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 d9aaac0c36d4..b1bea03274d5 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 06b6ef60c821..f995c663c493 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 0eac07c95255..f1b7d037c2c5 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 c11a44ea1bf4..06a4c0fd7bef 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 9c0553b9e451..ba761e7de252 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)