Revert "Fix XFRM-I support for nested ESP tunnels"

[ Upstream commit 5fc46f9 ]

This reverts commit b0355db.

The reverted commit clears the secpath on packets received via xfrm interfaces
to support nested IPsec tunnels. This breaks Netfilter policy matching using
xt_policy in the FORWARD chain, as the secpath is missing during forwarding.
Additionally, Benedict Wong reports that it breaks Transport-in-Tunnel mode.

Fix this regression by reverting the commit until we have a better approach
for nested IPsec tunnels.

Fixes: b0355db ("Fix XFRM-I support for nested ESP tunnels")
Link: https://lore.kernel.org/netdev/20230412085615.124791-1-martin@strongswan.org/
Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/xfrm/xfrm_interface.c

@@ -310,52 +310,6 @@ static void xfrmi_scrub_packet(struct sk_buff *skb, bool xnet)
 	skb->mark = 0;
 }
 
-static int xfrmi_input(struct sk_buff *skb, int nexthdr, __be32 spi,
-		       int encap_type, unsigned short family)
-{
-	struct sec_path *sp;
-
-	sp = skb_sec_path(skb);
-	if (sp && (sp->len || sp->olen) &&
-	    !xfrm_policy_check(NULL, XFRM_POLICY_IN, skb, family))
-		goto discard;
-
-	XFRM_SPI_SKB_CB(skb)->family = family;
-	if (family == AF_INET) {
-		XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
-		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
-	} else {
-		XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
-		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
-	}
-
-	return xfrm_input(skb, nexthdr, spi, encap_type);
-discard:
-	kfree_skb(skb);
-	return 0;
-}
-
-static int xfrmi4_rcv(struct sk_buff *skb)
-{
-	return xfrmi_input(skb, ip_hdr(skb)->protocol, 0, 0, AF_INET);
-}
-
-static int xfrmi6_rcv(struct sk_buff *skb)
-{
-	return xfrmi_input(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
-			   0, 0, AF_INET6);
-}
-
-static int xfrmi4_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
-{
-	return xfrmi_input(skb, nexthdr, spi, encap_type, AF_INET);
-}
-
-static int xfrmi6_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
-{
-	return xfrmi_input(skb, nexthdr, spi, encap_type, AF_INET6);
-}
-
 static int xfrmi_rcv_cb(struct sk_buff *skb, int err)
 {
 	const struct xfrm_mode *inner_mode;
@@ -983,8 +937,8 @@ static struct pernet_operations xfrmi_net_ops = {
 };
 
 static struct xfrm6_protocol xfrmi_esp6_protocol __read_mostly = {
-	.handler	=	xfrmi6_rcv,
-	.input_handler	=	xfrmi6_input,
+	.handler	=	xfrm6_rcv,
+	.input_handler	=	xfrm_input,
 	.cb_handler	=	xfrmi_rcv_cb,
 	.err_handler	=	xfrmi6_err,
 	.priority	=	10,
@@ -1034,8 +988,8 @@ static struct xfrm6_tunnel xfrmi_ip6ip_handler __read_mostly = {
 #endif
 
 static struct xfrm4_protocol xfrmi_esp4_protocol __read_mostly = {
-	.handler	=	xfrmi4_rcv,
-	.input_handler	=	xfrmi4_input,
+	.handler	=	xfrm4_rcv,
+	.input_handler	=	xfrm_input,
 	.cb_handler	=	xfrmi_rcv_cb,
 	.err_handler	=	xfrmi4_err,
 	.priority	=	10,

net/xfrm/xfrm_policy.c

@@ -3664,9 +3664,6 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 			goto reject;
 		}
 
-		if (if_id)
-			secpath_reset(skb);
-
 		xfrm_pols_put(pols, npols);
 		return 1;
 	}