summaryrefslogtreecommitdiffstats
path: root/login-utils/chfn.c
blob: 752d59821f2a577c855f86b00cea64fcf6d6d108 (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
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
/*
 *   chfn.c -- change your finger information
 *   (c) 1994 by salvatore valente <svalente@athena.mit.edu>
 *   (c) 2012 by Cody Maloney <cmaloney@theoreticalchaos.com>
 *
 *   this program is free software.  you can redistribute it and
 *   modify it under the terms of the gnu general public license.
 *   there is no warranty.
 *
 *   $Author: aebr $
 *   $Revision: 1.18 $
 *   $Date: 1998/06/11 22:30:11 $
 *
 * Updated Thu Oct 12 09:19:26 1995 by faith@cs.unc.edu with security
 * patches from Zefram <A.Main@dcs.warwick.ac.uk>
 *
 * Hacked by Peter Breitenlohner, peb@mppmu.mpg.de,
 * to remove trailing empty fields.  Oct 5, 96.
 *
 *  1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
 *  - added Native Language Support
 */

#include <ctype.h>
#include <errno.h>
#include <getopt.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

#include "c.h"
#include "env.h"
#include "closestream.h"
#include "islocal.h"
#include "nls.h"
#include "setpwnam.h"
#include "strutils.h"
#include "xalloc.h"
#include "logindefs.h"

#include "ch-common.h"

#ifdef HAVE_LIBSELINUX
# include <selinux/selinux.h>
# include "selinux-utils.h"
#endif

#ifdef HAVE_LIBUSER
# include <libuser/user.h>
# include "libuser.h"
#elif CHFN_CHSH_PASSWORD
# include "auth.h"
#endif

struct finfo {
	char *full_name;
	char *office;
	char *office_phone;
	char *home_phone;
	char *other;
};

struct chfn_control {
	struct passwd *pw;
	char *username;
	/*  "oldf"  Contains the users original finger information.
	 *  "newf"  Contains the changed finger information, and contains
	 *          NULL in fields that haven't been changed.
	 *  In the end, "newf" is folded into "oldf".  */
	struct finfo oldf, newf;
	unsigned int
		allow_fullname:1,	/* The login.defs restriction */
		allow_room:1,		   /* see: man login.defs(5) */
		allow_work:1,		   /* and look for CHFN_RESTRICT */
		allow_home:1,		   /* keyword for these four. */
		changed:1,		/* is change requested */
		interactive:1;		/* whether to prompt for fields or not */
};

/* we do not accept gecos field sizes longer than MAX_FIELD_SIZE */
#define MAX_FIELD_SIZE		256

static void __attribute__((__noreturn__)) usage(void)
{
	FILE *fp = stdout;
	fputs(USAGE_HEADER, fp);
	fprintf(fp, _(" %s [options] [<username>]\n"), program_invocation_short_name);

	fputs(USAGE_SEPARATOR, fp);
	fputs(_("Change your finger information.\n"), fp);

	fputs(USAGE_OPTIONS, fp);
	fputs(_(" -f, --full-name <full-name>  real name\n"), fp);
	fputs(_(" -o, --office <office>        office number\n"), fp);
	fputs(_(" -p, --office-phone <phone>   office phone number\n"), fp);
	fputs(_(" -h, --home-phone <phone>     home phone number\n"), fp);
	fputs(USAGE_SEPARATOR, fp);
	printf( " -u, --help                   %s\n", USAGE_OPTSTR_HELP);
	printf( " -V, --version                %s\n", USAGE_OPTSTR_VERSION);
	printf(USAGE_MAN_TAIL("chfn(1)"));
	exit(EXIT_SUCCESS);
}

/*
 *  check_gecos_string () --
 *	check that the given gecos string is legal.  if it's not legal,
 *	output "msg" followed by a description of the problem, and return (-1).
 */
static int check_gecos_string(const char *msg, char *gecos)
{
	const size_t len = strlen(gecos);

	if (MAX_FIELD_SIZE < len) {
		warnx(_("field %s is too long"), msg);
		return -1;
	}
	if (illegal_passwd_chars(gecos)) {
		warnx(_("%s: has illegal characters"), gecos);
		return -1;
	}
	return 0;
}

/*
 *  parse_argv () --
 *	parse the command line arguments.
 *	returns true if no information beyond the username was given.
 */
static void parse_argv(struct chfn_control *ctl, int argc, char **argv)
{
	int index, c, status = 0;
	static const struct option long_options[] = {
		{ "full-name",    required_argument, NULL, 'f' },
		{ "office",       required_argument, NULL, 'o' },
		{ "office-phone", required_argument, NULL, 'p' },
		{ "home-phone",   required_argument, NULL, 'h' },
		{ "help",         no_argument,       NULL, 'u' },
		{ "version",      no_argument,       NULL, 'V' },
		{ NULL, 0, NULL, 0 },
	};

	while ((c = getopt_long(argc, argv, "f:r:p:h:o:uvV", long_options,
				&index)) != -1) {
		switch (c) {
		case 'f':
			if (!ctl->allow_fullname)
				errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Name"));
			ctl->newf.full_name = optarg;
			status += check_gecos_string(_("Name"), optarg);
			break;
		case 'o':
			if (!ctl->allow_room)
				errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office"));
			ctl->newf.office = optarg;
			status += check_gecos_string(_("Office"), optarg);
			break;
		case 'p':
			if (!ctl->allow_work)
				errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office Phone"));
			ctl->newf.office_phone = optarg;
			status += check_gecos_string(_("Office Phone"), optarg);
			break;
		case 'h':
			if (!ctl->allow_home)
				errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Home Phone"));
			ctl->newf.home_phone = optarg;
			status += check_gecos_string(_("Home Phone"), optarg);
			break;
		case 'v': /* deprecated */
		case 'V':
			print_version(EXIT_SUCCESS);
		case 'u':
			usage();
		default:
			errtryhelp(EXIT_FAILURE);
		}
		ctl->changed = 1;
		ctl->interactive = 0;
	}
	if (status != 0)
		exit(EXIT_FAILURE);
	/* done parsing arguments.  check for a username. */
	if (optind < argc) {
		if (optind + 1 < argc) {
			warnx(_("cannot handle multiple usernames"));
			errtryhelp(EXIT_FAILURE);
		}
		ctl->username = argv[optind];
	}
}

/*
 *  parse_passwd () --
 *	take a struct password and fill in the fields of the struct finfo.
 */
static void parse_passwd(struct chfn_control *ctl)
{
	char *gecos;

	if (!ctl->pw)
		return;
	/* use pw_gecos - we take a copy since PAM destroys the original */
	gecos = xstrdup(ctl->pw->pw_gecos);
	/* extract known fields */
	ctl->oldf.full_name = strsep(&gecos, ",");
	ctl->oldf.office = strsep(&gecos, ",");
	ctl->oldf.office_phone = strsep(&gecos, ",");
	ctl->oldf.home_phone = strsep(&gecos, ",");
	/*  extra fields contain site-specific information, and can
	 *  not be changed by this version of chfn.  */
	ctl->oldf.other = strsep(&gecos, ",");
}

/*
 *  ask_new_field () --
 *	ask the user for a given field and check that the string is legal.
 */
static char *ask_new_field(struct chfn_control *ctl, const char *question,
			   char *def_val)
{
	int len;
	char *buf = NULL; /* leave initialized to NULL or getline segfaults */
	size_t dummy = 0;

	if (!def_val)
		def_val = "";

	while (true) {
		printf("%s [%s]:", question, def_val);
		__fpurge(stdin);

		putchar(' ');
		fflush(stdout);

		if (getline(&buf, &dummy, stdin) < 0)
			errx(EXIT_FAILURE, _("Aborted."));

		/* remove white spaces from string end */
		ltrim_whitespace((unsigned char *) buf);
		len = rtrim_whitespace((unsigned char *) buf);
		if (len == 0) {
			free(buf);
			return xstrdup(def_val);
		}
		if (!strcasecmp(buf, "none")) {
			free(buf);
			ctl->changed = 1;
			return xstrdup("");
		}
		if (check_gecos_string(question, buf) >= 0)
			break;
	}
	ctl->changed = 1;
	return buf;
}

/*
 *  get_login_defs()
 *	find /etc/login.defs CHFN_RESTRICT and save restrictions to run time
 */
static void get_login_defs(struct chfn_control *ctl)
{
	const char *s;
	size_t i;
	int broken = 0;

	/* real root does not have restrictions */
	if (geteuid() == getuid() && getuid() == 0) {
		ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
		return;
	}
	s = getlogindefs_str("CHFN_RESTRICT", "");
	if (!strcmp(s, "yes")) {
		ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
		return;
	}
	if (!strcmp(s, "no")) {
		ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
		return;
	}
	for (i = 0; s[i]; i++) {
		switch (s[i]) {
		case 'f':
			ctl->allow_fullname = 1;
			break;
		case 'r':
			ctl->allow_room = 1;
			break;
		case 'w':
			ctl->allow_work = 1;
			break;
		case 'h':
			ctl->allow_home = 1;
			break;
		default:
			broken = 1;
		}
	}
	if (broken)
		warnx(_("%s: CHFN_RESTRICT has unexpected value: %s"), _PATH_LOGINDEFS, s);
	if (!ctl->allow_fullname && !ctl->allow_room && !ctl->allow_work && !ctl->allow_home)
		errx(EXIT_FAILURE, _("%s: CHFN_RESTRICT does not allow any changes"), _PATH_LOGINDEFS);
}

/*
 *  ask_info () --
 *	prompt the user for the finger information and store it.
 */
static void ask_info(struct chfn_control *ctl)
{
	if (ctl->allow_fullname)
		ctl->newf.full_name = ask_new_field(ctl, _("Name"), ctl->oldf.full_name);
	if (ctl->allow_room)
		ctl->newf.office = ask_new_field(ctl, _("Office"), ctl->oldf.office);
	if (ctl->allow_work)
		ctl->newf.office_phone = ask_new_field(ctl, _("Office Phone"), ctl->oldf.office_phone);
	if (ctl->allow_home)
		ctl->newf.home_phone = ask_new_field(ctl, _("Home Phone"), ctl->oldf.home_phone);
	putchar('\n');
}

/*
 *  find_field () --
 *	find field value in uninteractive mode; can be new, old, or blank
 */
static char *find_field(char *nf, char *of)
{
	if (nf)
		return nf;
	if (of)
		return of;
	return xstrdup("");
}

/*
 *  add_missing () --
 *	add not supplied field values when in uninteractive mode
 */
static void add_missing(struct chfn_control *ctl)
{
	ctl->newf.full_name = find_field(ctl->newf.full_name, ctl->oldf.full_name);
	ctl->newf.office = find_field(ctl->newf.office, ctl->oldf.office);
	ctl->newf.office_phone = find_field(ctl->newf.office_phone, ctl->oldf.office_phone);
	ctl->newf.home_phone = find_field(ctl->newf.home_phone, ctl->oldf.home_phone);
	ctl->newf.other = find_field(ctl->newf.other, ctl->oldf.other);
	printf("\n");
}

/*
 *  save_new_data () --
 *	save the given finger info in /etc/passwd.
 *	return zero on success.
 */
static int save_new_data(struct chfn_control *ctl)
{
	char *gecos;
	int len;

	/* create the new gecos string */
	len = xasprintf(&gecos, "%s,%s,%s,%s,%s",
			ctl->newf.full_name,
			ctl->newf.office,
			ctl->newf.office_phone,
			ctl->newf.home_phone,
			ctl->newf.other);

	/* remove trailing empty fields (but not subfields of ctl->newf.other) */
	if (!ctl->newf.other || !*ctl->newf.other) {
		while (len > 0 && gecos[len - 1] == ',')
			len--;
		gecos[len] = 0;
	}

#ifdef HAVE_LIBUSER
	if (set_value_libuser("chfn", ctl->username, ctl->pw->pw_uid,
			LU_GECOS, gecos) < 0) {
#else /* HAVE_LIBUSER */
	/* write the new struct passwd to the passwd file. */
	ctl->pw->pw_gecos = gecos;
	if (setpwnam(ctl->pw, ".chfn") < 0) {
		warn("setpwnam failed");
#endif
		printf(_
		       ("Finger information *NOT* changed.  Try again later.\n"));
		return -1;
	}
	free(gecos);
	printf(_("Finger information changed.\n"));
	return 0;
}

int main(int argc, char **argv)
{
	uid_t uid;
	struct chfn_control ctl = {
		.interactive = 1
	};

	sanitize_env();
	setlocale(LC_ALL, "");	/* both for messages and for iscntrl() below */
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	close_stdout_atexit();

	uid = getuid();

	/* check /etc/login.defs CHFN_RESTRICT */
	get_login_defs(&ctl);

	parse_argv(&ctl, argc, argv);
	if (!ctl.username) {
		ctl.pw = getpwuid(uid);
		if (!ctl.pw)
			errx(EXIT_FAILURE, _("you (user %d) don't exist."),
			     uid);
		ctl.username = ctl.pw->pw_name;
	} else {
		ctl.pw = getpwnam(ctl.username);
		if (!ctl.pw)
			errx(EXIT_FAILURE, _("user \"%s\" does not exist."),
			     ctl.username);
	}
	parse_passwd(&ctl);
#ifndef HAVE_LIBUSER
	if (!(is_local(ctl.username)))
		errx(EXIT_FAILURE, _("can only change local entries"));
#endif

#ifdef HAVE_LIBSELINUX
	if (is_selinux_enabled() > 0) {
		char *user_cxt = NULL;

		if (uid == 0 && !ul_selinux_has_access("passwd", "chfn", &user_cxt))
			errx(EXIT_FAILURE,
			     _("%s is not authorized to change "
			       "the finger info of %s"),
			     user_cxt ? : _("Unknown user context"),
			     ctl.username);

		if (ul_setfscreatecon_from_file(_PATH_PASSWD) != 0)
			errx(EXIT_FAILURE,
			     _("can't set default context for %s"), _PATH_PASSWD);
	}
#endif

#ifdef HAVE_LIBUSER
	/* If we're setuid and not really root, disallow the password change. */
	if (geteuid() != getuid() && uid != ctl.pw->pw_uid) {
#else
	if (uid != 0 && uid != ctl.pw->pw_uid) {
#endif
		errno = EACCES;
		err(EXIT_FAILURE, _("running UID doesn't match UID of user we're "
		      "altering, change denied"));
	}

	printf(_("Changing finger information for %s.\n"), ctl.username);

#if !defined(HAVE_LIBUSER) && defined(CHFN_CHSH_PASSWORD)
	if (!auth_pam("chfn", uid, ctl.username)) {
		return EXIT_FAILURE;
	}
#endif

	if (ctl.interactive)
		ask_info(&ctl);

	add_missing(&ctl);

	if (!ctl.changed) {
		printf(_("Finger information not changed.\n"));
		return EXIT_SUCCESS;
	}

	return save_new_data(&ctl) == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
}