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,
19 #include <linux/module.h>
20 #include <linux/file.h>
21 #include <linux/binfmts.h>
22 #include <linux/mount.h>
23 #include <linux/mman.h>
24 #include <linux/slab.h>
25 #include <linux/xattr.h>
26 #include <linux/ima.h>
32 #ifdef CONFIG_IMA_APPRAISE
33 int ima_appraise = IMA_APPRAISE_ENFORCE;
38 int ima_hash_algo = HASH_ALGO_SHA1;
39 static int hash_setup_done;
41 static int __init hash_setup(char *str)
43 struct ima_template_desc *template_desc = ima_template_desc_current();
49 if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
50 if (strncmp(str, "sha1", 4) == 0)
51 ima_hash_algo = HASH_ALGO_SHA1;
52 else if (strncmp(str, "md5", 3) == 0)
53 ima_hash_algo = HASH_ALGO_MD5;
57 for (i = 0; i < HASH_ALGO__LAST; i++) {
58 if (strcmp(str, hash_algo_name[i]) == 0) {
67 __setup("ima_hash=", hash_setup);
70 * ima_rdwr_violation_check
72 * Only invalidate the PCR for measured files:
73 * - Opening a file for write when already open for read,
74 * results in a time of measure, time of use (ToMToU) error.
75 * - Opening a file for read when already open for write,
76 * could result in a file measurement error.
79 static void ima_rdwr_violation_check(struct file *file,
80 struct integrity_iint_cache *iint,
83 const char **pathname)
85 struct inode *inode = file_inode(file);
86 fmode_t mode = file->f_mode;
87 bool send_tomtou = false, send_writers = false;
89 if (mode & FMODE_WRITE) {
90 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
92 iint = integrity_iint_find(inode);
93 /* IMA_MEASURE is set from reader side */
94 if (iint && (iint->flags & IMA_MEASURE))
98 if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
102 if (!send_tomtou && !send_writers)
105 *pathname = ima_d_path(&file->f_path, pathbuf);
108 ima_add_violation(file, *pathname, iint,
109 "invalid_pcr", "ToMToU");
111 ima_add_violation(file, *pathname, iint,
112 "invalid_pcr", "open_writers");
115 static void ima_check_last_writer(struct integrity_iint_cache *iint,
116 struct inode *inode, struct file *file)
118 fmode_t mode = file->f_mode;
120 if (!(mode & FMODE_WRITE))
124 if (atomic_read(&inode->i_writecount) == 1) {
125 if ((iint->version != inode->i_version) ||
126 (iint->flags & IMA_NEW_FILE)) {
127 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
128 iint->measured_pcrs = 0;
129 if (iint->flags & IMA_APPRAISE)
130 ima_update_xattr(iint, file);
137 * ima_file_free - called on __fput()
138 * @file: pointer to file structure being freed
140 * Flag files that changed, based on i_version
142 void ima_file_free(struct file *file)
144 struct inode *inode = file_inode(file);
145 struct integrity_iint_cache *iint;
147 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
150 iint = integrity_iint_find(inode);
154 ima_check_last_writer(iint, inode, file);
157 static int process_measurement(struct file *file, char *buf, loff_t size,
158 int mask, enum ima_hooks func, int opened)
160 struct inode *inode = file_inode(file);
161 struct integrity_iint_cache *iint = NULL;
162 struct ima_template_desc *template_desc;
163 char *pathbuf = NULL;
164 const char *pathname = NULL;
165 int rc = -ENOMEM, action, must_appraise;
166 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
167 struct evm_ima_xattr_data *xattr_value = NULL;
169 bool violation_check;
170 enum hash_algo hash_algo;
172 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
175 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
176 * bitmask based on the appraise/audit/measurement policy.
177 * Included is the appraise submask.
179 action = ima_get_action(inode, mask, func, &pcr);
180 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
181 (ima_policy_flag & IMA_MEASURE));
182 if (!action && !violation_check)
185 must_appraise = action & IMA_APPRAISE;
187 /* Is the appraise rule hook specific? */
188 if (action & IMA_FILE_APPRAISE)
194 iint = integrity_inode_get(inode);
199 if (violation_check) {
200 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
201 &pathbuf, &pathname);
208 /* Determine if already appraised/measured based on bitmask
209 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
210 * IMA_AUDIT, IMA_AUDITED)
212 iint->flags |= action;
213 action &= IMA_DO_MASK;
214 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
216 /* If target pcr is already measured, unset IMA_MEASURE action */
217 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
218 action ^= IMA_MEASURE;
220 /* Nothing to do, just return existing appraised status */
223 rc = ima_get_cache_status(iint, func);
227 template_desc = ima_template_desc_current();
228 if ((action & IMA_APPRAISE_SUBMASK) ||
229 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
230 /* read 'security.ima' */
231 xattr_len = ima_read_xattr(file->f_path.dentry, &xattr_value);
233 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
235 rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
237 if (file->f_flags & O_DIRECT)
238 rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
242 if (!pathname) /* ima_rdwr_violation possibly pre-fetched */
243 pathname = ima_d_path(&file->f_path, &pathbuf);
245 if (action & IMA_MEASURE)
246 ima_store_measurement(iint, file, pathname,
247 xattr_value, xattr_len, pcr);
248 if (action & IMA_APPRAISE_SUBMASK)
249 rc = ima_appraise_measurement(func, iint, file, pathname,
250 xattr_value, xattr_len, opened);
251 if (action & IMA_AUDIT)
252 ima_audit_measurement(iint, pathname);
255 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
256 !(iint->flags & IMA_NEW_FILE))
264 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
270 * ima_file_mmap - based on policy, collect/store measurement.
271 * @file: pointer to the file to be measured (May be NULL)
272 * @prot: contains the protection that will be applied by the kernel.
274 * Measure files being mmapped executable based on the ima_must_measure()
277 * On success return 0. On integrity appraisal error, assuming the file
278 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
280 int ima_file_mmap(struct file *file, unsigned long prot)
282 if (file && (prot & PROT_EXEC))
283 return process_measurement(file, NULL, 0, MAY_EXEC,
289 * ima_bprm_check - based on policy, collect/store measurement.
290 * @bprm: contains the linux_binprm structure
292 * The OS protects against an executable file, already open for write,
293 * from being executed in deny_write_access() and an executable file,
294 * already open for execute, from being modified in get_write_access().
295 * So we can be certain that what we verify and measure here is actually
296 * what is being executed.
298 * On success return 0. On integrity appraisal error, assuming the file
299 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
301 int ima_bprm_check(struct linux_binprm *bprm)
303 return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
308 * ima_path_check - based on policy, collect/store measurement.
309 * @file: pointer to the file to be measured
310 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
312 * Measure files based on the ima_must_measure() policy decision.
314 * On success return 0. On integrity appraisal error, assuming the file
315 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
317 int ima_file_check(struct file *file, int mask, int opened)
319 return process_measurement(file, NULL, 0,
320 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
323 EXPORT_SYMBOL_GPL(ima_file_check);
326 * ima_post_path_mknod - mark as a new inode
327 * @dentry: newly created dentry
329 * Mark files created via the mknodat syscall as new, so that the
330 * file data can be written later.
332 void ima_post_path_mknod(struct dentry *dentry)
334 struct integrity_iint_cache *iint;
335 struct inode *inode = dentry->d_inode;
338 must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
342 iint = integrity_inode_get(inode);
344 iint->flags |= IMA_NEW_FILE;
348 * ima_read_file - pre-measure/appraise hook decision based on policy
349 * @file: pointer to the file to be measured/appraised/audit
350 * @read_id: caller identifier
352 * Permit reading a file based on policy. The policy rules are written
353 * in terms of the policy identifier. Appraising the integrity of
354 * a file requires a file descriptor.
356 * For permission return 0, otherwise return -EACCES.
358 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
360 if (!file && read_id == READING_MODULE) {
361 #ifndef CONFIG_MODULE_SIG_FORCE
362 if ((ima_appraise & IMA_APPRAISE_MODULES) &&
363 (ima_appraise & IMA_APPRAISE_ENFORCE))
364 return -EACCES; /* INTEGRITY_UNKNOWN */
366 return 0; /* We rely on module signature checking */
371 static int read_idmap[READING_MAX_ID] = {
372 [READING_FIRMWARE] = FIRMWARE_CHECK,
373 [READING_MODULE] = MODULE_CHECK,
374 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
375 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
376 [READING_POLICY] = POLICY_CHECK
380 * ima_post_read_file - in memory collect/appraise/audit measurement
381 * @file: pointer to the file to be measured/appraised/audit
382 * @buf: pointer to in memory file contents
383 * @size: size of in memory file contents
384 * @read_id: caller identifier
386 * Measure/appraise/audit in memory file based on policy. Policy rules
387 * are written in terms of a policy identifier.
389 * On success return 0. On integrity appraisal error, assuming the file
390 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
392 int ima_post_read_file(struct file *file, void *buf, loff_t size,
393 enum kernel_read_file_id read_id)
397 if (!file && read_id == READING_FIRMWARE) {
398 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
399 (ima_appraise & IMA_APPRAISE_ENFORCE))
400 return -EACCES; /* INTEGRITY_UNKNOWN */
404 if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
407 if (!file || !buf || size == 0) { /* should never happen */
408 if (ima_appraise & IMA_APPRAISE_ENFORCE)
413 func = read_idmap[read_id] ?: FILE_CHECK;
414 return process_measurement(file, buf, size, MAY_READ, func, 0);
417 static int __init init_ima(void)
421 hash_setup(CONFIG_IMA_DEFAULT_HASH);
425 ima_update_policy_flag();
430 late_initcall(init_ima); /* Start IMA after the TPM is available */
432 MODULE_DESCRIPTION("Integrity Measurement Architecture");
433 MODULE_LICENSE("GPL");