Merge tag 'ipsec-next-2024-07-13' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next

Steffen Klassert says:

====================
pull request (net-next): ipsec-next 2024-07-13

1) Support sending NAT keepalives in ESP in UDP states.
   Userspace IKE daemon had to do this before, but the
   kernel can better keep track of it.
   From Eyal Birger.

2) Support IPsec crypto offload for IPv6 ESP and IPv4 UDP-encapsulated
   ESP data paths. Currently, IPsec crypto offload is enabled for GRO
   code path only. This patchset support UDP encapsulation for the non
   GRO path. From Mike Yu.

* tag 'ipsec-next-2024-07-13' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next:
  xfrm: Support crypto offload for outbound IPv4 UDP-encapsulated ESP packet
  xfrm: Support crypto offload for inbound IPv4 UDP-encapsulated ESP packet
  xfrm: Allow UDP encapsulation in crypto offload control path
  xfrm: Support crypto offload for inbound IPv6 ESP packets not in GRO path
  xfrm: support sending NAT keepalives in ESP in UDP states
====================

Link: https://patch.msgid.link/20240713102416.3272997-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 23 insertions, 2 deletions

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 3968d3f98e08..73981595f062 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -349,6 +349,7 @@ static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
 {
 	struct udphdr *uh;
 	unsigned int len;
+	struct xfrm_offload *xo = xfrm_offload(skb);
 
 	len = skb->len + esp->tailen - skb_transport_offset(skb);
 	if (len + sizeof(struct iphdr) > IP_MAX_MTU)
@@ -360,7 +361,12 @@ static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
 	uh->len = htons(len);
 	uh->check = 0;
 
-	*skb_mac_header(skb) = IPPROTO_UDP;
+	/* For IPv4 ESP with UDP encapsulation, if xo is not null, the skb is in the crypto offload
+	 * data path, which means that esp_output_udp_encap is called outside of the XFRM stack.
+	 * In this case, the mac header doesn't point to the IPv4 protocol field, so don't set it.
+	 */
+	if (!xo || encap_type != UDP_ENCAP_ESPINUDP)
+		*skb_mac_header(skb) = IPPROTO_UDP;
 
 	return (struct ip_esp_hdr *)(uh + 1);
 }
diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index b3271957ad9a..a37d18858c72 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -264,6 +264,7 @@ static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_
 	struct esp_info esp;
 	bool hw_offload = true;
 	__u32 seq;
+	int encap_type = 0;
 
 	esp.inplace = true;
 
@@ -296,8 +297,10 @@ static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_
 
 	esp.esph = ip_esp_hdr(skb);
 
+	if (x->encap)
+		encap_type = x->encap->encap_type;
 
-	if (!hw_offload || !skb_is_gso(skb)) {
+	if (!hw_offload || !skb_is_gso(skb) || (hw_offload && encap_type == UDP_ENCAP_ESPINUDP)) {
 		esp.nfrags = esp_output_head(x, skb, &esp);
 		if (esp.nfrags < 0)
 			return esp.nfrags;
@@ -324,6 +327,18 @@ static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_
 
 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
 
+	if (hw_offload && encap_type == UDP_ENCAP_ESPINUDP) {
+		/* In the XFRM stack, the encapsulation protocol is set to iphdr->protocol by
+		 * setting *skb_mac_header(skb) (see esp_output_udp_encap()) where skb->mac_header
+		 * points to iphdr->protocol (see xfrm4_tunnel_encap_add()).
+		 * However, in esp_xmit(), skb->mac_header doesn't point to iphdr->protocol.
+		 * Therefore, the protocol field needs to be corrected.
+		 */
+		ip_hdr(skb)->protocol = IPPROTO_UDP;
+
+		esph->seq_no = htonl(seq);
+	}
+
 	ip_hdr(skb)->tot_len = htons(skb->len);
 	ip_send_check(ip_hdr(skb));