net/mpls/mpls_iptunnel.c

   1 /*
   2  * mpls tunnels An implementation mpls tunnels using the light weight tunnel
   3  *              infrastructure
   4  *
   5  * Authors:     Roopa Prabhu, <roopa@cumulusnetworks.com>
   6  *
   7  *              This program is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  */
  13 #include <linux/types.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/net.h>
  16 #include <linux/module.h>
  17 #include <linux/mpls.h>
  18 #include <linux/vmalloc.h>
  19 #include <net/ip.h>
  20 #include <net/dst.h>
  21 #include <net/lwtunnel.h>
  22 #include <net/netevent.h>
  23 #include <net/netns/generic.h>
  24 #include <net/ip6_fib.h>
  25 #include <net/route.h>
  26 #include <net/mpls_iptunnel.h>
  27 #include <linux/mpls_iptunnel.h>
  28 #include "internal.h"
  29
  30 static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
  31         [MPLS_IPTUNNEL_DST]     = { .type = NLA_U32 },
  32 };
  33
  34 static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
  35 {
  36         /* The size of the layer 2.5 labels to be added for this route */
  37         return en->labels * sizeof(struct mpls_shim_hdr);
  38 }
  39
  40 static int mpls_xmit(struct sk_buff *skb)
  41 {
  42         struct mpls_iptunnel_encap *tun_encap_info;
  43         struct mpls_shim_hdr *hdr;
  44         struct net_device *out_dev;
  45         unsigned int hh_len;
  46         unsigned int new_header_size;
  47         unsigned int mtu;
  48         struct dst_entry *dst = skb_dst(skb);
  49         struct rtable *rt = NULL;
  50         struct rt6_info *rt6 = NULL;
  51         int err = 0;
  52         bool bos;
  53         int i;
  54         unsigned int ttl;
  55
  56         /* Obtain the ttl */
  57         if (dst->ops->family == AF_INET) {
  58                 ttl = ip_hdr(skb)->ttl;
  59                 rt = (struct rtable *)dst;
  60         } else if (dst->ops->family == AF_INET6) {
  61                 ttl = ipv6_hdr(skb)->hop_limit;
  62                 rt6 = (struct rt6_info *)dst;
  63         } else {
  64                 goto drop;
  65         }
  66
  67         skb_orphan(skb);
  68
  69         /* Find the output device */
  70         out_dev = dst->dev;
  71         if (!mpls_output_possible(out_dev) ||
  72             !dst->lwtstate || skb_warn_if_lro(skb))
  73                 goto drop;
  74
  75         skb_forward_csum(skb);
  76
  77         tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
  78
  79         /* Verify the destination can hold the packet */
  80         new_header_size = mpls_encap_size(tun_encap_info);
  81         mtu = mpls_dev_mtu(out_dev);
  82         if (mpls_pkt_too_big(skb, mtu - new_header_size))
  83                 goto drop;
  84
  85         hh_len = LL_RESERVED_SPACE(out_dev);
  86         if (!out_dev->header_ops)
  87                 hh_len = 0;
  88
  89         /* Ensure there is enough space for the headers in the skb */
  90         if (skb_cow(skb, hh_len + new_header_size))
  91                 goto drop;
  92
  93         skb_set_inner_protocol(skb, skb->protocol);
  94         skb_reset_inner_network_header(skb);
  95
  96         skb_push(skb, new_header_size);
  97
  98         skb_reset_network_header(skb);
  99
 100         skb->dev = out_dev;
 101         skb->protocol = htons(ETH_P_MPLS_UC);
 102
 103         /* Push the new labels */
 104         hdr = mpls_hdr(skb);
 105         bos = true;
 106         for (i = tun_encap_info->labels - 1; i >= 0; i--) {
 107                 hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
 108                                            ttl, 0, bos);
 109                 bos = false;
 110         }
 111
 112         if (rt)
 113                 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
 114                                  skb);
 115         else if (rt6)
 116                 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
 117                                  skb);
 118         if (err)
 119                 net_dbg_ratelimited("%s: packet transmission failed: %d\n",
 120                                     __func__, err);
 121
 122         return LWTUNNEL_XMIT_DONE;
 123
 124 drop:
 125         kfree_skb(skb);
 126         return -EINVAL;
 127 }
 128
 129 static int mpls_build_state(struct net_device *dev, struct nlattr *nla,
 130                             unsigned int family, const void *cfg,
 131                             struct lwtunnel_state **ts)
 132 {
 133         struct mpls_iptunnel_encap *tun_encap_info;
 134         struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
 135         struct lwtunnel_state *newts;
 136         int tun_encap_info_len;
 137         int ret;
 138
 139         ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
 140                                mpls_iptunnel_policy);
 141         if (ret < 0)
 142                 return ret;
 143
 144         if (!tb[MPLS_IPTUNNEL_DST])
 145                 return -EINVAL;
 146
 147         tun_encap_info_len = sizeof(*tun_encap_info);
 148
 149         newts = lwtunnel_state_alloc(tun_encap_info_len);
 150         if (!newts)
 151                 return -ENOMEM;
 152
 153         newts->len = tun_encap_info_len;
 154         tun_encap_info = mpls_lwtunnel_encap(newts);
 155         ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
 156                              &tun_encap_info->labels, tun_encap_info->label);
 157         if (ret)
 158                 goto errout;
 159         newts->type = LWTUNNEL_ENCAP_MPLS;
 160         newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
 161         newts->headroom = mpls_encap_size(tun_encap_info);
 162
 163         *ts = newts;
 164
 165         return 0;
 166
 167 errout:
 168         kfree(newts);
 169         *ts = NULL;
 170
 171         return ret;
 172 }
 173
 174 static int mpls_fill_encap_info(struct sk_buff *skb,
 175                                 struct lwtunnel_state *lwtstate)
 176 {
 177         struct mpls_iptunnel_encap *tun_encap_info;
 178
 179         tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 180
 181         if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
 182                            tun_encap_info->label))
 183                 goto nla_put_failure;
 184
 185         return 0;
 186
 187 nla_put_failure:
 188         return -EMSGSIZE;
 189 }
 190
 191 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
 192 {
 193         struct mpls_iptunnel_encap *tun_encap_info;
 194
 195         tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 196
 197         return nla_total_size(tun_encap_info->labels * 4);
 198 }
 199
 200 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 201 {
 202         struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
 203         struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
 204         int l;
 205
 206         if (a_hdr->labels != b_hdr->labels)
 207                 return 1;
 208
 209         for (l = 0; l < MAX_NEW_LABELS; l++)
 210                 if (a_hdr->label[l] != b_hdr->label[l])
 211                         return 1;
 212         return 0;
 213 }
 214
 215 static const struct lwtunnel_encap_ops mpls_iptun_ops = {
 216         .build_state = mpls_build_state,
 217         .xmit = mpls_xmit,
 218         .fill_encap = mpls_fill_encap_info,
 219         .get_encap_size = mpls_encap_nlsize,
 220         .cmp_encap = mpls_encap_cmp,
 221         .owner = THIS_MODULE,
 222 };
 223
 224 static int __init mpls_iptunnel_init(void)
 225 {
 226         return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 227 }
 228 module_init(mpls_iptunnel_init);
 229
 230 static void __exit mpls_iptunnel_exit(void)
 231 {
 232         lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 233 }
 234 module_exit(mpls_iptunnel_exit);
 235
 236 MODULE_ALIAS_RTNL_LWT(MPLS);
 237 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
 238 MODULE_LICENSE("GPL v2");