f287767d4f
Remove our (very partial) support for RFC2675 Jumbograms. They're not used, not actually supported and not a good idea. Reviewed by: thj@ Differential Revision: https://reviews.freebsd.org/D21086
2005 lines
55 KiB
C
2005 lines
55 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright 2001 Niels Provos <provos@citi.umich.edu>
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* Copyright 2011-2018 Alexander Bluhm <bluhm@openbsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_pf.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mbuf.h>
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#include <sys/mutex.h>
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#include <sys/refcount.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <net/vnet.h>
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#include <net/pfvar.h>
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#include <net/if_pflog.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet6/ip6_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#ifdef INET6
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#include <netinet/ip6.h>
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#endif /* INET6 */
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struct pf_frent {
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TAILQ_ENTRY(pf_frent) fr_next;
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struct mbuf *fe_m;
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uint16_t fe_hdrlen; /* ipv4 header length with ip options
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ipv6, extension, fragment header */
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uint16_t fe_extoff; /* last extension header offset or 0 */
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uint16_t fe_len; /* fragment length */
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uint16_t fe_off; /* fragment offset */
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uint16_t fe_mff; /* more fragment flag */
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};
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struct pf_fragment_cmp {
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struct pf_addr frc_src;
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struct pf_addr frc_dst;
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uint32_t frc_id;
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sa_family_t frc_af;
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uint8_t frc_proto;
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};
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struct pf_fragment {
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struct pf_fragment_cmp fr_key;
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#define fr_src fr_key.frc_src
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#define fr_dst fr_key.frc_dst
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#define fr_id fr_key.frc_id
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#define fr_af fr_key.frc_af
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#define fr_proto fr_key.frc_proto
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/* pointers to queue element */
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struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS];
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/* count entries between pointers */
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uint8_t fr_entries[PF_FRAG_ENTRY_POINTS];
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RB_ENTRY(pf_fragment) fr_entry;
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TAILQ_ENTRY(pf_fragment) frag_next;
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uint32_t fr_timeout;
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uint16_t fr_maxlen; /* maximum length of single fragment */
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u_int16_t fr_holes; /* number of holes in the queue */
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TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
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};
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struct pf_fragment_tag {
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uint16_t ft_hdrlen; /* header length of reassembled pkt */
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uint16_t ft_extoff; /* last extension header offset or 0 */
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uint16_t ft_maxlen; /* maximum fragment payload length */
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uint32_t ft_id; /* fragment id */
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};
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static struct mtx pf_frag_mtx;
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MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF);
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#define PF_FRAG_LOCK() mtx_lock(&pf_frag_mtx)
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#define PF_FRAG_UNLOCK() mtx_unlock(&pf_frag_mtx)
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#define PF_FRAG_ASSERT() mtx_assert(&pf_frag_mtx, MA_OWNED)
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VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */
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VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z);
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#define V_pf_frent_z VNET(pf_frent_z)
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VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z);
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#define V_pf_frag_z VNET(pf_frag_z)
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TAILQ_HEAD(pf_fragqueue, pf_fragment);
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TAILQ_HEAD(pf_cachequeue, pf_fragment);
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VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue);
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#define V_pf_fragqueue VNET(pf_fragqueue)
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RB_HEAD(pf_frag_tree, pf_fragment);
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VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree);
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#define V_pf_frag_tree VNET(pf_frag_tree)
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static int pf_frag_compare(struct pf_fragment *,
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struct pf_fragment *);
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static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
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static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
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static void pf_flush_fragments(void);
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static void pf_free_fragment(struct pf_fragment *);
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static void pf_remove_fragment(struct pf_fragment *);
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static int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
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struct tcphdr *, int, sa_family_t);
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static struct pf_frent *pf_create_fragment(u_short *);
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static int pf_frent_holes(struct pf_frent *frent);
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static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
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struct pf_frag_tree *tree);
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static inline int pf_frent_index(struct pf_frent *);
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static int pf_frent_insert(struct pf_fragment *,
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struct pf_frent *, struct pf_frent *);
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void pf_frent_remove(struct pf_fragment *,
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struct pf_frent *);
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struct pf_frent *pf_frent_previous(struct pf_fragment *,
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struct pf_frent *);
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static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
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struct pf_frent *, u_short *);
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static struct mbuf *pf_join_fragment(struct pf_fragment *);
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#ifdef INET
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static void pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t);
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static int pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
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#endif /* INET */
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#ifdef INET6
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static int pf_reassemble6(struct mbuf **, struct ip6_hdr *,
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struct ip6_frag *, uint16_t, uint16_t, u_short *);
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static void pf_scrub_ip6(struct mbuf **, uint8_t);
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#endif /* INET6 */
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#define DPFPRINTF(x) do { \
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if (V_pf_status.debug >= PF_DEBUG_MISC) { \
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printf("%s: ", __func__); \
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printf x ; \
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} \
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} while(0)
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#ifdef INET
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static void
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pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
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{
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key->frc_src.v4 = ip->ip_src;
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key->frc_dst.v4 = ip->ip_dst;
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key->frc_af = AF_INET;
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key->frc_proto = ip->ip_p;
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key->frc_id = ip->ip_id;
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}
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#endif /* INET */
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void
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pf_normalize_init(void)
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{
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V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
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V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
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V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
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sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL,
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UMA_ALIGN_PTR, 0);
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V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
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V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
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uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
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uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
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TAILQ_INIT(&V_pf_fragqueue);
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}
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void
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pf_normalize_cleanup(void)
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{
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uma_zdestroy(V_pf_state_scrub_z);
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uma_zdestroy(V_pf_frent_z);
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uma_zdestroy(V_pf_frag_z);
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}
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static int
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pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
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{
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int diff;
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if ((diff = a->fr_id - b->fr_id) != 0)
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return (diff);
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if ((diff = a->fr_proto - b->fr_proto) != 0)
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return (diff);
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if ((diff = a->fr_af - b->fr_af) != 0)
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return (diff);
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if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
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return (diff);
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if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
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return (diff);
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return (0);
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}
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void
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pf_purge_expired_fragments(void)
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{
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u_int32_t expire = time_uptime -
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V_pf_default_rule.timeout[PFTM_FRAG];
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pf_purge_fragments(expire);
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}
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void
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pf_purge_fragments(uint32_t expire)
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{
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struct pf_fragment *frag;
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PF_FRAG_LOCK();
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while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
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if (frag->fr_timeout > expire)
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break;
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DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
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pf_free_fragment(frag);
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}
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PF_FRAG_UNLOCK();
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}
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/*
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* Try to flush old fragments to make space for new ones
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*/
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static void
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pf_flush_fragments(void)
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{
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struct pf_fragment *frag;
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int goal;
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PF_FRAG_ASSERT();
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goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
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DPFPRINTF(("trying to free %d frag entriess\n", goal));
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while (goal < uma_zone_get_cur(V_pf_frent_z)) {
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frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
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if (frag)
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pf_free_fragment(frag);
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else
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break;
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}
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}
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/* Frees the fragments and all associated entries */
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static void
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pf_free_fragment(struct pf_fragment *frag)
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{
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struct pf_frent *frent;
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PF_FRAG_ASSERT();
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/* Free all fragments */
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for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
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frent = TAILQ_FIRST(&frag->fr_queue)) {
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TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
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m_freem(frent->fe_m);
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uma_zfree(V_pf_frent_z, frent);
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}
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pf_remove_fragment(frag);
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}
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static struct pf_fragment *
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pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
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{
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struct pf_fragment *frag;
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PF_FRAG_ASSERT();
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frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
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if (frag != NULL) {
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/* XXX Are we sure we want to update the timeout? */
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frag->fr_timeout = time_uptime;
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TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
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TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
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}
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return (frag);
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}
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/* Removes a fragment from the fragment queue and frees the fragment */
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static void
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pf_remove_fragment(struct pf_fragment *frag)
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{
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PF_FRAG_ASSERT();
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KASSERT(frag, ("frag != NULL"));
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RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
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TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
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uma_zfree(V_pf_frag_z, frag);
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}
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static struct pf_frent *
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pf_create_fragment(u_short *reason)
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{
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struct pf_frent *frent;
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PF_FRAG_ASSERT();
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frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
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if (frent == NULL) {
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pf_flush_fragments();
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frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
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if (frent == NULL) {
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REASON_SET(reason, PFRES_MEMORY);
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return (NULL);
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}
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}
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return (frent);
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}
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/*
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* Calculate the additional holes that were created in the fragment
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* queue by inserting this fragment. A fragment in the middle
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* creates one more hole by splitting. For each connected side,
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* it loses one hole.
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* Fragment entry must be in the queue when calling this function.
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*/
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static int
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pf_frent_holes(struct pf_frent *frent)
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{
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struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
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struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
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int holes = 1;
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if (prev == NULL) {
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if (frent->fe_off == 0)
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holes--;
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} else {
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KASSERT(frent->fe_off != 0, ("frent->fe_off != 0"));
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if (frent->fe_off == prev->fe_off + prev->fe_len)
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holes--;
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}
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if (next == NULL) {
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if (!frent->fe_mff)
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holes--;
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} else {
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KASSERT(frent->fe_mff, ("frent->fe_mff"));
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if (next->fe_off == frent->fe_off + frent->fe_len)
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holes--;
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}
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return holes;
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}
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static inline int
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pf_frent_index(struct pf_frent *frent)
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{
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/*
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* We have an array of 16 entry points to the queue. A full size
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* 65535 octet IP packet can have 8192 fragments. So the queue
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* traversal length is at most 512 and at most 16 entry points are
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* checked. We need 128 additional bytes on a 64 bit architecture.
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*/
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CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) ==
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16 - 1);
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CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1);
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return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS);
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}
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static int
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pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent,
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struct pf_frent *prev)
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{
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int index;
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CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff);
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/*
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* A packet has at most 65536 octets. With 16 entry points, each one
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* spawns 4096 octets. We limit these to 64 fragments each, which
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* means on average every fragment must have at least 64 octets.
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*/
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index = pf_frent_index(frent);
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if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT)
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return ENOBUFS;
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frag->fr_entries[index]++;
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if (prev == NULL) {
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TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
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} else {
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KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
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("overlapping fragment"));
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TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
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}
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if (frag->fr_firstoff[index] == NULL) {
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KASSERT(prev == NULL || pf_frent_index(prev) < index,
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("prev == NULL || pf_frent_index(pref) < index"));
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frag->fr_firstoff[index] = frent;
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} else {
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if (frent->fe_off < frag->fr_firstoff[index]->fe_off) {
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KASSERT(prev == NULL || pf_frent_index(prev) < index,
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("prev == NULL || pf_frent_index(pref) < index"));
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frag->fr_firstoff[index] = frent;
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} else {
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KASSERT(prev != NULL, ("prev != NULL"));
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KASSERT(pf_frent_index(prev) == index,
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("pf_frent_index(prev) == index"));
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}
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}
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frag->fr_holes += pf_frent_holes(frent);
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return 0;
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}
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void
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pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent)
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{
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#ifdef INVARIANTS
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struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
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#endif
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struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
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int index;
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frag->fr_holes -= pf_frent_holes(frent);
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index = pf_frent_index(frent);
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KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found"));
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if (frag->fr_firstoff[index]->fe_off == frent->fe_off) {
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if (next == NULL) {
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frag->fr_firstoff[index] = NULL;
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} else {
|
|
KASSERT(frent->fe_off + frent->fe_len <= next->fe_off,
|
|
("overlapping fragment"));
|
|
if (pf_frent_index(next) == index) {
|
|
frag->fr_firstoff[index] = next;
|
|
} else {
|
|
frag->fr_firstoff[index] = NULL;
|
|
}
|
|
}
|
|
} else {
|
|
KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off,
|
|
("frag->fr_firstoff[index]->fe_off < frent->fe_off"));
|
|
KASSERT(prev != NULL, ("prev != NULL"));
|
|
KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
|
|
("overlapping fragment"));
|
|
KASSERT(pf_frent_index(prev) == index,
|
|
("pf_frent_index(prev) == index"));
|
|
}
|
|
|
|
TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
|
|
|
|
KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining"));
|
|
frag->fr_entries[index]--;
|
|
}
|
|
|
|
struct pf_frent *
|
|
pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent)
|
|
{
|
|
struct pf_frent *prev, *next;
|
|
int index;
|
|
|
|
/*
|
|
* If there are no fragments after frag, take the final one. Assume
|
|
* that the global queue is not empty.
|
|
*/
|
|
prev = TAILQ_LAST(&frag->fr_queue, pf_fragq);
|
|
KASSERT(prev != NULL, ("prev != NULL"));
|
|
if (prev->fe_off <= frent->fe_off)
|
|
return prev;
|
|
/*
|
|
* We want to find a fragment entry that is before frag, but still
|
|
* close to it. Find the first fragment entry that is in the same
|
|
* entry point or in the first entry point after that. As we have
|
|
* already checked that there are entries behind frag, this will
|
|
* succeed.
|
|
*/
|
|
for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS;
|
|
index++) {
|
|
prev = frag->fr_firstoff[index];
|
|
if (prev != NULL)
|
|
break;
|
|
}
|
|
KASSERT(prev != NULL, ("prev != NULL"));
|
|
/*
|
|
* In prev we may have a fragment from the same entry point that is
|
|
* before frent, or one that is just one position behind frent.
|
|
* In the latter case, we go back one step and have the predecessor.
|
|
* There may be none if the new fragment will be the first one.
|
|
*/
|
|
if (prev->fe_off > frent->fe_off) {
|
|
prev = TAILQ_PREV(prev, pf_fragq, fr_next);
|
|
if (prev == NULL)
|
|
return NULL;
|
|
KASSERT(prev->fe_off <= frent->fe_off,
|
|
("prev->fe_off <= frent->fe_off"));
|
|
return prev;
|
|
}
|
|
/*
|
|
* In prev is the first fragment of the entry point. The offset
|
|
* of frag is behind it. Find the closest previous fragment.
|
|
*/
|
|
for (next = TAILQ_NEXT(prev, fr_next); next != NULL;
|
|
next = TAILQ_NEXT(next, fr_next)) {
|
|
if (next->fe_off > frent->fe_off)
|
|
break;
|
|
prev = next;
|
|
}
|
|
return prev;
|
|
}
|
|
|
|
static struct pf_fragment *
|
|
pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
|
|
u_short *reason)
|
|
{
|
|
struct pf_frent *after, *next, *prev;
|
|
struct pf_fragment *frag;
|
|
uint16_t total;
|
|
|
|
PF_FRAG_ASSERT();
|
|
|
|
/* No empty fragments. */
|
|
if (frent->fe_len == 0) {
|
|
DPFPRINTF(("bad fragment: len 0"));
|
|
goto bad_fragment;
|
|
}
|
|
|
|
/* All fragments are 8 byte aligned. */
|
|
if (frent->fe_mff && (frent->fe_len & 0x7)) {
|
|
DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
|
|
goto bad_fragment;
|
|
}
|
|
|
|
/* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
|
|
if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
|
|
DPFPRINTF(("bad fragment: max packet %d",
|
|
frent->fe_off + frent->fe_len));
|
|
goto bad_fragment;
|
|
}
|
|
|
|
DPFPRINTF((key->frc_af == AF_INET ?
|
|
"reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
|
|
key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
|
|
|
|
/* Fully buffer all of the fragments in this fragment queue. */
|
|
frag = pf_find_fragment(key, &V_pf_frag_tree);
|
|
|
|
/* 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) {
|
|
REASON_SET(reason, PFRES_MEMORY);
|
|
goto drop_fragment;
|
|
}
|
|
}
|
|
|
|
*(struct pf_fragment_cmp *)frag = *key;
|
|
memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff));
|
|
memset(frag->fr_entries, 0, sizeof(frag->fr_entries));
|
|
frag->fr_timeout = time_uptime;
|
|
frag->fr_maxlen = frent->fe_len;
|
|
frag->fr_holes = 1;
|
|
TAILQ_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, cannot fail. */
|
|
pf_frent_insert(frag, frent, NULL);
|
|
|
|
return (frag);
|
|
}
|
|
|
|
KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
|
|
|
|
/* Remember maximum fragment len for refragmentation. */
|
|
if (frent->fe_len > frag->fr_maxlen)
|
|
frag->fr_maxlen = frent->fe_len;
|
|
|
|
/* Maximum data we have seen already. */
|
|
total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
|
|
TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
|
|
|
|
/* Non terminal fragments must have more fragments flag. */
|
|
if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
|
|
goto bad_fragment;
|
|
|
|
/* Check if we saw the last fragment already. */
|
|
if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
|
|
if (frent->fe_off + frent->fe_len > total ||
|
|
(frent->fe_off + frent->fe_len == total && frent->fe_mff))
|
|
goto bad_fragment;
|
|
} else {
|
|
if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
|
|
goto bad_fragment;
|
|
}
|
|
|
|
/* Find neighbors for newly inserted fragment */
|
|
prev = pf_frent_previous(frag, frent);
|
|
if (prev == NULL) {
|
|
after = TAILQ_FIRST(&frag->fr_queue);
|
|
KASSERT(after != NULL, ("after != NULL"));
|
|
} else {
|
|
after = TAILQ_NEXT(prev, fr_next);
|
|
}
|
|
|
|
if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
|
|
uint16_t precut;
|
|
|
|
precut = prev->fe_off + prev->fe_len - frent->fe_off;
|
|
if (precut >= frent->fe_len)
|
|
goto bad_fragment;
|
|
DPFPRINTF(("overlap -%d", precut));
|
|
m_adj(frent->fe_m, precut);
|
|
frent->fe_off += precut;
|
|
frent->fe_len -= precut;
|
|
}
|
|
|
|
for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
|
|
after = next) {
|
|
uint16_t aftercut;
|
|
|
|
aftercut = frent->fe_off + frent->fe_len - after->fe_off;
|
|
DPFPRINTF(("adjust overlap %d", aftercut));
|
|
if (aftercut < after->fe_len) {
|
|
m_adj(after->fe_m, aftercut);
|
|
after->fe_off += aftercut;
|
|
after->fe_len -= aftercut;
|
|
break;
|
|
}
|
|
|
|
/* This fragment is completely overlapped, lose it. */
|
|
next = TAILQ_NEXT(after, fr_next);
|
|
pf_frent_remove(frag, after);
|
|
m_freem(after->fe_m);
|
|
uma_zfree(V_pf_frent_z, after);
|
|
}
|
|
|
|
/* If part of the queue gets too long, there is not way to recover. */
|
|
if (pf_frent_insert(frag, frent, prev)) {
|
|
DPFPRINTF(("fragment queue limit exceeded"));
|
|
goto bad_fragment;
|
|
}
|
|
|
|
return (frag);
|
|
|
|
bad_fragment:
|
|
REASON_SET(reason, PFRES_FRAG);
|
|
drop_fragment:
|
|
uma_zfree(V_pf_frent_z, frent);
|
|
return (NULL);
|
|
}
|
|
|
|
static struct mbuf *
|
|
pf_join_fragment(struct pf_fragment *frag)
|
|
{
|
|
struct mbuf *m, *m2;
|
|
struct pf_frent *frent, *next;
|
|
|
|
frent = TAILQ_FIRST(&frag->fr_queue);
|
|
next = TAILQ_NEXT(frent, fr_next);
|
|
|
|
m = frent->fe_m;
|
|
m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
|
|
uma_zfree(V_pf_frent_z, frent);
|
|
for (frent = next; frent != NULL; frent = next) {
|
|
next = TAILQ_NEXT(frent, fr_next);
|
|
|
|
m2 = frent->fe_m;
|
|
/* Strip off ip header. */
|
|
m_adj(m2, frent->fe_hdrlen);
|
|
/* Strip off any trailing bytes. */
|
|
m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
|
|
|
|
uma_zfree(V_pf_frent_z, frent);
|
|
m_cat(m, m2);
|
|
}
|
|
|
|
/* Remove from fragment queue. */
|
|
pf_remove_fragment(frag);
|
|
|
|
return (m);
|
|
}
|
|
|
|
#ifdef INET
|
|
static int
|
|
pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
|
|
{
|
|
struct mbuf *m = *m0;
|
|
struct pf_frent *frent;
|
|
struct pf_fragment *frag;
|
|
struct pf_fragment_cmp key;
|
|
uint16_t total, hdrlen;
|
|
|
|
/* Get an entry for the fragment queue */
|
|
if ((frent = pf_create_fragment(reason)) == NULL)
|
|
return (PF_DROP);
|
|
|
|
frent->fe_m = m;
|
|
frent->fe_hdrlen = ip->ip_hl << 2;
|
|
frent->fe_extoff = 0;
|
|
frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
|
|
frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
|
|
frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
|
|
|
|
pf_ip2key(ip, dir, &key);
|
|
|
|
if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
|
|
return (PF_DROP);
|
|
|
|
/* The mbuf is part of the fragment entry, no direct free or access */
|
|
m = *m0 = NULL;
|
|
|
|
if (frag->fr_holes) {
|
|
DPFPRINTF(("frag %d, holes %d", frag->fr_id, frag->fr_holes));
|
|
return (PF_PASS); /* drop because *m0 is NULL, no error */
|
|
}
|
|
|
|
/* We have all the data */
|
|
frent = TAILQ_FIRST(&frag->fr_queue);
|
|
KASSERT(frent != NULL, ("frent != NULL"));
|
|
total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
|
|
TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
|
|
hdrlen = frent->fe_hdrlen;
|
|
|
|
m = *m0 = pf_join_fragment(frag);
|
|
frag = NULL;
|
|
|
|
if (m->m_flags & M_PKTHDR) {
|
|
int plen = 0;
|
|
for (m = *m0; m; m = m->m_next)
|
|
plen += m->m_len;
|
|
m = *m0;
|
|
m->m_pkthdr.len = plen;
|
|
}
|
|
|
|
ip = mtod(m, struct ip *);
|
|
ip->ip_len = htons(hdrlen + total);
|
|
ip->ip_off &= ~(IP_MF|IP_OFFMASK);
|
|
|
|
if (hdrlen + total > IP_MAXPACKET) {
|
|
DPFPRINTF(("drop: too big: %d", total));
|
|
ip->ip_len = 0;
|
|
REASON_SET(reason, PFRES_SHORT);
|
|
/* PF_DROP requires a valid mbuf *m0 in pf_test() */
|
|
return (PF_DROP);
|
|
}
|
|
|
|
DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
|
|
return (PF_PASS);
|
|
}
|
|
#endif /* INET */
|
|
|
|
#ifdef INET6
|
|
static int
|
|
pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
|
|
uint16_t hdrlen, uint16_t extoff, u_short *reason)
|
|
{
|
|
struct mbuf *m = *m0;
|
|
struct pf_frent *frent;
|
|
struct pf_fragment *frag;
|
|
struct pf_fragment_cmp key;
|
|
struct m_tag *mtag;
|
|
struct pf_fragment_tag *ftag;
|
|
int off;
|
|
uint32_t frag_id;
|
|
uint16_t total, maxlen;
|
|
uint8_t proto;
|
|
|
|
PF_FRAG_LOCK();
|
|
|
|
/* Get an entry for the fragment queue. */
|
|
if ((frent = pf_create_fragment(reason)) == NULL) {
|
|
PF_FRAG_UNLOCK();
|
|
return (PF_DROP);
|
|
}
|
|
|
|
frent->fe_m = m;
|
|
frent->fe_hdrlen = hdrlen;
|
|
frent->fe_extoff = extoff;
|
|
frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
|
|
frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
|
|
frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
|
|
|
|
key.frc_src.v6 = ip6->ip6_src;
|
|
key.frc_dst.v6 = ip6->ip6_dst;
|
|
key.frc_af = AF_INET6;
|
|
/* Only the first fragment's protocol is relevant. */
|
|
key.frc_proto = 0;
|
|
key.frc_id = fraghdr->ip6f_ident;
|
|
|
|
if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
|
|
PF_FRAG_UNLOCK();
|
|
return (PF_DROP);
|
|
}
|
|
|
|
/* The mbuf is part of the fragment entry, no direct free or access. */
|
|
m = *m0 = NULL;
|
|
|
|
if (frag->fr_holes) {
|
|
DPFPRINTF(("frag %d, holes %d", frag->fr_id, frag->fr_holes));
|
|
PF_FRAG_UNLOCK();
|
|
return (PF_PASS); /* Drop because *m0 is NULL, no error. */
|
|
}
|
|
|
|
/* We have all the data. */
|
|
frent = TAILQ_FIRST(&frag->fr_queue);
|
|
KASSERT(frent != NULL, ("frent != NULL"));
|
|
extoff = frent->fe_extoff;
|
|
maxlen = frag->fr_maxlen;
|
|
frag_id = frag->fr_id;
|
|
total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
|
|
TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
|
|
hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
|
|
|
|
m = *m0 = pf_join_fragment(frag);
|
|
frag = NULL;
|
|
|
|
PF_FRAG_UNLOCK();
|
|
|
|
/* Take protocol from first fragment header. */
|
|
m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
|
|
KASSERT(m, ("%s: short mbuf chain", __func__));
|
|
proto = *(mtod(m, caddr_t) + off);
|
|
m = *m0;
|
|
|
|
/* Delete frag6 header */
|
|
if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
|
|
goto fail;
|
|
|
|
if (m->m_flags & M_PKTHDR) {
|
|
int plen = 0;
|
|
for (m = *m0; m; m = m->m_next)
|
|
plen += m->m_len;
|
|
m = *m0;
|
|
m->m_pkthdr.len = plen;
|
|
}
|
|
|
|
if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
|
|
M_NOWAIT)) == NULL)
|
|
goto fail;
|
|
ftag = (struct pf_fragment_tag *)(mtag + 1);
|
|
ftag->ft_hdrlen = hdrlen;
|
|
ftag->ft_extoff = extoff;
|
|
ftag->ft_maxlen = maxlen;
|
|
ftag->ft_id = frag_id;
|
|
m_tag_prepend(m, mtag);
|
|
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
|
|
if (extoff) {
|
|
/* Write protocol into next field of last extension header. */
|
|
m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
|
|
&off);
|
|
KASSERT(m, ("%s: short mbuf chain", __func__));
|
|
*(mtod(m, char *) + off) = proto;
|
|
m = *m0;
|
|
} else
|
|
ip6->ip6_nxt = proto;
|
|
|
|
if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
|
|
DPFPRINTF(("drop: too big: %d", total));
|
|
ip6->ip6_plen = 0;
|
|
REASON_SET(reason, PFRES_SHORT);
|
|
/* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
|
|
return (PF_DROP);
|
|
}
|
|
|
|
DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
|
|
return (PF_PASS);
|
|
|
|
fail:
|
|
REASON_SET(reason, PFRES_MEMORY);
|
|
/* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
|
|
return (PF_DROP);
|
|
}
|
|
#endif /* INET6 */
|
|
|
|
#ifdef INET6
|
|
int
|
|
pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
|
|
{
|
|
struct mbuf *m = *m0, *t;
|
|
struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1);
|
|
struct pf_pdesc pd;
|
|
uint32_t frag_id;
|
|
uint16_t hdrlen, extoff, maxlen;
|
|
uint8_t proto;
|
|
int error, action;
|
|
|
|
hdrlen = ftag->ft_hdrlen;
|
|
extoff = ftag->ft_extoff;
|
|
maxlen = ftag->ft_maxlen;
|
|
frag_id = ftag->ft_id;
|
|
m_tag_delete(m, mtag);
|
|
mtag = NULL;
|
|
ftag = NULL;
|
|
|
|
if (extoff) {
|
|
int off;
|
|
|
|
/* Use protocol from next field of last extension header */
|
|
m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
|
|
&off);
|
|
KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
|
|
proto = *(mtod(m, caddr_t) + off);
|
|
*(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
|
|
m = *m0;
|
|
} else {
|
|
struct ip6_hdr *hdr;
|
|
|
|
hdr = mtod(m, struct ip6_hdr *);
|
|
proto = hdr->ip6_nxt;
|
|
hdr->ip6_nxt = IPPROTO_FRAGMENT;
|
|
}
|
|
|
|
/* The MTU must be a multiple of 8 bytes, or we risk doing the
|
|
* fragmentation wrong. */
|
|
maxlen = maxlen & ~7;
|
|
|
|
/*
|
|
* Maxlen may be less than 8 if there was only a single
|
|
* fragment. As it was fragmented before, add a fragment
|
|
* header also for a single fragment. If total or maxlen
|
|
* is less than 8, ip6_fragment() will return EMSGSIZE and
|
|
* we drop the packet.
|
|
*/
|
|
error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
|
|
m = (*m0)->m_nextpkt;
|
|
(*m0)->m_nextpkt = NULL;
|
|
if (error == 0) {
|
|
/* The first mbuf contains the unfragmented packet. */
|
|
m_freem(*m0);
|
|
*m0 = NULL;
|
|
action = PF_PASS;
|
|
} else {
|
|
/* Drop expects an mbuf to free. */
|
|
DPFPRINTF(("refragment error %d", error));
|
|
action = PF_DROP;
|
|
}
|
|
for (t = m; m; m = t) {
|
|
t = m->m_nextpkt;
|
|
m->m_nextpkt = NULL;
|
|
m->m_flags |= M_SKIP_FIREWALL;
|
|
memset(&pd, 0, sizeof(pd));
|
|
pd.pf_mtag = pf_find_mtag(m);
|
|
if (error == 0)
|
|
ip6_forward(m, 0);
|
|
else
|
|
m_freem(m);
|
|
}
|
|
|
|
return (action);
|
|
}
|
|
#endif /* INET6 */
|
|
|
|
#ifdef INET
|
|
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 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;
|
|
int verdict;
|
|
|
|
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)) {
|
|
REASON_SET(reason, PFRES_NORM);
|
|
goto drop;
|
|
}
|
|
|
|
if (hlen > ntohs(h->ip_len)) {
|
|
REASON_SET(reason, PFRES_NORM);
|
|
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;
|
|
|
|
/* Fully buffer all of the fragments
|
|
* Might return a completely reassembled mbuf, or NULL */
|
|
PF_FRAG_LOCK();
|
|
DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
|
|
verdict = pf_reassemble(m0, h, dir, reason);
|
|
PF_FRAG_UNLOCK();
|
|
|
|
if (verdict != PF_PASS)
|
|
return (PF_DROP);
|
|
|
|
m = *m0;
|
|
if (m == NULL)
|
|
return (PF_DROP);
|
|
|
|
h = mtod(m, struct ip *);
|
|
|
|
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);
|
|
}
|
|
|
|
pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
|
|
|
|
return (PF_PASS);
|
|
|
|
bad:
|
|
DPFPRINTF(("dropping bad fragment\n"));
|
|
REASON_SET(reason, PFRES_FRAG);
|
|
drop:
|
|
if (r != NULL && r->log)
|
|
PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
|
|
1);
|
|
|
|
return (PF_DROP);
|
|
}
|
|
#endif
|
|
|
|
#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 extoff;
|
|
int off;
|
|
struct ip6_ext ext;
|
|
struct ip6_opt opt;
|
|
struct ip6_frag frag;
|
|
u_int32_t plen;
|
|
int optend;
|
|
int ooff;
|
|
u_int8_t proto;
|
|
int terminal;
|
|
|
|
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_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, kif, M_GETFIB(m)))
|
|
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, NULL, M_GETFIB(m)))
|
|
r = r->skip[PF_SKIP_DST_ADDR].ptr;
|
|
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 (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
|
|
goto drop;
|
|
|
|
plen = ntohs(h->ip6_plen);
|
|
/* jumbo payload option not supported */
|
|
if (plen == 0)
|
|
goto drop;
|
|
|
|
extoff = 0;
|
|
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;
|
|
extoff = off;
|
|
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;
|
|
extoff = off;
|
|
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;
|
|
if (opt.ip6o_type == IP6OPT_JUMBO)
|
|
goto drop;
|
|
ooff += sizeof(opt) + opt.ip6o_len;
|
|
} while (ooff < optend);
|
|
|
|
off = optend;
|
|
proto = ext.ip6e_nxt;
|
|
break;
|
|
default:
|
|
terminal = 1;
|
|
break;
|
|
}
|
|
} while (!terminal);
|
|
|
|
if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
|
|
goto shortpkt;
|
|
|
|
pf_scrub_ip6(&m, r->min_ttl);
|
|
|
|
return (PF_PASS);
|
|
|
|
fragment:
|
|
if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
|
|
goto shortpkt;
|
|
|
|
if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
|
|
goto shortpkt;
|
|
|
|
/* Offset now points to data portion. */
|
|
off += sizeof(frag);
|
|
|
|
/* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
|
|
if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
|
|
return (PF_DROP);
|
|
m = *m0;
|
|
if (m == NULL)
|
|
return (PF_DROP);
|
|
|
|
pd->flags |= PFDESC_IP_REAS;
|
|
return (PF_PASS);
|
|
|
|
shortpkt:
|
|
REASON_SET(reason, PFRES_SHORT);
|
|
if (r != NULL && r->log)
|
|
PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
|
|
1);
|
|
return (PF_DROP);
|
|
|
|
drop:
|
|
REASON_SET(reason, PFRES_NORM);
|
|
if (r != NULL && r->log)
|
|
PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
|
|
1);
|
|
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;
|
|
|
|
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)
|
|
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, kif, M_GETFIB(m)))
|
|
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, NULL, M_GETFIB(m)))
|
|
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[dir == PF_OUT]++;
|
|
r->bytes[dir == PF_OUT] += pd->tot_len;
|
|
}
|
|
|
|
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)
|
|
goto tcp_drop;
|
|
} 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_proto_cksum_fixup(m, 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_proto_cksum_fixup(m, 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, pd->af))
|
|
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, m, AF_INET, dir, reason, r, NULL, NULL, pd,
|
|
1);
|
|
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;
|
|
|
|
KASSERT((src->scrub == NULL),
|
|
("pf_normalize_tcp_init: src->scrub != NULL"));
|
|
|
|
src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
|
|
if (src->scrub == NULL)
|
|
return (1);
|
|
|
|
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)
|
|
uma_zfree(V_pf_state_scrub_z, state->src.scrub);
|
|
if (state->dst.scrub)
|
|
uma_zfree(V_pf_state_scrub_z, 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;
|
|
|
|
KASSERT((src->scrub || dst->scrub),
|
|
("%s: src->scrub && dst->scrub!", __func__));
|
|
|
|
/*
|
|
* 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 (V_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_proto_a(m, &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_proto_a(m, &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_uptime - state->creation > TS_MAX_CONN)) {
|
|
if (V_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 (V_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 original
|
|
* 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 = V_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 */
|
|
delta_ts = uptime;
|
|
timevalsub(&delta_ts, &src->scrub->pfss_last);
|
|
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' : ' '));
|
|
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));
|
|
if (V_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 (V_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 immediately 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 (V_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);
|
|
}
|
|
|
|
static int
|
|
pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
|
|
int off, sa_family_t af)
|
|
{
|
|
u_int16_t *mss;
|
|
int thoff;
|
|
int opt, cnt, optlen = 0;
|
|
int rewrite = 0;
|
|
u_char opts[TCP_MAXOLEN];
|
|
u_char *optp = opts;
|
|
|
|
thoff = th->th_off << 2;
|
|
cnt = thoff - sizeof(struct tcphdr);
|
|
|
|
if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
|
|
NULL, NULL, af))
|
|
return (rewrite);
|
|
|
|
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_proto_cksum_fixup(m,
|
|
th->th_sum, *mss, htons(r->max_mss), 0);
|
|
*mss = htons(r->max_mss);
|
|
rewrite = 1;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (rewrite)
|
|
m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
|
|
|
|
return (rewrite);
|
|
}
|
|
|
|
#ifdef INET
|
|
static void
|
|
pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
|
|
{
|
|
struct mbuf *m = *m0;
|
|
struct ip *h = mtod(m, struct ip *);
|
|
|
|
/* Clear IP_DF if no-df was requested */
|
|
if (flags & 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);
|
|
}
|
|
|
|
/* Enforce a minimum ttl, may cause endless packet loops */
|
|
if (min_ttl && h->ip_ttl < min_ttl) {
|
|
u_int16_t ip_ttl = h->ip_ttl;
|
|
|
|
h->ip_ttl = min_ttl;
|
|
h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
|
|
}
|
|
|
|
/* Enforce tos */
|
|
if (flags & PFRULE_SET_TOS) {
|
|
u_int16_t ov, nv;
|
|
|
|
ov = *(u_int16_t *)h;
|
|
h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
|
|
nv = *(u_int16_t *)h;
|
|
|
|
h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
|
|
}
|
|
|
|
/* random-id, but not for fragments */
|
|
if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
|
|
uint16_t ip_id = h->ip_id;
|
|
|
|
ip_fillid(h);
|
|
h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
|
|
}
|
|
}
|
|
#endif /* INET */
|
|
|
|
#ifdef INET6
|
|
static void
|
|
pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
|
|
{
|
|
struct mbuf *m = *m0;
|
|
struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
|
|
|
|
/* Enforce a minimum ttl, may cause endless packet loops */
|
|
if (min_ttl && h->ip6_hlim < min_ttl)
|
|
h->ip6_hlim = min_ttl;
|
|
}
|
|
#endif
|