summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_template_lib.c
blob: 7320b76b1c621778686da4e3e59e1511a01bb55a (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013 Politecnico di Torino, Italy
 *                    TORSEC group -- https://security.polito.it
 *
 * Author: Roberto Sassu <roberto.sassu@polito.it>
 *
 * File: ima_template_lib.c
 *      Library of supported template fields.
 */

#include "ima_template_lib.h"

static bool ima_template_hash_algo_allowed(u8 algo)
{
	if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
		return true;

	return false;
}

enum data_formats {
	DATA_FMT_DIGEST = 0,
	DATA_FMT_DIGEST_WITH_ALGO,
	DATA_FMT_STRING,
	DATA_FMT_HEX
};

static int ima_write_template_field_data(const void *data, const u32 datalen,
					 enum data_formats datafmt,
					 struct ima_field_data *field_data)
{
	u8 *buf, *buf_ptr;
	u32 buflen = datalen;

	if (datafmt == DATA_FMT_STRING)
		buflen = datalen + 1;

	buf = kzalloc(buflen, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	memcpy(buf, data, datalen);

	/*
	 * Replace all space characters with underscore for event names and
	 * strings. This avoid that, during the parsing of a measurements list,
	 * filenames with spaces or that end with the suffix ' (deleted)' are
	 * split into multiple template fields (the space is the delimitator
	 * character for measurements lists in ASCII format).
	 */
	if (datafmt == DATA_FMT_STRING) {
		for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
			if (*buf_ptr == ' ')
				*buf_ptr = '_';
	}

	field_data->data = buf;
	field_data->len = buflen;
	return 0;
}

static void ima_show_template_data_ascii(struct seq_file *m,
					 enum ima_show_type show,
					 enum data_formats datafmt,
					 struct ima_field_data *field_data)
{
	u8 *buf_ptr = field_data->data;
	u32 buflen = field_data->len;

	switch (datafmt) {
	case DATA_FMT_DIGEST_WITH_ALGO:
		buf_ptr = strnchr(field_data->data, buflen, ':');
		if (buf_ptr != field_data->data)
			seq_printf(m, "%s", field_data->data);

		/* skip ':' and '\0' */
		buf_ptr += 2;
		buflen -= buf_ptr - field_data->data;
		/* fall through */
	case DATA_FMT_DIGEST:
	case DATA_FMT_HEX:
		if (!buflen)
			break;
		ima_print_digest(m, buf_ptr, buflen);
		break;
	case DATA_FMT_STRING:
		seq_printf(m, "%s", buf_ptr);
		break;
	default:
		break;
	}
}

static void ima_show_template_data_binary(struct seq_file *m,
					  enum ima_show_type show,
					  enum data_formats datafmt,
					  struct ima_field_data *field_data)
{
	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
	    strlen(field_data->data) : field_data->len;

	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
		u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);

		ima_putc(m, &field_len, sizeof(field_len));
	}

	if (!len)
		return;

	ima_putc(m, field_data->data, len);
}

static void ima_show_template_field_data(struct seq_file *m,
					 enum ima_show_type show,
					 enum data_formats datafmt,
					 struct ima_field_data *field_data)
{
	switch (show) {
	case IMA_SHOW_ASCII:
		ima_show_template_data_ascii(m, show, datafmt, field_data);
		break;
	case IMA_SHOW_BINARY:
	case IMA_SHOW_BINARY_NO_FIELD_LEN:
	case IMA_SHOW_BINARY_OLD_STRING_FMT:
		ima_show_template_data_binary(m, show, datafmt, field_data);
		break;
	default:
		break;
	}
}

void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
			      struct ima_field_data *field_data)
{
	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
}

void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
				 struct ima_field_data *field_data)
{
	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
				     field_data);
}

void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
			      struct ima_field_data *field_data)
{
	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
}

void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
			   struct ima_field_data *field_data)
{
	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
}

void ima_show_template_buf(struct seq_file *m, enum ima_show_type show,
			   struct ima_field_data *field_data)
{
	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
}

/**
 * ima_parse_buf() - Parses lengths and data from an input buffer
 * @bufstartp:       Buffer start address.
 * @bufendp:         Buffer end address.
 * @bufcurp:         Pointer to remaining (non-parsed) data.
 * @maxfields:       Length of fields array.
 * @fields:          Array containing lengths and pointers of parsed data.
 * @curfields:       Number of array items containing parsed data.
 * @len_mask:        Bitmap (if bit is set, data length should not be parsed).
 * @enforce_mask:    Check if curfields == maxfields and/or bufcurp == bufendp.
 * @bufname:         String identifier of the input buffer.
 *
 * Return: 0 on success, -EINVAL on error.
 */
int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
		  int maxfields, struct ima_field_data *fields, int *curfields,
		  unsigned long *len_mask, int enforce_mask, char *bufname)
{
	void *bufp = bufstartp;
	int i;

	for (i = 0; i < maxfields; i++) {
		if (len_mask == NULL || !test_bit(i, len_mask)) {
			if (bufp > (bufendp - sizeof(u32)))
				break;

			fields[i].len = *(u32 *)bufp;
			if (ima_canonical_fmt)
				fields[i].len = le32_to_cpu(fields[i].len);

			bufp += sizeof(u32);
		}

		if (bufp > (bufendp - fields[i].len))
			break;

		fields[i].data = bufp;
		bufp += fields[i].len;
	}

	if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
		pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
		       bufname, maxfields, i);
		return -EINVAL;
	}

	if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
		pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
		       bufname, bufendp, bufp);
		return -EINVAL;
	}

	if (curfields)
		*curfields = i;

	if (bufcurp)
		*bufcurp = bufp;

	return 0;
}

static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize,
				       u8 hash_algo,
				       struct ima_field_data *field_data)
{
	/*
	 * digest formats:
	 *  - DATA_FMT_DIGEST: digest
	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
	 *    where <hash algo> is provided if the hash algoritm is not
	 *    SHA1 or MD5
	 */
	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
	enum data_formats fmt = DATA_FMT_DIGEST;
	u32 offset = 0;

	if (hash_algo < HASH_ALGO__LAST) {
		fmt = DATA_FMT_DIGEST_WITH_ALGO;
		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
				   hash_algo_name[hash_algo]);
		buffer[offset] = ':';
		offset += 2;
	}

	if (digest)
		memcpy(buffer + offset, digest, digestsize);
	else
		/*
		 * If digest is NULL, the event being recorded is a violation.
		 * Make room for the digest by increasing the offset of
		 * IMA_DIGEST_SIZE.
		 */
		offset += IMA_DIGEST_SIZE;

	return ima_write_template_field_data(buffer, offset + digestsize,
					     fmt, field_data);
}

/*
 * This function writes the digest of an event (with size limit).
 */
int ima_eventdigest_init(struct ima_event_data *event_data,
			 struct ima_field_data *field_data)
{
	struct {
		struct ima_digest_data hdr;
		char digest[IMA_MAX_DIGEST_SIZE];
	} hash;
	u8 *cur_digest = NULL;
	u32 cur_digestsize = 0;
	struct inode *inode;
	int result;

	memset(&hash, 0, sizeof(hash));

	if (event_data->violation)	/* recording a violation. */
		goto out;

	if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
		cur_digest = event_data->iint->ima_hash->digest;
		cur_digestsize = event_data->iint->ima_hash->length;
		goto out;
	}

	if (!event_data->file)	/* missing info to re-calculate the digest */
		return -EINVAL;

	inode = file_inode(event_data->file);
	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
	    ima_hash_algo : HASH_ALGO_SHA1;
	result = ima_calc_file_hash(event_data->file, &hash.hdr);
	if (result) {
		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
				    event_data->filename, "collect_data",
				    "failed", result, 0);
		return result;
	}
	cur_digest = hash.hdr.digest;
	cur_digestsize = hash.hdr.length;
out:
	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
					   HASH_ALGO__LAST, field_data);
}

/*
 * This function writes the digest of an event (without size limit).
 */
int ima_eventdigest_ng_init(struct ima_event_data *event_data,
			    struct ima_field_data *field_data)
{
	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
	u32 cur_digestsize = 0;

	if (event_data->violation)	/* recording a violation. */
		goto out;

	cur_digest = event_data->iint->ima_hash->digest;
	cur_digestsize = event_data->iint->ima_hash->length;

	hash_algo = event_data->iint->ima_hash->algo;
out:
	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
					   hash_algo, field_data);
}

/*
 * This function writes the digest of the file which is expected to match the
 * digest contained in the file's appended signature.
 */
int ima_eventdigest_modsig_init(struct ima_event_data *event_data,
				struct ima_field_data *field_data)
{
	enum hash_algo hash_algo;
	const u8 *cur_digest;
	u32 cur_digestsize;

	if (!event_data->modsig)
		return 0;

	if (event_data->violation) {
		/* Recording a violation. */
		hash_algo = HASH_ALGO_SHA1;
		cur_digest = NULL;
		cur_digestsize = 0;
	} else {
		int rc;

		rc = ima_get_modsig_digest(event_data->modsig, &hash_algo,
					   &cur_digest, &cur_digestsize);
		if (rc)
			return rc;
		else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0)
			/* There was some error collecting the digest. */
			return -EINVAL;
	}

	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
					   hash_algo, field_data);
}

static int ima_eventname_init_common(struct ima_event_data *event_data,
				     struct ima_field_data *field_data,
				     bool size_limit)
{
	const char *cur_filename = NULL;
	u32 cur_filename_len = 0;

	BUG_ON(event_data->filename == NULL && event_data->file == NULL);

	if (event_data->filename) {
		cur_filename = event_data->filename;
		cur_filename_len = strlen(event_data->filename);

		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
			goto out;
	}

	if (event_data->file) {
		cur_filename = event_data->file->f_path.dentry->d_name.name;
		cur_filename_len = strlen(cur_filename);
	} else
		/*
		 * Truncate filename if the latter is too long and
		 * the file descriptor is not available.
		 */
		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
out:
	return ima_write_template_field_data(cur_filename, cur_filename_len,
					     DATA_FMT_STRING, field_data);
}

/*
 * This function writes the name of an event (with size limit).
 */
int ima_eventname_init(struct ima_event_data *event_data,
		       struct ima_field_data *field_data)
{
	return ima_eventname_init_common(event_data, field_data, true);
}

/*
 * This function writes the name of an event (without size limit).
 */
int ima_eventname_ng_init(struct ima_event_data *event_data,
			  struct ima_field_data *field_data)
{
	return ima_eventname_init_common(event_data, field_data, false);
}

/*
 *  ima_eventsig_init - include the file signature as part of the template data
 */
int ima_eventsig_init(struct ima_event_data *event_data,
		      struct ima_field_data *field_data)
{
	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;

	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
		return 0;

	return ima_write_template_field_data(xattr_value, event_data->xattr_len,
					     DATA_FMT_HEX, field_data);
}

/*
 *  ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
 *  template data.
 */
int ima_eventbuf_init(struct ima_event_data *event_data,
		      struct ima_field_data *field_data)
{
	if ((!event_data->buf) || (event_data->buf_len == 0))
		return 0;

	return ima_write_template_field_data(event_data->buf,
					     event_data->buf_len, DATA_FMT_HEX,
					     field_data);
}

/*
 *  ima_eventmodsig_init - include the appended file signature as part of the
 *  template data
 */
int ima_eventmodsig_init(struct ima_event_data *event_data,
			 struct ima_field_data *field_data)
{
	const void *data;
	u32 data_len;
	int rc;

	if (!event_data->modsig)
		return 0;

	/*
	 * modsig is a runtime structure containing pointers. Get its raw data
	 * instead.
	 */
	rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len);
	if (rc)
		return rc;

	return ima_write_template_field_data(data, data_len, DATA_FMT_HEX,
					     field_data);
}