/* * Copyright (c) 2000-2023 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* $FreeBSD: src/sys/netinet6/frag6.c,v 1.2.2.5 2001/07/03 11:01:50 ume Exp $ */ /* $KAME: frag6.c,v 1.31 2001/05/17 13:45:34 jinmei Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * 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. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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. */ #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 /* * Define it to get a correct behavior on per-interface statistics. */ #define IN6_IFSTAT_STRICT struct ip6asfrag { struct ip6asfrag *ip6af_down; struct ip6asfrag *ip6af_up; struct mbuf *ip6af_m; int ip6af_offset; /* offset in ip6af_m to next header */ int ip6af_frglen; /* fragmentable part length */ int ip6af_off; /* fragment offset */ u_int16_t ip6af_mff; /* more fragment bit in frag off */ }; #define IP6_REASS_MBUF(ip6af) ((ip6af)->ip6af_m) MBUFQ_HEAD(fq6_head); static void frag6_save_context(struct mbuf *, int); static void frag6_scrub_context(struct mbuf *); static int frag6_restore_context(struct mbuf *); static void frag6_icmp6_paramprob_error(struct fq6_head *); static void frag6_icmp6_timeex_error(struct fq6_head *); static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *); static void frag6_deq(struct ip6asfrag *); static void frag6_insque(struct ip6q *, struct ip6q *); static void frag6_remque(struct ip6q *); static void frag6_purgef(struct ip6q *, struct fq6_head *, struct fq6_head *); static void frag6_freef(struct ip6q *, struct fq6_head *, struct fq6_head *); static int frag6_timeout_run; /* frag6 timer is scheduled to run */ static void frag6_timeout(void *); static void frag6_sched_timeout(void); static struct ip6q *ip6q_alloc(void); static void ip6q_free(struct ip6q *); static void ip6q_updateparams(void); static struct ip6asfrag *ip6af_alloc(void); static void ip6af_free(struct ip6asfrag *); static LCK_GRP_DECLARE(ip6qlock_grp, "ip6qlock"); static LCK_MTX_DECLARE(ip6qlock, &ip6qlock_grp); /* IPv6 fragment reassembly queues (protected by ip6qlock) */ static struct ip6q ip6q; /* ip6 reassembly queues */ static int ip6_maxfragpackets; /* max packets in reass queues */ static u_int32_t frag6_nfragpackets; /* # of packets in reass queues */ static int ip6_maxfrags; /* max fragments in reass queues */ static u_int32_t frag6_nfrags; /* # of fragments in reass queues */ static u_int32_t ip6q_limit; /* ip6q allocation limit */ static u_int32_t ip6q_count; /* current # of allocated ip6q's */ static u_int32_t ip6af_limit; /* ip6asfrag allocation limit */ static u_int32_t ip6af_count; /* current # of allocated ip6asfrag's */ static int sysctl_maxfragpackets SYSCTL_HANDLER_ARGS; static int sysctl_maxfrags SYSCTL_HANDLER_ARGS; SYSCTL_DECL(_net_inet6_ip6); SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &ip6_maxfragpackets, 0, sysctl_maxfragpackets, "I", "Maximum number of IPv6 fragment reassembly queue entries"); SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, fragpackets, CTLFLAG_RD | CTLFLAG_LOCKED, &frag6_nfragpackets, 0, "Current number of IPv6 fragment reassembly queue entries"); SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &ip6_maxfrags, 0, sysctl_maxfrags, "I", "Maximum number of IPv6 fragments allowed"); /* * Initialise reassembly queue and fragment identifier. */ void frag6_init(void) { lck_mtx_lock(&ip6qlock); /* Initialize IPv6 reassembly queue. */ ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q; /* same limits as IPv4 */ ip6_maxfragpackets = nmbclusters / 32; ip6_maxfrags = ip6_maxfragpackets * 2; ip6q_updateparams(); lck_mtx_unlock(&ip6qlock); } static void frag6_save_context(struct mbuf *m, int val) { m->m_pkthdr.pkt_hdr = (void *)(uintptr_t)val; } static void frag6_scrub_context(struct mbuf *m) { m->m_pkthdr.pkt_hdr = NULL; } static int frag6_restore_context(struct mbuf *m) { return (int)m->m_pkthdr.pkt_hdr; } /* * Send any deferred ICMP param problem error messages; caller must not be * holding ip6qlock and is expected to have saved the per-packet parameter * value via frag6_save_context(). */ static void frag6_icmp6_paramprob_error(struct fq6_head *diq6) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_NOTOWNED); if (!MBUFQ_EMPTY(diq6)) { struct mbuf *merr, *merr_tmp; int param; MBUFQ_FOREACH_SAFE(merr, diq6, merr_tmp) { MBUFQ_REMOVE(diq6, merr); MBUFQ_NEXT(merr) = NULL; param = frag6_restore_context(merr); frag6_scrub_context(merr); icmp6_error(merr, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, param); } } } /* * Send any deferred ICMP time exceeded error messages; * caller must not be holding ip6qlock. */ static void frag6_icmp6_timeex_error(struct fq6_head *diq6) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_NOTOWNED); if (!MBUFQ_EMPTY(diq6)) { struct mbuf *m, *m_tmp; MBUFQ_FOREACH_SAFE(m, diq6, m_tmp) { MBUFQ_REMOVE(diq6, m); MBUFQ_NEXT(m) = NULL; icmp6_error_flag(m, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_REASSEMBLY, 0, 0); } } } /* * In RFC2460, fragment and reassembly rule do not agree with each other, * in terms of next header field handling in fragment header. * While the sender will use the same value for all of the fragmented packets, * receiver is suggested not to check the consistency. * * fragment rule (p20): * (2) A Fragment header containing: * The Next Header value that identifies the first header of * the Fragmentable Part of the original packet. * -> next header field is same for all fragments * * reassembly rule (p21): * The Next Header field of the last header of the Unfragmentable * Part is obtained from the Next Header field of the first * fragment's Fragment header. * -> should grab it from the first fragment only * * The following note also contradicts with fragment rule - noone is going to * send different fragment with different next header field. * * additional note (p22): * The Next Header values in the Fragment headers of different * fragments of the same original packet may differ. Only the value * from the Offset zero fragment packet is used for reassembly. * -> should grab it from the first fragment only * * There is no explicit reason given in the RFC. Historical reason maybe? */ /* * Fragment input */ int frag6_input(struct mbuf **mp, int *offp, int proto) { #pragma unused(proto) struct mbuf *m = *mp, *t = NULL; struct ip6_hdr *ip6 = NULL; struct ip6_frag *ip6f = NULL; struct ip6q *q6 = NULL; struct ip6asfrag *af6 = NULL, *ip6af = NULL, *af6dwn = NULL; int offset = *offp, i = 0, next = 0; u_int8_t nxt = 0; int first_frag = 0; int fragoff = 0, frgpartlen = 0; /* must be larger than u_int16_t */ struct ifnet *dstifp = NULL; u_int8_t ecn = 0, ecn0 = 0; uint32_t csum = 0, csum_flags = 0; struct fq6_head diq6 = {}; int locked = 0; boolean_t drop_fragq = FALSE; int local_ip6q_unfrglen; u_int8_t local_ip6q_nxt; VERIFY(m->m_flags & M_PKTHDR); MBUFQ_INIT(&diq6); /* for deferred ICMP param problem errors */ /* Expect 32-bit aligned data pointer on strict-align platforms */ MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), goto done); ip6 = mtod(m, struct ip6_hdr *); ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); #ifdef IN6_IFSTAT_STRICT /* find the destination interface of the packet. */ if (m->m_pkthdr.pkt_flags & PKTF_IFAINFO) { uint32_t idx; if (ip6_getdstifaddr_info(m, &idx, NULL) == 0) { if (idx > 0 && idx <= if_index) { ifnet_head_lock_shared(); dstifp = ifindex2ifnet[idx]; ifnet_head_done(); } } } #endif /* IN6_IFSTAT_STRICT */ /* we are violating the spec, this may not be the dst interface */ if (dstifp == NULL) { dstifp = m->m_pkthdr.rcvif; } /* jumbo payload can't contain a fragment header */ if (ip6->ip6_plen == 0) { icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset); in6_ifstat_inc(dstifp, ifs6_reass_fail); m = NULL; goto done; } /* * check whether fragment packet's fragment length is * multiple of 8 octets. * sizeof(struct ip6_frag) == 8 * sizeof(struct ip6_hdr) = 40 */ if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) && (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) { icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offsetof(struct ip6_hdr, ip6_plen)); in6_ifstat_inc(dstifp, ifs6_reass_fail); m = NULL; goto done; } /* If ip6_maxfragpackets or ip6_maxfrags is 0, never accept fragments */ if (ip6_maxfragpackets == 0 || ip6_maxfrags == 0) { ip6stat.ip6s_fragments++; ip6stat.ip6s_fragdropped++; in6_ifstat_inc(dstifp, ifs6_reass_fail); m_freem(m); m = NULL; goto done; } /* offset now points to data portion */ offset += sizeof(struct ip6_frag); /* * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0) * upfront, unrelated to any reassembly. Just skip the fragment header. */ if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { /* * Mark packet as reassembled. * In ICMPv6 processing, we drop certain * NDP messages that are not expected to * have fragment header based on recommendations * against security vulnerability as described in * RFC 6980. * Treat atomic fragments as re-assembled packets as well. */ m->m_pkthdr.pkt_flags |= PKTF_REASSEMBLED; ip6stat.ip6s_atmfrag_rcvd++; in6_ifstat_inc(dstifp, ifs6_atmfrag_rcvd); *mp = m; *offp = offset; return ip6f->ip6f_nxt; } /* * Leverage partial checksum offload for simple UDP/IP fragments, * as that is the most common case. * * Perform 1's complement adjustment of octets that got included/ * excluded in the hardware-calculated checksum value. Also take * care of any trailing bytes and subtract out their partial sum. */ if (ip6f->ip6f_nxt == IPPROTO_UDP && offset == (sizeof(*ip6) + sizeof(*ip6f)) && (m->m_pkthdr.csum_flags & (CSUM_DATA_VALID | CSUM_PARTIAL | CSUM_PSEUDO_HDR)) == (CSUM_DATA_VALID | CSUM_PARTIAL)) { uint32_t start = m->m_pkthdr.csum_rx_start; uint32_t ip_len = (sizeof(*ip6) + ntohs(ip6->ip6_plen)); int32_t trailer = (m_pktlen(m) - ip_len); uint32_t swbytes = (uint32_t)trailer; csum = m->m_pkthdr.csum_rx_val; ASSERT(trailer >= 0); if (start != offset || trailer != 0) { uint16_t s = 0, d = 0; if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { s = ip6->ip6_src.s6_addr16[1]; ip6->ip6_src.s6_addr16[1] = 0; } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { d = ip6->ip6_dst.s6_addr16[1]; ip6->ip6_dst.s6_addr16[1] = 0; } /* callee folds in sum */ csum = m_adj_sum16(m, start, offset, (ip_len - offset), csum); if (offset > start) { swbytes += (offset - start); } else { swbytes += (start - offset); } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { ip6->ip6_src.s6_addr16[1] = s; } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { ip6->ip6_dst.s6_addr16[1] = d; } } csum_flags = m->m_pkthdr.csum_flags; if (swbytes != 0) { udp_in6_cksum_stats(swbytes); } if (trailer != 0) { m_adj(m, -trailer); } } else { csum = 0; csum_flags = 0; } /* Invalidate checksum */ m->m_pkthdr.csum_flags &= ~CSUM_DATA_VALID; ip6stat.ip6s_fragments++; in6_ifstat_inc(dstifp, ifs6_reass_reqd); lck_mtx_lock(&ip6qlock); locked = 1; for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next) { if (ip6f->ip6f_ident == q6->ip6q_ident && in6_are_addr_equal_scoped(&ip6->ip6_src, &q6->ip6q_src, ip6_input_getsrcifscope(m), q6->ip6q_src_ifscope) && in6_are_addr_equal_scoped(&ip6->ip6_dst, &q6->ip6q_dst, ip6_input_getdstifscope(m), q6->ip6q_dst_ifscope)) { break; } } if (q6 == &ip6q) { /* * Create a reassembly queue as this is the first fragment to * arrive. * By first frag, we don't mean the one with offset 0, but * any of the fragments of the fragmented packet that has * reached us first. */ first_frag = 1; q6 = ip6q_alloc(); if (q6 == NULL) { goto dropfrag; } frag6_insque(q6, &ip6q); frag6_nfragpackets++; /* ip6q_nxt will be filled afterwards, from 1st fragment */ q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6; #ifdef notyet q6->ip6q_nxtp = (u_char *)nxtp; #endif q6->ip6q_ident = ip6f->ip6f_ident; q6->ip6q_ttl = IPV6_FRAGTTL; q6->ip6q_src = ip6->ip6_src; q6->ip6q_dst = ip6->ip6_dst; q6->ip6q_dst_ifscope = IN6_IS_SCOPE_EMBED(&q6->ip6q_dst) ? ip6_input_getdstifscope(m) : IFSCOPE_NONE; q6->ip6q_src_ifscope = IN6_IS_SCOPE_EMBED(&q6->ip6q_src) ? ip6_input_getsrcifscope(m) : IFSCOPE_NONE; q6->ip6q_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ q6->ip6q_nfrag = 0; q6->ip6q_flags = 0; /* * If the first fragment has valid checksum offload * info, the rest of fragments are eligible as well. */ if (csum_flags != 0) { q6->ip6q_csum = csum; q6->ip6q_csum_flags = csum_flags; } } if (q6->ip6q_flags & IP6QF_DIRTY) { goto dropfrag; } local_ip6q_unfrglen = q6->ip6q_unfrglen; local_ip6q_nxt = q6->ip6q_nxt; /* * If it's the 1st fragment, record the length of the * unfragmentable part and the next header of the fragment header. * Assume the first fragement to arrive will be correct. * We do not have any duplicate checks here yet so another packet * with fragoff == 0 could come and overwrite the ip6q_unfrglen * and worse, the next header, at any time. */ fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); if (fragoff == 0 && local_ip6q_unfrglen == -1) { local_ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - sizeof(struct ip6_frag); local_ip6q_nxt = ip6f->ip6f_nxt; /* XXX ECN? */ } /* * Check that the reassembled packet would not exceed 65535 bytes * in size. * If it would exceed, discard the fragment and return an ICMP error. */ frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; if (local_ip6q_unfrglen >= 0) { /* The 1st fragment has already arrived. */ if (local_ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { lck_mtx_unlock(&ip6qlock); locked = 0; icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); m = NULL; goto done; } } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { lck_mtx_unlock(&ip6qlock); locked = 0; icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); m = NULL; goto done; } /* * If it's the first fragment, do the above check for each * fragment already stored in the reassembly queue. */ if (fragoff == 0) { /* * https://tools.ietf.org/html/rfc8200#page-20 * If the first fragment does not include all headers through an * Upper-Layer header, then that fragment should be discarded and * an ICMP Parameter Problem, Code 3, message should be sent to * the source of the fragment, with the Pointer field set to zero. */ if (!ip6_pkt_has_ulp(m)) { lck_mtx_unlock(&ip6qlock); locked = 0; icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_FIRSTFRAG_INCOMP_HDR, 0); m = NULL; goto done; } for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = af6dwn) { af6dwn = af6->ip6af_down; if (local_ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > IPV6_MAXPACKET) { struct mbuf *merr = IP6_REASS_MBUF(af6); struct ip6_hdr *ip6err; int erroff = af6->ip6af_offset; /* dequeue the fragment. */ frag6_deq(af6); ip6af_free(af6); /* adjust pointer. */ ip6err = mtod(merr, struct ip6_hdr *); /* * Restore source and destination addresses * in the erroneous IPv6 header. */ ip6err->ip6_src = q6->ip6q_src; ip6err->ip6_dst = q6->ip6q_dst; ip6_output_setdstifscope(m, q6->ip6q_dst_ifscope, NULL); ip6_output_setsrcifscope(m, q6->ip6q_src_ifscope, NULL); frag6_save_context(merr, erroff - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); MBUFQ_ENQUEUE(&diq6, merr); } } } ip6af = ip6af_alloc(); if (ip6af == NULL) { goto dropfrag; } ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG; ip6af->ip6af_off = fragoff; ip6af->ip6af_frglen = frgpartlen; ip6af->ip6af_offset = offset; IP6_REASS_MBUF(ip6af) = m; if (first_frag) { af6 = (struct ip6asfrag *)q6; goto insert; } /* * Handle ECN by comparing this segment with the first one; * if CE is set, do not lose CE. * drop if CE and not-ECT are mixed for the same packet. */ ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; ecn0 = q6->ip6q_ecn; if (ecn == IPTOS_ECN_CE) { if (ecn0 == IPTOS_ECN_NOTECT) { ip6af_free(ip6af); goto dropfrag; } if (ecn0 != IPTOS_ECN_CE) { q6->ip6q_ecn = IPTOS_ECN_CE; } } if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { ip6af_free(ip6af); goto dropfrag; } /* * Find a segment which begins after this one does. */ for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = af6->ip6af_down) { if (af6->ip6af_off > ip6af->ip6af_off) { break; } } /* * As per RFC 8200 reassembly rules, we MUST drop the entire * chain of fragments for a packet to be assembled, if we receive * any overlapping fragments. * https://tools.ietf.org/html/rfc8200#page-20 * * To avoid more conditional code, just reuse frag6_freef and defer * its call to post fragment insertion in the queue. */ if (af6->ip6af_up != (struct ip6asfrag *)q6) { if (af6->ip6af_up->ip6af_off == ip6af->ip6af_off) { if (af6->ip6af_up->ip6af_frglen != ip6af->ip6af_frglen) { drop_fragq = TRUE; } else { /* * XXX Ideally we should be comparing the entire * packet here but for now just use off and fraglen * to ignore a duplicate fragment. */ ip6af_free(ip6af); goto dropfrag; } } else { i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen - ip6af->ip6af_off; if (i > 0) { drop_fragq = TRUE; } } } if (af6 != (struct ip6asfrag *)q6) { /* * Given that we break when af6->ip6af_off > ip6af->ip6af_off, * we shouldn't need a check for duplicate fragment here. * For now just assert. */ VERIFY(af6->ip6af_off != ip6af->ip6af_off); i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; if (i > 0) { drop_fragq = TRUE; } } /* * If this fragment contains similar checksum offload info * as that of the existing ones, accumulate checksum. Otherwise, * invalidate checksum offload info for the entire datagram. */ if (csum_flags != 0 && csum_flags == q6->ip6q_csum_flags) { q6->ip6q_csum += csum; } else if (q6->ip6q_csum_flags != 0) { q6->ip6q_csum_flags = 0; } insert: /* * Stick new segment in its place; * check for complete reassembly. * Move to front of packet queue, as we are * the most recently active fragmented packet. */ frag6_enq(ip6af, af6->ip6af_up); frag6_nfrags++; q6->ip6q_nfrag++; /* * This holds true, when we receive overlapping fragments. * We must silently drop all the fragments we have received * so far. * Also mark q6 as dirty, so as to not add any new fragments to it. * Make sure even q6 marked dirty is kept till timer expires for * reassembly and when that happens, silenty get rid of q6 */ if (drop_fragq) { struct fq6_head dfq6 = {0}; MBUFQ_INIT(&dfq6); /* for deferred frees */ q6->ip6q_flags |= IP6QF_DIRTY; /* Purge all the fragments but do not free q6 */ frag6_purgef(q6, &dfq6, NULL); af6 = NULL; /* free fragments that need to be freed */ if (!MBUFQ_EMPTY(&dfq6)) { MBUFQ_DRAIN(&dfq6); } VERIFY(MBUFQ_EMPTY(&dfq6)); /* * Just in case the above logic got anything added * to diq6, drain it. * Please note that these mbufs are not present in the * fragment queue and are added to diq6 for sending * ICMPv6 error. * Given that the current fragment was an overlapping * fragment and the RFC requires us to not send any * ICMPv6 errors while purging the entire queue. * Just empty it out. */ if (!MBUFQ_EMPTY(&diq6)) { MBUFQ_DRAIN(&diq6); } VERIFY(MBUFQ_EMPTY(&diq6)); /* * MBUFQ_DRAIN would have drained all the mbufs * in the fragment queue. * This shouldn't be needed as we are returning IPPROTO_DONE * from here but change the passed mbuf pointer to NULL. */ *mp = NULL; lck_mtx_unlock(&ip6qlock); return IPPROTO_DONE; } /* * We're keeping the fragment. */ q6->ip6q_unfrglen = local_ip6q_unfrglen; q6->ip6q_nxt = local_ip6q_nxt; next = 0; for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = af6->ip6af_down) { if (af6->ip6af_off != next) { lck_mtx_unlock(&ip6qlock); locked = 0; m = NULL; goto done; } next += af6->ip6af_frglen; } if (af6->ip6af_up->ip6af_mff) { lck_mtx_unlock(&ip6qlock); locked = 0; m = NULL; goto done; } /* * Reassembly is complete; concatenate fragments. */ ip6af = q6->ip6q_down; t = m = IP6_REASS_MBUF(ip6af); af6 = ip6af->ip6af_down; frag6_deq(ip6af); while (af6 != (struct ip6asfrag *)q6) { af6dwn = af6->ip6af_down; frag6_deq(af6); while (t->m_next) { t = t->m_next; } t->m_next = IP6_REASS_MBUF(af6); m_adj(t->m_next, af6->ip6af_offset); ip6af_free(af6); af6 = af6dwn; } /* * Store partial hardware checksum info from the fragment queue; * the receive start offset is set to 40 bytes (see code at the * top of this routine.) */ if (q6->ip6q_csum_flags != 0) { csum = q6->ip6q_csum; ADDCARRY(csum); m->m_pkthdr.csum_rx_val = (u_int16_t)csum; m->m_pkthdr.csum_rx_start = sizeof(struct ip6_hdr); m->m_pkthdr.csum_flags = q6->ip6q_csum_flags; } else if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) || (m->m_pkthdr.pkt_flags & PKTF_LOOP)) { /* loopback checksums are always OK */ m->m_pkthdr.csum_data = 0xffff; m->m_pkthdr.csum_flags = CSUM_DATA_VALID | CSUM_PSEUDO_HDR; } /* adjust offset to point where the original next header starts */ offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); ip6af_free(ip6af); ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_plen = htons((uint16_t)(next + offset - sizeof(struct ip6_hdr))); ip6->ip6_src = q6->ip6q_src; ip6->ip6_dst = q6->ip6q_dst; ip6_output_setdstifscope(m, q6->ip6q_dst_ifscope, NULL); ip6_output_setsrcifscope(m, q6->ip6q_src_ifscope, NULL); if (q6->ip6q_ecn == IPTOS_ECN_CE) { ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); } nxt = q6->ip6q_nxt; #ifdef notyet *q6->ip6q_nxtp = (u_char)(nxt & 0xff); #endif /* Delete frag6 header */ if (m->m_len >= offset + sizeof(struct ip6_frag)) { /* This is the only possible case with !PULLDOWN_TEST */ ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag), offset); m->m_data += sizeof(struct ip6_frag); m->m_len -= sizeof(struct ip6_frag); } else { /* this comes with no copy if the boundary is on cluster */ if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) { frag6_remque(q6); frag6_nfragpackets--; frag6_nfrags -= q6->ip6q_nfrag; ip6q_free(q6); goto dropfrag; } m_adj(t, sizeof(struct ip6_frag)); m_cat(m, t); } /* * Store NXT to the original. */ { char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */ *prvnxtp = nxt; } frag6_remque(q6); frag6_nfragpackets--; frag6_nfrags -= q6->ip6q_nfrag; ip6q_free(q6); if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ m_fixhdr(m); /* * Mark packet as reassembled * In ICMPv6 processing, we drop certain * NDP messages that are not expected to * have fragment header based on recommendations * against security vulnerability as described in * RFC 6980. */ m->m_pkthdr.pkt_flags |= PKTF_REASSEMBLED; } ip6stat.ip6s_reassembled++; /* * Tell launch routine the next header */ *mp = m; *offp = offset; /* arm the purge timer if not already and if there's work to do */ frag6_sched_timeout(); lck_mtx_unlock(&ip6qlock); in6_ifstat_inc(dstifp, ifs6_reass_ok); frag6_icmp6_paramprob_error(&diq6); VERIFY(MBUFQ_EMPTY(&diq6)); return nxt; done: VERIFY(m == NULL); *mp = m; if (!locked) { if (frag6_nfragpackets == 0) { frag6_icmp6_paramprob_error(&diq6); VERIFY(MBUFQ_EMPTY(&diq6)); return IPPROTO_DONE; } lck_mtx_lock(&ip6qlock); } /* arm the purge timer if not already and if there's work to do */ frag6_sched_timeout(); lck_mtx_unlock(&ip6qlock); frag6_icmp6_paramprob_error(&diq6); VERIFY(MBUFQ_EMPTY(&diq6)); return IPPROTO_DONE; dropfrag: ip6stat.ip6s_fragdropped++; /* arm the purge timer if not already and if there's work to do */ frag6_sched_timeout(); lck_mtx_unlock(&ip6qlock); in6_ifstat_inc(dstifp, ifs6_reass_fail); m_freem(m); *mp = NULL; frag6_icmp6_paramprob_error(&diq6); VERIFY(MBUFQ_EMPTY(&diq6)); return IPPROTO_DONE; } /* * This routine removes the enqueued frames from the passed fragment * header and enqueues those to dfq6 which is an out-arg for the dequeued * fragments. * If the caller also provides diq6, this routine also enqueues the 0 offset * fragment to that list as it potentially gets used by the caller * to prepare the relevant ICMPv6 error message (time exceeded or * param problem). * It leaves the fragment header object (q6) intact. */ static void frag6_purgef(struct ip6q *q6, struct fq6_head *dfq6, struct fq6_head *diq6) { struct ip6asfrag *af6 = NULL; struct ip6asfrag *down6 = NULL; LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = down6) { struct mbuf *m = IP6_REASS_MBUF(af6); down6 = af6->ip6af_down; frag6_deq(af6); /* * If caller wants to generate ICMP time-exceeded, * as indicated by the argument diq6, return it for * the first fragment and add others to the fragment * free queue. */ if (af6->ip6af_off == 0 && diq6 != NULL) { struct ip6_hdr *ip6; /* adjust pointer */ ip6 = mtod(m, struct ip6_hdr *); /* restore source and destination addresses */ ip6->ip6_src = q6->ip6q_src; ip6->ip6_dst = q6->ip6q_dst; ip6_output_setdstifscope(m, q6->ip6q_dst_ifscope, NULL); ip6_output_setsrcifscope(m, q6->ip6q_src_ifscope, NULL); MBUFQ_ENQUEUE(diq6, m); } else { MBUFQ_ENQUEUE(dfq6, m); } ip6af_free(af6); } } /* * This routine removes the enqueued frames from the passed fragment * header and enqueues those to dfq6 which is an out-arg for the dequeued * fragments. * If the caller also provides diq6, this routine also enqueues the 0 offset * fragment to that list as it potentially gets used by the caller * to prepare the relevant ICMPv6 error message (time exceeded or * param problem). * It also remove the fragment header object from the queue and frees it. */ static void frag6_freef(struct ip6q *q6, struct fq6_head *dfq6, struct fq6_head *diq6) { frag6_purgef(q6, dfq6, diq6); frag6_remque(q6); frag6_nfragpackets--; frag6_nfrags -= q6->ip6q_nfrag; ip6q_free(q6); } /* * Put an ip fragment on a reassembly chain. * Like insque, but pointers in middle of structure. */ void frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); af6->ip6af_up = up6; af6->ip6af_down = up6->ip6af_down; up6->ip6af_down->ip6af_up = af6; up6->ip6af_down = af6; } /* * To frag6_enq as remque is to insque. */ void frag6_deq(struct ip6asfrag *af6) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); af6->ip6af_up->ip6af_down = af6->ip6af_down; af6->ip6af_down->ip6af_up = af6->ip6af_up; } void frag6_insque(struct ip6q *new, struct ip6q *old) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); new->ip6q_prev = old; new->ip6q_next = old->ip6q_next; old->ip6q_next->ip6q_prev = new; old->ip6q_next = new; } void frag6_remque(struct ip6q *p6) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); p6->ip6q_prev->ip6q_next = p6->ip6q_next; p6->ip6q_next->ip6q_prev = p6->ip6q_prev; } /* * IPv6 reassembling timer processing; * if a timer expires on a reassembly * queue, discard it. */ static void frag6_timeout(void *arg) { #pragma unused(arg) struct fq6_head dfq6, diq6; struct fq6_head *diq6_tmp = NULL; struct ip6q *q6; MBUFQ_INIT(&dfq6); /* for deferred frees */ MBUFQ_INIT(&diq6); /* for deferred ICMP time exceeded errors */ /* * Update coarse-grained networking timestamp (in sec.); the idea * is to piggy-back on the timeout callout to update the counter * returnable via net_uptime(). */ net_update_uptime(); lck_mtx_lock(&ip6qlock); q6 = ip6q.ip6q_next; if (q6) { while (q6 != &ip6q) { --q6->ip6q_ttl; q6 = q6->ip6q_next; if (q6->ip6q_prev->ip6q_ttl == 0) { ip6stat.ip6s_fragtimeout++; /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ /* * Avoid sending ICMPv6 Time Exceeded for fragment headers * that are marked dirty. */ diq6_tmp = (q6->ip6q_prev->ip6q_flags & IP6QF_DIRTY) ? NULL : &diq6; frag6_freef(q6->ip6q_prev, &dfq6, diq6_tmp); } } } /* * If we are over the maximum number of fragments * (due to the limit being lowered), drain off * enough to get down to the new limit. */ if (ip6_maxfragpackets >= 0) { while (frag6_nfragpackets > (unsigned)ip6_maxfragpackets && ip6q.ip6q_prev) { ip6stat.ip6s_fragoverflow++; /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ /* * Avoid sending ICMPv6 Time Exceeded for fragment headers * that are marked dirty. */ diq6_tmp = (ip6q.ip6q_prev->ip6q_flags & IP6QF_DIRTY) ? NULL : &diq6; frag6_freef(ip6q.ip6q_prev, &dfq6, diq6_tmp); } } /* re-arm the purge timer if there's work to do */ frag6_timeout_run = 0; frag6_sched_timeout(); lck_mtx_unlock(&ip6qlock); /* free fragments that need to be freed */ if (!MBUFQ_EMPTY(&dfq6)) { MBUFQ_DRAIN(&dfq6); } frag6_icmp6_timeex_error(&diq6); VERIFY(MBUFQ_EMPTY(&dfq6)); VERIFY(MBUFQ_EMPTY(&diq6)); } static void frag6_sched_timeout(void) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); if (!frag6_timeout_run && frag6_nfragpackets > 0) { frag6_timeout_run = 1; timeout(frag6_timeout, NULL, hz); } } /* * Drain off all datagram fragments. */ void frag6_drain(void) { struct fq6_head dfq6, diq6; struct fq6_head *diq6_tmp = NULL; MBUFQ_INIT(&dfq6); /* for deferred frees */ MBUFQ_INIT(&diq6); /* for deferred ICMP time exceeded errors */ lck_mtx_lock(&ip6qlock); while (ip6q.ip6q_next != &ip6q) { ip6stat.ip6s_fragdropped++; /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ /* * Avoid sending ICMPv6 Time Exceeded for fragment headers * that are marked dirty. */ diq6_tmp = (ip6q.ip6q_next->ip6q_flags & IP6QF_DIRTY) ? NULL : &diq6; frag6_freef(ip6q.ip6q_next, &dfq6, diq6_tmp); } lck_mtx_unlock(&ip6qlock); /* free fragments that need to be freed */ if (!MBUFQ_EMPTY(&dfq6)) { MBUFQ_DRAIN(&dfq6); } frag6_icmp6_timeex_error(&diq6); VERIFY(MBUFQ_EMPTY(&dfq6)); VERIFY(MBUFQ_EMPTY(&diq6)); } static struct ip6q * ip6q_alloc(void) { struct ip6q *q6; /* * See comments in ip6q_updateparams(). Keep the count separate * from frag6_nfragpackets since the latter represents the elements * already in the reassembly queues. */ if (ip6q_limit > 0 && ip6q_count > ip6q_limit) { return NULL; } q6 = kalloc_type(struct ip6q, Z_NOWAIT | Z_ZERO); if (q6 != NULL) { os_atomic_inc(&ip6q_count, relaxed); } return q6; } static void ip6q_free(struct ip6q *q6) { kfree_type(struct ip6q, q6); os_atomic_dec(&ip6q_count, relaxed); } static struct ip6asfrag * ip6af_alloc(void) { struct ip6asfrag *af6; /* * See comments in ip6q_updateparams(). Keep the count separate * from frag6_nfrags since the latter represents the elements * already in the reassembly queues. */ if (ip6af_limit > 0 && ip6af_count > ip6af_limit) { return NULL; } af6 = kalloc_type(struct ip6asfrag, Z_NOWAIT | Z_ZERO); if (af6 != NULL) { os_atomic_inc(&ip6af_count, relaxed); } return af6; } static void ip6af_free(struct ip6asfrag *af6) { kfree_type(struct ip6asfrag, af6); os_atomic_dec(&ip6af_count, relaxed); } static void ip6q_updateparams(void) { LCK_MTX_ASSERT(&ip6qlock, LCK_MTX_ASSERT_OWNED); /* * -1 for unlimited allocation. */ if (ip6_maxfragpackets < 0) { ip6q_limit = 0; } if (ip6_maxfrags < 0) { ip6af_limit = 0; } /* * Positive number for specific bound. */ if (ip6_maxfragpackets > 0) { ip6q_limit = ip6_maxfragpackets; } if (ip6_maxfrags > 0) { ip6af_limit = ip6_maxfrags; } /* * Zero specifies no further fragment queue allocation -- set the * bound very low, but rely on implementation elsewhere to actually * prevent allocation and reclaim current queues. */ if (ip6_maxfragpackets == 0) { ip6q_limit = 1; } if (ip6_maxfrags == 0) { ip6af_limit = 1; } /* * Arm the purge timer if not already and if there's work to do */ frag6_sched_timeout(); } static int sysctl_maxfragpackets SYSCTL_HANDLER_ARGS { #pragma unused(arg1, arg2) int error, i; lck_mtx_lock(&ip6qlock); i = ip6_maxfragpackets; error = sysctl_handle_int(oidp, &i, 0, req); if (error || req->newptr == USER_ADDR_NULL) { goto done; } /* impose bounds */ if (i < -1 || i > (nmbclusters / 4)) { error = EINVAL; goto done; } ip6_maxfragpackets = i; ip6q_updateparams(); done: lck_mtx_unlock(&ip6qlock); return error; } static int sysctl_maxfrags SYSCTL_HANDLER_ARGS { #pragma unused(arg1, arg2) int error, i; lck_mtx_lock(&ip6qlock); i = ip6_maxfrags; error = sysctl_handle_int(oidp, &i, 0, req); if (error || req->newptr == USER_ADDR_NULL) { goto done; } /* impose bounds */ if (i < -1 || i > (nmbclusters / 4)) { error = EINVAL; goto done; } ip6_maxfrags = i; ip6q_updateparams(); /* see if we need to arm timer */ done: lck_mtx_unlock(&ip6qlock); return error; }