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pf_norm.c
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pf_norm.c
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/*-
* Copyright 2001 Niels Provos <provos@citi.umich.edu>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_pf.h"
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/refcount.h>
#include <sys/rwlock.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/vnet.h>
#include <net/pfvar.h>
#include <net/if_pflog.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#ifdef INET6
#include <netinet/ip6.h>
#endif /* INET6 */
struct pf_frent {
LIST_ENTRY(pf_frent) fr_next;
union {
struct {
struct ip *_fr_ip;
struct mbuf *_fr_m;
} _frag;
struct {
uint16_t _fr_off;
uint16_t _fr_end;
} _cache;
} _u;
};
#define fr_ip _u._frag._fr_ip
#define fr_m _u._frag._fr_m
#define fr_off _u._cache._fr_off
#define fr_end _u._cache._fr_end
struct pf_fragment {
RB_ENTRY(pf_fragment) fr_entry;
TAILQ_ENTRY(pf_fragment) frag_next;
struct in_addr fr_src;
struct in_addr fr_dst;
u_int8_t fr_p; /* protocol of this fragment */
u_int8_t fr_flags; /* status flags */
#define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */
#define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */
#define PFFRAG_DROP 0x0004 /* Drop all fragments */
#define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER))
u_int16_t fr_id; /* fragment id for reassemble */
u_int16_t fr_max; /* fragment data max */
u_int32_t fr_timeout;
LIST_HEAD(, pf_frent) fr_queue;
};
static struct mtx pf_frag_mtx;
#define PF_FRAG_LOCK() mtx_lock(&pf_frag_mtx)
#define PF_FRAG_UNLOCK() mtx_unlock(&pf_frag_mtx)
#define PF_FRAG_ASSERT() mtx_assert(&pf_frag_mtx, MA_OWNED)
VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */
static VNET_DEFINE(uma_zone_t, pf_frent_z);
#define V_pf_frent_z VNET(pf_frent_z)
static VNET_DEFINE(uma_zone_t, pf_frag_z);
#define V_pf_frag_z VNET(pf_frag_z)
TAILQ_HEAD(pf_fragqueue, pf_fragment);
TAILQ_HEAD(pf_cachequeue, pf_fragment);
static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
#define V_pf_fragqueue VNET(pf_fragqueue)
static VNET_DEFINE(struct pf_cachequeue, pf_cachequeue);
#define V_pf_cachequeue VNET(pf_cachequeue)
RB_HEAD(pf_frag_tree, pf_fragment);
static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
#define V_pf_frag_tree VNET(pf_frag_tree)
static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree);
#define V_pf_cache_tree VNET(pf_cache_tree)
static int pf_frag_compare(struct pf_fragment *,
struct pf_fragment *);
static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
/* Private prototypes */
static void pf_free_fragment(struct pf_fragment *);
static void pf_remove_fragment(struct pf_fragment *);
static int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
struct tcphdr *, int, sa_family_t);
#ifdef INET
static void pf_ip2key(struct pf_fragment *, struct ip *);
static void pf_scrub_ip(struct mbuf **, u_int32_t, u_int8_t,
u_int8_t);
static void pf_flush_fragments(void);
static struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *);
static struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **,
struct pf_frent *, int);
static struct mbuf *pf_fragcache(struct mbuf **, struct ip*,
struct pf_fragment **, int, int, int *);
#endif /* INET */
#ifdef INET6
static void pf_scrub_ip6(struct mbuf **, u_int8_t);
#endif
#define DPFPRINTF(x) do { \
if (V_pf_status.debug >= PF_DEBUG_MISC) { \
printf("%s: ", __func__); \
printf x ; \
} \
} while(0)
void
pf_normalize_init(void)
{
V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
TAILQ_INIT(&V_pf_fragqueue);
TAILQ_INIT(&V_pf_cachequeue);
}
void
pf_normalize_cleanup(void)
{
uma_zdestroy(V_pf_state_scrub_z);
uma_zdestroy(V_pf_frent_z);
uma_zdestroy(V_pf_frag_z);
mtx_destroy(&pf_frag_mtx);
}
static int
pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
{
int diff;
if ((diff = a->fr_id - b->fr_id))
return (diff);
else if ((diff = a->fr_p - b->fr_p))
return (diff);
else if (a->fr_src.s_addr < b->fr_src.s_addr)
return (-1);
else if (a->fr_src.s_addr > b->fr_src.s_addr)
return (1);
else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
return (-1);
else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
return (1);
return (0);
}
void
pf_purge_expired_fragments(void)
{
struct pf_fragment *frag;
u_int32_t expire = time_uptime -
V_pf_default_rule.timeout[PFTM_FRAG];
PF_FRAG_LOCK();
while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
KASSERT((BUFFER_FRAGMENTS(frag)),
("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__));
if (frag->fr_timeout > expire)
break;
DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
pf_free_fragment(frag);
}
while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) {
KASSERT((!BUFFER_FRAGMENTS(frag)),
("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__));
if (frag->fr_timeout > expire)
break;
DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
pf_free_fragment(frag);
KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) ||
TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag),
("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
__FUNCTION__));
}
PF_FRAG_UNLOCK();
}
#ifdef INET
/*
* Try to flush old fragments to make space for new ones
*/
static void
pf_flush_fragments(void)
{
struct pf_fragment *frag, *cache;
int goal;
PF_FRAG_ASSERT();
goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
DPFPRINTF(("trying to free %d frag entriess\n", goal));
while (goal < uma_zone_get_cur(V_pf_frent_z)) {
frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
if (frag)
pf_free_fragment(frag);
cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue);
if (cache)
pf_free_fragment(cache);
if (frag == NULL && cache == NULL)
break;
}
}
#endif /* INET */
/* Frees the fragments and all associated entries */
static void
pf_free_fragment(struct pf_fragment *frag)
{
struct pf_frent *frent;
PF_FRAG_ASSERT();
/* Free all fragments */
if (BUFFER_FRAGMENTS(frag)) {
for (frent = LIST_FIRST(&frag->fr_queue); frent;
frent = LIST_FIRST(&frag->fr_queue)) {
LIST_REMOVE(frent, fr_next);
m_freem(frent->fr_m);
uma_zfree(V_pf_frent_z, frent);
}
} else {
for (frent = LIST_FIRST(&frag->fr_queue); frent;
frent = LIST_FIRST(&frag->fr_queue)) {
LIST_REMOVE(frent, fr_next);
KASSERT((LIST_EMPTY(&frag->fr_queue) ||
LIST_FIRST(&frag->fr_queue)->fr_off >
frent->fr_end),
("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
" frent->fr_end): %s", __func__));
uma_zfree(V_pf_frent_z, frent);
}
}
pf_remove_fragment(frag);
}
#ifdef INET
static void
pf_ip2key(struct pf_fragment *key, struct ip *ip)
{
key->fr_p = ip->ip_p;
key->fr_id = ip->ip_id;
key->fr_src.s_addr = ip->ip_src.s_addr;
key->fr_dst.s_addr = ip->ip_dst.s_addr;
}
static struct pf_fragment *
pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
{
struct pf_fragment key;
struct pf_fragment *frag;
PF_FRAG_ASSERT();
pf_ip2key(&key, ip);
frag = RB_FIND(pf_frag_tree, tree, &key);
if (frag != NULL) {
/* XXX Are we sure we want to update the timeout? */
frag->fr_timeout = time_uptime;
if (BUFFER_FRAGMENTS(frag)) {
TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
} else {
TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next);
}
}
return (frag);
}
#endif /* INET */
/* Removes a fragment from the fragment queue and frees the fragment */
static void
pf_remove_fragment(struct pf_fragment *frag)
{
PF_FRAG_ASSERT();
if (BUFFER_FRAGMENTS(frag)) {
RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
uma_zfree(V_pf_frag_z, frag);
} else {
RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag);
TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
uma_zfree(V_pf_frag_z, frag);
}
}
#ifdef INET
#define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3)
static struct mbuf *
pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
struct pf_frent *frent, int mff)
{
struct mbuf *m = *m0, *m2;
struct pf_frent *frea, *next;
struct pf_frent *frep = NULL;
struct ip *ip = frent->fr_ip;
int hlen = ip->ip_hl << 2;
u_int16_t off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
u_int16_t ip_len = ntohs(ip->ip_len) - ip->ip_hl * 4;
u_int16_t max = ip_len + off;
PF_FRAG_ASSERT();
KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
/* Strip off ip header */
m->m_data += hlen;
m->m_len -= hlen;
/* Create a new reassembly queue for this packet */
if (*frag == NULL) {
*frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
if (*frag == NULL) {
pf_flush_fragments();
*frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
if (*frag == NULL)
goto drop_fragment;
}
(*frag)->fr_flags = 0;
(*frag)->fr_max = 0;
(*frag)->fr_src = frent->fr_ip->ip_src;
(*frag)->fr_dst = frent->fr_ip->ip_dst;
(*frag)->fr_p = frent->fr_ip->ip_p;
(*frag)->fr_id = frent->fr_ip->ip_id;
(*frag)->fr_timeout = time_uptime;
LIST_INIT(&(*frag)->fr_queue);
RB_INSERT(pf_frag_tree, &V_pf_frag_tree, *frag);
TAILQ_INSERT_HEAD(&V_pf_fragqueue, *frag, frag_next);
/* We do not have a previous fragment */
frep = NULL;
goto insert;
}
/*
* Find a fragment after the current one:
* - off contains the real shifted offset.
*/
LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
if (FR_IP_OFF(frea) > off)
break;
frep = frea;
}
KASSERT((frep != NULL || frea != NULL),
("!(frep != NULL || frea != NULL): %s", __FUNCTION__));;
if (frep != NULL &&
FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl *
4 > off)
{
u_int16_t precut;
precut = FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) -
frep->fr_ip->ip_hl * 4 - off;
if (precut >= ip_len)
goto drop_fragment;
m_adj(frent->fr_m, precut);
DPFPRINTF(("overlap -%d\n", precut));
/* Enforce 8 byte boundaries */
ip->ip_off = htons(ntohs(ip->ip_off) + (precut >> 3));
off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
ip_len -= precut;
ip->ip_len = htons(ip_len);
}
for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
frea = next)
{
u_int16_t aftercut;
aftercut = ip_len + off - FR_IP_OFF(frea);
DPFPRINTF(("adjust overlap %d\n", aftercut));
if (aftercut < ntohs(frea->fr_ip->ip_len) - frea->fr_ip->ip_hl
* 4)
{
frea->fr_ip->ip_len =
htons(ntohs(frea->fr_ip->ip_len) - aftercut);
frea->fr_ip->ip_off = htons(ntohs(frea->fr_ip->ip_off) +
(aftercut >> 3));
m_adj(frea->fr_m, aftercut);
break;
}
/* This fragment is completely overlapped, lose it */
next = LIST_NEXT(frea, fr_next);
m_freem(frea->fr_m);
LIST_REMOVE(frea, fr_next);
uma_zfree(V_pf_frent_z, frea);
}
insert:
/* Update maximum data size */
if ((*frag)->fr_max < max)
(*frag)->fr_max = max;
/* This is the last segment */
if (!mff)
(*frag)->fr_flags |= PFFRAG_SEENLAST;
if (frep == NULL)
LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
else
LIST_INSERT_AFTER(frep, frent, fr_next);
/* Check if we are completely reassembled */
if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
return (NULL);
/* Check if we have all the data */
off = 0;
for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
next = LIST_NEXT(frep, fr_next);
off += ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 4;
if (off < (*frag)->fr_max &&
(next == NULL || FR_IP_OFF(next) != off))
{
DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
off, next == NULL ? -1 : FR_IP_OFF(next),
(*frag)->fr_max));
return (NULL);
}
}
DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
if (off < (*frag)->fr_max)
return (NULL);
/* We have all the data */
frent = LIST_FIRST(&(*frag)->fr_queue);
KASSERT((frent != NULL), ("frent == NULL: %s", __FUNCTION__));
if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
DPFPRINTF(("drop: too big: %d\n", off));
pf_free_fragment(*frag);
*frag = NULL;
return (NULL);
}
next = LIST_NEXT(frent, fr_next);
/* Magic from ip_input */
ip = frent->fr_ip;
m = frent->fr_m;
m2 = m->m_next;
m->m_next = NULL;
m_cat(m, m2);
uma_zfree(V_pf_frent_z, frent);
for (frent = next; frent != NULL; frent = next) {
next = LIST_NEXT(frent, fr_next);
m2 = frent->fr_m;
uma_zfree(V_pf_frent_z, frent);
m->m_pkthdr.csum_flags &= m2->m_pkthdr.csum_flags;
m->m_pkthdr.csum_data += m2->m_pkthdr.csum_data;
m_cat(m, m2);
}
while (m->m_pkthdr.csum_data & 0xffff0000)
m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
(m->m_pkthdr.csum_data >> 16);
ip->ip_src = (*frag)->fr_src;
ip->ip_dst = (*frag)->fr_dst;
/* Remove from fragment queue */
pf_remove_fragment(*frag);
*frag = NULL;
hlen = ip->ip_hl << 2;
ip->ip_len = htons(off + hlen);
m->m_len += hlen;
m->m_data -= hlen;
/* some debugging cruft by sklower, below, will go away soon */
/* XXX this should be done elsewhere */
if (m->m_flags & M_PKTHDR) {
int plen = 0;
for (m2 = m; m2; m2 = m2->m_next)
plen += m2->m_len;
m->m_pkthdr.len = plen;
}
DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
return (m);
drop_fragment:
/* Oops - fail safe - drop packet */
uma_zfree(V_pf_frent_z, frent);
m_freem(m);
return (NULL);
}
static struct mbuf *
pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
int drop, int *nomem)
{
struct mbuf *m = *m0;
struct pf_frent *frp, *fra, *cur = NULL;
int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
u_int16_t off = ntohs(h->ip_off) << 3;
u_int16_t max = ip_len + off;
int hosed = 0;
PF_FRAG_ASSERT();
KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
/* Create a new range queue for this packet */
if (*frag == NULL) {
*frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
if (*frag == NULL) {
pf_flush_fragments();
*frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
if (*frag == NULL)
goto no_mem;
}
/* Get an entry for the queue */
cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
if (cur == NULL) {
uma_zfree(V_pf_frag_z, *frag);
*frag = NULL;
goto no_mem;
}
(*frag)->fr_flags = PFFRAG_NOBUFFER;
(*frag)->fr_max = 0;
(*frag)->fr_src = h->ip_src;
(*frag)->fr_dst = h->ip_dst;
(*frag)->fr_p = h->ip_p;
(*frag)->fr_id = h->ip_id;
(*frag)->fr_timeout = time_uptime;
cur->fr_off = off;
cur->fr_end = max;
LIST_INIT(&(*frag)->fr_queue);
LIST_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag);
TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next);
DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
goto pass;
}
/*
* Find a fragment after the current one:
* - off contains the real shifted offset.
*/
frp = NULL;
LIST_FOREACH(fra, &(*frag)->fr_queue, fr_next) {
if (fra->fr_off > off)
break;
frp = fra;
}
KASSERT((frp != NULL || fra != NULL),
("!(frp != NULL || fra != NULL): %s", __FUNCTION__));
if (frp != NULL) {
int precut;
precut = frp->fr_end - off;
if (precut >= ip_len) {
/* Fragment is entirely a duplicate */
DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
h->ip_id, frp->fr_off, frp->fr_end, off, max));
goto drop_fragment;
}
if (precut == 0) {
/* They are adjacent. Fixup cache entry */
DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
h->ip_id, frp->fr_off, frp->fr_end, off, max));
frp->fr_end = max;
} else if (precut > 0) {
/* The first part of this payload overlaps with a
* fragment that has already been passed.
* Need to trim off the first part of the payload.
* But to do so easily, we need to create another
* mbuf to throw the original header into.
*/
DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
h->ip_id, precut, frp->fr_off, frp->fr_end, off,
max));
off += precut;
max -= precut;
/* Update the previous frag to encompass this one */
frp->fr_end = max;
if (!drop) {
/* XXX Optimization opportunity
* This is a very heavy way to trim the payload.
* we could do it much faster by diddling mbuf
* internals but that would be even less legible
* than this mbuf magic. For my next trick,
* I'll pull a rabbit out of my laptop.
*/
*m0 = m_dup(m, M_NOWAIT);
if (*m0 == NULL)
goto no_mem;
/* From KAME Project : We have missed this! */
m_adj(*m0, (h->ip_hl << 2) -
(*m0)->m_pkthdr.len);
KASSERT(((*m0)->m_next == NULL),
("(*m0)->m_next != NULL: %s",
__FUNCTION__));
m_adj(m, precut + (h->ip_hl << 2));
m_cat(*m0, m);
m = *m0;
if (m->m_flags & M_PKTHDR) {
int plen = 0;
struct mbuf *t;
for (t = m; t; t = t->m_next)
plen += t->m_len;
m->m_pkthdr.len = plen;
}
h = mtod(m, struct ip *);
KASSERT(((int)m->m_len ==
ntohs(h->ip_len) - precut),
("m->m_len != ntohs(h->ip_len) - precut: %s",
__FUNCTION__));
h->ip_off = htons(ntohs(h->ip_off) +
(precut >> 3));
h->ip_len = htons(ntohs(h->ip_len) - precut);
} else {
hosed++;
}
} else {
/* There is a gap between fragments */
DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
max));
cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
if (cur == NULL)
goto no_mem;
cur->fr_off = off;
cur->fr_end = max;
LIST_INSERT_AFTER(frp, cur, fr_next);
}
}
if (fra != NULL) {
int aftercut;
int merge = 0;
aftercut = max - fra->fr_off;
if (aftercut == 0) {
/* Adjacent fragments */
DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
h->ip_id, off, max, fra->fr_off, fra->fr_end));
fra->fr_off = off;
merge = 1;
} else if (aftercut > 0) {
/* Need to chop off the tail of this fragment */
DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
h->ip_id, aftercut, off, max, fra->fr_off,
fra->fr_end));
fra->fr_off = off;
max -= aftercut;
merge = 1;
if (!drop) {
m_adj(m, -aftercut);
if (m->m_flags & M_PKTHDR) {
int plen = 0;
struct mbuf *t;
for (t = m; t; t = t->m_next)
plen += t->m_len;
m->m_pkthdr.len = plen;
}
h = mtod(m, struct ip *);
KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut),
("m->m_len != ntohs(h->ip_len) - aftercut: %s",
__FUNCTION__));
h->ip_len = htons(ntohs(h->ip_len) - aftercut);
} else {
hosed++;
}
} else if (frp == NULL) {
/* There is a gap between fragments */
DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
h->ip_id, -aftercut, off, max, fra->fr_off,
fra->fr_end));
cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
if (cur == NULL)
goto no_mem;
cur->fr_off = off;
cur->fr_end = max;
LIST_INSERT_BEFORE(fra, cur, fr_next);
}
/* Need to glue together two separate fragment descriptors */
if (merge) {
if (cur && fra->fr_off <= cur->fr_end) {
/* Need to merge in a previous 'cur' */
DPFPRINTF(("fragcache[%d]: adjacent(merge "
"%d-%d) %d-%d (%d-%d)\n",
h->ip_id, cur->fr_off, cur->fr_end, off,
max, fra->fr_off, fra->fr_end));
fra->fr_off = cur->fr_off;
LIST_REMOVE(cur, fr_next);
uma_zfree(V_pf_frent_z, cur);
cur = NULL;
} else if (frp && fra->fr_off <= frp->fr_end) {
/* Need to merge in a modified 'frp' */
KASSERT((cur == NULL), ("cur != NULL: %s",
__FUNCTION__));
DPFPRINTF(("fragcache[%d]: adjacent(merge "
"%d-%d) %d-%d (%d-%d)\n",
h->ip_id, frp->fr_off, frp->fr_end, off,
max, fra->fr_off, fra->fr_end));
fra->fr_off = frp->fr_off;
LIST_REMOVE(frp, fr_next);
uma_zfree(V_pf_frent_z, frp);
frp = NULL;
}
}
}
if (hosed) {
/*
* We must keep tracking the overall fragment even when
* we're going to drop it anyway so that we know when to
* free the overall descriptor. Thus we drop the frag late.
*/
goto drop_fragment;
}
pass:
/* Update maximum data size */
if ((*frag)->fr_max < max)
(*frag)->fr_max = max;
/* This is the last segment */
if (!mff)
(*frag)->fr_flags |= PFFRAG_SEENLAST;
/* Check if we are completely reassembled */
if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
LIST_FIRST(&(*frag)->fr_queue)->fr_off == 0 &&
LIST_FIRST(&(*frag)->fr_queue)->fr_end == (*frag)->fr_max) {
/* Remove from fragment queue */
DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
(*frag)->fr_max));
pf_free_fragment(*frag);
*frag = NULL;
}
return (m);
no_mem:
*nomem = 1;
/* Still need to pay attention to !IP_MF */
if (!mff && *frag != NULL)
(*frag)->fr_flags |= PFFRAG_SEENLAST;
m_freem(m);
return (NULL);
drop_fragment:
/* Still need to pay attention to !IP_MF */
if (!mff && *frag != NULL)
(*frag)->fr_flags |= PFFRAG_SEENLAST;
if (drop) {
/* This fragment has been deemed bad. Don't reass */
if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
h->ip_id));
(*frag)->fr_flags |= PFFRAG_DROP;
}
m_freem(m);
return (NULL);
}
int
pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
struct pf_pdesc *pd)
{
struct mbuf *m = *m0;
struct pf_rule *r;
struct pf_frent *frent;
struct pf_fragment *frag = NULL;
struct ip *h = mtod(m, struct ip *);
int mff = (ntohs(h->ip_off) & IP_MF);
int hlen = h->ip_hl << 2;
u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
u_int16_t max;
int ip_len;
int ip_off;
int tag = -1;
PF_RULES_RASSERT();
r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
while (r != NULL) {
r->evaluations++;
if (pfi_kif_match(r->kif, kif) == r->ifnot)
r = r->skip[PF_SKIP_IFP].ptr;
else if (r->direction && r->direction != dir)
r = r->skip[PF_SKIP_DIR].ptr;
else if (r->af && r->af != AF_INET)
r = r->skip[PF_SKIP_AF].ptr;
else if (r->proto && r->proto != h->ip_p)
r = r->skip[PF_SKIP_PROTO].ptr;
else if (PF_MISMATCHAW(&r->src.addr,
(struct pf_addr *)&h->ip_src.s_addr, AF_INET,
r->src.neg, kif, M_GETFIB(m)))
r = r->skip[PF_SKIP_SRC_ADDR].ptr;
else if (PF_MISMATCHAW(&r->dst.addr,
(struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
r->dst.neg, NULL, M_GETFIB(m)))
r = r->skip[PF_SKIP_DST_ADDR].ptr;
else if (r->match_tag && !pf_match_tag(m, r, &tag,
pd->pf_mtag ? pd->pf_mtag->tag : 0))
r = TAILQ_NEXT(r, entries);
else
break;
}
if (r == NULL || r->action == PF_NOSCRUB)
return (PF_PASS);
else {
r->packets[dir == PF_OUT]++;
r->bytes[dir == PF_OUT] += pd->tot_len;
}
/* Check for illegal packets */
if (hlen < (int)sizeof(struct ip))
goto drop;
if (hlen > ntohs(h->ip_len))
goto drop;
/* Clear IP_DF if the rule uses the no-df option */
if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
u_int16_t ip_off = h->ip_off;
h->ip_off &= htons(~IP_DF);
h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
}
/* We will need other tests here */
if (!fragoff && !mff)
goto no_fragment;
/* We're dealing with a fragment now. Don't allow fragments
* with IP_DF to enter the cache. If the flag was cleared by
* no-df above, fine. Otherwise drop it.
*/
if (h->ip_off & htons(IP_DF)) {
DPFPRINTF(("IP_DF\n"));
goto bad;
}
ip_len = ntohs(h->ip_len) - hlen;
ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
/* All fragments are 8 byte aligned */
if (mff && (ip_len & 0x7)) {
DPFPRINTF(("mff and %d\n", ip_len));
goto bad;
}
/* Respect maximum length */
if (fragoff + ip_len > IP_MAXPACKET) {
DPFPRINTF(("max packet %d\n", fragoff + ip_len));
goto bad;
}
max = fragoff + ip_len;
if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
/* Fully buffer all of the fragments */
PF_FRAG_LOCK();
frag = pf_find_fragment(h, &V_pf_frag_tree);
/* Check if we saw the last fragment already */
if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
max > frag->fr_max)
goto bad;
/* Get an entry for the fragment queue */
frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
if (frent == NULL) {
PF_FRAG_UNLOCK();
REASON_SET(reason, PFRES_MEMORY);
return (PF_DROP);
}
frent->fr_ip = h;
frent->fr_m = m;
/* Might return a completely reassembled mbuf, or NULL */
DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
*m0 = m = pf_reassemble(m0, &frag, frent, mff);
PF_FRAG_UNLOCK();
if (m == NULL)
return (PF_DROP);
if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
goto drop;
h = mtod(m, struct ip *);
} else {
/* non-buffering fragment cache (drops or masks overlaps) */
int nomem = 0;
if (dir == PF_OUT && pd->pf_mtag &&
pd->pf_mtag->flags & PF_TAG_FRAGCACHE) {
/*
* Already passed the fragment cache in the
* input direction. If we continued, it would
* appear to be a dup and would be dropped.