1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2013 Politecnico di Torino, Italy
4 *                    TORSEC group -- https://security.polito.it
5 *
6 * Author: Roberto Sassu <roberto.sassu@polito.it>
7 *
8 * File: ima_template_lib.c
9 *      Library of supported template fields.
10 */
11
12#include "ima_template_lib.h"
13
14static bool ima_template_hash_algo_allowed(u8 algo)
15{
16	if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
17		return true;
18
19	return false;
20}
21
22enum data_formats {
23	DATA_FMT_DIGEST = 0,
24	DATA_FMT_DIGEST_WITH_ALGO,
25	DATA_FMT_STRING,
26	DATA_FMT_HEX
27};
28
29static int ima_write_template_field_data(const void *data, const u32 datalen,
30					 enum data_formats datafmt,
31					 struct ima_field_data *field_data)
32{
33	u8 *buf, *buf_ptr;
34	u32 buflen = datalen;
35
36	if (datafmt == DATA_FMT_STRING)
37		buflen = datalen + 1;
38
39	buf = kzalloc(buflen, GFP_KERNEL);
40	if (!buf)
41		return -ENOMEM;
42
43	memcpy(buf, data, datalen);
44
45	/*
46	 * Replace all space characters with underscore for event names and
47	 * strings. This avoid that, during the parsing of a measurements list,
48	 * filenames with spaces or that end with the suffix ' (deleted)' are
49	 * split into multiple template fields (the space is the delimitator
50	 * character for measurements lists in ASCII format).
51	 */
52	if (datafmt == DATA_FMT_STRING) {
53		for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
54			if (*buf_ptr == ' ')
55				*buf_ptr = '_';
56	}
57
58	field_data->data = buf;
59	field_data->len = buflen;
60	return 0;
61}
62
63static void ima_show_template_data_ascii(struct seq_file *m,
64					 enum ima_show_type show,
65					 enum data_formats datafmt,
66					 struct ima_field_data *field_data)
67{
68	u8 *buf_ptr = field_data->data;
69	u32 buflen = field_data->len;
70
71	switch (datafmt) {
72	case DATA_FMT_DIGEST_WITH_ALGO:
73		buf_ptr = strnchr(field_data->data, buflen, ':');
74		if (buf_ptr != field_data->data)
75			seq_printf(m, "%s", field_data->data);
76
77		/* skip ':' and '\0' */
78		buf_ptr += 2;
79		buflen -= buf_ptr - field_data->data;
80		fallthrough;
81	case DATA_FMT_DIGEST:
82	case DATA_FMT_HEX:
83		if (!buflen)
84			break;
85		ima_print_digest(m, buf_ptr, buflen);
86		break;
87	case DATA_FMT_STRING:
88		seq_printf(m, "%s", buf_ptr);
89		break;
90	default:
91		break;
92	}
93}
94
95static void ima_show_template_data_binary(struct seq_file *m,
96					  enum ima_show_type show,
97					  enum data_formats datafmt,
98					  struct ima_field_data *field_data)
99{
100	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
101	    strlen(field_data->data) : field_data->len;
102
103	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
104		u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
105
106		ima_putc(m, &field_len, sizeof(field_len));
107	}
108
109	if (!len)
110		return;
111
112	ima_putc(m, field_data->data, len);
113}
114
115static void ima_show_template_field_data(struct seq_file *m,
116					 enum ima_show_type show,
117					 enum data_formats datafmt,
118					 struct ima_field_data *field_data)
119{
120	switch (show) {
121	case IMA_SHOW_ASCII:
122		ima_show_template_data_ascii(m, show, datafmt, field_data);
123		break;
124	case IMA_SHOW_BINARY:
125	case IMA_SHOW_BINARY_NO_FIELD_LEN:
126	case IMA_SHOW_BINARY_OLD_STRING_FMT:
127		ima_show_template_data_binary(m, show, datafmt, field_data);
128		break;
129	default:
130		break;
131	}
132}
133
134void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
135			      struct ima_field_data *field_data)
136{
137	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
138}
139
140void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
141				 struct ima_field_data *field_data)
142{
143	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
144				     field_data);
145}
146
147void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
148			      struct ima_field_data *field_data)
149{
150	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
151}
152
153void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
154			   struct ima_field_data *field_data)
155{
156	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
157}
158
159void ima_show_template_buf(struct seq_file *m, enum ima_show_type show,
160			   struct ima_field_data *field_data)
161{
162	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
163}
164
165/**
166 * ima_parse_buf() - Parses lengths and data from an input buffer
167 * @bufstartp:       Buffer start address.
168 * @bufendp:         Buffer end address.
169 * @bufcurp:         Pointer to remaining (non-parsed) data.
170 * @maxfields:       Length of fields array.
171 * @fields:          Array containing lengths and pointers of parsed data.
172 * @curfields:       Number of array items containing parsed data.
173 * @len_mask:        Bitmap (if bit is set, data length should not be parsed).
174 * @enforce_mask:    Check if curfields == maxfields and/or bufcurp == bufendp.
175 * @bufname:         String identifier of the input buffer.
176 *
177 * Return: 0 on success, -EINVAL on error.
178 */
179int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
180		  int maxfields, struct ima_field_data *fields, int *curfields,
181		  unsigned long *len_mask, int enforce_mask, char *bufname)
182{
183	void *bufp = bufstartp;
184	int i;
185
186	for (i = 0; i < maxfields; i++) {
187		if (len_mask == NULL || !test_bit(i, len_mask)) {
188			if (bufp > (bufendp - sizeof(u32)))
189				break;
190
191			fields[i].len = *(u32 *)bufp;
192			if (ima_canonical_fmt)
193				fields[i].len = le32_to_cpu(fields[i].len);
194
195			bufp += sizeof(u32);
196		}
197
198		if (bufp > (bufendp - fields[i].len))
199			break;
200
201		fields[i].data = bufp;
202		bufp += fields[i].len;
203	}
204
205	if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
206		pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
207		       bufname, maxfields, i);
208		return -EINVAL;
209	}
210
211	if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
212		pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
213		       bufname, bufendp, bufp);
214		return -EINVAL;
215	}
216
217	if (curfields)
218		*curfields = i;
219
220	if (bufcurp)
221		*bufcurp = bufp;
222
223	return 0;
224}
225
226static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize,
227				       u8 hash_algo,
228				       struct ima_field_data *field_data)
229{
230	/*
231	 * digest formats:
232	 *  - DATA_FMT_DIGEST: digest
233	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
234	 *    where <hash algo> is provided if the hash algoritm is not
235	 *    SHA1 or MD5
236	 */
237	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
238	enum data_formats fmt = DATA_FMT_DIGEST;
239	u32 offset = 0;
240
241	if (hash_algo < HASH_ALGO__LAST) {
242		fmt = DATA_FMT_DIGEST_WITH_ALGO;
243		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
244				   hash_algo_name[hash_algo]);
245		buffer[offset] = ':';
246		offset += 2;
247	}
248
249	if (digest)
250		memcpy(buffer + offset, digest, digestsize);
251	else
252		/*
253		 * If digest is NULL, the event being recorded is a violation.
254		 * Make room for the digest by increasing the offset of
255		 * IMA_DIGEST_SIZE.
256		 */
257		offset += IMA_DIGEST_SIZE;
258
259	return ima_write_template_field_data(buffer, offset + digestsize,
260					     fmt, field_data);
261}
262
263/*
264 * This function writes the digest of an event (with size limit).
265 */
266int ima_eventdigest_init(struct ima_event_data *event_data,
267			 struct ima_field_data *field_data)
268{
269	struct {
270		struct ima_digest_data hdr;
271		char digest[IMA_MAX_DIGEST_SIZE];
272	} hash;
273	u8 *cur_digest = NULL;
274	u32 cur_digestsize = 0;
275	struct inode *inode;
276	int result;
277
278	memset(&hash, 0, sizeof(hash));
279
280	if (event_data->violation)	/* recording a violation. */
281		goto out;
282
283	if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
284		cur_digest = event_data->iint->ima_hash->digest;
285		cur_digestsize = event_data->iint->ima_hash->length;
286		goto out;
287	}
288
289	if ((const char *)event_data->filename == boot_aggregate_name) {
290		if (ima_tpm_chip) {
291			hash.hdr.algo = HASH_ALGO_SHA1;
292			result = ima_calc_boot_aggregate(&hash.hdr);
293
294			/* algo can change depending on available PCR banks */
295			if (!result && hash.hdr.algo != HASH_ALGO_SHA1)
296				result = -EINVAL;
297
298			if (result < 0)
299				memset(&hash, 0, sizeof(hash));
300		}
301
302		cur_digest = hash.hdr.digest;
303		cur_digestsize = hash_digest_size[HASH_ALGO_SHA1];
304		goto out;
305	}
306
307	if (!event_data->file)	/* missing info to re-calculate the digest */
308		return -EINVAL;
309
310	inode = file_inode(event_data->file);
311	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
312	    ima_hash_algo : HASH_ALGO_SHA1;
313	result = ima_calc_file_hash(event_data->file, &hash.hdr);
314	if (result) {
315		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
316				    event_data->filename, "collect_data",
317				    "failed", result, 0);
318		return result;
319	}
320	cur_digest = hash.hdr.digest;
321	cur_digestsize = hash.hdr.length;
322out:
323	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
324					   HASH_ALGO__LAST, field_data);
325}
326
327/*
328 * This function writes the digest of an event (without size limit).
329 */
330int ima_eventdigest_ng_init(struct ima_event_data *event_data,
331			    struct ima_field_data *field_data)
332{
333	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
334	u32 cur_digestsize = 0;
335
336	if (event_data->violation)	/* recording a violation. */
337		goto out;
338
339	cur_digest = event_data->iint->ima_hash->digest;
340	cur_digestsize = event_data->iint->ima_hash->length;
341
342	hash_algo = event_data->iint->ima_hash->algo;
343out:
344	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
345					   hash_algo, field_data);
346}
347
348/*
349 * This function writes the digest of the file which is expected to match the
350 * digest contained in the file's appended signature.
351 */
352int ima_eventdigest_modsig_init(struct ima_event_data *event_data,
353				struct ima_field_data *field_data)
354{
355	enum hash_algo hash_algo;
356	const u8 *cur_digest;
357	u32 cur_digestsize;
358
359	if (!event_data->modsig)
360		return 0;
361
362	if (event_data->violation) {
363		/* Recording a violation. */
364		hash_algo = HASH_ALGO_SHA1;
365		cur_digest = NULL;
366		cur_digestsize = 0;
367	} else {
368		int rc;
369
370		rc = ima_get_modsig_digest(event_data->modsig, &hash_algo,
371					   &cur_digest, &cur_digestsize);
372		if (rc)
373			return rc;
374		else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0)
375			/* There was some error collecting the digest. */
376			return -EINVAL;
377	}
378
379	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
380					   hash_algo, field_data);
381}
382
383static int ima_eventname_init_common(struct ima_event_data *event_data,
384				     struct ima_field_data *field_data,
385				     bool size_limit)
386{
387	const char *cur_filename = NULL;
388	u32 cur_filename_len = 0;
389
390	BUG_ON(event_data->filename == NULL && event_data->file == NULL);
391
392	if (event_data->filename) {
393		cur_filename = event_data->filename;
394		cur_filename_len = strlen(event_data->filename);
395
396		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
397			goto out;
398	}
399
400	if (event_data->file) {
401		cur_filename = event_data->file->f_path.dentry->d_name.name;
402		cur_filename_len = strlen(cur_filename);
403	} else
404		/*
405		 * Truncate filename if the latter is too long and
406		 * the file descriptor is not available.
407		 */
408		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
409out:
410	return ima_write_template_field_data(cur_filename, cur_filename_len,
411					     DATA_FMT_STRING, field_data);
412}
413
414/*
415 * This function writes the name of an event (with size limit).
416 */
417int ima_eventname_init(struct ima_event_data *event_data,
418		       struct ima_field_data *field_data)
419{
420	return ima_eventname_init_common(event_data, field_data, true);
421}
422
423/*
424 * This function writes the name of an event (without size limit).
425 */
426int ima_eventname_ng_init(struct ima_event_data *event_data,
427			  struct ima_field_data *field_data)
428{
429	return ima_eventname_init_common(event_data, field_data, false);
430}
431
432/*
433 *  ima_eventsig_init - include the file signature as part of the template data
434 */
435int ima_eventsig_init(struct ima_event_data *event_data,
436		      struct ima_field_data *field_data)
437{
438	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
439
440	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
441		return 0;
442
443	return ima_write_template_field_data(xattr_value, event_data->xattr_len,
444					     DATA_FMT_HEX, field_data);
445}
446
447/*
448 *  ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
449 *  template data.
450 */
451int ima_eventbuf_init(struct ima_event_data *event_data,
452		      struct ima_field_data *field_data)
453{
454	if ((!event_data->buf) || (event_data->buf_len == 0))
455		return 0;
456
457	return ima_write_template_field_data(event_data->buf,
458					     event_data->buf_len, DATA_FMT_HEX,
459					     field_data);
460}
461
462/*
463 *  ima_eventmodsig_init - include the appended file signature as part of the
464 *  template data
465 */
466int ima_eventmodsig_init(struct ima_event_data *event_data,
467			 struct ima_field_data *field_data)
468{
469	const void *data;
470	u32 data_len;
471	int rc;
472
473	if (!event_data->modsig)
474		return 0;
475
476	/*
477	 * modsig is a runtime structure containing pointers. Get its raw data
478	 * instead.
479	 */
480	rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len);
481	if (rc)
482		return rc;
483
484	return ima_write_template_field_data(data, data_len, DATA_FMT_HEX,
485					     field_data);
486}
487