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      1 /*	$NetBSD: xform_tcp.c,v 1.25 2022/05/22 11:39:08 riastradh Exp $ */
      2 /*	$FreeBSD: xform_tcp.c,v 1.1.2.1 2004/02/14 22:24:09 bms Exp $ */
      3 
      4 /*
      5  * Copyright (c) 2003 Bruce M. Simpson <bms (at) spc.org>
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  *
     11  * 1. Redistributions of source code must retain the above copyright
     12  *   notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *   notice, this list of conditions and the following disclaimer in the
     15  *   documentation and/or other materials provided with the distribution.
     16  * 3. The name of the author may not be used to endorse or promote products
     17  *   derived from this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 /*
     32  * TCP MD5 Signature Option (RFC2385). Dummy code, everything is handled
     33  * in TCP directly.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 __KERNEL_RCSID(0, "$NetBSD: xform_tcp.c,v 1.25 2022/05/22 11:39:08 riastradh Exp $");
     38 
     39 #if defined(_KERNEL_OPT)
     40 #include "opt_inet.h"
     41 #endif
     42 
     43 #include <sys/param.h>
     44 #include <sys/systm.h>
     45 #include <sys/mbuf.h>
     46 #include <sys/kernel.h>
     47 
     48 #include <netinet/in.h>
     49 #include <netinet/in_systm.h>
     50 #include <netinet/ip.h>
     51 #include <netinet/ip_var.h>
     52 #ifdef TCP_SIGNATURE
     53 #include <netinet/tcp_timer.h>
     54 #include <netinet/tcp.h>
     55 #include <netinet/tcp_var.h>
     56 #endif
     57 
     58 #include <netipsec/ipsec.h>
     59 #include <netipsec/xform.h>
     60 
     61 #include <netipsec/key.h>
     62 #include <netipsec/key_debug.h>
     63 
     64 /*
     65  * Initialize a TCP-MD5 SA. Called when the SA is being set up.
     66  *
     67  * We don't need to set up the tdb prefixed fields, as we don't use the
     68  * opencrypto code; we just perform a key length check.
     69  *
     70  * XXX: Currently we only allow a single 'magic' SPI to be used.
     71  *
     72  * This allows per-host granularity without affecting the userland
     73  * interface, which is a simple socket option toggle switch,
     74  * TCP_SIGNATURE_ENABLE.
     75  *
     76  * To allow per-service granularity requires that we have a means
     77  * of mapping port to SPI. The mandated way of doing this is to
     78  * use SPD entries to specify packet flows which get the TCP-MD5
     79  * treatment, however the code to do this is currently unstable
     80  * and unsuitable for production use.
     81  *
     82  * Therefore we use this compromise in the meantime.
     83  */
     84 static int
     85 tcpsignature_init(struct secasvar *sav, const struct xformsw *xsp)
     86 {
     87 	int keylen;
     88 
     89 	if (sav->spi != htonl(TCP_SIG_SPI)) {
     90 		DPRINTF("SPI %x must be TCP_SIG_SPI (0x1000)\n", sav->alg_auth);
     91 		return EINVAL;
     92 	}
     93 	if (sav->alg_auth != SADB_X_AALG_TCP_MD5) {
     94 		DPRINTF("unsupported authentication algorithm %u\n",
     95 		    sav->alg_auth);
     96 		return EINVAL;
     97 	}
     98 	if (sav->key_auth == NULL) {
     99 		DPRINTF("no authentication key present\n");
    100 		return EINVAL;
    101 	}
    102 	keylen = _KEYLEN(sav->key_auth);
    103 	if ((keylen < TCP_KEYLEN_MIN) || (keylen > TCP_KEYLEN_MAX)) {
    104 		DPRINTF("invalid key length %u\n", keylen);
    105 		return EINVAL;
    106 	}
    107 
    108 	return 0;
    109 }
    110 
    111 static void
    112 tcpsignature_zeroize(struct secasvar *sav)
    113 {
    114 	if (sav->key_auth) {
    115 		explicit_memset(_KEYBUF(sav->key_auth), 0,
    116 		    _KEYLEN(sav->key_auth));
    117 	}
    118 
    119 	sav->tdb_cryptoid = 0;
    120 	sav->tdb_authalgxform = NULL;
    121 	sav->tdb_xform = NULL;
    122 }
    123 
    124 static int
    125 tcpsignature_input(struct mbuf *m, struct secasvar *sav, int skip,
    126     int protoff)
    127 {
    128 	panic("%s: should not have been called", __func__);
    129 }
    130 
    131 static int
    132 tcpsignature_output(struct mbuf *m, const struct ipsecrequest *isr,
    133     struct secasvar *sav, int skip, int protoff, int flags)
    134 {
    135 	panic("%s: should not have been called", __func__);
    136 }
    137 
    138 static struct xformsw tcpsignature_xformsw = {
    139 	.xf_type	= XF_TCPSIGNATURE,
    140 	.xf_flags	= XFT_AUTH,
    141 	.xf_name	= "TCPMD5",
    142 	.xf_init	= tcpsignature_init,
    143 	.xf_zeroize	= tcpsignature_zeroize,
    144 	.xf_input	= tcpsignature_input,
    145 	.xf_output	= tcpsignature_output,
    146 	.xf_next	= NULL,
    147 };
    148 
    149 void
    150 tcpsignature_attach(void)
    151 {
    152 	xform_register(&tcpsignature_xformsw);
    153 }
    154