1/*
2 * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska H�gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
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 *
17 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *      This product includes software developed by the Kungliga Tekniska
20 *      H�gskolan and its contributors.
21 *
22 * 4. Neither the name of the Institute nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#include "sasl_mac_krb_locl.h"
40
41RCSID("$Id: rd_safe.c,v 1.4 2005/01/10 19:10:47 snsimon Exp $");
42
43/* application include files */
44#include "krb-archaeology.h"
45
46/* Generate two checksums in the given byteorder of the data, one
47 * new-form and one old-form. It has to be done this way to be
48 * compatible with the old version of des_quad_cksum.
49 */
50
51/* des_quad_chsum-type; 0 == unknown, 1 == new PL10++, 2 == old */
52int dqc_type = DES_QUAD_DEFAULT;
53
54void
55fixup_quad_cksum(void *start, size_t len, des_cblock *key,
56		 void *new_checksum, void *old_checksum, int little)
57{
58    des_quad_cksum((des_cblock*)start, (des_cblock*)new_checksum, len, 2, key);
59    if(HOST_BYTE_ORDER){
60	if(little){
61	    memcpy(old_checksum, new_checksum, 16);
62	}else{
63	    u_int32_t *tmp = (u_int32_t*)new_checksum;
64	    memcpy(old_checksum, new_checksum, 16);
65	    swap_u_16(old_checksum);
66	    swap_u_long(tmp[0]);
67	    swap_u_long(tmp[1]);
68	    swap_u_long(tmp[2]);
69	    swap_u_long(tmp[3]);
70	}
71    }else{
72	if(little){
73	    u_int32_t *tmp = (u_int32_t*)new_checksum;
74	    swap_u_long(tmp[0]);
75	    swap_u_long(tmp[1]);
76	    swap_u_long(tmp[2]);
77	    swap_u_long(tmp[3]);
78	    memcpy(old_checksum, new_checksum, 16);
79	}else{
80	    u_int32_t tmp[4];
81	    tmp[0] = ((u_int32_t*)new_checksum)[3];
82	    tmp[1] = ((u_int32_t*)new_checksum)[2];
83	    tmp[2] = ((u_int32_t*)new_checksum)[1];
84	    tmp[3] = ((u_int32_t*)new_checksum)[0];
85	    memcpy(old_checksum, tmp, 16);
86	}
87    }
88}
89
90/*
91 * krb_rd_safe() checks the integrity of an AUTH_MSG_SAFE message.
92 * Given the message received, "in", the length of that message,
93 * "in_length", the "key" to compute the checksum with, and the
94 * network addresses of the "sender" and "receiver" of the message,
95 * krb_rd_safe() returns RD_AP_OK if message is okay, otherwise
96 * some error code.
97 *
98 * The message data retrieved from "in" is returned in the structure
99 * "m_data".  The pointer to the application data (m_data->app_data)
100 * refers back to the appropriate place in "in".
101 *
102 * See the file "mk_safe.c" for the format of the AUTH_MSG_SAFE
103 * message.  The structure containing the extracted message
104 * information, MSG_DAT, is defined in "krb.h".
105 */
106
107int32_t
108krb_rd_safe(void *in, u_int32_t in_length, des_cblock *key,
109	    struct sockaddr_in *sender, struct sockaddr_in *receiver,
110	    MSG_DAT *m_data)
111{
112    unsigned char *p = (unsigned char*)in, *start;
113
114    unsigned char pvno, type;
115    int little_endian;
116    struct timeval tv;
117    u_int32_t src_addr;
118    int delta_t;
119
120
121    pvno = *p++;
122    if(pvno != KRB_PROT_VERSION)
123	return RD_AP_VERSION;
124
125    type = *p++;
126    little_endian = type & 1;
127    type &= ~1;
128    if(type != AUTH_MSG_SAFE)
129	return RD_AP_MSG_TYPE;
130
131    start = p;
132
133    p += krb_get_int(p, &m_data->app_length, 4, little_endian);
134
135    if(m_data->app_length + 31 > in_length)
136	return RD_AP_MODIFIED;
137
138    m_data->app_data = p;
139
140    p += m_data->app_length;
141
142    m_data->time_5ms = *p++;
143
144    p += krb_get_address(p, &src_addr);
145
146    if (!krb_equiv(src_addr, sender->sin_addr.s_addr))
147        return RD_AP_BADD;
148
149    p += krb_get_int(p, (u_int32_t *)&m_data->time_sec, 4, little_endian);
150    m_data->time_sec = lsb_time(m_data->time_sec, sender, receiver);
151
152    gettimeofday(&tv, NULL);
153
154    delta_t = abs((int)((long) tv.tv_sec - m_data->time_sec));
155    if (delta_t > CLOCK_SKEW) return RD_AP_TIME;
156
157    /*
158     * caller must check timestamps for proper order and replays, since
159     * server might have multiple clients each with its own timestamps
160     * and we don't assume tightly synchronized clocks.
161     */
162
163    {
164	unsigned char new_checksum[16];
165	unsigned char old_checksum[16];
166	fixup_quad_cksum(start, p - start, key,
167			 new_checksum, old_checksum, little_endian);
168	if((dqc_type == DES_QUAD_GUESS || dqc_type == DES_QUAD_NEW) &&
169	   memcmp(new_checksum, p, 16) == 0)
170	    dqc_type = DES_QUAD_NEW;
171	else if((dqc_type == DES_QUAD_GUESS || dqc_type == DES_QUAD_OLD) &&
172		memcmp(old_checksum, p, 16) == 0)
173	    dqc_type = DES_QUAD_OLD;
174	else
175	    return RD_AP_MODIFIED;
176    }
177    return KSUCCESS;
178}
179