diff options
Diffstat (limited to 'sys/contrib/pf/net/pf_norm.c')
| -rw-r--r-- | sys/contrib/pf/net/pf_norm.c | 2023 |
1 files changed, 2023 insertions, 0 deletions
diff --git a/sys/contrib/pf/net/pf_norm.c b/sys/contrib/pf/net/pf_norm.c new file mode 100644 index 0000000..98ed5fb --- /dev/null +++ b/sys/contrib/pf/net/pf_norm.c @@ -0,0 +1,2023 @@ +/* $FreeBSD$ */ +/* $OpenBSD: pf_norm.c,v 1.97 2004/09/21 16:59:12 aaron Exp $ */ +/* add: $OpenBSD: pf_norm.c,v 1.106 2006/03/25 20:55:24 dhartmei Exp $ */ + +/* + * 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. + */ + +#ifdef __FreeBSD__ +#include "opt_inet.h" +#include "opt_inet6.h" +#include "opt_pf.h" +#ifdef DEV_PFLOG +#define NPFLOG DEV_PFLOG +#else +#define NPFLOG 0 +#endif +#else +#include "pflog.h" +#endif + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/mbuf.h> +#include <sys/filio.h> +#include <sys/fcntl.h> +#include <sys/socket.h> +#include <sys/kernel.h> +#include <sys/time.h> +#ifndef __FreeBSD__ +#include <sys/pool.h> + +#include <dev/rndvar.h> +#endif +#include <net/if.h> +#include <net/if_types.h> +#include <net/bpf.h> +#include <net/route.h> +#include <net/if_pflog.h> + +#include <netinet/in.h> +#include <netinet/in_var.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet/tcp.h> +#include <netinet/tcp_seq.h> +#include <netinet/udp.h> +#include <netinet/ip_icmp.h> + +#ifdef INET6 +#include <netinet/ip6.h> +#endif /* INET6 */ + +#include <net/pfvar.h> + +#ifndef __FreeBSD__ +#include <inttypes.h> + +struct pf_frent { + LIST_ENTRY(pf_frent) fr_next; + struct ip *fr_ip; + struct mbuf *fr_m; +}; + +struct pf_frcache { + LIST_ENTRY(pf_frcache) fr_next; + uint16_t fr_off; + uint16_t fr_end; +}; +#endif + +#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)) + +#ifndef __FreeBSD__ +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 */ + u_int16_t fr_id; /* fragment id for reassemble */ + u_int16_t fr_max; /* fragment data max */ + u_int32_t fr_timeout; +#define fr_queue fr_u.fru_queue +#define fr_cache fr_u.fru_cache + union { + LIST_HEAD(pf_fragq, pf_frent) fru_queue; /* buffering */ + LIST_HEAD(pf_cacheq, pf_frcache) fru_cache; /* non-buf */ + } fr_u; +}; +#endif + +TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue; +TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue; + +#ifndef __FreeBSD__ +static __inline int pf_frag_compare(struct pf_fragment *, + struct pf_fragment *); +#else +static int pf_frag_compare(struct pf_fragment *, + struct pf_fragment *); +#endif +RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree, pf_cache_tree; +RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); +RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); + +/* Private prototypes */ +void pf_ip2key(struct pf_fragment *, struct ip *); +void pf_remove_fragment(struct pf_fragment *); +void pf_flush_fragments(void); +void pf_free_fragment(struct pf_fragment *); +struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *); +struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **, + struct pf_frent *, int); +struct mbuf *pf_fragcache(struct mbuf **, struct ip*, + struct pf_fragment **, int, int, int *); +int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, + struct tcphdr *, int); + +#define DPFPRINTF(x) do { \ + if (pf_status.debug >= PF_DEBUG_MISC) { \ + printf("%s: ", __func__); \ + printf x ; \ + } \ +} while(0) + +/* Globals */ +#ifdef __FreeBSD__ +uma_zone_t pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl; +uma_zone_t pf_state_scrub_pl; +#else +struct pool pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl; +struct pool pf_state_scrub_pl; +#endif +int pf_nfrents, pf_ncache; + +void +pf_normalize_init(void) +{ +#ifdef __FreeBSD__ + /* + * XXX + * No high water mark support(It's hint not hard limit). + * uma_zone_set_max(pf_frag_pl, PFFRAG_FRAG_HIWAT); + */ + uma_zone_set_max(pf_frent_pl, PFFRAG_FRENT_HIWAT); + uma_zone_set_max(pf_cache_pl, PFFRAG_FRCACHE_HIWAT); + uma_zone_set_max(pf_cent_pl, PFFRAG_FRCENT_HIWAT); +#else + pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent", + NULL); + pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag", + NULL); + pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0, + "pffrcache", NULL); + pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent", + NULL); + pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0, + "pfstscr", NULL); + + pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT); + pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0); + pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0); + pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0); +#endif + + TAILQ_INIT(&pf_fragqueue); + TAILQ_INIT(&pf_cachequeue); +} + +#ifdef __FreeBSD__ +static int +#else +static __inline int +#endif +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_second - + pf_default_rule.timeout[PFTM_FRAG]; + + while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) { +#ifdef __FreeBSD__ + KASSERT((BUFFER_FRAGMENTS(frag)), + ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__)); +#else + KASSERT(BUFFER_FRAGMENTS(frag)); +#endif + if (frag->fr_timeout > expire) + break; + + DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); + pf_free_fragment(frag); + } + + while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) { +#ifdef __FreeBSD__ + KASSERT((!BUFFER_FRAGMENTS(frag)), + ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__)); +#else + KASSERT(!BUFFER_FRAGMENTS(frag)); +#endif + if (frag->fr_timeout > expire) + break; + + DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); + pf_free_fragment(frag); +#ifdef __FreeBSD__ + KASSERT((TAILQ_EMPTY(&pf_cachequeue) || + TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag), + ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", + __FUNCTION__)); +#else + KASSERT(TAILQ_EMPTY(&pf_cachequeue) || + TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag); +#endif + } +} + +/* + * Try to flush old fragments to make space for new ones + */ + +void +pf_flush_fragments(void) +{ + struct pf_fragment *frag; + int goal; + + goal = pf_nfrents * 9 / 10; + DPFPRINTF(("trying to free > %d frents\n", + pf_nfrents - goal)); + while (goal < pf_nfrents) { + frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue); + if (frag == NULL) + break; + pf_free_fragment(frag); + } + + + goal = pf_ncache * 9 / 10; + DPFPRINTF(("trying to free > %d cache entries\n", + pf_ncache - goal)); + while (goal < pf_ncache) { + frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue); + if (frag == NULL) + break; + pf_free_fragment(frag); + } +} + +/* Frees the fragments and all associated entries */ + +void +pf_free_fragment(struct pf_fragment *frag) +{ + struct pf_frent *frent; + struct pf_frcache *frcache; + + /* 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); + pool_put(&pf_frent_pl, frent); + pf_nfrents--; + } + } else { + for (frcache = LIST_FIRST(&frag->fr_cache); frcache; + frcache = LIST_FIRST(&frag->fr_cache)) { + LIST_REMOVE(frcache, fr_next); + +#ifdef __FreeBSD__ + KASSERT((LIST_EMPTY(&frag->fr_cache) || + LIST_FIRST(&frag->fr_cache)->fr_off > + frcache->fr_end), + ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >" + " frcache->fr_end): %s", __FUNCTION__)); +#else + KASSERT(LIST_EMPTY(&frag->fr_cache) || + LIST_FIRST(&frag->fr_cache)->fr_off > + frcache->fr_end); +#endif + + pool_put(&pf_cent_pl, frcache); + pf_ncache--; + } + } + + pf_remove_fragment(frag); +} + +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; +} + +struct pf_fragment * +pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree) +{ + struct pf_fragment key; + struct pf_fragment *frag; + + 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_second; + if (BUFFER_FRAGMENTS(frag)) { + TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); + TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next); + } else { + TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); + TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next); + } + } + + return (frag); +} + +/* Removes a fragment from the fragment queue and frees the fragment */ + +void +pf_remove_fragment(struct pf_fragment *frag) +{ + if (BUFFER_FRAGMENTS(frag)) { + RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag); + TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); + pool_put(&pf_frag_pl, frag); + } else { + RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag); + TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); + pool_put(&pf_cache_pl, frag); + } +} + +#define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3) +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; + +#ifdef __FreeBSD__ + KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)), + ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); +#else + KASSERT(*frag == NULL || BUFFER_FRAGMENTS(*frag)); +#endif + + /* Strip off ip header */ + m->m_data += hlen; + m->m_len -= hlen; + + /* Create a new reassembly queue for this packet */ + if (*frag == NULL) { + *frag = pool_get(&pf_frag_pl, PR_NOWAIT); + if (*frag == NULL) { + pf_flush_fragments(); + *frag = pool_get(&pf_frag_pl, PR_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_second; + LIST_INIT(&(*frag)->fr_queue); + + RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag); + TAILQ_INSERT_HEAD(&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; + } + +#ifdef __FreeBSD__ + KASSERT((frep != NULL || frea != NULL), + ("!(frep != NULL || frea != NULL): %s", __FUNCTION__));; +#else + KASSERT(frep != NULL || frea != NULL); +#endif + + 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, loose it */ + next = LIST_NEXT(frea, fr_next); + m_freem(frea->fr_m); + LIST_REMOVE(frea, fr_next); + pool_put(&pf_frent_pl, frea); + pf_nfrents--; + } + + 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); +#ifdef __FreeBSD__ + KASSERT((frent != NULL), ("frent == NULL: %s", __FUNCTION__)); +#else + KASSERT(frent != NULL); +#endif + 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); + pool_put(&pf_frent_pl, frent); + pf_nfrents--; + for (frent = next; frent != NULL; frent = next) { + next = LIST_NEXT(frent, fr_next); + + m2 = frent->fr_m; + pool_put(&pf_frent_pl, frent); + pf_nfrents--; + m_cat(m, m2); + } + + 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 */ + pool_put(&pf_frent_pl, frent); + pf_nfrents--; + m_freem(m); + return (NULL); +} + +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_frcache *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; + +#ifdef __FreeBSD__ + KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), + ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); +#else + KASSERT(*frag == NULL || !BUFFER_FRAGMENTS(*frag)); +#endif + + /* Create a new range queue for this packet */ + if (*frag == NULL) { + *frag = pool_get(&pf_cache_pl, PR_NOWAIT); + if (*frag == NULL) { + pf_flush_fragments(); + *frag = pool_get(&pf_cache_pl, PR_NOWAIT); + if (*frag == NULL) + goto no_mem; + } + + /* Get an entry for the queue */ + cur = pool_get(&pf_cent_pl, PR_NOWAIT); + if (cur == NULL) { + pool_put(&pf_cache_pl, *frag); + *frag = NULL; + goto no_mem; + } + pf_ncache++; + + (*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_second; + + cur->fr_off = off; + cur->fr_end = max; + LIST_INIT(&(*frag)->fr_cache); + LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); + + RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag); + TAILQ_INSERT_HEAD(&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_cache, fr_next) { + if (fra->fr_off > off) + break; + frp = fra; + } + +#ifdef __FreeBSD__ + KASSERT((frp != NULL || fra != NULL), + ("!(frp != NULL || fra != NULL): %s", __FUNCTION__)); +#else + KASSERT(frp != NULL || fra != NULL); +#endif + + 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. + */ +#ifdef __FreeBSD__ + *m0 = m_dup(m, M_DONTWAIT); +#else + *m0 = m_copym2(m, 0, h->ip_hl << 2, M_NOWAIT); +#endif + if (*m0 == NULL) + goto no_mem; +#ifdef __FreeBSD__ + /* 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__)); +#else + KASSERT((*m0)->m_next == NULL); +#endif + 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 *); + +#ifdef __FreeBSD__ + KASSERT(((int)m->m_len == + ntohs(h->ip_len) - precut), + ("m->m_len != ntohs(h->ip_len) - precut: %s", + __FUNCTION__)); +#else + KASSERT((int)m->m_len == + ntohs(h->ip_len) - precut); +#endif + 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 = pool_get(&pf_cent_pl, PR_NOWAIT); + if (cur == NULL) + goto no_mem; + pf_ncache++; + + 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 *); +#ifdef __FreeBSD__ + KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut), + ("m->m_len != ntohs(h->ip_len) - aftercut: %s", + __FUNCTION__)); +#else + KASSERT((int)m->m_len == + ntohs(h->ip_len) - aftercut); +#endif + 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 = pool_get(&pf_cent_pl, PR_NOWAIT); + if (cur == NULL) + goto no_mem; + pf_ncache++; + + 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); + pool_put(&pf_cent_pl, cur); + pf_ncache--; + cur = NULL; + + } else if (frp && fra->fr_off <= frp->fr_end) { + /* Need to merge in a modified 'frp' */ +#ifdef __FreeBSD__ + KASSERT((cur == NULL), ("cur != NULL: %s", + __FUNCTION__)); +#else + KASSERT(cur == NULL); +#endif + 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); + pool_put(&pf_cent_pl, frp); + pf_ncache--; + 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_cache)->fr_off == 0 && + LIST_FIRST(&(*frag)->fr_cache)->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; + + r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); + while (r != NULL) { + r->evaluations++; + if (r->kif != NULL && + (r->kif != kif && r->kif != kif->pfik_parent) == !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)) + 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)) + r = r->skip[PF_SKIP_DST_ADDR].ptr; + else + break; + } + + if (r == NULL) + return (PF_PASS); + else + r->packets++; + + /* 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 */ + + frag = pf_find_fragment(h, &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 = pool_get(&pf_frent_pl, PR_NOWAIT); + if (frent == NULL) { + REASON_SET(reason, PFRES_MEMORY); + return (PF_DROP); + } + pf_nfrents++; + 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); + + 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) { + if (m_tag_find(m, PACKET_TAG_PF_FRAGCACHE, NULL) != + NULL) { + /* Already passed the fragment cache in the + * input direction. If we continued, it would + * appear to be a dup and would be dropped. + */ + goto fragment_pass; + } + } + + frag = pf_find_fragment(h, &pf_cache_tree); + + /* Check if we saw the last fragment already */ + if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && + max > frag->fr_max) { + if (r->rule_flag & PFRULE_FRAGDROP) + frag->fr_flags |= PFFRAG_DROP; + goto bad; + } + + *m0 = m = pf_fragcache(m0, h, &frag, mff, + (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); + if (m == NULL) { + if (nomem) + goto no_mem; + goto drop; + } + + if (dir == PF_IN) { + struct m_tag *mtag; + + mtag = m_tag_get(PACKET_TAG_PF_FRAGCACHE, 0, M_NOWAIT); + if (mtag == NULL) + goto no_mem; + m_tag_prepend(m, mtag); + } + if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) + goto drop; + goto fragment_pass; + } + + no_fragment: + /* At this point, only IP_DF is allowed in ip_off */ + if (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); + } + + /* Enforce a minimum ttl, may cause endless packet loops */ + if (r->min_ttl && h->ip_ttl < r->min_ttl) { + u_int16_t ip_ttl = h->ip_ttl; + + h->ip_ttl = r->min_ttl; + h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); + } + + if (r->rule_flag & PFRULE_RANDOMID) { + u_int16_t ip_id = h->ip_id; + + h->ip_id = ip_randomid(); + h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); + } + if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) + pd->flags |= PFDESC_IP_REAS; + + return (PF_PASS); + + fragment_pass: + /* Enforce a minimum ttl, may cause endless packet loops */ + if (r->min_ttl && h->ip_ttl < r->min_ttl) { + u_int16_t ip_ttl = h->ip_ttl; + + h->ip_ttl = r->min_ttl; + h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); + } + if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) + pd->flags |= PFDESC_IP_REAS; + return (PF_PASS); + + no_mem: + REASON_SET(reason, PFRES_MEMORY); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); + return (PF_DROP); + + drop: + REASON_SET(reason, PFRES_NORM); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); + return (PF_DROP); + + bad: + DPFPRINTF(("dropping bad fragment\n")); + + /* Free associated fragments */ + if (frag != NULL) + pf_free_fragment(frag); + + REASON_SET(reason, PFRES_FRAG); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); + + return (PF_DROP); +} + +#ifdef INET6 +int +pf_normalize_ip6(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 ip6_hdr *h = mtod(m, struct ip6_hdr *); + int off; + struct ip6_ext ext; + struct ip6_opt opt; + struct ip6_opt_jumbo jumbo; + struct ip6_frag frag; + u_int32_t jumbolen = 0, plen; + u_int16_t fragoff = 0; + int optend; + int ooff; + u_int8_t proto; + int terminal; + + r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); + while (r != NULL) { + r->evaluations++; + if (r->kif != NULL && + (r->kif != kif && r->kif != kif->pfik_parent) == !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_INET6) + r = r->skip[PF_SKIP_AF].ptr; +#if 0 /* header chain! */ + else if (r->proto && r->proto != h->ip6_nxt) + r = r->skip[PF_SKIP_PROTO].ptr; +#endif + else if (PF_MISMATCHAW(&r->src.addr, + (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.neg)) + r = r->skip[PF_SKIP_SRC_ADDR].ptr; + else if (PF_MISMATCHAW(&r->dst.addr, + (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.neg)) + r = r->skip[PF_SKIP_DST_ADDR].ptr; + else + break; + } + + if (r == NULL) + return (PF_PASS); + else + r->packets++; + + /* Check for illegal packets */ + if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) + goto drop; + + off = sizeof(struct ip6_hdr); + proto = h->ip6_nxt; + terminal = 0; + do { + switch (proto) { + case IPPROTO_FRAGMENT: + goto fragment; + break; + case IPPROTO_AH: + case IPPROTO_ROUTING: + case IPPROTO_DSTOPTS: + if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, + NULL, AF_INET6)) + goto shortpkt; + if (proto == IPPROTO_AH) + off += (ext.ip6e_len + 2) * 4; + else + off += (ext.ip6e_len + 1) * 8; + proto = ext.ip6e_nxt; + break; + case IPPROTO_HOPOPTS: + if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, + NULL, AF_INET6)) + goto shortpkt; + optend = off + (ext.ip6e_len + 1) * 8; + ooff = off + sizeof(ext); + do { + if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, + sizeof(opt.ip6o_type), NULL, NULL, + AF_INET6)) + goto shortpkt; + if (opt.ip6o_type == IP6OPT_PAD1) { + ooff++; + continue; + } + if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), + NULL, NULL, AF_INET6)) + goto shortpkt; + if (ooff + sizeof(opt) + opt.ip6o_len > optend) + goto drop; + switch (opt.ip6o_type) { + case IP6OPT_JUMBO: + if (h->ip6_plen != 0) + goto drop; + if (!pf_pull_hdr(m, ooff, &jumbo, + sizeof(jumbo), NULL, NULL, + AF_INET6)) + goto shortpkt; + memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, + sizeof(jumbolen)); + jumbolen = ntohl(jumbolen); + if (jumbolen <= IPV6_MAXPACKET) + goto drop; + if (sizeof(struct ip6_hdr) + jumbolen != + m->m_pkthdr.len) + goto drop; + break; + default: + break; + } + ooff += sizeof(opt) + opt.ip6o_len; + } while (ooff < optend); + + off = optend; + proto = ext.ip6e_nxt; + break; + default: + terminal = 1; + break; + } + } while (!terminal); + + /* jumbo payload option must be present, or plen > 0 */ + if (ntohs(h->ip6_plen) == 0) + plen = jumbolen; + else + plen = ntohs(h->ip6_plen); + if (plen == 0) + goto drop; + if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) + goto shortpkt; + + /* Enforce a minimum ttl, may cause endless packet loops */ + if (r->min_ttl && h->ip6_hlim < r->min_ttl) + h->ip6_hlim = r->min_ttl; + + return (PF_PASS); + + fragment: + if (ntohs(h->ip6_plen) == 0 || jumbolen) + goto drop; + plen = ntohs(h->ip6_plen); + + if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) + goto shortpkt; + fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK); + if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET) + goto badfrag; + + /* do something about it */ + /* remember to set pd->flags |= PFDESC_IP_REAS */ + return (PF_PASS); + + shortpkt: + REASON_SET(reason, PFRES_SHORT); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); + return (PF_DROP); + + drop: + REASON_SET(reason, PFRES_NORM); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); + return (PF_DROP); + + badfrag: + REASON_SET(reason, PFRES_FRAG); + if (r != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); + return (PF_DROP); +} +#endif /* INET6 */ + +int +pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, + int off, void *h, struct pf_pdesc *pd) +{ + struct pf_rule *r, *rm = NULL; + struct tcphdr *th = pd->hdr.tcp; + int rewrite = 0; + u_short reason; + u_int8_t flags; + sa_family_t af = pd->af; + + r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); + while (r != NULL) { + r->evaluations++; + if (r->kif != NULL && + (r->kif != kif && r->kif != kif->pfik_parent) == !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) + r = r->skip[PF_SKIP_AF].ptr; + else if (r->proto && r->proto != pd->proto) + r = r->skip[PF_SKIP_PROTO].ptr; + else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.neg)) + r = r->skip[PF_SKIP_SRC_ADDR].ptr; + else if (r->src.port_op && !pf_match_port(r->src.port_op, + r->src.port[0], r->src.port[1], th->th_sport)) + r = r->skip[PF_SKIP_SRC_PORT].ptr; + else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, r->dst.neg)) + r = r->skip[PF_SKIP_DST_ADDR].ptr; + else if (r->dst.port_op && !pf_match_port(r->dst.port_op, + r->dst.port[0], r->dst.port[1], th->th_dport)) + r = r->skip[PF_SKIP_DST_PORT].ptr; + else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( + pf_osfp_fingerprint(pd, m, off, th), + r->os_fingerprint)) + r = TAILQ_NEXT(r, entries); + else { + rm = r; + break; + } + } + + if (rm == NULL || rm->action == PF_NOSCRUB) + return (PF_PASS); + else + r->packets++; + + if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) + pd->flags |= PFDESC_TCP_NORM; + + flags = th->th_flags; + if (flags & TH_SYN) { + /* Illegal packet */ + if (flags & TH_RST) + goto tcp_drop; + + if (flags & TH_FIN) + flags &= ~TH_FIN; + } else { + /* Illegal packet */ + if (!(flags & (TH_ACK|TH_RST))) + goto tcp_drop; + } + + if (!(flags & TH_ACK)) { + /* These flags are only valid if ACK is set */ + if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) + goto tcp_drop; + } + + /* Check for illegal header length */ + if (th->th_off < (sizeof(struct tcphdr) >> 2)) + goto tcp_drop; + + /* If flags changed, or reserved data set, then adjust */ + if (flags != th->th_flags || th->th_x2 != 0) { + u_int16_t ov, nv; + + ov = *(u_int16_t *)(&th->th_ack + 1); + th->th_flags = flags; + th->th_x2 = 0; + nv = *(u_int16_t *)(&th->th_ack + 1); + + th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); + rewrite = 1; + } + + /* Remove urgent pointer, if TH_URG is not set */ + if (!(flags & TH_URG) && th->th_urp) { + th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); + th->th_urp = 0; + rewrite = 1; + } + + /* Process options */ + if (r->max_mss && pf_normalize_tcpopt(r, m, th, off)) + rewrite = 1; + + /* copy back packet headers if we sanitized */ + if (rewrite) + m_copyback(m, off, sizeof(*th), (caddr_t)th); + + return (PF_PASS); + + tcp_drop: + REASON_SET(&reason, PFRES_NORM); + if (rm != NULL && r->log) + PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL); + return (PF_DROP); +} + +int +pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, + struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) +{ + u_int32_t tsval, tsecr; + u_int8_t hdr[60]; + u_int8_t *opt; + +#ifdef __FreeBSD__ + KASSERT((src->scrub == NULL), + ("pf_normalize_tcp_init: src->scrub != NULL")); +#else + KASSERT(src->scrub == NULL); +#endif + + src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT); + if (src->scrub == NULL) + return (1); + bzero(src->scrub, sizeof(*src->scrub)); + + switch (pd->af) { +#ifdef INET + case AF_INET: { + struct ip *h = mtod(m, struct ip *); + src->scrub->pfss_ttl = h->ip_ttl; + break; + } +#endif /* INET */ +#ifdef INET6 + case AF_INET6: { + struct ip6_hdr *h = mtod(m, struct ip6_hdr *); + src->scrub->pfss_ttl = h->ip6_hlim; + break; + } +#endif /* INET6 */ + } + + + /* + * All normalizations below are only begun if we see the start of + * the connections. They must all set an enabled bit in pfss_flags + */ + if ((th->th_flags & TH_SYN) == 0) + return (0); + + + if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && + pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { + /* Diddle with TCP options */ + int hlen; + opt = hdr + sizeof(struct tcphdr); + hlen = (th->th_off << 2) - sizeof(struct tcphdr); + while (hlen >= TCPOLEN_TIMESTAMP) { + switch (*opt) { + case TCPOPT_EOL: /* FALLTHROUGH */ + case TCPOPT_NOP: + opt++; + hlen--; + break; + case TCPOPT_TIMESTAMP: + if (opt[1] >= TCPOLEN_TIMESTAMP) { + src->scrub->pfss_flags |= + PFSS_TIMESTAMP; + src->scrub->pfss_ts_mod = + htonl(arc4random()); + + /* note PFSS_PAWS not set yet */ + memcpy(&tsval, &opt[2], + sizeof(u_int32_t)); + memcpy(&tsecr, &opt[6], + sizeof(u_int32_t)); + src->scrub->pfss_tsval0 = ntohl(tsval); + src->scrub->pfss_tsval = ntohl(tsval); + src->scrub->pfss_tsecr = ntohl(tsecr); + getmicrouptime(&src->scrub->pfss_last); + } + /* FALLTHROUGH */ + default: + hlen -= MAX(opt[1], 2); + opt += MAX(opt[1], 2); + break; + } + } + } + + return (0); +} + +void +pf_normalize_tcp_cleanup(struct pf_state *state) +{ + if (state->src.scrub) + pool_put(&pf_state_scrub_pl, state->src.scrub); + if (state->dst.scrub) + pool_put(&pf_state_scrub_pl, state->dst.scrub); + + /* Someday... flush the TCP segment reassembly descriptors. */ +} + +int +pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, + u_short *reason, struct tcphdr *th, struct pf_state *state, + struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) +{ + struct timeval uptime; + u_int32_t tsval, tsecr; + u_int tsval_from_last; + u_int8_t hdr[60]; + u_int8_t *opt; + int copyback = 0; + int got_ts = 0; + +#ifdef __FreeBSD__ + KASSERT((src->scrub || dst->scrub), + ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!")); +#else + KASSERT(src->scrub || dst->scrub); +#endif + + /* + * Enforce the minimum TTL seen for this connection. Negate a common + * technique to evade an intrusion detection system and confuse + * firewall state code. + */ + switch (pd->af) { +#ifdef INET + case AF_INET: { + if (src->scrub) { + struct ip *h = mtod(m, struct ip *); + if (h->ip_ttl > src->scrub->pfss_ttl) + src->scrub->pfss_ttl = h->ip_ttl; + h->ip_ttl = src->scrub->pfss_ttl; + } + break; + } +#endif /* INET */ +#ifdef INET6 + case AF_INET6: { + if (src->scrub) { + struct ip6_hdr *h = mtod(m, struct ip6_hdr *); + if (h->ip6_hlim > src->scrub->pfss_ttl) + src->scrub->pfss_ttl = h->ip6_hlim; + h->ip6_hlim = src->scrub->pfss_ttl; + } + break; + } +#endif /* INET6 */ + } + + if (th->th_off > (sizeof(struct tcphdr) >> 2) && + ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || + (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && + pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { + /* Diddle with TCP options */ + int hlen; + opt = hdr + sizeof(struct tcphdr); + hlen = (th->th_off << 2) - sizeof(struct tcphdr); + while (hlen >= TCPOLEN_TIMESTAMP) { + switch (*opt) { + case TCPOPT_EOL: /* FALLTHROUGH */ + case TCPOPT_NOP: + opt++; + hlen--; + break; + case TCPOPT_TIMESTAMP: + /* Modulate the timestamps. Can be used for + * NAT detection, OS uptime determination or + * reboot detection. + */ + + if (got_ts) { + /* Huh? Multiple timestamps!? */ + if (pf_status.debug >= PF_DEBUG_MISC) { + DPFPRINTF(("multiple TS??")); + pf_print_state(state); + printf("\n"); + } + REASON_SET(reason, PFRES_TS); + return (PF_DROP); + } + if (opt[1] >= TCPOLEN_TIMESTAMP) { + memcpy(&tsval, &opt[2], + sizeof(u_int32_t)); + if (tsval && src->scrub && + (src->scrub->pfss_flags & + PFSS_TIMESTAMP)) { + tsval = ntohl(tsval); + pf_change_a(&opt[2], + &th->th_sum, + htonl(tsval + + src->scrub->pfss_ts_mod), + 0); + copyback = 1; + } + + /* Modulate TS reply iff valid (!0) */ + memcpy(&tsecr, &opt[6], + sizeof(u_int32_t)); + if (tsecr && dst->scrub && + (dst->scrub->pfss_flags & + PFSS_TIMESTAMP)) { + tsecr = ntohl(tsecr) + - dst->scrub->pfss_ts_mod; + pf_change_a(&opt[6], + &th->th_sum, htonl(tsecr), + 0); + copyback = 1; + } + got_ts = 1; + } + /* FALLTHROUGH */ + default: + hlen -= MAX(opt[1], 2); + opt += MAX(opt[1], 2); + break; + } + } + if (copyback) { + /* Copyback the options, caller copys back header */ + *writeback = 1; + m_copyback(m, off + sizeof(struct tcphdr), + (th->th_off << 2) - sizeof(struct tcphdr), hdr + + sizeof(struct tcphdr)); + } + } + + + /* + * Must invalidate PAWS checks on connections idle for too long. + * The fastest allowed timestamp clock is 1ms. That turns out to + * be about 24 days before it wraps. XXX Right now our lowerbound + * TS echo check only works for the first 12 days of a connection + * when the TS has exhausted half its 32bit space + */ +#define TS_MAX_IDLE (24*24*60*60) +#define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ + + getmicrouptime(&uptime); + if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && + (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || + time_second - state->creation > TS_MAX_CONN)) { + if (pf_status.debug >= PF_DEBUG_MISC) { + DPFPRINTF(("src idled out of PAWS\n")); + pf_print_state(state); + printf("\n"); + } + src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) + | PFSS_PAWS_IDLED; + } + if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && + uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { + if (pf_status.debug >= PF_DEBUG_MISC) { + DPFPRINTF(("dst idled out of PAWS\n")); + pf_print_state(state); + printf("\n"); + } + dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) + | PFSS_PAWS_IDLED; + } + + if (got_ts && src->scrub && dst->scrub && + (src->scrub->pfss_flags & PFSS_PAWS) && + (dst->scrub->pfss_flags & PFSS_PAWS)) { + /* Validate that the timestamps are "in-window". + * RFC1323 describes TCP Timestamp options that allow + * measurement of RTT (round trip time) and PAWS + * (protection against wrapped sequence numbers). PAWS + * gives us a set of rules for rejecting packets on + * long fat pipes (packets that were somehow delayed + * in transit longer than the time it took to send the + * full TCP sequence space of 4Gb). We can use these + * rules and infer a few others that will let us treat + * the 32bit timestamp and the 32bit echoed timestamp + * as sequence numbers to prevent a blind attacker from + * inserting packets into a connection. + * + * RFC1323 tells us: + * - The timestamp on this packet must be greater than + * or equal to the last value echoed by the other + * endpoint. The RFC says those will be discarded + * since it is a dup that has already been acked. + * This gives us a lowerbound on the timestamp. + * timestamp >= other last echoed timestamp + * - The timestamp will be less than or equal to + * the last timestamp plus the time between the + * last packet and now. The RFC defines the max + * clock rate as 1ms. We will allow clocks to be + * up to 10% fast and will allow a total difference + * or 30 seconds due to a route change. And this + * gives us an upperbound on the timestamp. + * timestamp <= last timestamp + max ticks + * We have to be careful here. Windows will send an + * initial timestamp of zero and then initialize it + * to a random value after the 3whs; presumably to + * avoid a DoS by having to call an expensive RNG + * during a SYN flood. Proof MS has at least one + * good security geek. + * + * - The TCP timestamp option must also echo the other + * endpoints timestamp. The timestamp echoed is the + * one carried on the earliest unacknowledged segment + * on the left edge of the sequence window. The RFC + * states that the host will reject any echoed + * timestamps that were larger than any ever sent. + * This gives us an upperbound on the TS echo. + * tescr <= largest_tsval + * - The lowerbound on the TS echo is a little more + * tricky to determine. The other endpoint's echoed + * values will not decrease. But there may be + * network conditions that re-order packets and + * cause our view of them to decrease. For now the + * only lowerbound we can safely determine is that + * the TS echo will never be less than the orginal + * TS. XXX There is probably a better lowerbound. + * Remove TS_MAX_CONN with better lowerbound check. + * tescr >= other original TS + * + * It is also important to note that the fastest + * timestamp clock of 1ms will wrap its 32bit space in + * 24 days. So we just disable TS checking after 24 + * days of idle time. We actually must use a 12d + * connection limit until we can come up with a better + * lowerbound to the TS echo check. + */ + struct timeval delta_ts; + int ts_fudge; + + + /* + * PFTM_TS_DIFF is how many seconds of leeway to allow + * a host's timestamp. This can happen if the previous + * packet got delayed in transit for much longer than + * this packet. + */ + if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) + ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF]; + + + /* Calculate max ticks since the last timestamp */ +#define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ +#define TS_MICROSECS 1000000 /* microseconds per second */ +#ifdef __FreeBSD__ +#ifndef timersub +#define timersub(tvp, uvp, vvp) \ + do { \ + (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec; \ + (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec; \ + if ((vvp)->tv_usec < 0) { \ + (vvp)->tv_sec--; \ + (vvp)->tv_usec += 1000000; \ + } \ + } while (0) +#endif +#endif + timersub(&uptime, &src->scrub->pfss_last, &delta_ts); + tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; + tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); + + + if ((src->state >= TCPS_ESTABLISHED && + dst->state >= TCPS_ESTABLISHED) && + (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || + SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || + (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || + SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { + /* Bad RFC1323 implementation or an insertion attack. + * + * - Solaris 2.6 and 2.7 are known to send another ACK + * after the FIN,FIN|ACK,ACK closing that carries + * an old timestamp. + */ + + DPFPRINTF(("Timestamp failed %c%c%c%c\n", + SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', + SEQ_GT(tsval, src->scrub->pfss_tsval + + tsval_from_last) ? '1' : ' ', + SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', + SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); +#ifdef __FreeBSD__ + DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " + "idle: %jus %lums\n", + tsval, tsecr, tsval_from_last, + (uintmax_t)delta_ts.tv_sec, + delta_ts.tv_usec / 1000)); + DPFPRINTF((" src->tsval: %u tsecr: %u\n", + src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); + DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" + "\n", dst->scrub->pfss_tsval, + dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); +#else + DPFPRINTF((" tsval: %lu tsecr: %lu +ticks: %lu " + "idle: %lus %lums\n", + tsval, tsecr, tsval_from_last, delta_ts.tv_sec, + delta_ts.tv_usec / 1000)); + DPFPRINTF((" src->tsval: %lu tsecr: %lu\n", + src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); + DPFPRINTF((" dst->tsval: %lu tsecr: %lu tsval0: %lu" + "\n", dst->scrub->pfss_tsval, + dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); +#endif + if (pf_status.debug >= PF_DEBUG_MISC) { + pf_print_state(state); + pf_print_flags(th->th_flags); + printf("\n"); + } + REASON_SET(reason, PFRES_TS); + return (PF_DROP); + } + + /* XXX I'd really like to require tsecr but it's optional */ + + } else if (!got_ts && (th->th_flags & TH_RST) == 0 && + ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) + || pd->p_len > 0 || (th->th_flags & TH_SYN)) && + src->scrub && dst->scrub && + (src->scrub->pfss_flags & PFSS_PAWS) && + (dst->scrub->pfss_flags & PFSS_PAWS)) { + /* Didn't send a timestamp. Timestamps aren't really useful + * when: + * - connection opening or closing (often not even sent). + * but we must not let an attacker to put a FIN on a + * data packet to sneak it through our ESTABLISHED check. + * - on a TCP reset. RFC suggests not even looking at TS. + * - on an empty ACK. The TS will not be echoed so it will + * probably not help keep the RTT calculation in sync and + * there isn't as much danger when the sequence numbers + * got wrapped. So some stacks don't include TS on empty + * ACKs :-( + * + * To minimize the disruption to mostly RFC1323 conformant + * stacks, we will only require timestamps on data packets. + * + * And what do ya know, we cannot require timestamps on data + * packets. There appear to be devices that do legitimate + * TCP connection hijacking. There are HTTP devices that allow + * a 3whs (with timestamps) and then buffer the HTTP request. + * If the intermediate device has the HTTP response cache, it + * will spoof the response but not bother timestamping its + * packets. So we can look for the presence of a timestamp in + * the first data packet and if there, require it in all future + * packets. + */ + + if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { + /* + * Hey! Someone tried to sneak a packet in. Or the + * stack changed its RFC1323 behavior?!?! + */ + if (pf_status.debug >= PF_DEBUG_MISC) { + DPFPRINTF(("Did not receive expected RFC1323 " + "timestamp\n")); + pf_print_state(state); + pf_print_flags(th->th_flags); + printf("\n"); + } + REASON_SET(reason, PFRES_TS); + return (PF_DROP); + } + } + + + /* + * We will note if a host sends his data packets with or without + * timestamps. And require all data packets to contain a timestamp + * if the first does. PAWS implicitly requires that all data packets be + * timestamped. But I think there are middle-man devices that hijack + * TCP streams immedietly after the 3whs and don't timestamp their + * packets (seen in a WWW accelerator or cache). + */ + if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & + (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { + if (got_ts) + src->scrub->pfss_flags |= PFSS_DATA_TS; + else { + src->scrub->pfss_flags |= PFSS_DATA_NOTS; + if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub && + (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { + /* Don't warn if other host rejected RFC1323 */ + DPFPRINTF(("Broken RFC1323 stack did not " + "timestamp data packet. Disabled PAWS " + "security.\n")); + pf_print_state(state); + pf_print_flags(th->th_flags); + printf("\n"); + } + } + } + + + /* + * Update PAWS values + */ + if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & + (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { + getmicrouptime(&src->scrub->pfss_last); + if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || + (src->scrub->pfss_flags & PFSS_PAWS) == 0) + src->scrub->pfss_tsval = tsval; + + if (tsecr) { + if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || + (src->scrub->pfss_flags & PFSS_PAWS) == 0) + src->scrub->pfss_tsecr = tsecr; + + if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && + (SEQ_LT(tsval, src->scrub->pfss_tsval0) || + src->scrub->pfss_tsval0 == 0)) { + /* tsval0 MUST be the lowest timestamp */ + src->scrub->pfss_tsval0 = tsval; + } + + /* Only fully initialized after a TS gets echoed */ + if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) + src->scrub->pfss_flags |= PFSS_PAWS; + } + } + + /* I have a dream.... TCP segment reassembly.... */ + return (0); +} + +int +pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, + int off) +{ + u_int16_t *mss; + int thoff; + int opt, cnt, optlen = 0; + int rewrite = 0; + u_char *optp; + + thoff = th->th_off << 2; + cnt = thoff - sizeof(struct tcphdr); + optp = mtod(m, caddr_t) + off + sizeof(struct tcphdr); + + for (; cnt > 0; cnt -= optlen, optp += optlen) { + opt = optp[0]; + if (opt == TCPOPT_EOL) + break; + if (opt == TCPOPT_NOP) + optlen = 1; + else { + if (cnt < 2) + break; + optlen = optp[1]; + if (optlen < 2 || optlen > cnt) + break; + } + switch (opt) { + case TCPOPT_MAXSEG: + mss = (u_int16_t *)(optp + 2); + if ((ntohs(*mss)) > r->max_mss) { + th->th_sum = pf_cksum_fixup(th->th_sum, + *mss, htons(r->max_mss), 0); + *mss = htons(r->max_mss); + rewrite = 1; + } + break; + default: + break; + } + } + + return (rewrite); +} |
