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/pfil.h> 44 #include <net/vnet.h> 45 46 #include <netinet/in.h> 47 #include <netinet/in_kdtrace.h> 48 #include <netinet/in_var.h> 49 #include <netinet/ip_var.h> 50 #include <netinet/ip6.h> 51 #include <netinet/icmp6.h> 52 #include <netinet6/in6_var.h> 53 #include <netinet6/in6_fib.h> 54 #include <netinet6/ip6_var.h> 55 #include <netinet6/nd6.h> 56 57 static int 58 ip6_findroute(struct nhop6_basic *pnh, const struct sockaddr_in6 *dst, 59 struct mbuf *m) 60 { 61 62 if (fib6_lookup_nh_basic(M_GETFIB(m), &dst->sin6_addr, 63 dst->sin6_scope_id, 0, dst->sin6_flowinfo, pnh) != 0) { 64 IP6STAT_INC(ip6s_noroute); 65 IP6STAT_INC(ip6s_cantforward); 66 icmp6_error(m, ICMP6_DST_UNREACH, 67 ICMP6_DST_UNREACH_NOROUTE, 0); 68 return (EHOSTUNREACH); 69 } 70 if (pnh->nh_flags & NHF_BLACKHOLE) { 71 IP6STAT_INC(ip6s_cantforward); 72 m_freem(m); 73 return (EHOSTUNREACH); 74 } 75 76 if (pnh->nh_flags & NHF_REJECT) { 77 IP6STAT_INC(ip6s_cantforward); 78 icmp6_error(m, ICMP6_DST_UNREACH, 79 ICMP6_DST_UNREACH_REJECT, 0); 80 return (EHOSTUNREACH); 81 } 82 return (0); 83 } 84 85 struct mbuf* 86 ip6_tryforward(struct mbuf *m) 87 { 88 struct sockaddr_in6 dst; 89 struct nhop6_basic nh; 90 struct m_tag *fwd_tag; 91 struct ip6_hdr *ip6; 92 struct ifnet *rcvif; 93 uint32_t plen; 94 int error; 95 96 /* 97 * Fallback conditions to ip6_input for slow path processing. 98 */ 99 ip6 = mtod(m, struct ip6_hdr *); 100 if (ip6->ip6_nxt == IPPROTO_HOPOPTS || 101 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 102 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst) || 103 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src) || 104 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) || 105 in6_localip(&ip6->ip6_dst)) 106 return (m); 107 /* 108 * Check that the amount of data in the buffers 109 * is as at least much as the IPv6 header would have us expect. 110 * Trim mbufs if longer than we expect. 111 * Drop packet if shorter than we expect. 112 */ 113 rcvif = m->m_pkthdr.rcvif; 114 plen = ntohs(ip6->ip6_plen); 115 if (plen == 0) { 116 /* 117 * Jumbograms must have hop-by-hop header and go via 118 * slow path. 119 */ 120 IP6STAT_INC(ip6s_badoptions); 121 goto dropin; 122 } 123 if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) { 124 IP6STAT_INC(ip6s_tooshort); 125 in6_ifstat_inc(rcvif, ifs6_in_truncated); 126 goto dropin; 127 } 128 if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) { 129 if (m->m_len == m->m_pkthdr.len) { 130 m->m_len = sizeof(struct ip6_hdr) + plen; 131 m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen; 132 } else 133 m_adj(m, sizeof(struct ip6_hdr) + plen - 134 m->m_pkthdr.len); 135 } 136 137 /* 138 * Hop limit. 139 */ 140 #ifdef IPSTEALTH 141 if (!V_ip6stealth) 142 #endif 143 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 144 icmp6_error(m, ICMP6_TIME_EXCEEDED, 145 ICMP6_TIME_EXCEED_TRANSIT, 0); 146 m = NULL; 147 goto dropin; 148 } 149 150 bzero(&dst, sizeof(dst)); 151 dst.sin6_family = AF_INET6; 152 dst.sin6_len = sizeof(dst); 153 dst.sin6_addr = ip6->ip6_dst; 154 155 /* 156 * Incoming packet firewall processing. 157 */ 158 if (!PFIL_HOOKED(&V_inet6_pfil_hook)) 159 goto passin; 160 if (pfil_run_hooks(&V_inet6_pfil_hook, &m, rcvif, PFIL_IN, 161 NULL) != 0 || m == NULL) 162 goto dropin; 163 /* 164 * If packet filter sets the M_FASTFWD_OURS flag, this means 165 * that new destination or next hop is our local address. 166 * So, we can just go back to ip6_input. 167 * XXX: should we decrement ip6_hlim in such case? 168 * 169 * Also it can forward packet to another destination, e.g. 170 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 171 */ 172 if (m->m_flags & M_FASTFWD_OURS) 173 return (m); 174 175 ip6 = mtod(m, struct ip6_hdr *); 176 if ((m->m_flags & M_IP6_NEXTHOP) && 177 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) { 178 /* 179 * Now we will find route to forwarded by pfil destination. 180 */ 181 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 182 m->m_flags &= ~M_IP6_NEXTHOP; 183 m_tag_delete(m, fwd_tag); 184 } else { 185 /* Update dst since pfil could change it */ 186 dst.sin6_addr = ip6->ip6_dst; 187 } 188 passin: 189 /* 190 * Find route to destination. 191 */ 192 if (ip6_findroute(&nh, &dst, m) != 0) { 193 m = NULL; 194 in6_ifstat_inc(rcvif, ifs6_in_noroute); 195 goto dropin; 196 } 197 198 /* 199 * Outgoing packet firewall processing. 200 */ 201 if (!PFIL_HOOKED(&V_inet6_pfil_hook)) 202 goto passout; 203 if (pfil_run_hooks(&V_inet6_pfil_hook, &m, nh.nh_ifp, PFIL_OUT, 204 NULL) != 0 || m == NULL) 205 goto dropout; 206 207 /* 208 * We used slow path processing for packets with scoped addresses. 209 * So, scope checks aren't needed here. 210 */ 211 if (m->m_pkthdr.len > nh.nh_mtu) { 212 in6_ifstat_inc(nh.nh_ifp, ifs6_in_toobig); 213 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh.nh_mtu); 214 m = NULL; 215 goto dropout; 216 } 217 218 /* 219 * If packet filter sets the M_FASTFWD_OURS flag, this means 220 * that new destination or next hop is our local address. 221 * So, we can just go back to ip6_input. 222 * 223 * Also it can forward packet to another destination, e.g. 224 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 225 */ 226 if (m->m_flags & M_FASTFWD_OURS) { 227 /* 228 * XXX: we did one hop and should decrement hop limit. But 229 * now we are the destination and just don't pay attention. 230 */ 231 return (m); 232 } 233 /* 234 * Again. A packet filter could change the destination address. 235 */ 236 ip6 = mtod(m, struct ip6_hdr *); 237 if (m->m_flags & M_IP6_NEXTHOP) 238 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 239 else 240 fwd_tag = NULL; 241 242 if (fwd_tag != NULL || 243 !IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &ip6->ip6_dst)) { 244 if (fwd_tag != NULL) { 245 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 246 m->m_flags &= ~M_IP6_NEXTHOP; 247 m_tag_delete(m, fwd_tag); 248 } else 249 dst.sin6_addr = ip6->ip6_dst; 250 /* 251 * Redo route lookup with new destination address 252 */ 253 if (ip6_findroute(&nh, &dst, m) != 0) { 254 m = NULL; 255 goto dropout; 256 } 257 } 258 passout: 259 #ifdef IPSTEALTH 260 if (!V_ip6stealth) 261 #endif 262 { 263 ip6->ip6_hlim -= IPV6_HLIMDEC; 264 } 265 266 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 267 IP_PROBE(send, NULL, NULL, ip6, nh.nh_ifp, NULL, ip6); 268 269 /* 270 * XXX: we need to use destination address with embedded scope 271 * zone id, because LLTABLE uses such form of addresses for lookup. 272 */ 273 dst.sin6_addr = nh.nh_addr; 274 if (IN6_IS_SCOPE_LINKLOCAL(&dst.sin6_addr)) 275 dst.sin6_addr.s6_addr16[1] = htons(nh.nh_ifp->if_index & 0xffff); 276 277 error = (*nh.nh_ifp->if_output)(nh.nh_ifp, m, 278 (struct sockaddr *)&dst, NULL); 279 if (error != 0) { 280 in6_ifstat_inc(nh.nh_ifp, ifs6_out_discard); 281 IP6STAT_INC(ip6s_cantforward); 282 } else { 283 in6_ifstat_inc(nh.nh_ifp, ifs6_out_forward); 284 IP6STAT_INC(ip6s_forward); 285 } 286 return (NULL); 287 dropin: 288 in6_ifstat_inc(rcvif, ifs6_in_discard); 289 goto drop; 290 dropout: 291 in6_ifstat_inc(nh.nh_ifp, ifs6_out_discard); 292 drop: 293 if (m != NULL) 294 m_freem(m); 295 return (NULL); 296 } 297 298