1 /* 2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 3 * 4 * Authors: 5 * Kylene Hall <kjhall@us.ibm.com> 6 * Reiner Sailer <sailer@us.ibm.com> 7 * Mimi Zohar <zohar@us.ibm.com> 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License as 11 * published by the Free Software Foundation, version 2 of the 12 * License. 13 * 14 * File: ima_fs.c 15 * implemenents security file system for reporting 16 * current measurement list and IMA statistics 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/fcntl.h> 22 #include <linux/slab.h> 23 #include <linux/init.h> 24 #include <linux/seq_file.h> 25 #include <linux/rculist.h> 26 #include <linux/rcupdate.h> 27 #include <linux/parser.h> 28 #include <linux/vmalloc.h> 29 30 #include "ima.h" 31 32 static DEFINE_MUTEX(ima_write_mutex); 33 34 bool ima_canonical_fmt; 35 static int __init default_canonical_fmt_setup(char *str) 36 { 37 #ifdef __BIG_ENDIAN 38 ima_canonical_fmt = true; 39 #endif 40 return 1; 41 } 42 __setup("ima_canonical_fmt", default_canonical_fmt_setup); 43 44 static int valid_policy = 1; 45 46 static ssize_t ima_show_htable_value(char __user *buf, size_t count, 47 loff_t *ppos, atomic_long_t *val) 48 { 49 char tmpbuf[32]; /* greater than largest 'long' string value */ 50 ssize_t len; 51 52 len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", atomic_long_read(val)); 53 return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); 54 } 55 56 static ssize_t ima_show_htable_violations(struct file *filp, 57 char __user *buf, 58 size_t count, loff_t *ppos) 59 { 60 return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); 61 } 62 63 static const struct file_operations ima_htable_violations_ops = { 64 .read = ima_show_htable_violations, 65 .llseek = generic_file_llseek, 66 }; 67 68 static ssize_t ima_show_measurements_count(struct file *filp, 69 char __user *buf, 70 size_t count, loff_t *ppos) 71 { 72 return ima_show_htable_value(buf, count, ppos, &ima_htable.len); 73 74 } 75 76 static const struct file_operations ima_measurements_count_ops = { 77 .read = ima_show_measurements_count, 78 .llseek = generic_file_llseek, 79 }; 80 81 /* returns pointer to hlist_node */ 82 static void *ima_measurements_start(struct seq_file *m, loff_t *pos) 83 { 84 loff_t l = *pos; 85 struct ima_queue_entry *qe; 86 87 /* we need a lock since pos could point beyond last element */ 88 rcu_read_lock(); 89 list_for_each_entry_rcu(qe, &ima_measurements, later) { 90 if (!l--) { 91 rcu_read_unlock(); 92 return qe; 93 } 94 } 95 rcu_read_unlock(); 96 return NULL; 97 } 98 99 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) 100 { 101 struct ima_queue_entry *qe = v; 102 103 /* lock protects when reading beyond last element 104 * against concurrent list-extension 105 */ 106 rcu_read_lock(); 107 qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later); 108 rcu_read_unlock(); 109 (*pos)++; 110 111 return (&qe->later == &ima_measurements) ? NULL : qe; 112 } 113 114 static void ima_measurements_stop(struct seq_file *m, void *v) 115 { 116 } 117 118 void ima_putc(struct seq_file *m, void *data, int datalen) 119 { 120 while (datalen--) 121 seq_putc(m, *(char *)data++); 122 } 123 124 /* print format: 125 * 32bit-le=pcr# 126 * char[20]=template digest 127 * 32bit-le=template name size 128 * char[n]=template name 129 * [eventdata length] 130 * eventdata[n]=template specific data 131 */ 132 int ima_measurements_show(struct seq_file *m, void *v) 133 { 134 /* the list never shrinks, so we don't need a lock here */ 135 struct ima_queue_entry *qe = v; 136 struct ima_template_entry *e; 137 char *template_name; 138 u32 pcr, namelen, template_data_len; /* temporary fields */ 139 bool is_ima_template = false; 140 int i; 141 142 /* get entry */ 143 e = qe->entry; 144 if (e == NULL) 145 return -1; 146 147 template_name = (e->template_desc->name[0] != '\0') ? 148 e->template_desc->name : e->template_desc->fmt; 149 150 /* 151 * 1st: PCRIndex 152 * PCR used defaults to the same (config option) in 153 * little-endian format, unless set in policy 154 */ 155 pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr); 156 ima_putc(m, &pcr, sizeof(e->pcr)); 157 158 /* 2nd: template digest */ 159 ima_putc(m, e->digest, TPM_DIGEST_SIZE); 160 161 /* 3rd: template name size */ 162 namelen = !ima_canonical_fmt ? strlen(template_name) : 163 cpu_to_le32(strlen(template_name)); 164 ima_putc(m, &namelen, sizeof(namelen)); 165 166 /* 4th: template name */ 167 ima_putc(m, template_name, strlen(template_name)); 168 169 /* 5th: template length (except for 'ima' template) */ 170 if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0) 171 is_ima_template = true; 172 173 if (!is_ima_template) { 174 template_data_len = !ima_canonical_fmt ? e->template_data_len : 175 cpu_to_le32(e->template_data_len); 176 ima_putc(m, &template_data_len, sizeof(e->template_data_len)); 177 } 178 179 /* 6th: template specific data */ 180 for (i = 0; i < e->template_desc->num_fields; i++) { 181 enum ima_show_type show = IMA_SHOW_BINARY; 182 const struct ima_template_field *field = 183 e->template_desc->fields[i]; 184 185 if (is_ima_template && strcmp(field->field_id, "d") == 0) 186 show = IMA_SHOW_BINARY_NO_FIELD_LEN; 187 if (is_ima_template && strcmp(field->field_id, "n") == 0) 188 show = IMA_SHOW_BINARY_OLD_STRING_FMT; 189 field->field_show(m, show, &e->template_data[i]); 190 } 191 return 0; 192 } 193 194 static const struct seq_operations ima_measurments_seqops = { 195 .start = ima_measurements_start, 196 .next = ima_measurements_next, 197 .stop = ima_measurements_stop, 198 .show = ima_measurements_show 199 }; 200 201 static int ima_measurements_open(struct inode *inode, struct file *file) 202 { 203 return seq_open(file, &ima_measurments_seqops); 204 } 205 206 static const struct file_operations ima_measurements_ops = { 207 .open = ima_measurements_open, 208 .read = seq_read, 209 .llseek = seq_lseek, 210 .release = seq_release, 211 }; 212 213 void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) 214 { 215 u32 i; 216 217 for (i = 0; i < size; i++) 218 seq_printf(m, "%02x", *(digest + i)); 219 } 220 221 /* print in ascii */ 222 static int ima_ascii_measurements_show(struct seq_file *m, void *v) 223 { 224 /* the list never shrinks, so we don't need a lock here */ 225 struct ima_queue_entry *qe = v; 226 struct ima_template_entry *e; 227 char *template_name; 228 int i; 229 230 /* get entry */ 231 e = qe->entry; 232 if (e == NULL) 233 return -1; 234 235 template_name = (e->template_desc->name[0] != '\0') ? 236 e->template_desc->name : e->template_desc->fmt; 237 238 /* 1st: PCR used (config option) */ 239 seq_printf(m, "%2d ", e->pcr); 240 241 /* 2nd: SHA1 template hash */ 242 ima_print_digest(m, e->digest, TPM_DIGEST_SIZE); 243 244 /* 3th: template name */ 245 seq_printf(m, " %s", template_name); 246 247 /* 4th: template specific data */ 248 for (i = 0; i < e->template_desc->num_fields; i++) { 249 seq_puts(m, " "); 250 if (e->template_data[i].len == 0) 251 continue; 252 253 e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII, 254 &e->template_data[i]); 255 } 256 seq_puts(m, "\n"); 257 return 0; 258 } 259 260 static const struct seq_operations ima_ascii_measurements_seqops = { 261 .start = ima_measurements_start, 262 .next = ima_measurements_next, 263 .stop = ima_measurements_stop, 264 .show = ima_ascii_measurements_show 265 }; 266 267 static int ima_ascii_measurements_open(struct inode *inode, struct file *file) 268 { 269 return seq_open(file, &ima_ascii_measurements_seqops); 270 } 271 272 static const struct file_operations ima_ascii_measurements_ops = { 273 .open = ima_ascii_measurements_open, 274 .read = seq_read, 275 .llseek = seq_lseek, 276 .release = seq_release, 277 }; 278 279 static ssize_t ima_read_policy(char *path) 280 { 281 void *data; 282 char *datap; 283 loff_t size; 284 int rc, pathlen = strlen(path); 285 286 char *p; 287 288 /* remove \n */ 289 datap = path; 290 strsep(&datap, "\n"); 291 292 rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY); 293 if (rc < 0) { 294 pr_err("Unable to open file: %s (%d)", path, rc); 295 return rc; 296 } 297 298 datap = data; 299 while (size > 0 && (p = strsep(&datap, "\n"))) { 300 pr_debug("rule: %s\n", p); 301 rc = ima_parse_add_rule(p); 302 if (rc < 0) 303 break; 304 size -= rc; 305 } 306 307 vfree(data); 308 if (rc < 0) 309 return rc; 310 else if (size) 311 return -EINVAL; 312 else 313 return pathlen; 314 } 315 316 static ssize_t ima_write_policy(struct file *file, const char __user *buf, 317 size_t datalen, loff_t *ppos) 318 { 319 char *data; 320 ssize_t result; 321 322 if (datalen >= PAGE_SIZE) 323 datalen = PAGE_SIZE - 1; 324 325 /* No partial writes. */ 326 result = -EINVAL; 327 if (*ppos != 0) 328 goto out; 329 330 data = memdup_user_nul(buf, datalen); 331 if (IS_ERR(data)) { 332 result = PTR_ERR(data); 333 goto out; 334 } 335 336 result = mutex_lock_interruptible(&ima_write_mutex); 337 if (result < 0) 338 goto out_free; 339 340 if (data[0] == '/') { 341 result = ima_read_policy(data); 342 } else if (ima_appraise & IMA_APPRAISE_POLICY) { 343 pr_err("signed policy file (specified as an absolute pathname) required\n"); 344 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, 345 "policy_update", "signed policy required", 346 1, 0); 347 if (ima_appraise & IMA_APPRAISE_ENFORCE) 348 result = -EACCES; 349 } else { 350 result = ima_parse_add_rule(data); 351 } 352 mutex_unlock(&ima_write_mutex); 353 out_free: 354 kfree(data); 355 out: 356 if (result < 0) 357 valid_policy = 0; 358 359 return result; 360 } 361 362 static struct dentry *ima_dir; 363 static struct dentry *ima_symlink; 364 static struct dentry *binary_runtime_measurements; 365 static struct dentry *ascii_runtime_measurements; 366 static struct dentry *runtime_measurements_count; 367 static struct dentry *violations; 368 static struct dentry *ima_policy; 369 370 enum ima_fs_flags { 371 IMA_FS_BUSY, 372 }; 373 374 static unsigned long ima_fs_flags; 375 376 #ifdef CONFIG_IMA_READ_POLICY 377 static const struct seq_operations ima_policy_seqops = { 378 .start = ima_policy_start, 379 .next = ima_policy_next, 380 .stop = ima_policy_stop, 381 .show = ima_policy_show, 382 }; 383 #endif 384 385 /* 386 * ima_open_policy: sequentialize access to the policy file 387 */ 388 static int ima_open_policy(struct inode *inode, struct file *filp) 389 { 390 if (!(filp->f_flags & O_WRONLY)) { 391 #ifndef CONFIG_IMA_READ_POLICY 392 return -EACCES; 393 #else 394 if ((filp->f_flags & O_ACCMODE) != O_RDONLY) 395 return -EACCES; 396 if (!capable(CAP_SYS_ADMIN)) 397 return -EPERM; 398 return seq_open(filp, &ima_policy_seqops); 399 #endif 400 } 401 if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags)) 402 return -EBUSY; 403 return 0; 404 } 405 406 /* 407 * ima_release_policy - start using the new measure policy rules. 408 * 409 * Initially, ima_measure points to the default policy rules, now 410 * point to the new policy rules, and remove the securityfs policy file, 411 * assuming a valid policy. 412 */ 413 static int ima_release_policy(struct inode *inode, struct file *file) 414 { 415 const char *cause = valid_policy ? "completed" : "failed"; 416 417 if ((file->f_flags & O_ACCMODE) == O_RDONLY) 418 return seq_release(inode, file); 419 420 if (valid_policy && ima_check_policy() < 0) { 421 cause = "failed"; 422 valid_policy = 0; 423 } 424 425 pr_info("policy update %s\n", cause); 426 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, 427 "policy_update", cause, !valid_policy, 0); 428 429 if (!valid_policy) { 430 ima_delete_rules(); 431 valid_policy = 1; 432 clear_bit(IMA_FS_BUSY, &ima_fs_flags); 433 return 0; 434 } 435 436 ima_update_policy(); 437 #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY) 438 securityfs_remove(ima_policy); 439 ima_policy = NULL; 440 #elif defined(CONFIG_IMA_WRITE_POLICY) 441 clear_bit(IMA_FS_BUSY, &ima_fs_flags); 442 #elif defined(CONFIG_IMA_READ_POLICY) 443 inode->i_mode &= ~S_IWUSR; 444 #endif 445 return 0; 446 } 447 448 static const struct file_operations ima_measure_policy_ops = { 449 .open = ima_open_policy, 450 .write = ima_write_policy, 451 .read = seq_read, 452 .release = ima_release_policy, 453 .llseek = generic_file_llseek, 454 }; 455 456 int __init ima_fs_init(void) 457 { 458 ima_dir = securityfs_create_dir("ima", integrity_dir); 459 if (IS_ERR(ima_dir)) 460 return -1; 461 462 ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima", 463 NULL); 464 if (IS_ERR(ima_symlink)) 465 goto out; 466 467 binary_runtime_measurements = 468 securityfs_create_file("binary_runtime_measurements", 469 S_IRUSR | S_IRGRP, ima_dir, NULL, 470 &ima_measurements_ops); 471 if (IS_ERR(binary_runtime_measurements)) 472 goto out; 473 474 ascii_runtime_measurements = 475 securityfs_create_file("ascii_runtime_measurements", 476 S_IRUSR | S_IRGRP, ima_dir, NULL, 477 &ima_ascii_measurements_ops); 478 if (IS_ERR(ascii_runtime_measurements)) 479 goto out; 480 481 runtime_measurements_count = 482 securityfs_create_file("runtime_measurements_count", 483 S_IRUSR | S_IRGRP, ima_dir, NULL, 484 &ima_measurements_count_ops); 485 if (IS_ERR(runtime_measurements_count)) 486 goto out; 487 488 violations = 489 securityfs_create_file("violations", S_IRUSR | S_IRGRP, 490 ima_dir, NULL, &ima_htable_violations_ops); 491 if (IS_ERR(violations)) 492 goto out; 493 494 ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS, 495 ima_dir, NULL, 496 &ima_measure_policy_ops); 497 if (IS_ERR(ima_policy)) 498 goto out; 499 500 return 0; 501 out: 502 securityfs_remove(violations); 503 securityfs_remove(runtime_measurements_count); 504 securityfs_remove(ascii_runtime_measurements); 505 securityfs_remove(binary_runtime_measurements); 506 securityfs_remove(ima_symlink); 507 securityfs_remove(ima_dir); 508 securityfs_remove(ima_policy); 509 return -1; 510 } 511