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 static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
  18                                        netdev_features_t features)
  19 {
  20         struct sk_buff *segs = ERR_PTR(-EINVAL);
  21         unsigned int nsh_len, mac_len;
  22         __be16 proto;
  23         int nhoff;
  24
  25         skb_reset_network_header(skb);
  26
  27         nhoff = skb->network_header - skb->mac_header;
  28         mac_len = skb->mac_len;
  29
  30         if (unlikely(!pskb_may_pull(skb, NSH_BASE_HDR_LEN)))
  31                 goto out;
  32         nsh_len = nsh_hdr_len(nsh_hdr(skb));
  33         if (nsh_len < NSH_BASE_HDR_LEN)
  34                 goto out;
  35         if (unlikely(!pskb_may_pull(skb, nsh_len)))
  36                 goto out;
  37
  38         proto = tun_p_to_eth_p(nsh_hdr(skb)->np);
  39         if (!proto)
  40                 goto out;
  41
  42         __skb_pull(skb, nsh_len);
  43
  44         skb_reset_mac_header(skb);
  45         skb->mac_len = proto == htons(ETH_P_TEB) ? ETH_HLEN : 0;
  46         skb->protocol = proto;
  47
  48         features &= NETIF_F_SG;
  49         segs = skb_mac_gso_segment(skb, features);
  50         if (IS_ERR_OR_NULL(segs)) {
  51                 skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len,
  52                                      skb->network_header - nhoff,
  53                                      mac_len);
  54                 goto out;
  55         }
  56
  57         for (skb = segs; skb; skb = skb->next) {
  58                 skb->protocol = htons(ETH_P_NSH);
  59                 __skb_push(skb, nsh_len);
  60                 skb_set_mac_header(skb, -nhoff);
  61                 skb->network_header = skb->mac_header + mac_len;
  62                 skb->mac_len = mac_len;
  63         }
  64
  65 out:
  66         return segs;
  67 }
  68
  69 static struct packet_offload nsh_packet_offload __read_mostly = {
  70         .type = htons(ETH_P_NSH),
  71         .priority = 15,
  72         .callbacks = {
  73                 .gso_segment = nsh_gso_segment,
  74         },
  75 };
  76
  77 static int __init nsh_init_module(void)
  78 {
  79         dev_add_offload(&nsh_packet_offload);
  80         return 0;
  81 }
  82
  83 static void __exit nsh_cleanup_module(void)
  84 {
  85         dev_remove_offload(&nsh_packet_offload);
  86 }
  87
  88 module_init(nsh_init_module);
  89 module_exit(nsh_cleanup_module);
  90
  91 MODULE_AUTHOR("Jiri Benc <jbenc@redhat.com>");
  92 MODULE_DESCRIPTION("NSH protocol");
  93 MODULE_LICENSE("GPL v2");