File: sefcontext_compile.c

package info (click to toggle)
libselinux 2.8-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, experimental, sid
  • size: 2,080 kB
  • sloc: ansic: 16,057; makefile: 379; sh: 23
file content (463 lines) | stat: -rw-r--r-- 11,871 bytes parent folder | download | duplicates (3)
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
#include <ctype.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <getopt.h>
#include <limits.h>
#include <selinux/selinux.h>
#include <sepol/sepol.h>

#include "../src/label_file.h"
#include "../src/regex.h"

const char *policy_file;
static int ctx_err;

static int validate_context(char **ctxp)
{
	char *ctx = *ctxp;

	if (policy_file && sepol_check_context(ctx) < 0) {
		ctx_err = -1;
		return ctx_err;
	}

	return 0;
}

static int process_file(struct selabel_handle *rec, const char *filename)
{
	unsigned int line_num;
	int rc;
	char *line_buf = NULL;
	size_t line_len = 0;
	FILE *context_file;
	const char *prefix = NULL;

	context_file = fopen(filename, "r");
	if (!context_file) {
		fprintf(stderr, "Error opening %s: %s\n",
			    filename, strerror(errno));
		return -1;
	}

	line_num = 0;
	rc = 0;
	while (getline(&line_buf, &line_len, context_file) > 0) {
		rc = process_line(rec, filename, prefix, line_buf, ++line_num);
		if (rc || ctx_err) {
			/* With -p option need to check and fail if ctx err as
			 * process_line() context validation on Linux does not
			 * return an error, but does print the error line to
			 * stderr. Android will set both to error and print
			 * the error line. */
			rc = -1;
			goto out;
		}
	}
out:
	free(line_buf);
	fclose(context_file);
	return rc;
}

/*
 * File Format
 *
 * u32 - magic number
 * u32 - version
 * u32 - length of pcre version EXCLUDING nul
 * char - pcre version string EXCLUDING nul
 * u32 - number of stems
 * ** Stems
 *	u32  - length of stem EXCLUDING nul
 *	char - stem char array INCLUDING nul
 * u32 - number of regexs
 * ** Regexes
 *	u32  - length of upcoming context INCLUDING nul
 *	char - char array of the raw context
 *	u32  - length of the upcoming regex_str
 *	char - char array of the original regex string including the stem.
 *	u32  - mode bits for >= SELINUX_COMPILED_FCONTEXT_MODE
 *	       mode_t for <= SELINUX_COMPILED_FCONTEXT_PCRE_VERS
 *	s32  - stemid associated with the regex
 *	u32  - spec has meta characters
 *	u32  - The specs prefix_len if >= SELINUX_COMPILED_FCONTEXT_PREFIX_LEN
 *	u32  - data length of the pcre regex
 *	char - a bufer holding the raw pcre regex info
 *	u32  - data length of the pcre regex study daya
 *	char - a buffer holding the raw pcre regex study data
 */
static int write_binary_file(struct saved_data *data, int fd,
			     int do_write_precompregex)
{
	struct spec *specs = data->spec_arr;
	FILE *bin_file;
	size_t len;
	uint32_t magic = SELINUX_MAGIC_COMPILED_FCONTEXT;
	uint32_t section_len;
	uint32_t i;
	int rc;
	const char *reg_version;
	const char *reg_arch;

	bin_file = fdopen(fd, "w");
	if (!bin_file) {
		perror("fopen output_file");
		exit(EXIT_FAILURE);
	}

	/* write some magic number */
	len = fwrite(&magic, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;

	/* write the version */
	section_len = SELINUX_COMPILED_FCONTEXT_MAX_VERS;
	len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;

	/* write version of the regex back-end */
	reg_version = regex_version();
	if (!reg_version)
		goto err;
	section_len = strlen(reg_version);
	len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;
	len = fwrite(reg_version, sizeof(char), section_len, bin_file);
	if (len != section_len)
		goto err;

	/* write regex arch string */
	reg_arch = regex_arch_string();
	if (!reg_arch)
		goto err;
	section_len = strlen(reg_arch);
	len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;
	len = fwrite(reg_arch, sizeof(char), section_len, bin_file);
	if (len != section_len)
		goto err;

	/* write the number of stems coming */
	section_len = data->num_stems;
	len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;

	for (i = 0; i < section_len; i++) {
		char *stem = data->stem_arr[i].buf;
		uint32_t stem_len = data->stem_arr[i].len;

		/* write the strlen (aka no nul) */
		len = fwrite(&stem_len, sizeof(uint32_t), 1, bin_file);
		if (len != 1)
			goto err;

		/* include the nul in the file */
		stem_len += 1;
		len = fwrite(stem, sizeof(char), stem_len, bin_file);
		if (len != stem_len)
			goto err;
	}

	/* write the number of regexes coming */
	section_len = data->nspec;
	len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
	if (len != 1)
		goto err;

	for (i = 0; i < section_len; i++) {
		char *context = specs[i].lr.ctx_raw;
		char *regex_str = specs[i].regex_str;
		mode_t mode = specs[i].mode;
		size_t prefix_len = specs[i].prefix_len;
		int32_t stem_id = specs[i].stem_id;
		struct regex_data *re = specs[i].regex;
		uint32_t to_write;

		/* length of the context string (including nul) */
		to_write = strlen(context) + 1;
		len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
		if (len != 1)
			goto err;

		/* original context strin (including nul) */
		len = fwrite(context, sizeof(char), to_write, bin_file);
		if (len != to_write)
			goto err;

		/* length of the original regex string (including nul) */
		to_write = strlen(regex_str) + 1;
		len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
		if (len != 1)
			goto err;

		/* original regex string */
		len = fwrite(regex_str, sizeof(char), to_write, bin_file);
		if (len != to_write)
			goto err;

		/* binary F_MODE bits */
		to_write = mode;
		len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
		if (len != 1)
			goto err;

		/* stem for this regex (could be -1) */
		len = fwrite(&stem_id, sizeof(stem_id), 1, bin_file);
		if (len != 1)
			goto err;

		/* does this spec have a metaChar? */
		to_write = specs[i].hasMetaChars;
		len = fwrite(&to_write, sizeof(to_write), 1, bin_file);
		if (len != 1)
			goto err;

		/* For SELINUX_COMPILED_FCONTEXT_PREFIX_LEN */
		to_write = prefix_len;
		len = fwrite(&to_write, sizeof(to_write), 1, bin_file);
		if (len != 1)
			goto err;

		/* Write regex related data */
		rc = regex_writef(re, bin_file, do_write_precompregex);
		if (rc < 0)
			goto err;
	}

	rc = 0;
out:
	fclose(bin_file);
	return rc;
err:
	rc = -1;
	goto out;
}

static void free_specs(struct saved_data *data)
{
	struct spec *specs = data->spec_arr;
	unsigned int num_entries = data->nspec;
	unsigned int i;

	for (i = 0; i < num_entries; i++) {
		free(specs[i].lr.ctx_raw);
		free(specs[i].lr.ctx_trans);
		free(specs[i].regex_str);
		free(specs[i].type_str);
		regex_data_free(specs[i].regex);
	}
	free(specs);

	num_entries = data->num_stems;
	for (i = 0; i < num_entries; i++)
		free(data->stem_arr[i].buf);
	free(data->stem_arr);

	memset(data, 0, sizeof(*data));
}

static __attribute__ ((__noreturn__)) void usage(const char *progname)
{
	fprintf(stderr,
	    "usage: %s [-o out_file] [-p policy_file] fc_file\n"
	    "Where:\n\t"
	    "-o       Optional file name of the PCRE formatted binary\n\t"
	    "         file to be output. If not specified the default\n\t"
	    "         will be fc_file with the .bin suffix appended.\n\t"
	    "-p       Optional binary policy file that will be used to\n\t"
	    "         validate contexts defined in the fc_file.\n\t"
	    "-r       Omit precompiled regular expressions from the output.\n\t"
	    "         (PCRE2 only. Compiled PCRE2 regular expressions are\n\t"
	    "         not portable across architectures. Use this flag\n\t"
	    "         if you know that you build for an incompatible\n\t"
	    "         architecture to save space. When linked against\n\t"
	    "         PCRE1 this flag is ignored.)\n\t"
	    "-i       Print regular expression info end exit. That is, back\n\t"
	    "         end version and architecture identifier.\n\t"
	    "         Arch identifier format (PCRE2):\n\t"
	    "         <pointer width>-<size type width>-<endianness>, e.g.,\n\t"
	    "         \"8-8-el\" for x86_64.\n\t"
	    "fc_file  The text based file contexts file to be processed.\n",
	    progname);
		exit(EXIT_FAILURE);
}

int main(int argc, char *argv[])
{
	const char *path = NULL;
	const char *out_file = NULL;
	int do_write_precompregex = 1;
	char stack_path[PATH_MAX + 1];
	char *tmp = NULL;
	int fd, rc, opt;
	FILE *policy_fp = NULL;
	struct stat buf;
	struct selabel_handle *rec = NULL;
	struct saved_data *data = NULL;

	if (argc < 2)
		usage(argv[0]);

	while ((opt = getopt(argc, argv, "io:p:r")) > 0) {
		switch (opt) {
		case 'o':
			out_file = optarg;
			break;
		case 'p':
			policy_file = optarg;
			break;
		case 'r':
			do_write_precompregex = 0;
			break;
		case 'i':
			printf("%s (%s)\n", regex_version(),
					regex_arch_string());
			return 0;
		default:
			usage(argv[0]);
		}
	}

	if (optind >= argc)
		usage(argv[0]);

	path = argv[optind];
	if (stat(path, &buf) < 0) {
		fprintf(stderr, "%s: could not stat: %s: %s\n", argv[0], path, strerror(errno));
		exit(EXIT_FAILURE);
	}

	/* Open binary policy if supplied. */
	if (policy_file) {
		policy_fp = fopen(policy_file, "r");

		if (!policy_fp) {
			fprintf(stderr, "%s: failed to open %s: %s\n",
				argv[0], policy_file, strerror(errno));
			exit(EXIT_FAILURE);
		}

		if (sepol_set_policydb_from_file(policy_fp) < 0) {
			fprintf(stderr, "%s: failed to load policy from %s\n",
				argv[0], policy_file);
			fclose(policy_fp);
			exit(EXIT_FAILURE);
		}
	}

	/* Generate dummy handle for process_line() function */
	rec = (struct selabel_handle *)calloc(1, sizeof(*rec));
	if (!rec) {
		fprintf(stderr, "%s: calloc failed: %s\n", argv[0], strerror(errno));
		if (policy_fp)
			fclose(policy_fp);
		exit(EXIT_FAILURE);
	}
	rec->backend = SELABEL_CTX_FILE;

	/* Need to set validation on to get the bin file generated by the
	 * process_line function, however as the bin file being generated
	 * may not be related to the currently loaded policy (that it
	 * would be validated against), then set callback to ignore any
	 * validation - unless the -p option is used in which case if an
	 * error is detected, the process will be aborted. */
	rec->validating = 1;
	selinux_set_callback(SELINUX_CB_VALIDATE,
			    (union selinux_callback)&validate_context);

	data = (struct saved_data *)calloc(1, sizeof(*data));
	if (!data) {
		fprintf(stderr, "%s: calloc failed: %s\n", argv[0], strerror(errno));
		free(rec);
		if (policy_fp)
			fclose(policy_fp);
		exit(EXIT_FAILURE);
	}

	rec->data = data;

	rc = process_file(rec, path);
	if (rc < 0) {
		fprintf(stderr, "%s: process_file failed\n", argv[0]);
		goto err;
	}

	rc = sort_specs(data);
	if (rc) {
		fprintf(stderr, "%s: sort_specs failed\n", argv[0]);
		goto err;
	}

	if (out_file)
		rc = snprintf(stack_path, sizeof(stack_path), "%s", out_file);
	else
		rc = snprintf(stack_path, sizeof(stack_path), "%s.bin", path);

	if (rc < 0 || rc >= (int)sizeof(stack_path)) {
		fprintf(stderr, "%s: snprintf failed\n", argv[0]);
		goto err;
	}

	tmp = malloc(strlen(stack_path) + 7);
	if (!tmp) {
		fprintf(stderr, "%s: malloc failed: %s\n", argv[0], strerror(errno));
		goto err;
	}

	rc = sprintf(tmp, "%sXXXXXX", stack_path);
	if (rc < 0) {
		fprintf(stderr, "%s: sprintf failed\n", argv[0]);
		goto err;
	}

	fd  = mkstemp(tmp);
	if (fd < 0) {
		fprintf(stderr, "%s: mkstemp %s failed: %s\n", argv[0], tmp, strerror(errno));
		goto err;
	}

	rc = fchmod(fd, buf.st_mode);
	if (rc < 0) {
		fprintf(stderr, "%s: fchmod %s failed: %s\n", argv[0], tmp, strerror(errno));
		goto err_unlink;
	}

	rc = write_binary_file(data, fd, do_write_precompregex);
	if (rc < 0) {
		fprintf(stderr, "%s: write_binary_file %s failed\n", argv[0], tmp);
		goto err_unlink;
	}

	rc = rename(tmp, stack_path);
	if (rc < 0) {
		fprintf(stderr, "%s: rename %s -> %s failed: %s\n", argv[0], tmp, stack_path, strerror(errno));
		goto err_unlink;
	}

	rc = 0;
out:
	if (policy_fp)
		fclose(policy_fp);

	free_specs(data);
	free(rec);
	free(data);
	free(tmp);
	return rc;

err_unlink:
	unlink(tmp);
err:
	rc = -1;
	goto out;
}