net/mpls/mpls_gso.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      MPLS GSO Support
   4  *
   5  *      Authors: Simon Horman (horms@verge.net.au)
   6  *
   7  *      Based on: GSO portions of net/ipv4/gre.c
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/err.h>
  13 #include <linux/module.h>
  14 #include <linux/netdev_features.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/skbuff.h>
  17 #include <net/gso.h>
  18 #include <net/mpls.h>
  19
  20 static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
  21                                        netdev_features_t features)
  22 {
  23         struct sk_buff *segs = ERR_PTR(-EINVAL);
  24         u16 mac_offset = skb->mac_header;
  25         netdev_features_t mpls_features;
  26         u16 mac_len = skb->mac_len;
  27         __be16 mpls_protocol;
  28         unsigned int mpls_hlen;
  29
  30         if (!skb_inner_network_header_was_set(skb))
  31                 goto out;
  32
  33         skb_reset_network_header(skb);
  34         mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb);
  35         if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN))
  36                 goto out;
  37         if (unlikely(!pskb_may_pull(skb, mpls_hlen)))
  38                 goto out;
  39
  40         /* Setup inner SKB. */
  41         mpls_protocol = skb->protocol;
  42         skb->protocol = skb->inner_protocol;
  43
  44         __skb_pull(skb, mpls_hlen);
  45
  46         skb->mac_len = 0;
  47         skb_reset_mac_header(skb);
  48
  49         /* Segment inner packet. */
  50         mpls_features = skb->dev->mpls_features & features;
  51         segs = skb_mac_gso_segment(skb, mpls_features);
  52         if (IS_ERR_OR_NULL(segs)) {
  53                 skb_gso_error_unwind(skb, mpls_protocol, mpls_hlen, mac_offset,
  54                                      mac_len);
  55                 goto out;
  56         }
  57         skb = segs;
  58
  59         mpls_hlen += mac_len;
  60         do {
  61                 skb->mac_len = mac_len;
  62                 skb->protocol = mpls_protocol;
  63
  64                 skb_reset_inner_network_header(skb);
  65
  66                 __skb_push(skb, mpls_hlen);
  67
  68                 skb_reset_mac_header(skb);
  69                 skb_set_network_header(skb, mac_len);
  70         } while ((skb = skb->next));
  71
  72 out:
  73         return segs;
  74 }
  75
  76 static struct packet_offload mpls_mc_offload __read_mostly = {
  77         .type = cpu_to_be16(ETH_P_MPLS_MC),
  78         .priority = 15,
  79         .callbacks = {
  80                 .gso_segment    =       mpls_gso_segment,
  81         },
  82 };
  83
  84 static struct packet_offload mpls_uc_offload __read_mostly = {
  85         .type = cpu_to_be16(ETH_P_MPLS_UC),
  86         .priority = 15,
  87         .callbacks = {
  88                 .gso_segment    =       mpls_gso_segment,
  89         },
  90 };
  91
  92 static int __init mpls_gso_init(void)
  93 {
  94         pr_info("MPLS GSO support\n");
  95
  96         dev_add_offload(&mpls_uc_offload);
  97         dev_add_offload(&mpls_mc_offload);
  98
  99         return 0;
 100 }
 101
 102 static void __exit mpls_gso_exit(void)
 103 {
 104         dev_remove_offload(&mpls_uc_offload);
 105         dev_remove_offload(&mpls_mc_offload);
 106 }
 107
 108 module_init(mpls_gso_init);
 109 module_exit(mpls_gso_exit);
 110
 111 MODULE_DESCRIPTION("MPLS GSO support");
 112 MODULE_AUTHOR("Simon Horman <horms@verge.net.au>");
 113 MODULE_LICENSE("GPL");