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 if (!mpls_output_possible(out_dev) || 59 !dst->lwtstate || skb_warn_if_lro(skb)) 60 goto drop; 61 62 skb_forward_csum(skb); 63 64 tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate); 65 66 /* Obtain the ttl using the following set of rules. 67 * 68 * LWT ttl propagation setting: 69 * - disabled => use default TTL value from LWT 70 * - enabled => use TTL value from IPv4/IPv6 header 71 * - default => 72 * Global ttl propagation setting: 73 * - disabled => use default TTL value from global setting 74 * - enabled => use TTL value from IPv4/IPv6 header 75 */ 76 if (dst->ops->family == AF_INET) { 77 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED) 78 ttl = tun_encap_info->default_ttl; 79 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT && 80 !net->mpls.ip_ttl_propagate) 81 ttl = net->mpls.default_ttl; 82 else 83 ttl = ip_hdr(skb)->ttl; 84 rt = dst_rtable(dst); 85 } else if (dst->ops->family == AF_INET6) { 86 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED) 87 ttl = tun_encap_info->default_ttl; 88 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT && 89 !net->mpls.ip_ttl_propagate) 90 ttl = net->mpls.default_ttl; 91 else 92 ttl = ipv6_hdr(skb)->hop_limit; 93 rt6 = dst_rt6_info(dst); 94 } else { 95 goto drop; 96 } 97 98 /* Verify the destination can hold the packet */ 99 new_header_size = mpls_encap_size(tun_encap_info); 100 mtu = mpls_dev_mtu(out_dev); 101 if (mpls_pkt_too_big(skb, mtu - new_header_size)) 102 goto drop; 103 104 hh_len = LL_RESERVED_SPACE(out_dev); 105 if (!out_dev->header_ops) 106 hh_len = 0; 107 108 /* Ensure there is enough space for the headers in the skb */ 109 if (skb_cow(skb, hh_len + new_header_size)) 110 goto drop; 111 112 skb_set_inner_protocol(skb, skb->protocol); 113 skb_reset_inner_network_header(skb); 114 115 skb_push(skb, new_header_size); 116 117 skb_reset_network_header(skb); 118 119 skb->dev = out_dev; 120 skb->protocol = htons(ETH_P_MPLS_UC); 121 122 /* Push the new labels */ 123 hdr = mpls_hdr(skb); 124 bos = true; 125 for (i = tun_encap_info->labels - 1; i >= 0; i--) { 126 hdr[i] = mpls_entry_encode(tun_encap_info->label[i], 127 ttl, 0, bos); 128 bos = false; 129 } 130 131 mpls_stats_inc_outucastpkts(out_dev, skb); 132 133 if (rt) { 134 if (rt->rt_gw_family == AF_INET6) 135 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt->rt_gw6, 136 skb); 137 else 138 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gw4, 139 skb); 140 } else if (rt6) { 141 if (ipv6_addr_v4mapped(&rt6->rt6i_gateway)) { 142 /* 6PE (RFC 4798) */ 143 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt6->rt6i_gateway.s6_addr32[3], 144 skb); 145 } else 146 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway, 147 skb); 148 } 149 if (err) 150 net_dbg_ratelimited("%s: packet transmission failed: %d\n", 151 __func__, err); 152 153 return LWTUNNEL_XMIT_DONE; 154 155 drop: 156 out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL; 157 if (out_mdev) 158 MPLS_INC_STATS(out_mdev, tx_errors); 159 kfree_skb(skb); 160 return -EINVAL; 161 } 162 163 static int mpls_build_state(struct net *net, struct nlattr *nla, 164 unsigned int family, const void *cfg, 165 struct lwtunnel_state **ts, 166 struct netlink_ext_ack *extack) 167 { 168 struct mpls_iptunnel_encap *tun_encap_info; 169 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1]; 170 struct lwtunnel_state *newts; 171 u8 n_labels; 172 int ret; 173 174 ret = nla_parse_nested_deprecated(tb, MPLS_IPTUNNEL_MAX, nla, 175 mpls_iptunnel_policy, extack); 176 if (ret < 0) 177 return ret; 178 179 if (!tb[MPLS_IPTUNNEL_DST]) { 180 NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing"); 181 return -EINVAL; 182 } 183 184 /* determine number of labels */ 185 if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS, 186 &n_labels, NULL, extack)) 187 return -EINVAL; 188 189 newts = lwtunnel_state_alloc(struct_size(tun_encap_info, label, 190 n_labels)); 191 if (!newts) 192 return -ENOMEM; 193 194 tun_encap_info = mpls_lwtunnel_encap(newts); 195 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels, 196 &tun_encap_info->labels, tun_encap_info->label, 197 extack); 198 if (ret) 199 goto errout; 200 201 tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT; 202 203 if (tb[MPLS_IPTUNNEL_TTL]) { 204 tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]); 205 /* TTL 0 implies propagate from IP header */ 206 tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ? 207 MPLS_TTL_PROP_DISABLED : 208 MPLS_TTL_PROP_ENABLED; 209 } 210 211 newts->type = LWTUNNEL_ENCAP_MPLS; 212 newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT; 213 newts->headroom = mpls_encap_size(tun_encap_info); 214 215 *ts = newts; 216 217 return 0; 218 219 errout: 220 kfree(newts); 221 *ts = NULL; 222 223 return ret; 224 } 225 226 static int mpls_fill_encap_info(struct sk_buff *skb, 227 struct lwtunnel_state *lwtstate) 228 { 229 struct mpls_iptunnel_encap *tun_encap_info; 230 231 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 232 233 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels, 234 tun_encap_info->label)) 235 goto nla_put_failure; 236 237 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT && 238 nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl)) 239 goto nla_put_failure; 240 241 return 0; 242 243 nla_put_failure: 244 return -EMSGSIZE; 245 } 246 247 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate) 248 { 249 struct mpls_iptunnel_encap *tun_encap_info; 250 int nlsize; 251 252 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 253 254 nlsize = nla_total_size(tun_encap_info->labels * 4); 255 256 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT) 257 nlsize += nla_total_size(1); 258 259 return nlsize; 260 } 261 262 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 263 { 264 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a); 265 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b); 266 int l; 267 268 if (a_hdr->labels != b_hdr->labels || 269 a_hdr->ttl_propagate != b_hdr->ttl_propagate || 270 a_hdr->default_ttl != b_hdr->default_ttl) 271 return 1; 272 273 for (l = 0; l < a_hdr->labels; l++) 274 if (a_hdr->label[l] != b_hdr->label[l]) 275 return 1; 276 return 0; 277 } 278 279 static const struct lwtunnel_encap_ops mpls_iptun_ops = { 280 .build_state = mpls_build_state, 281 .xmit = mpls_xmit, 282 .fill_encap = mpls_fill_encap_info, 283 .get_encap_size = mpls_encap_nlsize, 284 .cmp_encap = mpls_encap_cmp, 285 .owner = THIS_MODULE, 286 }; 287 288 static int __init mpls_iptunnel_init(void) 289 { 290 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 291 } 292 module_init(mpls_iptunnel_init); 293 294 static void __exit mpls_iptunnel_exit(void) 295 { 296 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 297 } 298 module_exit(mpls_iptunnel_exit); 299 300 MODULE_ALIAS_RTNL_LWT(MPLS); 301 MODULE_SOFTDEP("post: mpls_gso"); 302 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); 303 MODULE_LICENSE("GPL v2"); 304