summaryrefslogtreecommitdiff
path: root/loginutils/passwd.c
blob: b0770e65ca21f3e500dee221d1e85b09bfd0549b (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
/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "busybox.h"
#include <syslog.h>

static char crypt_passwd[128];

static int create_backup(const char *backup, FILE * fp);
static int new_password(const struct passwd *pw, int amroot, int algo);
static void set_filesize_limit(int blocks);


static int get_algo(char *a)
{
	int x = 1;					/* standard: MD5 */

	if (strcasecmp(a, "des") == 0)
		x = 0;
	return x;
}


static int update_passwd(const struct passwd *pw, const char *crypt_pw)
{
	char filename[1024];
	char buf[1025];
	char buffer[80];
	char username[32];
	char *pw_rest;
	int mask;
	int continued;
	FILE *fp;
	FILE *out_fp;
	struct stat sb;
	struct flock lock;

#if ENABLE_FEATURE_SHADOWPASSWDS
	if (access(bb_path_shadow_file, F_OK) == 0) {
		snprintf(filename, sizeof filename, "%s", bb_path_shadow_file);
	} else
#endif
	{
		snprintf(filename, sizeof filename, "%s", bb_path_passwd_file);
	}

	if (((fp = fopen(filename, "r+")) == 0) || (fstat(fileno(fp), &sb))) {
		/* return 0; */
		return 1;
	}

	/* Lock the password file before updating */
	lock.l_type = F_WRLCK;
	lock.l_whence = SEEK_SET;
	lock.l_start = 0;
	lock.l_len = 0;
	if (fcntl(fileno(fp), F_SETLK, &lock) < 0) {
		fprintf(stderr, "%s: %s\n", filename, strerror(errno));
		return 1;
	}
	lock.l_type = F_UNLCK;

	snprintf(buf, sizeof buf, "%s-", filename);
	if (create_backup(buf, fp)) {
		fcntl(fileno(fp), F_SETLK, &lock);
		fclose(fp);
		return 1;
	}
	snprintf(buf, sizeof buf, "%s+", filename);
	mask = umask(0777);
	out_fp = fopen(buf, "w");
	umask(mask);
	if ((!out_fp) || (fchmod(fileno(out_fp), sb.st_mode & 0777))
		|| (fchown(fileno(out_fp), sb.st_uid, sb.st_gid))) {
		fcntl(fileno(fp), F_SETLK, &lock);
		fclose(fp);
		fclose(out_fp);
		return 1;
	}

	continued = 0;
	snprintf(username, sizeof username, "%s:", pw->pw_name);
	rewind(fp);
	while (!feof(fp)) {
		fgets(buffer, sizeof buffer, fp);
		if (!continued) { /* Check to see if we're updating this line.  */
			if (strncmp(username, buffer, strlen(username)) == 0) {
				/* we have a match. */
				pw_rest = strchr(buffer, ':');
				*pw_rest++ = '\0';
				pw_rest = strchr(pw_rest, ':');
				fprintf(out_fp, "%s:%s%s", buffer, crypt_pw, pw_rest);
			} else {
				fputs(buffer, out_fp);
			}
		} else {
			fputs(buffer, out_fp);
		}
		if (buffer[strlen(buffer) - 1] == '\n') {
			continued = 0;
		} else {
			continued = 1;
		}
		memset(buffer, 0, sizeof buffer);
	}

	if (fflush(out_fp) || fsync(fileno(out_fp)) || fclose(out_fp)) {
		unlink(buf);
		fcntl(fileno(fp), F_SETLK, &lock);
		fclose(fp);
		return 1;
	}
	if (rename(buf, filename) < 0) {
		fcntl(fileno(fp), F_SETLK, &lock);
		fclose(fp);
		return 1;
	} else {
		fcntl(fileno(fp), F_SETLK, &lock);
		fclose(fp);
		return 0;
	}
}


int passwd_main(int argc, char **argv)
{
	int amroot;
	char *cp;
	char *np;
	char *name;
	char *myname;
	int flag;
	int algo = 1;				/* -a - password algorithm */
	int lflg = 0;				/* -l - lock account */
	int uflg = 0;				/* -u - unlock account */
	int dflg = 0;				/* -d - delete password */
	const struct passwd *pw;

	amroot = (getuid() == 0);
	openlog("passwd", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
	while ((flag = getopt(argc, argv, "a:dlu")) != EOF) {
		switch (flag) {
		case 'a':
			algo = get_algo(optarg);
			break;
		case 'd':
			dflg++;
			break;
		case 'l':
			lflg++;
			break;
		case 'u':
			uflg++;
			break;
		default:
			bb_show_usage();
		}
	}
	myname = (char *) xstrdup(bb_getpwuid(NULL, getuid(), -1));
	/* exits on error */
	if (optind < argc) {
		name = argv[optind];
	} else {
		name = myname;
	}
	if ((lflg || uflg || dflg) && (optind >= argc || !amroot)) {
		bb_show_usage();
	}
	pw = getpwnam(name);
	if (!pw) {
		bb_error_msg_and_die("Unknown user %s", name);
	}
	if (!amroot && pw->pw_uid != getuid()) {
		syslog(LOG_WARNING, "can't change pwd for `%s'", name);
		bb_error_msg_and_die("Permission denied.");
	}
	if (ENABLE_FEATURE_SHADOWPASSWDS) {
		struct spwd *sp = getspnam(name);
		if (!sp) bb_error_msg_and_die("Unknown user %s", name);
		cp = sp->sp_pwdp;
	} else cp = pw->pw_passwd;

	np = name;
	safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
	if (!(dflg || lflg || uflg)) {
		if (!amroot) {
			if (cp[0] == '!') {
				syslog(LOG_WARNING, "password locked for `%s'", np);
				bb_error_msg_and_die( "The password for `%s' cannot be changed.", np);
			}
		}
		printf("Changing password for %s\n", name);
		if (new_password(pw, amroot, algo)) {
			bb_error_msg_and_die( "The password for %s is unchanged.", name);
		}
	} else if (lflg) {
		if (crypt_passwd[0] != '!') {
			memmove(&crypt_passwd[1], crypt_passwd,
					sizeof crypt_passwd - 1);
			crypt_passwd[sizeof crypt_passwd - 1] = '\0';
			crypt_passwd[0] = '!';
		}
	} else if (uflg) {
		if (crypt_passwd[0] == '!') {
			memmove(crypt_passwd, &crypt_passwd[1],
					sizeof crypt_passwd - 1);
		}
	} else if (dflg) {
		crypt_passwd[0] = '\0';
	}
	set_filesize_limit(30000);
	signal(SIGHUP, SIG_IGN);
	signal(SIGINT, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	umask(077);
	xsetuid(0);
	if (!update_passwd(pw, crypt_passwd)) {
		syslog(LOG_INFO, "password for `%s' changed by user `%s'", name,
			   myname);
		printf("Password changed.\n");
	} else {
		syslog(LOG_WARNING, "an error occurred updating the password file");
		bb_error_msg_and_die("An error occurred updating the password file.");
	}
	if (ENABLE_FEATURE_CLEAN_UP) free(myname);
	return (0);
}



static int create_backup(const char *backup, FILE * fp)
{
	struct stat sb;
	struct utimbuf ub;
	FILE *bkfp;
	int c, mask;

	if (fstat(fileno(fp), &sb))
		/* return -1; */
		return 1;

	mask = umask(077);
	bkfp = fopen(backup, "w");
	umask(mask);
	if (!bkfp)
		/* return -1; */
		return 1;

	/* TODO: faster copy, not one-char-at-a-time.  --marekm */
	rewind(fp);
	while ((c = getc(fp)) != EOF) {
		if (putc(c, bkfp) == EOF)
			break;
	}
	if (c != EOF || fflush(bkfp)) {
		fclose(bkfp);
		/* return -1; */
		return 1;
	}
	if (fclose(bkfp))
		/* return -1; */
		return 1;

	ub.actime = sb.st_atime;
	ub.modtime = sb.st_mtime;
	utime(backup, &ub);
	return 0;
}

static int i64c(int i)
{
	if (i <= 0)
		return ('.');
	if (i == 1)
		return ('/');
	if (i >= 2 && i < 12)
		return ('0' - 2 + i);
	if (i >= 12 && i < 38)
		return ('A' - 12 + i);
	if (i >= 38 && i < 63)
		return ('a' - 38 + i);
	return ('z');
}

static char *crypt_make_salt(void)
{
	time_t now;
	static unsigned long x;
	static char result[3];

	time(&now);
	x += now + getpid() + clock();
	result[0] = i64c(((x >> 18) ^ (x >> 6)) & 077);
	result[1] = i64c(((x >> 12) ^ x) & 077);
	result[2] = '\0';
	return result;
}


static int new_password(const struct passwd *pw, int amroot, int algo)
{
	char *clear;
	char *cipher;
	char *cp;
	char salt[12]; /* "$N$XXXXXXXX" or "XX" */
	char orig[200];
	char pass[200];

	if (!amroot && crypt_passwd[0]) {
		if (!(clear = bb_askpass(0, "Old password:"))) {
			/* return -1; */
			return 1;
		}
		cipher = pw_encrypt(clear, crypt_passwd);
		if (strcmp(cipher, crypt_passwd) != 0) {
			syslog(LOG_WARNING, "incorrect password for `%s'",
				   pw->pw_name);
			bb_do_delay(FAIL_DELAY);
			fprintf(stderr, "Incorrect password.\n");
			/* return -1; */
			return 1;
		}
		safe_strncpy(orig, clear, sizeof(orig));
		memset(clear, 0, strlen(clear));
		memset(cipher, 0, strlen(cipher));
	} else {
		orig[0] = '\0';
	}
	if (! (cp=bb_askpass(0, "Enter the new password (minimum of 5, maximum of 8 characters)\n"
					  "Please use a combination of upper and lower case letters and numbers.\n"
					  "Enter new password: ")))
	{
		memset(orig, 0, sizeof orig);
		/* return -1; */
		return 1;
	}
	safe_strncpy(pass, cp, sizeof(pass));
	memset(cp, 0, strlen(cp));
	/* if (!obscure(orig, pass, pw)) { */
	if (obscure(orig, pass, pw)) {
		if (amroot) {
			printf("\nWarning: weak password (continuing).\n");
		} else {
			/* return -1; */
			return 1;
		}
	}
	if (!(cp = bb_askpass(0, "Re-enter new password: "))) {
		memset(orig, 0, sizeof orig);
		/* return -1; */
		return 1;
	}
	if (strcmp(cp, pass)) {
		fprintf(stderr, "Passwords do not match.\n");
		/* return -1; */
		return 1;
	}
	memset(cp, 0, strlen(cp));
	memset(orig, 0, sizeof(orig));
	memset(salt, 0, sizeof(salt));

	if (algo == 1) {
		strcpy(salt, "$1$");
		strcat(salt, crypt_make_salt());
		strcat(salt, crypt_make_salt());
		strcat(salt, crypt_make_salt());
	}

	strcat(salt, crypt_make_salt());
	cp = pw_encrypt(pass, salt);

	memset(pass, 0, sizeof pass);
	safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
	return 0;
}

static void set_filesize_limit(int blocks)
{
	struct rlimit rlimit_fsize;

	rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * blocks;
	setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
}