security/integrity/ima/ima

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
hash_setup
mmap_violation_check
ima_rdwr_violation_check
ima_check_last_writer
ima_file_free
process_measurement
ima_file_mmap
ima_bprm_check
ima_file_check
ima_post_create_tmpfile
ima_post_path_mknod
ima_read_file
ima_post_read_file
ima_load_data
process_buffer_measurement
ima_kexec_cmdline
init_ima
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Integrity Measurement Architecture
   4  *
   5  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
   6  *
   7  * Authors:
   8  * Reiner Sailer <sailer@watson.ibm.com>
   9  * Serge Hallyn <serue@us.ibm.com>
  10  * Kylene Hall <kylene@us.ibm.com>
  11  * Mimi Zohar <zohar@us.ibm.com>
  12  *
  13  * File: ima_main.c
  14  *      implements the IMA hooks: ima_bprm_check, ima_file_mmap,
  15  *      and ima_file_check.
  16  */
  17 
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19 
  20 #include <linux/module.h>
  21 #include <linux/file.h>
  22 #include <linux/binfmts.h>
  23 #include <linux/mount.h>
  24 #include <linux/mman.h>
  25 #include <linux/slab.h>
  26 #include <linux/xattr.h>
  27 #include <linux/ima.h>
  28 #include <linux/iversion.h>
  29 #include <linux/fs.h>
  30 
  31 #include "ima.h"
  32 
  33 #ifdef CONFIG_IMA_APPRAISE
  34 int ima_appraise = IMA_APPRAISE_ENFORCE;
  35 #else
  36 int ima_appraise;
  37 #endif
  38 
  39 int ima_hash_algo = HASH_ALGO_SHA1;
  40 static int hash_setup_done;
  41 
  42 static struct notifier_block ima_lsm_policy_notifier = {
  43         .notifier_call = ima_lsm_policy_change,
  44 };
  45 
  46 static int __init hash_setup(char *str)
  47 {
  48         struct ima_template_desc *template_desc = ima_template_desc_current();
  49         int i;
  50 
  51         if (hash_setup_done)
  52                 return 1;
  53 
  54         if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
  55                 if (strncmp(str, "sha1", 4) == 0)
  56                         ima_hash_algo = HASH_ALGO_SHA1;
  57                 else if (strncmp(str, "md5", 3) == 0)
  58                         ima_hash_algo = HASH_ALGO_MD5;
  59                 else
  60                         return 1;
  61                 goto out;
  62         }
  63 
  64         i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
  65         if (i < 0)
  66                 return 1;
  67 
  68         ima_hash_algo = i;
  69 out:
  70         hash_setup_done = 1;
  71         return 1;
  72 }
  73 __setup("ima_hash=", hash_setup);
  74 
  75 /* Prevent mmap'ing a file execute that is already mmap'ed write */
  76 static int mmap_violation_check(enum ima_hooks func, struct file *file,
  77                                 char **pathbuf, const char **pathname,
  78                                 char *filename)
  79 {
  80         struct inode *inode;
  81         int rc = 0;
  82 
  83         if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) {
  84                 rc = -ETXTBSY;
  85                 inode = file_inode(file);
  86 
  87                 if (!*pathbuf)  /* ima_rdwr_violation possibly pre-fetched */
  88                         *pathname = ima_d_path(&file->f_path, pathbuf,
  89                                                filename);
  90                 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname,
  91                                     "mmap_file", "mmapped_writers", rc, 0);
  92         }
  93         return rc;
  94 }
  95 
  96 /*
  97  * ima_rdwr_violation_check
  98  *
  99  * Only invalidate the PCR for measured files:
 100  *      - Opening a file for write when already open for read,
 101  *        results in a time of measure, time of use (ToMToU) error.
 102  *      - Opening a file for read when already open for write,
 103  *        could result in a file measurement error.
 104  *
 105  */
 106 static void ima_rdwr_violation_check(struct file *file,
 107                                      struct integrity_iint_cache *iint,
 108                                      int must_measure,
 109                                      char **pathbuf,
 110                                      const char **pathname,
 111                                      char *filename)
 112 {
 113         struct inode *inode = file_inode(file);
 114         fmode_t mode = file->f_mode;
 115         bool send_tomtou = false, send_writers = false;
 116 
 117         if (mode & FMODE_WRITE) {
 118                 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
 119                         if (!iint)
 120                                 iint = integrity_iint_find(inode);
 121                         /* IMA_MEASURE is set from reader side */
 122                         if (iint && test_bit(IMA_MUST_MEASURE,
 123                                                 &iint->atomic_flags))
 124                                 send_tomtou = true;
 125                 }
 126         } else {
 127                 if (must_measure)
 128                         set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
 129                 if (inode_is_open_for_write(inode) && must_measure)
 130                         send_writers = true;
 131         }
 132 
 133         if (!send_tomtou && !send_writers)
 134                 return;
 135 
 136         *pathname = ima_d_path(&file->f_path, pathbuf, filename);
 137 
 138         if (send_tomtou)
 139                 ima_add_violation(file, *pathname, iint,
 140                                   "invalid_pcr", "ToMToU");
 141         if (send_writers)
 142                 ima_add_violation(file, *pathname, iint,
 143                                   "invalid_pcr", "open_writers");
 144 }
 145 
 146 static void ima_check_last_writer(struct integrity_iint_cache *iint,
 147                                   struct inode *inode, struct file *file)
 148 {
 149         fmode_t mode = file->f_mode;
 150         bool update;
 151 
 152         if (!(mode & FMODE_WRITE))
 153                 return;
 154 
 155         mutex_lock(&iint->mutex);
 156         if (atomic_read(&inode->i_writecount) == 1) {
 157                 update = test_and_clear_bit(IMA_UPDATE_XATTR,
 158                                             &iint->atomic_flags);
 159                 if (!IS_I_VERSION(inode) ||
 160                     !inode_eq_iversion(inode, iint->version) ||
 161                     (iint->flags & IMA_NEW_FILE)) {
 162                         iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
 163                         iint->measured_pcrs = 0;
 164                         if (update)
 165                                 ima_update_xattr(iint, file);
 166                 }
 167         }
 168         mutex_unlock(&iint->mutex);
 169 }
 170 
 171 /**
 172  * ima_file_free - called on __fput()
 173  * @file: pointer to file structure being freed
 174  *
 175  * Flag files that changed, based on i_version
 176  */
 177 void ima_file_free(struct file *file)
 178 {
 179         struct inode *inode = file_inode(file);
 180         struct integrity_iint_cache *iint;
 181 
 182         if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 183                 return;
 184 
 185         iint = integrity_iint_find(inode);
 186         if (!iint)
 187                 return;
 188 
 189         ima_check_last_writer(iint, inode, file);
 190 }
 191 
 192 static int process_measurement(struct file *file, const struct cred *cred,
 193                                u32 secid, char *buf, loff_t size, int mask,
 194                                enum ima_hooks func)
 195 {
 196         struct inode *inode = file_inode(file);
 197         struct integrity_iint_cache *iint = NULL;
 198         struct ima_template_desc *template_desc = NULL;
 199         char *pathbuf = NULL;
 200         char filename[NAME_MAX];
 201         const char *pathname = NULL;
 202         int rc = 0, action, must_appraise = 0;
 203         int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 204         struct evm_ima_xattr_data *xattr_value = NULL;
 205         struct modsig *modsig = NULL;
 206         int xattr_len = 0;
 207         bool violation_check;
 208         enum hash_algo hash_algo;
 209 
 210         if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 211                 return 0;
 212 
 213         /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
 214          * bitmask based on the appraise/audit/measurement policy.
 215          * Included is the appraise submask.
 216          */
 217         action = ima_get_action(inode, cred, secid, mask, func, &pcr,
 218                                 &template_desc);
 219         violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
 220                            (ima_policy_flag & IMA_MEASURE));
 221         if (!action && !violation_check)
 222                 return 0;
 223 
 224         must_appraise = action & IMA_APPRAISE;
 225 
 226         /*  Is the appraise rule hook specific?  */
 227         if (action & IMA_FILE_APPRAISE)
 228                 func = FILE_CHECK;
 229 
 230         inode_lock(inode);
 231 
 232         if (action) {
 233                 iint = integrity_inode_get(inode);
 234                 if (!iint)
 235                         rc = -ENOMEM;
 236         }
 237 
 238         if (!rc && violation_check)
 239                 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
 240                                          &pathbuf, &pathname, filename);
 241 
 242         inode_unlock(inode);
 243 
 244         if (rc)
 245                 goto out;
 246         if (!action)
 247                 goto out;
 248 
 249         mutex_lock(&iint->mutex);
 250 
 251         if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
 252                 /* reset appraisal flags if ima_inode_post_setattr was called */
 253                 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
 254                                  IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
 255                                  IMA_ACTION_FLAGS);
 256 
 257         /*
 258          * Re-evaulate the file if either the xattr has changed or the
 259          * kernel has no way of detecting file change on the filesystem.
 260          * (Limited to privileged mounted filesystems.)
 261          */
 262         if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
 263             ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
 264              !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
 265              !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
 266                 iint->flags &= ~IMA_DONE_MASK;
 267                 iint->measured_pcrs = 0;
 268         }
 269 
 270         /* Determine if already appraised/measured based on bitmask
 271          * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
 272          *  IMA_AUDIT, IMA_AUDITED)
 273          */
 274         iint->flags |= action;
 275         action &= IMA_DO_MASK;
 276         action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
 277 
 278         /* If target pcr is already measured, unset IMA_MEASURE action */
 279         if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
 280                 action ^= IMA_MEASURE;
 281 
 282         /* HASH sets the digital signature and update flags, nothing else */
 283         if ((action & IMA_HASH) &&
 284             !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
 285                 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 286                 if ((xattr_value && xattr_len > 2) &&
 287                     (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
 288                         set_bit(IMA_DIGSIG, &iint->atomic_flags);
 289                 iint->flags |= IMA_HASHED;
 290                 action ^= IMA_HASH;
 291                 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 292         }
 293 
 294         /* Nothing to do, just return existing appraised status */
 295         if (!action) {
 296                 if (must_appraise) {
 297                         rc = mmap_violation_check(func, file, &pathbuf,
 298                                                   &pathname, filename);
 299                         if (!rc)
 300                                 rc = ima_get_cache_status(iint, func);
 301                 }
 302                 goto out_locked;
 303         }
 304 
 305         if ((action & IMA_APPRAISE_SUBMASK) ||
 306             strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 307                 /* read 'security.ima' */
 308                 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 309 
 310                 /*
 311                  * Read the appended modsig if allowed by the policy, and allow
 312                  * an additional measurement list entry, if needed, based on the
 313                  * template format and whether the file was already measured.
 314                  */
 315                 if (iint->flags & IMA_MODSIG_ALLOWED) {
 316                         rc = ima_read_modsig(func, buf, size, &modsig);
 317 
 318                         if (!rc && ima_template_has_modsig(template_desc) &&
 319                             iint->flags & IMA_MEASURED)
 320                                 action |= IMA_MEASURE;
 321                 }
 322         }
 323 
 324         hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 325 
 326         rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
 327         if (rc != 0 && rc != -EBADF && rc != -EINVAL)
 328                 goto out_locked;
 329 
 330         if (!pathbuf)   /* ima_rdwr_violation possibly pre-fetched */
 331                 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
 332 
 333         if (action & IMA_MEASURE)
 334                 ima_store_measurement(iint, file, pathname,
 335                                       xattr_value, xattr_len, modsig, pcr,
 336                                       template_desc);
 337         if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
 338                 inode_lock(inode);
 339                 rc = ima_appraise_measurement(func, iint, file, pathname,
 340                                               xattr_value, xattr_len, modsig);
 341                 inode_unlock(inode);
 342                 if (!rc)
 343                         rc = mmap_violation_check(func, file, &pathbuf,
 344                                                   &pathname, filename);
 345         }
 346         if (action & IMA_AUDIT)
 347                 ima_audit_measurement(iint, pathname);
 348 
 349         if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
 350                 rc = 0;
 351 out_locked:
 352         if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
 353              !(iint->flags & IMA_NEW_FILE))
 354                 rc = -EACCES;
 355         mutex_unlock(&iint->mutex);
 356         kfree(xattr_value);
 357         ima_free_modsig(modsig);
 358 out:
 359         if (pathbuf)
 360                 __putname(pathbuf);
 361         if (must_appraise) {
 362                 if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
 363                         return -EACCES;
 364                 if (file->f_mode & FMODE_WRITE)
 365                         set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 366         }
 367         return 0;
 368 }
 369 
 370 /**
 371  * ima_file_mmap - based on policy, collect/store measurement.
 372  * @file: pointer to the file to be measured (May be NULL)
 373  * @prot: contains the protection that will be applied by the kernel.
 374  *
 375  * Measure files being mmapped executable based on the ima_must_measure()
 376  * policy decision.
 377  *
 378  * On success return 0.  On integrity appraisal error, assuming the file
 379  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 380  */
 381 int ima_file_mmap(struct file *file, unsigned long prot)
 382 {
 383         u32 secid;
 384 
 385         if (file && (prot & PROT_EXEC)) {
 386                 security_task_getsecid(current, &secid);
 387                 return process_measurement(file, current_cred(), secid, NULL,
 388                                            0, MAY_EXEC, MMAP_CHECK);
 389         }
 390 
 391         return 0;
 392 }
 393 
 394 /**
 395  * ima_bprm_check - based on policy, collect/store measurement.
 396  * @bprm: contains the linux_binprm structure
 397  *
 398  * The OS protects against an executable file, already open for write,
 399  * from being executed in deny_write_access() and an executable file,
 400  * already open for execute, from being modified in get_write_access().
 401  * So we can be certain that what we verify and measure here is actually
 402  * what is being executed.
 403  *
 404  * On success return 0.  On integrity appraisal error, assuming the file
 405  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 406  */
 407 int ima_bprm_check(struct linux_binprm *bprm)
 408 {
 409         int ret;
 410         u32 secid;
 411 
 412         security_task_getsecid(current, &secid);
 413         ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
 414                                   MAY_EXEC, BPRM_CHECK);
 415         if (ret)
 416                 return ret;
 417 
 418         security_cred_getsecid(bprm->cred, &secid);
 419         return process_measurement(bprm->file, bprm->cred, secid, NULL, 0,
 420                                    MAY_EXEC, CREDS_CHECK);
 421 }
 422 
 423 /**
 424  * ima_path_check - based on policy, collect/store measurement.
 425  * @file: pointer to the file to be measured
 426  * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
 427  *
 428  * Measure files based on the ima_must_measure() policy decision.
 429  *
 430  * On success return 0.  On integrity appraisal error, assuming the file
 431  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 432  */
 433 int ima_file_check(struct file *file, int mask)
 434 {
 435         u32 secid;
 436 
 437         security_task_getsecid(current, &secid);
 438         return process_measurement(file, current_cred(), secid, NULL, 0,
 439                                    mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
 440                                            MAY_APPEND), FILE_CHECK);
 441 }
 442 EXPORT_SYMBOL_GPL(ima_file_check);
 443 
 444 /**
 445  * ima_post_create_tmpfile - mark newly created tmpfile as new
 446  * @file : newly created tmpfile
 447  *
 448  * No measuring, appraising or auditing of newly created tmpfiles is needed.
 449  * Skip calling process_measurement(), but indicate which newly, created
 450  * tmpfiles are in policy.
 451  */
 452 void ima_post_create_tmpfile(struct inode *inode)
 453 {
 454         struct integrity_iint_cache *iint;
 455         int must_appraise;
 456 
 457         must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
 458         if (!must_appraise)
 459                 return;
 460 
 461         /* Nothing to do if we can't allocate memory */
 462         iint = integrity_inode_get(inode);
 463         if (!iint)
 464                 return;
 465 
 466         /* needed for writing the security xattrs */
 467         set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 468         iint->ima_file_status = INTEGRITY_PASS;
 469 }
 470 
 471 /**
 472  * ima_post_path_mknod - mark as a new inode
 473  * @dentry: newly created dentry
 474  *
 475  * Mark files created via the mknodat syscall as new, so that the
 476  * file data can be written later.
 477  */
 478 void ima_post_path_mknod(struct dentry *dentry)
 479 {
 480         struct integrity_iint_cache *iint;
 481         struct inode *inode = dentry->d_inode;
 482         int must_appraise;
 483 
 484         must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
 485         if (!must_appraise)
 486                 return;
 487 
 488         /* Nothing to do if we can't allocate memory */
 489         iint = integrity_inode_get(inode);
 490         if (!iint)
 491                 return;
 492 
 493         /* needed for re-opening empty files */
 494         iint->flags |= IMA_NEW_FILE;
 495 }
 496 
 497 /**
 498  * ima_read_file - pre-measure/appraise hook decision based on policy
 499  * @file: pointer to the file to be measured/appraised/audit
 500  * @read_id: caller identifier
 501  *
 502  * Permit reading a file based on policy. The policy rules are written
 503  * in terms of the policy identifier.  Appraising the integrity of
 504  * a file requires a file descriptor.
 505  *
 506  * For permission return 0, otherwise return -EACCES.
 507  */
 508 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 509 {
 510         /*
 511          * READING_FIRMWARE_PREALLOC_BUFFER
 512          *
 513          * Do devices using pre-allocated memory run the risk of the
 514          * firmware being accessible to the device prior to the completion
 515          * of IMA's signature verification any more than when using two
 516          * buffers?
 517          */
 518         return 0;
 519 }
 520 
 521 const int read_idmap[READING_MAX_ID] = {
 522         [READING_FIRMWARE] = FIRMWARE_CHECK,
 523         [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
 524         [READING_MODULE] = MODULE_CHECK,
 525         [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
 526         [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
 527         [READING_POLICY] = POLICY_CHECK
 528 };
 529 
 530 /**
 531  * ima_post_read_file - in memory collect/appraise/audit measurement
 532  * @file: pointer to the file to be measured/appraised/audit
 533  * @buf: pointer to in memory file contents
 534  * @size: size of in memory file contents
 535  * @read_id: caller identifier
 536  *
 537  * Measure/appraise/audit in memory file based on policy.  Policy rules
 538  * are written in terms of a policy identifier.
 539  *
 540  * On success return 0.  On integrity appraisal error, assuming the file
 541  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 542  */
 543 int ima_post_read_file(struct file *file, void *buf, loff_t size,
 544                        enum kernel_read_file_id read_id)
 545 {
 546         enum ima_hooks func;
 547         u32 secid;
 548 
 549         if (!file && read_id == READING_FIRMWARE) {
 550                 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
 551                     (ima_appraise & IMA_APPRAISE_ENFORCE)) {
 552                         pr_err("Prevent firmware loading_store.\n");
 553                         return -EACCES; /* INTEGRITY_UNKNOWN */
 554                 }
 555                 return 0;
 556         }
 557 
 558         /* permit signed certs */
 559         if (!file && read_id == READING_X509_CERTIFICATE)
 560                 return 0;
 561 
 562         if (!file || !buf || size == 0) { /* should never happen */
 563                 if (ima_appraise & IMA_APPRAISE_ENFORCE)
 564                         return -EACCES;
 565                 return 0;
 566         }
 567 
 568         func = read_idmap[read_id] ?: FILE_CHECK;
 569         security_task_getsecid(current, &secid);
 570         return process_measurement(file, current_cred(), secid, buf, size,
 571                                    MAY_READ, func);
 572 }
 573 
 574 /**
 575  * ima_load_data - appraise decision based on policy
 576  * @id: kernel load data caller identifier
 577  *
 578  * Callers of this LSM hook can not measure, appraise, or audit the
 579  * data provided by userspace.  Enforce policy rules requring a file
 580  * signature (eg. kexec'ed kernel image).
 581  *
 582  * For permission return 0, otherwise return -EACCES.
 583  */
 584 int ima_load_data(enum kernel_load_data_id id)
 585 {
 586         bool ima_enforce, sig_enforce;
 587 
 588         ima_enforce =
 589                 (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
 590 
 591         switch (id) {
 592         case LOADING_KEXEC_IMAGE:
 593                 if (IS_ENABLED(CONFIG_KEXEC_SIG)
 594                     && arch_ima_get_secureboot()) {
 595                         pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
 596                         return -EACCES;
 597                 }
 598 
 599                 if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) {
 600                         pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
 601                         return -EACCES; /* INTEGRITY_UNKNOWN */
 602                 }
 603                 break;
 604         case LOADING_FIRMWARE:
 605                 if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) {
 606                         pr_err("Prevent firmware sysfs fallback loading.\n");
 607                         return -EACCES; /* INTEGRITY_UNKNOWN */
 608                 }
 609                 break;
 610         case LOADING_MODULE:
 611                 sig_enforce = is_module_sig_enforced();
 612 
 613                 if (ima_enforce && (!sig_enforce
 614                                     && (ima_appraise & IMA_APPRAISE_MODULES))) {
 615                         pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
 616                         return -EACCES; /* INTEGRITY_UNKNOWN */
 617                 }
 618         default:
 619                 break;
 620         }
 621         return 0;
 622 }
 623 
 624 /*
 625  * process_buffer_measurement - Measure the buffer to ima log.
 626  * @buf: pointer to the buffer that needs to be added to the log.
 627  * @size: size of buffer(in bytes).
 628  * @eventname: event name to be used for the buffer entry.
 629  * @cred: a pointer to a credentials structure for user validation.
 630  * @secid: the secid of the task to be validated.
 631  *
 632  * Based on policy, the buffer is measured into the ima log.
 633  */
 634 static void process_buffer_measurement(const void *buf, int size,
 635                                        const char *eventname,
 636                                        const struct cred *cred, u32 secid)
 637 {
 638         int ret = 0;
 639         struct ima_template_entry *entry = NULL;
 640         struct integrity_iint_cache iint = {};
 641         struct ima_event_data event_data = {.iint = &iint,
 642                                             .filename = eventname,
 643                                             .buf = buf,
 644                                             .buf_len = size};
 645         struct ima_template_desc *template_desc = NULL;
 646         struct {
 647                 struct ima_digest_data hdr;
 648                 char digest[IMA_MAX_DIGEST_SIZE];
 649         } hash = {};
 650         int violation = 0;
 651         int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 652         int action = 0;
 653 
 654         action = ima_get_action(NULL, cred, secid, 0, KEXEC_CMDLINE, &pcr,
 655                                 &template_desc);
 656         if (!(action & IMA_MEASURE))
 657                 return;
 658 
 659         iint.ima_hash = &hash.hdr;
 660         iint.ima_hash->algo = ima_hash_algo;
 661         iint.ima_hash->length = hash_digest_size[ima_hash_algo];
 662 
 663         ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
 664         if (ret < 0)
 665                 goto out;
 666 
 667         ret = ima_alloc_init_template(&event_data, &entry, template_desc);
 668         if (ret < 0)
 669                 goto out;
 670 
 671         ret = ima_store_template(entry, violation, NULL, buf, pcr);
 672 
 673         if (ret < 0)
 674                 ima_free_template_entry(entry);
 675 
 676 out:
 677         return;
 678 }
 679 
 680 /**
 681  * ima_kexec_cmdline - measure kexec cmdline boot args
 682  * @buf: pointer to buffer
 683  * @size: size of buffer
 684  *
 685  * Buffers can only be measured, not appraised.
 686  */
 687 void ima_kexec_cmdline(const void *buf, int size)
 688 {
 689         u32 secid;
 690 
 691         if (buf && size != 0) {
 692                 security_task_getsecid(current, &secid);
 693                 process_buffer_measurement(buf, size, "kexec-cmdline",
 694                                            current_cred(), secid);
 695         }
 696 }
 697 
 698 static int __init init_ima(void)
 699 {
 700         int error;
 701 
 702         ima_init_template_list();
 703         hash_setup(CONFIG_IMA_DEFAULT_HASH);
 704         error = ima_init();
 705 
 706         if (error && strcmp(hash_algo_name[ima_hash_algo],
 707                             CONFIG_IMA_DEFAULT_HASH) != 0) {
 708                 pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
 709                         hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
 710                 hash_setup_done = 0;
 711                 hash_setup(CONFIG_IMA_DEFAULT_HASH);
 712                 error = ima_init();
 713         }
 714 
 715         error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
 716         if (error)
 717                 pr_warn("Couldn't register LSM notifier, error %d\n", error);
 718 
 719         if (!error)
 720                 ima_update_policy_flag();
 721 
 722         return error;
 723 }
 724 
 725 late_initcall(init_ima);        /* Start IMA after the TPM is available */
/* [<][>][^][v][top][bottom][index][help] */
root/security/integrity/ima/ima_main.c

DEFINITIONS
