summaryrefslogtreecommitdiffstats
path: root/eBones/krb/rd_safe.c
blob: e500b4deba0bc78900fffbb43bf760501a074e8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
/*
 * Copyright 1986, 1987, 1988 by the Massachusetts Institute
 * of Technology.
 * For copying and distribution information, please see the file
 * <Copyright.MIT>.
 *
 * This routine dissects a a Kerberos 'safe msg', checking its
 * integrity, and returning a pointer to the application data
 * contained and its length.
 *
 * Returns 0 (RD_AP_OK) for success or an error code (RD_AP_...)
 *
 * Steve Miller    Project Athena  MIT/DEC
 *
 *	from: rd_safe.c,v 4.12 89/01/23 15:16:16 steiner Exp $
 *	$Id: rd_safe.c,v 1.2 1994/07/19 19:26:15 g89r4222 Exp $
 */

#ifndef lint
static char rcsid[] =
"$Id: rd_safe.c,v 1.2 1994/07/19 19:26:15 g89r4222 Exp $";
#endif /* lint */

/* system include files */
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/time.h>

/* application include files */
#include <des.h>
#include <krb.h>
#include <prot.h>
#include "lsb_addr_comp.h"

extern char *errmsg();
extern int errno;
extern int krb_debug;

/* static storage */

static C_Block calc_cksum[2];
static C_Block big_cksum[2];
static int swap_bytes;
static struct timeval local_time;
static u_long delta_t;

/*
 * krb_rd_safe() checks the integrity of an AUTH_MSG_SAFE message.
 * Given the message received, "in", the length of that message,
 * "in_length", the "key" to compute the checksum with, and the
 * network addresses of the "sender" and "receiver" of the message,
 * krb_rd_safe() returns RD_AP_OK if message is okay, otherwise
 * some error code.
 *
 * The message data retrieved from "in" is returned in the structure
 * "m_data".  The pointer to the application data (m_data->app_data)
 * refers back to the appropriate place in "in".
 *
 * See the file "mk_safe.c" for the format of the AUTH_MSG_SAFE
 * message.  The structure containing the extracted message
 * information, MSG_DAT, is defined in "krb.h".
 */

long krb_rd_safe(in,in_length,key,sender,receiver,m_data)
    u_char *in;                 /* pointer to the msg received */
    u_long in_length;           /* length of "in" msg */
    C_Block *key;               /* encryption key for seed and ivec */
    struct sockaddr_in *sender; /* sender's address */
    struct sockaddr_in *receiver; /* receiver's address -- me */
    MSG_DAT *m_data;		/* where to put message information */
{
    register u_char     *p,*q;
    static      u_long  src_addr; /* Can't send structs since no
                                   * guarantees on size */
    /* Be very conservative */
    if (sizeof(u_long) != sizeof(struct in_addr)) {
        fprintf(stderr,"\n\
krb_rd_safe protocol err sizeof(u_long) != sizeof(struct in_addr)");
        exit(-1);
    }

    if (gettimeofday(&local_time,(struct timezone *)0))
        return  -1;

    p = in;                     /* beginning of message */
    swap_bytes = 0;

    if (*p++ != KRB_PROT_VERSION)       return RD_AP_VERSION;
    if (((*p) & ~1) != AUTH_MSG_SAFE) return RD_AP_MSG_TYPE;
    if ((*p++ & 1) != HOST_BYTE_ORDER) swap_bytes++;

    q = p;                      /* mark start of cksum stuff */

    /* safely get length */
    bcopy((char *)p,(char *)&(m_data->app_length),
          sizeof(m_data->app_length));
    if (swap_bytes) swap_u_long(m_data->app_length);
    p += sizeof(m_data->app_length); /* skip over */

    if (m_data->app_length + sizeof(in_length)
        + sizeof(m_data->time_sec) + sizeof(m_data->time_5ms)
        + sizeof(big_cksum) + sizeof(src_addr)
        + VERSION_SZ + MSG_TYPE_SZ > in_length)
        return(RD_AP_MODIFIED);

    m_data->app_data = p;       /* we're now at the application data */

    /* skip app data */
    p += m_data->app_length;

    /* safely get time_5ms */
    bcopy((char *)p, (char *)&(m_data->time_5ms),
          sizeof(m_data->time_5ms));

    /* don't need to swap-- one byte for now */
    p += sizeof(m_data->time_5ms);

    /* safely get src address */
    bcopy((char *)p,(char *)&src_addr,sizeof(src_addr));

    /* don't swap, net order always */
    p += sizeof(src_addr);

    if (src_addr != (u_long) sender->sin_addr.s_addr)
        return RD_AP_MODIFIED;

    /* safely get time_sec */
    bcopy((char *)p, (char *)&(m_data->time_sec),
          sizeof(m_data->time_sec));
    if (swap_bytes)
        swap_u_long(m_data->time_sec);
    p += sizeof(m_data->time_sec);

    /* check direction bit is the sign bit */
    /* For compatibility with broken old code, compares are done in VAX 
       byte order (LSBFIRST) */ 
    if (lsb_net_ulong_less(sender->sin_addr.s_addr,
			   receiver->sin_addr.s_addr)==-1) 
	/* src < recv */ 
	m_data->time_sec =  - m_data->time_sec; 
    else if (lsb_net_ulong_less(sender->sin_addr.s_addr, 
				receiver->sin_addr.s_addr)==0) 
	if (lsb_net_ushort_less(sender->sin_port,receiver->sin_port)==-1)
	    /* src < recv */
	    m_data->time_sec =  - m_data->time_sec; 

    /*
     * All that for one tiny bit!  Heaven help those that talk to
     * themselves.
     */

    /* check the time integrity of the msg */
    delta_t = abs((int)((long) local_time.tv_sec - m_data->time_sec));
    if (delta_t > CLOCK_SKEW) return RD_AP_TIME;

    /*
     * caller must check timestamps for proper order and replays, since
     * server might have multiple clients each with its own timestamps
     * and we don't assume tightly synchronized clocks.
     */

    bcopy((char *)p,(char *)big_cksum,sizeof(big_cksum));
    if (swap_bytes) swap_u_16(big_cksum);

#ifdef NOENCRYPTION
    bzero(calc_cksum, sizeof(calc_cksum));
#else
    quad_cksum(q,calc_cksum,p-q,2,key);
#endif

    if (krb_debug)
        printf("\ncalc_cksum = %u, received cksum = %u",
               (long) calc_cksum[0], (long) big_cksum[0]);
    if (bcmp((char *)big_cksum,(char *)calc_cksum,sizeof(big_cksum)))
        return(RD_AP_MODIFIED);

    return(RD_AP_OK);           /* OK == 0 */
}
OpenPOWER on IntegriCloud