Linux debugging

Check our new training course

Linux debugging, tracing, profiling & perf. analysis

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
/*
  setfiles: based on policycoreutils 2.0.19
  policycoreutils was released under GPL 2.
  Port to BusyBox (c) 2007 by Yuichi Nakamura <ynakam@hitachisoft.jp>
*/

#include "libbb.h"
#if ENABLE_FEATURE_SETFILES_CHECK_OPTION
#include <sepol/sepol.h>
#endif

#define MAX_EXCLUDES 50

struct edir {
	char *directory;
	size_t size;
};

struct globals {
	FILE *outfile;
	char *policyfile;
	char *rootpath;
	int rootpathlen;
	unsigned count;
	int excludeCtr;
	int errors;
	int verbose; /* getopt32 uses it, has to be int */
	smallint recurse; /* Recursive descent */
	smallint follow_mounts;
	/* Behavior flags determined based on setfiles vs. restorecon */
	smallint expand_realpath;  /* Expand paths via realpath */
	smallint abort_on_error; /* Abort the file tree walk upon an error */
	int add_assoc; /* Track inode associations for conflict detection */
	int matchpathcon_flags; /* Flags to matchpathcon */
	dev_t dev_id; /* Device id where target file exists */
	int nerr;
	struct edir excludeArray[MAX_EXCLUDES];
};

#define G (*(struct globals*)&bb_common_bufsiz1)
void BUG_setfiles_globals_too_big(void);
#define INIT_G() do { \
	if (sizeof(G) > COMMON_BUFSIZE) \
		BUG_setfiles_globals_too_big(); \
	/* memset(&G, 0, sizeof(G)); - already is */ \
} while (0)
#define outfile            (G.outfile           )
#define policyfile         (G.policyfile        )
#define rootpath           (G.rootpath          )
#define rootpathlen        (G.rootpathlen       )
#define count              (G.count             )
#define excludeCtr         (G.excludeCtr        )
#define errors             (G.errors            )
#define verbose            (G.verbose           )
#define recurse            (G.recurse           )
#define follow_mounts      (G.follow_mounts     )
#define expand_realpath    (G.expand_realpath   )
#define abort_on_error     (G.abort_on_error    )
#define add_assoc          (G.add_assoc         )
#define matchpathcon_flags (G.matchpathcon_flags)
#define dev_id             (G.dev_id            )
#define nerr               (G.nerr              )
#define excludeArray       (G.excludeArray      )

/* Must match getopt32 string! */
enum {
	OPT_d = (1 << 0),
	OPT_e = (1 << 1),
	OPT_f = (1 << 2),
	OPT_i = (1 << 3),
	OPT_l = (1 << 4),
	OPT_n = (1 << 5),
	OPT_p = (1 << 6),
	OPT_q = (1 << 7),
	OPT_r = (1 << 8),
	OPT_s = (1 << 9),
	OPT_v = (1 << 10),
	OPT_o = (1 << 11),
	OPT_F = (1 << 12),
	OPT_W = (1 << 13),
	OPT_c = (1 << 14), /* c only for setfiles */
	OPT_R = (1 << 14), /* R only for restorecon */
};
#define FLAG_d_debug         (option_mask32 & OPT_d)
#define FLAG_e               (option_mask32 & OPT_e)
#define FLAG_f               (option_mask32 & OPT_f)
#define FLAG_i_ignore_enoent (option_mask32 & OPT_i)
#define FLAG_l_take_log      (option_mask32 & OPT_l)
#define FLAG_n_dry_run       (option_mask32 & OPT_n)
#define FLAG_p_progress      (option_mask32 & OPT_p)
#define FLAG_q_quiet         (option_mask32 & OPT_q)
#define FLAG_r               (option_mask32 & OPT_r)
#define FLAG_s               (option_mask32 & OPT_s)
#define FLAG_v               (option_mask32 & OPT_v)
#define FLAG_o               (option_mask32 & OPT_o)
#define FLAG_F_force         (option_mask32 & OPT_F)
#define FLAG_W_warn_no_match (option_mask32 & OPT_W)
#define FLAG_c               (option_mask32 & OPT_c)
#define FLAG_R               (option_mask32 & OPT_R)


static void qprintf(const char *fmt, ...)
{
	/* quiet, do nothing */
}

static void inc_err(void)
{
	nerr++;
	if (nerr > 9 && !FLAG_d_debug) {
		bb_error_msg_and_die("exiting after 10 errors");
	}
}

static void add_exclude(const char *const directory)
{
	struct stat sb;
	size_t len;

	if (directory == NULL || directory[0] != '/') {
		bb_error_msg_and_die("full path required for exclude: %s", directory);

	}
	if (lstat(directory, &sb)) {
		bb_error_msg("directory \"%s\" not found, ignoring", directory);
		return;
	}
	if ((sb.st_mode & S_IFDIR) == 0) {
		bb_error_msg("\"%s\" is not a directory: mode %o, ignoring",
			directory, sb.st_mode);
		return;
	}
	if (excludeCtr == MAX_EXCLUDES) {
		bb_error_msg_and_die("maximum excludes %d exceeded", MAX_EXCLUDES);
	}

	len = strlen(directory);
	while (len > 1 && directory[len - 1] == '/') {
		len--;
	}
	excludeArray[excludeCtr].directory = xstrndup(directory, len);
	excludeArray[excludeCtr++].size = len;
}

static bool exclude(const char *file)
{
	int i = 0;
	for (i = 0; i < excludeCtr; i++) {
		if (strncmp(file, excludeArray[i].directory,
					excludeArray[i].size) == 0) {
			if (file[excludeArray[i].size] == '\0'
			 || file[excludeArray[i].size] == '/') {
				return 1;
			}
		}
	}
	return 0;
}

static int match(const char *name, struct stat *sb, char **con)
{
	int ret;
	char path[PATH_MAX + 1];
	char *tmp_path = xstrdup(name);

	if (excludeCtr > 0 && exclude(name)) {
		goto err;
	}
	ret = lstat(name, sb);
	if (ret) {
		if (FLAG_i_ignore_enoent && errno == ENOENT) {
			free(tmp_path);
			return 0;
		}
		bb_error_msg("stat(%s)", name);
		goto err;
	}

	if (expand_realpath) {
		if (S_ISLNK(sb->st_mode)) {
			char *p = NULL;
			char *file_sep;

			size_t len = 0;

			if (verbose > 1)
				bb_error_msg("warning! %s refers to a symbolic link, not following last component", name);

			file_sep = strrchr(tmp_path, '/');
			if (file_sep == tmp_path) {
				file_sep++;
				path[0] = '\0';
				p = path;
			} else if (file_sep) {
				*file_sep++ = '\0';
				p = realpath(tmp_path, path);
			} else {
				file_sep = tmp_path;
				p = realpath("./", path);
			}
			if (p)
				len = strlen(p);
			if (!p || len + strlen(file_sep) + 2 > PATH_MAX) {
				bb_perror_msg("realpath(%s) failed", name);
				goto err;
			}
			p += len;
			/* ensure trailing slash of directory name */
			if (len == 0 || p[-1] != '/') {
				*p++ = '/';
			}
			strcpy(p, file_sep);
			name = path;
			if (excludeCtr > 0 && exclude(name))
				goto err;

		} else {
			char *p;
			p = realpath(name, path);
			if (!p) {
				bb_perror_msg("realpath(%s)", name);
				goto err;
			}
			name = p;
			if (excludeCtr > 0 && exclude(name))
				goto err;
		}
	}

	/* name will be what is matched in the policy */
	if (NULL != rootpath) {
		if (0 != strncmp(rootpath, name, rootpathlen)) {
			bb_error_msg("%s is not located in %s",
				name, rootpath);
			goto err;
		}
		name += rootpathlen;
	}

	free(tmp_path);
	if (rootpath != NULL && name[0] == '\0')
		/* this is actually the root dir of the alt root */
		return matchpathcon_index("/", sb->st_mode, con);
	return matchpathcon_index(name, sb->st_mode, con);
 err:
	free(tmp_path);
	return -1;
}

/* Compare two contexts to see if their differences are "significant",
 * or whether the only difference is in the user. */
static bool only_changed_user(const char *a, const char *b)
{
	if (FLAG_F_force)
		return 0;
	if (!a || !b)
		return 0;
	a = strchr(a, ':'); /* Rest of the context after the user */
	b = strchr(b, ':');
	if (!a || !b)
		return 0;
	return (strcmp(a, b) == 0);
}

static int restore(const char *file)
{
	char *my_file;
	struct stat my_sb;
	int i, j, ret;
	char *context = NULL;
	char *newcon = NULL;
	bool user_only_changed = 0;
	int retval = 0;

	my_file = bb_simplify_path(file);

	i = match(my_file, &my_sb, &newcon);

	if (i < 0) /* No matching specification. */
		goto out;

	if (FLAG_p_progress) {
		count++;
		if (count % 0x400 == 0) { /* every 1024 times */
			count = (count % (80*0x400));
			if (count == 0)
				bb_putchar('\n');
			bb_putchar('*');
			fflush(stdout);
		}
	}

	/*
	 * Try to add an association between this inode and
	 * this specification. If there is already an association
	 * for this inode and it conflicts with this specification,
	 * then use the last matching specification.
	 */
	if (add_assoc) {
		j = matchpathcon_filespec_add(my_sb.st_ino, i, my_file);
		if (j < 0)
			goto err;

		if (j != i) {
			/* There was already an association and it took precedence. */
			goto out;
		}
	}

	if (FLAG_d_debug)
		printf("%s: %s matched by %s\n", applet_name, my_file, newcon);

	/* Get the current context of the file. */
	ret = lgetfilecon_raw(my_file, &context);
	if (ret < 0) {
		if (errno == ENODATA) {
			context = NULL; /* paranoia */
		} else {
			bb_perror_msg("lgetfilecon_raw on %s", my_file);
			goto err;
		}
		user_only_changed = 0;
	} else
		user_only_changed = only_changed_user(context, newcon);

	/*
	 * Do not relabel the file if the matching specification is
	 * <<none>> or the file is already labeled according to the
	 * specification.
	 */
	if ((strcmp(newcon, "<<none>>") == 0)
	 || (context && (strcmp(context, newcon) == 0) && !FLAG_F_force)) {
		goto out;
	}

	if (!FLAG_F_force && context && (is_context_customizable(context) > 0)) {
		if (verbose > 1) {
			bb_error_msg("skipping %s. %s is customizable_types",
				my_file, context);
		}
		goto out;
	}

	if (verbose) {
		/* If we're just doing "-v", trim out any relabels where
		 * the user has changed but the role and type are the
		 * same.  For "-vv", emit everything. */
		if (verbose > 1 || !user_only_changed) {
			bb_info_msg("%s: reset %s context %s->%s",
				applet_name, my_file, context ?: "", newcon);
		}
	}

	if (FLAG_l_take_log && !user_only_changed) {
		if (context)
			bb_info_msg("relabeling %s from %s to %s", my_file, context, newcon);
		else
			bb_info_msg("labeling %s to %s", my_file, newcon);
	}

	if (outfile && !user_only_changed)
		fprintf(outfile, "%s\n", my_file);

	/*
	 * Do not relabel the file if -n was used.
	 */
	if (FLAG_n_dry_run || user_only_changed)
		goto out;

	/*
	 * Relabel the file to the specified context.
	 */
	ret = lsetfilecon(my_file, newcon);
	if (ret) {
		bb_perror_msg("lsetfileconon(%s,%s)", my_file, newcon);
		goto err;
	}

 out:
	freecon(context);
	freecon(newcon);
	free(my_file);
	return retval;
 err:
	retval--; /* -1 */
	goto out;
}

/*
 * Apply the last matching specification to a file.
 * This function is called by recursive_action on each file during
 * the directory traversal.
 */
static int apply_spec(const char *file,
		      struct stat *sb, void *userData, int depth)
{
	if (!follow_mounts) {
		/* setfiles does not process across different mount points */
		if (sb->st_dev != dev_id) {
			return SKIP;
		}
	}
	errors |= restore(file);
	if (abort_on_error && errors)
		return FALSE;
	return TRUE;
}


static int canoncon(const char *path, unsigned lineno, char **contextp)
{
	static const char err_msg[] ALIGN1 = "%s: line %u has invalid context %s";

	char *tmpcon;
	char *context = *contextp;
	int invalid = 0;

#if ENABLE_FEATURE_SETFILES_CHECK_OPTION
	if (policyfile) {
		if (sepol_check_context(context) >= 0)
			return 0;
		/* Exit immediately if we're in checking mode. */
		bb_error_msg_and_die(err_msg, path, lineno, context);
	}
#endif

	if (security_canonicalize_context_raw(context, &tmpcon) < 0) {
		if (errno != ENOENT) {
			invalid = 1;
			inc_err();
		}
	} else {
		free(context);
		*contextp = tmpcon;
	}

	if (invalid) {
		bb_error_msg(err_msg, path, lineno, context);
	}

	return invalid;
}

static int process_one(char *name)
{
	struct stat sb;
	int rc;

	rc = lstat(name, &sb);
	if (rc < 0) {
		if (FLAG_i_ignore_enoent && errno == ENOENT)
			return 0;
		bb_perror_msg("stat(%s)", name);
		goto err;
	}
	dev_id = sb.st_dev;

	if (S_ISDIR(sb.st_mode) && recurse) {
		if (recursive_action(name,
				     ACTION_RECURSE,
				     apply_spec,
				     apply_spec,
				     NULL, 0) != TRUE) {
			bb_error_msg("error while labeling %s", name);
			goto err;
		}
	} else {
		rc = restore(name);
		if (rc)
			goto err;
	}

 out:
	if (add_assoc) {
		if (FLAG_q_quiet)
			set_matchpathcon_printf(&qprintf);
		matchpathcon_filespec_eval();
		set_matchpathcon_printf(NULL);
		matchpathcon_filespec_destroy();
	}

	return rc;

 err:
	rc = -1;
	goto out;
}

int setfiles_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int setfiles_main(int argc, char **argv)
{
	struct stat sb;
	int rc, i = 0;
	const char *input_filename = NULL;
	char *buf = NULL;
	size_t buf_len;
	int flags;
	llist_t *exclude_dir = NULL;
	char *out_filename = NULL;

	INIT_G();

	if (applet_name[0] == 's') { /* "setfiles" */
		/*
		 * setfiles:
		 * Recursive descent,
		 * Does not expand paths via realpath,
		 * Aborts on errors during the file tree walk,
		 * Try to track inode associations for conflict detection,
		 * Does not follow mounts,
		 * Validates all file contexts at init time.
		 */
		recurse = 1;
		abort_on_error = 1;
		add_assoc = 1;
		/* follow_mounts = 0; - already is */
		matchpathcon_flags = MATCHPATHCON_VALIDATE | MATCHPATHCON_NOTRANS;
	} else {
		/*
		 * restorecon:
		 * No recursive descent unless -r/-R,
		 * Expands paths via realpath,
		 * Do not abort on errors during the file tree walk,
		 * Do not try to track inode associations for conflict detection,
		 * Follows mounts,
		 * Does lazy validation of contexts upon use.
		 */
		expand_realpath = 1;
		follow_mounts = 1;
		matchpathcon_flags = MATCHPATHCON_NOTRANS;
		/* restorecon only */
		selinux_or_die();
	}

	set_matchpathcon_flags(matchpathcon_flags);

	opt_complementary = "e::vv:v--p:p--v:v--q:q--v";
	/* Option order must match OPT_x definitions! */
	if (applet_name[0] == 'r') { /* restorecon */
		flags = getopt32(argv, "de:f:ilnpqrsvo:FWR",
			&exclude_dir, &input_filename, &out_filename, &verbose);
	} else { /* setfiles */
		flags = getopt32(argv, "de:f:ilnpqr:svo:FW"
				USE_FEATURE_SETFILES_CHECK_OPTION("c:"),
			&exclude_dir, &input_filename, &rootpath, &out_filename,
				 USE_FEATURE_SETFILES_CHECK_OPTION(&policyfile,)
			&verbose);
	}

#if ENABLE_FEATURE_SETFILES_CHECK_OPTION
	if ((applet_name[0] == 's') && (flags & OPT_c)) {
		FILE *policystream;

		policystream = xfopen(policyfile, "r");
		if (sepol_set_policydb_from_file(policystream) < 0) {
			bb_error_msg_and_die("sepol_set_policydb_from_file on %s", policyfile);
		}
		fclose(policystream);

		/* Only process the specified file_contexts file, not
		   any .homedirs or .local files, and do not perform
		   context translations. */
		set_matchpathcon_flags(MATCHPATHCON_BASEONLY |
				       MATCHPATHCON_NOTRANS |
				       MATCHPATHCON_VALIDATE);
	}
#endif

	while (exclude_dir)
		add_exclude(llist_pop(&exclude_dir));

	if (flags & OPT_o) {
		outfile = stdout;
		if (NOT_LONE_CHAR(out_filename, '-')) {
			outfile = xfopen(out_filename, "w");
		}
	}
	if (applet_name[0] == 'r') { /* restorecon */
		if (flags & (OPT_r | OPT_R))
			recurse = 1;
	} else { /* setfiles */
		if (flags & OPT_r)
			rootpathlen = strlen(rootpath);
	}
	if (flags & OPT_s) {
		input_filename = "-";
		add_assoc = 0;
	}

	if (applet_name[0] == 's') { /* setfiles */
		/* Use our own invalid context checking function so that
		   we can support either checking against the active policy or
		   checking against a binary policy file. */
		set_matchpathcon_canoncon(&canoncon);
		if (argc == 1)
			bb_show_usage();
		if (stat(argv[optind], &sb) < 0) {
			bb_simple_perror_msg_and_die(argv[optind]);
		}
		if (!S_ISREG(sb.st_mode)) {
			bb_error_msg_and_die("spec file %s is not a regular file", argv[optind]);
		}
		/* Load the file contexts configuration and check it. */
		rc = matchpathcon_init(argv[optind]);
		if (rc < 0) {
			bb_simple_perror_msg_and_die(argv[optind]);
		}

		optind++;

		if (nerr)
			exit(1);
	}

	if (input_filename) {
		ssize_t len;
		FILE *f = stdin;

		if (NOT_LONE_CHAR(input_filename, '-'))
			f = xfopen(input_filename, "r");
		while ((len = getline(&buf, &buf_len, f)) > 0) {
			buf[len - 1] = '\0';
			errors |= process_one(buf);
		}
		if (ENABLE_FEATURE_CLEAN_UP)
			fclose_if_not_stdin(f);
	} else {
		if (optind >= argc)
			bb_show_usage();
		for (i = optind; i < argc; i++) {
			errors |= process_one(argv[i]);
		}
	}

	if (FLAG_W_warn_no_match)
		matchpathcon_checkmatches(argv[0]);

	if (ENABLE_FEATURE_CLEAN_UP && outfile)
		fclose(outfile);

	return errors;
}