/* $NetBSD: ipsec_output.c,v 1.85.4.1 2024/07/20 14:34:24 martin Exp $ */ /* * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD: sys/netipsec/ipsec_output.c,v 1.3.2.2 2003/03/28 20:32:53 sam Exp $ */ #include __KERNEL_RCSID(0, "$NetBSD: ipsec_output.c,v 1.85.4.1 2024/07/20 14:34:24 martin Exp $"); #if defined(_KERNEL_OPT) #include "opt_inet.h" #include "opt_net_mpsafe.h" #endif #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 #include #include #include #ifdef INET6 #include #endif #include #include #include #include #include #include #include static percpu_t *ipsec_rtcache_percpu __cacheline_aligned; /* * Add a IPSEC_OUT_DONE tag to mark that we have finished the ipsec processing * It will be used by ip{,6}_output to check if we have already or not * processed this packet. */ static int ipsec_register_done(struct mbuf *m, int *error) { struct m_tag *mtag; mtag = m_tag_get(PACKET_TAG_IPSEC_OUT_DONE, 0, M_NOWAIT); if (mtag == NULL) { IPSECLOG(LOG_DEBUG, "could not get packet tag\n"); *error = ENOMEM; return -1; } m_tag_prepend(m, mtag); return 0; } static int ipsec_reinject_ipstack(struct mbuf *m, int af, int flags) { int rv = -1; struct route *ro; KASSERT(af == AF_INET || af == AF_INET6); KERNEL_LOCK_UNLESS_NET_MPSAFE(); ro = rtcache_percpu_getref(ipsec_rtcache_percpu); switch (af) { #ifdef INET case AF_INET: rv = ip_output(m, NULL, ro, IP_RAWOUTPUT|IP_NOIPNEWID, NULL, NULL); break; #endif #ifdef INET6 case AF_INET6: /* * We don't need massage, IPv6 header fields are always in * net endian. */ rv = ip6_output(m, NULL, ro, flags, NULL, NULL, NULL); break; #endif } rtcache_percpu_putref(ipsec_rtcache_percpu); KERNEL_UNLOCK_UNLESS_NET_MPSAFE(); return rv; } int ipsec_process_done(struct mbuf *m, const struct ipsecrequest *isr, struct secasvar *sav, int flags) { struct secasindex *saidx; int error; #ifdef INET struct ip *ip; #endif #ifdef INET6 struct ip6_hdr *ip6; #endif struct mbuf *mo; struct udphdr *udp = NULL; int hlen, roff, iphlen; KASSERT(m != NULL); KASSERT(isr != NULL); KASSERT(sav != NULL); saidx = &sav->sah->saidx; if (sav->natt_type != 0) { hlen = sizeof(struct udphdr); switch (saidx->dst.sa.sa_family) { #ifdef INET case AF_INET: ip = mtod(m, struct ip *); mo = m_makespace(m, sizeof(struct ip), hlen, &roff); iphlen = ip->ip_hl << 2; break; #endif #ifdef INET6 case AF_INET6: ip6 = mtod(m, struct ip6_hdr *); mo = m_makespace(m, sizeof(struct ip6_hdr), hlen, &roff); iphlen = sizeof(*ip6); break; #endif default: IPSECLOG(LOG_DEBUG, "unknown protocol family %u\n", saidx->dst.sa.sa_family); error = ENXIO; goto bad; } if (mo == NULL) { char buf[IPSEC_ADDRSTRLEN]; IPSECLOG(LOG_DEBUG, "failed to inject %u byte UDP for SA %s/%08lx\n", hlen, ipsec_address(&saidx->dst, buf, sizeof(buf)), (u_long)ntohl(sav->spi)); error = ENOBUFS; goto bad; } udp = (struct udphdr *)(mtod(mo, char *) + roff); udp->uh_sport = key_portfromsaddr(&saidx->src); udp->uh_dport = key_portfromsaddr(&saidx->dst); udp->uh_sum = 0; udp->uh_ulen = htons(m->m_pkthdr.len - iphlen); } /* * Fix the header length, for AH processing. */ switch (saidx->dst.sa.sa_family) { #ifdef INET case AF_INET: ip = mtod(m, struct ip *); ip->ip_len = htons(m->m_pkthdr.len); /* IPv4 packet does not have to be set UDP checksum. */ if (sav->natt_type != 0) ip->ip_p = IPPROTO_UDP; break; #endif #ifdef INET6 case AF_INET6: if (m->m_pkthdr.len < sizeof(struct ip6_hdr)) { error = ENXIO; goto bad; } if (m->m_pkthdr.len - sizeof(struct ip6_hdr) > IPV6_MAXPACKET) { /* No jumbogram support. */ error = ENXIO; /*?*/ goto bad; } ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr)); /* IPv6 packet should be set UDP checksum. */ if (sav->natt_type != 0) { ip6->ip6_nxt = IPPROTO_UDP; ipsec6_udp_cksum(m); } break; #endif default: IPSECLOG(LOG_DEBUG, "unknown protocol family %u\n", saidx->dst.sa.sa_family); error = ENXIO; goto bad; } key_sa_recordxfer(sav, m); /* * If there's another (bundled) SA to apply, do so. * Note that this puts a burden on the kernel stack size. * If this is a problem we'll need to introduce a queue * to set the packet on so we can unwind the stack before * doing further processing. */ if (isr->next) { IPSEC_STATINC(IPSEC_STAT_OUT_BUNDLESA); switch (saidx->dst.sa.sa_family) { #ifdef INET case AF_INET: return ipsec4_process_packet(m, isr->next, NULL); #endif #ifdef INET6 case AF_INET6: return ipsec6_process_packet(m, isr->next, flags); #endif default: IPSECLOG(LOG_DEBUG, "unknown protocol family %u\n", saidx->dst.sa.sa_family); error = ENXIO; goto bad; } } /* * We're done with IPsec processing, mark the packet as processed, * and transmit it using the appropriate network protocol * (IPv4/IPv6). */ if (ipsec_register_done(m, &error) < 0) goto bad; return ipsec_reinject_ipstack(m, saidx->dst.sa.sa_family, flags); bad: m_freem(m); return error; } static void ipsec_fill_saidx_bymbuf(struct secasindex *saidx, const struct mbuf *m, const int af) { struct m_tag *mtag; u_int16_t natt_src = IPSEC_PORT_ANY; u_int16_t natt_dst = IPSEC_PORT_ANY; /* * For NAT-T enabled ipsecif(4), set NAT-T port numbers * even if the saidx uses transport mode. * * See also ipsecif[46]_output(). */ mtag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS); if (mtag) { u_int16_t *natt_ports; natt_ports = (u_int16_t *)(mtag + 1); natt_src = natt_ports[1]; natt_dst = natt_ports[0]; } if (af == AF_INET) { struct sockaddr_in *sin; struct ip *ip = mtod(m, struct ip *); if (saidx->src.sa.sa_len == 0) { sin = &saidx->src.sin; sin->sin_len = sizeof(*sin); sin->sin_family = AF_INET; sin->sin_port = natt_src; sin->sin_addr = ip->ip_src; } if (saidx->dst.sa.sa_len == 0) { sin = &saidx->dst.sin; sin->sin_len = sizeof(*sin); sin->sin_family = AF_INET; sin->sin_port = natt_dst; sin->sin_addr = ip->ip_dst; } } else { struct sockaddr_in6 *sin6; struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); if (saidx->src.sin6.sin6_len == 0) { sin6 = (struct sockaddr_in6 *)&saidx->src; sin6->sin6_len = sizeof(*sin6); sin6->sin6_family = AF_INET6; sin6->sin6_port = natt_src; sin6->sin6_addr = ip6->ip6_src; if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) { /* fix scope id for comparing SPD */ sin6->sin6_addr.s6_addr16[1] = 0; sin6->sin6_scope_id = ntohs(ip6->ip6_src.s6_addr16[1]); } } if (saidx->dst.sin6.sin6_len == 0) { sin6 = (struct sockaddr_in6 *)&saidx->dst; sin6->sin6_len = sizeof(*sin6); sin6->sin6_family = AF_INET6; sin6->sin6_port = natt_dst; sin6->sin6_addr = ip6->ip6_dst; if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) { /* fix scope id for comparing SPD */ sin6->sin6_addr.s6_addr16[1] = 0; sin6->sin6_scope_id = ntohs(ip6->ip6_dst.s6_addr16[1]); } } } } struct secasvar * ipsec_lookup_sa(const struct ipsecrequest *isr, const struct mbuf *m) { struct secasindex saidx; saidx = isr->saidx; if (isr->saidx.mode == IPSEC_MODE_TRANSPORT) { /* Fillin unspecified SA peers only for transport mode */ ipsec_fill_saidx_bymbuf(&saidx, m, isr->saidx.dst.sa.sa_family); } return key_lookup_sa_bysaidx(&saidx); } /* * ipsec_nextisr can return : * - isr == NULL and error != 0 => something is bad : the packet must be * discarded * - isr == NULL and error == 0 => no more rules to apply, ipsec processing * is done, reinject it in ip stack * - isr != NULL (error == 0) => we need to apply one rule to the packet */ static const struct ipsecrequest * ipsec_nextisr(struct mbuf *m, const struct ipsecrequest *isr, int af, int *error, struct secasvar **ret) { #define IPSEC_OSTAT(type) \ do { \ switch (isr->saidx.proto) { \ case IPPROTO_ESP: \ ESP_STATINC(ESP_STAT_ ## type); \ break; \ case IPPROTO_AH: \ AH_STATINC(AH_STAT_ ## type); \ break; \ default: \ IPCOMP_STATINC(IPCOMP_STAT_ ## type); \ break; \ } \ } while (/*CONSTCOND*/0) struct secasvar *sav = NULL; struct secasindex saidx; KASSERTMSG(af == AF_INET || af == AF_INET6, "invalid address family %u", af); again: /* * Craft SA index to search for proper SA. Note that * we only fillin unspecified SA peers for transport * mode; for tunnel mode they must already be filled in. */ saidx = isr->saidx; if (isr->saidx.mode == IPSEC_MODE_TRANSPORT) { /* Fillin unspecified SA peers only for transport mode */ ipsec_fill_saidx_bymbuf(&saidx, m, af); } /* * Lookup SA and validate it. */ *error = key_checkrequest(isr, &saidx, &sav); if (*error != 0) { /* * IPsec processing is required, but no SA found. * I assume that key_acquire() had been called * to get/establish the SA. Here I discard * this packet because it is responsibility for * upper layer to retransmit the packet. */ IPSEC_STATINC(IPSEC_STAT_OUT_NOSA); goto bad; } /* sav may be NULL here if we have an USE rule */ if (sav == NULL) { KASSERTMSG(ipsec_get_reqlevel(isr) == IPSEC_LEVEL_USE, "no SA found, but required; level %u", ipsec_get_reqlevel(isr)); isr = isr->next; /* * No more rules to apply, return NULL isr and no error. * It can happen when the last rules are USE rules. */ if (isr == NULL) { *ret = NULL; *error = 0; return isr; } goto again; } /* * Check system global policy controls. */ if ((isr->saidx.proto == IPPROTO_ESP && !esp_enable) || (isr->saidx.proto == IPPROTO_AH && !ah_enable) || (isr->saidx.proto == IPPROTO_IPCOMP && !ipcomp_enable)) { IPSECLOG(LOG_DEBUG, "IPsec outbound packet dropped due" " to policy (check your sysctls)\n"); IPSEC_OSTAT(PDROPS); *error = EHOSTUNREACH; KEY_SA_UNREF(&sav); goto bad; } /* * Sanity check the SA contents for the caller * before they invoke the xform output method. */ KASSERT(sav->tdb_xform != NULL); *ret = sav; return isr; bad: KASSERTMSG(*error != 0, "error return w/ no error code"); return NULL; #undef IPSEC_OSTAT } #ifdef INET /* * IPsec output logic for IPv4. */ int ipsec4_process_packet(struct mbuf *m, const struct ipsecrequest *isr, u_long *mtu) { struct secasvar *sav = NULL; struct ip *ip; int error, i, off; union sockaddr_union *dst; int setdf; KASSERT(m != NULL); KASSERT(m->m_nextpkt == NULL); KASSERT(isr != NULL); isr = ipsec_nextisr(m, isr, AF_INET, &error, &sav); if (isr == NULL) { if (error != 0) { goto bad; } else { if (ipsec_register_done(m, &error) < 0) goto bad; return ipsec_reinject_ipstack(m, AF_INET, 0); } } KASSERT(sav != NULL); if (m->m_len < sizeof(struct ip) && (m = m_pullup(m, sizeof(struct ip))) == NULL) { error = ENOBUFS; goto unrefsav; } /* * Check if we need to handle NAT-T fragmentation. */ if (isr == isr->sp->req) { /* Check only if called from ipsec4_output */ KASSERT(mtu != NULL); ip = mtod(m, struct ip *); if (!(sav->natt_type & UDP_ENCAP_ESPINUDP)) { goto noneed; } if (ntohs(ip->ip_len) <= sav->esp_frag) goto noneed; *mtu = sav->esp_frag; KEY_SA_UNREF(&sav); return 0; } noneed: dst = &sav->sah->saidx.dst; /* * Collect IP_DF state from the outer header. */ if (dst->sa.sa_family == AF_INET) { ip = mtod(m, struct ip *); /* Honor system-wide control of how to handle IP_DF */ switch (ip4_ipsec_dfbit) { case 0: /* clear in outer header */ case 1: /* set in outer header */ setdf = ip4_ipsec_dfbit; break; default: /* propagate to outer header */ setdf = ip->ip_off; setdf = ntohs(setdf); setdf = htons(setdf & IP_DF); break; } } else { ip = NULL; /* keep compiler happy */ setdf = 0; } /* Do the appropriate encapsulation, if necessary */ if (isr->saidx.mode == IPSEC_MODE_TUNNEL || /* Tunnel requ'd */ dst->sa.sa_family != AF_INET || /* PF mismatch */ (dst->sa.sa_family == AF_INET && /* Proxy */ dst->sin.sin_addr.s_addr != INADDR_ANY && dst->sin.sin_addr.s_addr != ip->ip_dst.s_addr)) { struct mbuf *mp; /* Fix IPv4 header checksum and length */ 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); /* Encapsulate the packet */ error = ipip_output(m, sav, &mp); if (mp == NULL && !error) { /* Should never happen. */ IPSECLOG(LOG_DEBUG, "ipip_output returns no mbuf and no error!"); error = EFAULT; } if (error) { if (mp) { /* XXX: Should never happen! */ m_freem(mp); } m = NULL; /* ipip_output() already freed it */ goto unrefsav; } m = mp, mp = NULL; /* * ipip_output clears IP_DF in the new header. If * we need to propagate IP_DF from the outer header, * then we have to do it here. * * XXX shouldn't assume what ipip_output does. */ if (dst->sa.sa_family == AF_INET && setdf) { if (m->m_len < sizeof(struct ip) && (m = m_pullup(m, sizeof(struct ip))) == NULL) { error = ENOBUFS; goto unrefsav; } ip = mtod(m, struct ip *); ip->ip_off |= htons(IP_DF); } } /* * Dispatch to the appropriate IPsec transform logic. The * packet will be returned for transmission after crypto * processing, etc. are completed. For encapsulation we * bypass this call because of the explicit call done above * (necessary to deal with IP_DF handling for IPv4). * * NB: m & sav are ``passed to caller'' who's responsible for * for reclaiming their resources. */ if (sav->tdb_xform->xf_type != XF_IP4) { if (dst->sa.sa_family == AF_INET) { ip = mtod(m, struct ip *); i = ip->ip_hl << 2; off = offsetof(struct ip, ip_p); } else { i = sizeof(struct ip6_hdr); off = offsetof(struct ip6_hdr, ip6_nxt); } error = (*sav->tdb_xform->xf_output)(m, isr, sav, i, off, 0); } else { error = ipsec_process_done(m, isr, sav, 0); } KEY_SA_UNREF(&sav); return error; unrefsav: KEY_SA_UNREF(&sav); bad: if (m) m_freem(m); return error; } #endif #ifdef INET6 static int compute_ipsec_pos(struct mbuf *m, int *i, int *off) { struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); struct ip6_ext ip6e; int dstopt = 0; int nxt; *i = sizeof(struct ip6_hdr); *off = offsetof(struct ip6_hdr, ip6_nxt); nxt = ip6->ip6_nxt; /* * chase mbuf chain to find the appropriate place to * put AH/ESP/IPcomp header. * IPv6 hbh dest1 rthdr ah* [esp* dest2 payload] */ while (1) { switch (nxt) { case IPPROTO_AH: case IPPROTO_ESP: case IPPROTO_IPCOMP: /* * We should not skip security header added * beforehand. */ return 0; case IPPROTO_HOPOPTS: case IPPROTO_DSTOPTS: case IPPROTO_ROUTING: if (*i + sizeof(ip6e) > m->m_pkthdr.len) { return EINVAL; } /* * If we see 2nd destination option header, * we should stop there. */ if (nxt == IPPROTO_DSTOPTS && dstopt) return 0; if (nxt == IPPROTO_DSTOPTS) { /* * Seen 1st or 2nd destination option. * next time we see one, it must be 2nd. */ dstopt = 1; } else if (nxt == IPPROTO_ROUTING) { /* * If we see destination option next * time, it must be dest2. */ dstopt = 2; } /* skip this header */ m_copydata(m, *i, sizeof(ip6e), &ip6e); nxt = ip6e.ip6e_nxt; *off = *i + offsetof(struct ip6_ext, ip6e_nxt); *i += (ip6e.ip6e_len + 1) << 3; if (*i > m->m_pkthdr.len) { return EINVAL; } break; default: return 0; } } return 0; } static int in6_sa_equal_addrwithscope(const struct sockaddr_in6 *sa, const struct in6_addr *ia) { struct in6_addr ia2; memcpy(&ia2, &sa->sin6_addr, sizeof(ia2)); if (IN6_IS_SCOPE_LINKLOCAL(&sa->sin6_addr)) ia2.s6_addr16[1] = htons(sa->sin6_scope_id); return IN6_ARE_ADDR_EQUAL(ia, &ia2); } int ipsec6_process_packet(struct mbuf *m, const struct ipsecrequest *isr, int flags) { struct secasvar *sav = NULL; struct ip6_hdr *ip6; int error, i, off; union sockaddr_union *dst; KASSERT(m != NULL); KASSERT(m->m_nextpkt == NULL); KASSERT(isr != NULL); isr = ipsec_nextisr(m, isr, AF_INET6, &error, &sav); if (isr == NULL) { if (error != 0) { /* XXX Should we send a notification ? */ goto bad; } else { if (ipsec_register_done(m, &error) < 0) goto bad; return ipsec_reinject_ipstack(m, AF_INET6, flags); } } KASSERT(sav != NULL); dst = &sav->sah->saidx.dst; if (m->m_len < sizeof(struct ip6_hdr)) { if ((m = m_pullup(m,sizeof(struct ip6_hdr))) == NULL) { error = ENOBUFS; goto unrefsav; } } ip6 = mtod(m, struct ip6_hdr *); /* Do the appropriate encapsulation, if necessary */ if (isr->saidx.mode == IPSEC_MODE_TUNNEL || /* Tunnel requ'd */ dst->sa.sa_family != AF_INET6 || /* AF mismatch */ ((dst->sa.sa_family == AF_INET6) && (!IN6_IS_ADDR_UNSPECIFIED(&dst->sin6.sin6_addr)) && (!in6_sa_equal_addrwithscope(&dst->sin6, &ip6->ip6_dst)))) { struct mbuf *mp; if (m->m_pkthdr.len - sizeof(*ip6) > IPV6_MAXPACKET) { /* No jumbogram support. */ error = ENXIO; /*XXX*/ goto unrefsav; } /* Fix IPv6 header payload length. */ ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6)); /* Encapsulate the packet */ error = ipip_output(m, sav, &mp); if (mp == NULL && !error) { /* Should never happen. */ IPSECLOG(LOG_DEBUG, "ipip_output returns no mbuf and no error!"); error = EFAULT; } if (error) { if (mp) { /* XXX: Should never happen! */ m_freem(mp); } m = NULL; /* ipip_output() already freed it */ goto unrefsav; } m = mp; mp = NULL; } if (dst->sa.sa_family == AF_INET) { struct ip *ip; ip = mtod(m, struct ip *); i = ip->ip_hl << 2; off = offsetof(struct ip, ip_p); } else { error = compute_ipsec_pos(m, &i, &off); if (error) goto unrefsav; } error = (*sav->tdb_xform->xf_output)(m, isr, sav, i, off, flags); KEY_SA_UNREF(&sav); return error; unrefsav: KEY_SA_UNREF(&sav); bad: if (m) m_freem(m); return error; } #endif /* INET6 */ void ipsec_output_init(void) { ipsec_rtcache_percpu = rtcache_percpu_alloc(); }