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/*
* The author of this code is John Ioannidis, ji@tla.org,
* (except when noted otherwise).
*
* This code was written for BSD/OS in Athens, Greece, in November 1995.
*
* Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
* by Angelos D. Keromytis, kermit@forthnet.gr.
*
* Copyright (C) 1995, 1996, 1997 by John Ioannidis and Angelos D. Keromytis.
*
* Permission to use, copy, and modify this software without fee
* is hereby granted, provided that this entire notice is included in
* all copies of any software which is or includes a copy or
* modification of this software.
*
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTY. IN PARTICULAR, NEITHER AUTHOR MAKES ANY
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
* MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
* PURPOSE.
*/
/*
* Based on draft-ietf-ipsec-ah-hmac-sha-04.txt.
*/
#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/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/socketvar.h>
#include <machine/cpu.h>
#include <machine/endian.h>
#include <net/if.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/raw_cb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <net/encap.h>
#include <netinet/ip_ipsp.h>
#include <netinet/ip_ah.h>
/*
* ahhmacsha1_attach() is called from the transformation initialization code.
* It just returns.
*/
int
ahhmacsha1_attach()
{
return 0;
}
/*
* ahhmacsha1_init() is called when an SPI is being set up. It interprets the
* encap_msghdr present in m, and sets up the transformation data.
*/
int
ahhmacsha1_init(struct tdb *tdbp, struct xformsw *xsp, struct mbuf *m)
{
struct ahhmacsha1_xdata *xd;
struct ahhmacsha1_xencap txd;
struct encap_msghdr *em;
int len;
tdbp->tdb_xform = xsp;
MALLOC(tdbp->tdb_xdata, caddr_t, sizeof (struct ahhmacsha1_xdata),
M_XDATA, M_WAITOK);
if (tdbp->tdb_xdata == NULL)
return ENOBUFS;
bzero(tdbp->tdb_xdata, sizeof (struct ahhmacsha1_xdata));
bzero(&txd, sizeof(struct ahhmacsha1_xencap));
xd = (struct ahhmacsha1_xdata *)tdbp->tdb_xdata;
em = mtod(m, struct encap_msghdr *);
if (em->em_msglen - EMT_SETSPI_FLEN > sizeof (struct ahhmacsha1_xencap))
{
free((caddr_t)tdbp->tdb_xdata, M_XDATA);
tdbp->tdb_xdata = NULL;
return EINVAL;
}
m_copydata(m, EMT_SETSPI_FLEN, em->em_msglen - EMT_SETSPI_FLEN, (caddr_t)&txd);
xd->amx_rpl = 1;
xd->amx_alen = txd.amx_alen;
xd->amx_bitmap = 0;
xd->amx_wnd = txd.amx_wnd;
SHA1Init(&(xd->amx_ictx));
SHA1Init(&(xd->amx_octx));
for (len = 0; len < AHHMACSHA1_KMAX; len++)
txd.amx_key[len] ^= HMACSHA1_IPAD_VAL;
SHA1Update(&(xd->amx_ictx), txd.amx_key, AHHMACSHA1_KMAX);
for (len = 0; len < AHHMACSHA1_KMAX; len++)
txd.amx_key[len] ^= (HMACSHA1_IPAD_VAL ^ HMACSHA1_OPAD_VAL);
SHA1Update(&(xd->amx_octx), txd.amx_key, AHHMACSHA1_KMAX);
bzero(&txd, sizeof(struct ahhmacsha1_xencap));
bzero(ipseczeroes, IPSEC_ZEROES_SIZE); /* paranoid */
return 0;
}
/*
* Free memory
*/
int
ahhmacsha1_zeroize(struct tdb *tdbp)
{
FREE(tdbp->tdb_xdata, M_XDATA);
return 0;
}
/*
* ahhmacsha1_input() gets called to verify that an input packet
* passes authentication.
*/
extern struct ifnet loif;
struct mbuf *
ahhmacsha1_input(struct mbuf *m, struct tdb *tdb)
{
struct ahhmacsha1_xdata *xd;
struct ip *ip, ipo;
struct ah *ah;
struct ahhmacsha1 aho, *ahp;
struct ifnet *rcvif;
int ohlen, len, count, off, ado, errc;
u_int64_t btsx;
struct mbuf *m0;
SHA1_CTX ctx;
xd = (struct ahhmacsha1_xdata *)tdb->tdb_xdata;
ohlen = sizeof (struct ip) + AH_FLENGTH + xd->amx_alen;
if (xd->amx_wnd >= 0)
ohlen += HMACSHA1_RPLENGTH;
rcvif = m->m_pkthdr.rcvif;
if (rcvif == NULL)
{
#ifdef ENCDEBUG
if (encdebug)
printf("ahhmacsha1_input: receive interface is NULL!!!\n");
#endif
rcvif = &loif;
}
if (m->m_len < ohlen)
{
if ((m = m_pullup(m, ohlen)) == NULL)
{
ahstat.ahs_hdrops++;
return NULL;
}
}
ip = mtod(m, struct ip *);
ah = (struct ah *)(ip + 1);
ahp = (struct ahhmacsha1 *)ah;
if (xd->amx_wnd >= 0)
ado = HMACSHA1_RPLENGTH;
else
ado = 0;
if (ah->ah_hl != xd->amx_alen + ado)
{
#ifdef ENCDEBUG
if (encdebug)
printf("ahhmacsha1_input: bad authenticator length\n");
#endif
ahstat.ahs_badauthl++;
m_freem(m);
return NULL;
}
ipo = *ip;
ipo.ip_tos = 0;
ipo.ip_len += sizeof (struct ip); /* adjusted in ip_intr() */
HTONS(ipo.ip_len);
HTONS(ipo.ip_id);
ipo.ip_off = htons(ipo.ip_off & IP_DF); /* XXX -- and the C bit? */
ipo.ip_ttl = 0;
ipo.ip_sum = 0;
ctx = xd->amx_ictx;
SHA1Update(&ctx, (unsigned char *)&ipo, sizeof (struct ip));
if (xd->amx_wnd >= 0)
SHA1Update(&ctx, (unsigned char *)ahp,
AH_FLENGTH + HMACSHA1_RPLENGTH);
else
SHA1Update(&ctx, (unsigned char *)ahp, AH_FLENGTH);
SHA1Update(&ctx, ipseczeroes, xd->amx_alen);
/*
* Code shamelessly stolen from m_copydata
*/
off = ohlen;
len = m->m_pkthdr.len - off;
m0 = m;
while (off > 0)
{
if (m0 == 0)
panic("ahhmacsha1_input: m_copydata (off)");
if (off < m0->m_len)
break;
off -= m0->m_len;
m0 = m0->m_next;
}
while (len > 0)
{
if (m0 == 0)
panic("ahhmacsha1_input: m_copydata (copy)");
count = min(m0->m_len - off, len);
SHA1Update(&ctx, mtod(m0, unsigned char *) + off, count);
len -= count;
off = 0;
m0 = m0->m_next;
}
SHA1Final((unsigned char *)(&(aho.ah_data[0])), &ctx);
ctx = xd->amx_octx;
SHA1Update(&ctx, (unsigned char *)(&(aho.ah_data[0])),
HMACSHA1_HASHLEN);
SHA1Final((unsigned char *)(&(aho.ah_data[0])), &ctx);
if (bcmp(aho.ah_data, ah->ah_data + ado, xd->amx_alen))
{
#ifdef ENCDEBUG
if (encdebug)
printf("ahhmacsha1_input: bad auth\n"); /* XXX */
#endif
ahstat.ahs_badauth++;
m_freem(m);
return NULL;
}
if (xd->amx_wnd >= 0)
{
btsx = ntohq(ahp->ah_rpl);
if ((errc = checkreplaywindow64(btsx, &(xd->amx_rpl),
xd->amx_wnd, &(xd->amx_bitmap)))
!= 0)
{
switch(errc)
{
case 1:
#ifdef ENCDEBUG
printf("ahhmacsha1_input: replay counter wrapped\n");
#endif
ahstat.ahs_wrap++;
break;
case 2:
#ifdef ENCDEBUG
printf("ahhmacsha1_input: received old packet\n");
#endif
ahstat.ahs_replay++;
break;
case 3:
#ifdef ENCDEBUG
printf("ahhmacsha1_input: packet already received\n");
#endif
ahstat.ahs_replay++;
break;
}
m_freem(m);
return NULL;
}
}
ipo = *ip;
ipo.ip_p = ah->ah_nh;
m->m_len -= (ohlen - sizeof(struct ip));
m->m_data += (ohlen - sizeof(struct ip));
m->m_pkthdr.len -= (ohlen - sizeof(struct ip));
m->m_pkthdr.rcvif = rcvif; /* this should not be necessary */
ip = mtod(m, struct ip *);
*ip = ipo;
ip->ip_len = htons(ip->ip_len - ohlen + 2 * sizeof (struct ip));
HTONS(ip->ip_id);
HTONS(ip->ip_off);
ip->ip_sum = 0;
ip->ip_sum = in_cksum(m, sizeof (struct ip));
return m;
}
#define AHXPORT
int
ahhmacsha1_output(struct mbuf *m, struct sockaddr_encap *gw, struct tdb *tdb, struct mbuf **mp)
{
struct ahhmacsha1_xdata *xd;
struct ip *ip, ipo;
struct ah *ah;
struct ahhmacsha1 *ahp, aho;
register int len, off, count;
register struct mbuf *m0;
SHA1_CTX ctx;
int ilen, ohlen;
m = m_pullup(m, sizeof (struct ip));
if (m == NULL)
return ENOBUFS;
ip = mtod(m, struct ip *);
xd = (struct ahhmacsha1_xdata *)tdb->tdb_xdata;
ilen = ntohs(ip->ip_len);
#ifdef AHXPORT
ohlen = AH_FLENGTH + xd->amx_alen;
#else
ohlen = sizeof (struct ip) + AH_FLENGTH + xd->amx_alen;
#endif
if (xd->amx_wnd >= 0)
ohlen += HMACSHA1_RPLENGTH;
ipo.ip_v = IPVERSION;
ipo.ip_hl = 5;
ipo.ip_tos = 0;
ipo.ip_len = htons(ohlen + ilen);
ipo.ip_id = ip->ip_id;
ipo.ip_off = htons(ntohs(ip->ip_off) & IP_DF);
ipo.ip_ttl = 0;
ipo.ip_p = IPPROTO_AH;
ipo.ip_sum = 0;
#ifdef AHXPORT
ipo.ip_src = ip->ip_src;
ipo.ip_dst = ip->ip_dst;
aho.ah_nh = ip->ip_p;
#else
ipo.ip_src = gw->sen_ipsp_src;
ipo.ip_dst = gw->sen_ipsp_dst;
aho.ah_nh = IPPROTO_IP4;
#endif
aho.ah_hl = (xd->amx_alen >> 2);
if (xd->amx_wnd >= 0)
aho.ah_hl += (HMACSHA1_RPLENGTH / sizeof(u_int32_t));
aho.ah_rv = 0;
aho.ah_spi = tdb->tdb_spi;
if (xd->amx_wnd >= 0)
{
if (xd->amx_rpl == 0)
{
#ifdef ENCDEBUG
printf("ahhmacsha1_output: key should have changed long ago\n");
#endif
ahstat.ahs_wrap++;
return NULL;
}
}
aho.ah_rpl = htonq(xd->amx_rpl++);
ctx = xd->amx_ictx;
SHA1Update(&ctx, (unsigned char *)&ipo, sizeof (struct ip));
if (xd->amx_wnd >= 0)
SHA1Update(&ctx, (unsigned char *)&aho,
AH_FLENGTH + HMACSHA1_RPLENGTH);
else
SHA1Update(&ctx, (unsigned char *)&aho, AH_FLENGTH);
SHA1Update(&ctx, ipseczeroes, xd->amx_alen);
#ifdef AHXPORT
off = sizeof (struct ip);
#else
off = 0;
#endif
/*
* Code shamelessly stolen from m_copydata
*/
len = m->m_pkthdr.len - off;
m0 = m;
while (len > 0)
{
if (m0 == 0)
panic("ahhmacsha1_output: m_copydata");
count = min(m0->m_len - off, len);
SHA1Update(&ctx, mtod(m0, unsigned char *) + off, count);
len -= count;
off = 0;
m0 = m0->m_next;
}
SHA1Final((unsigned char *)(&(aho.ah_data[0])), &ctx);
ctx = xd->amx_octx;
SHA1Update(&ctx, (unsigned char *)(&(aho.ah_data[0])),
HMACSHA1_HASHLEN);
SHA1Final((unsigned char *)(&(aho.ah_data[0])), &ctx);
ipo.ip_tos = ip->ip_tos;
ipo.ip_id = ip->ip_id;
ipo.ip_off = ip->ip_off;
ipo.ip_ttl = ip->ip_ttl;
/* ipo.ip_len = ntohs(ipo.ip_len); */
M_PREPEND(m, ohlen, M_DONTWAIT);
if (m == NULL)
return ENOBUFS;
m = m_pullup(m, ohlen + sizeof (struct ip));
if (m == NULL)
return ENOBUFS;
ip = mtod(m, struct ip *);
ah = (struct ah *)(ip + 1);
ahp = (struct ahhmacsha1 *)ah;
*ip = ipo;
ah->ah_nh = aho.ah_nh;
ah->ah_hl = aho.ah_hl;
ah->ah_rv = aho.ah_rv;
ah->ah_spi = aho.ah_spi;
if (xd->amx_wnd >= 0)
{
ahp->ah_rpl = aho.ah_rpl;
bcopy((unsigned char *)(&(aho.ah_data[0])),
ahp->ah_data, xd->amx_alen);
}
else
bcopy((unsigned char *)(&(aho.ah_data[0])),
ah->ah_data, xd->amx_alen);
*mp = m;
return 0;
}
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