[PATCH net-next v3 1/3] net/macsec: Add MACsec skb extension Tx Data path support

[Lior Nahmanson <liorna@nvidia.com>]

In the current MACsec offload implementation, MACsec interfaces are
sharing the same MAC address of their parent interface by default.
Therefore, HW can't distinguish if a packet was sent from MACsec
interface and need to be offloaded or not.
Also, it can't distinguish from which MACsec interface it was sent in
case there are multiple MACsec interface with the same MAC address.

Used SKB extension, so SW can mark if a packet is needed to be offloaded
and use the SCI, which is unique value for each MACsec interface,
to notify the HW from which MACsec interface the packet is sent.

Signed-off-by: Lior Nahmanson <liorna@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Ben Ben-Ishay <benishay@nvidia.com>
---
v1->v2:
- removed offloaded field from struct macsec_ext
v2->v3:
- removed Issue and Change-Id from commit message
---
 drivers/net/Kconfig    | 1 +
 drivers/net/macsec.c   | 4 ++++
 include/linux/skbuff.h | 3 +++
 include/net/macsec.h   | 5 +++++
 net/core/skbuff.c      | 7 +++++++
 5 files changed, 20 insertions(+)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index b2a4f998c180..6c9a950b7010 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -313,6 +313,7 @@ config MACSEC
 	select CRYPTO_AES
 	select CRYPTO_GCM
 	select GRO_CELLS
+	select SKB_EXTENSIONS
 	help
 	   MACsec is an encryption standard for Ethernet.
 
diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index c881e1bf6f6e..9be0606d70da 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -3379,6 +3379,10 @@ static netdev_tx_t macsec_start_xmit(struct sk_buff *skb,
 	int ret, len;
 
 	if (macsec_is_offloaded(netdev_priv(dev))) {
+		struct macsec_ext *secext = skb_ext_add(skb, SKB_EXT_MACSEC);
+
+		secext->sci = secy->sci;
+
 		skb->dev = macsec->real_dev;
 		return dev_queue_xmit(skb);
 	}
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 82edf0359ab3..350693a787ca 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4495,6 +4495,9 @@ enum skb_ext_id {
 #endif
 #if IS_ENABLED(CONFIG_MCTP_FLOWS)
 	SKB_EXT_MCTP,
+#endif
+#if IS_ENABLED(CONFIG_MACSEC)
+	SKB_EXT_MACSEC,
 #endif
 	SKB_EXT_NUM, /* must be last */
 };
diff --git a/include/net/macsec.h b/include/net/macsec.h
index d6fa6b97f6ef..6de49d9c98bc 100644
--- a/include/net/macsec.h
+++ b/include/net/macsec.h
@@ -20,6 +20,11 @@
 typedef u64 __bitwise sci_t;
 typedef u32 __bitwise ssci_t;
 
+/* MACsec sk_buff extension data */
+struct macsec_ext {
+	sci_t sci;
+};
+
 typedef union salt {
 	struct {
 		u32 ssci;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index fec75f8bf1f4..640823b5bd2f 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -72,6 +72,7 @@
 #include <net/mptcp.h>
 #include <net/mctp.h>
 #include <net/page_pool.h>
+#include <net/macsec.h>
 
 #include <linux/uaccess.h>
 #include <trace/events/skb.h>
@@ -4346,6 +4347,9 @@ static const u8 skb_ext_type_len[] = {
 #if IS_ENABLED(CONFIG_MCTP_FLOWS)
 	[SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
 #endif
+#if IS_ENABLED(CONFIG_MACSEC)
+	[SKB_EXT_MACSEC] = SKB_EXT_CHUNKSIZEOF(struct macsec_ext),
+#endif
 };
 
 static __always_inline unsigned int skb_ext_total_length(void)
@@ -4365,6 +4369,9 @@ static __always_inline unsigned int skb_ext_total_length(void)
 #endif
 #if IS_ENABLED(CONFIG_MCTP_FLOWS)
 		skb_ext_type_len[SKB_EXT_MCTP] +
+#endif
+#if IS_ENABLED(CONFIG_MACSEC)
+		skb_ext_type_len[SKB_EXT_MACSEC] +
 #endif
 		0;
 }
-- 
2.25.4