/* $OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt Exp $ */ /*- * The authors of this code are John Ioannidis (ji@tla.org), * Angelos D. Keromytis (kermit@csd.uch.gr) and * Niels Provos (provos@physnet.uni-hamburg.de). * * This code was written by John Ioannidis for BSD/OS in Athens, Greece, * in November 1995. * * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996, * by Angelos D. Keromytis. * * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis * and Niels Provos. * * Additional features in 1999 by Angelos D. Keromytis. * * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis, * Angelos D. Keromytis and Niels Provos. * Copyright (c) 2001, Angelos D. Keromytis. * Copyright (c) 2016 Andrey V. Elsukov * * Permission to use, copy, and modify this software with or without fee * is hereby granted, provided that this entire notice is included in * all copies of any software which is or includes a copy or * modification of this software. * You may use this code under the GNU public license if you so wish. Please * contribute changes back to the authors under this freer than GPL license * so that we may further the use of strong encryption without limitations to * all. * * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR * PURPOSE. */ /* * IPsec input processing. */ #include #include "opt_inet.h" #include "opt_inet6.h" #include "opt_ipsec.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #endif #include #ifdef INET6 #include #endif #include #ifdef INET6 #include #endif #include #include #include #include #include #include #include #include #include #include #include #define IPSEC_ISTAT(proto, name) do { \ if ((proto) == IPPROTO_ESP) \ ESPSTAT_INC(esps_##name); \ else if ((proto) == IPPROTO_AH) \ AHSTAT_INC(ahs_##name); \ else \ IPCOMPSTAT_INC(ipcomps_##name); \ } while (0) /* * ipsec_common_input gets called when an IPsec-protected packet * is received by IPv4 or IPv6. Its job is to find the right SA * and call the appropriate transform. The transform callback * takes care of further processing (like ingress filtering). */ static int ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto) { IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]); union sockaddr_union dst_address; struct secasvar *sav; uint32_t spi; int error; IPSEC_ISTAT(sproto, input); IPSEC_ASSERT(m != NULL, ("null packet")); IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || sproto == IPPROTO_IPCOMP, ("unexpected security protocol %u", sproto)); if ((sproto == IPPROTO_ESP && !V_esp_enable) || (sproto == IPPROTO_AH && !V_ah_enable) || (sproto == IPPROTO_IPCOMP && !V_ipcomp_enable)) { m_freem(m); IPSEC_ISTAT(sproto, pdrops); return EOPNOTSUPP; } if (m->m_pkthdr.len - skip < 2 * sizeof (u_int32_t)) { m_freem(m); IPSEC_ISTAT(sproto, hdrops); DPRINTF(("%s: packet too small\n", __func__)); return EINVAL; } /* Retrieve the SPI from the relevant IPsec header */ if (sproto == IPPROTO_ESP) m_copydata(m, skip, sizeof(u_int32_t), (caddr_t) &spi); else if (sproto == IPPROTO_AH) m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t), (caddr_t) &spi); else if (sproto == IPPROTO_IPCOMP) { u_int16_t cpi; m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t), (caddr_t) &cpi); spi = ntohl(htons(cpi)); } /* * Find the SA and (indirectly) call the appropriate * kernel crypto routine. The resulting mbuf chain is a valid * IP packet ready to go through input processing. */ bzero(&dst_address, sizeof (dst_address)); dst_address.sa.sa_family = af; switch (af) { #ifdef INET case AF_INET: dst_address.sin.sin_len = sizeof(struct sockaddr_in); m_copydata(m, offsetof(struct ip, ip_dst), sizeof(struct in_addr), (caddr_t) &dst_address.sin.sin_addr); break; #endif /* INET */ #ifdef INET6 case AF_INET6: dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6); m_copydata(m, offsetof(struct ip6_hdr, ip6_dst), sizeof(struct in6_addr), (caddr_t) &dst_address.sin6.sin6_addr); /* We keep addresses in SADB without embedded scope id */ if (IN6_IS_SCOPE_LINKLOCAL(&dst_address.sin6.sin6_addr)) { /* XXX: sa6_recoverscope() */ dst_address.sin6.sin6_scope_id = ntohs(dst_address.sin6.sin6_addr.s6_addr16[1]); dst_address.sin6.sin6_addr.s6_addr16[1] = 0; } break; #endif /* INET6 */ default: DPRINTF(("%s: unsupported protocol family %u\n", __func__, af)); m_freem(m); IPSEC_ISTAT(sproto, nopf); return EPFNOSUPPORT; } /* NB: only pass dst since key_allocsa follows RFC2401 */ sav = key_allocsa(&dst_address, sproto, spi); if (sav == NULL) { DPRINTF(("%s: no key association found for SA %s/%08lx/%u\n", __func__, ipsec_address(&dst_address, buf, sizeof(buf)), (u_long) ntohl(spi), sproto)); IPSEC_ISTAT(sproto, notdb); m_freem(m); return ENOENT; } if (sav->tdb_xform == NULL) { DPRINTF(("%s: attempted to use uninitialized SA %s/%08lx/%u\n", __func__, ipsec_address(&dst_address, buf, sizeof(buf)), (u_long) ntohl(spi), sproto)); IPSEC_ISTAT(sproto, noxform); key_freesav(&sav); m_freem(m); return ENXIO; } /* * Call appropriate transform and return -- callback takes care of * everything else. */ error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); return (error); } #ifdef INET /* * IPSEC_INPUT() method implementation for IPv4. * 0 - Permitted by inbound security policy for further processing. * EACCES - Forbidden by inbound security policy. * EINPROGRESS - consumed by IPsec. */ int ipsec4_input(struct mbuf *m, int offset, int proto) { switch (proto) { case IPPROTO_AH: case IPPROTO_ESP: case IPPROTO_IPCOMP: /* Do inbound IPsec processing for AH/ESP/IPCOMP */ ipsec_common_input(m, offset, offsetof(struct ip, ip_p), AF_INET, proto); return (EINPROGRESS); /* mbuf consumed by IPsec */ default: /* * Protocols with further headers get their IPsec treatment * within the protocol specific processing. */ switch (proto) { case IPPROTO_ICMP: case IPPROTO_IGMP: case IPPROTO_IPV4: case IPPROTO_IPV6: case IPPROTO_RSVP: case IPPROTO_GRE: case IPPROTO_MOBILE: case IPPROTO_ETHERIP: case IPPROTO_PIM: case IPPROTO_SCTP: break; default: return (0); } }; /* * Enforce IPsec policy checking if we are seeing last header. */ if (ipsec4_in_reject(m, NULL) != 0) { /* Forbidden by inbound security policy */ m_freem(m); return (EACCES); } return (0); } int ipsec4_ctlinput(ipsec_ctlinput_param_t param) { struct icmp *icp = param.icmp; struct ip *ip = &icp->icmp_ip; struct sockaddr_in icmpsrc = { .sin_len = sizeof(struct sockaddr_in), .sin_family = AF_INET, .sin_addr = ip->ip_dst, }; struct in_conninfo inc; struct secasvar *sav; uint32_t pmtu, spi; uint32_t max_pmtu; uint8_t proto; pmtu = ntohs(icp->icmp_nextmtu); if (pmtu < V_ip4_ipsec_min_pmtu) return (EINVAL); proto = ip->ip_p; if (proto != IPPROTO_ESP && proto != IPPROTO_AH && proto != IPPROTO_IPCOMP) return (EINVAL); memcpy(&spi, (caddr_t)ip + (ip->ip_hl << 2), sizeof(spi)); sav = key_allocsa((union sockaddr_union *)&icmpsrc, proto, spi); if (sav == NULL) return (ENOENT); key_freesav(&sav); memset(&inc, 0, sizeof(inc)); inc.inc_faddr = ip->ip_dst; /* Update pmtu only if its smaller than the current one. */ max_pmtu = tcp_hc_getmtu(&inc); if (max_pmtu == 0) max_pmtu = tcp_maxmtu(&inc, NULL); if (pmtu < max_pmtu) tcp_hc_updatemtu(&inc, pmtu); return (0); } /* * IPsec input callback for INET protocols. * This routine is called as the transform callback. * Takes care of filtering and other sanity checks on * the processed packet. */ int ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, int protoff) { IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]); struct epoch_tracker et; struct ipsec_ctx_data ctx; struct xform_history *xh; struct secasindex *saidx; struct m_tag *mtag; struct ip *ip; int error, prot, af, sproto, isr_prot; IPSEC_ASSERT(sav != NULL, ("null SA")); IPSEC_ASSERT(sav->sah != NULL, ("null SAH")); saidx = &sav->sah->saidx; af = saidx->dst.sa.sa_family; IPSEC_ASSERT(af == AF_INET, ("unexpected af %u", af)); sproto = saidx->proto; IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || sproto == IPPROTO_IPCOMP, ("unexpected security protocol %u", sproto)); if (skip != 0) { /* * Fix IPv4 header */ if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { DPRINTF(("%s: processing failed for SA %s/%08lx\n", __func__, ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), (u_long) ntohl(sav->spi))); IPSEC_ISTAT(sproto, hdrops); error = ENOBUFS; goto bad_noepoch; } ip = mtod(m, struct ip *); ip->ip_len = htons(m->m_pkthdr.len); ip->ip_sum = 0; ip->ip_sum = in_cksum(m, ip->ip_hl << 2); } else { ip = mtod(m, struct ip *); } prot = ip->ip_p; /* * Check that we have NAT-T enabled and apply transport mode * decapsulation NAT procedure (RFC3948). * Do this before invoking into the PFIL. */ if (sav->natt != NULL && (prot == IPPROTO_UDP || prot == IPPROTO_TCP)) udp_ipsec_adjust_cksum(m, sav, prot, skip); /* * Needed for ipsec_run_hooks and netisr_queue_src */ NET_EPOCH_ENTER(et); IPSEC_INIT_CTX(&ctx, &m, NULL, sav, AF_INET, IPSEC_ENC_BEFORE); if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0) goto bad; ip = mtod(m, struct ip *); /* update pointer */ /* IP-in-IP encapsulation */ if (prot == IPPROTO_IPIP && saidx->mode != IPSEC_MODE_TRANSPORT) { if (m->m_pkthdr.len - skip < sizeof(struct ip)) { IPSEC_ISTAT(sproto, hdrops); error = EINVAL; goto bad; } /* enc0: strip outer IPv4 header */ m_striphdr(m, 0, ip->ip_hl << 2); } #ifdef INET6 /* IPv6-in-IP encapsulation. */ else if (prot == IPPROTO_IPV6 && saidx->mode != IPSEC_MODE_TRANSPORT) { if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) { IPSEC_ISTAT(sproto, hdrops); error = EINVAL; goto bad; } /* enc0: strip IPv4 header, keep IPv6 header only */ m_striphdr(m, 0, ip->ip_hl << 2); } #endif /* INET6 */ else if (prot != IPPROTO_IPV6 && saidx->mode == IPSEC_MODE_ANY) { /* * When mode is wildcard, inner protocol is IPv6 and * we have no INET6 support - drop this packet a bit later. * In other cases we assume transport mode. Set prot to * correctly choose netisr. */ prot = IPPROTO_IPIP; } /* * Record what we've done to the packet (under what SA it was * processed). */ if (sproto != IPPROTO_IPCOMP) { mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE, sizeof(struct xform_history), M_NOWAIT); if (mtag == NULL) { DPRINTF(("%s: failed to get tag\n", __func__)); IPSEC_ISTAT(sproto, hdrops); error = ENOMEM; goto bad; } xh = (struct xform_history *)(mtag + 1); bcopy(&saidx->dst, &xh->dst, saidx->dst.sa.sa_len); xh->spi = sav->spi; xh->proto = sproto; xh->mode = saidx->mode; m_tag_prepend(m, mtag); } key_sa_recordxfer(sav, m); /* record data transfer */ /* * In transport mode requeue decrypted mbuf back to IPv4 protocol * handler. This is necessary to correctly expose rcvif. */ if (saidx->mode == IPSEC_MODE_TRANSPORT) prot = IPPROTO_IPIP; /* * Re-dispatch via software interrupt. */ switch (prot) { case IPPROTO_IPIP: isr_prot = NETISR_IP; af = AF_INET; break; #ifdef INET6 case IPPROTO_IPV6: isr_prot = NETISR_IPV6; af = AF_INET6; break; #endif default: DPRINTF(("%s: cannot handle inner ip proto %d\n", __func__, prot)); IPSEC_ISTAT(sproto, nopf); error = EPFNOSUPPORT; goto bad; } IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_AFTER); if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0) goto bad; /* Handle virtual tunneling interfaces */ if (saidx->mode == IPSEC_MODE_TUNNEL) error = ipsec_if_input(m, sav, af); if (error == 0) { error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m); if (error) { IPSEC_ISTAT(sproto, qfull); DPRINTF(("%s: queue full; proto %u packet dropped\n", __func__, sproto)); } } NET_EPOCH_EXIT(et); key_freesav(&sav); return (error); bad: NET_EPOCH_EXIT(et); bad_noepoch: key_freesav(&sav); if (m != NULL) m_freem(m); return (error); } #endif /* INET */ #ifdef INET6 static bool ipsec6_lasthdr(int proto) { switch (proto) { case IPPROTO_IPV4: case IPPROTO_IPV6: case IPPROTO_GRE: case IPPROTO_ICMPV6: case IPPROTO_ETHERIP: case IPPROTO_PIM: case IPPROTO_SCTP: return (true); default: return (false); }; } /* * IPSEC_INPUT() method implementation for IPv6. * 0 - Permitted by inbound security policy for further processing. * EACCES - Forbidden by inbound security policy. * EINPROGRESS - consumed by IPsec. */ int ipsec6_input(struct mbuf *m, int offset, int proto) { switch (proto) { case IPPROTO_AH: case IPPROTO_ESP: case IPPROTO_IPCOMP: /* Do inbound IPsec processing for AH/ESP/IPCOMP */ ipsec_common_input(m, offset, offsetof(struct ip6_hdr, ip6_nxt), AF_INET6, proto); return (EINPROGRESS); /* mbuf consumed by IPsec */ default: /* * Protocols with further headers get their IPsec treatment * within the protocol specific processing. */ if (!ipsec6_lasthdr(proto)) return (0); /* FALLTHROUGH */ }; /* * Enforce IPsec policy checking if we are seeing last header. */ if (ipsec6_in_reject(m, NULL) != 0) { /* Forbidden by inbound security policy */ m_freem(m); return (EACCES); } return (0); } int ipsec6_ctlinput(ipsec_ctlinput_param_t param) { return (0); } extern ipproto_input_t *ip6_protox[]; /* * IPsec input callback, called by the transform callback. Takes care of * filtering and other sanity checks on the processed packet. */ int ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, int protoff) { IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]); struct epoch_tracker et; struct ipsec_ctx_data ctx; struct xform_history *xh; struct secasindex *saidx; struct ip6_hdr *ip6; struct m_tag *mtag; int prot, af, sproto; int nxt, isr_prot; int error, nest; uint8_t nxt8; IPSEC_ASSERT(sav != NULL, ("null SA")); IPSEC_ASSERT(sav->sah != NULL, ("null SAH")); saidx = &sav->sah->saidx; af = saidx->dst.sa.sa_family; IPSEC_ASSERT(af == AF_INET6, ("unexpected af %u", af)); sproto = saidx->proto; IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || sproto == IPPROTO_IPCOMP, ("unexpected security protocol %u", sproto)); NET_EPOCH_ENTER(et); /* Fix IPv6 header */ if (m->m_len < sizeof(struct ip6_hdr) && (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { DPRINTF(("%s: processing failed for SA %s/%08lx\n", __func__, ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), (u_long) ntohl(sav->spi))); IPSEC_ISTAT(sproto, hdrops); error = EACCES; goto bad; } IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_BEFORE); if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0) goto bad; ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); /* Save protocol */ m_copydata(m, protoff, 1, &nxt8); prot = nxt8; /* * Check that we have NAT-T enabled and apply transport mode * decapsulation NAT procedure (RFC3948). * Do this before invoking into the PFIL. */ if (sav->natt != NULL && (prot == IPPROTO_UDP || prot == IPPROTO_TCP)) udp_ipsec_adjust_cksum(m, sav, prot, skip); /* IPv6-in-IP encapsulation */ if (prot == IPPROTO_IPV6 && saidx->mode != IPSEC_MODE_TRANSPORT) { if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) { IPSEC_ISTAT(sproto, hdrops); error = EINVAL; goto bad; } /* ip6n will now contain the inner IPv6 header. */ m_striphdr(m, 0, skip); skip = 0; } #ifdef INET /* IP-in-IP encapsulation */ else if (prot == IPPROTO_IPIP && saidx->mode != IPSEC_MODE_TRANSPORT) { if (m->m_pkthdr.len - skip < sizeof(struct ip)) { IPSEC_ISTAT(sproto, hdrops); error = EINVAL; goto bad; } /* ipn will now contain the inner IPv4 header */ m_striphdr(m, 0, skip); skip = 0; } #endif /* INET */ else { prot = IPPROTO_IPV6; /* for correct BPF processing */ } /* * Record what we've done to the packet (under what SA it was * processed). */ if (sproto != IPPROTO_IPCOMP) { mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE, sizeof(struct xform_history), M_NOWAIT); if (mtag == NULL) { DPRINTF(("%s: failed to get tag\n", __func__)); IPSEC_ISTAT(sproto, hdrops); error = ENOMEM; goto bad; } xh = (struct xform_history *)(mtag + 1); bcopy(&saidx->dst, &xh->dst, saidx->dst.sa.sa_len); xh->spi = sav->spi; xh->proto = sproto; xh->mode = saidx->mode; m_tag_prepend(m, mtag); } key_sa_recordxfer(sav, m); #ifdef INET if (prot == IPPROTO_IPIP) af = AF_INET; else #endif af = AF_INET6; IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_AFTER); if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0) goto bad; if (skip == 0) { /* * We stripped outer IPv6 header. * Now we should requeue decrypted packet via netisr. */ switch (prot) { #ifdef INET case IPPROTO_IPIP: isr_prot = NETISR_IP; break; #endif case IPPROTO_IPV6: isr_prot = NETISR_IPV6; break; default: DPRINTF(("%s: cannot handle inner ip proto %d\n", __func__, prot)); IPSEC_ISTAT(sproto, nopf); error = EPFNOSUPPORT; goto bad; } /* Handle virtual tunneling interfaces */ if (saidx->mode == IPSEC_MODE_TUNNEL) error = ipsec_if_input(m, sav, af); if (error == 0) { error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m); if (error) { IPSEC_ISTAT(sproto, qfull); DPRINTF(("%s: queue full; proto %u packet" " dropped\n", __func__, sproto)); } } NET_EPOCH_EXIT(et); key_freesav(&sav); return (error); } /* * See the end of ip6_input for this logic. * IPPROTO_IPV[46] case will be processed just like other ones */ nest = 0; nxt = nxt8; while (nxt != IPPROTO_DONE) { if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) { IP6STAT_INC(ip6s_toomanyhdr); error = EINVAL; goto bad; } /* * Protection against faulty packet - there should be * more sanity checks in header chain processing. */ if (m->m_pkthdr.len < skip) { IP6STAT_INC(ip6s_tooshort); in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated); error = EINVAL; goto bad; } /* * Enforce IPsec policy checking if we are seeing last header. * note that we do not visit this with protocols with pcb layer * code - like udp/tcp/raw ip. */ if (ipsec6_lasthdr(nxt) && ipsec6_in_reject(m, NULL)) { error = EINVAL; goto bad; } nxt = ip6_protox[nxt](&m, &skip, nxt); } NET_EPOCH_EXIT(et); key_freesav(&sav); return (0); bad: NET_EPOCH_EXIT(et); key_freesav(&sav); if (m) m_freem(m); return (error); } #endif /* INET6 */