5 files changed, 176 insertions, 96 deletions

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 0ce2ad0696d..821022a7214 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);
 
@@ -334,8 +355,8 @@ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
  *  relevant bits for the filter.
  *
  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
- *  filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames
- *  there is a special filterlist and a special rx path filter handling.
+ *  filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
+ *  frames there is a special filterlist and a special rx path filter handling.
  *
  * Return:
  *  Pointer to optimal filterlist for the given can_id/mask pair.
@@ -347,7 +368,7 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
 {
 	canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
 
-	/* filter for error frames in extra filterlist */
+	/* filter for error message frames in extra filterlist */
 	if (*mask & CAN_ERR_FLAG) {
 		/* clear CAN_ERR_FLAG in filter entry */
 		*mask &= CAN_ERR_MASK;
@@ -408,7 +429,7 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
  *          <received_can_id> & mask == can_id & mask
  *
  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
- *  filter for error frames (CAN_ERR_FLAG bit set in mask).
+ *  filter for error message frames (CAN_ERR_FLAG bit set in mask).
  *
  *  The provided pointer to the sk_buff is guaranteed to be valid as long as
  *  the callback function is running. The callback function must *not* free
@@ -578,7 +599,7 @@ static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
 		return 0;
 
 	if (can_id & CAN_ERR_FLAG) {
-		/* check for error frame entries only */
+		/* check for error message frame entries only */
 		hlist_for_each_entry_rcu(r, n, &d->rx[RX_ERR], list) {
 			if (can_id & r->mask) {
 				deliver(skb, r);
@@ -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/af_can.h b/net/can/af_can.h
index fd882dbadad..1dccb4c3389 100644
--- a/net/can/af_can.h
+++ b/net/can/af_can.h
@@ -104,6 +104,9 @@ struct s_pstats {
 	unsigned long rcv_entries_max;
 };
 
+/* receive filters subscribed for 'all' CAN devices */
+extern struct dev_rcv_lists can_rx_alldev_list;
+
 /* function prototypes for the CAN networklayer procfs (proc.c) */
 extern void can_init_proc(void);
 extern void can_remove_proc(void);
diff --git a/net/can/gw.c b/net/can/gw.c
index b41acf25668..b54d5e695b0 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -444,11 +444,14 @@ static int cgw_notifier(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
-static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
+static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
+		       u32 pid, u32 seq, int flags)
 {
 	struct cgw_frame_mod mb;
 	struct rtcanmsg *rtcan;
-	struct nlmsghdr *nlh = nlmsg_put(skb, 0, 0, 0, sizeof(*rtcan), 0);
+	struct nlmsghdr *nlh;
+
+	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
 	if (!nlh)
 		return -EMSGSIZE;
 
@@ -462,15 +465,11 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 	if (gwj->handled_frames) {
 		if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(u32));
 	}
 
 	if (gwj->dropped_frames) {
 		if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(u32));
 	}
 
 	/* check non default settings of attributes */
@@ -480,8 +479,6 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 		mb.modtype = gwj->mod.modtype.and;
 		if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(mb));
 	}
 
 	if (gwj->mod.modtype.or) {
@@ -489,8 +486,6 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 		mb.modtype = gwj->mod.modtype.or;
 		if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(mb));
 	}
 
 	if (gwj->mod.modtype.xor) {
@@ -498,8 +493,6 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 		mb.modtype = gwj->mod.modtype.xor;
 		if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(mb));
 	}
 
 	if (gwj->mod.modtype.set) {
@@ -507,26 +500,18 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 		mb.modtype = gwj->mod.modtype.set;
 		if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(mb));
 	}
 
 	if (gwj->mod.csumfunc.crc8) {
 		if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
 			    &gwj->mod.csum.crc8) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + \
-				NLA_ALIGN(CGW_CS_CRC8_LEN);
 	}
 
 	if (gwj->mod.csumfunc.xor) {
 		if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
 			    &gwj->mod.csum.xor) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + \
-				NLA_ALIGN(CGW_CS_XOR_LEN);
 	}
 
 	if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
@@ -535,23 +520,16 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
 			if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
 				    &gwj->ccgw.filter) < 0)
 				goto cancel;
-			else
-				nlh->nlmsg_len += NLA_HDRLEN +
-					NLA_ALIGN(sizeof(struct can_filter));
 		}
 
 		if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(u32));
 
 		if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
 			goto cancel;
-		else
-			nlh->nlmsg_len += NLA_HDRLEN + NLA_ALIGN(sizeof(u32));
 	}
 
-	return skb->len;
+	return nlmsg_end(skb, nlh);
 
 cancel:
 	nlmsg_cancel(skb, nlh);
@@ -571,7 +549,8 @@ static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
 		if (idx < s_idx)
 			goto cont;
 
-		if (cgw_put_job(skb, gwj) < 0)
+		if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).pid,
+		    cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
 			break;
 cont:
 		idx++;
@@ -583,6 +562,18 @@ cont:
 	return skb->len;
 }
 
+static const struct nla_policy cgw_policy[CGW_MAX+1] = {
+	[CGW_MOD_AND]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_OR]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_XOR]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_SET]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_CS_XOR]	= { .len = sizeof(struct cgw_csum_xor) },
+	[CGW_CS_CRC8]	= { .len = sizeof(struct cgw_csum_crc8) },
+	[CGW_SRC_IF]	= { .type = NLA_U32 },
+	[CGW_DST_IF]	= { .type = NLA_U32 },
+	[CGW_FILTER]	= { .len = sizeof(struct can_filter) },
+};
+
 /* check for common and gwtype specific attributes */
 static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			  u8 gwtype, void *gwtypeattr)
@@ -595,14 +586,14 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 	/* initialize modification & checksum data space */
 	memset(mod, 0, sizeof(*mod));
 
-	err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX, NULL);
+	err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
+			  cgw_policy);
 	if (err < 0)
 		return err;
 
 	/* check for AND/OR/XOR/SET modifications */
 
-	if (tb[CGW_MOD_AND] &&
-	    nla_len(tb[CGW_MOD_AND]) == CGW_MODATTR_LEN) {
+	if (tb[CGW_MOD_AND]) {
 		nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
 
 		canframecpy(&mod->modframe.and, &mb.cf);
@@ -618,8 +609,7 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			mod->modfunc[modidx++] = mod_and_data;
 	}
 
-	if (tb[CGW_MOD_OR] &&
-	    nla_len(tb[CGW_MOD_OR]) == CGW_MODATTR_LEN) {
+	if (tb[CGW_MOD_OR]) {
 		nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
 
 		canframecpy(&mod->modframe.or, &mb.cf);
@@ -635,8 +625,7 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			mod->modfunc[modidx++] = mod_or_data;
 	}
 
-	if (tb[CGW_MOD_XOR] &&
-	    nla_len(tb[CGW_MOD_XOR]) == CGW_MODATTR_LEN) {
+	if (tb[CGW_MOD_XOR]) {
 		nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
 
 		canframecpy(&mod->modframe.xor, &mb.cf);
@@ -652,8 +641,7 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			mod->modfunc[modidx++] = mod_xor_data;
 	}
 
-	if (tb[CGW_MOD_SET] &&
-	    nla_len(tb[CGW_MOD_SET]) == CGW_MODATTR_LEN) {
+	if (tb[CGW_MOD_SET]) {
 		nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
 
 		canframecpy(&mod->modframe.set, &mb.cf);
@@ -672,11 +660,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 	/* check for checksum operations after CAN frame modifications */
 	if (modidx) {
 
-		if (tb[CGW_CS_CRC8] &&
-		    nla_len(tb[CGW_CS_CRC8]) == CGW_CS_CRC8_LEN) {
-
-			struct cgw_csum_crc8 *c = (struct cgw_csum_crc8 *)\
-				nla_data(tb[CGW_CS_CRC8]);
+		if (tb[CGW_CS_CRC8]) {
+			struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
 
 			err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
 						 c->result_idx);
@@ -699,11 +684,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 				mod->csumfunc.crc8 = cgw_csum_crc8_neg;
 		}
 
-		if (tb[CGW_CS_XOR] &&
-		    nla_len(tb[CGW_CS_XOR]) == CGW_CS_XOR_LEN) {
-
-			struct cgw_csum_xor *c = (struct cgw_csum_xor *)\
-				nla_data(tb[CGW_CS_XOR]);
+		if (tb[CGW_CS_XOR]) {
+			struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
 
 			err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
 						 c->result_idx);
@@ -735,8 +717,7 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 		memset(ccgw, 0, sizeof(*ccgw));
 
 		/* check for can_filter in attributes */
-		if (tb[CGW_FILTER] &&
-		    nla_len(tb[CGW_FILTER]) == sizeof(struct can_filter))
+		if (tb[CGW_FILTER])
 			nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
 				   sizeof(struct can_filter));
 
@@ -746,13 +727,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 		if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
 			return err;
 
-		if (nla_len(tb[CGW_SRC_IF]) == sizeof(u32))
-			nla_memcpy(&ccgw->src_idx, tb[CGW_SRC_IF],
-				   sizeof(u32));
-
-		if (nla_len(tb[CGW_DST_IF]) == sizeof(u32))
-			nla_memcpy(&ccgw->dst_idx, tb[CGW_DST_IF],
-				   sizeof(u32));
+		ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
+		ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
 
 		/* both indices set to 0 for flushing all routing entries */
 		if (!ccgw->src_idx && !ccgw->dst_idx)
diff --git a/net/can/proc.c b/net/can/proc.c
index ba873c36d2f..3b6dd318049 100644
--- a/net/can/proc.c
+++ b/net/can/proc.c
@@ -83,9 +83,6 @@ static const char rx_list_name[][8] = {
 	[RX_EFF] = "rx_eff",
 };
 
-/* receive filters subscribed for 'all' CAN devices */
-extern struct dev_rcv_lists can_rx_alldev_list;
-
 /*
  * af_can statistics stuff
  */
diff --git a/net/can/raw.c b/net/can/raw.c
index 46cca3a91d1..3e9c89356a9 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)
@@ -705,7 +735,9 @@ 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;
 
@@ -716,10 +748,20 @@ 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) {