[linux-2.6-block.git] / net / dsa / tag_trailer.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * net/dsa/tag_trailer.c - Trailer tag format handling
 * Copyright (c) 2008-2009 Marvell Semiconductor
 */

#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>

#include "dsa_priv.h"

static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct dsa_port *dp = dsa_slave_to_port(dev);
	struct sk_buff *nskb;
	int padlen;
	u8 *trailer;

	/*
	 * We have to make sure that the trailer ends up as the very
	 * last 4 bytes of the packet.  This means that we have to pad
	 * the packet to the minimum ethernet frame size, if necessary,
	 * before adding the trailer.
	 */
	padlen = 0;
	if (skb->len < 60)
		padlen = 60 - skb->len;

	nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
	if (!nskb)
		return NULL;
	skb_reserve(nskb, NET_IP_ALIGN);

	skb_reset_mac_header(nskb);
	skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
	skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
	skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
	consume_skb(skb);

	if (padlen) {
		skb_put_zero(nskb, padlen);
	}

	trailer = skb_put(nskb, 4);
	trailer[0] = 0x80;
	trailer[1] = 1 << dp->index;
	trailer[2] = 0x10;
	trailer[3] = 0x00;

	return nskb;
}

static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
				   struct packet_type *pt)
{
	u8 *trailer;
	int source_port;

	if (skb_linearize(skb))
		return NULL;

	trailer = skb_tail_pointer(skb) - 4;
	if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
	    (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
		return NULL;

	source_port = trailer[1] & 7;

	skb->dev = dsa_master_find_slave(dev, 0, source_port);
	if (!skb->dev)
		return NULL;

	if (pskb_trim_rcsum(skb, skb->len - 4))
		return NULL;

	return skb;
}

const struct dsa_device_ops trailer_netdev_ops = {
	.name	= "trailer",
	.xmit	= trailer_xmit,
	.rcv	= trailer_rcv,
	.overhead = 4,
};

MODULE_LICENSE("GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER);
Commit	Line	Data
dfedd3b6	1	// SPDX-License-Identifier: GPL-2.0+
396138f0 LB	2	/*
396138f0 LB	3	* net/dsa/tag_trailer.c - Trailer tag format handling
e84665c9	4	* Copyright (c) 2008-2009 Marvell Semiconductor
396138f0 LB	5	*/
	6
	7	#include <linux/etherdevice.h>
	8	#include <linux/list.h>
5a0e3ad6	9	#include <linux/slab.h>
ea5dd34b	10
396138f0 LB	11	#include "dsa_priv.h"
396138f0 LB	12
4ed70ce9	13	static struct sk_buff trailer_xmit(struct sk_buff skb, struct net_device *dev)
396138f0	14	{
d945097b	15	struct dsa_port *dp = dsa_slave_to_port(dev);
396138f0 LB	16	struct sk_buff *nskb;
	17	int padlen;
	18	u8 *trailer;
	19
396138f0 LB	20	/*
	21	* We have to make sure that the trailer ends up as the very
	22	* last 4 bytes of the packet. This means that we have to pad
	23	* the packet to the minimum ethernet frame size, if necessary,
	24	* before adding the trailer.
	25	*/
	26	padlen = 0;
	27	if (skb->len < 60)
	28	padlen = 60 - skb->len;
	29
	30	nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
fe47d563	31	if (!nskb)
4ed70ce9	32	return NULL;
396138f0 LB	33	skb_reserve(nskb, NET_IP_ALIGN);
	34
	35	skb_reset_mac_header(nskb);
	36	skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
	37	skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
	38	skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
2b33bc8a	39	consume_skb(skb);
396138f0 LB	40
396138f0 LB	41	if (padlen) {
b952f4df	42	skb_put_zero(nskb, padlen);
396138f0 LB	43	}
	44
	45	trailer = skb_put(nskb, 4);
	46	trailer[0] = 0x80;
d945097b	47	trailer[1] = 1 << dp->index;
396138f0 LB	48	trailer[2] = 0x10;
	49	trailer[3] = 0x00;
	50
4ed70ce9	51	return nskb;
396138f0 LB	52	}
396138f0 LB	53
a86d8bec	54	static struct sk_buff trailer_rcv(struct sk_buff skb, struct net_device *dev,
89e49506	55	struct packet_type *pt)
396138f0	56	{
396138f0 LB	57	u8 *trailer;
	58	int source_port;
	59
396138f0	60	if (skb_linearize(skb))
54709795	61	return NULL;
396138f0 LB	62
	63	trailer = skb_tail_pointer(skb) - 4;
	64	if (trailer[0] != 0x80 \|\| (trailer[1] & 0xf8) != 0x00 \|\|
fbd03513	65	(trailer[2] & 0xef) != 0x00 \|\| trailer[3] != 0x00)
54709795	66	return NULL;
396138f0 LB	67
396138f0 LB	68	source_port = trailer[1] & 7;
3775b1b7	69
2231c43b	70	skb->dev = dsa_master_find_slave(dev, 0, source_port);
3775b1b7	71	if (!skb->dev)
54709795	72	return NULL;
396138f0	73
349b71d6 ZJ	74	if (pskb_trim_rcsum(skb, skb->len - 4))
349b71d6 ZJ	75	return NULL;
396138f0	76
a86d8bec	77	return skb;
396138f0 LB	78	}
396138f0 LB	79
3e8a72d1	80	const struct dsa_device_ops trailer_netdev_ops = {
875138f8	81	.name = "trailer",
3e8a72d1 FF	82	.xmit = trailer_xmit,
3e8a72d1 FF	83	.rcv = trailer_rcv,
a5dd3087	84	.overhead = 4,
396138f0	85	};
0b42f033	86
f18bba50	87	MODULE_LICENSE("GPL");
0b42f033	88	MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER);