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>

arch/alpha/include/asm/socket.h

@@ -73,6 +73,9 @@
 #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
+
 /* O_NONBLOCK clashes with the bits used for socket types.  Therefore we
  * have to define SOCK_NONBLOCK to a different value here.
  */

arch/arm/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_SOCKET_H */

arch/avr32/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_AVR32_SOCKET_H */

arch/cris/include/asm/socket.h

@@ -68,6 +68,9 @@
 #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_SOCKET_H */
 
 

arch/frv/include/asm/socket.h

@@ -66,5 +66,8 @@
 #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_SOCKET_H */
 

arch/h8300/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_SOCKET_H */

arch/ia64/include/asm/socket.h

@@ -75,4 +75,7 @@
 #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_IA64_SOCKET_H */

arch/m32r/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_M32R_SOCKET_H */

arch/m68k/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_SOCKET_H */

arch/mips/include/asm/socket.h

@@ -86,6 +86,9 @@ To add: #define SO_REUSEPORT 0x0200	/* Allow local address and port reuse.  */
 #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
+
 #ifdef __KERNEL__
 
 /** sock_type - Socket types

arch/mn10300/include/asm/socket.h

@@ -66,4 +66,7 @@
 #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_SOCKET_H */

arch/parisc/include/asm/socket.h

@@ -65,6 +65,10 @@
 #define SCM_WIFI_STATUS		SO_WIFI_STATUS
 #define SO_PEEK_OFF		0x4023
 
+/* Instruct lower device to use last 4-bytes of skb data as FCS */
+#define SO_NOFCS		0x4024
+
+
 /* O_NONBLOCK clashes with the bits used for socket types.  Therefore we
  * have to define SOCK_NONBLOCK to a different value here.
  */

arch/powerpc/include/asm/socket.h

@@ -73,4 +73,7 @@
 #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_POWERPC_SOCKET_H */

arch/s390/include/asm/socket.h

@@ -74,4 +74,7 @@
 #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_SOCKET_H */

arch/sparc/include/asm/socket.h

@@ -62,6 +62,10 @@
 #define SCM_WIFI_STATUS		SO_WIFI_STATUS
 #define SO_PEEK_OFF		0x0026
 
+/* Instruct lower device to use last 4-bytes of skb data as FCS */
+#define SO_NOFCS		0x0027
+
+
 /* Security levels - as per NRL IPv6 - don't actually do anything */
 #define SO_SECURITY_AUTHENTICATION		0x5001
 #define SO_SECURITY_ENCRYPTION_TRANSPORT	0x5002

arch/xtensa/include/asm/socket.h

@@ -77,4 +77,7 @@
 #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	/* _XTENSA_SOCKET_H */

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 */

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

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. */

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

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)

net/core/skbuff.c

@@ -592,6 +592,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	new->rxhash		= old->rxhash;
 	new->ooo_okay		= old->ooo_okay;
 	new->l4_rxhash		= old->l4_rxhash;
+	new->no_fcs		= old->no_fcs;
 #ifdef CONFIG_XFRM
 	new->sp			= secpath_get(old->sp);
 #endif

net/core/sock.c

@@ -799,6 +799,11 @@ set_rcvbuf:
 		else
 			ret = -EOPNOTSUPP;
 		break;
+
+	case SO_NOFCS:
+		sock_valbool_flag(sk, SOCK_NOFCS, valbool);
+		break;
+
 	default:
 		ret = -ENOPROTOOPT;
 		break;

net/packet/af_packet.c

@@ -1459,6 +1459,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock,
 	struct net_device *dev;
 	__be16 proto = 0;
 	int err;
+	int extra_len = 0;
 
 	/*
 	 *	Get and verify the address.
@@ -1493,8 +1494,16 @@ retry:
 	 * raw protocol and you must do your own fragmentation at this level.
 	 */
 
+	if (unlikely(sock_flag(sk, SOCK_NOFCS))) {
+		if (!netif_supports_nofcs(dev)) {
+			err = -EPROTONOSUPPORT;
+			goto out_unlock;
+		}
+		extra_len = 4; /* We're doing our own CRC */
+	}
+
 	err = -EMSGSIZE;
-	if (len > dev->mtu + dev->hard_header_len + VLAN_HLEN)
+	if (len > dev->mtu + dev->hard_header_len + VLAN_HLEN + extra_len)
 		goto out_unlock;
 
 	if (!skb) {
@@ -1526,7 +1535,7 @@ retry:
 		goto retry;
 	}
 
-	if (len > (dev->mtu + dev->hard_header_len)) {
+	if (len > (dev->mtu + dev->hard_header_len + extra_len)) {
 		/* Earlier code assumed this would be a VLAN pkt,
 		 * double-check this now that we have the actual
 		 * packet in hand.
@@ -1548,6 +1557,9 @@ retry:
 	if (err < 0)
 		goto out_unlock;
 
+	if (unlikely(extra_len == 4))
+		skb->no_fcs = 1;
+
 	dev_queue_xmit(skb);
 	rcu_read_unlock();
 	return len;
@@ -2209,6 +2221,7 @@ static int packet_snd(struct socket *sock,
 	struct packet_sock *po = pkt_sk(sk);
 	unsigned short gso_type = 0;
 	int hlen, tlen;
+	int extra_len = 0;
 
 	/*
 	 *	Get and verify the address.
@@ -2288,8 +2301,16 @@ static int packet_snd(struct socket *sock,
 		}
 	}
 
+	if (unlikely(sock_flag(sk, SOCK_NOFCS))) {
+		if (!netif_supports_nofcs(dev)) {
+			err = -EPROTONOSUPPORT;
+			goto out_unlock;
+		}
+		extra_len = 4; /* We're doing our own CRC */
+	}
+
 	err = -EMSGSIZE;
-	if (!gso_type && (len > dev->mtu + reserve + VLAN_HLEN))
+	if (!gso_type && (len > dev->mtu + reserve + VLAN_HLEN + extra_len))
 		goto out_unlock;
 
 	err = -ENOBUFS;
@@ -2315,7 +2336,7 @@ static int packet_snd(struct socket *sock,
 	if (err < 0)
 		goto out_free;
 
-	if (!gso_type && (len > dev->mtu + reserve)) {
+	if (!gso_type && (len > dev->mtu + reserve + extra_len)) {
 		/* Earlier code assumed this would be a VLAN pkt,
 		 * double-check this now that we have the actual
 		 * packet in hand.
@@ -2353,6 +2374,9 @@ static int packet_snd(struct socket *sock,
 		len += vnet_hdr_len;
 	}
 
+	if (unlikely(extra_len == 4))
+		skb->no_fcs = 1;
+
 	/*
 	 *	Now send it
 	 */