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 int mpls_output(struct sock *sk, 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 (skb->protocol == htons(ETH_P_IP)) { 58 ttl = ip_hdr(skb)->ttl; 59 rt = (struct rtable *)dst; 60 } else if (skb->protocol == htons(ETH_P_IPV6)) { 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_push(skb, new_header_size); 94 skb_reset_network_header(skb); 95 96 skb->dev = out_dev; 97 skb->protocol = htons(ETH_P_MPLS_UC); 98 99 /* Push the new labels */ 100 hdr = mpls_hdr(skb); 101 bos = true; 102 for (i = tun_encap_info->labels - 1; i >= 0; i--) { 103 hdr[i] = mpls_entry_encode(tun_encap_info->label[i], 104 ttl, 0, bos); 105 bos = false; 106 } 107 108 if (rt) 109 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway, 110 skb); 111 else if (rt6) 112 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway, 113 skb); 114 if (err) 115 net_dbg_ratelimited("%s: packet transmission failed: %d\n", 116 __func__, err); 117 118 return 0; 119 120 drop: 121 kfree_skb(skb); 122 return -EINVAL; 123 } 124 125 static int mpls_build_state(struct net_device *dev, struct nlattr *nla, 126 unsigned int family, const void *cfg, 127 struct lwtunnel_state **ts) 128 { 129 struct mpls_iptunnel_encap *tun_encap_info; 130 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1]; 131 struct lwtunnel_state *newts; 132 int tun_encap_info_len; 133 int ret; 134 135 ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla, 136 mpls_iptunnel_policy); 137 if (ret < 0) 138 return ret; 139 140 if (!tb[MPLS_IPTUNNEL_DST]) 141 return -EINVAL; 142 143 tun_encap_info_len = sizeof(*tun_encap_info); 144 145 newts = lwtunnel_state_alloc(tun_encap_info_len); 146 if (!newts) 147 return -ENOMEM; 148 149 newts->len = tun_encap_info_len; 150 tun_encap_info = mpls_lwtunnel_encap(newts); 151 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS, 152 &tun_encap_info->labels, tun_encap_info->label); 153 if (ret) 154 goto errout; 155 newts->type = LWTUNNEL_ENCAP_MPLS; 156 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; 157 158 *ts = newts; 159 160 return 0; 161 162 errout: 163 kfree(newts); 164 *ts = NULL; 165 166 return ret; 167 } 168 169 static int mpls_fill_encap_info(struct sk_buff *skb, 170 struct lwtunnel_state *lwtstate) 171 { 172 struct mpls_iptunnel_encap *tun_encap_info; 173 174 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 175 176 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels, 177 tun_encap_info->label)) 178 goto nla_put_failure; 179 180 return 0; 181 182 nla_put_failure: 183 return -EMSGSIZE; 184 } 185 186 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate) 187 { 188 struct mpls_iptunnel_encap *tun_encap_info; 189 190 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 191 192 return nla_total_size(tun_encap_info->labels * 4); 193 } 194 195 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 196 { 197 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a); 198 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b); 199 int l; 200 201 if (a_hdr->labels != b_hdr->labels) 202 return 1; 203 204 for (l = 0; l < MAX_NEW_LABELS; l++) 205 if (a_hdr->label[l] != b_hdr->label[l]) 206 return 1; 207 return 0; 208 } 209 210 static const struct lwtunnel_encap_ops mpls_iptun_ops = { 211 .build_state = mpls_build_state, 212 .output = mpls_output, 213 .fill_encap = mpls_fill_encap_info, 214 .get_encap_size = mpls_encap_nlsize, 215 .cmp_encap = mpls_encap_cmp, 216 }; 217 218 static int __init mpls_iptunnel_init(void) 219 { 220 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 221 } 222 module_init(mpls_iptunnel_init); 223 224 static void __exit mpls_iptunnel_exit(void) 225 { 226 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 227 } 228 module_exit(mpls_iptunnel_exit); 229 230 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); 231 MODULE_LICENSE("GPL v2"); 232