xfrm: Fix double ESP trailer insertion in IPsec crypto offload.

[ Upstream commit 94579ac3f6d0820adc83b5dc5358ead0158101e9 ]

During IPsec performance testing, we see bad ICMP checksum. The error packet
has duplicated ESP trailer due to double validate_xmit_xfrm calls. The first call
is from ip_output, but the packet cannot be sent because
netif_xmit_frozen_or_stopped is true and the packet gets dev_requeue_skb. The second
call is from NET_TX softirq. However after the first call, the packet already
has the ESP trailer.

Fix by marking the skb with XFRM_XMIT bit after the packet is handled by
validate_xmit_xfrm to avoid duplicate ESP trailer insertion.

Fixes: f6e27114a60a ("net: Add a xfrm validate function to validate_xmit_skb")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Reviewed-by: Boris Pismenny <borisp@mellanox.com>
Reviewed-by: Raed Salem <raeds@mellanox.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 48dc1ce..f087c8d 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1083,6 +1083,7 @@
 #define	XFRM_GRO		32
 #define	XFRM_ESP_NO_TRAILER	64
 #define	XFRM_DEV_RESUME		128
+#define	XFRM_XMIT		256
 
 	__u32			status;
 #define CRYPTO_SUCCESS				1