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 struct lwtunnel_state *lwtstate = NULL; 52 int err = 0; 53 bool bos; 54 int i; 55 unsigned int ttl; 56 57 /* Obtain the ttl */ 58 if (skb->protocol == htons(ETH_P_IP)) { 59 ttl = ip_hdr(skb)->ttl; 60 rt = (struct rtable *)dst; 61 lwtstate = rt->rt_lwtstate; 62 } else if (skb->protocol == htons(ETH_P_IPV6)) { 63 ttl = ipv6_hdr(skb)->hop_limit; 64 rt6 = (struct rt6_info *)dst; 65 lwtstate = rt6->rt6i_lwtstate; 66 } else { 67 goto drop; 68 } 69 70 skb_orphan(skb); 71 72 /* Find the output device */ 73 out_dev = dst->dev; 74 if (!mpls_output_possible(out_dev) || 75 !lwtstate || skb_warn_if_lro(skb)) 76 goto drop; 77 78 skb_forward_csum(skb); 79 80 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 81 82 /* Verify the destination can hold the packet */ 83 new_header_size = mpls_encap_size(tun_encap_info); 84 mtu = mpls_dev_mtu(out_dev); 85 if (mpls_pkt_too_big(skb, mtu - new_header_size)) 86 goto drop; 87 88 hh_len = LL_RESERVED_SPACE(out_dev); 89 if (!out_dev->header_ops) 90 hh_len = 0; 91 92 /* Ensure there is enough space for the headers in the skb */ 93 if (skb_cow(skb, hh_len + new_header_size)) 94 goto drop; 95 96 skb_push(skb, new_header_size); 97 skb_reset_network_header(skb); 98 99 skb->dev = out_dev; 100 skb->protocol = htons(ETH_P_MPLS_UC); 101 102 /* Push the new labels */ 103 hdr = mpls_hdr(skb); 104 bos = true; 105 for (i = tun_encap_info->labels - 1; i >= 0; i--) { 106 hdr[i] = mpls_entry_encode(tun_encap_info->label[i], 107 ttl, 0, bos); 108 bos = false; 109 } 110 111 if (rt) 112 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway, 113 skb); 114 else if (rt6) 115 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway, 116 skb); 117 if (err) 118 net_dbg_ratelimited("%s: packet transmission failed: %d\n", 119 __func__, err); 120 121 return 0; 122 123 drop: 124 kfree_skb(skb); 125 return -EINVAL; 126 } 127 128 static int mpls_build_state(struct net_device *dev, struct nlattr *nla, 129 struct lwtunnel_state **ts) 130 { 131 struct mpls_iptunnel_encap *tun_encap_info; 132 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1]; 133 struct lwtunnel_state *newts; 134 int tun_encap_info_len; 135 int ret; 136 137 ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla, 138 mpls_iptunnel_policy); 139 if (ret < 0) 140 return ret; 141 142 if (!tb[MPLS_IPTUNNEL_DST]) 143 return -EINVAL; 144 145 tun_encap_info_len = sizeof(*tun_encap_info); 146 147 newts = lwtunnel_state_alloc(tun_encap_info_len); 148 if (!newts) 149 return -ENOMEM; 150 151 newts->len = tun_encap_info_len; 152 tun_encap_info = mpls_lwtunnel_encap(newts); 153 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS, 154 &tun_encap_info->labels, tun_encap_info->label); 155 if (ret) 156 goto errout; 157 newts->type = LWTUNNEL_ENCAP_MPLS; 158 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; 159 160 *ts = newts; 161 162 return 0; 163 164 errout: 165 kfree(newts); 166 *ts = NULL; 167 168 return ret; 169 } 170 171 static int mpls_fill_encap_info(struct sk_buff *skb, 172 struct lwtunnel_state *lwtstate) 173 { 174 struct mpls_iptunnel_encap *tun_encap_info; 175 176 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 177 178 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels, 179 tun_encap_info->label)) 180 goto nla_put_failure; 181 182 return 0; 183 184 nla_put_failure: 185 return -EMSGSIZE; 186 } 187 188 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate) 189 { 190 struct mpls_iptunnel_encap *tun_encap_info; 191 192 tun_encap_info = mpls_lwtunnel_encap(lwtstate); 193 194 return nla_total_size(tun_encap_info->labels * 4); 195 } 196 197 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 198 { 199 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a); 200 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b); 201 int l; 202 203 if (a_hdr->labels != b_hdr->labels) 204 return 1; 205 206 for (l = 0; l < MAX_NEW_LABELS; l++) 207 if (a_hdr->label[l] != b_hdr->label[l]) 208 return 1; 209 return 0; 210 } 211 212 static const struct lwtunnel_encap_ops mpls_iptun_ops = { 213 .build_state = mpls_build_state, 214 .output = mpls_output, 215 .fill_encap = mpls_fill_encap_info, 216 .get_encap_size = mpls_encap_nlsize, 217 .cmp_encap = mpls_encap_cmp, 218 }; 219 220 static int __init mpls_iptunnel_init(void) 221 { 222 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 223 } 224 module_init(mpls_iptunnel_init); 225 226 static void __exit mpls_iptunnel_exit(void) 227 { 228 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); 229 } 230 module_exit(mpls_iptunnel_exit); 231 232 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); 233 MODULE_LICENSE("GPL v2"); 234