Index: head/sys/netinet6/frag6.c =================================================================== --- head/sys/netinet6/frag6.c (revision 350745) +++ head/sys/netinet6/frag6.c (revision 350746) @@ -1,958 +1,949 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * 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. * * $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 /* for ECN definitions */ -#include /* for ECN definitions */ +#include /* For ECN definitions. */ +#include /* For ECN definitions. */ #ifdef MAC #include #endif -/* - * Reassembly headers are stored in hash buckets. - */ +/* 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) static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *, uint32_t bucket __unused); static void frag6_deq(struct ip6asfrag *, uint32_t bucket __unused); static void frag6_insque_head(struct ip6q *, struct ip6q *, uint32_t bucket); static void frag6_remque(struct ip6q *, uint32_t bucket); static void frag6_freef(struct ip6q *, uint32_t bucket); struct ip6qbucket { struct ip6q ip6q; struct mtx lock; int count; }; static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header"); /* 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)].ip6q) /* * 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); 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, 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_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) { struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); struct mbuf *t; /* Delete frag6 header. */ if (m->m_len >= offset + sizeof(struct ip6_frag)) { /* This is the only possible case with !PULLDOWN_TEST. */ bcopy(ip6, (char *)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, wait)) == NULL) return (ENOMEM); m_adj(t, sizeof(struct ip6_frag)); m_cat(m, t); } m->m_flags |= M_FRAGMENTED; return (0); } /* - * Free a fragment reassembly header and all - * associated datagrams. + * Free a fragment reassembly header and all associated datagrams. */ static void frag6_freef(struct ip6q *q6, uint32_t bucket) { struct ip6asfrag *af6, *down6; IP6QB_LOCK_ASSERT(bucket); 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, bucket); /* * Return ICMP time exceeded error for the 1st fragment. * Just free other fragments. */ if (af6->ip6af_off == 0) { struct ip6_hdr *ip6; - /* adjust pointer */ + /* Adjust pointer. */ ip6 = mtod(m, struct ip6_hdr *); - /* restore source and destination addresses */ + /* 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); + ICMP6_TIME_EXCEED_REASSEMBLY, 0); } else m_freem(m); + free(af6, M_FRAG6); } frag6_remque(q6, bucket); 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); } /* - * In RFC2460, fragment and reassembly rule do not agree with each other, - * in terms of next header field handling in fragment header. + * 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 the consistency. + * receiver is suggested not to check for 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. + * 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 (p21): - * The Next Header field of the last header of the Unfragmentable - * Part is obtained from the Next Header field of the first + * 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): + * 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 + * Fragment input. */ int frag6_input(struct mbuf **mp, int *offp, int proto) { struct mbuf *m = *mp, *t; struct ip6_hdr *ip6; struct ip6_frag *ip6f; struct ip6q *head, *q6; struct ip6asfrag *af6, *ip6af, *af6dwn; struct in6_ifaddr *ia; int offset = *offp, nxt, i, next; int first_frag = 0; int fragoff, frgpartlen; /* must be larger than u_int16_t */ uint32_t hashkey[(sizeof(struct in6_addr) * 2 + sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)]; uint32_t bucket, *hashkeyp; struct ifnet *dstifp; u_int8_t ecn, ecn0; #ifdef RSS struct m_tag *mtag; struct ip6_direct_ctx *ip6dc; #endif ip6 = mtod(m, struct ip6_hdr *); #ifndef PULLDOWN_TEST IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE); ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset); #else IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f)); if (ip6f == NULL) return (IPPROTO_DONE); #endif dstifp = NULL; - /* find the destination interface of the packet. */ + /* Find the destination interface of the packet. */ ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); if (ia != NULL) { dstifp = ia->ia_ifp; ifa_free(&ia->ia_ifa); } - /* jumbo payload can't contain a fragment header */ + + /* 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); return IPPROTO_DONE; } /* - * check whether fragment packet's fragment length is - * multiple of 8 octets. + * 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 */ 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); return IPPROTO_DONE; } IP6STAT_INC(ip6s_fragments); in6_ifstat_inc(dstifp, ifs6_reass_reqd); - /* offset now points to data portion */ + /* Offset now points to data portion. */ offset += sizeof(struct ip6_frag); /* * Handle "atomic" fragments (offset and m bit set to 0) upfront, - * unrelated to any reassembly (see RFC 6946 and section 4.5 of RFC - * 8200). Just skip the fragment header. + * unrelated to any reassembly. Still need to remove the frag hdr. + * See RFC 6946 and section 4.5 of RFC 8200. */ if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) { IP6STAT_INC(ip6s_atomicfrags); + /* XXX-BZ handle correctly. */ in6_ifstat_inc(dstifp, ifs6_reass_ok); *offp = offset; m->m_flags |= M_FRAGMENTED; return (ip6f->ip6f_nxt); } /* 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); return IPPROTO_DONE; } + /* 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; head = IP6QB_HEAD(bucket); IP6QB_LOCK(bucket); /* - * Enforce upper bound on number of fragments. + * 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 dropfrag; for (q6 = head->ip6q_next; q6 != head; q6 = q6->ip6q_next) 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; if (q6 == head) { - /* - * the first fragment to arrive, create a reassembly queue. - */ + + /* The first fragment to arrive, create a reassembly queue. */ first_frag = 1; /* * 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; atomic_add_int(&V_frag6_nfragpackets, 1); + + /* 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 frag6_insque_head(q6, head, bucket); - /* ip6q_nxt will be filled afterwards, from 1st fragment */ + /* 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_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */ q6->ip6q_nfrag = 0; } /* - * If it's the 1st fragment, record the length of the + * If it is the 1st fragment, record the length of the * unfragmentable part and the next header of the fragment header. */ fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK); if (fragoff == 0) { q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) - sizeof(struct ip6_frag); q6->ip6q_nxt = ip6f->ip6f_nxt; } /* * 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) { icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); IP6QB_UNLOCK(bucket); return (IPPROTO_DONE); } } else if (fragoff + frgpartlen > IPV6_MAXPACKET) { icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset - sizeof(struct ip6_frag) + offsetof(struct ip6_frag, ip6f_offlg)); IP6QB_UNLOCK(bucket); return (IPPROTO_DONE); } /* - * If it's the first fragment, do the above check for each + * If it is the first fragment, do the above check for each * fragment already stored in the reassembly queue. */ if (fragoff == 0) { for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = af6dwn) { af6dwn = af6->ip6af_down; if (q6->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. */ + /* Dequeue the fragment. */ frag6_deq(af6, bucket); free(af6, M_FRAG6); - /* adjust pointer. */ + /* 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; 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; } + /* 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. + * 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 segment which begins after this one does. - */ + /* Find a fragmented part 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; /* * If the incoming framgent overlaps some existing fragments in - * the reassembly queue, drop it, since it is dangerous to override - * existing fragments from a security point of view. - * We don't know which fragment is the bad guy - here we trust - * fragment that came in earlier, with no real reason. - * - * Note: due to changes after disabling this part, mbuf passed to - * m_adj() below now does not meet the requirement. + * 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->ip6af_up != (struct ip6asfrag *)q6) { i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen - ip6af->ip6af_off; if (i > 0) { free(ip6af, M_FRAG6); goto dropfrag; } } if (af6 != (struct ip6asfrag *)q6) { i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off; if (i > 0) { free(ip6af, M_FRAG6); goto dropfrag; } } insert: #ifdef MAC if (!first_frag) 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. + * 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. */ frag6_enq(ip6af, af6->ip6af_up, bucket); atomic_add_int(&frag6_nfrags, 1); q6->ip6q_nfrag++; next = 0; for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6; af6 = af6->ip6af_down) { if (af6->ip6af_off != next) { if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); return IPPROTO_DONE; } next += af6->ip6af_frglen; } if (af6->ip6af_up->ip6af_mff) { if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) { IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag); frag6_freef(q6, bucket); } IP6QB_UNLOCK(bucket); return IPPROTO_DONE; } - /* - * Reassembly is complete; concatenate fragments. - */ + /* Reassembly is complete; concatenate fragments. */ ip6af = q6->ip6q_down; t = m = IP6_REASS_MBUF(ip6af); af6 = ip6af->ip6af_down; frag6_deq(ip6af, bucket); while (af6 != (struct ip6asfrag *)q6) { m->m_pkthdr.csum_flags &= IP6_REASS_MBUF(af6)->m_pkthdr.csum_flags; m->m_pkthdr.csum_data += IP6_REASS_MBUF(af6)->m_pkthdr.csum_data; af6dwn = af6->ip6af_down; frag6_deq(af6, bucket); while (t->m_next) t = t->m_next; m_adj(IP6_REASS_MBUF(af6), af6->ip6af_offset); m_demote_pkthdr(IP6_REASS_MBUF(af6)); m_cat(t, IP6_REASS_MBUF(af6)); free(af6, M_FRAG6); af6 = af6dwn; } 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 */ + /* 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)next + offset - sizeof(struct ip6_hdr)); if (q6->ip6q_ecn == IPTOS_ECN_CE) ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20); nxt = q6->ip6q_nxt; if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) { frag6_remque(q6, bucket); 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); goto dropfrag; } - /* - * Store NXT to the original. - */ + /* Set nxt(-hdr field value) to the original value. */ m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t), (caddr_t)&nxt); frag6_remque(q6, bucket); atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag); #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? */ int plen = 0; for (t = m; t; t = t->m_next) plen += t->m_len; m->m_pkthdr.len = plen; } #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. - */ + /* Queue/dispatch for reprocessing. */ netisr_dispatch(NETISR_IPV6_DIRECT, m); return IPPROTO_DONE; #endif - /* - * Tell launch routine the next header - */ - + /* Tell launch routine the next header. */ *mp = m; *offp = offset; return nxt; dropfrag: IP6QB_UNLOCK(bucket); in6_ifstat_inc(dstifp, ifs6_reass_fail); IP6STAT_INC(ip6s_fragdropped); m_freem(m); return IPPROTO_DONE; } /* * IPv6 reassembling timer processing; - * if a timer expires on a reassembly - * queue, discard it. + * if a timer expires on a reassembly queue, discard it. */ void frag6_slowtimo(void) { VNET_ITERATOR_DECL(vnet_iter); struct ip6q *head, *q6; 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); q6 = head->ip6q_next; if (q6 == NULL) { /* * XXXJTL: This should never happen. This * should turn into an assertion. */ IP6QB_UNLOCK(bucket); continue; } while (q6 != head) { --q6->ip6q_ttl; q6 = q6->ip6q_next; if (q6->ip6q_prev->ip6q_ttl == 0) { IP6STAT_ADD(ip6s_fragtimeout, q6->ip6q_prev->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(q6->ip6q_prev, 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 don't enforce a limit when maxfragpackets + * 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)) && head->ip6q_prev != head) { IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_prev->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(head->ip6q_prev, 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); head = IP6QB_HEAD(bucket); if (head->ip6q_prev != head) { IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_prev->ip6q_nfrag); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(head->ip6q_prev, 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) { struct ip6q *q6; uint32_t bucket; V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS; frag6_set_bucketsize(); for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { q6 = IP6QB_HEAD(bucket); q6->ip6q_next = q6->ip6q_prev = q6; mtx_init(&V_ip6qb[bucket].lock, "ip6qlock", NULL, MTX_DEF); V_ip6qb[bucket].count = 0; } V_ip6qb_hashseed = arc4random(); V_ip6_maxfragsperpacket = 64; 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. */ void frag6_drain(void) { VNET_ITERATOR_DECL(vnet_iter); struct ip6q *head; uint32_t bucket; VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) { if (IP6QB_TRYLOCK(bucket) == 0) continue; head = IP6QB_HEAD(bucket); while (head->ip6q_next != head) { IP6STAT_INC(ip6s_fragdropped); /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */ frag6_freef(head->ip6q_next, bucket); } IP6QB_UNLOCK(bucket); } CURVNET_RESTORE(); } VNET_LIST_RUNLOCK_NOSLEEP(); } /* * Put an ip fragment on a reassembly chain. * Like insque, but pointers in middle of structure. */ static void frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6, uint32_t bucket __unused) { IP6QB_LOCK_ASSERT(bucket); 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. */ static void frag6_deq(struct ip6asfrag *af6, uint32_t bucket __unused) { IP6QB_LOCK_ASSERT(bucket); af6->ip6af_up->ip6af_down = af6->ip6af_down; af6->ip6af_down->ip6af_up = af6->ip6af_up; } static void frag6_insque_head(struct ip6q *new, struct ip6q *old, uint32_t bucket) { IP6QB_LOCK_ASSERT(bucket); KASSERT(IP6QB_HEAD(bucket) == old, ("%s: attempt to insert at head of wrong bucket" " (bucket=%u, old=%p)", __func__, bucket, old)); new->ip6q_prev = old; new->ip6q_next = old->ip6q_next; old->ip6q_next->ip6q_prev= new; old->ip6q_next = new; V_ip6qb[bucket].count++; } static void frag6_remque(struct ip6q *p6, uint32_t bucket) { IP6QB_LOCK_ASSERT(bucket); p6->ip6q_prev->ip6q_next = p6->ip6q_next; p6->ip6q_next->ip6q_prev = p6->ip6q_prev; V_ip6qb[bucket].count--; }