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 "dsa_priv.h" 15 16 static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev) 17 { 18 struct dsa_slave_priv *p = netdev_priv(dev); 19 struct sk_buff *nskb; 20 int padlen; 21 u8 *trailer; 22 23 /* 24 * We have to make sure that the trailer ends up as the very 25 * last 4 bytes of the packet. This means that we have to pad 26 * the packet to the minimum ethernet frame size, if necessary, 27 * before adding the trailer. 28 */ 29 padlen = 0; 30 if (skb->len < 60) 31 padlen = 60 - skb->len; 32 33 nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC); 34 if (nskb == NULL) { 35 kfree_skb(skb); 36 return NULL; 37 } 38 skb_reserve(nskb, NET_IP_ALIGN); 39 40 skb_reset_mac_header(nskb); 41 skb_set_network_header(nskb, skb_network_header(skb) - skb->head); 42 skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head); 43 skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len)); 44 kfree_skb(skb); 45 46 if (padlen) { 47 u8 *pad = skb_put(nskb, padlen); 48 memset(pad, 0, padlen); 49 } 50 51 trailer = skb_put(nskb, 4); 52 trailer[0] = 0x80; 53 trailer[1] = 1 << p->dp->index; 54 trailer[2] = 0x10; 55 trailer[3] = 0x00; 56 57 return nskb; 58 } 59 60 static int trailer_rcv(struct sk_buff *skb, struct net_device *dev, 61 struct packet_type *pt, struct net_device *orig_dev) 62 { 63 struct dsa_switch_tree *dst = dev->dsa_ptr; 64 struct dsa_switch *ds; 65 u8 *trailer; 66 int source_port; 67 68 if (unlikely(dst == NULL)) 69 goto out_drop; 70 ds = dst->cpu_switch; 71 72 skb = skb_unshare(skb, GFP_ATOMIC); 73 if (skb == NULL) 74 goto out; 75 76 if (skb_linearize(skb)) 77 goto out_drop; 78 79 trailer = skb_tail_pointer(skb) - 4; 80 if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 || 81 (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00) 82 goto out_drop; 83 84 source_port = trailer[1] & 7; 85 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev) 86 goto out_drop; 87 88 pskb_trim_rcsum(skb, skb->len - 4); 89 90 skb->dev = ds->ports[source_port].netdev; 91 skb_push(skb, ETH_HLEN); 92 skb->pkt_type = PACKET_HOST; 93 skb->protocol = eth_type_trans(skb, skb->dev); 94 95 skb->dev->stats.rx_packets++; 96 skb->dev->stats.rx_bytes += skb->len; 97 98 netif_receive_skb(skb); 99 100 return 0; 101 102 out_drop: 103 kfree_skb(skb); 104 out: 105 return 0; 106 } 107 108 const struct dsa_device_ops trailer_netdev_ops = { 109 .xmit = trailer_xmit, 110 .rcv = trailer_rcv, 111 }; 112