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.c
9 *      Helpers to manage template descriptors.
10 */
11
12#include <linux/rculist.h>
13#include "ima.h"
14#include "ima_template_lib.h"
15
16enum header_fields { HDR_PCR, HDR_DIGEST, HDR_TEMPLATE_NAME,
17		     HDR_TEMPLATE_DATA, HDR__LAST };
18
19static struct ima_template_desc builtin_templates[] = {
20	{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
21	{.name = "ima-ng", .fmt = "d-ng|n-ng"},
22	{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
23	{.name = "ima-ngv2", .fmt = "d-ngv2|n-ng"},
24	{.name = "ima-sigv2", .fmt = "d-ngv2|n-ng|sig"},
25	{.name = "ima-buf", .fmt = "d-ng|n-ng|buf"},
26	{.name = "ima-modsig", .fmt = "d-ng|n-ng|sig|d-modsig|modsig"},
27	{.name = "evm-sig",
28	 .fmt = "d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode"},
29	{.name = "", .fmt = ""},	/* placeholder for a custom format */
30};
31
32static LIST_HEAD(defined_templates);
33static DEFINE_SPINLOCK(template_list);
34static int template_setup_done;
35
36static const struct ima_template_field supported_fields[] = {
37	{.field_id = "d", .field_init = ima_eventdigest_init,
38	 .field_show = ima_show_template_digest},
39	{.field_id = "n", .field_init = ima_eventname_init,
40	 .field_show = ima_show_template_string},
41	{.field_id = "d-ng", .field_init = ima_eventdigest_ng_init,
42	 .field_show = ima_show_template_digest_ng},
43	{.field_id = "d-ngv2", .field_init = ima_eventdigest_ngv2_init,
44	 .field_show = ima_show_template_digest_ngv2},
45	{.field_id = "n-ng", .field_init = ima_eventname_ng_init,
46	 .field_show = ima_show_template_string},
47	{.field_id = "sig", .field_init = ima_eventsig_init,
48	 .field_show = ima_show_template_sig},
49	{.field_id = "buf", .field_init = ima_eventbuf_init,
50	 .field_show = ima_show_template_buf},
51	{.field_id = "d-modsig", .field_init = ima_eventdigest_modsig_init,
52	 .field_show = ima_show_template_digest_ng},
53	{.field_id = "modsig", .field_init = ima_eventmodsig_init,
54	 .field_show = ima_show_template_sig},
55	{.field_id = "evmsig", .field_init = ima_eventevmsig_init,
56	 .field_show = ima_show_template_sig},
57	{.field_id = "iuid", .field_init = ima_eventinodeuid_init,
58	 .field_show = ima_show_template_uint},
59	{.field_id = "igid", .field_init = ima_eventinodegid_init,
60	 .field_show = ima_show_template_uint},
61	{.field_id = "imode", .field_init = ima_eventinodemode_init,
62	 .field_show = ima_show_template_uint},
63	{.field_id = "xattrnames",
64	 .field_init = ima_eventinodexattrnames_init,
65	 .field_show = ima_show_template_string},
66	{.field_id = "xattrlengths",
67	 .field_init = ima_eventinodexattrlengths_init,
68	 .field_show = ima_show_template_sig},
69	{.field_id = "xattrvalues",
70	 .field_init = ima_eventinodexattrvalues_init,
71	 .field_show = ima_show_template_sig},
72};
73
74/*
75 * Used when restoring measurements carried over from a kexec. 'd' and 'n' don't
76 * need to be accounted for since they shouldn't be defined in the same template
77 * description as 'd-ng' and 'n-ng' respectively.
78 */
79#define MAX_TEMPLATE_NAME_LEN \
80	sizeof("d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode")
81
82static struct ima_template_desc *ima_template;
83static struct ima_template_desc *ima_buf_template;
84
85/**
86 * ima_template_has_modsig - Check whether template has modsig-related fields.
87 * @ima_template: IMA template to check.
88 *
89 * Tells whether the given template has fields referencing a file's appended
90 * signature.
91 */
92bool ima_template_has_modsig(const struct ima_template_desc *ima_template)
93{
94	int i;
95
96	for (i = 0; i < ima_template->num_fields; i++)
97		if (!strcmp(ima_template->fields[i]->field_id, "modsig") ||
98		    !strcmp(ima_template->fields[i]->field_id, "d-modsig"))
99			return true;
100
101	return false;
102}
103
104static int __init ima_template_setup(char *str)
105{
106	struct ima_template_desc *template_desc;
107	int template_len = strlen(str);
108
109	if (template_setup_done)
110		return 1;
111
112	if (!ima_template)
113		ima_init_template_list();
114
115	/*
116	 * Verify that a template with the supplied name exists.
117	 * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
118	 */
119	template_desc = lookup_template_desc(str);
120	if (!template_desc) {
121		pr_err("template %s not found, using %s\n",
122		       str, CONFIG_IMA_DEFAULT_TEMPLATE);
123		return 1;
124	}
125
126	/*
127	 * Verify whether the current hash algorithm is supported
128	 * by the 'ima' template.
129	 */
130	if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
131	    ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
132		pr_err("template does not support hash alg\n");
133		return 1;
134	}
135
136	ima_template = template_desc;
137	template_setup_done = 1;
138	return 1;
139}
140__setup("ima_template=", ima_template_setup);
141
142static int __init ima_template_fmt_setup(char *str)
143{
144	int num_templates = ARRAY_SIZE(builtin_templates);
145
146	if (template_setup_done)
147		return 1;
148
149	if (template_desc_init_fields(str, NULL, NULL) < 0) {
150		pr_err("format string '%s' not valid, using template %s\n",
151		       str, CONFIG_IMA_DEFAULT_TEMPLATE);
152		return 1;
153	}
154
155	builtin_templates[num_templates - 1].fmt = str;
156	ima_template = builtin_templates + num_templates - 1;
157	template_setup_done = 1;
158
159	return 1;
160}
161__setup("ima_template_fmt=", ima_template_fmt_setup);
162
163struct ima_template_desc *lookup_template_desc(const char *name)
164{
165	struct ima_template_desc *template_desc;
166	int found = 0;
167
168	rcu_read_lock();
169	list_for_each_entry_rcu(template_desc, &defined_templates, list) {
170		if ((strcmp(template_desc->name, name) == 0) ||
171		    (strcmp(template_desc->fmt, name) == 0)) {
172			found = 1;
173			break;
174		}
175	}
176	rcu_read_unlock();
177	return found ? template_desc : NULL;
178}
179
180static const struct ima_template_field *
181lookup_template_field(const char *field_id)
182{
183	int i;
184
185	for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
186		if (strncmp(supported_fields[i].field_id, field_id,
187			    IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
188			return &supported_fields[i];
189	return NULL;
190}
191
192static int template_fmt_size(const char *template_fmt)
193{
194	char c;
195	int template_fmt_len = strlen(template_fmt);
196	int i = 0, j = 0;
197
198	while (i < template_fmt_len) {
199		c = template_fmt[i];
200		if (c == '|')
201			j++;
202		i++;
203	}
204
205	return j + 1;
206}
207
208int template_desc_init_fields(const char *template_fmt,
209			      const struct ima_template_field ***fields,
210			      int *num_fields)
211{
212	const char *template_fmt_ptr;
213	const struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX];
214	int template_num_fields;
215	int i, len;
216
217	if (num_fields && *num_fields > 0) /* already initialized? */
218		return 0;
219
220	template_num_fields = template_fmt_size(template_fmt);
221
222	if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
223		pr_err("format string '%s' contains too many fields\n",
224		       template_fmt);
225		return -EINVAL;
226	}
227
228	for (i = 0, template_fmt_ptr = template_fmt; i < template_num_fields;
229	     i++, template_fmt_ptr += len + 1) {
230		char tmp_field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN + 1];
231
232		len = strchrnul(template_fmt_ptr, '|') - template_fmt_ptr;
233		if (len == 0 || len > IMA_TEMPLATE_FIELD_ID_MAX_LEN) {
234			pr_err("Invalid field with length %d\n", len);
235			return -EINVAL;
236		}
237
238		memcpy(tmp_field_id, template_fmt_ptr, len);
239		tmp_field_id[len] = '\0';
240		found_fields[i] = lookup_template_field(tmp_field_id);
241		if (!found_fields[i]) {
242			pr_err("field '%s' not found\n", tmp_field_id);
243			return -ENOENT;
244		}
245	}
246
247	if (fields && num_fields) {
248		*fields = kmalloc_array(i, sizeof(**fields), GFP_KERNEL);
249		if (*fields == NULL)
250			return -ENOMEM;
251
252		memcpy(*fields, found_fields, i * sizeof(**fields));
253		*num_fields = i;
254	}
255
256	return 0;
257}
258
259void ima_init_template_list(void)
260{
261	int i;
262
263	if (!list_empty(&defined_templates))
264		return;
265
266	spin_lock(&template_list);
267	for (i = 0; i < ARRAY_SIZE(builtin_templates); i++) {
268		list_add_tail_rcu(&builtin_templates[i].list,
269				  &defined_templates);
270	}
271	spin_unlock(&template_list);
272}
273
274struct ima_template_desc *ima_template_desc_current(void)
275{
276	if (!ima_template) {
277		ima_init_template_list();
278		ima_template =
279		    lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
280	}
281	return ima_template;
282}
283
284struct ima_template_desc *ima_template_desc_buf(void)
285{
286	if (!ima_buf_template) {
287		ima_init_template_list();
288		ima_buf_template = lookup_template_desc("ima-buf");
289	}
290	return ima_buf_template;
291}
292
293int __init ima_init_template(void)
294{
295	struct ima_template_desc *template = ima_template_desc_current();
296	int result;
297
298	result = template_desc_init_fields(template->fmt,
299					   &(template->fields),
300					   &(template->num_fields));
301	if (result < 0) {
302		pr_err("template %s init failed, result: %d\n",
303		       (strlen(template->name) ?
304		       template->name : template->fmt), result);
305		return result;
306	}
307
308	template = ima_template_desc_buf();
309	if (!template) {
310		pr_err("Failed to get ima-buf template\n");
311		return -EINVAL;
312	}
313
314	result = template_desc_init_fields(template->fmt,
315					   &(template->fields),
316					   &(template->num_fields));
317	if (result < 0)
318		pr_err("template %s init failed, result: %d\n",
319		       (strlen(template->name) ?
320		       template->name : template->fmt), result);
321
322	return result;
323}
324
325static struct ima_template_desc *restore_template_fmt(char *template_name)
326{
327	struct ima_template_desc *template_desc = NULL;
328	int ret;
329
330	ret = template_desc_init_fields(template_name, NULL, NULL);
331	if (ret < 0) {
332		pr_err("attempting to initialize the template \"%s\" failed\n",
333			template_name);
334		goto out;
335	}
336
337	template_desc = kzalloc(sizeof(*template_desc), GFP_KERNEL);
338	if (!template_desc)
339		goto out;
340
341	template_desc->name = "";
342	template_desc->fmt = kstrdup(template_name, GFP_KERNEL);
343	if (!template_desc->fmt) {
344		kfree(template_desc);
345		template_desc = NULL;
346		goto out;
347	}
348
349	spin_lock(&template_list);
350	list_add_tail_rcu(&template_desc->list, &defined_templates);
351	spin_unlock(&template_list);
352out:
353	return template_desc;
354}
355
356static int ima_restore_template_data(struct ima_template_desc *template_desc,
357				     void *template_data,
358				     int template_data_size,
359				     struct ima_template_entry **entry)
360{
361	struct tpm_digest *digests;
362	int ret = 0;
363	int i;
364
365	*entry = kzalloc(struct_size(*entry, template_data,
366				     template_desc->num_fields), GFP_NOFS);
367	if (!*entry)
368		return -ENOMEM;
369
370	digests = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots,
371			  sizeof(*digests), GFP_NOFS);
372	if (!digests) {
373		kfree(*entry);
374		return -ENOMEM;
375	}
376
377	(*entry)->digests = digests;
378
379	ret = ima_parse_buf(template_data, template_data + template_data_size,
380			    NULL, template_desc->num_fields,
381			    (*entry)->template_data, NULL, NULL,
382			    ENFORCE_FIELDS | ENFORCE_BUFEND, "template data");
383	if (ret < 0) {
384		kfree((*entry)->digests);
385		kfree(*entry);
386		return ret;
387	}
388
389	(*entry)->template_desc = template_desc;
390	for (i = 0; i < template_desc->num_fields; i++) {
391		struct ima_field_data *field_data = &(*entry)->template_data[i];
392		u8 *data = field_data->data;
393
394		(*entry)->template_data[i].data =
395			kzalloc(field_data->len + 1, GFP_KERNEL);
396		if (!(*entry)->template_data[i].data) {
397			ret = -ENOMEM;
398			break;
399		}
400		memcpy((*entry)->template_data[i].data, data, field_data->len);
401		(*entry)->template_data_len += sizeof(field_data->len);
402		(*entry)->template_data_len += field_data->len;
403	}
404
405	if (ret < 0) {
406		ima_free_template_entry(*entry);
407		*entry = NULL;
408	}
409
410	return ret;
411}
412
413/* Restore the serialized binary measurement list without extending PCRs. */
414int ima_restore_measurement_list(loff_t size, void *buf)
415{
416	char template_name[MAX_TEMPLATE_NAME_LEN];
417	unsigned char zero[TPM_DIGEST_SIZE] = { 0 };
418
419	struct ima_kexec_hdr *khdr = buf;
420	struct ima_field_data hdr[HDR__LAST] = {
421		[HDR_PCR] = {.len = sizeof(u32)},
422		[HDR_DIGEST] = {.len = TPM_DIGEST_SIZE},
423	};
424
425	void *bufp = buf + sizeof(*khdr);
426	void *bufendp;
427	struct ima_template_entry *entry;
428	struct ima_template_desc *template_desc;
429	DECLARE_BITMAP(hdr_mask, HDR__LAST);
430	unsigned long count = 0;
431	int ret = 0;
432
433	if (!buf || size < sizeof(*khdr))
434		return 0;
435
436	if (ima_canonical_fmt) {
437		khdr->version = le16_to_cpu((__force __le16)khdr->version);
438		khdr->count = le64_to_cpu((__force __le64)khdr->count);
439		khdr->buffer_size = le64_to_cpu((__force __le64)khdr->buffer_size);
440	}
441
442	if (khdr->version != 1) {
443		pr_err("attempting to restore a incompatible measurement list");
444		return -EINVAL;
445	}
446
447	if (khdr->count > ULONG_MAX - 1) {
448		pr_err("attempting to restore too many measurements");
449		return -EINVAL;
450	}
451
452	bitmap_zero(hdr_mask, HDR__LAST);
453	bitmap_set(hdr_mask, HDR_PCR, 1);
454	bitmap_set(hdr_mask, HDR_DIGEST, 1);
455
456	/*
457	 * ima kexec buffer prefix: version, buffer size, count
458	 * v1 format: pcr, digest, template-name-len, template-name,
459	 *	      template-data-size, template-data
460	 */
461	bufendp = buf + khdr->buffer_size;
462	while ((bufp < bufendp) && (count++ < khdr->count)) {
463		int enforce_mask = ENFORCE_FIELDS;
464
465		enforce_mask |= (count == khdr->count) ? ENFORCE_BUFEND : 0;
466		ret = ima_parse_buf(bufp, bufendp, &bufp, HDR__LAST, hdr, NULL,
467				    hdr_mask, enforce_mask, "entry header");
468		if (ret < 0)
469			break;
470
471		if (hdr[HDR_TEMPLATE_NAME].len >= MAX_TEMPLATE_NAME_LEN) {
472			pr_err("attempting to restore a template name that is too long\n");
473			ret = -EINVAL;
474			break;
475		}
476
477		/* template name is not null terminated */
478		memcpy(template_name, hdr[HDR_TEMPLATE_NAME].data,
479		       hdr[HDR_TEMPLATE_NAME].len);
480		template_name[hdr[HDR_TEMPLATE_NAME].len] = 0;
481
482		if (strcmp(template_name, "ima") == 0) {
483			pr_err("attempting to restore an unsupported template \"%s\" failed\n",
484			       template_name);
485			ret = -EINVAL;
486			break;
487		}
488
489		template_desc = lookup_template_desc(template_name);
490		if (!template_desc) {
491			template_desc = restore_template_fmt(template_name);
492			if (!template_desc)
493				break;
494		}
495
496		/*
497		 * Only the running system's template format is initialized
498		 * on boot.  As needed, initialize the other template formats.
499		 */
500		ret = template_desc_init_fields(template_desc->fmt,
501						&(template_desc->fields),
502						&(template_desc->num_fields));
503		if (ret < 0) {
504			pr_err("attempting to restore the template fmt \"%s\" failed\n",
505			       template_desc->fmt);
506			ret = -EINVAL;
507			break;
508		}
509
510		ret = ima_restore_template_data(template_desc,
511						hdr[HDR_TEMPLATE_DATA].data,
512						hdr[HDR_TEMPLATE_DATA].len,
513						&entry);
514		if (ret < 0)
515			break;
516
517		if (memcmp(hdr[HDR_DIGEST].data, zero, sizeof(zero))) {
518			ret = ima_calc_field_array_hash(
519						&entry->template_data[0],
520						entry);
521			if (ret < 0) {
522				pr_err("cannot calculate template digest\n");
523				ret = -EINVAL;
524				break;
525			}
526		}
527
528		entry->pcr = !ima_canonical_fmt ? *(u32 *)(hdr[HDR_PCR].data) :
529			     le32_to_cpu(*(__le32 *)(hdr[HDR_PCR].data));
530		ret = ima_restore_measurement_entry(entry);
531		if (ret < 0)
532			break;
533
534	}
535	return ret;
536}
537