1 /* 2 * net/dsa/tag_trailer.c - Trailer tag format handling 3 * Copyright (c) 2008-2009 Marvell Semiconductor 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 */ 10 11 #include <linux/etherdevice.h> 12 #include <linux/list.h> 13 #include <linux/slab.h> 14 #include <net/dsa.h> 15 #include "dsa_priv.h" 16 17 static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev) 18 { 19 struct dsa_slave_priv *p = netdev_priv(dev); 20 struct sk_buff *nskb; 21 int padlen; 22 u8 *trailer; 23 24 /* 25 * We have to make sure that the trailer ends up as the very 26 * last 4 bytes of the packet. This means that we have to pad 27 * the packet to the minimum ethernet frame size, if necessary, 28 * before adding the trailer. 29 */ 30 padlen = 0; 31 if (skb->len < 60) 32 padlen = 60 - skb->len; 33 34 nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC); 35 if (nskb == NULL) { 36 kfree_skb(skb); 37 return NULL; 38 } 39 skb_reserve(nskb, NET_IP_ALIGN); 40 41 skb_reset_mac_header(nskb); 42 skb_set_network_header(nskb, skb_network_header(skb) - skb->head); 43 skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head); 44 skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len)); 45 kfree_skb(skb); 46 47 if (padlen) { 48 u8 *pad = skb_put(nskb, padlen); 49 memset(pad, 0, padlen); 50 } 51 52 trailer = skb_put(nskb, 4); 53 trailer[0] = 0x80; 54 trailer[1] = 1 << p->dp->index; 55 trailer[2] = 0x10; 56 trailer[3] = 0x00; 57 58 return nskb; 59 } 60 61 static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev, 62 struct packet_type *pt, 63 struct net_device *orig_dev) 64 { 65 struct dsa_switch_tree *dst = dev->dsa_ptr; 66 struct dsa_switch *ds; 67 u8 *trailer; 68 int source_port; 69 70 ds = dst->cpu_switch; 71 72 if (skb_linearize(skb)) 73 goto out_drop; 74 75 trailer = skb_tail_pointer(skb) - 4; 76 if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 || 77 (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00) 78 goto out_drop; 79 80 source_port = trailer[1] & 7; 81 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev) 82 goto out_drop; 83 84 pskb_trim_rcsum(skb, skb->len - 4); 85 86 skb->dev = ds->ports[source_port].netdev; 87 88 return skb; 89 90 out_drop: 91 return NULL; 92 } 93 94 const struct dsa_device_ops trailer_netdev_ops = { 95 .xmit = trailer_xmit, 96 .rcv = trailer_rcv, 97 }; 98