net: Support RX-ALL feature flag.

This flag requests that network devices pass all
received frames up the stack, even ones with errors
such as invalid FCS (frame check sum).  This will
allow sniffers to see bad packets and perhaps
give the user some idea how to fix the problem.

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>

Documentation/networking/netdev-features.txt

@@ -158,3 +158,10 @@ VLANs. This may be not useful, though.]
 This requests that the NIC append the Ethernet Frame Checksum (FCS)
 to the end of the skb data.  This allows sniffers and other tools to
 read the CRC recorded by the NIC on receipt of the packet.
+
+*  rx-all
+
+This requests that the NIC receive all possible frames, including errored
+frames (such as bad FCS, etc).  This can be helpful when sniffing a link with
+bad packets on it.  Some NICs may receive more packets if also put into normal
+PROMISC mdoe.

include/linux/netdev_features.h

@@ -55,6 +55,7 @@ enum {
 	NETIF_F_NOCACHE_COPY_BIT,	/* Use no-cache copyfromuser */
 	NETIF_F_LOOPBACK_BIT,		/* Enable loopback */
 	NETIF_F_RXFCS_BIT,		/* Append FCS to skb pkt data */
+	NETIF_F_RXALL_BIT,		/* Receive errored frames too */
 
 	/*
 	 * Add your fresh new feature above and remember to update
@@ -100,6 +101,7 @@ enum {
 #define NETIF_F_UFO		__NETIF_F(UFO)
 #define NETIF_F_VLAN_CHALLENGED	__NETIF_F(VLAN_CHALLENGED)
 #define NETIF_F_RXFCS		__NETIF_F(RXFCS)
+#define NETIF_F_RXALL		__NETIF_F(RXALL)
 
 /* Features valid for ethtool to change */
 /* = all defined minus driver/device-class-related */

net/core/ethtool.c

@@ -74,6 +74,7 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN]
 	[NETIF_F_NOCACHE_COPY_BIT] =     "tx-nocache-copy",
 	[NETIF_F_LOOPBACK_BIT] =         "loopback",
 	[NETIF_F_RXFCS_BIT] =            "rx-fcs",
+	[NETIF_F_RXALL_BIT] =            "rx-all",
 };
 
 static int ethtool_get_features(struct net_device *dev, void __user *useraddr)