/* $NetBSD: ipsec_input.c,v 1.75 2019/01/27 02:08:48 pgoyette Exp $ */ /* $FreeBSD: ipsec_input.c,v 1.2.4.2 2003/03/28 20:32:53 sam Exp $ */ /* $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. * * 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. */ #include __KERNEL_RCSID(0, "$NetBSD: ipsec_input.c,v 1.75 2019/01/27 02:08:48 pgoyette Exp $"); /* * IPsec input processing. */ #if defined(_KERNEL_OPT) #include "opt_inet.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #include #include #endif #include #include #include #ifdef INET6 #include #endif #include #include #include #include #include #include #include #include #define IPSEC_ISTAT(p, x, y, z) \ do { \ switch (p) { \ case IPPROTO_ESP: \ ESP_STATINC(x); \ break; \ case IPPROTO_AH: \ AH_STATINC(y); \ break; \ default: \ IPCOMP_STATINC(z); \ break; \ } \ } while (/*CONSTCOND*/0) /* * fixup TCP/UDP checksum * * XXX: if we have NAT-OA payload from IKE server, * we must do the differential update of checksum. * * XXX: NAT-OAi/NAT-OAr drived from IKE initiator/responder. * how to know the IKE side from kernel? */ static struct mbuf * ipsec4_fixup_checksum(struct mbuf *m) { struct ip *ip; struct tcphdr *th; struct udphdr *uh; int poff, off; int plen; if (m->m_len < sizeof(*ip)) { m = m_pullup(m, sizeof(*ip)); if (m == NULL) return NULL; } ip = mtod(m, struct ip *); poff = ip->ip_hl << 2; plen = ntohs(ip->ip_len) - poff; switch (ip->ip_p) { case IPPROTO_TCP: M_REGION_GET(th, struct tcphdr *, m, poff, sizeof(*th)); if (th == NULL) return NULL; off = th->th_off << 2; if (off < sizeof(*th) || off > plen) { m_freem(m); return NULL; } th->th_sum = 0; th->th_sum = in4_cksum(m, IPPROTO_TCP, poff, plen); break; case IPPROTO_UDP: M_REGION_GET(uh, struct udphdr *, m, poff, sizeof(*uh)); if (uh == NULL) return NULL; off = sizeof(*uh); if (off > plen) { m_freem(m); return NULL; } uh->uh_sum = 0; uh->uh_sum = in4_cksum(m, IPPROTO_UDP, poff, plen); break; default: /* no checksum */ return m; } return m; } static void nat_t_ports_get(struct mbuf *m, uint16_t *dport, uint16_t *sport) { struct m_tag *tag; if ((tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS))) { *sport = ((uint16_t *)(tag + 1))[0]; *dport = ((uint16_t *)(tag + 1))[1]; } else *sport = *dport = 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) { char buf[IPSEC_ADDRSTRLEN]; union sockaddr_union dst_address; struct secasvar *sav; u_int32_t spi; u_int16_t sport; u_int16_t dport; int s, error; IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT, IPCOMP_STAT_INPUT); KASSERT(m != NULL); if ((sproto == IPPROTO_ESP && !esp_enable) || (sproto == IPPROTO_AH && !ah_enable) || (sproto == IPPROTO_IPCOMP && !ipcomp_enable)) { m_freem(m); IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS, IPCOMP_STAT_PDROPS); return EOPNOTSUPP; } if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) { m_freem(m); IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, IPCOMP_STAT_HDROPS); IPSECLOG(LOG_DEBUG, "packet too small\n"); return EINVAL; } /* Retrieve the SPI from the relevant IPsec header */ if (sproto == IPPROTO_ESP) { m_copydata(m, skip, sizeof(u_int32_t), &spi); } else if (sproto == IPPROTO_AH) { m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t), &spi); } else if (sproto == IPPROTO_IPCOMP) { u_int16_t cpi; m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t), &cpi); spi = ntohl(htons(cpi)); } else { panic("%s called with bad protocol number: %d\n", __func__, sproto); } /* find the source port for NAT-T */ nat_t_ports_get(m, &dport, &sport); /* * 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. */ memset(&dst_address, 0, 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), &dst_address.sin.sin_addr); break; #endif #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), &dst_address.sin6.sin6_addr); if (sa6_recoverscope(&dst_address.sin6)) { m_freem(m); return EINVAL; } break; #endif default: IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af); m_freem(m); IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF, IPCOMP_STAT_NOPF); return EPFNOSUPPORT; } s = splsoftnet(); /* NB: only pass dst since key_lookup_sa follows RFC2401 */ sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport); if (sav == NULL) { IPSECLOG(LOG_DEBUG, "no key association found for SA %s/%08lx/%u/%u\n", ipsec_address(&dst_address, buf, sizeof(buf)), (u_long) ntohl(spi), sproto, ntohs(dport)); IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB, IPCOMP_STAT_NOTDB); splx(s); m_freem(m); return ENOENT; } KASSERT(sav->tdb_xform != NULL); /* * Call appropriate transform and return -- callback takes care of * everything else. */ error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff); KEY_SA_UNREF(&sav); splx(s); return error; } #ifdef INET /* * Common input handler for IPv4 AH, ESP, and IPCOMP. */ void ipsec4_common_input(struct mbuf *m, int off, int proto) { (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p), AF_INET, proto); } /* * 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) { int prot, af __diagused, sproto; struct ip *ip; struct secasindex *saidx; int error; if (__predict_false(m == NULL)) { panic("%s: NULL mbuf", __func__); } if (__predict_false(skip < sizeof(struct ip))) { panic("%s: short skip", __func__); } KASSERT(sav != NULL); saidx = &sav->sah->saidx; af = saidx->dst.sa.sa_family; KASSERTMSG(af == AF_INET, "unexpected af %u", af); sproto = saidx->proto; KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || sproto == IPPROTO_IPCOMP, "unexpected security protocol %u", sproto); /* * Update the IPv4 header. The length of the packet may have changed, * so fix it, and recompute the checksum. */ if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) { char buf[IPSEC_ADDRSTRLEN]; cantpull: IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), (u_long) ntohl(sav->spi)); IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, IPCOMP_STAT_HDROPS); error = ENOBUFS; goto bad; } 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); /* * Update TCP/UDP checksum * XXX: should only do it in NAT-T case * XXX: should do it incrementally, see FreeBSD code. */ m = ipsec4_fixup_checksum(m); if (m == NULL) goto cantpull; ip = mtod(m, struct ip *); prot = ip->ip_p; M_VERIFY_PACKET(m); key_sa_recordxfer(sav, m); if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 && ipsec_in_reject(m, NULL)) { error = EINVAL; goto bad; } /* * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, * so we cannot write filtering rule to the inner packet. */ if (saidx->mode == IPSEC_MODE_TUNNEL) m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot); return 0; bad: m_freem(m); return error; } #endif /* INET */ #ifdef INET6 int ipsec6_common_input(struct mbuf **mp, int *offp, int proto) { int l = 0; int protoff, nxt; struct ip6_ext ip6e; if (*offp < sizeof(struct ip6_hdr)) { IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp); IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, IPCOMP_STAT_HDROPS); m_freem(*mp); return IPPROTO_DONE; } else if (*offp == sizeof(struct ip6_hdr)) { protoff = offsetof(struct ip6_hdr, ip6_nxt); } else { /* Chase down the header chain... */ protoff = sizeof(struct ip6_hdr); nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt; do { protoff += l; m_copydata(*mp, protoff, sizeof(ip6e), &ip6e); if (nxt == IPPROTO_AH) l = (ip6e.ip6e_len + 2) << 2; else if (nxt == IPPROTO_FRAGMENT) l = sizeof(struct ip6_frag); else l = (ip6e.ip6e_len + 1) << 3; KASSERT(l > 0); nxt = ip6e.ip6e_nxt; } while (protoff + l < *offp); /* Malformed packet check */ if (protoff + l != *offp) { IPSECLOG(LOG_DEBUG, "bad packet header chain, " "protoff %u, l %u, off %u\n", protoff, l, *offp); IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS, IPCOMP_STAT_HDROPS); m_freem(*mp); *mp = NULL; return IPPROTO_DONE; } protoff += offsetof(struct ip6_ext, ip6e_nxt); } (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto); return IPPROTO_DONE; } /* * 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) { int af __diagused, sproto; struct ip6_hdr *ip6; struct secasindex *saidx; int nxt; u_int8_t prot; int error, nest; if (__predict_false(m == NULL)) { panic("%s: NULL mbuf", __func__); } KASSERT(sav != NULL); saidx = &sav->sah->saidx; af = saidx->dst.sa.sa_family; KASSERTMSG(af == AF_INET6, "unexpected af %u", af); sproto = saidx->proto; KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH || sproto == IPPROTO_IPCOMP, "unexpected security protocol %u", sproto); /* Fix IPv6 header */ if (m->m_len < sizeof(struct ip6_hdr) && (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { char buf[IPSEC_ADDRSTRLEN]; IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n", ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), (u_long) ntohl(sav->spi)); IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS, IPCOMP_STAT_HDROPS); error = EACCES; goto bad; } ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); m_copydata(m, protoff, sizeof(prot), &prot); key_sa_recordxfer(sav, m); /* * See the end of ip6_input for this logic. * IPPROTO_IPV[46] case will be processed just like other ones */ nest = 0; nxt = prot; while (nxt != IPPROTO_DONE) { if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) { IP6_STATINC(IP6_STAT_TOOMANYHDR); error = EINVAL; goto bad; } M_VERIFY_PACKET(m); /* * Protection against faulty packet - there should be * more sanity checks in header chain processing. */ if (m->m_pkthdr.len < skip) { IP6_STATINC(IP6_STAT_TOOSHORT); in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), 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 ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 && ipsec_in_reject(m, NULL)) { error = EINVAL; goto bad; } /* * There is no struct ifnet for tunnel mode IP-IP tunnel connecttion, * so we cannot write filtering rule to the inner packet. */ if (saidx->mode == IPSEC_MODE_TUNNEL) m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL; nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt); } return 0; bad: if (m) m_freem(m); return error; } #endif /* INET6 */