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2946a9415c
freebsd-skq/sys/netinet6/frag6.c
Tom Jones 2946a9415c Add stat counter for ipv6 atomic fragments 
Add a stat counter to track ipv6 atomic fragments. Atomic fragments can be
generated in response to invalid path MTU values, but are also a potential
attack vector and considered harmful (see RFC6946 and RFC8021).

While here add tracking of the atomic fragment counter to netstat and systat.

Reviewed by:    tuexen, jtl, bz
Approved by:    jtl (mentor), bz (mentor)
Event:  Aberdeen hackathon 2019
Differential Revision:  https://reviews.freebsd.org/D17511
2019-04-19 17:06:43 +00:00

967 lines
26 KiB
C
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/*-
* 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);
/*
* 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.
*/
if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
IP6STAT_INC(ip6s_atomicfrags);
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_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
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_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
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_ADD(ip6s_fragtimeout,
q6->ip6q_prev->ip6q_nfrag);
/* 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_ADD(ip6s_fragoverflow,
q6->ip6q_prev->ip6q_nfrag);
/* 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_ADD(ip6s_fragoverflow,
q6->ip6q_prev->ip6q_nfrag);
/* 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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