1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * mpls tunnels An implementation mpls tunnels using the light weight tunnel 4 * infrastructure 5 * 6 * Authors: Roopa Prabhu, <roopa@cumulusnetworks.com> 7 */ 8 #include <linux/types.h> 9 #include <linux/skbuff.h> 10 #include <linux/net.h> 11 #include <linux/module.h> 12 #include <linux/mpls.h> 13 #include <linux/vmalloc.h> 14 #include <net/ip.h> 15 #include <net/dst.h> 16 #include <net/lwtunnel.h> 17 #include <net/netevent.h> 18 #include <net/netns/generic.h> 19 #include <net/ip6_fib.h> 20 #include <net/route.h> 21 #include <net/mpls_iptunnel.h> 22 #include <linux/mpls_iptunnel.h> 23 #include "internal.h" 24 25 static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = { 26 [MPLS_IPTUNNEL_DST] = { .len = sizeof(u32) }, 27 [MPLS_IPTUNNEL_TTL] = { .type = NLA_U8 }, 28 }; 29 30 static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en) 31 { 32 /* The size of the layer 2.5 labels to be added for this route */ 33 return en->labels * sizeof(struct mpls_shim_hdr); 34 } 35 36 static int mpls_xmit(struct sk_buff *skb) 37 { 38 struct mpls_iptunnel_encap *tun_encap_info; 39 struct mpls_shim_hdr *hdr; 40 struct net_device *out_dev; 41 unsigned int hh_len; 42 unsigned int new_header_size; 43 unsigned int mtu; 44 struct dst_entry *dst = skb_dst(skb); 45 struct rtable *rt = NULL; 46 struct rt6_info *rt6 = NULL; 47 struct mpls_dev *out_mdev; 48 struct net *net; 49 int err = 0; 50 bool bos; 51 int i; 52 unsigned int ttl; 53 54 /* Find the output device */ 55 out_dev = dst->dev; 56 net = dev_net(out_dev); 57 58 skb_orphan(skb); 59 60 if (!mpls_output_possible(out_dev) || 61 !dst->lwtstate || skb_warn_if_lro(skb)) 62 goto drop; 63 64 skb_forward_csum(skb); 65 66 tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate); 67 68 /* Obtain the ttl using the following set of rules. 69 * 70 * LWT ttl propagation setting: 71 * - disabled => use default TTL value from LWT 72 * - enabled => use TTL value from IPv4/IPv6 header 73 * - default => 74 * Global ttl propagation setting: 75 * - disabled => use default TTL value from global setting 76 * - enabled => use TTL value from IPv4/IPv6 header 77 */ 78 if (dst->ops->family == AF_INET) { 79 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED) 80 ttl = tun_encap_info->default_ttl; 81 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT && 82 !net->mpls.ip_ttl_propagate) 83 ttl = net->mpls.default_ttl; 84 else 85 ttl = ip_hdr(skb)->ttl; 86 rt = (struct rtable *)dst; 87 } else if (dst->ops->family == AF_INET6) { 88 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED) 89 ttl = tun_encap_info->default_ttl; 90 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT && 91 !net->mpls.ip_ttl_propagate) 92 ttl = net->mpls.default_ttl; 93 else 94 ttl = ipv6_hdr(skb)->hop_limit; 95 rt6 = (struct rt6_info *)dst; 96 } else { 97 goto drop; 98 } 99 100 /* Verify the destination can hold the packet */ 101 new_header_size = mpls_encap_size(tun_encap_info); 102 mtu = mpls_dev_mtu(out_dev); 103 if (mpls_pkt_too_big(skb, mtu - new_header_size)) 104 goto drop; 105 106 hh_len = LL_RESERVED_SPACE(out_dev); 107 if (!out_dev->header_ops) 108 hh_len = 0; 109 110 /* Ensure there is enough space for the headers in the skb */ 111 if (skb_cow(skb, hh_len + new_header_size)) 112 goto drop; 113 114 skb_set_inner_protocol(skb, skb->protocol); 115 skb_reset_inner_network_header(skb); 116 117 skb_push(skb, new_header_size); 118 119 skb_reset_network_header(skb); 120 121 skb->dev = out_dev; 122 skb->protocol = htons(ETH_P_MPLS_UC); 123 124 /* Push the new labels */ 125 hdr = mpls_hdr(skb); 126 bos = true; 127 for (i = tun_encap_info->labels - 1; i >= 0; i--) { 128 hdr[i] = mpls_entry_encode(tun_encap_info->label[i], 129 ttl, 0, bos); 130 bos = false; 131 } 132 133 mpls_stats_inc_outucastpkts(out_dev, skb); 134 135 if (rt) { 136 if (rt->rt_gw_family == AF_INET6) 137 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt->rt_gw6, 138 skb); 139 else 140 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gw4, 141 skb); 142 } else if (rt6) { 143 if (ipv6_addr_v4mapped(&rt6->rt6i_gateway)) { 144 /* 6PE (RFC 4798) */ 145 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt6->rt6i_gateway.s6_addr32[3], 146 skb); 147 } else 148 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway, 149 skb); 150 } 151 if (err) 152 net_dbg_ratelimited("%s: packet transmission failed: %d\n", 153 __func__, err); 154 155 return LWTUNNEL_XMIT_DONE; 156 157 drop: 158 out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL; 159 if (out_mdev) 160 MPLS_INC_STATS(out_mdev, tx_errors); 161 kfree_skb(skb); 162 return -EINVAL; 163 } 164 165 static int mpls_build_state(struct nlattr *nla, 166 unsigned int family, const void *cfg, 167 struct lwtunnel_state **ts, 168 struct netlink_ext_ack *extack) 169 { 170 struct mpls_iptunnel_encap *tun_encap_info; 171 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1]; 172 struct lwtunnel_state *newts; 173 u8 n_labels; 174 int ret; 175 176 ret = nla_parse_nested_deprecated(tb, MPLS_IPTUNNEL_MAX, nla, 177 mpls_iptunnel_policy, extack); 178 if (ret < 0) 179 return ret; 180 181 if (!tb[MPLS_IPTUNNEL_DST]) { 182 NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing"); 183 return -EINVAL; 184 } 185 186 /* determine number of labels */ 187 if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS, 188 &n_labels, NULL, extack)) 189 return -EINVAL; 190 191 newts = lwtunnel_state_alloc(struct_size(tun_encap_info, label, 192 n_labels)); 193 if (!newts) 194 return -ENOMEM; 195 196 tun_encap_info = mpls_lwtunnel_encap(newts); 197 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels, 198 &tun_encap_info->labels, tun_encap_info->label, 199 extack); 200 if (ret) 201 goto errout; 202 203 tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT; 204 205 if (tb[MPLS_IPTUNNEL_TTL]) { 206 tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]); 207 /* TTL 0 implies propagate from IP header */ 208 tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ? 209 MPLS_TTL_PROP_DISABLED : 210 MPLS_TTL_PROP_ENABLED; 211 } 212 213 newts->type = LWTUNNEL_ENCAP_MPLS; 214 newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT; 215 newts->headroom = mpls_encap_size(tun_encap_info); 216 217 *ts = newts; 218 219 return 0; 220 221 errout: 222 kfree(newts); 223 *ts = NULL; 224 225 return ret; 226 } 227 228 static int mpls_fill_encap_info(struct sk_buff *skb, 229 struct lwtunnel_state *lwtstate) 230 { 231 struct mpls_iptunnel_encap *tun_encap_info; 232 233 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 234 235 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels, 236 tun_encap_info->label)) 237 goto nla_put_failure; 238 239 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT && 240 nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl)) 241 goto nla_put_failure; 242 243 return 0; 244 245 nla_put_failure: 246 return -EMSGSIZE; 247 } 248 249 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate) 250 { 251 struct mpls_iptunnel_encap *tun_encap_info; 252 int nlsize; 253 254 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 255 256 nlsize = nla_total_size(tun_encap_info->labels * 4); 257 258 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT) 259 nlsize += nla_total_size(1); 260 261 return nlsize; 262 } 263 264 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 265 { 266 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a); 267 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b); 268 int l; 269 270 if (a_hdr->labels != b_hdr->labels || 271 a_hdr->ttl_propagate != b_hdr->ttl_propagate || 272 a_hdr->default_ttl != b_hdr->default_ttl) 273 return 1; 274 275 for (l = 0; l < a_hdr->labels; l++) 276 if (a_hdr->label[l] != b_hdr->label[l]) 277 return 1; 278 return 0; 279 } 280 281 static const struct lwtunnel_encap_ops mpls_iptun_ops = { 282 .build_state = mpls_build_state, 283 .xmit = mpls_xmit, 284 .fill_encap = mpls_fill_encap_info, 285 .get_encap_size = mpls_encap_nlsize, 286 .cmp_encap = mpls_encap_cmp, 287 .owner = THIS_MODULE, 288 }; 289 290 static int __init mpls_iptunnel_init(void) 291 { 292 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 293 } 294 module_init(mpls_iptunnel_init); 295 296 static void __exit mpls_iptunnel_exit(void) 297 { 298 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 299 } 300 module_exit(mpls_iptunnel_exit); 301 302 MODULE_ALIAS_RTNL_LWT(MPLS); 303 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); 304 MODULE_LICENSE("GPL v2"); 305