net: Add framework to allow sending packets with customized CRC.

This is useful for testing RX handling of frames with bad
CRCs.

Requires driver support to actually put the packet on the
wire properly.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

5 files changed, 20 insertions, 2 deletions

diff --git a/include/asm-generic/socket.h b/include/asm-generic/socket.h
index d9aaac0..b1bea03 100644
--- a/include/asm-generic/socket.h
+++ b/include/asm-generic/socket.h
@@ -68,4 +68,8 @@
 #define SO_WIFI_STATUS		41
 #define SCM_WIFI_STATUS	SO_WIFI_STATUS
 #define SO_PEEK_OFF		42
+
+/* Instruct lower device to use last 4-bytes of skb data as FCS */
+#define SO_NOFCS		43
+
 #endif /* __ASM_GENERIC_SOCKET_H */
diff --git a/include/linux/if.h b/include/linux/if.h
index 06b6ef6..f995c66 100644
--- a/include/linux/if.h
+++ b/include/linux/if.h
@@ -80,6 +80,8 @@
 					 * skbs on transmit */
 #define IFF_UNICAST_FLT	0x20000		/* Supports unicast filtering	*/
 #define IFF_TEAM_PORT	0x40000		/* device used as team port */
+#define IFF_SUPP_NOFCS	0x80000		/* device supports sending custom FCS */
+
 
 #define IF_GET_IFACE	0x0001		/* for querying only */
 #define IF_GET_PROTO	0x0002
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0eac07c..f1b7d03 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1082,7 +1082,8 @@ struct net_device {
 	const struct header_ops *header_ops;
 
 	unsigned int		flags;	/* interface flags (a la BSD)	*/
-	unsigned int		priv_flags; /* Like 'flags' but invisible to userspace. */
+	unsigned int		priv_flags; /* Like 'flags' but invisible to userspace.
+					     * See if.h for definitions. */
 	unsigned short		gflags;
 	unsigned short		padded;	/* How much padding added by alloc_netdev() */
 
@@ -2650,6 +2651,11 @@ static inline int netif_is_bond_slave(struct net_device *dev)
 	return dev->flags & IFF_SLAVE && dev->priv_flags & IFF_BONDING;
 }
 
+static inline bool netif_supports_nofcs(struct net_device *dev)
+{
+	return dev->priv_flags & IFF_SUPP_NOFCS;
+}
+
 extern struct pernet_operations __net_initdata loopback_net_ops;
 
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c11a44e..06a4c0f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -361,6 +361,7 @@ typedef unsigned char *sk_buff_data_t;
  *		ports.
  *	@wifi_acked_valid: wifi_acked was set
  *	@wifi_acked: whether frame was acked on wifi or not
+ *	@no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
  *	@dma_cookie: a cookie to one of several possible DMA operations
  *		done by skb DMA functions
  *	@secmark: security marking
@@ -459,7 +460,8 @@ struct sk_buff {
 	__u8			l4_rxhash:1;
 	__u8			wifi_acked_valid:1;
 	__u8			wifi_acked:1;
-	/* 10/12 bit hole (depending on ndisc_nodetype presence) */
+	__u8			no_fcs:1;
+	/* 9/11 bit hole (depending on ndisc_nodetype presence) */
 	kmemcheck_bitfield_end(flags2);
 
 #ifdef CONFIG_NET_DMA
diff --git a/include/net/sock.h b/include/net/sock.h
index 9c0553b..ba761e7 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -615,6 +615,10 @@ enum sock_flags {
 	SOCK_RXQ_OVFL,
 	SOCK_ZEROCOPY, /* buffers from userspace */
 	SOCK_WIFI_STATUS, /* push wifi status to userspace */
+	SOCK_NOFCS, /* Tell NIC not to do the Ethernet FCS.
+		     * Will use last 4 bytes of packet sent from
+		     * user-space instead.
+		     */
 };
 
 static inline void sock_copy_flags(struct sock *nsk, struct sock *osk)