summaryrefslogtreecommitdiffstats
path: root/libmisc/limits.c
blob: f40e17161a951951e49e272d00b2373a437b5188 (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
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
/*
 * Copyright (c) 1989 - 1994, Julianne Frances Haugh
 * Copyright (c) 1996 - 1999, Marek Michałkiewicz
 * Copyright (c) 2003 - 2006, Tomasz Kłoczko
 * Copyright (c) 2007 - 2010, Nicolas François
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the copyright holders or contributors may not be used to
 *    endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Separated from setup.c.  --marekm
 * Resource limits thanks to Cristian Gafton.
 * Enhancements of resource limit code by Thomas Orgis <thomas@orgis.org>
 */

#include <config.h>

#ifndef USE_PAM

#ident "$Id$"

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <ctype.h>
#include "prototypes.h"
#include "defines.h"
#include <pwd.h>
#include "getdef.h"
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#define LIMITS
#endif
#ifdef LIMITS
#ifndef LIMITS_FILE
#define LIMITS_FILE "/etc/limits"
#endif
#define LOGIN_ERROR_RLIMIT	1
#define LOGIN_ERROR_LOGIN	2
/* Set a limit on a resource */
/*
 *	rlimit - RLIMIT_XXXX
 *	value - string value to be read
 *	multiplier - value*multiplier is the actual limit
 */
static int setrlimit_value (unsigned int resource,
                            const char *value,
                            unsigned int multiplier)
{
	struct rlimit rlim;
	rlim_t limit;

	/* The "-" is special, not belonging to a strange negative limit.
	 * It is infinity, in a controlled way.
	 */
	if ('-' == value[0]) {
		limit = RLIM_INFINITY;
	}
	else {
		/* We cannot use getlong here because it fails when there
		 * is more to the value than just this number!
		 * Also, we are limited to base 10 here (hex numbers will not
		 * work with the limit string parser as is anyway)
		 */
		char *endptr;
		long longlimit = strtol (value, &endptr, 10);
		if ((0 == longlimit) && (value == endptr)) {
			/* No argument at all. No-op.
			 * FIXME: We could instead throw an error, though.
			 */
			return 0;
		}
		longlimit *= multiplier;
		limit = (rlim_t)longlimit;
		if (longlimit != limit)
		{
			/* FIXME: Again, silent error handling...
			 * Wouldn't screaming make more sense?
			 */
			return 0;
		}
	}

	rlim.rlim_cur = limit;
	rlim.rlim_max = limit;
	if (setrlimit (resource, &rlim) != 0) {
		return LOGIN_ERROR_RLIMIT;
	}
	return 0;
}


static int set_prio (const char *value)
{
	long prio;

	if (   (getlong (value, &prio) == 0)
	    || (prio != (int) prio)) {
		return 0;
	}
	if (setpriority (PRIO_PROCESS, 0, (int) prio) != 0) {
		return LOGIN_ERROR_RLIMIT;
	}
	return 0;
}


static int set_umask (const char *value)
{
	unsigned long int mask;

	if (   (getulong (value, &mask) == 0)
	    || (mask != (mode_t) mask)) {
		return 0;
	}

	(void) umask ((mode_t) mask);
	return 0;
}


/* Counts the number of user logins and check against the limit */
static int check_logins (const char *name, const char *maxlogins)
{
#ifdef USE_UTMPX
	struct utmpx *ut;
#else				/* !USE_UTMPX */
	struct utmp *ut;
#endif				/* !USE_UTMPX */
	unsigned long limit, count;

	if (getulong (maxlogins, &limit) == 0) {
		return 0;
	}

	if (0 == limit) {	/* maximum 0 logins ? */
		SYSLOG ((LOG_WARN, "No logins allowed for `%s'\n", name));
		return LOGIN_ERROR_LOGIN;
	}

	count = 0;
#ifdef USE_UTMPX
	setutxent ();
	while ((ut = getutxent ()))
#else				/* !USE_UTMPX */
	setutent ();
	while ((ut = getutent ()))
#endif				/* !USE_UTMPX */
	{
		if (USER_PROCESS != ut->ut_type) {
			continue;
		}
		if ('\0' == ut->ut_user[0]) {
			continue;
		}
		if (strncmp (name, ut->ut_user, sizeof (ut->ut_user)) != 0) {
			continue;
		}
		count++;
		if (count > limit) {
			break;
		}
	}
#ifdef USE_UTMPX
	endutxent ();
#else				/* !USE_UTMPX */
	endutent ();
#endif				/* !USE_UTMPX */
	/*
	 * This is called after setutmp(), so the number of logins counted
	 * includes the user who is currently trying to log in.
	 */
	if (count > limit) {
		SYSLOG ((LOG_WARN,
		         "Too many logins (max %lu) for %s\n",
		         limit, name));
		return LOGIN_ERROR_LOGIN;
	}
	return 0;
}

/* Function setup_user_limits - checks/set limits for the curent login
 * Original idea from Joel Katz's lshell. Ported to shadow-login
 * by Cristian Gafton - gafton@sorosis.ro
 *
 * We are passed a string of the form ('BASH' constants for ulimit)
 *     [Aa][Cc][Dd][Ff][Mm][Nn][Rr][Ss][Tt][Uu][Ll][Pp][Ii][Oo]
 *     (eg. 'C2F256D2048N5' or 'C2 F256 D2048 N5')
 * where:
 * [Aa]: a = RLIMIT_AS		max address space (KB)
 * [Cc]: c = RLIMIT_CORE	max core file size (KB)
 * [Dd]: d = RLIMIT_DATA	max data size (KB)
 * [Ff]: f = RLIMIT_FSIZE	max file size (KB)
 * [Ii]: i = RLIMIT_NICE    max nice value (0..39 translates to 20..-19)
 * [Kk]: k = file creation masK (umask)
 * [Ll]: l = max number of logins for this user
 * [Mm]: m = RLIMIT_MEMLOCK	max locked-in-memory address space (KB)
 * [Nn]: n = RLIMIT_NOFILE	max number of open files
 * [Oo]: o = RLIMIT_RTPRIO  max real time priority (linux/sched.h 0..MAX_RT_PRIO)
 * [Pp]: p = process priority -20..20 (negative = high, positive = low)
 * [Rr]: r = RLIMIT_RSS		max resident set size (KB)
 * [Ss]: s = RLIMIT_STACK	max stack size (KB)
 * [Tt]: t = RLIMIT_CPU		max CPU time (MIN)
 * [Uu]: u = RLIMIT_NPROC	max number of processes
 *
 * NOTE: Remember to extend the "no-limits" string below when adding a new
 * limit...
 *
 * Return value:
 *		0 = okay, of course
 *		LOGIN_ERROR_RLIMIT = error setting some RLIMIT
 *		LOGIN_ERROR_LOGIN  = error - too many logins for this user
 *
 * buf - the limits string
 * name - the username
 */
static int do_user_limits (const char *buf, const char *name)
{
	const char *pp;
	int retval = 0;
	bool reported = false;

	pp = buf;
	/* Skip leading whitespace. */
	while ((' ' == *pp) || ('\t' == *pp)) {
		pp++;
	}

	/* The special limit string "-" results in no limit for all known
	 * limits.
	 * We achieve that by parsing a full limit string, parts of it
	 * being ignored if a limit type is not known to the system.
	 * Though, there will be complaining for unknown limit types.
	 */
	if (strcmp (pp, "-") == 0) {
		/* Remember to extend this, too, when adding new limits!
		 * Oh... but "unlimited" does not make sense for umask,
		 * or does it? (K-)
		 */
		pp = "A- C- D- F- I- L- M- N- O- P- R- S- T- U-";
	}

	while ('\0' != *pp) {
		switch (*pp++) {
#ifdef RLIMIT_AS
		case 'a':
		case 'A':
			/* RLIMIT_AS - max address space (KB) */
			retval |= setrlimit_value (RLIMIT_AS, pp, 1024);
			break;
#endif
#ifdef RLIMIT_CORE
		case 'c':
		case 'C':
			/* RLIMIT_CORE - max core file size (KB) */
			retval |= setrlimit_value (RLIMIT_CORE, pp, 1024);
			break;
#endif
#ifdef RLIMIT_DATA
		case 'd':
		case 'D':
			/* RLIMIT_DATA - max data size (KB) */
			retval |= setrlimit_value (RLIMIT_DATA, pp, 1024);
			break;
#endif
#ifdef RLIMIT_FSIZE
		case 'f':
		case 'F':
			/* RLIMIT_FSIZE - Maximum filesize (KB) */
			retval |= setrlimit_value (RLIMIT_FSIZE, pp, 1024);
			break;
#endif
#ifdef RLIMIT_NICE
		case 'i':
		case 'I':
			/* RLIMIT_NICE - max scheduling priority (0..39) */
			retval |= setrlimit_value (RLIMIT_NICE, pp, 1);
			break;
#endif
		case 'k':
		case 'K':
			retval |= set_umask (pp);
			break;
		case 'l':
		case 'L':
			/* LIMIT the number of concurrent logins */
			retval |= check_logins (name, pp);
			break;
#ifdef RLIMIT_MEMLOCK
		case 'm':
		case 'M':
			/* RLIMIT_MEMLOCK - max locked-in-memory address space (KB) */
			retval |= setrlimit_value (RLIMIT_MEMLOCK, pp, 1024);
			break;
#endif
#ifdef RLIMIT_NOFILE
		case 'n':
		case 'N':
			/* RLIMIT_NOFILE - max number of open files */
			retval |= setrlimit_value (RLIMIT_NOFILE, pp, 1);
			break;
#endif
#ifdef RLIMIT_RTPRIO
		case 'o':
		case 'O':
			/* RLIMIT_RTPRIO - max real time priority (0..MAX_RT_PRIO) */
			retval |= setrlimit_value (RLIMIT_RTPRIO, pp, 1);
			break;
#endif
		case 'p':
		case 'P':
			retval |= set_prio (pp);
			break;
#ifdef RLIMIT_RSS
		case 'r':
		case 'R':
			/* RLIMIT_RSS - max resident set size (KB) */
			retval |= setrlimit_value (RLIMIT_RSS, pp, 1024);
			break;
#endif
#ifdef RLIMIT_STACK
		case 's':
		case 'S':
			/* RLIMIT_STACK - max stack size (KB) */
			retval |= setrlimit_value (RLIMIT_STACK, pp, 1024);
			break;
#endif
#ifdef RLIMIT_CPU
		case 't':
		case 'T':
			/* RLIMIT_CPU - max CPU time (MIN) */
			retval |= setrlimit_value (RLIMIT_CPU, pp, 60);
			break;
#endif
#ifdef RLIMIT_NPROC
		case 'u':
		case 'U':
			/* RLIMIT_NPROC - max number of processes */
			retval |= setrlimit_value (RLIMIT_NPROC, pp, 1);
			break;
#endif
		default:
			/* Only report invalid strings once */
			/* Note: A string can be invalid just because a
			 * specific (theoretically valid) setting is not
			 * supported by this build.
			 * It is just a warning in syslog anyway. The line
			 * is still processed
			 */
			if (!reported) {
				SYSLOG ((LOG_WARN,
				         "Invalid limit string: '%s'",
				         pp-1));
				reported = true;
				retval |= LOGIN_ERROR_RLIMIT;
			}
		}
		/* After parsing one limit setting (or just complaining
		 * about it), one still needs to skip its argument to
		 * prevent a bogus warning on trying to parse that as
		 * limit specification.
		 * So, let's skip all digits, "-" and our limited set of
		 * whitespace.
		 */
		while (   isdigit (*pp)
		       || ('-'  == *pp)
		       || (' '  == *pp)
		       || ('\t' ==*pp)) {
			pp++;
		}
	}
	return retval;
}

/* Check if user uname is in the group gname.
 * Can I be sure that gr_mem contains no UID as string?
 * Returns true when user is in the group, false when not.
 * Any error is treated as false.
 */
static bool user_in_group (const char *uname, const char *gname)
{
	struct group *groupdata;

	if (uname == NULL || gname == NULL){ 
		return false;
	}

	/* We are not claiming to be re-entrant!
	 * In case of paranoia or a multithreaded login program,
	 * one needs to add some mess for getgrnam_r. */
	groupdata = getgrnam (gname);
	if (NULL == groupdata) {
		SYSLOG ((LOG_WARN, "Nonexisting group `%s' in limits file.",
		         gname));
		return false;
	}

	return is_on_list (groupdata->gr_mem, uname);
}

static int setup_user_limits (const char *uname)
{
	FILE *fil;
	char buf[1024];
	char name[1024];
	char limits[1024];
	char deflimits[1024];
	char tempbuf[1024];

	/* init things */
	memzero (buf, sizeof (buf));
	memzero (name, sizeof (name));
	memzero (limits, sizeof (limits));
	memzero (deflimits, sizeof (deflimits));
	memzero (tempbuf, sizeof (tempbuf));

	/* start the checks */
	fil = fopen (LIMITS_FILE, "r");
	if (fil == NULL) {
		return 0;
	}
	/* The limits file have the following format:
	 * - '#' (comment) chars only as first chars on a line;
	 * - username must start on first column (or *, or @group)
	 *
	 * FIXME: A better (smarter) checking should be done
	 */
	while (fgets (buf, 1024, fil) != NULL) {
		if (('#' == buf[0]) || ('\n' == buf[0])) {
			continue;
		}
		memzero (tempbuf, sizeof (tempbuf));
		/* a valid line should have a username, then spaces,
		 * then limits
		 * we allow the format:
		 * username    L2  D2048  R4096
		 * where spaces={' ',\t}. Also, we reject invalid limits.
		 * Imposing a limit should be done with care, so a wrong
		 * entry means no care anyway :-).
		 *
		 * A '-' as a limits strings means no limits
		 *
		 * The username can also be:
		 *  '*': the default limits (only the last is taken into
		 *       account)
		 *  @group: the limit applies to the members of the group
		 *
		 * To clarify: The first entry with matching user name rules,
		 * everything after it is ignored. If there is no user entry,
		 * the last encountered entry for a matching group rules.
		 * If there is no matching group entry, the default limits rule.
		 */
		if (sscanf (buf, "%s%[ACDFIKLMNOPRSTUacdfiklmnoprstu0-9 \t-]",
		            name, tempbuf) == 2) {
			if (strcmp (name, uname) == 0) {
				strcpy (limits, tempbuf);
				break;
			} else if (strcmp (name, "*") == 0) {
				strcpy (deflimits, tempbuf);
			} else if (name[0] == '@') {
				/* If the user is in the group, the group
				 * limits apply unless later a line for
				 * the specific user is found.
				 */
				if (user_in_group (uname, name+1)) {
					strcpy (limits, tempbuf);
				}
			}
		}
	}
	(void) fclose (fil);
	if (limits[0] == '\0') {
		/* no user specific limits */
		if (deflimits[0] == '\0') {	/* no default limits */
			return 0;
		}
		strcpy (limits, deflimits);	/* use the default limits */
	}
	return do_user_limits (limits, uname);
}
#endif				/* LIMITS */


static void setup_usergroups (const struct passwd *info)
{
	const struct group *grp;

/*
 *	if not root, and UID == GID, and username is the same as primary
 *	group name, set umask group bits to be the same as owner bits
 *	(examples: 022 -> 002, 077 -> 007).
 */
	if ((0 != info->pw_uid) && (info->pw_uid == info->pw_gid)) {
		/* local, no need for xgetgrgid */
		grp = getgrgid (info->pw_gid);
		if (   (NULL != grp)
		    && (strcmp (info->pw_name, grp->gr_name) == 0)) {
			mode_t tmpmask;
			tmpmask = umask (0777);
			tmpmask = (tmpmask & ~070) | ((tmpmask >> 3) & 070);
			(void) umask (tmpmask);
		}
	}
}

/*
 *	set the process nice, ulimit, and umask from the password file entry
 */

void setup_limits (const struct passwd *info)
{
	char *cp;

	if (getdef_bool ("USERGROUPS_ENAB")) {
		setup_usergroups (info);
	}

	/*
	 * See if the GECOS field contains values for NICE, UMASK or ULIMIT.
	 * If this feature is enabled in /etc/login.defs, we make those
	 * values the defaults for this login session.
	 */

	if (getdef_bool ("QUOTAS_ENAB")) {
#ifdef LIMITS
		if (info->pw_uid != 0) {
			if ((setup_user_limits (info->pw_name) & LOGIN_ERROR_LOGIN) != 0) {
				(void) fputs (_("Too many logins.\n"), stderr);
				(void) sleep (2); /* XXX: Should be FAIL_DELAY */
				exit (EXIT_FAILURE);
			}
		}
#endif
		for (cp = info->pw_gecos; cp != NULL; cp = strchr (cp, ',')) {
			if (',' == *cp) {
				cp++;
			}

			if (strncmp (cp, "pri=", 4) == 0) {
				long int inc;
				if (   (getlong (cp + 4, &inc) == 1)
				    && (inc >= -20) && (inc <= 20)) {
					errno = 0;
					if (   (nice ((int) inc) != -1)
					    || (0 != errno)) {
						continue;
					}
				}

				/* Failed to parse or failed to nice() */
				SYSLOG ((LOG_WARN,
				         "Can't set the nice value for user %s",
				         info->pw_name));

				continue;
			}
			if (strncmp (cp, "ulimit=", 7) == 0) {
				long int blocks;
				if (   (getlong (cp + 7, &blocks) == 0)
				    || (blocks != (int) blocks)
				    || (set_filesize_limit ((int) blocks) != 0)) {
					SYSLOG ((LOG_WARN,
					         "Can't set the ulimit for user %s",
					         info->pw_name));
				}
				continue;
			}
			if (strncmp (cp, "umask=", 6) == 0) {
				unsigned long int mask;
				if (   (getulong (cp + 6, &mask) == 0)
				    || (mask != (mode_t) mask)) {
					SYSLOG ((LOG_WARN,
					         "Can't set umask value for user %s",
					         info->pw_name));
				} else {
					(void) umask ((mode_t) mask);
				}

				continue;
			}
		}
	}
}

#else				/* !USE_PAM */
extern int errno;		/* warning: ANSI C forbids an empty source file */
#endif				/* !USE_PAM */