1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2013 Politecnico di Torino, Italy
4  *                    TORSEC group -- http://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 		/* fall through */
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 (!event_data->file)	/* missing info to re-calculate the digest */
290 		return -EINVAL;
291 
292 	inode = file_inode(event_data->file);
293 	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
294 	    ima_hash_algo : HASH_ALGO_SHA1;
295 	result = ima_calc_file_hash(event_data->file, &hash.hdr);
296 	if (result) {
297 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
298 				    event_data->filename, "collect_data",
299 				    "failed", result, 0);
300 		return result;
301 	}
302 	cur_digest = hash.hdr.digest;
303 	cur_digestsize = hash.hdr.length;
304 out:
305 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
306 					   HASH_ALGO__LAST, field_data);
307 }
308 
309 /*
310  * This function writes the digest of an event (without size limit).
311  */
312 int ima_eventdigest_ng_init(struct ima_event_data *event_data,
313 			    struct ima_field_data *field_data)
314 {
315 	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
316 	u32 cur_digestsize = 0;
317 
318 	if (event_data->violation)	/* recording a violation. */
319 		goto out;
320 
321 	cur_digest = event_data->iint->ima_hash->digest;
322 	cur_digestsize = event_data->iint->ima_hash->length;
323 
324 	hash_algo = event_data->iint->ima_hash->algo;
325 out:
326 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
327 					   hash_algo, field_data);
328 }
329 
330 /*
331  * This function writes the digest of the file which is expected to match the
332  * digest contained in the file's appended signature.
333  */
334 int ima_eventdigest_modsig_init(struct ima_event_data *event_data,
335 				struct ima_field_data *field_data)
336 {
337 	enum hash_algo hash_algo;
338 	const u8 *cur_digest;
339 	u32 cur_digestsize;
340 
341 	if (!event_data->modsig)
342 		return 0;
343 
344 	if (event_data->violation) {
345 		/* Recording a violation. */
346 		hash_algo = HASH_ALGO_SHA1;
347 		cur_digest = NULL;
348 		cur_digestsize = 0;
349 	} else {
350 		int rc;
351 
352 		rc = ima_get_modsig_digest(event_data->modsig, &hash_algo,
353 					   &cur_digest, &cur_digestsize);
354 		if (rc)
355 			return rc;
356 		else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0)
357 			/* There was some error collecting the digest. */
358 			return -EINVAL;
359 	}
360 
361 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
362 					   hash_algo, field_data);
363 }
364 
365 static int ima_eventname_init_common(struct ima_event_data *event_data,
366 				     struct ima_field_data *field_data,
367 				     bool size_limit)
368 {
369 	const char *cur_filename = NULL;
370 	u32 cur_filename_len = 0;
371 
372 	BUG_ON(event_data->filename == NULL && event_data->file == NULL);
373 
374 	if (event_data->filename) {
375 		cur_filename = event_data->filename;
376 		cur_filename_len = strlen(event_data->filename);
377 
378 		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
379 			goto out;
380 	}
381 
382 	if (event_data->file) {
383 		cur_filename = event_data->file->f_path.dentry->d_name.name;
384 		cur_filename_len = strlen(cur_filename);
385 	} else
386 		/*
387 		 * Truncate filename if the latter is too long and
388 		 * the file descriptor is not available.
389 		 */
390 		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
391 out:
392 	return ima_write_template_field_data(cur_filename, cur_filename_len,
393 					     DATA_FMT_STRING, field_data);
394 }
395 
396 /*
397  * This function writes the name of an event (with size limit).
398  */
399 int ima_eventname_init(struct ima_event_data *event_data,
400 		       struct ima_field_data *field_data)
401 {
402 	return ima_eventname_init_common(event_data, field_data, true);
403 }
404 
405 /*
406  * This function writes the name of an event (without size limit).
407  */
408 int ima_eventname_ng_init(struct ima_event_data *event_data,
409 			  struct ima_field_data *field_data)
410 {
411 	return ima_eventname_init_common(event_data, field_data, false);
412 }
413 
414 /*
415  *  ima_eventsig_init - include the file signature as part of the template data
416  */
417 int ima_eventsig_init(struct ima_event_data *event_data,
418 		      struct ima_field_data *field_data)
419 {
420 	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
421 
422 	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
423 		return 0;
424 
425 	return ima_write_template_field_data(xattr_value, event_data->xattr_len,
426 					     DATA_FMT_HEX, field_data);
427 }
428 
429 /*
430  *  ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
431  *  template data.
432  */
433 int ima_eventbuf_init(struct ima_event_data *event_data,
434 		      struct ima_field_data *field_data)
435 {
436 	if ((!event_data->buf) || (event_data->buf_len == 0))
437 		return 0;
438 
439 	return ima_write_template_field_data(event_data->buf,
440 					     event_data->buf_len, DATA_FMT_HEX,
441 					     field_data);
442 }
443 
444 /*
445  *  ima_eventmodsig_init - include the appended file signature as part of the
446  *  template data
447  */
448 int ima_eventmodsig_init(struct ima_event_data *event_data,
449 			 struct ima_field_data *field_data)
450 {
451 	const void *data;
452 	u32 data_len;
453 	int rc;
454 
455 	if (!event_data->modsig)
456 		return 0;
457 
458 	/*
459 	 * modsig is a runtime structure containing pointers. Get its raw data
460 	 * instead.
461 	 */
462 	rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len);
463 	if (rc)
464 		return rc;
465 
466 	return ima_write_template_field_data(data, data_len, DATA_FMT_HEX,
467 					     field_data);
468 }
469