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 "opt_inet6.h" 28 #include "opt_ipstealth.h" 29 #include "opt_sctp.h" 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/mbuf.h> 34 #include <sys/socket.h> 35 #include <sys/kernel.h> 36 #include <sys/sysctl.h> 37 38 #include <net/if.h> 39 #include <net/if_var.h> 40 #include <net/if_private.h> 41 #include <net/route.h> 42 #include <net/route/nhop.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 #if defined(SCTP) || defined(SCTP_SUPPORT) 58 #include <netinet/sctp_crc32.h> 59 #endif 60 61 static int 62 ip6_findroute(struct nhop_object **pnh, const struct sockaddr_in6 *dst, 63 struct mbuf *m) 64 { 65 struct nhop_object *nh; 66 67 nh = fib6_lookup(M_GETFIB(m), &dst->sin6_addr, 68 dst->sin6_scope_id, NHR_NONE, m->m_pkthdr.flowid); 69 if (nh == NULL) { 70 IP6STAT_INC(ip6s_noroute); 71 IP6STAT_INC(ip6s_cantforward); 72 icmp6_error(m, ICMP6_DST_UNREACH, 73 ICMP6_DST_UNREACH_NOROUTE, 0); 74 return (EHOSTUNREACH); 75 } 76 if (nh->nh_flags & NHF_BLACKHOLE) { 77 IP6STAT_INC(ip6s_cantforward); 78 m_freem(m); 79 return (EHOSTUNREACH); 80 } 81 82 if (nh->nh_flags & NHF_REJECT) { 83 IP6STAT_INC(ip6s_cantforward); 84 icmp6_error(m, ICMP6_DST_UNREACH, 85 ICMP6_DST_UNREACH_REJECT, 0); 86 return (EHOSTUNREACH); 87 } 88 89 *pnh = nh; 90 91 return (0); 92 } 93 94 struct mbuf* 95 ip6_tryforward(struct mbuf *m) 96 { 97 struct sockaddr_in6 dst; 98 struct nhop_object *nh; 99 struct m_tag *fwd_tag; 100 struct ip6_hdr *ip6; 101 struct ifnet *rcvif; 102 uint32_t plen; 103 int error; 104 105 /* 106 * Fallback conditions to ip6_input for slow path processing. 107 */ 108 ip6 = mtod(m, struct ip6_hdr *); 109 if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 || 110 ip6->ip6_nxt == IPPROTO_HOPOPTS || 111 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 112 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst) || 113 IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src) || 114 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst) || 115 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) || 116 in6_localip(&ip6->ip6_dst)) 117 return (m); 118 /* 119 * Check that the amount of data in the buffers 120 * is as at least much as the IPv6 header would have us expect. 121 * Trim mbufs if longer than we expect. 122 * Drop packet if shorter than we expect. 123 */ 124 rcvif = m->m_pkthdr.rcvif; 125 plen = ntohs(ip6->ip6_plen); 126 if (plen == 0) { 127 /* 128 * Jumbograms must have hop-by-hop header and go via 129 * slow path. 130 */ 131 IP6STAT_INC(ip6s_badoptions); 132 goto dropin; 133 } 134 if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) { 135 IP6STAT_INC(ip6s_tooshort); 136 in6_ifstat_inc(rcvif, ifs6_in_truncated); 137 goto dropin; 138 } 139 if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) { 140 if (m->m_len == m->m_pkthdr.len) { 141 m->m_len = sizeof(struct ip6_hdr) + plen; 142 m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen; 143 } else 144 m_adj(m, sizeof(struct ip6_hdr) + plen - 145 m->m_pkthdr.len); 146 } 147 148 /* 149 * Hop limit. 150 */ 151 #ifdef IPSTEALTH 152 if (!V_ip6stealth) 153 #endif 154 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 155 icmp6_error(m, ICMP6_TIME_EXCEEDED, 156 ICMP6_TIME_EXCEED_TRANSIT, 0); 157 m = NULL; 158 goto dropin; 159 } 160 161 bzero(&dst, sizeof(dst)); 162 dst.sin6_family = AF_INET6; 163 dst.sin6_len = sizeof(dst); 164 dst.sin6_addr = ip6->ip6_dst; 165 166 /* 167 * Incoming packet firewall processing. 168 */ 169 if (!PFIL_HOOKED_IN(V_inet6_pfil_head)) 170 goto passin; 171 if (pfil_mbuf_in(V_inet6_pfil_head, &m, rcvif, NULL) != 172 PFIL_PASS) 173 goto dropin; 174 /* 175 * If packet filter sets the M_FASTFWD_OURS flag, this means 176 * that new destination or next hop is our local address. 177 * So, we can just go back to ip6_input. 178 * XXX: should we decrement ip6_hlim in such case? 179 * 180 * Also it can forward packet to another destination, e.g. 181 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 182 */ 183 if (m->m_flags & M_FASTFWD_OURS) 184 return (m); 185 186 ip6 = mtod(m, struct ip6_hdr *); 187 if ((m->m_flags & M_IP6_NEXTHOP) && 188 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) { 189 /* 190 * Now we will find route to forwarded by pfil destination. 191 */ 192 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 193 m->m_flags &= ~M_IP6_NEXTHOP; 194 m_tag_delete(m, fwd_tag); 195 } else { 196 /* Update dst since pfil could change it */ 197 dst.sin6_addr = ip6->ip6_dst; 198 } 199 passin: 200 /* 201 * Find route to destination. 202 */ 203 if (ip6_findroute(&nh, &dst, m) != 0) { 204 m = NULL; 205 in6_ifstat_inc(rcvif, ifs6_in_noroute); 206 goto dropin; 207 } 208 if (!PFIL_HOOKED_OUT(V_inet6_pfil_head)) { 209 if (m->m_pkthdr.len > nh->nh_mtu) { 210 in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig); 211 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu); 212 m = NULL; 213 goto dropout; 214 } 215 goto passout; 216 } 217 218 /* 219 * Outgoing packet firewall processing. 220 */ 221 if (pfil_mbuf_out(V_inet6_pfil_head, &m, nh->nh_ifp, 222 NULL) != PFIL_PASS) 223 goto dropout; 224 225 /* 226 * We used slow path processing for packets with scoped addresses. 227 * So, scope checks aren't needed here. 228 */ 229 if (m->m_pkthdr.len > nh->nh_mtu) { 230 in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig); 231 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu); 232 m = NULL; 233 goto dropout; 234 } 235 236 /* 237 * If packet filter sets the M_FASTFWD_OURS flag, this means 238 * that new destination or next hop is our local address. 239 * So, we can just go back to ip6_input. 240 * 241 * Also it can forward packet to another destination, e.g. 242 * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf. 243 */ 244 if (m->m_flags & M_FASTFWD_OURS) { 245 /* 246 * XXX: we did one hop and should decrement hop limit. But 247 * now we are the destination and just don't pay attention. 248 */ 249 return (m); 250 } 251 /* 252 * Again. A packet filter could change the destination address. 253 */ 254 ip6 = mtod(m, struct ip6_hdr *); 255 if (m->m_flags & M_IP6_NEXTHOP) 256 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 257 else 258 fwd_tag = NULL; 259 260 if (fwd_tag != NULL || 261 !IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &ip6->ip6_dst)) { 262 if (fwd_tag != NULL) { 263 bcopy((fwd_tag + 1), &dst, sizeof(dst)); 264 m->m_flags &= ~M_IP6_NEXTHOP; 265 m_tag_delete(m, fwd_tag); 266 } else 267 dst.sin6_addr = ip6->ip6_dst; 268 /* 269 * Redo route lookup with new destination address 270 */ 271 if (ip6_findroute(&nh, &dst, m) != 0) { 272 m = NULL; 273 goto dropout; 274 } 275 } 276 passout: 277 #ifdef IPSTEALTH 278 if (!V_ip6stealth) 279 #endif 280 { 281 ip6->ip6_hlim -= IPV6_HLIMDEC; 282 } 283 284 /* 285 * If TCP/UDP header still needs a valid checksum and interface will not 286 * calculate it for us, do it here. 287 */ 288 if (__predict_false(m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6 & 289 ~nh->nh_ifp->if_hwassist)) { 290 int offset = ip6_lasthdr(m, 0, IPPROTO_IPV6, NULL); 291 292 if (offset < sizeof(struct ip6_hdr) || offset > m->m_pkthdr.len) 293 goto drop; 294 in6_delayed_cksum(m, m->m_pkthdr.len - offset, offset); 295 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6; 296 } 297 #if defined(SCTP) || defined(SCTP_SUPPORT) 298 if (__predict_false(m->m_pkthdr.csum_flags & CSUM_IP6_SCTP & 299 ~nh->nh_ifp->if_hwassist)) { 300 int offset = ip6_lasthdr(m, 0, IPPROTO_IPV6, NULL); 301 302 sctp_delayed_cksum(m, offset); 303 m->m_pkthdr.csum_flags &= ~CSUM_IP6_SCTP; 304 } 305 #endif 306 307 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 308 IP_PROBE(send, NULL, NULL, ip6, nh->nh_ifp, NULL, ip6); 309 310 if (nh->nh_flags & NHF_GATEWAY) 311 dst.sin6_addr = nh->gw6_sa.sin6_addr; 312 error = (*nh->nh_ifp->if_output)(nh->nh_ifp, m, 313 (struct sockaddr *)&dst, NULL); 314 if (error != 0) { 315 in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard); 316 IP6STAT_INC(ip6s_cantforward); 317 } else { 318 in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward); 319 IP6STAT_INC(ip6s_forward); 320 } 321 return (NULL); 322 dropin: 323 in6_ifstat_inc(rcvif, ifs6_in_discard); 324 goto drop; 325 dropout: 326 in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard); 327 drop: 328 if (m != NULL) 329 m_freem(m); 330 return (NULL); 331 } 332