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