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 
14 static 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 
22 enum data_formats {
23 	DATA_FMT_DIGEST = 0,
24 	DATA_FMT_DIGEST_WITH_ALGO,
25 	DATA_FMT_STRING,
26 	DATA_FMT_HEX
27 };
28 
29 static 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 
63 static 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 
95 static 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 
115 static 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 
134 void 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 
140 void 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 
147 void 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 
153 void 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 
159 void 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  */
179 int 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 
226 static 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  */
266 int 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;
322 out:
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  */
330 int 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;
343 out:
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  */
352 int 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 
383 static 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;
409 out:
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  */
417 int 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  */
426 int 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  */
435 int 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  */
451 int 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  */
466 int 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