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

[ Upstream commit 5fc46f94219d1d103ffb5f0832be9da674d85a73 ]

This reverts commit b0355dbbf13c0052931dd14c38c789efed64d3de.

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: b0355dbbf13c ("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>

Bug: 289136405
Bug: 288489934
(cherry picked from commit 288247879f4e7adcbce8a93969e3b48d8944e7a9)
Change-Id: Iefaed6d21a641fefb02e0fd0067086a9ae3a802a
Signed-off-by: Carlos Llamas <cmllamas@google.com>
diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 694eec6..1e8b26e 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -207,52 +207,6 @@
 	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;
@@ -820,8 +774,8 @@
 };
 
 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,
@@ -871,8 +825,8 @@
 #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,
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 0540e9f..ba58b96 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3669,9 +3669,6 @@
 			goto reject;
 		}
 
-		if (if_id)
-			secpath_reset(skb);
-
 		xfrm_pols_put(pols, npols);
 		return 1;
 	}