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
16 enum header_fields { HDR_PCR, HDR_DIGEST, HDR_TEMPLATE_NAME,
17 HDR_TEMPLATE_DATA, HDR__LAST };
18
19 static 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
32 static LIST_HEAD(defined_templates);
33 static DEFINE_SPINLOCK(template_list);
34 static int template_setup_done;
35
36 static 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
82 static struct ima_template_desc *ima_template;
83 static 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 */
92 bool 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
104 static 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
142 static 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
163 struct 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
180 static const struct ima_template_field *
181 lookup_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
192 static 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
208 int 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
259 void 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
274 struct 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
284 struct 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
293 int __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
325 static 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);
352 out:
353 return template_desc;
354 }
355
356 static 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. */
414 int 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
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