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