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 goto out; 345 346 spin_lock(&template_list); 347 list_add_tail_rcu(&template_desc->list, &defined_templates); 348 spin_unlock(&template_list); 349 out: 350 return template_desc; 351 } 352 353 static int ima_restore_template_data(struct ima_template_desc *template_desc, 354 void *template_data, 355 int template_data_size, 356 struct ima_template_entry **entry) 357 { 358 struct tpm_digest *digests; 359 int ret = 0; 360 int i; 361 362 *entry = kzalloc(struct_size(*entry, template_data, 363 template_desc->num_fields), GFP_NOFS); 364 if (!*entry) 365 return -ENOMEM; 366 367 digests = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots, 368 sizeof(*digests), GFP_NOFS); 369 if (!digests) { 370 kfree(*entry); 371 return -ENOMEM; 372 } 373 374 (*entry)->digests = digests; 375 376 ret = ima_parse_buf(template_data, template_data + template_data_size, 377 NULL, template_desc->num_fields, 378 (*entry)->template_data, NULL, NULL, 379 ENFORCE_FIELDS | ENFORCE_BUFEND, "template data"); 380 if (ret < 0) { 381 kfree((*entry)->digests); 382 kfree(*entry); 383 return ret; 384 } 385 386 (*entry)->template_desc = template_desc; 387 for (i = 0; i < template_desc->num_fields; i++) { 388 struct ima_field_data *field_data = &(*entry)->template_data[i]; 389 u8 *data = field_data->data; 390 391 (*entry)->template_data[i].data = 392 kzalloc(field_data->len + 1, GFP_KERNEL); 393 if (!(*entry)->template_data[i].data) { 394 ret = -ENOMEM; 395 break; 396 } 397 memcpy((*entry)->template_data[i].data, data, field_data->len); 398 (*entry)->template_data_len += sizeof(field_data->len); 399 (*entry)->template_data_len += field_data->len; 400 } 401 402 if (ret < 0) { 403 ima_free_template_entry(*entry); 404 *entry = NULL; 405 } 406 407 return ret; 408 } 409 410 /* Restore the serialized binary measurement list without extending PCRs. */ 411 int ima_restore_measurement_list(loff_t size, void *buf) 412 { 413 char template_name[MAX_TEMPLATE_NAME_LEN]; 414 unsigned char zero[TPM_DIGEST_SIZE] = { 0 }; 415 416 struct ima_kexec_hdr *khdr = buf; 417 struct ima_field_data hdr[HDR__LAST] = { 418 [HDR_PCR] = {.len = sizeof(u32)}, 419 [HDR_DIGEST] = {.len = TPM_DIGEST_SIZE}, 420 }; 421 422 void *bufp = buf + sizeof(*khdr); 423 void *bufendp; 424 struct ima_template_entry *entry; 425 struct ima_template_desc *template_desc; 426 DECLARE_BITMAP(hdr_mask, HDR__LAST); 427 unsigned long count = 0; 428 int ret = 0; 429 430 if (!buf || size < sizeof(*khdr)) 431 return 0; 432 433 if (ima_canonical_fmt) { 434 khdr->version = le16_to_cpu((__force __le16)khdr->version); 435 khdr->count = le64_to_cpu((__force __le64)khdr->count); 436 khdr->buffer_size = le64_to_cpu((__force __le64)khdr->buffer_size); 437 } 438 439 if (khdr->version != 1) { 440 pr_err("attempting to restore a incompatible measurement list"); 441 return -EINVAL; 442 } 443 444 if (khdr->count > ULONG_MAX - 1) { 445 pr_err("attempting to restore too many measurements"); 446 return -EINVAL; 447 } 448 449 bitmap_zero(hdr_mask, HDR__LAST); 450 bitmap_set(hdr_mask, HDR_PCR, 1); 451 bitmap_set(hdr_mask, HDR_DIGEST, 1); 452 453 /* 454 * ima kexec buffer prefix: version, buffer size, count 455 * v1 format: pcr, digest, template-name-len, template-name, 456 * template-data-size, template-data 457 */ 458 bufendp = buf + khdr->buffer_size; 459 while ((bufp < bufendp) && (count++ < khdr->count)) { 460 int enforce_mask = ENFORCE_FIELDS; 461 462 enforce_mask |= (count == khdr->count) ? ENFORCE_BUFEND : 0; 463 ret = ima_parse_buf(bufp, bufendp, &bufp, HDR__LAST, hdr, NULL, 464 hdr_mask, enforce_mask, "entry header"); 465 if (ret < 0) 466 break; 467 468 if (hdr[HDR_TEMPLATE_NAME].len >= MAX_TEMPLATE_NAME_LEN) { 469 pr_err("attempting to restore a template name that is too long\n"); 470 ret = -EINVAL; 471 break; 472 } 473 474 /* template name is not null terminated */ 475 memcpy(template_name, hdr[HDR_TEMPLATE_NAME].data, 476 hdr[HDR_TEMPLATE_NAME].len); 477 template_name[hdr[HDR_TEMPLATE_NAME].len] = 0; 478 479 if (strcmp(template_name, "ima") == 0) { 480 pr_err("attempting to restore an unsupported template \"%s\" failed\n", 481 template_name); 482 ret = -EINVAL; 483 break; 484 } 485 486 template_desc = lookup_template_desc(template_name); 487 if (!template_desc) { 488 template_desc = restore_template_fmt(template_name); 489 if (!template_desc) 490 break; 491 } 492 493 /* 494 * Only the running system's template format is initialized 495 * on boot. As needed, initialize the other template formats. 496 */ 497 ret = template_desc_init_fields(template_desc->fmt, 498 &(template_desc->fields), 499 &(template_desc->num_fields)); 500 if (ret < 0) { 501 pr_err("attempting to restore the template fmt \"%s\" failed\n", 502 template_desc->fmt); 503 ret = -EINVAL; 504 break; 505 } 506 507 ret = ima_restore_template_data(template_desc, 508 hdr[HDR_TEMPLATE_DATA].data, 509 hdr[HDR_TEMPLATE_DATA].len, 510 &entry); 511 if (ret < 0) 512 break; 513 514 if (memcmp(hdr[HDR_DIGEST].data, zero, sizeof(zero))) { 515 ret = ima_calc_field_array_hash( 516 &entry->template_data[0], 517 entry); 518 if (ret < 0) { 519 pr_err("cannot calculate template digest\n"); 520 ret = -EINVAL; 521 break; 522 } 523 } 524 525 entry->pcr = !ima_canonical_fmt ? *(u32 *)(hdr[HDR_PCR].data) : 526 le32_to_cpu(*(__le32 *)(hdr[HDR_PCR].data)); 527 ret = ima_restore_measurement_entry(entry); 528 if (ret < 0) 529 break; 530 531 } 532 return ret; 533 } 534