linux/net/mpls/mpls_iptunnel.c
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   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
  30static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
  31        [MPLS_IPTUNNEL_DST]     = { .len = sizeof(u32) },
  32        [MPLS_IPTUNNEL_TTL]     = { .type = NLA_U8 },
  33};
  34
  35static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
  36{
  37        /* The size of the layer 2.5 labels to be added for this route */
  38        return en->labels * sizeof(struct mpls_shim_hdr);
  39}
  40
  41static int mpls_xmit(struct sk_buff *skb)
  42{
  43        struct mpls_iptunnel_encap *tun_encap_info;
  44        struct mpls_shim_hdr *hdr;
  45        struct net_device *out_dev;
  46        unsigned int hh_len;
  47        unsigned int new_header_size;
  48        unsigned int mtu;
  49        struct dst_entry *dst = skb_dst(skb);
  50        struct rtable *rt = NULL;
  51        struct rt6_info *rt6 = NULL;
  52        struct mpls_dev *out_mdev;
  53        struct net *net;
  54        int err = 0;
  55        bool bos;
  56        int i;
  57        unsigned int ttl;
  58
  59        /* Find the output device */
  60        out_dev = dst->dev;
  61        net = dev_net(out_dev);
  62
  63        skb_orphan(skb);
  64
  65        if (!mpls_output_possible(out_dev) ||
  66            !dst->lwtstate || skb_warn_if_lro(skb))
  67                goto drop;
  68
  69        skb_forward_csum(skb);
  70
  71        tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
  72
  73        /* Obtain the ttl using the following set of rules.
  74         *
  75         * LWT ttl propagation setting:
  76         *  - disabled => use default TTL value from LWT
  77         *  - enabled  => use TTL value from IPv4/IPv6 header
  78         *  - default  =>
  79         *   Global ttl propagation setting:
  80         *    - disabled => use default TTL value from global setting
  81         *    - enabled => use TTL value from IPv4/IPv6 header
  82         */
  83        if (dst->ops->family == AF_INET) {
  84                if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
  85                        ttl = tun_encap_info->default_ttl;
  86                else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
  87                         !net->mpls.ip_ttl_propagate)
  88                        ttl = net->mpls.default_ttl;
  89                else
  90                        ttl = ip_hdr(skb)->ttl;
  91                rt = (struct rtable *)dst;
  92        } else if (dst->ops->family == AF_INET6) {
  93                if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
  94                        ttl = tun_encap_info->default_ttl;
  95                else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
  96                         !net->mpls.ip_ttl_propagate)
  97                        ttl = net->mpls.default_ttl;
  98                else
  99                        ttl = ipv6_hdr(skb)->hop_limit;
 100                rt6 = (struct rt6_info *)dst;
 101        } else {
 102                goto drop;
 103        }
 104
 105        /* Verify the destination can hold the packet */
 106        new_header_size = mpls_encap_size(tun_encap_info);
 107        mtu = mpls_dev_mtu(out_dev);
 108        if (mpls_pkt_too_big(skb, mtu - new_header_size))
 109                goto drop;
 110
 111        hh_len = LL_RESERVED_SPACE(out_dev);
 112        if (!out_dev->header_ops)
 113                hh_len = 0;
 114
 115        /* Ensure there is enough space for the headers in the skb */
 116        if (skb_cow(skb, hh_len + new_header_size))
 117                goto drop;
 118
 119        skb_set_inner_protocol(skb, skb->protocol);
 120        skb_reset_inner_network_header(skb);
 121
 122        skb_push(skb, new_header_size);
 123
 124        skb_reset_network_header(skb);
 125
 126        skb->dev = out_dev;
 127        skb->protocol = htons(ETH_P_MPLS_UC);
 128
 129        /* Push the new labels */
 130        hdr = mpls_hdr(skb);
 131        bos = true;
 132        for (i = tun_encap_info->labels - 1; i >= 0; i--) {
 133                hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
 134                                           ttl, 0, bos);
 135                bos = false;
 136        }
 137
 138        mpls_stats_inc_outucastpkts(out_dev, skb);
 139
 140        if (rt)
 141                err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
 142                                 skb);
 143        else if (rt6) {
 144                if (ipv6_addr_v4mapped(&rt6->rt6i_gateway)) {
 145                        /* 6PE (RFC 4798) */
 146                        err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt6->rt6i_gateway.s6_addr32[3],
 147                                         skb);
 148                } else
 149                        err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
 150                                         skb);
 151        }
 152        if (err)
 153                net_dbg_ratelimited("%s: packet transmission failed: %d\n",
 154                                    __func__, err);
 155
 156        return LWTUNNEL_XMIT_DONE;
 157
 158drop:
 159        out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
 160        if (out_mdev)
 161                MPLS_INC_STATS(out_mdev, tx_errors);
 162        kfree_skb(skb);
 163        return -EINVAL;
 164}
 165
 166static int mpls_build_state(struct nlattr *nla,
 167                            unsigned int family, const void *cfg,
 168                            struct lwtunnel_state **ts,
 169                            struct netlink_ext_ack *extack)
 170{
 171        struct mpls_iptunnel_encap *tun_encap_info;
 172        struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
 173        struct lwtunnel_state *newts;
 174        u8 n_labels;
 175        int ret;
 176
 177        ret = nla_parse_nested_deprecated(tb, MPLS_IPTUNNEL_MAX, nla,
 178                                          mpls_iptunnel_policy, extack);
 179        if (ret < 0)
 180                return ret;
 181
 182        if (!tb[MPLS_IPTUNNEL_DST]) {
 183                NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing");
 184                return -EINVAL;
 185        }
 186
 187        /* determine number of labels */
 188        if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
 189                           &n_labels, NULL, extack))
 190                return -EINVAL;
 191
 192        newts = lwtunnel_state_alloc(sizeof(*tun_encap_info) +
 193                                     n_labels * sizeof(u32));
 194        if (!newts)
 195                return -ENOMEM;
 196
 197        tun_encap_info = mpls_lwtunnel_encap(newts);
 198        ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels,
 199                             &tun_encap_info->labels, tun_encap_info->label,
 200                             extack);
 201        if (ret)
 202                goto errout;
 203
 204        tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT;
 205
 206        if (tb[MPLS_IPTUNNEL_TTL]) {
 207                tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]);
 208                /* TTL 0 implies propagate from IP header */
 209                tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ?
 210                        MPLS_TTL_PROP_DISABLED :
 211                        MPLS_TTL_PROP_ENABLED;
 212        }
 213
 214        newts->type = LWTUNNEL_ENCAP_MPLS;
 215        newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
 216        newts->headroom = mpls_encap_size(tun_encap_info);
 217
 218        *ts = newts;
 219
 220        return 0;
 221
 222errout:
 223        kfree(newts);
 224        *ts = NULL;
 225
 226        return ret;
 227}
 228
 229static int mpls_fill_encap_info(struct sk_buff *skb,
 230                                struct lwtunnel_state *lwtstate)
 231{
 232        struct mpls_iptunnel_encap *tun_encap_info;
 233        
 234        tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 235
 236        if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
 237                           tun_encap_info->label))
 238                goto nla_put_failure;
 239
 240        if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT &&
 241            nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl))
 242                goto nla_put_failure;
 243
 244        return 0;
 245
 246nla_put_failure:
 247        return -EMSGSIZE;
 248}
 249
 250static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
 251{
 252        struct mpls_iptunnel_encap *tun_encap_info;
 253        int nlsize;
 254
 255        tun_encap_info = mpls_lwtunnel_encap(lwtstate);
 256
 257        nlsize = nla_total_size(tun_encap_info->labels * 4);
 258
 259        if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT)
 260                nlsize += nla_total_size(1);
 261
 262        return nlsize;
 263}
 264
 265static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 266{
 267        struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
 268        struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
 269        int l;
 270
 271        if (a_hdr->labels != b_hdr->labels ||
 272            a_hdr->ttl_propagate != b_hdr->ttl_propagate ||
 273            a_hdr->default_ttl != b_hdr->default_ttl)
 274                return 1;
 275
 276        for (l = 0; l < a_hdr->labels; l++)
 277                if (a_hdr->label[l] != b_hdr->label[l])
 278                        return 1;
 279        return 0;
 280}
 281
 282static const struct lwtunnel_encap_ops mpls_iptun_ops = {
 283        .build_state = mpls_build_state,
 284        .xmit = mpls_xmit,
 285        .fill_encap = mpls_fill_encap_info,
 286        .get_encap_size = mpls_encap_nlsize,
 287        .cmp_encap = mpls_encap_cmp,
 288        .owner = THIS_MODULE,
 289};
 290
 291static int __init mpls_iptunnel_init(void)
 292{
 293        return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 294}
 295module_init(mpls_iptunnel_init);
 296
 297static void __exit mpls_iptunnel_exit(void)
 298{
 299        lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
 300}
 301module_exit(mpls_iptunnel_exit);
 302
 303MODULE_ALIAS_RTNL_LWT(MPLS);
 304MODULE_SOFTDEP("post: mpls_gso");
 305MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
 306MODULE_LICENSE("GPL v2");
 307