/*-
* 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
