/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * All rights reserved. * Copyright (c) 2019 Netflix, Inc. * * 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. * * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ */ #include __FBSDID("$FreeBSD$"); #include "opt_rss.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 /* For ECN definitions. */ #include /* For ECN definitions. */ #ifdef MAC #include #endif /* * A "big picture" of how IPv6 fragment queues are all linked together. * * struct ip6qbucket ip6qb[...]; hashed buckets * |||||||| * | * +--- TAILQ(struct ip6q, packets) *q6; tailq entries holding * |||||||| fragmented packets * | (1 per original packet) * | * +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6; tailq entries of IPv6 * | *ip6af;fragment packets * | for one original packet * + *mbuf */ /* Reassembly headers are stored in hash buckets. */ #define IP6REASS_NHASH_LOG2 10 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2) #define IP6REASS_HMASK (IP6REASS_NHASH - 1) TAILQ_HEAD(ip6qhead, ip6q); struct ip6qbucket { struct ip6qhead packets; struct mtx lock; int count; }; struct ip6asfrag { TAILQ_ENTRY(ip6asfrag) ip6af_tq; 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. */ bool ip6af_mff; /* More fragment bit in frag off. */ }; static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header"); #ifdef VIMAGE /* A flag to indicate if IPv6 fragmentation is initialized. */ VNET_DEFINE_STATIC(bool, frag6_on); #define V_frag6_on VNET(frag6_on) #endif /* System wide (global) maximum and count of packets in reassembly queues. */ static int ip6_maxfrags; static volatile u_int frag6_nfrags = 0; /* Maximum and current packets in per-VNET reassembly queue. */ VNET_DEFINE_STATIC(int, ip6_maxfragpackets); VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets); #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) #define V_frag6_nfragpackets VNET(frag6_nfragpackets) /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */ VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize); VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket); #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize) #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket) /* Per-VNET reassembly queue buckets. */ VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]); VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed); #define V_ip6qb VNET(ip6qb) #define V_ip6qb_hashseed VNET(ip6qb_hashseed) #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock) #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock) #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED) #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock) #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].packets) /* * By default, limit the number of IP6 fragments across all reassembly * queues to 1/32 of the total number of mbuf clusters. * * Limit the total number of reassembly queues per VNET to the * IP6 fragment limit, but ensure the limit will not allow any bucket * to grow above 100 items. (The bucket limit is * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct * multiplier to reach a 100-item limit.) * The 100-item limit was chosen as brief testing seems to show that * this produces "reasonable" performance on some subset of systems * under DoS attack. */ #define IP6_MAXFRAGS (nmbclusters / 32) #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50)) /* * Sysctls and helper function. */ SYSCTL_DECL(_net_inet6_ip6); SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags, CTLFLAG_RD, __DEVOLATILE(u_int *, &frag6_nfrags), 0, "Global number of IPv6 fragments across all reassembly queues."); static void frag6_set_bucketsize(void) { int i; if ((i = V_ip6_maxfragpackets) > 0) V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1); } SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags, CTLFLAG_RW, &ip6_maxfrags, 0, "Maximum allowed number of outstanding IPv6 packet fragments. " "A value of 0 means no fragmented packets will be accepted, while a " "a value of -1 means no limit"); static int sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS) { int error, val; val = V_ip6_maxfragpackets; error = sysctl_handle_int(oidp, &val, 0, req); if (error != 0 || !req->newptr) return (error); V_ip6_maxfragpackets = val; frag6_set_bucketsize(); return (0); } SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets, CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0, sysctl_ip6_maxfragpackets, "I", "Default maximum number of outstanding fragmented IPv6 packets. " "A value of 0 means no fragmented packets will be accepted, while a " "a value of -1 means no limit"); SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets, CTLFLAG_VNET | CTLFLAG_RD, __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0, "Per-VNET number of IPv6 fragments across all reassembly queues."); SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0, "Maximum allowed number of fragments per packet"); SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0, "Maximum number of reassembly queues per hash bucket"); /* * Remove the IPv6 fragmentation header from the mbuf. */ int ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused) { struct ip6_hdr *ip6; KASSERT(m->m_len >= offset + sizeof(struct ip6_frag), ("%s: ext headers not contigous in mbuf %p m_len %d >= " "offset %d + %zu\n", __func__, m, m->m_len, offset, sizeof(struct ip6_frag))); /* Delete frag6 header. */ ip6 = mtod(m, struct ip6_hdr *); bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset); m->m_data += sizeof(struct ip6_frag); m->m_len -= sizeof(struct ip6_frag); m->m_flags |= M_FRAGMENTED; return (0); } /* * Free a fragment reassembly header and all associated datagrams. */ static void frag6_freef(struct ip6q *q6, uint32_t bucket) { struct ip6_hdr *ip6; struct ip6asfrag *af6; struct mbuf *m; IP6QB_LOCK_ASSERT(bucket); while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { m = af6->ip6af_m; TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); /* * Return ICMP time exceeded error for the 1st fragment. * Just free other fragments. */ if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) { /* 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; icmp6_error(m, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_REASSEMBLY, 0); } else m_freem(m); free(af6, M_FRAG6); } TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq); V_ip6qb[bucket].count--; atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); #ifdef MAC mac_ip6q_destroy(q6); #endif free(q6, M_FRAG6); atomic_subtract_int(&V_frag6_nfragpackets, 1); } /* * Drain off all datagram fragments belonging to * the given network interface. */ static void frag6_cleanup(void *arg __unused, struct ifnet *ifp) { struct ip6qhead *head; struct ip6q *q6; struct ip6asfrag *af6; uint32_t bucket; KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); CURVNET_SET_QUIET(ifp->if_vnet); #ifdef VIMAGE /* * Skip processing if IPv6 reassembly is not initialised or * torn down by frag6_destroy(). */ if (!V_frag6_on) { CURVNET_RESTORE(); return; } #endif for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { IP6QB_LOCK(bucket); head = IP6QB_HEAD(bucket); /* Scan fragment list. */ TAILQ_FOREACH(q6, head, ip6q_tq) { TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { /* Clear no longer valid rcvif pointer. */ if (af6->ip6af_m->m_pkthdr.rcvif == ifp) af6->ip6af_m->m_pkthdr.rcvif = NULL; } } IP6QB_UNLOCK(bucket); } CURVNET_RESTORE(); } EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0); /* * Like in RFC2460, in RFC8200, fragment and reassembly rules 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 for consistency. * * Fragment rules (p18,p19): * (2) A Fragment header containing: * The Next Header value that identifies the first header * after the Per-Fragment headers of the original packet. * -> next header field is same for all fragments * * Reassembly rule (p20): * The Next Header field of the last header of the Per-Fragment * headers 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 - no one is going to * send different fragment with different next header field. * * Additional note (p22) [not an error]: * 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) { struct mbuf *m, *t; struct ip6_hdr *ip6; struct ip6_frag *ip6f; struct ip6qhead *head; struct ip6q *q6; struct ip6asfrag *af6, *ip6af, *af6tmp; struct in6_ifaddr *ia6; struct ifnet *dstifp, *srcifp; uint32_t hashkey[(sizeof(struct in6_addr) * 2 + sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; uint32_t bucket, *hashkeyp; int fragoff, frgpartlen; /* Must be larger than uint16_t. */ int nxt, offset, plen; uint8_t ecn, ecn0; bool only_frag; #ifdef RSS struct ip6_direct_ctx *ip6dc; struct m_tag *mtag; #endif m = *mp; offset = *offp; M_ASSERTPKTHDR(m); if (m->m_len < offset + sizeof(struct ip6_frag)) { m = m_pullup(m, offset + sizeof(struct ip6_frag)); if (m == NULL) { IP6STAT_INC(ip6s_exthdrtoolong); *mp = NULL; return (IPPROTO_DONE); } } ip6 = mtod(m, struct ip6_hdr *); dstifp = NULL; /* Find the destination interface of the packet. */ ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); if (ia6 != NULL) dstifp = ia6->ia_ifp; /* Jumbo payload cannot 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); *mp = NULL; return (IPPROTO_DONE); } /* * Check whether fragment packet's fragment length is a * multiple of 8 octets (unless it is the last one). * sizeof(struct ip6_frag) == 8 * sizeof(struct ip6_hdr) = 40 */ ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); 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); *mp = NULL; return (IPPROTO_DONE); } IP6STAT_INC(ip6s_fragments); in6_ifstat_inc(dstifp, ifs6_reass_reqd); /* * Handle "atomic" fragments (offset and m bit set to 0) upfront, * unrelated to any reassembly. We need to remove the frag hdr * which is ugly. * See RFC 6946 and section 4.5 of RFC 8200. */ if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { IP6STAT_INC(ip6s_atomicfrags); nxt = ip6f->ip6f_nxt; /* * Set nxt(-hdr field value) to the original value. * We cannot just set ip6->ip6_nxt as there might be * an unfragmentable part with extension headers and * we must update the last one. */ m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), (caddr_t)&nxt); ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - sizeof(struct ip6_frag)); if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) goto dropfrag2; m->m_pkthdr.len -= sizeof(struct ip6_frag); in6_ifstat_inc(dstifp, ifs6_reass_ok); *mp = m; return (nxt); } /* Offset now points to data portion. */ offset += sizeof(struct ip6_frag); /* Get fragment length and discard 0-byte fragments. */ frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset; if (frgpartlen == 0) { icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offsetof(struct ip6_hdr, ip6_plen)); in6_ifstat_inc(dstifp, ifs6_reass_fail); IP6STAT_INC(ip6s_fragdropped); *mp = NULL; return (IPPROTO_DONE); } /* * Enforce upper bound on number of fragments for the entire system. * If maxfrag is 0, never accept fragments. * If maxfrag is -1, accept all fragments without limitation. */ if (ip6_maxfrags < 0) ; else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags) goto dropfrag2; /* * Validate that a full header chain to the ULP is present in the * packet containing the first fragment as per RFC RFC7112 and * RFC 8200 pages 18,19: * The first fragment packet is composed of: * (3) Extension headers, if any, and the Upper-Layer header. These * headers must be in the first fragment. ... */ fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); /* XXX TODO. thj has D16851 open for this. */ /* Send ICMPv6 4,3 in case of violation. */ /* Store receive network interface pointer for later. */ srcifp = m->m_pkthdr.rcvif; /* Generate a hash value for fragment bucket selection. */ hashkeyp = hashkey; memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr)); hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr)); hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp); *hashkeyp = ip6f->ip6f_ident; bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed); bucket &= IP6REASS_HMASK; IP6QB_LOCK(bucket); head = IP6QB_HEAD(bucket); TAILQ_FOREACH(q6, head, ip6q_tq) if (ip6f->ip6f_ident == q6->ip6q_ident && IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) && IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst) #ifdef MAC && mac_ip6q_match(m, q6) #endif ) break; only_frag = false; if (q6 == NULL) { /* A first fragment to arrive creates a reassembly queue. */ only_frag = true; /* * Enforce upper bound on number of fragmented packets * for which we attempt reassembly; * If maxfragpackets is 0, never accept fragments. * If maxfragpackets is -1, accept all fragments without * limitation. */ if (V_ip6_maxfragpackets < 0) ; else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize || atomic_load_int(&V_frag6_nfragpackets) >= (u_int)V_ip6_maxfragpackets) goto dropfrag; /* Allocate IPv6 fragement packet queue entry. */ q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6, M_NOWAIT | M_ZERO); if (q6 == NULL) goto dropfrag; #ifdef MAC if (mac_ip6q_init(q6, M_NOWAIT) != 0) { free(q6, M_FRAG6); goto dropfrag; } mac_ip6q_create(m, q6); #endif atomic_add_int(&V_frag6_nfragpackets, 1); /* ip6q_nxt will be filled afterwards, from 1st fragment. */ TAILQ_INIT(&q6->ip6q_frags); 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_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ /* Add the fragemented packet to the bucket. */ TAILQ_INSERT_HEAD(head, q6, ip6q_tq); V_ip6qb[bucket].count++; } /* * If it is the 1st fragment, record the length of the * unfragmentable part and the next header of the fragment header. * Assume the first 1st 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. */ if (fragoff == 0 && q6->ip6q_unfrglen == -1) { q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - sizeof(struct ip6_frag); q6->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. */ if (q6->ip6q_unfrglen >= 0) { /* The 1st fragment has already arrived. */ if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) { if (only_frag) { TAILQ_REMOVE(head, q6, ip6q_tq); V_ip6qb[bucket].count--; atomic_subtract_int(&V_frag6_nfragpackets, 1); #ifdef MAC mac_ip6q_destroy(q6); #endif free(q6, M_FRAG6); } IP6QB_UNLOCK(bucket); icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); *mp = NULL; return (IPPROTO_DONE); } } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { if (only_frag) { TAILQ_REMOVE(head, q6, ip6q_tq); V_ip6qb[bucket].count--; atomic_subtract_int(&V_frag6_nfragpackets, 1); #ifdef MAC mac_ip6q_destroy(q6); #endif free(q6, M_FRAG6); } IP6QB_UNLOCK(bucket); icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); *mp = NULL; return (IPPROTO_DONE); } /* * If it is the first fragment, do the above check for each * fragment already stored in the reassembly queue. */ if (fragoff == 0 && !only_frag) { TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) { if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen > IPV6_MAXPACKET) { struct ip6_hdr *ip6err; struct mbuf *merr; int erroff; merr = af6->ip6af_m; erroff = af6->ip6af_offset; /* Dequeue the fragment. */ TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); q6->ip6q_nfrag--; atomic_subtract_int(&frag6_nfrags, 1); free(af6, M_FRAG6); /* Set a valid receive interface pointer. */ merr->m_pkthdr.rcvif = srcifp; /* 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; icmp6_error(merr, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, erroff - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); } } } /* Allocate an IPv6 fragement queue entry for this fragmented part. */ ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6, M_NOWAIT | M_ZERO); if (ip6af == NULL) goto dropfrag; ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false; ip6af->ip6af_off = fragoff; ip6af->ip6af_frglen = frgpartlen; ip6af->ip6af_offset = offset; ip6af->ip6af_m = m; if (only_frag) { /* * Do a manual insert rather than a hard-to-understand cast * to a different type relying on data structure order to work. */ TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq); goto postinsert; } /* Do duplicate, condition, and boundry checks. */ /* * 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) { free(ip6af, M_FRAG6); goto dropfrag; } if (ecn0 != IPTOS_ECN_CE) q6->ip6q_ecn = IPTOS_ECN_CE; } if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) { free(ip6af, M_FRAG6); goto dropfrag; } /* Find a fragmented part which begins after this one does. */ TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) if (af6->ip6af_off > ip6af->ip6af_off) break; /* * If the incoming framgent overlaps some existing fragments in * the reassembly queue, drop both the new fragment and the * entire reassembly queue. However, if the new fragment * is an exact duplicate of an existing fragment, only silently * drop the existing fragment and leave the fragmentation queue * unchanged, as allowed by the RFC. (RFC 8200, 4.5) */ if (af6 != NULL) af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq); else af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); if (af6tmp != NULL) { if (af6tmp->ip6af_off + af6tmp->ip6af_frglen - ip6af->ip6af_off > 0) { if (af6tmp->ip6af_off != ip6af->ip6af_off || af6tmp->ip6af_frglen != ip6af->ip6af_frglen) frag6_freef(q6, bucket); free(ip6af, M_FRAG6); goto dropfrag; } } if (af6 != NULL) { if (ip6af->ip6af_off + ip6af->ip6af_frglen - af6->ip6af_off > 0) { if (af6->ip6af_off != ip6af->ip6af_off || af6->ip6af_frglen != ip6af->ip6af_frglen) frag6_freef(q6, bucket); free(ip6af, M_FRAG6); goto dropfrag; } } #ifdef MAC mac_ip6q_update(m, q6); #endif /* * Stick new segment in its place; check for complete reassembly. * If not complete, check fragment limit. Move to front of packet * queue, as we are the most recently active fragmented packet. */ if (af6 != NULL) TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq); else TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq); postinsert: atomic_add_int(&frag6_nfrags, 1); q6->ip6q_nfrag++; plen = 0; TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) { if (af6->ip6af_off != plen) { if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); *mp = NULL; return (IPPROTO_DONE); } plen += af6->ip6af_frglen; } af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead); if (af6->ip6af_mff) { if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); *mp = NULL; return (IPPROTO_DONE); } /* Reassembly is complete; concatenate fragments. */ ip6af = TAILQ_FIRST(&q6->ip6q_frags); t = m = ip6af->ip6af_m; TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq); while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) { m->m_pkthdr.csum_flags &= af6->ip6af_m->m_pkthdr.csum_flags; m->m_pkthdr.csum_data += af6->ip6af_m->m_pkthdr.csum_data; TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq); t = m_last(t); m_adj(af6->ip6af_m, af6->ip6af_offset); m_demote_pkthdr(af6->ip6af_m); m_cat(t, af6->ip6af_m); free(af6, M_FRAG6); } while (m->m_pkthdr.csum_data & 0xffff0000) m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16); /* Adjust offset to point where the original next header starts. */ offset = ip6af->ip6af_offset - sizeof(struct ip6_frag); free(ip6af, M_FRAG6); ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr)); if (q6->ip6q_ecn == IPTOS_ECN_CE) ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); nxt = q6->ip6q_nxt; TAILQ_REMOVE(head, q6, ip6q_tq); V_ip6qb[bucket].count--; atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); ip6_deletefraghdr(m, offset, M_NOWAIT); /* Set nxt(-hdr field value) to the original value. */ m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), (caddr_t)&nxt); #ifdef MAC mac_ip6q_reassemble(q6, m); mac_ip6q_destroy(q6); #endif free(q6, M_FRAG6); atomic_subtract_int(&V_frag6_nfragpackets, 1); if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */ plen = 0; for (t = m; t; t = t->m_next) plen += t->m_len; m->m_pkthdr.len = plen; /* Set a valid receive interface pointer. */ m->m_pkthdr.rcvif = srcifp; } #ifdef RSS mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc), M_NOWAIT); if (mtag == NULL) goto dropfrag; ip6dc = (struct ip6_direct_ctx *)(mtag + 1); ip6dc->ip6dc_nxt = nxt; ip6dc->ip6dc_off = offset; m_tag_prepend(m, mtag); #endif IP6QB_UNLOCK(bucket); IP6STAT_INC(ip6s_reassembled); in6_ifstat_inc(dstifp, ifs6_reass_ok); #ifdef RSS /* Queue/dispatch for reprocessing. */ netisr_dispatch(NETISR_IPV6_DIRECT, m); *mp = NULL; return (IPPROTO_DONE); #endif /* Tell launch routine the next header. */ *mp = m; *offp = offset; return (nxt); dropfrag: IP6QB_UNLOCK(bucket); dropfrag2: in6_ifstat_inc(dstifp, ifs6_reass_fail); IP6STAT_INC(ip6s_fragdropped); m_freem(m); *mp = NULL; return (IPPROTO_DONE); } /* * IPv6 reassembling timer processing; * if a timer expires on a reassembly queue, discard it. */ void frag6_slowtimo(void) { VNET_ITERATOR_DECL(vnet_iter); struct ip6qhead *head; struct ip6q *q6, *q6tmp; uint32_t bucket; VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { IP6QB_LOCK(bucket); head = IP6QB_HEAD(bucket); TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp) if (--q6->ip6q_ttl == 0) { IP6STAT_ADD(ip6s_fragtimeout, q6->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(q6, bucket); } /* * 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. * Note that we drain all reassembly queues if * maxfragpackets is 0 (fragmentation is disabled), * and do not enforce a limit when maxfragpackets * is negative. */ while ((V_ip6_maxfragpackets == 0 || (V_ip6_maxfragpackets > 0 && V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) && (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) { IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); } /* * If we are still over the maximum number of fragmented * packets, drain off enough to get down to the new limit. */ bucket = 0; while (V_ip6_maxfragpackets >= 0 && atomic_load_int(&V_frag6_nfragpackets) > (u_int)V_ip6_maxfragpackets) { IP6QB_LOCK(bucket); q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead); if (q6 != NULL) { IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); bucket = (bucket + 1) % IP6REASS_NHASH; } CURVNET_RESTORE(); } VNET_LIST_RUNLOCK_NOSLEEP(); } /* * Eventhandler to adjust limits in case nmbclusters change. */ static void frag6_change(void *tag) { VNET_ITERATOR_DECL(vnet_iter); ip6_maxfrags = IP6_MAXFRAGS; VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; frag6_set_bucketsize(); CURVNET_RESTORE(); } VNET_LIST_RUNLOCK_NOSLEEP(); } /* * Initialise reassembly queue and fragment identifier. */ void frag6_init(void) { uint32_t bucket; V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; frag6_set_bucketsize(); for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { TAILQ_INIT(IP6QB_HEAD(bucket)); mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF); V_ip6qb[bucket].count = 0; } V_ip6qb_hashseed = arc4random(); V_ip6_maxfragsperpacket = 64; #ifdef VIMAGE V_frag6_on = true; #endif if (!IS_DEFAULT_VNET(curvnet)) return; ip6_maxfrags = IP6_MAXFRAGS; EVENTHANDLER_REGISTER(nmbclusters_change, frag6_change, NULL, EVENTHANDLER_PRI_ANY); } /* * Drain off all datagram fragments. */ static void frag6_drain_one(void) { struct ip6q *q6; uint32_t bucket; for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { IP6QB_LOCK(bucket); while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) { IP6STAT_INC(ip6s_fragdropped); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); } } void frag6_drain(void) { VNET_ITERATOR_DECL(vnet_iter); VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); frag6_drain_one(); CURVNET_RESTORE(); } VNET_LIST_RUNLOCK_NOSLEEP(); } #ifdef VIMAGE /* * Clear up IPv6 reassembly structures. */ void frag6_destroy(void) { uint32_t bucket; frag6_drain_one(); V_frag6_on = false; for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { KASSERT(V_ip6qb[bucket].count == 0, ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__, bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count)); mtx_destroy(&V_ip6qb[bucket].lock); } } #endif