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freebsd-dev/sys/netinet6/frag6.c
Kristof Provost 505e91f500 frag6: Fix fragment reassembly 
r337776 started hashing the fragments into buckets for faster lookup.

The hashkey is larger than intended. This results in random stack data being
included in the hashed data, which in turn means that fragments of the same
packet might end up in different buckets, causing the reassembly to fail.

Set the correct size for hashkey.

PR:		231045
Approved by:	re (kib)
MFC after:	3 days
2018-08-31 08:37:15 +00:00

964 lines
26 KiB
C
Raw Blame History

/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_rss.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/hash.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/eventhandler.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <machine/atomic.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 */
#include <security/mac/mac_framework.h>
/*
* 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;
};
VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets);
volatile u_int frag6_nfrags = 0;
VNET_DEFINE_STATIC(struct ip6qbucket, ip6q[IP6REASS_NHASH]);
VNET_DEFINE_STATIC(uint32_t, ip6q_hashseed);
#define V_frag6_nfragpackets VNET(frag6_nfragpackets)
#define V_ip6q VNET(ip6q)
#define V_ip6q_hashseed VNET(ip6q_hashseed)
#define IP6Q_LOCK(i) mtx_lock(&V_ip6q[(i)].lock)
#define IP6Q_TRYLOCK(i) mtx_trylock(&V_ip6q[(i)].lock)
#define IP6Q_LOCK_ASSERT(i) mtx_assert(&V_ip6q[(i)].lock, MA_OWNED)
#define IP6Q_UNLOCK(i) mtx_unlock(&V_ip6q[(i)].lock)
#define IP6Q_HEAD(i) (&V_ip6q[(i)].ip6q)
static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
/*
* 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))
/*
* Initialise reassembly queue and fragment identifier.
*/
void
frag6_set_bucketsize()
{
int i;
if ((i = V_ip6_maxfragpackets) > 0)
V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1);
}
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();
}
void
frag6_init(void)
{
struct ip6q *q6;
int i;
V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
frag6_set_bucketsize();
for (i = 0; i < IP6REASS_NHASH; i++) {
q6 = IP6Q_HEAD(i);
q6->ip6q_next = q6->ip6q_prev = q6;
mtx_init(&V_ip6q[i].lock, "ip6qlock", NULL, MTX_DEF);
V_ip6q[i].count = 0;
}
V_ip6q_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);
}
/*
* 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 - no one 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)
{
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 hash, *hashkeyp;
struct ifnet *dstifp;
u_int8_t ecn, ecn0;
#ifdef RSS
struct m_tag *mtag;
struct ip6_direct_ctx *ip6dc;
#endif
#if 0
char ip6buf[INET6_ADDRSTRLEN];
#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. */
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 */
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.
* 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 += 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) {
/* XXX-BZ we want dedicated counters for this. */
IP6STAT_INC(ip6s_reassembled);
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;
}
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;
hash = jenkins_hash32(hashkey, nitems(hashkey), V_ip6q_hashseed);
hash &= IP6REASS_HMASK;
head = IP6Q_HEAD(hash);
IP6Q_LOCK(hash);
/*
* Enforce upper bound on number of fragments.
* 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.
*/
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_ip6q[hash].count >= V_ip6_maxfragbucketsize ||
atomic_load_int(&V_frag6_nfragpackets) >=
(u_int)V_ip6_maxfragpackets)
goto dropfrag;
atomic_add_int(&V_frag6_nfragpackets, 1);
q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
M_NOWAIT);
if (q6 == NULL)
goto dropfrag;
bzero(q6, sizeof(*q6));
#ifdef MAC
if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
free(q6, M_FTABLE);
goto dropfrag;
}
mac_ip6q_create(m, q6);
#endif
frag6_insque_head(q6, head, hash);
/* 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
* 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));
IP6Q_UNLOCK(hash);
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));
IP6Q_UNLOCK(hash);
return (IPPROTO_DONE);
}
/*
* If it's 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. */
frag6_deq(af6, hash);
free(af6, M_FTABLE);
/* 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));
}
}
}
ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
M_NOWAIT);
if (ip6af == NULL)
goto dropfrag;
bzero(ip6af, sizeof(*ip6af));
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) {
free(ip6af, M_FTABLE);
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_FTABLE);
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;
#if 0
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us.
*/
if (af6->ip6af_up != (struct ip6asfrag *)q6) {
i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
- ip6af->ip6af_off;
if (i > 0) {
if (i >= ip6af->ip6af_frglen)
goto dropfrag;
m_adj(IP6_REASS_MBUF(ip6af), i);
ip6af->ip6af_off += i;
ip6af->ip6af_frglen -= i;
}
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
while (af6 != (struct ip6asfrag *)q6 &&
ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
if (i < af6->ip6af_frglen) {
af6->ip6af_frglen -= i;
af6->ip6af_off += i;
m_adj(IP6_REASS_MBUF(af6), i);
break;
}
af6 = af6->ip6af_down;
m_freem(IP6_REASS_MBUF(af6->ip6af_up));
frag6_deq(af6->ip6af_up, hash);
}
#else
/*
* 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.
*/
if (af6->ip6af_up != (struct ip6asfrag *)q6) {
i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
- ip6af->ip6af_off;
if (i > 0) {
#if 0 /* suppress the noisy log */
log(LOG_ERR, "%d bytes of a fragment from %s "
"overlaps the previous fragment\n",
i, ip6_sprintf(ip6buf, &q6->ip6q_src));
#endif
free(ip6af, M_FTABLE);
goto dropfrag;
}
}
if (af6 != (struct ip6asfrag *)q6) {
i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
if (i > 0) {
#if 0 /* suppress the noisy log */
log(LOG_ERR, "%d bytes of a fragment from %s "
"overlaps the succeeding fragment",
i, ip6_sprintf(ip6buf, &q6->ip6q_src));
#endif
free(ip6af, M_FTABLE);
goto dropfrag;
}
}
#endif
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.
*/
frag6_enq(ip6af, af6->ip6af_up, hash);
atomic_add_int(&frag6_nfrags, 1);
q6->ip6q_nfrag++;
#if 0 /* xxx */
if (q6 != head->ip6q_next) {
frag6_remque(q6, hash);
frag6_insque_head(q6, head, hash);
}
#endif
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_INC(ip6s_fragdropped);
frag6_freef(q6, hash);
}
IP6Q_UNLOCK(hash);
return IPPROTO_DONE;
}
next += af6->ip6af_frglen;
}
if (af6->ip6af_up->ip6af_mff) {
if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
IP6STAT_INC(ip6s_fragdropped);
frag6_freef(q6, hash);
}
IP6Q_UNLOCK(hash);
return IPPROTO_DONE;
}
/*
* Reassembly is complete; concatenate fragments.
*/
ip6af = q6->ip6q_down;
t = m = IP6_REASS_MBUF(ip6af);
af6 = ip6af->ip6af_down;
frag6_deq(ip6af, hash);
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, hash);
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_FTABLE);
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 */
offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
free(ip6af, M_FTABLE);
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;
#ifdef notyet
*q6->ip6q_nxtp = (u_char)(nxt & 0xff);
#endif
if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0) {
frag6_remque(q6, hash);
atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
#ifdef MAC
mac_ip6q_destroy(q6);
#endif
free(q6, M_FTABLE);
atomic_subtract_int(&V_frag6_nfragpackets, 1);
goto dropfrag;
}
/*
* Store NXT to the original.
*/
m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
(caddr_t)&nxt);
frag6_remque(q6, hash);
atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
#ifdef MAC
mac_ip6q_reassemble(q6, m);
mac_ip6q_destroy(q6);
#endif
free(q6, M_FTABLE);
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
IP6Q_UNLOCK(hash);
IP6STAT_INC(ip6s_reassembled);
in6_ifstat_inc(dstifp, ifs6_reass_ok);
#ifdef RSS
/*
* Queue/dispatch for reprocessing.
*/
netisr_dispatch(NETISR_IPV6_DIRECT, m);
return IPPROTO_DONE;
#endif
/*
* Tell launch routine the next header
*/
*mp = m;
*offp = offset;
return nxt;
dropfrag:
IP6Q_UNLOCK(hash);
in6_ifstat_inc(dstifp, ifs6_reass_fail);
IP6STAT_INC(ip6s_fragdropped);
m_freem(m);
return IPPROTO_DONE;
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void
frag6_freef(struct ip6q *q6, uint32_t bucket)
{
struct ip6asfrag *af6, *down6;
IP6Q_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 */
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_FTABLE);
}
frag6_remque(q6, bucket);
atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
#ifdef MAC
mac_ip6q_destroy(q6);
#endif
free(q6, M_FTABLE);
atomic_subtract_int(&V_frag6_nfragpackets, 1);
}
/*
* 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)
{
IP6Q_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)
{
IP6Q_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)
{
IP6Q_LOCK_ASSERT(bucket);
KASSERT(IP6Q_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_ip6q[bucket].count++;
}
static void
frag6_remque(struct ip6q *p6, uint32_t bucket)
{
IP6Q_LOCK_ASSERT(bucket);
p6->ip6q_prev->ip6q_next = p6->ip6q_next;
p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
V_ip6q[bucket].count--;
}
/*
* IPv6 reassembling timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
frag6_slowtimo(void)
{
VNET_ITERATOR_DECL(vnet_iter);
struct ip6q *head, *q6;
int i;
VNET_LIST_RLOCK_NOSLEEP();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
for (i = 0; i < IP6REASS_NHASH; i++) {
IP6Q_LOCK(i);
head = IP6Q_HEAD(i);
q6 = head->ip6q_next;
if (q6 == NULL) {
/*
* XXXJTL: This should never happen. This
* should turn into an assertion.
*/
IP6Q_UNLOCK(i);
continue;
}
while (q6 != head) {
--q6->ip6q_ttl;
q6 = q6->ip6q_next;
if (q6->ip6q_prev->ip6q_ttl == 0) {
IP6STAT_INC(ip6s_fragtimeout);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(q6->ip6q_prev, i);
}
}
/*
* 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
* is negative.
*/
while ((V_ip6_maxfragpackets == 0 ||
(V_ip6_maxfragpackets > 0 &&
V_ip6q[i].count > V_ip6_maxfragbucketsize)) &&
head->ip6q_prev != head) {
IP6STAT_INC(ip6s_fragoverflow);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(head->ip6q_prev, i);
}
IP6Q_UNLOCK(i);
}
/*
* If we are still over the maximum number of fragmented
* packets, drain off enough to get down to the new limit.
*/
i = 0;
while (V_ip6_maxfragpackets >= 0 &&
atomic_load_int(&V_frag6_nfragpackets) >
(u_int)V_ip6_maxfragpackets) {
IP6Q_LOCK(i);
head = IP6Q_HEAD(i);
if (head->ip6q_prev != head) {
IP6STAT_INC(ip6s_fragoverflow);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(head->ip6q_prev, i);
}
IP6Q_UNLOCK(i);
i = (i + 1) % IP6REASS_NHASH;
}
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK_NOSLEEP();
}
/*
* Drain off all datagram fragments.
*/
void
frag6_drain(void)
{
VNET_ITERATOR_DECL(vnet_iter);
struct ip6q *head;
int i;
VNET_LIST_RLOCK_NOSLEEP();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
for (i = 0; i < IP6REASS_NHASH; i++) {
if (IP6Q_TRYLOCK(i) == 0)
continue;
head = IP6Q_HEAD(i);
while (head->ip6q_next != head) {
IP6STAT_INC(ip6s_fragdropped);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(head->ip6q_next, i);
}
IP6Q_UNLOCK(i);
}
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK_NOSLEEP();
}
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);
}
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