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         struct mpls_dev *out_mdev;
  52         int err = 0;
  53         bool bos;
  54         int i;
  55         unsigned int ttl;
  56
  57         /* Find the output device */
  58         out_dev = dst->dev;
  59
  60         /* Obtain the ttl */
  61         if (dst->ops->family == AF_INET) {
  62                 ttl = ip_hdr(skb)->ttl;
  63                 rt = (struct rtable *)dst;
  64         } else if (dst->ops->family == AF_INET6) {
  65                 ttl = ipv6_hdr(skb)->hop_limit;
  66                 rt6 = (struct rt6_info *)dst;
  67         } else {
  68                 goto drop;
  69         }
  70
  71         skb_orphan(skb);
  72
  73         if (!mpls_output_possible(out_dev) ||
  74             !dst->lwtstate || skb_warn_if_lro(skb))
  75                 goto drop;
  76
  77         skb_forward_csum(skb);
  78
  79         tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
  80
  81         /* Verify the destination can hold the packet */
  82         new_header_size = mpls_encap_size(tun_encap_info);
  83         mtu = mpls_dev_mtu(out_dev);
  84         if (mpls_pkt_too_big(skb, mtu - new_header_size))
  85                 goto drop;
  86
  87         hh_len = LL_RESERVED_SPACE(out_dev);
  88         if (!out_dev->header_ops)
  89                 hh_len = 0;
  90
  91         /* Ensure there is enough space for the headers in the skb */
  92         if (skb_cow(skb, hh_len + new_header_size))
  93                 goto drop;
  94
  95         skb_set_inner_protocol(skb, skb->protocol);
  96         skb_reset_inner_network_header(skb);
  97
  98         skb_push(skb, new_header_size);
  99
 100         skb_reset_network_header(skb);
 101
 102         skb->dev = out_dev;
 103         skb->protocol = htons(ETH_P_MPLS_UC);
 104
 105         /* Push the new labels */
 106         hdr = mpls_hdr(skb);
 107         bos = true;
 108         for (i = tun_encap_info->labels - 1; i >= 0; i--) {
 109                 hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
 110                                            ttl, 0, bos);
 111                 bos = false;
 112         }
 113
 114         mpls_stats_inc_outucastpkts(out_dev, skb);
 115
 116         if (rt)
 117                 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
 118                                  skb);
 119         else if (rt6)
 120                 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
 121                                  skb);
 122         if (err)
 123                 net_dbg_ratelimited("%s: packet transmission failed: %d\n",
 124                                     __func__, err);
 125
 126         return LWTUNNEL_XMIT_DONE;
 127
 128 drop:
 129         out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
 130         if (out_mdev)
 131                 MPLS_INC_STATS(out_mdev, tx_errors);
 132         kfree_skb(skb);
 133         return -EINVAL;
 134 }
 135
 136 static int mpls_build_state(struct nlattr *nla,
 137                             unsigned int family, const void *cfg,
 138                             struct lwtunnel_state **ts)
 139 {
 140         struct mpls_iptunnel_encap *tun_encap_info;
 141         struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
 142         struct lwtunnel_state *newts;
 143         int ret;
 144
 145         ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
 146                                mpls_iptunnel_policy);
 147         if (ret < 0)
 148                 return ret;
 149
 150         if (!tb[MPLS_IPTUNNEL_DST])
 151                 return -EINVAL;
 152
 153
 154         newts = lwtunnel_state_alloc(sizeof(*tun_encap_info));
 155         if (!newts)
 156                 return -ENOMEM;
 157
 158         tun_encap_info = mpls_lwtunnel_encap(newts);
 159         ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
 160                              &tun_encap_info->labels, tun_encap_info->label);
 161         if (ret)
 162                 goto errout;
 163         newts->type = LWTUNNEL_ENCAP_MPLS;
 164         newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
 165         newts->headroom = mpls_encap_size(tun_encap_info);
 166
 167         *ts = newts;
 168
 169         return 0;
 170
 171 errout:
 172         kfree(newts);
 173         *ts = NULL;
 174
 175         return ret;
 176 }
 177
 178 static int mpls_fill_encap_info(struct sk_buff *skb,
 179                                 struct lwtunnel_state *lwtstate)
 180 {
 181         struct mpls_iptunnel_encap *tun_encap_info;
 182
 183         tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 184
 185         if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
 186                            tun_encap_info->label))
 187                 goto nla_put_failure;
 188
 189         return 0;
 190
 191 nla_put_failure:
 192         return -EMSGSIZE;
 193 }
 194
 195 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
 196 {
 197         struct mpls_iptunnel_encap *tun_encap_info;
 198
 199         tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 200
 201         return nla_total_size(tun_encap_info->labels * 4);
 202 }
 203
 204 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 205 {
 206         struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
 207         struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
 208         int l;
 209
 210         if (a_hdr->labels != b_hdr->labels)
 211                 return 1;
 212
 213         for (l = 0; l < MAX_NEW_LABELS; l++)
 214                 if (a_hdr->label[l] != b_hdr->label[l])
 215                         return 1;
 216         return 0;
 217 }
 218
 219 static const struct lwtunnel_encap_ops mpls_iptun_ops = {
 220         .build_state = mpls_build_state,
 221         .xmit = mpls_xmit,
 222         .fill_encap = mpls_fill_encap_info,
 223         .get_encap_size = mpls_encap_nlsize,
 224         .cmp_encap = mpls_encap_cmp,
 225         .owner = THIS_MODULE,
 226 };
 227
 228 static int __init mpls_iptunnel_init(void)
 229 {
 230         return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 231 }
 232 module_init(mpls_iptunnel_init);
 233
 234 static void __exit mpls_iptunnel_exit(void)
 235 {
 236         lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 237 }
 238 module_exit(mpls_iptunnel_exit);
 239
 240 MODULE_ALIAS_RTNL_LWT(MPLS);
 241 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
 242 MODULE_LICENSE("GPL v2");