1 /*- 2 * Copyright (c) 2014-2016 Andrey V. Elsukov <ae@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_inet6.h" 31 #include "opt_ipstealth.h" 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/mbuf.h> 36 #include <sys/socket.h> 37 #include <sys/kernel.h> 38 #include <sys/sysctl.h> 39 40 #include <net/if.h> 41 #include <net/if_var.h> 42 #include <net/route.h> 43 #include <net/route/nhop.h> 44 #include <net/pfil.h> 45 #include <net/vnet.h> 46 47 #include <netinet/in.h> 48 #include <netinet/in_kdtrace.h> 49 #include <netinet/in_var.h> 50 #include <netinet/ip_var.h> 51 #include <netinet/ip6.h> 52 #include <netinet/icmp6.h> 53 #include <netinet6/in6_var.h> 54 #include <netinet6/in6_fib.h> 55 #include <netinet6/ip6_var.h> 56 #include <netinet6/nd6.h> 57 58 static int 59 ip6_findroute(struct nhop_object **pnh, const struct sockaddr_in6 *dst, 60 struct mbuf *m) 61 { 62 struct nhop_object *nh; 63 64 nh = fib6_lookup(M_GETFIB(m), &dst->sin6_addr, 65 dst->sin6_scope_id, NHR_NONE, m->m_pkthdr.flowid); 66 if (nh == NULL) { 67 IP6STAT_INC(ip6s_noroute); 68 IP6STAT_INC(ip6s_cantforward); 69 icmp6_error(m, ICMP6_DST_UNREACH, 70 ICMP6_DST_UNREACH_NOROUTE, 0); 71 return (EHOSTUNREACH); 72 } 73 if (nh->nh_flags & NHF_BLACKHOLE) { 74 IP6STAT_INC(ip6s_cantforward); 75 m_freem(m); 76 return (EHOSTUNREACH); 77 } 78 79 if (nh->nh_flags & NHF_REJECT) { 80 IP6STAT_INC(ip6s_cantforward); 81 icmp6_error(m, ICMP6_DST_UNREACH, 82 ICMP6_DST_UNREACH_REJECT, 0); 83 return (EHOSTUNREACH); 84 } 85 86 *pnh = nh; 87 88 return (0); 89 } 90 91 struct mbuf* 92 ip6_tryforward(struct mbuf *m) 93 { 94 struct sockaddr_in6 dst; 95 struct nhop_object *nh; 96 struct m_tag *fwd_tag; 97 struct ip6_hdr *ip6; 98 struct ifnet *rcvif; 99 uint32_t plen; 100 int error; 101 102 /* 103 * Fallback conditions to ip6_input for slow path processing. 104 */ 105 ip6 = mtod(m, struct ip6_hdr *); 106 if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 || 107 ip6->ip6_nxt == IPPROTO_HOPOPTS || 108 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 109 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst) || 110 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src) || 111 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) || 112 in6_localip(&ip6->ip6_dst)) 113 return (m); 114 /* 115 * Check that the amount of data in the buffers 116 * is as at least much as the IPv6 header would have us expect. 117 * Trim mbufs if longer than we expect. 118 * Drop packet if shorter than we expect. 119 */ 120 rcvif = m->m_pkthdr.rcvif; 121 plen = ntohs(ip6->ip6_plen); 122 if (plen == 0) { 123 /* 124 * Jumbograms must have hop-by-hop header and go via 125 * slow path. 126 */ 127 IP6STAT_INC(ip6s_badoptions); 128 goto dropin; 129 } 130 if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) { 131 IP6STAT_INC(ip6s_tooshort); 132 in6_ifstat_inc(rcvif, ifs6_in_truncated); 133 goto dropin; 134 } 135 if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) { 136 if (m->m_len == m->m_pkthdr.len) { 137 m->m_len = sizeof(struct ip6_hdr) + plen; 138 m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen; 139 } else 140 m_adj(m, sizeof(struct ip6_hdr) + plen - 141 m->m_pkthdr.len); 142 } 143 144 /* 145 * Hop limit. 146 */ 147 #ifdef IPSTEALTH 148 if (!V_ip6stealth) 149 #endif 150 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 151 icmp6_error(m, ICMP6_TIME_EXCEEDED, 152 ICMP6_TIME_EXCEED_TRANSIT, 0); 153 m = NULL; 154 goto dropin; 155 } 156 157 bzero(&dst, sizeof(dst)); 158 dst.sin6_family = AF_INET6; 159 dst.sin6_len = sizeof(dst); 160 dst.sin6_addr = ip6->ip6_dst; 161 162 /* 163 * Incoming packet firewall processing. 164 */ 165 if (!PFIL_HOOKED_IN(V_inet6_pfil_head)) 166 goto passin; 167 if (pfil_mbuf_in(V_inet6_pfil_head, &m, rcvif, NULL) != 168 PFIL_PASS) 169 goto dropin; 170 /* 171 * If packet filter sets the M_FASTFWD_OURS flag, this means 172 * that new destination or next hop is our local address. 173 * So, we can just go back to ip6_input. 174 * XXX: should we decrement ip6_hlim in such case? 175 * 176 * Also it can forward packet to another destination, e.g. 177 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 178 */ 179 if (m->m_flags & M_FASTFWD_OURS) 180 return (m); 181 182 ip6 = mtod(m, struct ip6_hdr *); 183 if ((m->m_flags & M_IP6_NEXTHOP) && 184 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) { 185 /* 186 * Now we will find route to forwarded by pfil destination. 187 */ 188 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 189 m->m_flags &= ~M_IP6_NEXTHOP; 190 m_tag_delete(m, fwd_tag); 191 } else { 192 /* Update dst since pfil could change it */ 193 dst.sin6_addr = ip6->ip6_dst; 194 } 195 passin: 196 /* 197 * Find route to destination. 198 */ 199 if (ip6_findroute(&nh, &dst, m) != 0) { 200 m = NULL; 201 in6_ifstat_inc(rcvif, ifs6_in_noroute); 202 goto dropin; 203 } 204 if (!PFIL_HOOKED_OUT(V_inet6_pfil_head)) { 205 if (m->m_pkthdr.len > nh->nh_mtu) { 206 in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig); 207 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu); 208 m = NULL; 209 goto dropout; 210 } 211 goto passout; 212 } 213 214 /* 215 * Outgoing packet firewall processing. 216 */ 217 if (pfil_mbuf_out(V_inet6_pfil_head, &m, nh->nh_ifp, 218 NULL) != PFIL_PASS) 219 goto dropout; 220 221 /* 222 * We used slow path processing for packets with scoped addresses. 223 * So, scope checks aren't needed here. 224 */ 225 if (m->m_pkthdr.len > nh->nh_mtu) { 226 in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig); 227 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu); 228 m = NULL; 229 goto dropout; 230 } 231 232 /* 233 * If packet filter sets the M_FASTFWD_OURS flag, this means 234 * that new destination or next hop is our local address. 235 * So, we can just go back to ip6_input. 236 * 237 * Also it can forward packet to another destination, e.g. 238 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 239 */ 240 if (m->m_flags & M_FASTFWD_OURS) { 241 /* 242 * XXX: we did one hop and should decrement hop limit. But 243 * now we are the destination and just don't pay attention. 244 */ 245 return (m); 246 } 247 /* 248 * Again. A packet filter could change the destination address. 249 */ 250 ip6 = mtod(m, struct ip6_hdr *); 251 if (m->m_flags & M_IP6_NEXTHOP) 252 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 253 else 254 fwd_tag = NULL; 255 256 if (fwd_tag != NULL || 257 !IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &ip6->ip6_dst)) { 258 if (fwd_tag != NULL) { 259 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 260 m->m_flags &= ~M_IP6_NEXTHOP; 261 m_tag_delete(m, fwd_tag); 262 } else 263 dst.sin6_addr = ip6->ip6_dst; 264 /* 265 * Redo route lookup with new destination address 266 */ 267 if (ip6_findroute(&nh, &dst, m) != 0) { 268 m = NULL; 269 goto dropout; 270 } 271 } 272 passout: 273 #ifdef IPSTEALTH 274 if (!V_ip6stealth) 275 #endif 276 { 277 ip6->ip6_hlim -= IPV6_HLIMDEC; 278 } 279 280 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 281 IP_PROBE(send, NULL, NULL, ip6, nh->nh_ifp, NULL, ip6); 282 283 if (nh->nh_flags & NHF_GATEWAY) 284 dst.sin6_addr = nh->gw6_sa.sin6_addr; 285 error = (*nh->nh_ifp->if_output)(nh->nh_ifp, m, 286 (struct sockaddr *)&dst, NULL); 287 if (error != 0) { 288 in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard); 289 IP6STAT_INC(ip6s_cantforward); 290 } else { 291 in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward); 292 IP6STAT_INC(ip6s_forward); 293 } 294 return (NULL); 295 dropin: 296 in6_ifstat_inc(rcvif, ifs6_in_discard); 297 goto drop; 298 dropout: 299 in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard); 300 drop: 301 if (m != NULL) 302 m_freem(m); 303 return (NULL); 304 } 305