From ffe387740bbe88dd88bbe04d6375902708003d6e Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@nbd.name>
Date: Fri, 7 Jul 2017 17:25:00 +0200
Subject: net: add packet mangeling patch

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 include/linux/netdevice.h | 11 +++++++++++
 include/linux/skbuff.h    | 14 ++++----------
 net/Kconfig               |  6 ++++++
 net/core/dev.c            | 18 ++++++++++++++----
 net/core/skbuff.c         | 17 +++++++++++++++++
 net/ethernet/eth.c        |  6 ++++++
 6 files changed, 58 insertions(+), 14 deletions(-)

--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1412,6 +1412,7 @@ enum netdev_priv_flags {
 	IFF_PHONY_HEADROOM		= 1<<26,
 	IFF_MACSEC			= 1<<27,
 	IFF_L3MDEV_RX_HANDLER		= 1<<28,
+	IFF_NO_IP_ALIGN			= 1<<29,
 };
 
 #define IFF_802_1Q_VLAN			IFF_802_1Q_VLAN
@@ -1442,6 +1443,7 @@ enum netdev_priv_flags {
 #define IFF_RXFH_CONFIGURED		IFF_RXFH_CONFIGURED
 #define IFF_MACSEC			IFF_MACSEC
 #define IFF_L3MDEV_RX_HANDLER		IFF_L3MDEV_RX_HANDLER
+#define IFF_NO_IP_ALIGN			IFF_NO_IP_ALIGN
 
 /**
  *	struct net_device - The DEVICE structure.
@@ -1728,6 +1730,11 @@ struct net_device {
 	const struct xfrmdev_ops *xfrmdev_ops;
 #endif
 
+#ifdef CONFIG_ETHERNET_PACKET_MANGLE
+	void (*eth_mangle_rx)(struct net_device *dev, struct sk_buff *skb);
+	struct sk_buff *(*eth_mangle_tx)(struct net_device *dev, struct sk_buff *skb);
+#endif
+
 	const struct header_ops *header_ops;
 
 	unsigned int		flags;
@@ -1797,6 +1804,10 @@ struct net_device {
 	struct mpls_dev __rcu	*mpls_ptr;
 #endif
 
+#ifdef CONFIG_ETHERNET_PACKET_MANGLE
+	void			*phy_ptr; /* PHY device specific data */
+#endif
+
 /*
  * Cache lines mostly used on receive path (including eth_type_trans())
  */
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2514,6 +2514,10 @@ static inline int pskb_trim(struct sk_bu
 	return (len < skb->len) ? __pskb_trim(skb, len) : 0;
 }
 
+extern struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
+		unsigned int length, gfp_t gfp);
+
+
 /**
  *	pskb_trim_unique - remove end from a paged unique (not cloned) buffer
  *	@skb: buffer to alter
@@ -2645,16 +2649,6 @@ static inline struct sk_buff *dev_alloc_
 }
 
 
-static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
-		unsigned int length, gfp_t gfp)
-{
-	struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
-
-	if (NET_IP_ALIGN && skb)
-		skb_reserve(skb, NET_IP_ALIGN);
-	return skb;
-}
-
 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
 		unsigned int length)
 {
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -25,6 +25,12 @@ menuconfig NET
 
 if NET
 
+config ETHERNET_PACKET_MANGLE
+	bool
+	help
+	  This option can be selected by phy drivers that need to mangle
+	  packets going in or out of an ethernet device.
+
 config WANT_COMPAT_NETLINK_MESSAGES
 	bool
 	help
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3004,10 +3004,20 @@ static int xmit_one(struct sk_buff *skb,
 	if (!list_empty(&ptype_all) || !list_empty(&dev->ptype_all))
 		dev_queue_xmit_nit(skb, dev);
 
-	len = skb->len;
-	trace_net_dev_start_xmit(skb, dev);
-	rc = netdev_start_xmit(skb, dev, txq, more);
-	trace_net_dev_xmit(skb, rc, dev, len);
+#ifdef CONFIG_ETHERNET_PACKET_MANGLE
+	if (!dev->eth_mangle_tx ||
+	    (skb = dev->eth_mangle_tx(dev, skb)) != NULL)
+#else
+	if (1)
+#endif
+	{
+		len = skb->len;
+		trace_net_dev_start_xmit(skb, dev);
+		rc = netdev_start_xmit(skb, dev, txq, more);
+		trace_net_dev_xmit(skb, rc, dev, len);
+	} else {
+		rc = NETDEV_TX_OK;
+	}
 
 	return rc;
 }
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -63,6 +63,7 @@
 #include <linux/errqueue.h>
 #include <linux/prefetch.h>
 #include <linux/if_vlan.h>
+#include <linux/if.h>
 
 #include <net/protocol.h>
 #include <net/dst.h>
@@ -503,6 +504,22 @@ skb_fail:
 }
 EXPORT_SYMBOL(__napi_alloc_skb);
 
+struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
+		unsigned int length, gfp_t gfp)
+{
+	struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
+
+#ifdef CONFIG_ETHERNET_PACKET_MANGLE
+	if (dev && (dev->priv_flags & IFF_NO_IP_ALIGN))
+		return skb;
+#endif
+
+	if (NET_IP_ALIGN && skb)
+		skb_reserve(skb, NET_IP_ALIGN);
+	return skb;
+}
+EXPORT_SYMBOL(__netdev_alloc_skb_ip_align);
+
 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
 		     int size, unsigned int truesize)
 {
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -172,6 +172,12 @@ __be16 eth_type_trans(struct sk_buff *sk
 	const struct ethhdr *eth;
 
 	skb->dev = dev;
+
+#ifdef CONFIG_ETHERNET_PACKET_MANGLE
+	if (dev->eth_mangle_rx)
+		dev->eth_mangle_rx(dev, skb);
+#endif
+
 	skb_reset_mac_header(skb);
 
 	eth = (struct ethhdr *)skb->data;
