[RFC v5] CAN FD support

* [RFC v5] CAN FD support
@ 2012-05-28 20:02 Oliver Hartkopp
  2012-06-11 14:26 ` Wolfgang Grandegger
  0 siblings, 1 reply; 5+ messages in thread
From: Oliver Hartkopp @ 2012-05-28 20:02 UTC (permalink / raw)
  To: linux-can

Hi all,

since RFC v4 - see http://marc.info/?l=linux-can&m=133708871921901&w=2 from
2012-05-15 - i cleaned up some details and added the support of simultaneous
CAN and CANFD frame handling inside the networking code after some discussion
with Kurt. Sometimes code needs to be implemented to see that there is a more
elegant solution out there when removing that code again ;-)

If you also feel fine with this patch i would finally create a patchset of
four patches, like 

- adding new structures and constants
- adding CAN FD support in af_can.c
- adding CAN FD support in raw.c
- adding CAN FD support in vcan.c

for the upcoming net-next bound for Linux 3.6 .

Some words about the basic concepts of this CAN FD support for Linux CAN
networking. In general the new CAN FD controllers support two different
bitrates for the arbitration phase and the payload phase of the CAN FD frame
and up to 64 bytes of payload. This extended payload length breaks all the
kernel interfaces (ABI) which heavily rely on the CAN frame with fixed eight
bytes of payload (struct can_frame) like the CAN_RAW socket.

This patch enables the CAN network layer to handle CAN FD frames and 'legacy'
CAN frames following ISO 11898-1 and updates the virtual CAN driver (vcan) to
be able to develop and test userspace applications and CAN network drivers.

Main concepts:

1. Introduction of a new data structure canfd_frame with 64 bytes of payload:
   The struct canfd_frame and the existing struct can_frame have the CAN ID
   and the payload length at the same offset inside their structures. This
   allows to change the internal processing of the payload length to a plain
   length handling with values from 0 .. 64 instead of the 'data length code'
   which was a 1:1 mapping in the legacy CAN frames anyway.
   The data length to DLC mapping is only performed inside the CAN drivers,
   preferably with the new helper functions can_dlc2len() and can_len2dlc().

2. The CAN netdevice drivers can be distinguished by the maximum transfer unit
   (MTU), which presents the length of the struct can(fd)_frame:

   MTU = 16 (CAN_MTU)   => sizeof(struct can_frame)   => 'legacy' CAN device 
   MTU = 72 (CANFD_MTU) => sizeof(struct canfd_frame) => CAN FD capable dev

   CAN FD capable devices can also handle and send legacy CAN frames.

3. The internal socket buffers (skbuffs) that contain CAN frames are split in
   two different ethernet frame types to distinguish the frame types e.g. for
   networking tools using AF_PACKET:

   ETH_P_CAN   (val 0x000C): skbuffs containing a struct can_frame
   ETH_P_CANFD (val 0x000D): skbuffs containing a struct canfd_frame

   Inside the CAN network layer the different CAN frame types are
   distinguished by the skbuffs length (skb->len) and not by the
   ETH_P_CAN(FD) protocol tags.

4. CAN FD support in CAN_RAW sockets can be enabled with a new socket option
   CAN_RAW_FD_FRAMES which is off by default. When the new socket option is
   not supported by the CAN_RAW socket (e.g. on older kernels), switching the
   CAN_RAW_FD_FRAMES option returns the error -ENOPROTOOPT.
   Once CAN_RAW_FD_FRAMES is enabled the application can send both CAN frames
   and CAN FD frames. OTOH the application has to handle CAN and CAN FD frames
   when reading from the socket. E.g. when reading with size CANFD_MTU returns
   CAN_MTU bytes that have been received from the socket a legacy CAN frame
   has been read into the provided CAN FD structure. As this frame has a
   payload length <= 8 and has a similar layout the CAN data can be used
   inside the struct canfd_frame as-is.

   As long as the payload length is <=8 the received CAN frames from CAN FD
   capable CAN devices can be received and read by legacy sockets too.
   When user-generated CAN FD frames have a payload length <=8 these can be
   send by legacy CAN network interfaces too.

   CAN_RAW_FD_FRAMES enabled:  CAN_MTU and CANFD_MTU are allowed
   CAN_RAW_FD_FRAMES disabled: only CAN_MTU is allowed (default)

   Sending CAN FD frames with payload length > 8 to a legacy CAN network
   interface returns an -EMSGSIZE error.

I hope this description makes the review of the following patch easier.
I did some conversions to some of the can-utils for private testing:
https://gitorious.org/~hartkopp/linux-can/hartkopps-can-utils


The following diff was generated by 'git diff fb7944b' on the repository

https://gitorious.org/~hartkopp/linux-can/hartkopps-linux-can-next

Regards,
Oliver


 drivers/net/can/dev.c    |   35 +++++++++++++-
 drivers/net/can/vcan.c   |   27 ++++++++--
 include/linux/can.h      |   55 ++++++++++++++++++++--
 include/linux/can/core.h |    4 -
 include/linux/can/dev.h  |   33 ++++++++++---
 include/linux/can/raw.h  |    3 -
 include/linux/if_ether.h |    3 -
 net/can/af_can.c         |  116 ++++++++++++++++++++++++++++++++++++-----------
 net/can/raw.c            |   50 ++++++++++++++++++--
 9 files changed, 271 insertions(+), 55 deletions(-)

---

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index f03d7a4..e1769b5 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -33,6 +33,39 @@ MODULE_DESCRIPTION(MOD_DESC);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
 
+/* CAN DLC to real data length conversion helpers */
+
+static const u8 dlc2len[] = {0, 1, 2, 3, 4, 5, 6, 7,
+			     8, 12, 16, 20, 24, 32, 48, 64};
+
+/* get data length from can_dlc with sanitized can_dlc */
+u8 can_dlc2len(u8 can_dlc)
+{
+	return dlc2len[can_dlc & 0x0F];
+}
+EXPORT_SYMBOL_GPL(can_dlc2len);
+
+static const u8 len2dlc[] = {0, 1, 2, 3, 4, 5, 6, 7, 8,		/* 0 - 8 */
+			     9, 9, 9, 9,			/* 9 - 12 */
+			     10, 10, 10, 10,			/* 13 - 16 */
+			     11, 11, 11, 11,			/* 17 - 20 */
+			     12, 12, 12, 12,			/* 21 - 24 */
+			     13, 13, 13, 13, 13, 13, 13, 13,	/* 25 - 32 */
+			     14, 14, 14, 14, 14, 14, 14, 14,	/* 33 - 40 */
+			     14, 14, 14, 14, 14, 14, 14, 14,	/* 41 - 48 */
+			     15, 15, 15, 15, 15, 15, 15, 15,	/* 49 - 56 */
+			     15, 15, 15, 15, 15, 15, 15, 15};	/* 57 - 64 */
+
+/* map the sanitized data length to an appropriate data length code */ 
+u8 can_len2dlc(u8 len)
+{
+	if (unlikely(len > 64))
+		return 0xF;
+
+	return len2dlc[len];
+}
+EXPORT_SYMBOL_GPL(can_len2dlc);
+
 #ifdef CONFIG_CAN_CALC_BITTIMING
 #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
 
@@ -454,7 +487,7 @@ EXPORT_SYMBOL_GPL(can_bus_off);
 static void can_setup(struct net_device *dev)
 {
 	dev->type = ARPHRD_CAN;
-	dev->mtu = sizeof(struct can_frame);
+	dev->mtu = CAN_MTU;
 	dev->hard_header_len = 0;
 	dev->addr_len = 0;
 	dev->tx_queue_len = 10;
diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c
index ea2d942..4f93c0b 100644
--- a/drivers/net/can/vcan.c
+++ b/drivers/net/can/vcan.c
@@ -70,13 +70,12 @@ MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
 
 static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
 {
-	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 	struct net_device_stats *stats = &dev->stats;
 
 	stats->rx_packets++;
-	stats->rx_bytes += cf->can_dlc;
+	stats->rx_bytes += cfd->len;
 
-	skb->protocol  = htons(ETH_P_CAN);
 	skb->pkt_type  = PACKET_BROADCAST;
 	skb->dev       = dev;
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
@@ -86,7 +85,7 @@ static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
 
 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 {
-	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 	struct net_device_stats *stats = &dev->stats;
 	int loop;
 
@@ -94,7 +93,7 @@ static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_OK;
 
 	stats->tx_packets++;
-	stats->tx_bytes += cf->can_dlc;
+	stats->tx_bytes += cfd->len;
 
 	/* set flag whether this packet has to be looped back */
 	loop = skb->pkt_type == PACKET_LOOPBACK;
@@ -108,7 +107,7 @@ static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 			 * CAN core already did the echo for us
 			 */
 			stats->rx_packets++;
-			stats->rx_bytes += cf->can_dlc;
+			stats->rx_bytes += cfd->len;
 		}
 		kfree_skb(skb);
 		return NETDEV_TX_OK;
@@ -133,14 +132,28 @@ static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 }
 
+static int vcan_change_mtu(struct net_device *dev, int new_mtu)
+{
+	/* Do not allow changing the MTU while running */
+	if (dev->flags & IFF_UP)
+		return -EBUSY;
+
+	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
+		return -EINVAL;
+
+	dev->mtu = new_mtu;
+	return 0;
+}
+
 static const struct net_device_ops vcan_netdev_ops = {
 	.ndo_start_xmit = vcan_tx,
+	.ndo_change_mtu = vcan_change_mtu,
 };
 
 static void vcan_setup(struct net_device *dev)
 {
 	dev->type		= ARPHRD_CAN;
-	dev->mtu		= sizeof(struct can_frame);
+	dev->mtu		= CAN_MTU;
 	dev->hard_header_len	= 0;
 	dev->addr_len		= 0;
 	dev->tx_queue_len	= 0;
diff --git a/include/linux/can.h b/include/linux/can.h
index 9a19bcb..5c80dbd 100644
--- a/include/linux/can.h
+++ b/include/linux/can.h
@@ -46,18 +46,65 @@ typedef __u32 canid_t;
  */
 typedef __u32 can_err_mask_t;
 
+#define CAN_MAX_DLC 8
+#define CAN_MAX_DLEN 8
+
+#define CANFD_MAX_DLC 15
+#define CANFD_MAX_DLEN 64
+
 /**
  * struct can_frame - basic CAN frame structure
- * @can_id:  the CAN ID of the frame and CAN_*_FLAG flags, see above.
- * @can_dlc: the data length field of the CAN frame
- * @data:    the CAN frame payload.
+ * @can_id:  CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
+ * @can_dlc: frame payload length in byte (0 .. 8) aka data length code
+ *           N.B. the DLC field from ISO 11898-1 Chapter 8.4.2.3 has a 1:1
+ *           mapping of the 'data length code' to the real payload length
+ * @data:    CAN frame payload (up to 8 byte)
  */
 struct can_frame {
 	canid_t can_id;  /* 32 bit CAN_ID + EFF/RTR/ERR flags */
-	__u8    can_dlc; /* data length code: 0 .. 8 */
+	__u8    can_dlc; /* frame payload length in byte (0 .. 8) */
 	__u8    data[8] __attribute__((aligned(8)));
 };
 
+/*
+ * defined bits for canfd_frame.flags
+ *
+ * As the default for CAN FD should be to support the high data rate in the
+ * payload section of the frame (HDR) and to support up to 64 byte in the
+ * data section (EDL) the bits are only set in the non-default case.
+ * Btw. as long as there's no real implementation for CAN FD network driver
+ * these bits are only preliminary.
+ *
+ * RX: NOHDR/NOEDL - info about received CAN FD frame
+ *     ESI         - bit from originating CAN controller
+ * TX: NOHDR/NOEDL - control per-frame settings if supported by CAN controller
+ *     ESI         - bit is set by local CAN controller
+ */
+#define CANFD_NOHDR 0x01 /* frame without high data rate */
+#define CANFD_NOEDL 0x02 /* frame without extended data length */
+#define CANFD_ESI   0x04 /* error state indicator */
+
+/**
+ * struct canfd_frame - CAN flexible data rate frame structure
+ * @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
+ * @len:    frame payload length in byte (0 .. 64)
+ * @flags:  additional flags for CAN FD
+ * @__res0: reserved / padding
+ * @__res1: reserved / padding
+ * @data:   CAN FD frame payload (up to 64 byte)
+ */
+struct canfd_frame {
+	canid_t can_id;  /* 32 bit CAN_ID + EFF/RTR/ERR flags */
+	__u8    len;     /* frame payload length in byte (0 .. 64) */
+	__u8    flags;   /* additional flags for CAN FD */
+	__u8    __res0;  /* reserved / padding */
+	__u8    __res1;  /* reserved / padding */
+	__u8    data[64] __attribute__((aligned(8)));
+};
+
+#define CAN_MTU		(sizeof(struct can_frame))
+#define CANFD_MTU	(sizeof(struct canfd_frame))
+
 /* particular protocols of the protocol family PF_CAN */
 #define CAN_RAW		1 /* RAW sockets */
 #define CAN_BCM		2 /* Broadcast Manager */
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 0ccc1cd..78c6c52 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -17,10 +17,10 @@
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 
-#define CAN_VERSION "20090105"
+#define CAN_VERSION "20120528"
 
 /* increment this number each time you change some user-space interface */
-#define CAN_ABI_VERSION "8"
+#define CAN_ABI_VERSION "9"
 
 #define CAN_VERSION_STRING "rev " CAN_VERSION " abi " CAN_ABI_VERSION
 
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 5d2efe7..5e1362f 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -61,23 +61,40 @@ struct can_priv {
  * To be used in the CAN netdriver receive path to ensure conformance with
  * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
  */
-#define get_can_dlc(i)	(min_t(__u8, (i), 8))
+#define get_can_dlc(i)		(min_t(__u8, (i), CAN_MAX_DLC))
+#define get_canfd_dlc(i)	(min_t(__u8, (i), CANFD_MAX_DLC))
 
 /* Drop a given socketbuffer if it does not contain a valid CAN frame. */
 static inline int can_dropped_invalid_skb(struct net_device *dev,
 					  struct sk_buff *skb)
 {
-	const struct can_frame *cf = (struct can_frame *)skb->data;
-
-	if (unlikely(skb->len != sizeof(*cf) || cf->can_dlc > 8)) {
-		kfree_skb(skb);
-		dev->stats.tx_dropped++;
-		return 1;
-	}
+	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (skb->protocol == htons(ETH_P_CAN)) {
+		if (unlikely(skb->len != CAN_MTU ||
+			     cfd->len > CAN_MAX_DLEN))
+			goto inval_skb;
+	} else if (skb->protocol == htons(ETH_P_CANFD)) {
+		if (unlikely(skb->len != CANFD_MTU ||
+			     cfd->len > CANFD_MAX_DLEN))
+			goto inval_skb;
+	} else
+		goto inval_skb;
 
 	return 0;
+
+inval_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return 1;
 }
 
+/* get data length from can_dlc with sanitized can_dlc */
+u8 can_dlc2len(u8 can_dlc);
+
+/* map the sanitized data length to an appropriate data length code */ 
+u8 can_len2dlc(u8 len);
+
 struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max);
 void free_candev(struct net_device *dev);
 
diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
index 781f3a3..a814062 100644
--- a/include/linux/can/raw.h
+++ b/include/linux/can/raw.h
@@ -23,7 +23,8 @@ enum {
 	CAN_RAW_FILTER = 1,	/* set 0 .. n can_filter(s)          */
 	CAN_RAW_ERR_FILTER,	/* set filter for error frames       */
 	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
-	CAN_RAW_RECV_OWN_MSGS	/* receive my own msgs (default:off) */
+	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
+	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
 };
 
 #endif
diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 56d907a..260138b 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -105,7 +105,8 @@
 #define ETH_P_WAN_PPP   0x0007          /* Dummy type for WAN PPP frames*/
 #define ETH_P_PPP_MP    0x0008          /* Dummy type for PPP MP frames */
 #define ETH_P_LOCALTALK 0x0009		/* Localtalk pseudo type 	*/
-#define ETH_P_CAN	0x000C		/* Controller Area Network      */
+#define ETH_P_CAN	0x000C		/* Controller Area Network (CAN)*/
+#define ETH_P_CANFD	0x000D		/* CAN FD 64 byte payload frames*/
 #define ETH_P_PPPTALK	0x0010		/* Dummy type for Atalk over PPP*/
 #define ETH_P_TR_802_2	0x0011		/* 802.2 frames 		*/
 #define ETH_P_MOBITEX	0x0015		/* Mobitex (kaz@cafe.net)	*/
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 0ce2ad0..cc3eb96 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -41,6 +41,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/stddef.h>
 #include <linux/init.h>
 #include <linux/kmod.h>
 #include <linux/slab.h>
@@ -220,30 +221,46 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
  *  -ENOBUFS on full driver queue (see net_xmit_errno())
  *  -ENOMEM when local loopback failed at calling skb_clone()
  *  -EPERM when trying to send on a non-CAN interface
+ *  -EMSGSIZE CAN frame size is bigger than CAN interface MTU
  *  -EINVAL when the skb->data does not contain a valid CAN frame
  */
 int can_send(struct sk_buff *skb, int loop)
 {
 	struct sk_buff *newskb = NULL;
-	struct can_frame *cf = (struct can_frame *)skb->data;
-	int err;
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+	int err = -EINVAL;
+
+	if (skb->len == CAN_MTU) {
+		skb->protocol = htons(ETH_P_CAN);
+		if (unlikely(cfd->len > CAN_MAX_DLEN))
+			goto inval_skb;
+	} else if (skb->len == CANFD_MTU) {
+		skb->protocol = htons(ETH_P_CANFD);
+		if (unlikely(cfd->len > CANFD_MAX_DLEN))
+			goto inval_skb;
+	} else
+		goto inval_skb;
 
-	if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) {
-		kfree_skb(skb);
-		return -EINVAL;
+	/*
+	 * Make sure the CAN frame can pass the selected CAN netdevice.
+	 * As structs can_frame and canfd_frame are similar, we can provide
+	 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
+	 */
+	if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
+		err = -EMSGSIZE;
+		goto inval_skb;
 	}
 
-	if (skb->dev->type != ARPHRD_CAN) {
-		kfree_skb(skb);
-		return -EPERM;
+	if (unlikely(skb->dev->type != ARPHRD_CAN)) {
+		err = -EPERM;
+		goto inval_skb;
 	}
 
-	if (!(skb->dev->flags & IFF_UP)) {
-		kfree_skb(skb);
-		return -ENETDOWN;
+	if (unlikely(!(skb->dev->flags & IFF_UP))) {
+		err = -ENETDOWN;
+		goto inval_skb;
 	}
 
-	skb->protocol = htons(ETH_P_CAN);
 	skb_reset_network_header(skb);
 	skb_reset_transport_header(skb);
 
@@ -300,6 +317,10 @@ int can_send(struct sk_buff *skb, int loop)
 	can_stats.tx_frames_delta++;
 
 	return 0;
+
+inval_skb:
+	kfree_skb(skb);
+	return err;
 }
 EXPORT_SYMBOL(can_send);
 
@@ -632,24 +653,11 @@ static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
 	return matches;
 }
 
-static int can_rcv(struct sk_buff *skb, struct net_device *dev,
-		   struct packet_type *pt, struct net_device *orig_dev)
+static void can_receive(struct sk_buff *skb, struct net_device *dev)
 {
 	struct dev_rcv_lists *d;
-	struct can_frame *cf = (struct can_frame *)skb->data;
 	int matches;
 
-	if (!net_eq(dev_net(dev), &init_net))
-		goto drop;
-
-	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
-		      skb->len != sizeof(struct can_frame) ||
-		      cf->can_dlc > 8,
-		      "PF_CAN: dropped non conform skbuf: "
-		      "dev type %d, len %d, can_dlc %d\n",
-		      dev->type, skb->len, cf->can_dlc))
-		goto drop;
-
 	/* update statistics */
 	can_stats.rx_frames++;
 	can_stats.rx_frames_delta++;
@@ -673,7 +681,49 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 		can_stats.matches++;
 		can_stats.matches_delta++;
 	}
+}
 
+static int can_rcv(struct sk_buff *skb, struct net_device *dev,
+		   struct packet_type *pt, struct net_device *orig_dev)
+{
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (unlikely(!net_eq(dev_net(dev), &init_net)))
+		goto drop;
+
+	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
+		      skb->len != CAN_MTU ||
+		      cfd->len > CAN_MAX_DLEN,
+		      "PF_CAN: dropped non conform CAN skbuf: "
+		      "dev type %d, len %d, datalen %d\n",
+		      dev->type, skb->len, cfd->len))
+		goto drop;
+
+	can_receive(skb, dev);
+	return NET_RX_SUCCESS;
+
+drop:
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}
+
+static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
+		   struct packet_type *pt, struct net_device *orig_dev)
+{
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (unlikely(!net_eq(dev_net(dev), &init_net)))
+		goto drop;
+
+	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
+		      skb->len != CANFD_MTU ||
+		      cfd->len > CANFD_MAX_DLEN,
+		      "PF_CAN: dropped non conform CAN FD skbuf: "
+		      "dev type %d, len %d, datalen %d\n",
+		      dev->type, skb->len, cfd->len))
+		goto drop;
+
+	can_receive(skb, dev);
 	return NET_RX_SUCCESS;
 
 drop:
@@ -807,10 +857,14 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
 
 static struct packet_type can_packet __read_mostly = {
 	.type = cpu_to_be16(ETH_P_CAN),
-	.dev  = NULL,
 	.func = can_rcv,
 };
 
+static struct packet_type canfd_packet __read_mostly = {
+	.type = cpu_to_be16(ETH_P_CANFD),
+	.func = canfd_rcv,
+};
+
 static const struct net_proto_family can_family_ops = {
 	.family = PF_CAN,
 	.create = can_create,
@@ -824,6 +878,12 @@ static struct notifier_block can_netdev_notifier __read_mostly = {
 
 static __init int can_init(void)
 {
+	/* check for correct padding to be able to use the structs similarly */
+	BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
+		     offsetof(struct canfd_frame, len) ||
+		     offsetof(struct can_frame, data) !=
+		     offsetof(struct canfd_frame, data));
+
 	printk(banner);
 
 	memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
@@ -846,6 +906,7 @@ static __init int can_init(void)
 	sock_register(&can_family_ops);
 	register_netdevice_notifier(&can_netdev_notifier);
 	dev_add_pack(&can_packet);
+	dev_add_pack(&canfd_packet);
 
 	return 0;
 }
@@ -860,6 +921,7 @@ static __exit void can_exit(void)
 	can_remove_proc();
 
 	/* protocol unregister */
+	dev_remove_pack(&canfd_packet);
 	dev_remove_pack(&can_packet);
 	unregister_netdevice_notifier(&can_netdev_notifier);
 	sock_unregister(PF_CAN);
diff --git a/net/can/raw.c b/net/can/raw.c
index cde1b4a..44638c5 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -82,6 +82,7 @@ struct raw_sock {
 	struct notifier_block notifier;
 	int loopback;
 	int recv_own_msgs;
+	int fd_frames;
 	int count;                 /* number of active filters */
 	struct can_filter dfilter; /* default/single filter */
 	struct can_filter *filter; /* pointer to filter(s) */
@@ -119,6 +120,14 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (!ro->recv_own_msgs && oskb->sk == sk)
 		return;
 
+	/* do not pass frames with DLC > 8 to a legacy socket */
+	if (!ro->fd_frames) {
+		struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
+
+		if (unlikely(cfd->len > CAN_MAX_DLEN))
+			return;
+	}
+
 	/* clone the given skb to be able to enqueue it into the rcv queue */
 	skb = skb_clone(oskb, GFP_ATOMIC);
 	if (!skb)
@@ -291,6 +300,7 @@ static int raw_init(struct sock *sk)
 	/* set default loopback behaviour */
 	ro->loopback         = 1;
 	ro->recv_own_msgs    = 0;
+	ro->fd_frames        = 0;
 
 	/* set notifier */
 	ro->notifier.notifier_call = raw_notifier;
@@ -569,6 +579,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case CAN_RAW_FD_FRAMES:
+		if (optlen != sizeof(ro->fd_frames))
+			return -EINVAL;
+
+		if (copy_from_user(&ro->fd_frames, optval, optlen))
+			return -EFAULT;
+
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}
@@ -627,6 +646,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 		val = &ro->recv_own_msgs;
 		break;
 
+	case CAN_RAW_FD_FRAMES:
+		if (len > sizeof(int))
+			len = sizeof(int);
+		val = &ro->fd_frames;
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}
@@ -662,8 +687,13 @@ static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
 	} else
 		ifindex = ro->ifindex;
 
-	if (size != sizeof(struct can_frame))
-		return -EINVAL;
+	if (ro->fd_frames) {
+		if (unlikely(size != CANFD_MTU && size != CAN_MTU))
+			return -EINVAL;
+	} else {
+		if (unlikely(size != CAN_MTU))
+			return -EINVAL;
+	}
 
 	dev = dev_get_by_index(&init_net, ifindex);
 	if (!dev)
@@ -708,7 +738,9 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
 		       struct msghdr *msg, size_t size, int flags)
 {
 	struct sock *sk = sock->sk;
+	struct raw_sock *ro = raw_sk(sk);
 	struct sk_buff *skb;
+	int rxmtu;
 	int err = 0;
 	int noblock;
 
@@ -719,10 +751,20 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
 	if (!skb)
 		return err;
 
-	if (size < skb->len)
+	/*
+	 * when serving a legacy socket the DLC <= 8 is already checked inside
+	 * raw_rcv(). Now check if we need to pass a canfd_frame to a legacy
+	 * socket and cut the possible CANFD_MTU/CAN_MTU length to CAN_MTU
+	 */
+	if (!ro->fd_frames)
+		rxmtu = CAN_MTU;
+	else
+		rxmtu = skb->len;
+
+	if (size < rxmtu)
 		msg->msg_flags |= MSG_TRUNC;
 	else
-		size = skb->len;
+		size = rxmtu;
 
 	err = memcpy_toiovec(msg->msg_iov, skb->data, size);
 	if (err < 0) {





^ permalink raw reply related	[flat|nested] 5+ messages in thread