ah_output.c   [plain text]

/*
 * Copyright (c) 2008-2019 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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 */

/*	$FreeBSD: src/sys/netinet6/ah_output.c,v 1.1.2.3 2001/07/03 11:01:49 ume Exp $	*/
/*	$KAME: ah_output.c,v 1.30 2001/02/21 00:50:53 itojun Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * RFC1826/2402 authentication header.
 */

#define _IP_VHL

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/route.h>

#include <netinet/in.h>

#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_var.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>

#include <netinet6/ipsec.h>
#include <netinet6/ipsec6.h>
#include <netinet6/ah.h>
#include <netinet6/ah6.h>
#include <netkey/key.h>
#include <netkey/keydb.h>

#include <net/net_osdep.h>

#if INET
static struct in_addr *ah4_finaldst(struct mbuf *);
#endif

extern lck_mtx_t *sadb_mutex;

/*
 * compute AH header size.
 * transport mode only.  for tunnel mode, we should implement
 * virtual interface, and control MTU/MSS by the interface MTU.
 */
size_t
ah_hdrsiz(struct ipsecrequest *isr)
{
	/* sanity check */
	if (isr == NULL) {
		panic("ah_hdrsiz: NULL was passed.\n");
	}

	if (isr->saidx.proto != IPPROTO_AH) {
		panic("unsupported mode passed to ah_hdrsiz");
	}

#if 0
	{
		lck_mtx_lock(sadb_mutex);
		const struct ah_algorithm *algo;
		size_t hdrsiz;

		/*%%%%% this needs to change - no sav in ipsecrequest any more */
		if (isr->sav == NULL) {
			goto estimate;
		}
		if (isr->sav->state != SADB_SASTATE_MATURE
		    && isr->sav->state != SADB_SASTATE_DYING) {
			goto estimate;
		}

		/* we need transport mode AH. */
		algo = ah_algorithm_lookup(isr->sav->alg_auth);
		if (!algo) {
			goto estimate;
		}

		/*
		 * XXX
		 * right now we don't calcurate the padding size.  simply
		 * treat the padding size as constant, for simplicity.
		 *
		 * XXX variable size padding support
		 */
		hdrsiz = (((*algo->sumsiz)(isr->sav) + 3) & ~(4 - 1));
		if (isr->sav->flags & SADB_X_EXT_OLD) {
			hdrsiz += sizeof(struct ah);
		} else {
			hdrsiz += sizeof(struct newah);
		}

		lck_mtx_unlock(sadb_mutex);
		return hdrsiz;
	}

estimate:
#endif

	//lck_mtx_unlock(sadb_mutex);
	/* ASSUMING:
	 *	sizeof(struct newah) > sizeof(struct ah).
	 *	16 = (16 + 3) & ~(4 - 1).
	 */
	return sizeof(struct newah) + 16;
}

#if INET
/*
 * Modify the packet so that it includes the authentication data.
 * The mbuf passed must start with IPv4 header.
 *
 * assumes that the first mbuf contains IPv4 header + option only.
 * the function does not modify m.
 */
int
ah4_output(struct mbuf *m, struct secasvar *sav)
{
	const struct ah_algorithm *algo;
	u_int32_t spi;
	u_char *ahdrpos;
	u_char *ahsumpos = NULL;
	size_t hlen = 0;        /*IP header+option in bytes*/
	size_t plen = 0;        /*AH payload size in bytes*/
	size_t ahlen = 0;       /*plen + sizeof(ah)*/
	struct ip *ip;
	struct in_addr dst = { .s_addr = 0 };
	struct in_addr *finaldst;
	int error;

	/* sanity checks */
	if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay[0] == NULL) {
		ip = mtod(m, struct ip *);
		ipseclog((LOG_DEBUG, "ah4_output: internal error: "
		    "sav->replay is null: %x->%x, SPI=%u\n",
		    (u_int32_t)ntohl(ip->ip_src.s_addr),
		    (u_int32_t)ntohl(ip->ip_dst.s_addr),
		    (u_int32_t)ntohl(sav->spi)));
		IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
		m_freem(m);
		return EINVAL;
	}

	algo = ah_algorithm_lookup(sav->alg_auth);
	if (!algo) {
		ipseclog((LOG_ERR, "ah4_output: unsupported algorithm: "
		    "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
		IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
		m_freem(m);
		return EINVAL;
	}
	spi = sav->spi;

	/*
	 * determine the size to grow.
	 */
	if (sav->flags & SADB_X_EXT_OLD) {
		/* RFC 1826 */
		plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
		ahlen = plen + sizeof(struct ah);
	} else {
		/* RFC 2402 */
		plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
		ahlen = plen + sizeof(struct newah);
	}

	VERIFY(ahlen <= UINT16_MAX);

	/*
	 * grow the mbuf to accomodate AH.
	 */
	ip = mtod(m, struct ip *);
#ifdef _IP_VHL
	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
#else
	hlen = ip->ip_hl << 2;
#endif

	if (m->m_len != hlen) {
		panic("ah4_output: assumption failed (first mbuf length)");
	}
	if (M_LEADINGSPACE(m->m_next) < ahlen) {
		struct mbuf *n;
		MGET(n, M_DONTWAIT, MT_DATA);
		if (!n) {
			ipseclog((LOG_DEBUG, "ENOBUFS in ah4_output %d\n",
			    __LINE__));
			m_freem(m);
			return ENOBUFS;
		}
		n->m_len = (int32_t)ahlen;
		n->m_next = m->m_next;
		m->m_next = n;
		m->m_pkthdr.len += ahlen;
		ahdrpos = mtod(n, u_char *);
	} else {
		m->m_next->m_len += ahlen;
		m->m_next->m_data -= ahlen;
		m->m_pkthdr.len += ahlen;
		ahdrpos = mtod(m->m_next, u_char *);
	}

	ip = mtod(m, struct ip *);      /*just to be sure*/

	/*
	 * initialize AH.
	 */
	if (sav->flags & SADB_X_EXT_OLD) {
		struct ah *ahdr;

		VERIFY((plen >> 2) <= UINT8_MAX);
		ahdr = (struct ah *)(void *)ahdrpos;
		ahsumpos = (u_char *)(ahdr + 1);
		ahdr->ah_len = (u_int8_t)(plen >> 2);
		ahdr->ah_nxt = ip->ip_p;
		ahdr->ah_reserve = htons(0);
		ahdr->ah_spi = spi;
		bzero(ahdr + 1, plen);
	} else {
		struct newah *ahdr;

		VERIFY(((plen >> 2) + 1) <= UINT8_MAX);
		ahdr = (struct newah *)(void *)ahdrpos;
		ahsumpos = (u_char *)(ahdr + 1);
		ahdr->ah_len = (u_int8_t)((plen >> 2) + 1); /* plus one for seq# */
		ahdr->ah_nxt = ip->ip_p;
		ahdr->ah_reserve = htons(0);
		ahdr->ah_spi = spi;
		if (sav->replay[0]->count == ~0) {
			if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
				/* XXX Is it noisy ? */
				ipseclog((LOG_WARNING,
				    "replay counter overflowed. %s\n",
				    ipsec_logsastr(sav)));
				IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
				m_freem(m);
				return EINVAL;
			}
		}
		lck_mtx_lock(sadb_mutex);
		sav->replay[0]->count++;
		lck_mtx_unlock(sadb_mutex);
		/*
		 * XXX sequence number must not be cycled, if the SA is
		 * installed by IKE daemon.
		 */
		ahdr->ah_seq = htonl(sav->replay[0]->count);
		bzero(ahdr + 1, plen);
	}

	/*
	 * modify IPv4 header.
	 */
	ip->ip_p = IPPROTO_AH;
	if (ahlen < (IP_MAXPACKET - ntohs(ip->ip_len))) {
		ip->ip_len = htons(ntohs(ip->ip_len) + (u_int16_t)ahlen);
	} else {
		ipseclog((LOG_ERR, "IPv4 AH output: size exceeds limit\n"));
		IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
		m_freem(m);
		return EMSGSIZE;
	}

	/*
	 * If there is source routing option, update destination field in
	 * the IPv4 header to the final destination.
	 * Note that we do not need to update source routing option itself
	 * (as done in IPv4 AH processing -- see ip6_output()), since
	 * source routing option is not part of the ICV computation.
	 */
	finaldst = ah4_finaldst(m);
	if (finaldst) {
		dst.s_addr = ip->ip_dst.s_addr;
		ip->ip_dst.s_addr = finaldst->s_addr;
	}

	/*
	 * calcurate the checksum, based on security association
	 * and the algorithm specified.
	 */
	error = ah4_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
	if (error) {
		ipseclog((LOG_ERR,
		    "error after ah4_calccksum, called from ah4_output"));
		m_freem(m);
		m = NULL;
		IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
		return error;
	}

	if (finaldst) {
		ip = mtod(m, struct ip *);      /*just to make sure*/
		ip->ip_dst.s_addr = dst.s_addr;
	}
	lck_mtx_lock(sadb_stat_mutex);
	ipsecstat.out_success++;
	ipsecstat.out_ahhist[sav->alg_auth]++;
	lck_mtx_unlock(sadb_stat_mutex);
	key_sa_recordxfer(sav, m);

	return 0;
}
#endif

/* Calculate AH length */
size_t
ah_hdrlen(struct secasvar *sav)
{
	const struct ah_algorithm *algo;
	size_t plen, ahlen;

	algo = ah_algorithm_lookup(sav->alg_auth);
	if (!algo) {
		return 0;
	}
	if (sav->flags & SADB_X_EXT_OLD) {
		/* RFC 1826 */
		plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
		ahlen = plen + sizeof(struct ah);
	} else {
		/* RFC 2402 */
		plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
		ahlen = plen + sizeof(struct newah);
	}

	return ahlen;
}

/*
 * Fill in the Authentication Header and calculate checksum.
 */
int
ah6_output(struct mbuf *m, u_char *nexthdrp, struct mbuf *md,
    struct secasvar *sav)
{
	struct mbuf *mprev;
	struct mbuf *mah;
	const struct ah_algorithm *algo;
	u_int32_t spi;
	u_char *ahsumpos = NULL;
	size_t plen;    /*AH payload size in bytes*/
	int error = 0;
	size_t ahlen;
	struct ip6_hdr *ip6;

	if (m->m_len < sizeof(struct ip6_hdr)) {
		ipseclog((LOG_DEBUG, "ah6_output: first mbuf too short\n"));
		m_freem(m);
		return EINVAL;
	}

	ahlen = ah_hdrlen(sav);
	if (ahlen == 0) {
		return 0;
	}

	VERIFY(ahlen <= UINT16_MAX);

	for (mprev = m; mprev && mprev->m_next != md; mprev = mprev->m_next) {
		;
	}
	if (!mprev || mprev->m_next != md) {
		ipseclog((LOG_DEBUG, "ah6_output: md is not in chain\n"));
		m_freem(m);
		return EINVAL;
	}

	MGET(mah, M_DONTWAIT, MT_DATA);
	if (!mah) {
		m_freem(m);
		return ENOBUFS;
	}
	if (ahlen > MLEN) {
		MCLGET(mah, M_DONTWAIT);
		if ((mah->m_flags & M_EXT) == 0) {
			m_free(mah);
			m_freem(m);
			return ENOBUFS;
		}
	}
	mah->m_len = (int32_t)ahlen;
	mah->m_next = md;
	mprev->m_next = mah;
	m->m_pkthdr.len += ahlen;

	/* fix plen */
	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) > IPV6_MAXPACKET) {
		ipseclog((LOG_ERR,
		    "ip6_output: AH with IPv6 jumbogram is not supported\n"));
		m_freem(m);
		return EINVAL;
	}

	ip6 = mtod(m, struct ip6_hdr *);
	ip6->ip6_plen = htons((u_int16_t)(m->m_pkthdr.len - sizeof(struct ip6_hdr)));

	if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay[0] == NULL) {
		ipseclog((LOG_DEBUG, "ah6_output: internal error: "
		    "sav->replay is null: SPI=%u\n",
		    (u_int32_t)ntohl(sav->spi)));
		IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
		m_freem(m);
		return EINVAL;
	}

	algo = ah_algorithm_lookup(sav->alg_auth);
	if (!algo) {
		ipseclog((LOG_ERR, "ah6_output: unsupported algorithm: "
		    "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
		IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
		m_freem(m);
		return EINVAL;
	}
	spi = sav->spi;

	/*
	 * initialize AH.
	 */
	if (sav->flags & SADB_X_EXT_OLD) {
		struct ah *ahdr = mtod(mah, struct ah *);

		plen = mah->m_len - sizeof(struct ah);
		VERIFY((plen >> 2) <= UINT8_MAX);
		ahsumpos = (u_char *)(ahdr + 1);
		ahdr->ah_nxt = *nexthdrp;
		*nexthdrp = IPPROTO_AH;
		ahdr->ah_len = (u_int8_t)(plen >> 2);
		ahdr->ah_reserve = htons(0);
		ahdr->ah_spi = spi;
		bzero(ahdr + 1, plen);
	} else {
		struct newah *ahdr = mtod(mah, struct newah *);

		plen = mah->m_len - sizeof(struct newah);
		VERIFY(((plen >> 2) + 1) <= UINT8_MAX);
		ahsumpos = (u_char *)(ahdr + 1);
		ahdr->ah_nxt = *nexthdrp;
		*nexthdrp = IPPROTO_AH;
		ahdr->ah_len = (u_int8_t)((plen >> 2) + 1); /* plus one for seq# */
		ahdr->ah_reserve = htons(0);
		ahdr->ah_spi = spi;
		if (sav->replay[0]->count == ~0) {
			if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
				/* XXX Is it noisy ? */
				ipseclog((LOG_WARNING,
				    "replay counter overflowed. %s\n",
				    ipsec_logsastr(sav)));
				IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
				m_freem(m);
				return EINVAL;
			}
		}
		lck_mtx_lock(sadb_mutex);
		sav->replay[0]->count++;
		lck_mtx_unlock(sadb_mutex);
		/*
		 * XXX sequence number must not be cycled, if the SA is
		 * installed by IKE daemon.
		 */
		ahdr->ah_seq = htonl(sav->replay[0]->count);
		bzero(ahdr + 1, plen);
	}

	/*
	 * calcurate the checksum, based on security association
	 * and the algorithm specified.
	 */
	error = ah6_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
	if (error) {
		IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
		m_freem(m);
	} else {
		IPSEC_STAT_INCREMENT(ipsec6stat.out_success);
		key_sa_recordxfer(sav, m);
	}
	IPSEC_STAT_INCREMENT(ipsec6stat.out_ahhist[sav->alg_auth]);

	return error;
}

/*
 * Find the final destination if there is loose/strict source routing option.
 * Returns NULL if there's no source routing options.
 * Returns NULL on errors too.
 * Note that this function will return a pointer INTO the given parameter,
 * struct mbuf *m.
 * The mbuf must be pulled up toward, at least, ip option part.
 */
static struct in_addr *
ah4_finaldst(struct mbuf *m)
{
	struct ip *ip;
	int optlen;
	u_char *q;
	int i;
	int hlen;

	if (!m) {
		panic("ah4_finaldst: m == NULL");
	}
	ip = mtod(m, struct ip *);
#ifdef _IP_VHL
	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
#else
	hlen = ip->ip_hl << 2;
#endif

	if (m->m_len < hlen) {
		ipseclog((LOG_DEBUG,
		    "ah4_finaldst: parameter mbuf wrong (not pulled up)\n"));
		return NULL;
	}

	if (hlen == sizeof(struct ip)) {
		return NULL;
	}

	optlen = hlen - sizeof(struct ip);
	if (optlen < 0) {
		ipseclog((LOG_DEBUG, "ah4_finaldst: wrong optlen %d\n",
		    optlen));
		return NULL;
	}

	q = (u_char *)(ip + 1);
	i = 0;
	while (i < optlen) {
		if (i + IPOPT_OPTVAL >= optlen) {
			return NULL;
		}
		if (q[i + IPOPT_OPTVAL] == IPOPT_EOL ||
		    q[i + IPOPT_OPTVAL] == IPOPT_NOP ||
		    i + IPOPT_OLEN < optlen) {
			;
		} else {
			return NULL;
		}

		switch (q[i + IPOPT_OPTVAL]) {
		case IPOPT_EOL:
			i = optlen;     /* bye */
			break;
		case IPOPT_NOP:
			i++;
			break;
		case IPOPT_LSRR:
		case IPOPT_SSRR:
			if (q[i + IPOPT_OLEN] < 2 + sizeof(struct in_addr) ||
			    optlen - i < q[i + IPOPT_OLEN]) {
				ipseclog((LOG_ERR,
				    "ip_finaldst: invalid IP option "
				    "(code=%02x len=%02x)\n",
				    q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
				return NULL;
			}
			i += q[i + IPOPT_OLEN] - sizeof(struct in_addr);
			return (struct in_addr *)(void *)(q + i);
		default:
			if (q[i + IPOPT_OLEN] < 2 ||
			    optlen - i < q[i + IPOPT_OLEN]) {
				ipseclog((LOG_ERR,
				    "ip_finaldst: invalid IP option "
				    "(code=%02x len=%02x)\n",
				    q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
				return NULL;
			}
			i += q[i + IPOPT_OLEN];
			break;
		}
	}
	return NULL;
}