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freebsd-dev/sys/netinet/ip_reass.c
Hans Petter Selasky a55383e720 Fix panic in network stack due to use after free when receiving 
partial fragmented packets before a network interface is detached.

When sending IPv4 or IPv6 fragmented packets and a fragment is lost
before the network device is freed, the mbuf making up the fragment
will remain in the temporary hashed fragment list and cause a panic
when it times out due to accessing a freed network interface
structure.


1) Make sure the m_pkthdr.rcvif always points to a valid network
interface. Else the rcvif field should be set to NULL.

2) Use the rcvif of the last received fragment as m_pkthdr.rcvif for
the fully defragged packet, instead of the first received fragment.

Panic backtrace for IPv6:

panic()
icmp6_reflect() # tries to access rcvif->if_afdata[AF_INET6]->xxx
icmp6_error()
frag6_freef()
frag6_slowtimo()
pfslowtimo()
softclock_call_cc()
softclock()
ithread_loop()

Reviewed by:	bz
Differential Revision:	https://reviews.freebsd.org/D19622
MFC after:	1 week
Sponsored by:	Mellanox Technologies
2019-10-16 09:11:49 +00:00

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/*-
* Copyright (c) 2015 Gleb Smirnoff <glebius@FreeBSD.org>
* Copyright (c) 2015 Adrian Chadd <adrian@FreeBSD.org>
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. 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 University 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 REGENTS 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 REGENTS 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.
*
* @(#)ip_input.c 8.2 (Berkeley) 1/4/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_rss.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/hash.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/rss_config.h>
#include <net/netisr.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/in_rss.h>
#ifdef MAC
#include <security/mac/mac_framework.h>
#endif
SYSCTL_DECL(_net_inet_ip);
/*
* Reassembly headers are stored in hash buckets.
*/
#define IPREASS_NHASH_LOG2 10
#define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
#define IPREASS_HMASK (IPREASS_NHASH - 1)
struct ipqbucket {
TAILQ_HEAD(ipqhead, ipq) head;
struct mtx lock;
int count;
};
VNET_DEFINE_STATIC(struct ipqbucket, ipq[IPREASS_NHASH]);
#define V_ipq VNET(ipq)
VNET_DEFINE_STATIC(uint32_t, ipq_hashseed);
#define V_ipq_hashseed VNET(ipq_hashseed)
#define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock)
#define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
#define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock)
#define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED)
VNET_DEFINE_STATIC(int, ipreass_maxbucketsize);
#define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize)
void ipreass_init(void);
void ipreass_drain(void);
void ipreass_slowtimo(void);
#ifdef VIMAGE
void ipreass_destroy(void);
#endif
static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS);
static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS);
static void ipreass_zone_change(void *);
static void ipreass_drain_tomax(void);
static void ipq_free(struct ipqbucket *, struct ipq *);
static struct ipq * ipq_reuse(int);
static inline void
ipq_timeout(struct ipqbucket *bucket, struct ipq *fp)
{
IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
ipq_free(bucket, fp);
}
static inline void
ipq_drop(struct ipqbucket *bucket, struct ipq *fp)
{
IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
ipq_free(bucket, fp);
}
/*
* By default, limit the number of IP 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
* IP 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 IP_MAXFRAGS (nmbclusters / 32)
#define IP_MAXFRAGPACKETS (imin(IP_MAXFRAGS, IPREASS_NHASH * 50))
static int maxfrags;
static volatile u_int nfrags;
SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfrags, CTLFLAG_RW,
&maxfrags, 0,
"Maximum number of IPv4 fragments allowed across all reassembly queues");
SYSCTL_UINT(_net_inet_ip, OID_AUTO, curfrags, CTLFLAG_RD,
__DEVOLATILE(u_int *, &nfrags), 0,
"Current number of IPv4 fragments across all reassembly queues");
VNET_DEFINE_STATIC(uma_zone_t, ipq_zone);
#define V_ipq_zone VNET(ipq_zone)
SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_VNET |
CTLTYPE_INT | CTLFLAG_RW, NULL, 0, sysctl_maxfragpackets, "I",
"Maximum number of IPv4 fragment reassembly queue entries");
SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET,
&VNET_NAME(ipq_zone),
"Current number of IPv4 fragment reassembly queue entries");
VNET_DEFINE_STATIC(int, noreass);
#define V_noreass VNET(noreass)
VNET_DEFINE_STATIC(int, maxfragsperpacket);
#define V_maxfragsperpacket VNET(maxfragsperpacket)
SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(maxfragsperpacket), 0,
"Maximum number of IPv4 fragments allowed per packet");
SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
sysctl_maxfragbucketsize, "I",
"Maximum number of IPv4 fragment reassembly queue entries per bucket");
/*
* Take incoming datagram fragment and try to reassemble it into
* whole datagram. If the argument is the first fragment or one
* in between the function will return NULL and store the mbuf
* in the fragment chain. If the argument is the last fragment
* the packet will be reassembled and the pointer to the new
* mbuf returned for further processing. Only m_tags attached
* to the first packet/fragment are preserved.
* The IP header is *NOT* adjusted out of iplen.
*/
#define M_IP_FRAG M_PROTO9
struct mbuf *
ip_reass(struct mbuf *m)
{
struct ip *ip;
struct mbuf *p, *q, *nq, *t;
struct ipq *fp;
struct ifnet *srcifp;
struct ipqhead *head;
int i, hlen, next, tmpmax;
u_int8_t ecn, ecn0;
uint32_t hash, hashkey[3];
#ifdef RSS
uint32_t rss_hash, rss_type;
#endif
/*
* If no reassembling or maxfragsperpacket are 0,
* never accept fragments.
* Also, drop packet if it would exceed the maximum
* number of fragments.
*/
tmpmax = maxfrags;
if (V_noreass == 1 || V_maxfragsperpacket == 0 ||
(tmpmax >= 0 && atomic_load_int(&nfrags) >= (u_int)tmpmax)) {
IPSTAT_INC(ips_fragments);
IPSTAT_INC(ips_fragdropped);
m_freem(m);
return (NULL);
}
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
/*
* Adjust ip_len to not reflect header,
* convert offset of this to bytes.
*/
ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
/*
* Make sure that fragments have a data length
* that's a non-zero multiple of 8 bytes, unless
* this is the last fragment.
*/
if (ip->ip_len == htons(0) ||
((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) {
IPSTAT_INC(ips_toosmall); /* XXX */
IPSTAT_INC(ips_fragdropped);
m_freem(m);
return (NULL);
}
if (ip->ip_off & htons(IP_MF))
m->m_flags |= M_IP_FRAG;
else
m->m_flags &= ~M_IP_FRAG;
ip->ip_off = htons(ntohs(ip->ip_off) << 3);
/*
* Make sure the fragment lies within a packet of valid size.
*/
if (ntohs(ip->ip_len) + ntohs(ip->ip_off) > IP_MAXPACKET) {
IPSTAT_INC(ips_toolong);
IPSTAT_INC(ips_fragdropped);
m_freem(m);
return (NULL);
}
/*
* Store receive network interface pointer for later.
*/
srcifp = m->m_pkthdr.rcvif;
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
IPSTAT_INC(ips_fragments);
m->m_pkthdr.PH_loc.ptr = ip;
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->m_data += hlen;
m->m_len -= hlen;
hashkey[0] = ip->ip_src.s_addr;
hashkey[1] = ip->ip_dst.s_addr;
hashkey[2] = (uint32_t)ip->ip_p << 16;
hashkey[2] += ip->ip_id;
hash = jenkins_hash32(hashkey, nitems(hashkey), V_ipq_hashseed);
hash &= IPREASS_HMASK;
head = &V_ipq[hash].head;
IPQ_LOCK(hash);
/*
* Look for queue of fragments
* of this datagram.
*/
TAILQ_FOREACH(fp, head, ipq_list)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src.s_addr == fp->ipq_src.s_addr &&
ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
#ifdef MAC
mac_ipq_match(m, fp) &&
#endif
ip->ip_p == fp->ipq_p)
break;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == NULL) {
if (V_ipq[hash].count < V_ipreass_maxbucketsize)
fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
if (fp == NULL)
fp = ipq_reuse(hash);
if (fp == NULL)
goto dropfrag;
#ifdef MAC
if (mac_ipq_init(fp, M_NOWAIT) != 0) {
uma_zfree(V_ipq_zone, fp);
fp = NULL;
goto dropfrag;
}
mac_ipq_create(m, fp);
#endif
TAILQ_INSERT_HEAD(head, fp, ipq_list);
V_ipq[hash].count++;
fp->ipq_nfrags = 1;
atomic_add_int(&nfrags, 1);
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_src = ip->ip_src;
fp->ipq_dst = ip->ip_dst;
fp->ipq_frags = m;
if (m->m_flags & M_IP_FRAG)
fp->ipq_maxoff = -1;
else
fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
m->m_nextpkt = NULL;
goto done;
} else {
/*
* If we already saw the last fragment, make sure
* this fragment's offset looks sane. Otherwise, if
* this is the last fragment, record its endpoint.
*/
if (fp->ipq_maxoff > 0) {
i = ntohs(ip->ip_off) + ntohs(ip->ip_len);
if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) ||
((m->m_flags & M_IP_FRAG) == 0 &&
i != fp->ipq_maxoff)) {
fp = NULL;
goto dropfrag;
}
} else if ((m->m_flags & M_IP_FRAG) == 0)
fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
fp->ipq_nfrags++;
atomic_add_int(&nfrags, 1);
#ifdef MAC
mac_ipq_update(m, fp);
#endif
}
#define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr))
/*
* 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 = ip->ip_tos & IPTOS_ECN_MASK;
ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
if (ecn == IPTOS_ECN_CE) {
if (ecn0 == IPTOS_ECN_NOTECT)
goto dropfrag;
if (ecn0 != IPTOS_ECN_CE)
GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
}
if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
goto dropfrag;
/*
* Find a segment which begins after this one does.
*/
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
break;
/*
* 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, otherwise
* stick new segment in the proper place.
*
* If some of the data is dropped from the preceding
* segment, then it's checksum is invalidated.
*/
if (p) {
i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
ntohs(ip->ip_off);
if (i > 0) {
if (i >= ntohs(ip->ip_len))
goto dropfrag;
m_adj(m, i);
m->m_pkthdr.csum_flags = 0;
ip->ip_off = htons(ntohs(ip->ip_off) + i);
ip->ip_len = htons(ntohs(ip->ip_len) - i);
}
m->m_nextpkt = p->m_nextpkt;
p->m_nextpkt = m;
} else {
m->m_nextpkt = fp->ipq_frags;
fp->ipq_frags = m;
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
ntohs(GETIP(q)->ip_off); q = nq) {
i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
ntohs(GETIP(q)->ip_off);
if (i < ntohs(GETIP(q)->ip_len)) {
GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
m_adj(q, i);
q->m_pkthdr.csum_flags = 0;
break;
}
nq = q->m_nextpkt;
m->m_nextpkt = nq;
IPSTAT_INC(ips_fragdropped);
fp->ipq_nfrags--;
atomic_subtract_int(&nfrags, 1);
m_freem(q);
}
/*
* Check for complete reassembly and perform frag per packet
* limiting.
*
* Frag limiting is performed here so that the nth frag has
* a chance to complete the packet before we drop the packet.
* As a result, n+1 frags are actually allowed per packet, but
* only n will ever be stored. (n = maxfragsperpacket.)
*
*/
next = 0;
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
if (ntohs(GETIP(q)->ip_off) != next) {
if (fp->ipq_nfrags > V_maxfragsperpacket)
ipq_drop(&V_ipq[hash], fp);
goto done;
}
next += ntohs(GETIP(q)->ip_len);
}
/* Make sure the last packet didn't have the IP_MF flag */
if (p->m_flags & M_IP_FRAG) {
if (fp->ipq_nfrags > V_maxfragsperpacket)
ipq_drop(&V_ipq[hash], fp);
goto done;
}
/*
* Reassembly is complete. Make sure the packet is a sane size.
*/
q = fp->ipq_frags;
ip = GETIP(q);
if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
IPSTAT_INC(ips_toolong);
ipq_drop(&V_ipq[hash], fp);
goto done;
}
/*
* Concatenate fragments.
*/
m = q;
t = m->m_next;
m->m_next = NULL;
m_cat(m, t);
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
for (q = nq; q != NULL; q = nq) {
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
m_demote_pkthdr(q);
m_cat(m, q);
}
/*
* In order to do checksumming faster we do 'end-around carry' here
* (and not in for{} loop), though it implies we are not going to
* reassemble more than 64k fragments.
*/
while (m->m_pkthdr.csum_data & 0xffff0000)
m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
(m->m_pkthdr.csum_data >> 16);
atomic_subtract_int(&nfrags, fp->ipq_nfrags);
#ifdef MAC
mac_ipq_reassemble(fp, m);
mac_ipq_destroy(fp);
#endif
/*
* Create header for new ip packet by modifying header of first
* packet; dequeue and discard fragment reassembly header.
* Make header visible.
*/
ip->ip_len = htons((ip->ip_hl << 2) + next);
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
TAILQ_REMOVE(head, fp, ipq_list);
V_ipq[hash].count--;
uma_zfree(V_ipq_zone, fp);
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
/* some debugging cruft by sklower, below, will go away soon */
if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
m_fixhdr(m);
/* set valid receive interface pointer */
m->m_pkthdr.rcvif = srcifp;
}
IPSTAT_INC(ips_reassembled);
IPQ_UNLOCK(hash);
#ifdef RSS
/*
* Query the RSS layer for the flowid / flowtype for the
* mbuf payload.
*
* For now, just assume we have to calculate a new one.
* Later on we should check to see if the assigned flowid matches
* what RSS wants for the given IP protocol and if so, just keep it.
*
* We then queue into the relevant netisr so it can be dispatched
* to the correct CPU.
*
* Note - this may return 1, which means the flowid in the mbuf
* is correct for the configured RSS hash types and can be used.
*/
if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) {
m->m_pkthdr.flowid = rss_hash;
M_HASHTYPE_SET(m, rss_type);
}
/*
* Queue/dispatch for reprocessing.
*
* Note: this is much slower than just handling the frame in the
* current receive context. It's likely worth investigating
* why this is.
*/
netisr_dispatch(NETISR_IP_DIRECT, m);
return (NULL);
#endif
/* Handle in-line */
return (m);
dropfrag:
IPSTAT_INC(ips_fragdropped);
if (fp != NULL) {
fp->ipq_nfrags--;
atomic_subtract_int(&nfrags, 1);
}
m_freem(m);
done:
IPQ_UNLOCK(hash);
return (NULL);
#undef GETIP
}
/*
* Initialize IP reassembly structures.
*/
void
ipreass_init(void)
{
int max;
for (int i = 0; i < IPREASS_NHASH; i++) {
TAILQ_INIT(&V_ipq[i].head);
mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
MTX_DEF | MTX_DUPOK);
V_ipq[i].count = 0;
}
V_ipq_hashseed = arc4random();
V_maxfragsperpacket = 16;
V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
NULL, UMA_ALIGN_PTR, 0);
max = IP_MAXFRAGPACKETS;
max = uma_zone_set_max(V_ipq_zone, max);
V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
if (IS_DEFAULT_VNET(curvnet)) {
maxfrags = IP_MAXFRAGS;
EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change,
NULL, EVENTHANDLER_PRI_ANY);
}
}
/*
* If a timer expires on a reassembly queue, discard it.
*/
void
ipreass_slowtimo(void)
{
struct ipq *fp, *tmp;
for (int i = 0; i < IPREASS_NHASH; i++) {
IPQ_LOCK(i);
TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, tmp)
if (--fp->ipq_ttl == 0)
ipq_timeout(&V_ipq[i], fp);
IPQ_UNLOCK(i);
}
}
/*
* Drain off all datagram fragments.
*/
void
ipreass_drain(void)
{
for (int i = 0; i < IPREASS_NHASH; i++) {
IPQ_LOCK(i);
while(!TAILQ_EMPTY(&V_ipq[i].head))
ipq_drop(&V_ipq[i], TAILQ_FIRST(&V_ipq[i].head));
KASSERT(V_ipq[i].count == 0,
("%s: V_ipq[%d] count %d (V_ipq=%p)", __func__, i,
V_ipq[i].count, V_ipq));
IPQ_UNLOCK(i);
}
}
/*
* Drain off all datagram fragments belonging to
* the given network interface.
*/
static void
ipreass_cleanup(void *arg __unused, struct ifnet *ifp)
{
struct ipq *fp, *temp;
struct mbuf *m;
int i;
KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
/*
* Skip processing if IPv4 reassembly is not initialised or
* torn down by ipreass_destroy().
*/
if (V_ipq_zone == NULL)
return;
CURVNET_SET_QUIET(ifp->if_vnet);
for (i = 0; i < IPREASS_NHASH; i++) {
IPQ_LOCK(i);
/* Scan fragment list. */
TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, temp) {
for (m = fp->ipq_frags; m != NULL; m = m->m_nextpkt) {
/* clear no longer valid rcvif pointer */
if (m->m_pkthdr.rcvif == ifp)
m->m_pkthdr.rcvif = NULL;
}
}
IPQ_UNLOCK(i);
}
CURVNET_RESTORE();
}
EVENTHANDLER_DEFINE(ifnet_departure_event, ipreass_cleanup, NULL, 0);
#ifdef VIMAGE
/*
* Destroy IP reassembly structures.
*/
void
ipreass_destroy(void)
{
ipreass_drain();
uma_zdestroy(V_ipq_zone);
V_ipq_zone = NULL;
for (int i = 0; i < IPREASS_NHASH; i++)
mtx_destroy(&V_ipq[i].lock);
}
#endif
/*
* After maxnipq has been updated, propagate the change to UMA. The UMA zone
* max has slightly different semantics than the sysctl, for historical
* reasons.
*/
static void
ipreass_drain_tomax(void)
{
struct ipq *fp;
int target;
/*
* Make sure each bucket is under the new limit. If
* necessary, drop enough of the oldest elements from
* each bucket to get under the new limit.
*/
for (int i = 0; i < IPREASS_NHASH; i++) {
IPQ_LOCK(i);
while (V_ipq[i].count > V_ipreass_maxbucketsize &&
(fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL)
ipq_timeout(&V_ipq[i], fp);
IPQ_UNLOCK(i);
}
/*
* If we are over the maximum number of fragments,
* drain off enough to get down to the new limit,
* stripping off last elements on queues. Every
* run we strip the oldest element from each bucket.
*/
target = uma_zone_get_max(V_ipq_zone);
while (uma_zone_get_cur(V_ipq_zone) > target) {
for (int i = 0; i < IPREASS_NHASH; i++) {
IPQ_LOCK(i);
fp = TAILQ_LAST(&V_ipq[i].head, ipqhead);
if (fp != NULL)
ipq_timeout(&V_ipq[i], fp);
IPQ_UNLOCK(i);
}
}
}
static void
ipreass_zone_change(void *tag)
{
VNET_ITERATOR_DECL(vnet_iter);
int max;
maxfrags = IP_MAXFRAGS;
max = IP_MAXFRAGPACKETS;
VNET_LIST_RLOCK_NOSLEEP();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
max = uma_zone_set_max(V_ipq_zone, max);
V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
ipreass_drain_tomax();
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK_NOSLEEP();
}
/*
* Change the limit on the UMA zone, or disable the fragment allocation
* at all. Since 0 and -1 is a special values here, we need our own handler,
* instead of sysctl_handle_uma_zone_max().
*/
static int
sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)
{
int error, max;
if (V_noreass == 0) {
max = uma_zone_get_max(V_ipq_zone);
if (max == 0)
max = -1;
} else
max = 0;
error = sysctl_handle_int(oidp, &max, 0, req);
if (error || !req->newptr)
return (error);
if (max > 0) {
/*
* XXXRW: Might be a good idea to sanity check the argument
* and place an extreme upper bound.
*/
max = uma_zone_set_max(V_ipq_zone, max);
V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
ipreass_drain_tomax();
V_noreass = 0;
} else if (max == 0) {
V_noreass = 1;
ipreass_drain();
} else if (max == -1) {
V_noreass = 0;
uma_zone_set_max(V_ipq_zone, 0);
V_ipreass_maxbucketsize = INT_MAX;
} else
return (EINVAL);
return (0);
}
/*
* Seek for old fragment queue header that can be reused. Try to
* reuse a header from currently locked hash bucket.
*/
static struct ipq *
ipq_reuse(int start)
{
struct ipq *fp;
int bucket, i;
IPQ_LOCK_ASSERT(start);
for (i = 0; i < IPREASS_NHASH; i++) {
bucket = (start + i) % IPREASS_NHASH;
if (bucket != start && IPQ_TRYLOCK(bucket) == 0)
continue;
fp = TAILQ_LAST(&V_ipq[bucket].head, ipqhead);
if (fp) {
struct mbuf *m;
IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
atomic_subtract_int(&nfrags, fp->ipq_nfrags);
while (fp->ipq_frags) {
m = fp->ipq_frags;
fp->ipq_frags = m->m_nextpkt;
m_freem(m);
}
TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list);
V_ipq[bucket].count--;
if (bucket != start)
IPQ_UNLOCK(bucket);
break;
}
if (bucket != start)
IPQ_UNLOCK(bucket);
}
IPQ_LOCK_ASSERT(start);
return (fp);
}
/*
* Free a fragment reassembly header and all associated datagrams.
*/
static void
ipq_free(struct ipqbucket *bucket, struct ipq *fp)
{
struct mbuf *q;
atomic_subtract_int(&nfrags, fp->ipq_nfrags);
while (fp->ipq_frags) {
q = fp->ipq_frags;
fp->ipq_frags = q->m_nextpkt;
m_freem(q);
}
TAILQ_REMOVE(&bucket->head, fp, ipq_list);
bucket->count--;
uma_zfree(V_ipq_zone, fp);
}
/*
* Get or set the maximum number of reassembly queues per bucket.
*/
static int
sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)
{
int error, max;
max = V_ipreass_maxbucketsize;
error = sysctl_handle_int(oidp, &max, 0, req);
if (error || !req->newptr)
return (error);
if (max <= 0)
return (EINVAL);
V_ipreass_maxbucketsize = max;
ipreass_drain_tomax();
return (0);
}
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