net/nsh/nsh.c

   1 /*
   2  * Network Service Header
   3  *
   4  * Copyright (c) 2017 Red Hat, Inc. -- Jiri Benc <jbenc@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/skbuff.h>
  14 #include <net/nsh.h>
  15 #include <net/tun_proto.h>
  16
  17 int nsh_push(struct sk_buff *skb, const struct nshhdr *pushed_nh)
  18 {
  19         struct nshhdr *nh;
  20         size_t length = nsh_hdr_len(pushed_nh);
  21         u8 next_proto;
  22
  23         if (skb->mac_len) {
  24                 next_proto = TUN_P_ETHERNET;
  25         } else {
  26                 next_proto = tun_p_from_eth_p(skb->protocol);
  27                 if (!next_proto)
  28                         return -EAFNOSUPPORT;
  29         }
  30
  31         /* Add the NSH header */
  32         if (skb_cow_head(skb, length) < 0)
  33                 return -ENOMEM;
  34
  35         skb_push(skb, length);
  36         nh = (struct nshhdr *)(skb->data);
  37         memcpy(nh, pushed_nh, length);
  38         nh->np = next_proto;
  39         skb_postpush_rcsum(skb, nh, length);
  40
  41         skb->protocol = htons(ETH_P_NSH);
  42         skb_reset_mac_header(skb);
  43         skb_reset_network_header(skb);
  44         skb_reset_mac_len(skb);
  45
  46         return 0;
  47 }
  48 EXPORT_SYMBOL_GPL(nsh_push);
  49
  50 int nsh_pop(struct sk_buff *skb)
  51 {
  52         struct nshhdr *nh;
  53         size_t length;
  54         __be16 inner_proto;
  55
  56         if (!pskb_may_pull(skb, NSH_BASE_HDR_LEN))
  57                 return -ENOMEM;
  58         nh = (struct nshhdr *)(skb->data);
  59         length = nsh_hdr_len(nh);
  60         inner_proto = tun_p_to_eth_p(nh->np);
  61         if (!pskb_may_pull(skb, length))
  62                 return -ENOMEM;
  63
  64         if (!inner_proto)
  65                 return -EAFNOSUPPORT;
  66
  67         skb_pull_rcsum(skb, length);
  68         skb_reset_mac_header(skb);
  69         skb_reset_network_header(skb);
  70         skb_reset_mac_len(skb);
  71         skb->protocol = inner_proto;
  72
  73         return 0;
  74 }
  75 EXPORT_SYMBOL_GPL(nsh_pop);
  76
  77 static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
  78                                        netdev_features_t features)
  79 {
  80         struct sk_buff *segs = ERR_PTR(-EINVAL);
  81         unsigned int nsh_len, mac_len;
  82         __be16 proto;
  83         int nhoff;
  84
  85         skb_reset_network_header(skb);
  86
  87         nhoff = skb->network_header - skb->mac_header;
  88         mac_len = skb->mac_len;
  89
  90         if (unlikely(!pskb_may_pull(skb, NSH_BASE_HDR_LEN)))
  91                 goto out;
  92         nsh_len = nsh_hdr_len(nsh_hdr(skb));
  93         if (unlikely(!pskb_may_pull(skb, nsh_len)))
  94                 goto out;
  95
  96         proto = tun_p_to_eth_p(nsh_hdr(skb)->np);
  97         if (!proto)
  98                 goto out;
  99
 100         __skb_pull(skb, nsh_len);
 101
 102         skb_reset_mac_header(skb);
 103         skb_reset_mac_len(skb);
 104         skb->protocol = proto;
 105
 106         features &= NETIF_F_SG;
 107         segs = skb_mac_gso_segment(skb, features);
 108         if (IS_ERR_OR_NULL(segs)) {
 109                 skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len,
 110                                      skb->network_header - nhoff,
 111                                      mac_len);
 112                 goto out;
 113         }
 114
 115         for (skb = segs; skb; skb = skb->next) {
 116                 skb->protocol = htons(ETH_P_NSH);
 117                 __skb_push(skb, nsh_len);
 118                 skb_set_mac_header(skb, -nhoff);
 119                 skb->network_header = skb->mac_header + mac_len;
 120                 skb->mac_len = mac_len;
 121         }
 122
 123 out:
 124         return segs;
 125 }
 126
 127 static struct packet_offload nsh_packet_offload __read_mostly = {
 128         .type = htons(ETH_P_NSH),
 129         .priority = 15,
 130         .callbacks = {
 131                 .gso_segment = nsh_gso_segment,
 132         },
 133 };
 134
 135 static int __init nsh_init_module(void)
 136 {
 137         dev_add_offload(&nsh_packet_offload);
 138         return 0;
 139 }
 140
 141 static void __exit nsh_cleanup_module(void)
 142 {
 143         dev_remove_offload(&nsh_packet_offload);
 144 }
 145
 146 module_init(nsh_init_module);
 147 module_exit(nsh_cleanup_module);
 148
 149 MODULE_AUTHOR("Jiri Benc <jbenc@redhat.com>");
 150 MODULE_DESCRIPTION("NSH protocol");
 151 MODULE_LICENSE("GPL v2");