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         if (unlikely(skb_shinfo(skb)->gso_type &
  30                                 ~(SKB_GSO_TCPV4 |
  31                                   SKB_GSO_TCPV6 |
  32                                   SKB_GSO_UDP |
  33                                   SKB_GSO_DODGY |
  34                                   SKB_GSO_TCP_ECN)))
  35                 goto out;
  36
  37         /* Setup inner SKB. */
  38         mpls_protocol = skb->protocol;
  39         skb->protocol = skb->inner_protocol;
  40
  41         /* Push back the mac header that skb_mac_gso_segment() has pulled.
  42          * It will be re-pulled by the call to skb_mac_gso_segment() below
  43          */
  44         __skb_push(skb, skb->mac_len);
  45
  46         /* Segment inner packet. */
  47         mpls_features = skb->dev->mpls_features & features;
  48         segs = skb_mac_gso_segment(skb, mpls_features);
  49
  50
  51         /* Restore outer protocol. */
  52         skb->protocol = mpls_protocol;
  53
  54         /* Re-pull the mac header that the call to skb_mac_gso_segment()
  55          * above pulled.  It will be re-pushed after returning
  56          * skb_mac_gso_segment(), an indirect caller of this function.
  57          */
  58         __skb_pull(skb, skb->data - skb_mac_header(skb));
  59 out:
  60         return segs;
  61 }
  62
  63 static struct packet_offload mpls_mc_offload __read_mostly = {
  64         .type = cpu_to_be16(ETH_P_MPLS_MC),
  65         .callbacks = {
  66                 .gso_segment    =       mpls_gso_segment,
  67         },
  68 };
  69
  70 static struct packet_offload mpls_uc_offload __read_mostly = {
  71         .type = cpu_to_be16(ETH_P_MPLS_UC),
  72         .callbacks = {
  73                 .gso_segment    =       mpls_gso_segment,
  74         },
  75 };
  76
  77 static int __init mpls_gso_init(void)
  78 {
  79         pr_info("MPLS GSO support\n");
  80
  81         dev_add_offload(&mpls_uc_offload);
  82         dev_add_offload(&mpls_mc_offload);
  83
  84         return 0;
  85 }
  86
  87 static void __exit mpls_gso_exit(void)
  88 {
  89         dev_remove_offload(&mpls_uc_offload);
  90         dev_remove_offload(&mpls_mc_offload);
  91 }
  92
  93 module_init(mpls_gso_init);
  94 module_exit(mpls_gso_exit);
  95
  96 MODULE_DESCRIPTION("MPLS GSO support");
  97 MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
  98 MODULE_LICENSE("GPL");