2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
5 * Reiner Sailer <sailer@watson.ibm.com>
6 * Serge Hallyn <serue@us.ibm.com>
7 * Kylene Hall <kylene@us.ibm.com>
8 * Mimi Zohar <zohar@us.ibm.com>
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2 of the
16 * implements the IMA hooks: ima_bprm_check, ima_file_mmap,
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 #include <linux/module.h>
23 #include <linux/file.h>
24 #include <linux/binfmts.h>
25 #include <linux/mount.h>
26 #include <linux/mman.h>
27 #include <linux/slab.h>
28 #include <linux/xattr.h>
29 #include <linux/ima.h>
35 #ifdef CONFIG_IMA_APPRAISE
36 int ima_appraise = IMA_APPRAISE_ENFORCE;
41 int ima_hash_algo = HASH_ALGO_SHA1;
42 static int hash_setup_done;
44 static int __init hash_setup(char *str)
46 struct ima_template_desc *template_desc = ima_template_desc_current();
52 if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
53 if (strncmp(str, "sha1", 4) == 0)
54 ima_hash_algo = HASH_ALGO_SHA1;
55 else if (strncmp(str, "md5", 3) == 0)
56 ima_hash_algo = HASH_ALGO_MD5;
62 for (i = 0; i < HASH_ALGO__LAST; i++) {
63 if (strcmp(str, hash_algo_name[i]) == 0) {
68 if (i == HASH_ALGO__LAST)
74 __setup("ima_hash=", hash_setup);
77 * ima_rdwr_violation_check
79 * Only invalidate the PCR for measured files:
80 * - Opening a file for write when already open for read,
81 * results in a time of measure, time of use (ToMToU) error.
82 * - Opening a file for read when already open for write,
83 * could result in a file measurement error.
86 static void ima_rdwr_violation_check(struct file *file,
87 struct integrity_iint_cache *iint,
90 const char **pathname)
92 struct inode *inode = file_inode(file);
93 char filename[NAME_MAX];
94 fmode_t mode = file->f_mode;
95 bool send_tomtou = false, send_writers = false;
97 if (mode & FMODE_WRITE) {
98 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
100 iint = integrity_iint_find(inode);
101 /* IMA_MEASURE is set from reader side */
102 if (iint && test_bit(IMA_MUST_MEASURE,
103 &iint->atomic_flags))
108 set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
109 if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
113 if (!send_tomtou && !send_writers)
116 *pathname = ima_d_path(&file->f_path, pathbuf, filename);
119 ima_add_violation(file, *pathname, iint,
120 "invalid_pcr", "ToMToU");
122 ima_add_violation(file, *pathname, iint,
123 "invalid_pcr", "open_writers");
126 static void ima_check_last_writer(struct integrity_iint_cache *iint,
127 struct inode *inode, struct file *file)
129 fmode_t mode = file->f_mode;
132 if (!(mode & FMODE_WRITE))
135 mutex_lock(&iint->mutex);
136 if (atomic_read(&inode->i_writecount) == 1) {
137 update = test_and_clear_bit(IMA_UPDATE_XATTR,
138 &iint->atomic_flags);
139 if ((iint->version != inode->i_version) ||
140 (iint->flags & IMA_NEW_FILE)) {
141 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
142 iint->measured_pcrs = 0;
144 ima_update_xattr(iint, file);
147 mutex_unlock(&iint->mutex);
151 * ima_file_free - called on __fput()
152 * @file: pointer to file structure being freed
154 * Flag files that changed, based on i_version
156 void ima_file_free(struct file *file)
158 struct inode *inode = file_inode(file);
159 struct integrity_iint_cache *iint;
161 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
164 iint = integrity_iint_find(inode);
168 ima_check_last_writer(iint, inode, file);
171 static int process_measurement(struct file *file, char *buf, loff_t size,
172 int mask, enum ima_hooks func, int opened)
174 struct inode *inode = file_inode(file);
175 struct integrity_iint_cache *iint = NULL;
176 struct ima_template_desc *template_desc;
177 char *pathbuf = NULL;
178 char filename[NAME_MAX];
179 const char *pathname = NULL;
180 int rc = 0, action, must_appraise = 0;
181 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
182 struct evm_ima_xattr_data *xattr_value = NULL;
184 bool violation_check;
185 enum hash_algo hash_algo;
187 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
190 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
191 * bitmask based on the appraise/audit/measurement policy.
192 * Included is the appraise submask.
194 action = ima_get_action(inode, mask, func, &pcr);
195 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
196 (ima_policy_flag & IMA_MEASURE));
197 if (!action && !violation_check)
200 must_appraise = action & IMA_APPRAISE;
202 /* Is the appraise rule hook specific? */
203 if (action & IMA_FILE_APPRAISE)
209 iint = integrity_inode_get(inode);
214 if (!rc && violation_check)
215 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
216 &pathbuf, &pathname);
225 mutex_lock(&iint->mutex);
227 if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
228 /* reset appraisal flags if ima_inode_post_setattr was called */
229 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
230 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
233 if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags))
234 /* reset all flags if ima_inode_setxattr was called */
235 iint->flags &= ~IMA_DONE_MASK;
237 /* Determine if already appraised/measured based on bitmask
238 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
239 * IMA_AUDIT, IMA_AUDITED)
241 iint->flags |= action;
242 action &= IMA_DO_MASK;
243 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
245 /* If target pcr is already measured, unset IMA_MEASURE action */
246 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
247 action ^= IMA_MEASURE;
249 /* Nothing to do, just return existing appraised status */
252 rc = ima_get_cache_status(iint, func);
256 template_desc = ima_template_desc_current();
257 if ((action & IMA_APPRAISE_SUBMASK) ||
258 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
259 /* read 'security.ima' */
260 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
262 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
264 rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
265 if (rc != 0 && rc != -EBADF && rc != -EINVAL)
268 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
269 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
271 if (action & IMA_MEASURE)
272 ima_store_measurement(iint, file, pathname,
273 xattr_value, xattr_len, pcr);
274 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
276 rc = ima_appraise_measurement(func, iint, file, pathname,
277 xattr_value, xattr_len, opened);
280 if (action & IMA_AUDIT)
281 ima_audit_measurement(iint, pathname);
283 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
286 if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
287 !(iint->flags & IMA_NEW_FILE))
289 mutex_unlock(&iint->mutex);
295 if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
297 if (file->f_mode & FMODE_WRITE)
298 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
304 * ima_file_mmap - based on policy, collect/store measurement.
305 * @file: pointer to the file to be measured (May be NULL)
306 * @reqprot: protection requested by the application
307 * @prot: protection that will be applied by the kernel
308 * @flags: operational flags
310 * Measure files being mmapped executable based on the ima_must_measure()
313 * On success return 0. On integrity appraisal error, assuming the file
314 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
316 int ima_file_mmap(struct file *file, unsigned long reqprot,
317 unsigned long prot, unsigned long flags)
319 if (file && (prot & PROT_EXEC))
320 return process_measurement(file, NULL, 0, MAY_EXEC,
326 * ima_bprm_check - based on policy, collect/store measurement.
327 * @bprm: contains the linux_binprm structure
329 * The OS protects against an executable file, already open for write,
330 * from being executed in deny_write_access() and an executable file,
331 * already open for execute, from being modified in get_write_access().
332 * So we can be certain that what we verify and measure here is actually
333 * what is being executed.
335 * On success return 0. On integrity appraisal error, assuming the file
336 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
338 int ima_bprm_check(struct linux_binprm *bprm)
340 return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
345 * ima_path_check - based on policy, collect/store measurement.
346 * @file: pointer to the file to be measured
347 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
349 * Measure files based on the ima_must_measure() policy decision.
351 * On success return 0. On integrity appraisal error, assuming the file
352 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
354 int ima_file_check(struct file *file, int mask, int opened)
356 return process_measurement(file, NULL, 0,
357 mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
358 MAY_APPEND), FILE_CHECK, opened);
360 EXPORT_SYMBOL_GPL(ima_file_check);
363 * ima_post_path_mknod - mark as a new inode
364 * @dentry: newly created dentry
366 * Mark files created via the mknodat syscall as new, so that the
367 * file data can be written later.
369 void ima_post_path_mknod(struct dentry *dentry)
371 struct integrity_iint_cache *iint;
372 struct inode *inode = dentry->d_inode;
375 must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
379 iint = integrity_inode_get(inode);
381 iint->flags |= IMA_NEW_FILE;
385 * ima_read_file - pre-measure/appraise hook decision based on policy
386 * @file: pointer to the file to be measured/appraised/audit
387 * @read_id: caller identifier
389 * Permit reading a file based on policy. The policy rules are written
390 * in terms of the policy identifier. Appraising the integrity of
391 * a file requires a file descriptor.
393 * For permission return 0, otherwise return -EACCES.
395 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
397 if (!file && read_id == READING_MODULE) {
398 #ifndef CONFIG_MODULE_SIG_FORCE
399 if ((ima_appraise & IMA_APPRAISE_MODULES) &&
400 (ima_appraise & IMA_APPRAISE_ENFORCE))
401 return -EACCES; /* INTEGRITY_UNKNOWN */
403 return 0; /* We rely on module signature checking */
408 static int read_idmap[READING_MAX_ID] = {
409 [READING_FIRMWARE] = FIRMWARE_CHECK,
410 [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
411 [READING_MODULE] = MODULE_CHECK,
412 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
413 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
414 [READING_POLICY] = POLICY_CHECK
418 * ima_post_read_file - in memory collect/appraise/audit measurement
419 * @file: pointer to the file to be measured/appraised/audit
420 * @buf: pointer to in memory file contents
421 * @size: size of in memory file contents
422 * @read_id: caller identifier
424 * Measure/appraise/audit in memory file based on policy. Policy rules
425 * are written in terms of a policy identifier.
427 * On success return 0. On integrity appraisal error, assuming the file
428 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
430 int ima_post_read_file(struct file *file, void *buf, loff_t size,
431 enum kernel_read_file_id read_id)
435 if (!file && read_id == READING_FIRMWARE) {
436 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
437 (ima_appraise & IMA_APPRAISE_ENFORCE))
438 return -EACCES; /* INTEGRITY_UNKNOWN */
442 if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
445 if (!file || !buf || size == 0) { /* should never happen */
446 if (ima_appraise & IMA_APPRAISE_ENFORCE)
451 func = read_idmap[read_id] ?: FILE_CHECK;
452 return process_measurement(file, buf, size, MAY_READ, func, 0);
455 static int __init init_ima(void)
459 ima_init_template_list();
460 hash_setup(CONFIG_IMA_DEFAULT_HASH);
463 if (error && strcmp(hash_algo_name[ima_hash_algo],
464 CONFIG_IMA_DEFAULT_HASH) != 0) {
465 pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
466 hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
468 hash_setup(CONFIG_IMA_DEFAULT_HASH);
474 ima_update_policy_flag();
479 late_initcall(init_ima); /* Start IMA after the TPM is available */
481 MODULE_DESCRIPTION("Integrity Measurement Architecture");
482 MODULE_LICENSE("GPL");