	     	= IPPROTO_IPIP,
+	.init_state	= ipip_init_state,
+	.destructor	= ipip_destroy,
+	.input		= ipip_xfrm_rcv,
+	.output		= ipip_output
+};
+
+static int xfrm_tunnel_rcv(struct sk_buff *skb)
+{
+	return xfrm4_rcv_spi(skb, IPPROTO_IPIP, ip_hdr(skb)->saddr);
+}
+
+static int xfrm_tunnel_err(struct sk_buff *skb, u32 info)
+{
+	return -ENOENT;
+}
+
+static struct xfrm_tunnel xfrm_tunnel_handler __read_mostly = {
+	.handler	=	xfrm_tunnel_rcv,
+	.err_handler	=	xfrm_tunnel_err,
+	.priority	=	4,
+};
+
+#if IS_ENABLED(CONFIG_IPV6)
+static struct xfrm_tunnel xfrm64_tunnel_handler __read_mostly = {
+	.handler	=	xfrm_tunnel_rcv,
+	.err_handler	=	xfrm_tunnel_err,
+	.priority	=	3,
+};
+#endif
+
+static int __init ipip_init(void)
+{
+	if (xfrm_register_type(&ipip_type, AF_INET) < 0) {
+		pr_info("%s: can't add xfrm type\n", __func__);
+		return -EAGAIN;
+	}
+
+	if (xfrm4_tunnel_register(&xfrm_tunnel_handler, AF_INET)) {
+		pr_info("%s: can't add xfrm handler for AF_INET\n", __func__);
+		xfrm_unregister_type(&ipip_type, AF_INET);
+		return -EAGAIN;
+	}
+#if IS_ENABLED(CONFIG_IPV6)
+	if (xfrm4_tunnel_register(&xfrm64_tunnel_handler, AF_INET6)) {
+		pr_info("%s: can't add xfrm handler for AF_INET6\n", __func__);
+		xfrm4_tunnel_deregister(&xfrm_tunnel_handler, AF_INET);
+		xfrm_unregister_type(&ipip_type, AF_INET);
+		return -EAGAIN;
+	}
+#endif
+	return 0;
+}
+
+static void __exit ipip_fini(void)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (xfrm4_tunnel_deregister(&xfrm64_tunnel_handler, AF_INET6))
+		pr_info("%s: can't remove xfrm handler for AF_INET6\n",
+			__func__);
+#endif
+	if (xfrm4_tunnel_deregister(&xfrm_tunnel_handler, AF_INET))
+		pr_info("%s: can't remove xfrm handler for AF_INET\n",
+			__func__);
+	xfrm_unregister_type(&ipip_type, AF_INET);
+}
+
+module_init(ipip_init);
+module_exit(ipip_fini);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_IPIP);