net/mpls/mpls_gso.c

   1 /*
   2  *      MPLS GSO Support
   3  *
   4  *      Authors: Simon Horman (horms@verge.net.au)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  *      Based on: GSO portions of net/ipv4/gre.c
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/err.h>
  17 #include <linux/module.h>
  18 #include <linux/netdev_features.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/skbuff.h>
  21
  22 static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
  23                                        netdev_features_t features)
  24 {
  25         struct sk_buff *segs = ERR_PTR(-EINVAL);
  26         netdev_features_t mpls_features;
  27         __be16 mpls_protocol;
  28
  29         /* Setup inner SKB. */
  30         mpls_protocol = skb->protocol;
  31         skb->protocol = skb->inner_protocol;
  32
  33         /* Push back the mac header that skb_mac_gso_segment() has pulled.
  34          * It will be re-pulled by the call to skb_mac_gso_segment() below
  35          */
  36         __skb_push(skb, skb->mac_len);
  37
  38         /* Segment inner packet. */
  39         mpls_features = skb->dev->mpls_features & features;
  40         segs = skb_mac_gso_segment(skb, mpls_features);
  41
  42
  43         /* Restore outer protocol. */
  44         skb->protocol = mpls_protocol;
  45
  46         /* Re-pull the mac header that the call to skb_mac_gso_segment()
  47          * above pulled.  It will be re-pushed after returning
  48          * skb_mac_gso_segment(), an indirect caller of this function.
  49          */
  50         __skb_pull(skb, skb->data - skb_mac_header(skb));
  51
  52         return segs;
  53 }
  54
  55 static struct packet_offload mpls_mc_offload __read_mostly = {
  56         .type = cpu_to_be16(ETH_P_MPLS_MC),
  57         .priority = 15,
  58         .callbacks = {
  59                 .gso_segment    =       mpls_gso_segment,
  60         },
  61 };
  62
  63 static struct packet_offload mpls_uc_offload __read_mostly = {
  64         .type = cpu_to_be16(ETH_P_MPLS_UC),
  65         .priority = 15,
  66         .callbacks = {
  67                 .gso_segment    =       mpls_gso_segment,
  68         },
  69 };
  70
  71 static int __init mpls_gso_init(void)
  72 {
  73         pr_info("MPLS GSO support\n");
  74
  75         dev_add_offload(&mpls_uc_offload);
  76         dev_add_offload(&mpls_mc_offload);
  77
  78         return 0;
  79 }
  80
  81 static void __exit mpls_gso_exit(void)
  82 {
  83         dev_remove_offload(&mpls_uc_offload);
  84         dev_remove_offload(&mpls_mc_offload);
  85 }
  86
  87 module_init(mpls_gso_init);
  88 module_exit(mpls_gso_exit);
  89
  90 MODULE_DESCRIPTION("MPLS GSO support");
  91 MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
  92 MODULE_LICENSE("GPL");