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
|
/* vi: set sw=4 ts=4:
*
* passwd.c - Program to upadte user password.
*
* Copyright 2012 Ashwini Kumar <ak.ashwini@gmail.com>
* Modified 2012 Jason Kyungwan Han <asura321@gmail.com>
*
* Not in SUSv4.
USE_PASSWD(NEWTOY(passwd, ">1a:dlu", TOYFLAG_STAYROOT|TOYFLAG_USR|TOYFLAG_BIN))
config PASSWD
bool "passwd"
default y
help
usage: passwd [-a ALGO] [-d] [-l] [-u] <account name>
update user’s authentication tokens. Default : current user
-a ALGO Encryption method (des, md5, sha256, sha512) default: des
-d Set password to ''
-l Lock (disable) account
-u Unlock (enable) account
*/
#include "toys.h"
#include <time.h>
DEFINE_GLOBALS(
char *algo;
)
#define TT this.passwd
#define FLAG_u (1 << 0)
#define FLAG_l (1 << 1)
#define FLAG_d (1 << 2)
#define FLAG_a (1 << 3)
#define MAX_SALT_LEN 20 //3 for id, 16 for key, 1 for '\0'
#define URANDOM_PATH "/dev/urandom"
#ifndef _GNU_SOURCE
char *strcasestr(const char *haystack, const char *needle);
#endif
unsigned int random_number_generator(int fd)
{
unsigned int randnum;
xreadall(fd, &randnum, sizeof(randnum));
return randnum;
}
char inttoc(int i)
{
// salt value uses 64 chracters in "./0-9a-zA-Z"
const char character_set[]="./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
i &= 0x3f; // masking for using 10 bits only
return character_set[i];
}
int get_salt(char *salt)
{
int i, salt_length = 0;
int randfd;
if(!strncmp(TT.algo,"des",3)){
// 2 bytes salt value is used in des
salt_length = 2;
} else {
*salt++ = '$';
if(!strncmp(TT.algo,"md5",3)){
*salt++ = '1';
// 8 bytes salt value is used in md5
salt_length = 8;
} else if(!strncmp(TT.algo,"sha256",6)){
*salt++ = '5';
// 16 bytes salt value is used in sha256
salt_length = 16;
} else if(!strncmp(TT.algo,"sha512",6)){
*salt++ = '6';
// 16 bytes salt value is used in sha512
salt_length = 16;
} else return 1;
*salt++ = '$';
}
randfd = xopen(URANDOM_PATH, O_RDONLY);
for(i=0; i<salt_length; i++)
salt[i] = inttoc(random_number_generator(randfd));
salt[salt_length+1] = '\0';
xclose(randfd);
return 0;
}
static int str_check(char *s, char *p)
{
if((strcasestr(s, p) != NULL) || (strcasestr(p, s) != NULL))
return 1;
return 0;
}
static void strength_check(char *newp, char *oldp, char *user)
{
char *msg = NULL;
if(strlen(newp) < 6) { //Min passwd len
msg = "too short";
xprintf("BAD PASSWORD: %s\n",msg);
}
if(!newp[0])
return; //passwd is empty
if(str_check(newp, user)) {
msg = "user based password";
xprintf("BAD PASSWORD: %s\n",msg);
}
if(oldp[0] && str_check(newp, oldp)) {
msg = "based on old passwd";
xprintf("BAD PASSWORD: %s\n",msg);
}
}
static int verify_passwd(char * pwd)
{
char * pass;
if (!pwd) return 1;
if (pwd[0] == '!' || pwd[0] == '*') return 1;
pass = crypt(toybuf, pwd);
if (pass != NULL && strcmp(pass, pwd)==0)
return 0;
return 1;
}
static char *new_password(char *oldp, char *user)
{
char *newp = NULL;
if(read_password(toybuf, sizeof(toybuf), "New password:"))
return NULL; //may be due to Ctrl-C
newp = xstrdup(toybuf);
strength_check(newp, oldp, user);
if(read_password(toybuf, sizeof(toybuf), "Retype password:")) {
free(newp);
return NULL; //may be due to Ctrl-C
}
if(strcmp(newp, toybuf) == 0)
return newp;
else error_msg("Passwords do not match.\n");
/*Failure Case */
free(newp);
return NULL;
}
void passwd_main(void)
{
uid_t myuid;
struct passwd *pw;
struct spwd *sp;
char *name = NULL;
char *pass = NULL, *encrypted = NULL, *newp = NULL;
char *orig = (char *)"";
char salt[MAX_SALT_LEN];
int ret = -1;
myuid = getuid();
if((myuid != 0) && (toys.optflags & (FLAG_l | FLAG_u | FLAG_d)))
error_exit("You need to be root to do these actions\n");
pw = getpwuid(myuid);
if(!pw)
error_exit("Unknown uid '%u'",myuid);
if(toys.optargs[0])
name = toys.optargs[0];
else
name = xstrdup(pw->pw_name);
pw = getpwnam(name);
if(!pw) error_exit("Unknown user '%s'",name);
if(myuid != 0 && (myuid != pw->pw_uid))
error_exit("You need to be root to change '%s' password\n", name);
pass = pw->pw_passwd;
if(pw->pw_passwd[0] == 'x') {
/*get shadow passwd */
sp = getspnam(name);
if(sp)
pass = sp->sp_pwdp;
}
if(!(toys.optflags & (FLAG_l | FLAG_u | FLAG_d))) {
printf("Changing password for %s\n",name);
if(pass[0] == '!')
error_exit("Can't change, password is locked for %s",name);
if(myuid != 0) {
/*Validate user */
if(read_password(toybuf, sizeof(toybuf), "Origial password:")) {
if(!toys.optargs[0]) free(name);
return;
}
orig = toybuf;
if(verify_passwd(pass))
error_exit("Authentication failed\n");
}
orig = xstrdup(orig);
/*Get new password */
newp = new_password(orig, name);
if(!newp) {
free(orig);
if(!toys.optargs[0]) free(name);
return; //new password is not set well.
}
/*Encrypt the passwd */
if(!(toys.optflags & FLAG_a)) TT.algo = "des";
if(get_salt(salt))
error_exit("Error: Unkown encryption algorithm\n");
encrypted = crypt(newp, salt);
free(newp);
free(orig);
}
else if(toys.optflags & FLAG_l) {
if(pass[0] == '!')
error_exit("password is already locked for %s",name);
printf("Locking password for %s\n",name);
encrypted = xmsprintf("!%s",pass);
}
else if(toys.optflags & FLAG_u) {
if(pass[0] != '!')
error_exit("password is already unlocked for %s",name);
printf("Unlocking password for %s\n",name);
encrypted = xstrdup(&pass[1]);
}
else if(toys.optflags & FLAG_d) {
printf("Deleting password for %s\n",name);
encrypted = (char*)xzalloc(sizeof(char)*2); //1 = "", 2 = '\0'
}
/*Update the passwd */
if(pw->pw_passwd[0] == 'x')
ret = update_password("/etc/shadow", name, encrypted);
else
ret = update_password("/etc/passwd", name, encrypted);
if((toys.optflags & (FLAG_l | FLAG_u | FLAG_d)))
free(encrypted);
if(!toys.optargs[0]) free(name);
if(!ret)
error_msg("Success");
else
error_msg("Failure");
}
|
