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_FIXEDID |
  35                                   SKB_GSO_TCP_ECN)))
  36                 goto out;
  37
  38         /* Setup inner SKB. */
  39         mpls_protocol = skb->protocol;
  40         skb->protocol = skb->inner_protocol;
  41
  42         /* Push back the mac header that skb_mac_gso_segment() has pulled.
  43          * It will be re-pulled by the call to skb_mac_gso_segment() below
  44          */
  45         __skb_push(skb, skb->mac_len);
  46
  47         /* Segment inner packet. */
  48         mpls_features = skb->dev->mpls_features & features;
  49         segs = skb_mac_gso_segment(skb, mpls_features);
  50
  51
  52         /* Restore outer protocol. */
  53         skb->protocol = mpls_protocol;
  54
  55         /* Re-pull the mac header that the call to skb_mac_gso_segment()
  56          * above pulled.  It will be re-pushed after returning
  57          * skb_mac_gso_segment(), an indirect caller of this function.
  58          */
  59         __skb_pull(skb, skb->data - skb_mac_header(skb));
  60 out:
  61         return segs;
  62 }
  63
  64 static struct packet_offload mpls_mc_offload __read_mostly = {
  65         .type = cpu_to_be16(ETH_P_MPLS_MC),
  66         .priority = 15,
  67         .callbacks = {
  68                 .gso_segment    =       mpls_gso_segment,
  69         },
  70 };
  71
  72 static struct packet_offload mpls_uc_offload __read_mostly = {
  73         .type = cpu_to_be16(ETH_P_MPLS_UC),
  74         .priority = 15,
  75         .callbacks = {
  76                 .gso_segment    =       mpls_gso_segment,
  77         },
  78 };
  79
  80 static int __init mpls_gso_init(void)
  81 {
  82         pr_info("MPLS GSO support\n");
  83
  84         dev_add_offload(&mpls_uc_offload);
  85         dev_add_offload(&mpls_mc_offload);
  86
  87         return 0;
  88 }
  89
  90 static void __exit mpls_gso_exit(void)
  91 {
  92         dev_remove_offload(&mpls_uc_offload);
  93         dev_remove_offload(&mpls_mc_offload);
  94 }
  95
  96 module_init(mpls_gso_init);
  97 module_exit(mpls_gso_exit);
  98
  99 MODULE_DESCRIPTION("MPLS GSO support");
 100 MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
 101 MODULE_LICENSE("GPL");