summaryrefslogtreecommitdiffstats
path: root/ax25/access.c
blob: 951830c96bd46466b14b19ab6353beb91f4205af (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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>
#include <limits.h>
#include <pwd.h>
#include <fcntl.h>

#include "access.h"
#include "md5.h"
#include "axspawn.h"

#define CONV_RAND_MAX 0x7fffffff

#define	SYSTEMPW 0
#define	USERPW	 1

static long seed = 1L;

/*--------------------------------------------------------------------------*/

static int conv_rand(void)
{
	seed = (1103515245L * seed + 12345) & CONV_RAND_MAX;
	return (int) (seed & 077777);
}

/*--------------------------------------------------------------------------*/

static void conv_randomize(void)
{
	seed = (time(NULL) & CONV_RAND_MAX);
}

/*--------------------------------------------------------------------------*/

static int conv_random(int num, int base)
{
	return ((long) (conv_rand() * time(NULL)) & CONV_RAND_MAX) % num + base;
}

/*--------------------------------------------------------------------------*/

static void char_to_hex(char *c, char *h, int n)
{

	int  i;
	static char  *hextable = "0123456789abcdef";

	for (i = 0; i < n; i++) {
		*h++ = hextable[(*c>>4)&0xf];
		*h++ = hextable[*c++ &0xf];
	}
	*h = '\0';
}

/*--------------------------------------------------------------------------*/

static char *generate_rand_pw(int len)
{
	static char pass[PASSSIZE+1];
	int i, j;

	pass[0] = 0;

	if (seed == 1L)
		conv_randomize();

	if (len < 1)
		return pass;

	if (len > PASSSIZE)
		len = PASSSIZE;

	for (i = 0; i < len; i++) {
		j = conv_random(10+26*2, 0);
		if (j < 10) {
			pass[i] = j + '0';
			continue;
		}
		j -= 10;
		if (j < 26) {
			pass[i] = j + 'A';
			continue;
		}
		j -= 26;
		pass[i] = j + 'a';
	}
	pass[len] = 0;

	return pass;
}

/*--------------------------------------------------------------------------*/

static void calc_md5_pw (const char *MD5prompt, const char *MD5pw,
	char *MD5result)
{
	MD5_CTX context;
	short i, n, len;
	char buffer[1024];

	strncpy(buffer, MD5prompt, 10);
	buffer[10] = 0;
	strcat(buffer, MD5pw);

	MD5Init(&context);

	len = strlen(buffer);
	for (i= 0; i < len; i += 16) {
		n = (len - i) > 16 ? 16 : (len - i);
		MD5Update(&context, (unsigned char *) buffer+i, n);
	}

	MD5Final(&context);

	MD5result[0] = '\0';
	for (i = 0; i < 16; i++) {
		MD5result[i] = context.digest[i];
	}
}

/*--------------------------------------------------------------------------*/

void ask_pw_sys(char *prompt, char *pass_want, char *pw)
{
	char buffer[2048];
	int five_digits[5];
	int pwlen;
	int i, j;

	pass_want[0]= 0;

	if (!pw || !*pw)
		return;

	pwlen = strlen(pw);

	if (seed == 1L)
		conv_randomize();

	for (i = 0; i < 5; i++) {
		int k;
again:
		j = conv_random(pwlen, 0);
		/* store generated request-numbers  */
		five_digits[i] = j+1; /* pos0 refers as 1  */
		/* same number again? */
		for (k = 0; k < i; k++) {
			if (five_digits[k] == five_digits[i])
				goto again;
		}
		/* store expected string in cp->passwd  */
		pass_want[i] = pw[j];
	}
	/* and terminate the string  */
	pass_want[i] = 0;

	sprintf(buffer, "\r%s>  %d %d %d %d %d\r", prompt, five_digits[0], five_digits[1], five_digits[2], five_digits[3], five_digits[4]);
	write_ax25(buffer, strlen(buffer), 1);
}

/*--------------------------------------------------------------------------*/

void ask_pw_md5(char *prompt, char *pass_want, char *pw)
{
#define	SALT_LEN	10
	char buffer[2048];
	char cipher[16];
	char key[256];
	char *challenge;

	pass_want[0]= 0;

	if (!pw || !*pw)
		return;

	if (seed == 1L)
		conv_randomize();

	strncpy(key, pw, sizeof(key));
	key[sizeof(key)-1] = 0;

	/* compute random salt  */
	challenge = generate_rand_pw(SALT_LEN);

	/* ask for proper response to this challenge:  */
	sprintf(buffer, "\r%s> [%s]\r", prompt, challenge);
	write_ax25(buffer, strlen(buffer), 1);
	/* compute md5 challenge  */
	calc_md5_pw(challenge, key, cipher);
	/* store expected answer  */
	char_to_hex(cipher, pass_want, 16);
}

/*--------------------------------------------------------------------------*/

static void write_example_passwd(char *pwfile, char pwlocation,
	struct passwd *pw)
{
	FILE * f;
	int i;

	if ((i = open(pwfile, O_CREAT|O_WRONLY|O_TRUNC, (S_IRUSR | S_IWUSR | (pwlocation == SYSTEMPW ? (S_IRGRP /* | S_IWGRP */ ) : 0)))) == -1)
		return;
	fchown(i, (pwlocation == SYSTEMPW ? 0 : pw->pw_uid), (pwlocation == SYSTEMPW ? 0 : pw->pw_gid));
	close(i);
	if ( ! (f = fopen(pwfile, "w")) )
		return;
	fprintf(f, "# %s Password file for axspawn\n", (pwlocation == SYSTEMPW ? "System" : "User"));
	if (pwlocation == SYSTEMPW) {
		fprintf(f, "# disable user self-administered passwords in $HOME/.%s\n", PWFILE);
		fprintf(f, "# with the line \"systempasswordonly\"\n");
		fprintf(f, "# systempasswordonly\n");
	}
	fprintf(f, "# Examples (sys and md5 passwords may differ):\n");
	fprintf(f, "# md5 standard (secure) - length: >= %d and <= %d characters\n", MINPWLEN_MD5, PASSSIZE);
	fprintf(f, "# %smd5:%s\n", (pwlocation == SYSTEMPW ? "username:" : ""), generate_rand_pw(MINPWLEN_MD5));
	fprintf(f, "# sys/baycom standard (not very secure) - length: >= %d and <= %d characters\n", MINPWLEN_SYS, PASSSIZE);
	fprintf(f, "# %ssys:%s\n", (pwlocation == SYSTEMPW ? "username:" : ""), generate_rand_pw(MINPWLEN_SYS));
	fprintf(f, "# unix standard (plaintext): no password is read here. Your password is looked\n");
	fprintf(f, "#   up during login in the system password table /etc/passwd or /etc/shadow\n");
	fprintf(f, "# unix\n");
	fclose(f);
}

/*--------------------------------------------------------------------------*/

char *read_pwd (struct passwd *pw, int *pwtype)
{
	FILE * f = NULL;
	struct stat statbuf;
	char pwfile[PATH_MAX + 1];
	int len;
	char pwlocation;
	char buf[2048];
	int only_systempw = 0;
	char *pass = NULL;
	char *p_buf;
	char *p;


	for (pwlocation = 0; pwlocation < 2; pwlocation++) {

		if (pwlocation == SYSTEMPW) {
			sprintf(pwfile, "/%s/%s", AX25_SYSCONFDIR, PWFILE);
			if (stat(pwfile, &statbuf)) {
				write_example_passwd(pwfile, pwlocation, pw);
				continue;
			}
			if (!S_ISREG(statbuf.st_mode) || (statbuf.st_mode & (S_IROTH | S_IWOTH)))
				continue;
			if ( !(f = fopen(pwfile, "r")) )
				continue;
		} else {
			if (only_systempw)
				goto end;
			snprintf(pwfile, sizeof(pwfile), "%s/.%s", pw->pw_dir, PWFILE);
			pwfile[sizeof(pwfile)-1] = 0;

			if (stat(pwfile, &statbuf)) {
				sprintf(buf, "Notice: No .%s file found in your homedirectory (for more secure\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "        password authentication than plaintext). Generating example file,\r");
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "        with unique passwords (which may be changed).\r");
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "        Please edit ~/.%s, and enable your prefered authentication type;\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "        MD5 is recommended.\r");
				write_ax25(buf, strlen(buf), 1);
				write_example_passwd(pwfile, pwlocation, pw);
				goto end;
			}
			if (!S_ISREG(statbuf.st_mode)) {
				sprintf(buf, "Error: password file .%s should be a regular file. Skiping..\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				goto end;
			}
			if (statbuf.st_uid != 0 && statbuf.st_uid != pw->pw_uid) {
				sprintf(buf, "Error: your password file .%s is not owned by you. Skiping..\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				goto end;
			}
			if  ((statbuf.st_mode & (S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH))) {
				sprintf(buf, "WARNING: your password file .%s has wrong permissions.\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "         Please change it with\r");
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "           chmod 600 .%s\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "         and don't forget to change your password stored in .%s\r", PWFILE);
				write_ax25(buf, strlen(buf), 1);
				sprintf(buf, "         because it may be compromised.\r");
				write_ax25(buf, strlen(buf), 1);
				/* go on.. if user takes no action, he always gets this message */
			}
			if ( !(f = fopen(pwfile, "r")) )
				goto end;
		}


		for (;;) {
			if (!fgets(buf, sizeof(buf), f)) {
				fclose(f);
				if (pwlocation == SYSTEMPW)
					break;
				/* perhaps this is too irritating for the user
				   when the message occurs always. Thus only
				   write the notice, if cleartext fallback
				   is disabled by administrative configuration.
				 */
				if  (!((*pwtype) & PW_CLEARTEXT)) {
					sprintf(buf, "Failed to find a suitable password in %s\r", pwfile);
					write_ax25(buf, strlen(buf), 1);
				}
				goto end;
			}
			if ((p = strchr(buf, '\n')))
				*p = 0;
			if (!*buf || isspace(*buf & 0xff))
				continue;
			if (*buf == '#')
				continue;
			if (pwlocation == SYSTEMPW) {
				if (!Strcasecmp(buf, "systempasswordonly")) {
					only_systempw = 1;
					continue;
				}
				if (!(p = strchr(buf, ':')))
					continue;
				*p++ = 0;
				if (strcmp(pw->pw_name, buf))
					continue;
				p_buf = p;
			} else {
				p_buf = buf;
			}

			if (!Strcasecmp(p_buf, "unix")) {
				pass = p_buf;
			} else {
				if (!(pass = strchr(p_buf, ':')))
					continue;
				*pass++ = 0;
			}

			while (*pass && isspace(*pass & 0xff))
				pass++;
			for (p = pass; *p && !isspace(*p & 0xff); p++) ;
			*p = 0;

			if ( (*pwtype & PW_MD5) && !Strcasecmp(p_buf, "md5") ) {
				fclose(f);
				*pwtype = PW_MD5;
				goto found;
			} else if ( (*pwtype & PW_SYS) && (!Strcasecmp(p_buf, "sys") || !strcmp(p_buf, "baycom")) ) {
				fclose(f);
				*pwtype = PW_SYS;
				goto found;
			} else if ( (*pwtype & PW_UNIX) &&  (!Strcasecmp(p_buf, "unix") ) ) {
				fclose(f);
				*pwtype = PW_UNIX;
				return NULL;
			}
		}
	}
found:

	if (!pass || !*pwtype)
		goto end;

	len = strlen(pass);

	if ((*pwtype == PW_SYS && len < MINPWLEN_SYS) || (*pwtype == PW_MD5 && len < MINPWLEN_MD5)) {
		sprintf(buf, "Password in password file too short\r");
		write_ax25(buf, strlen(buf), 1);
		goto end;
	}
	if (strlen(pass) > PASSSIZE)
		pass[PASSSIZE] = 0;

	return strdup(pass);

end:
	*pwtype = (((*pwtype) & PW_CLEARTEXT) ? PW_CLEARTEXT : 0);
		   /*         ^ may allow cleartext? - then cleartext, else deny */
	return NULL;
}