summaryrefslogtreecommitdiff
path: root/source3/lib/genrand.c
blob: c4fb925a75b1065acb32068623359f3a3aa2adce (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
/* 
   Unix SMB/Netbios implementation.
   Version 2.2

   Functions to create reasonable random numbers for crypto use.

   Copyright (C) Jeremy Allison 2001
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

extern int DEBUGLEVEL;


static unsigned char hash[258];
static uint32 counter;
unsigned char *reseed_data;
size_t reseed_data_size;

/**************************************************************** 
 Copy any user given reseed data.
*****************************************************************/

void set_rand_reseed_data(unsigned char *data, size_t len)
{
	SAFE_FREE(reseed_data);
	reseed_data_size = 0;

	reseed_data = (unsigned char *)memdup(data, len);
	if (reseed_data)
		reseed_data_size = len;
}

/**************************************************************** 
 Setup the seed.
*****************************************************************/

static void seed_random_stream(unsigned char *seedval, size_t seedlen)
{
	unsigned char j = 0;
	size_t ind;

	for (ind = 0; ind < 256; ind++)
		hash[ind] = (unsigned char)ind;

	for( ind = 0; ind < 256; ind++) {
		unsigned char tc;

		j += (hash[ind] + seedval[ind%seedlen]);

		tc = hash[ind];
		hash[ind] = hash[j];
		hash[j] = tc;
	}

	hash[256] = 0;
	hash[257] = 0;
}

/**************************************************************** 
 Get datasize bytes worth of random data.
*****************************************************************/

static void get_random_stream(unsigned char *data, size_t datasize)
{
	unsigned char index_i = hash[256];
	unsigned char index_j = hash[257];
	size_t ind;

	for( ind = 0; ind < datasize; ind++) {
		unsigned char tc;
		unsigned char t;

		index_i++;
		index_j += hash[index_i];

		tc = hash[index_i];
		hash[index_i] = hash[index_j];
		hash[index_j] = tc;

		t = hash[index_i] + hash[index_j];
		data[ind] = hash[t];
	}

	hash[256] = index_i;
	hash[257] = index_j;
}

/****************************************************************
 Get a 16 byte hash from the contents of a file.
 Note that the hash is not initialised.
*****************************************************************/

static void do_filehash(char *fname, unsigned char *the_hash)
{
	unsigned char buf[1011]; /* deliberate weird size */
	unsigned char tmp_md4[16];
	int fd, n;

	fd = sys_open(fname,O_RDONLY,0);
	if (fd == -1)
		return;

	while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
		mdfour(tmp_md4, buf, n);
		for (n=0;n<16;n++)
			the_hash[n] ^= tmp_md4[n];
	}
	close(fd);
}

/**************************************************************
 Try and get a good random number seed. Try a number of
 different factors. Firstly, try /dev/urandom - use if exists.

 We use /dev/urandom as a read of /dev/random can block if
 the entropy pool dries up. This leads clients to timeout
 or be very slow on connect.

 If we can't use /dev/urandom then seed the stream random generator
 above...
**************************************************************/

static int do_reseed(BOOL use_fd, int fd)
{
	unsigned char seed_inbuf[40];
	uint32 v1, v2; struct timeval tval; pid_t mypid;
	struct passwd *pw;

	if (use_fd) {
		if (fd != -1)
			return fd;

		fd = sys_open( "/dev/urandom", O_RDONLY,0);
		if(fd >= 0)
			return fd;
	}

	/* Add in some secret file contents */

	do_filehash("/etc/shadow", &seed_inbuf[0]);
	do_filehash(lp_smb_passwd_file(), &seed_inbuf[16]);

	/*
	 * Add in the root encrypted password.
	 * On any system where security is taken
	 * seriously this will be secret.
	 */

	pw = sys_getpwnam("root");
	if (pw && pw->pw_passwd) {
		size_t i;
		unsigned char md4_tmp[16];
		mdfour(md4_tmp, (unsigned char *)pw->pw_passwd, strlen(pw->pw_passwd));
		for (i=0;i<16;i++)
			seed_inbuf[8+i] ^= md4_tmp[i];
	}

	/*
	 * Add the counter, time of day, and pid.
	 */

	GetTimeOfDay(&tval);
	mypid = sys_getpid();
	v1 = (counter++) + mypid + tval.tv_sec;
	v2 = (counter++) * mypid + tval.tv_usec;

	SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
	SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));

	/*
	 * Add any user-given reseed data.
	 */

	if (reseed_data) {
		size_t i;
		for (i = 0; i < sizeof(seed_inbuf); i++)
			seed_inbuf[i] ^= reseed_data[i % reseed_data_size];
	}

	seed_random_stream(seed_inbuf, sizeof(seed_inbuf));

	return -1;
}

/*******************************************************************
 Interface to the (hopefully) good crypto random number generator.
********************************************************************/

void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now)
{
	static BOOL done_reseed = False;
	static int urand_fd = -1;
	unsigned char md4_buf[64];
	unsigned char tmp_buf[16];
	unsigned char *p;

	if(!done_reseed || do_reseed_now) {
		urand_fd = do_reseed(True, urand_fd);
		done_reseed = True;
	}

	if (urand_fd != -1 && len > 0) {

		if (read(urand_fd, out, len) == len)
			return; /* len bytes of random data read from urandom. */

		/* Read of urand error, drop back to non urand method. */
		close(urand_fd);
		urand_fd = -1;
		do_reseed(False, -1);
		done_reseed = True;
	}

	/*
	 * Generate random numbers in chunks of 64 bytes,
	 * then md4 them & copy to the output buffer.
	 * This way the raw state of the stream is never externally
	 * seen.
	 */

	p = out;
	while(len > 0) {
		int copy_len = len > 16 ? 16 : len;

		get_random_stream(md4_buf, sizeof(md4_buf));
		mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
		memcpy(p, tmp_buf, copy_len);
		p += copy_len;
		len -= copy_len;
	}
}

/*******************************************************************
 Use the random number generator to generate a random string.
********************************************************************/

static char c_list[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";

char *generate_random_str(size_t len)
{
	static unsigned char retstr[256];
	size_t i;

	memset(retstr, '\0', sizeof(retstr));

	if (len > sizeof(retstr)-1)
		len = sizeof(retstr) -1;
	generate_random_buffer( retstr, len, False);
	for (i = 0; i < len; i++)
		retstr[i] = c_list[ retstr[i] % sizeof(c_list) ];

	retstr[i] = '\0';

	return (char *)retstr;
}