net/nsh/nsh.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Network Service Header
   4  *
   5  * Copyright (c) 2017 Red Hat, Inc. -- Jiri Benc <jbenc@redhat.com>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/skbuff.h>
  11 #include <net/nsh.h>
  12 #include <net/tun_proto.h>
  13
  14 int nsh_push(struct sk_buff *skb, const struct nshhdr *pushed_nh)
  15 {
  16         struct nshhdr *nh;
  17         size_t length = nsh_hdr_len(pushed_nh);
  18         u8 next_proto;
  19
  20         if (skb->mac_len) {
  21                 next_proto = TUN_P_ETHERNET;
  22         } else {
  23                 next_proto = tun_p_from_eth_p(skb->protocol);
  24                 if (!next_proto)
  25                         return -EAFNOSUPPORT;
  26         }
  27
  28         /* Add the NSH header */
  29         if (skb_cow_head(skb, length) < 0)
  30                 return -ENOMEM;
  31
  32         skb_push(skb, length);
  33         nh = (struct nshhdr *)(skb->data);
  34         memcpy(nh, pushed_nh, length);
  35         nh->np = next_proto;
  36         skb_postpush_rcsum(skb, nh, length);
  37
  38         skb->protocol = htons(ETH_P_NSH);
  39         skb_reset_mac_header(skb);
  40         skb_reset_network_header(skb);
  41         skb_reset_mac_len(skb);
  42
  43         return 0;
  44 }
  45 EXPORT_SYMBOL_GPL(nsh_push);
  46
  47 int nsh_pop(struct sk_buff *skb)
  48 {
  49         struct nshhdr *nh;
  50         size_t length;
  51         __be16 inner_proto;
  52
  53         if (!pskb_may_pull(skb, NSH_BASE_HDR_LEN))
  54                 return -ENOMEM;
  55         nh = (struct nshhdr *)(skb->data);
  56         length = nsh_hdr_len(nh);
  57         if (length < NSH_BASE_HDR_LEN)
  58                 return -EINVAL;
  59         inner_proto = tun_p_to_eth_p(nh->np);
  60         if (!pskb_may_pull(skb, length))
  61                 return -ENOMEM;
  62
  63         if (!inner_proto)
  64                 return -EAFNOSUPPORT;
  65
  66         skb_pull_rcsum(skb, length);
  67         skb_reset_mac_header(skb);
  68         skb_reset_network_header(skb);
  69         skb_reset_mac_len(skb);
  70         skb->protocol = inner_proto;
  71
  72         return 0;
  73 }
  74 EXPORT_SYMBOL_GPL(nsh_pop);
  75
  76 static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
  77                                        netdev_features_t features)
  78 {
  79         struct sk_buff *segs = ERR_PTR(-EINVAL);
  80         unsigned int nsh_len, mac_len;
  81         __be16 proto;
  82         int nhoff;
  83
  84         skb_reset_network_header(skb);
  85
  86         nhoff = skb->network_header - skb->mac_header;
  87         mac_len = skb->mac_len;
  88
  89         if (unlikely(!pskb_may_pull(skb, NSH_BASE_HDR_LEN)))
  90                 goto out;
  91         nsh_len = nsh_hdr_len(nsh_hdr(skb));
  92         if (nsh_len < NSH_BASE_HDR_LEN)
  93                 goto out;
  94         if (unlikely(!pskb_may_pull(skb, nsh_len)))
  95                 goto out;
  96
  97         proto = tun_p_to_eth_p(nsh_hdr(skb)->np);
  98         if (!proto)
  99                 goto out;
 100
 101         __skb_pull(skb, nsh_len);
 102
 103         skb_reset_mac_header(skb);
 104         skb->mac_len = proto == htons(ETH_P_TEB) ? ETH_HLEN : 0;
 105         skb->protocol = proto;
 106
 107         features &= NETIF_F_SG;
 108         segs = skb_mac_gso_segment(skb, features);
 109         if (IS_ERR_OR_NULL(segs)) {
 110                 skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len,
 111                                      skb->network_header - nhoff,
 112                                      mac_len);
 113                 goto out;
 114         }
 115
 116         for (skb = segs; skb; skb = skb->next) {
 117                 skb->protocol = htons(ETH_P_NSH);
 118                 __skb_push(skb, nsh_len);
 119                 skb_set_mac_header(skb, -nhoff);
 120                 skb->network_header = skb->mac_header + mac_len;
 121                 skb->mac_len = mac_len;
 122         }
 123
 124 out:
 125         return segs;
 126 }
 127
 128 static struct packet_offload nsh_packet_offload __read_mostly = {
 129         .type = htons(ETH_P_NSH),
 130         .priority = 15,
 131         .callbacks = {
 132                 .gso_segment = nsh_gso_segment,
 133         },
 134 };
 135
 136 static int __init nsh_init_module(void)
 137 {
 138         dev_add_offload(&nsh_packet_offload);
 139         return 0;
 140 }
 141
 142 static void __exit nsh_cleanup_module(void)
 143 {
 144         dev_remove_offload(&nsh_packet_offload);
 145 }
 146
 147 module_init(nsh_init_module);
 148 module_exit(nsh_cleanup_module);
 149
 150 MODULE_AUTHOR("Jiri Benc <jbenc@redhat.com>");
 151 MODULE_DESCRIPTION("NSH protocol");
 152 MODULE_LICENSE("GPL v2");