Merge tag 'ipsec-2024-05-02' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec

Steffen Klassert says:

====================
pull request (net): ipsec 2024-05-02

1) Fix an error pointer dereference in xfrm_in_fwd_icmp.
   From Antony Antony.

2) Preserve vlan tags for ESP transport mode software GRO.
   From Paul Davey.

3) Fix a spelling mistake in an uapi xfrm.h comment.
   From Anotny Antony.

* tag 'ipsec-2024-05-02' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec:
  xfrm: Correct spelling mistake in xfrm.h comment
  xfrm: Preserve vlan tags for transport mode software GRO
  xfrm: fix possible derferencing in error path
====================

Link: https://lore.kernel.org/r/20240502084838.2269355-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 20 insertions, 2 deletions

diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index dae35101d189..86382e08140e 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -63,7 +63,11 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async)
 	ip_send_check(iph);
 
 	if (xo && (xo->flags & XFRM_GRO)) {
-		skb_mac_header_rebuild(skb);
+		/* The full l2 header needs to be preserved so that re-injecting the packet at l2
+		 * works correctly in the presence of vlan tags.
+		 */
+		skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
+		skb_reset_network_header(skb);
 		skb_reset_transport_header(skb);
 		return 0;
 	}
diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c
index a17d783dc7c0..c6b8e132e10a 100644
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -58,7 +58,11 @@ int xfrm6_transport_finish(struct sk_buff *skb, int async)
 	skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
 
 	if (xo && (xo->flags & XFRM_GRO)) {
-		skb_mac_header_rebuild(skb);
+		/* The full l2 header needs to be preserved so that re-injecting the packet at l2
+		 * works correctly in the presence of vlan tags.
+		 */
+		skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
+		skb_reset_network_header(skb);
 		skb_reset_transport_header(skb);
 		return 0;
 	}
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 161f535c8b94..3a2982a72a6b 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -389,11 +389,15 @@ static int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
  */
 static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 {
+	struct xfrm_offload *xo = xfrm_offload(skb);
 	int ihl = skb->data - skb_transport_header(skb);
 
 	if (skb->transport_header != skb->network_header) {
 		memmove(skb_transport_header(skb),
 			skb_network_header(skb), ihl);
+		if (xo)
+			xo->orig_mac_len =
+				skb_mac_header_was_set(skb) ? skb_mac_header_len(skb) : 0;
 		skb->network_header = skb->transport_header;
 	}
 	ip_hdr(skb)->tot_len = htons(skb->len + ihl);
@@ -404,11 +408,15 @@ static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 #if IS_ENABLED(CONFIG_IPV6)
+	struct xfrm_offload *xo = xfrm_offload(skb);
 	int ihl = skb->data - skb_transport_header(skb);
 
 	if (skb->transport_header != skb->network_header) {
 		memmove(skb_transport_header(skb),
 			skb_network_header(skb), ihl);
+		if (xo)
+			xo->orig_mac_len =
+				skb_mac_header_was_set(skb) ? skb_mac_header_len(skb) : 0;
 		skb->network_header = skb->transport_header;
 	}
 	ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 6affe5cd85d8..53d8fabfa685 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3593,6 +3593,8 @@ xfrm_policy *xfrm_in_fwd_icmp(struct sk_buff *skb,
 			return pol;
 
 		pol = xfrm_policy_lookup(net, &fl1, family, XFRM_POLICY_FWD, if_id);
+		if (IS_ERR(pol))
+			pol = NULL;
 	}
 
 	return pol;