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- /*-
- * 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 <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include "opt_rss.h"
- #include <sys/param.h>
- #include <sys/systm.h>
- #include <sys/domain.h>
- #include <sys/eventhandler.h>
- #include <sys/hash.h>
- #include <sys/kernel.h>
- #include <sys/malloc.h>
- #include <sys/mbuf.h>
- #include <sys/protosw.h>
- #include <sys/queue.h>
- #include <sys/socket.h>
- #include <sys/sysctl.h>
- #include <sys/syslog.h>
- #include <net/if.h>
- #include <net/if_var.h>
- #include <net/netisr.h>
- #include <net/route.h>
- #include <net/vnet.h>
- #include <netinet/in.h>
- #include <netinet/in_var.h>
- #include <netinet/ip6.h>
- #include <netinet6/ip6_var.h>
- #include <netinet/icmp6.h>
- #include <netinet/in_systm.h> /* For ECN definitions. */
- #include <netinet/ip.h> /* For ECN definitions. */
- #ifdef MAC
- #include <security/mac/mac_framework.h>
- #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 */);
- if (ia6 != NULL) {
- dstifp = ia6->ia_ifp;
- ifa_free(&ia6->ia_ifa);
- }
- /* 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
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