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 [MPLS_IPTUNNEL_TTL] = { .type = NLA_U8 }, 33 }; 34 35 static 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 41 static 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; 157 158 drop: 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 } 165 166 static 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(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(struct_size(tun_encap_info, label, 193 n_labels)); 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; 221 222 errout: 223 kfree(newts); 224 *ts = NULL; 225 226 return ret; 227 } 228 229 static 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; 245 246 nla_put_failure: 247 return -EMSGSIZE; 248 } 249 250 static 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 } 264 265 static 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 } 281 282 static 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 }; 290 291 static int __init mpls_iptunnel_init(void) 292 { 293 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 294 } 295 module_init(mpls_iptunnel_init); 296 297 static void __exit mpls_iptunnel_exit(void) 298 { 299 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 300 } 301 module_exit(mpls_iptunnel_exit); 302 303 MODULE_ALIAS_RTNL_LWT(MPLS); 304 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); 305 MODULE_LICENSE("GPL v2"); 306