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
|
/*
Unix SMB/Netbios implementation.
Version 1.9.
Functions to create reasonable random numbers for crypto use.
Copyright (C) Jeremy Allison 1998
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 uint32 counter = 0;
/****************************************************************
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 *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++)
hash[n] ^= tmp_md4[n];
}
close(fd);
}
/****************************************************************
Try and get a seed by looking at the atimes of files in a given
directory. XOR them into the buf array.
*****************************************************************/
static void do_dirrand(char *name, unsigned char *buf, int buf_len)
{
DIR *dp = opendir(name);
pstring fullname;
int len_left;
int fullname_len;
char *pos;
pstrcpy(fullname, name);
fullname_len = strlen(fullname);
if(fullname_len + 2 > sizeof(pstring))
return;
if(fullname[fullname_len] != '/') {
fullname[fullname_len] = '/';
fullname[fullname_len+1] = '\0';
fullname_len = strlen(fullname);
}
len_left = sizeof(pstring) - fullname_len - 1;
pos = &fullname[fullname_len];
if(dp != NULL) {
char *p;
while ((p = readdirname(dp))) {
SMB_STRUCT_STAT st;
if(strlen(p) <= len_left)
pstrcpy(pos, p);
if(sys_stat(fullname,&st) == 0) {
SIVAL(buf, ((counter * 4)%(buf_len-4)),
IVAL(buf,((counter * 4)%(buf_len-4))) ^ st.st_atime);
counter++;
DEBUG(10,("do_dirrand: value from file %s.\n", fullname));
}
}
closedir(dp);
}
}
/**************************************************************
Try and get a good random number seed. Try a number of
different factors. Firstly, try /dev/urandom and try and
read from this. If this fails iterate through /tmp and
/dev and XOR all the file timestamps. Next add in
a hash of the contents of /etc/shadow and the smb passwd
file and a combination of pid and time of day (yes I know this
sucks :-). Finally md4 the result.
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.
The result goes in a 16 byte buffer passed from the caller
**************************************************************/
static uint32 do_reseed(unsigned char *md4_outbuf)
{
unsigned char md4_inbuf[40];
BOOL got_random = False;
uint32 v1, v2, ret;
int fd;
struct timeval tval;
pid_t mypid;
struct passwd *pw;
memset(md4_inbuf, '\0', sizeof(md4_inbuf));
fd = sys_open( "/dev/urandom", O_RDONLY,0);
if(fd >= 0) {
/*
* We can use /dev/urandom !
*/
if(read(fd, md4_inbuf, 40) == 40) {
got_random = True;
DEBUG(10,("do_reseed: got 40 bytes from /dev/urandom.\n"));
}
close(fd);
}
if(!got_random) {
/*
* /dev/urandom failed - try /dev for timestamps.
*/
do_dirrand("/dev", md4_inbuf, sizeof(md4_inbuf));
}
/* possibly add in some secret file contents */
do_filehash("/etc/shadow", &md4_inbuf[0]);
do_filehash(lp_smb_passwd_file(), &md4_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) {
int i;
unsigned char md4_tmp[16];
mdfour(md4_tmp, (unsigned char *)pw->pw_passwd, strlen(pw->pw_passwd));
for (i=0;i<16;i++)
md4_inbuf[8+i] ^= md4_tmp[i];
}
/*
* Finally add the counter, time of day, and pid.
*/
GetTimeOfDay(&tval);
mypid = getpid();
v1 = (counter++) + mypid + tval.tv_sec;
v2 = (counter++) * mypid + tval.tv_usec;
SIVAL(md4_inbuf, 32, v1 ^ IVAL(md4_inbuf, 32));
SIVAL(md4_inbuf, 36, v2 ^ IVAL(md4_inbuf, 36));
mdfour(md4_outbuf, md4_inbuf, sizeof(md4_inbuf));
/*
* Return a 32 bit int created from XORing the
* 16 bit return buffer.
*/
ret = IVAL(md4_outbuf, 0);
ret ^= IVAL(md4_outbuf, 4);
ret ^= IVAL(md4_outbuf, 8);
return (ret ^ IVAL(md4_outbuf, 12));
}
/*******************************************************************
Interface to the (hopefully) good crypto random number generator.
********************************************************************/
void generate_random_buffer( unsigned char *out, int len, BOOL re_seed)
{
static BOOL done_reseed = False;
static unsigned char md4_buf[16];
unsigned char tmp_buf[16];
unsigned char *p;
if(!done_reseed || re_seed) {
sys_srandom(do_reseed(md4_buf));
done_reseed = True;
}
/*
* Generate random numbers in chunks of 64 bytes,
* then md4 them & copy to the output buffer.
* Added XOR with output from random, seeded
* by the original md4_buf. This is to stop the
* output from this function being the previous
* md4_buf md4'ed. The output from this function
* is often output onto the wire, and so it should
* not be possible to guess the next output from
* this function based on the previous output.
* XORing in the output from random(), seeded by
* the original md4 hash should stop this. JRA.
*/
p = out;
while(len > 0) {
int i;
int copy_len = len > 16 ? 16 : len;
mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
memcpy(md4_buf, tmp_buf, sizeof(md4_buf));
/* XOR in output from random(). */
for(i = 0; i < 4; i++)
SIVAL(tmp_buf, i*4, (IVAL(tmp_buf, i*4) ^ (uint32)sys_random()));
memcpy(p, tmp_buf, copy_len);
p += copy_len;
len -= copy_len;
}
}
|
