1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 4 * 5 * Authors: 6 * Kylene Hall <kjhall@us.ibm.com> 7 * Reiner Sailer <sailer@us.ibm.com> 8 * Mimi Zohar <zohar@us.ibm.com> 9 * 10 * File: ima_fs.c 11 * implemenents security file system for reporting 12 * current measurement list and IMA statistics 13 */ 14 15 #include <linux/fcntl.h> 16 #include <linux/kernel_read_file.h> 17 #include <linux/slab.h> 18 #include <linux/init.h> 19 #include <linux/seq_file.h> 20 #include <linux/rculist.h> 21 #include <linux/rcupdate.h> 22 #include <linux/parser.h> 23 #include <linux/vmalloc.h> 24 25 #include "ima.h" 26 27 static DEFINE_MUTEX(ima_write_mutex); 28 29 bool ima_canonical_fmt; 30 static int __init default_canonical_fmt_setup(char *str) 31 { 32 #ifdef __BIG_ENDIAN 33 ima_canonical_fmt = true; 34 #endif 35 return 1; 36 } 37 __setup("ima_canonical_fmt", default_canonical_fmt_setup); 38 39 static int valid_policy = 1; 40 41 static ssize_t ima_show_htable_value(char __user *buf, size_t count, 42 loff_t *ppos, atomic_long_t *val) 43 { 44 char tmpbuf[32]; /* greater than largest 'long' string value */ 45 ssize_t len; 46 47 len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", atomic_long_read(val)); 48 return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); 49 } 50 51 static ssize_t ima_show_htable_violations(struct file *filp, 52 char __user *buf, 53 size_t count, loff_t *ppos) 54 { 55 return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); 56 } 57 58 static const struct file_operations ima_htable_violations_ops = { 59 .read = ima_show_htable_violations, 60 .llseek = generic_file_llseek, 61 }; 62 63 static ssize_t ima_show_measurements_count(struct file *filp, 64 char __user *buf, 65 size_t count, loff_t *ppos) 66 { 67 return ima_show_htable_value(buf, count, ppos, &ima_htable.len); 68 69 } 70 71 static const struct file_operations ima_measurements_count_ops = { 72 .read = ima_show_measurements_count, 73 .llseek = generic_file_llseek, 74 }; 75 76 /* returns pointer to hlist_node */ 77 static void *ima_measurements_start(struct seq_file *m, loff_t *pos) 78 { 79 loff_t l = *pos; 80 struct ima_queue_entry *qe; 81 82 /* we need a lock since pos could point beyond last element */ 83 rcu_read_lock(); 84 list_for_each_entry_rcu(qe, &ima_measurements, later) { 85 if (!l--) { 86 rcu_read_unlock(); 87 return qe; 88 } 89 } 90 rcu_read_unlock(); 91 return NULL; 92 } 93 94 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) 95 { 96 struct ima_queue_entry *qe = v; 97 98 /* lock protects when reading beyond last element 99 * against concurrent list-extension 100 */ 101 rcu_read_lock(); 102 qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later); 103 rcu_read_unlock(); 104 (*pos)++; 105 106 return (&qe->later == &ima_measurements) ? NULL : qe; 107 } 108 109 static void ima_measurements_stop(struct seq_file *m, void *v) 110 { 111 } 112 113 void ima_putc(struct seq_file *m, void *data, int datalen) 114 { 115 while (datalen--) 116 seq_putc(m, *(char *)data++); 117 } 118 119 /* print format: 120 * 32bit-le=pcr# 121 * char[20]=template digest 122 * 32bit-le=template name size 123 * char[n]=template name 124 * [eventdata length] 125 * eventdata[n]=template specific data 126 */ 127 int ima_measurements_show(struct seq_file *m, void *v) 128 { 129 /* the list never shrinks, so we don't need a lock here */ 130 struct ima_queue_entry *qe = v; 131 struct ima_template_entry *e; 132 char *template_name; 133 u32 pcr, namelen, template_data_len; /* temporary fields */ 134 bool is_ima_template = false; 135 int i; 136 137 /* get entry */ 138 e = qe->entry; 139 if (e == NULL) 140 return -1; 141 142 template_name = (e->template_desc->name[0] != '\0') ? 143 e->template_desc->name : e->template_desc->fmt; 144 145 /* 146 * 1st: PCRIndex 147 * PCR used defaults to the same (config option) in 148 * little-endian format, unless set in policy 149 */ 150 pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr); 151 ima_putc(m, &pcr, sizeof(e->pcr)); 152 153 /* 2nd: template digest */ 154 ima_putc(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE); 155 156 /* 3rd: template name size */ 157 namelen = !ima_canonical_fmt ? strlen(template_name) : 158 cpu_to_le32(strlen(template_name)); 159 ima_putc(m, &namelen, sizeof(namelen)); 160 161 /* 4th: template name */ 162 ima_putc(m, template_name, strlen(template_name)); 163 164 /* 5th: template length (except for 'ima' template) */ 165 if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0) 166 is_ima_template = true; 167 168 if (!is_ima_template) { 169 template_data_len = !ima_canonical_fmt ? e->template_data_len : 170 cpu_to_le32(e->template_data_len); 171 ima_putc(m, &template_data_len, sizeof(e->template_data_len)); 172 } 173 174 /* 6th: template specific data */ 175 for (i = 0; i < e->template_desc->num_fields; i++) { 176 enum ima_show_type show = IMA_SHOW_BINARY; 177 const struct ima_template_field *field = 178 e->template_desc->fields[i]; 179 180 if (is_ima_template && strcmp(field->field_id, "d") == 0) 181 show = IMA_SHOW_BINARY_NO_FIELD_LEN; 182 if (is_ima_template && strcmp(field->field_id, "n") == 0) 183 show = IMA_SHOW_BINARY_OLD_STRING_FMT; 184 field->field_show(m, show, &e->template_data[i]); 185 } 186 return 0; 187 } 188 189 static const struct seq_operations ima_measurments_seqops = { 190 .start = ima_measurements_start, 191 .next = ima_measurements_next, 192 .stop = ima_measurements_stop, 193 .show = ima_measurements_show 194 }; 195 196 static int ima_measurements_open(struct inode *inode, struct file *file) 197 { 198 return seq_open(file, &ima_measurments_seqops); 199 } 200 201 static const struct file_operations ima_measurements_ops = { 202 .open = ima_measurements_open, 203 .read = seq_read, 204 .llseek = seq_lseek, 205 .release = seq_release, 206 }; 207 208 void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) 209 { 210 u32 i; 211 212 for (i = 0; i < size; i++) 213 seq_printf(m, "%02x", *(digest + i)); 214 } 215 216 /* print in ascii */ 217 static int ima_ascii_measurements_show(struct seq_file *m, void *v) 218 { 219 /* the list never shrinks, so we don't need a lock here */ 220 struct ima_queue_entry *qe = v; 221 struct ima_template_entry *e; 222 char *template_name; 223 int i; 224 225 /* get entry */ 226 e = qe->entry; 227 if (e == NULL) 228 return -1; 229 230 template_name = (e->template_desc->name[0] != '\0') ? 231 e->template_desc->name : e->template_desc->fmt; 232 233 /* 1st: PCR used (config option) */ 234 seq_printf(m, "%2d ", e->pcr); 235 236 /* 2nd: SHA1 template hash */ 237 ima_print_digest(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE); 238 239 /* 3th: template name */ 240 seq_printf(m, " %s", template_name); 241 242 /* 4th: template specific data */ 243 for (i = 0; i < e->template_desc->num_fields; i++) { 244 seq_puts(m, " "); 245 if (e->template_data[i].len == 0) 246 continue; 247 248 e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII, 249 &e->template_data[i]); 250 } 251 seq_puts(m, "\n"); 252 return 0; 253 } 254 255 static const struct seq_operations ima_ascii_measurements_seqops = { 256 .start = ima_measurements_start, 257 .next = ima_measurements_next, 258 .stop = ima_measurements_stop, 259 .show = ima_ascii_measurements_show 260 }; 261 262 static int ima_ascii_measurements_open(struct inode *inode, struct file *file) 263 { 264 return seq_open(file, &ima_ascii_measurements_seqops); 265 } 266 267 static const struct file_operations ima_ascii_measurements_ops = { 268 .open = ima_ascii_measurements_open, 269 .read = seq_read, 270 .llseek = seq_lseek, 271 .release = seq_release, 272 }; 273 274 static ssize_t ima_read_policy(char *path) 275 { 276 void *data = NULL; 277 char *datap; 278 size_t size; 279 int rc, pathlen = strlen(path); 280 281 char *p; 282 283 /* remove \n */ 284 datap = path; 285 strsep(&datap, "\n"); 286 287 rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL, 288 READING_POLICY); 289 if (rc < 0) { 290 pr_err("Unable to open file: %s (%d)", path, rc); 291 return rc; 292 } 293 size = rc; 294 rc = 0; 295 296 datap = data; 297 while (size > 0 && (p = strsep(&datap, "\n"))) { 298 pr_debug("rule: %s\n", p); 299 rc = ima_parse_add_rule(p); 300 if (rc < 0) 301 break; 302 size -= rc; 303 } 304 305 vfree(data); 306 if (rc < 0) 307 return rc; 308 else if (size) 309 return -EINVAL; 310 else 311 return pathlen; 312 } 313 314 static ssize_t ima_write_policy(struct file *file, const char __user *buf, 315 size_t datalen, loff_t *ppos) 316 { 317 char *data; 318 ssize_t result; 319 320 if (datalen >= PAGE_SIZE) 321 datalen = PAGE_SIZE - 1; 322 323 /* No partial writes. */ 324 result = -EINVAL; 325 if (*ppos != 0) 326 goto out; 327 328 data = memdup_user_nul(buf, datalen); 329 if (IS_ERR(data)) { 330 result = PTR_ERR(data); 331 goto out; 332 } 333 334 result = mutex_lock_interruptible(&ima_write_mutex); 335 if (result < 0) 336 goto out_free; 337 338 if (data[0] == '/') { 339 result = ima_read_policy(data); 340 } else if (ima_appraise & IMA_APPRAISE_POLICY) { 341 pr_err("signed policy file (specified as an absolute pathname) required\n"); 342 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, 343 "policy_update", "signed policy required", 344 1, 0); 345 result = -EACCES; 346 } else { 347 result = ima_parse_add_rule(data); 348 } 349 mutex_unlock(&ima_write_mutex); 350 out_free: 351 kfree(data); 352 out: 353 if (result < 0) 354 valid_policy = 0; 355 356 return result; 357 } 358 359 static struct dentry *ima_dir; 360 static struct dentry *ima_symlink; 361 static struct dentry *binary_runtime_measurements; 362 static struct dentry *ascii_runtime_measurements; 363 static struct dentry *runtime_measurements_count; 364 static struct dentry *violations; 365 static struct dentry *ima_policy; 366 367 enum ima_fs_flags { 368 IMA_FS_BUSY, 369 }; 370 371 static unsigned long ima_fs_flags; 372 373 #ifdef CONFIG_IMA_READ_POLICY 374 static const struct seq_operations ima_policy_seqops = { 375 .start = ima_policy_start, 376 .next = ima_policy_next, 377 .stop = ima_policy_stop, 378 .show = ima_policy_show, 379 }; 380 #endif 381 382 /* 383 * ima_open_policy: sequentialize access to the policy file 384 */ 385 static int ima_open_policy(struct inode *inode, struct file *filp) 386 { 387 if (!(filp->f_flags & O_WRONLY)) { 388 #ifndef CONFIG_IMA_READ_POLICY 389 return -EACCES; 390 #else 391 if ((filp->f_flags & O_ACCMODE) != O_RDONLY) 392 return -EACCES; 393 if (!capable(CAP_SYS_ADMIN)) 394 return -EPERM; 395 return seq_open(filp, &ima_policy_seqops); 396 #endif 397 } 398 if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags)) 399 return -EBUSY; 400 return 0; 401 } 402 403 /* 404 * ima_release_policy - start using the new measure policy rules. 405 * 406 * Initially, ima_measure points to the default policy rules, now 407 * point to the new policy rules, and remove the securityfs policy file, 408 * assuming a valid policy. 409 */ 410 static int ima_release_policy(struct inode *inode, struct file *file) 411 { 412 const char *cause = valid_policy ? "completed" : "failed"; 413 414 if ((file->f_flags & O_ACCMODE) == O_RDONLY) 415 return seq_release(inode, file); 416 417 if (valid_policy && ima_check_policy() < 0) { 418 cause = "failed"; 419 valid_policy = 0; 420 } 421 422 pr_info("policy update %s\n", cause); 423 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, 424 "policy_update", cause, !valid_policy, 0); 425 426 if (!valid_policy) { 427 ima_delete_rules(); 428 valid_policy = 1; 429 clear_bit(IMA_FS_BUSY, &ima_fs_flags); 430 return 0; 431 } 432 433 ima_update_policy(); 434 #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY) 435 securityfs_remove(ima_policy); 436 ima_policy = NULL; 437 #elif defined(CONFIG_IMA_WRITE_POLICY) 438 clear_bit(IMA_FS_BUSY, &ima_fs_flags); 439 #elif defined(CONFIG_IMA_READ_POLICY) 440 inode->i_mode &= ~S_IWUSR; 441 #endif 442 return 0; 443 } 444 445 static const struct file_operations ima_measure_policy_ops = { 446 .open = ima_open_policy, 447 .write = ima_write_policy, 448 .read = seq_read, 449 .release = ima_release_policy, 450 .llseek = generic_file_llseek, 451 }; 452 453 int __init ima_fs_init(void) 454 { 455 ima_dir = securityfs_create_dir("ima", integrity_dir); 456 if (IS_ERR(ima_dir)) 457 return -1; 458 459 ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima", 460 NULL); 461 if (IS_ERR(ima_symlink)) 462 goto out; 463 464 binary_runtime_measurements = 465 securityfs_create_file("binary_runtime_measurements", 466 S_IRUSR | S_IRGRP, ima_dir, NULL, 467 &ima_measurements_ops); 468 if (IS_ERR(binary_runtime_measurements)) 469 goto out; 470 471 ascii_runtime_measurements = 472 securityfs_create_file("ascii_runtime_measurements", 473 S_IRUSR | S_IRGRP, ima_dir, NULL, 474 &ima_ascii_measurements_ops); 475 if (IS_ERR(ascii_runtime_measurements)) 476 goto out; 477 478 runtime_measurements_count = 479 securityfs_create_file("runtime_measurements_count", 480 S_IRUSR | S_IRGRP, ima_dir, NULL, 481 &ima_measurements_count_ops); 482 if (IS_ERR(runtime_measurements_count)) 483 goto out; 484 485 violations = 486 securityfs_create_file("violations", S_IRUSR | S_IRGRP, 487 ima_dir, NULL, &ima_htable_violations_ops); 488 if (IS_ERR(violations)) 489 goto out; 490 491 ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS, 492 ima_dir, NULL, 493 &ima_measure_policy_ops); 494 if (IS_ERR(ima_policy)) 495 goto out; 496 497 return 0; 498 out: 499 securityfs_remove(violations); 500 securityfs_remove(runtime_measurements_count); 501 securityfs_remove(ascii_runtime_measurements); 502 securityfs_remove(binary_runtime_measurements); 503 securityfs_remove(ima_symlink); 504 securityfs_remove(ima_dir); 505 securityfs_remove(ima_policy); 506 return -1; 507 } 508