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>
27 #include <linux/iversion.h>
33 #ifdef CONFIG_IMA_APPRAISE
34 int ima_appraise = IMA_APPRAISE_ENFORCE;
39 int ima_hash_algo = HASH_ALGO_SHA1;
40 static int hash_setup_done;
42 static int __init hash_setup(char *str)
44 struct ima_template_desc *template_desc = ima_template_desc_current();
50 if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
51 if (strncmp(str, "sha1", 4) == 0)
52 ima_hash_algo = HASH_ALGO_SHA1;
53 else if (strncmp(str, "md5", 3) == 0)
54 ima_hash_algo = HASH_ALGO_MD5;
60 for (i = 0; i < HASH_ALGO__LAST; i++) {
61 if (strcmp(str, hash_algo_name[i]) == 0) {
66 if (i == HASH_ALGO__LAST)
72 __setup("ima_hash=", hash_setup);
75 * ima_rdwr_violation_check
77 * Only invalidate the PCR for measured files:
78 * - Opening a file for write when already open for read,
79 * results in a time of measure, time of use (ToMToU) error.
80 * - Opening a file for read when already open for write,
81 * could result in a file measurement error.
84 static void ima_rdwr_violation_check(struct file *file,
85 struct integrity_iint_cache *iint,
88 const char **pathname)
90 struct inode *inode = file_inode(file);
91 char filename[NAME_MAX];
92 fmode_t mode = file->f_mode;
93 bool send_tomtou = false, send_writers = false;
95 if (mode & FMODE_WRITE) {
96 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
98 iint = integrity_iint_find(inode);
99 /* IMA_MEASURE is set from reader side */
100 if (iint && (iint->flags & IMA_MEASURE))
104 if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
108 if (!send_tomtou && !send_writers)
111 *pathname = ima_d_path(&file->f_path, pathbuf, filename);
114 ima_add_violation(file, *pathname, iint,
115 "invalid_pcr", "ToMToU");
117 ima_add_violation(file, *pathname, iint,
118 "invalid_pcr", "open_writers");
121 static void ima_check_last_writer(struct integrity_iint_cache *iint,
122 struct inode *inode, struct file *file)
124 fmode_t mode = file->f_mode;
126 if (!(mode & FMODE_WRITE))
130 if (atomic_read(&inode->i_writecount) == 1) {
131 if (!IS_I_VERSION(inode) ||
132 inode_cmp_iversion(inode, iint->version) ||
133 (iint->flags & IMA_NEW_FILE)) {
134 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
135 iint->measured_pcrs = 0;
136 if (iint->flags & IMA_APPRAISE)
137 ima_update_xattr(iint, file);
144 * ima_file_free - called on __fput()
145 * @file: pointer to file structure being freed
147 * Flag files that changed, based on i_version
149 void ima_file_free(struct file *file)
151 struct inode *inode = file_inode(file);
152 struct integrity_iint_cache *iint;
154 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
157 iint = integrity_iint_find(inode);
161 ima_check_last_writer(iint, inode, file);
164 static int process_measurement(struct file *file, char *buf, loff_t size,
165 int mask, enum ima_hooks func, int opened)
167 struct inode *inode = file_inode(file);
168 struct integrity_iint_cache *iint = NULL;
169 struct ima_template_desc *template_desc;
170 char *pathbuf = NULL;
171 char filename[NAME_MAX];
172 const char *pathname = NULL;
173 int rc = -ENOMEM, action, must_appraise;
174 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
175 struct evm_ima_xattr_data *xattr_value = NULL;
177 bool violation_check;
178 enum hash_algo hash_algo;
180 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
183 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
184 * bitmask based on the appraise/audit/measurement policy.
185 * Included is the appraise submask.
187 action = ima_get_action(inode, mask, func, &pcr);
188 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
189 (ima_policy_flag & IMA_MEASURE));
190 if (!action && !violation_check)
193 must_appraise = action & IMA_APPRAISE;
195 /* Is the appraise rule hook specific? */
196 if (action & IMA_FILE_APPRAISE)
202 iint = integrity_inode_get(inode);
207 if (violation_check) {
208 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
209 &pathbuf, &pathname);
216 /* Determine if already appraised/measured based on bitmask
217 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
218 * IMA_AUDIT, IMA_AUDITED)
220 iint->flags |= action;
221 action &= IMA_DO_MASK;
222 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
224 /* If target pcr is already measured, unset IMA_MEASURE action */
225 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
226 action ^= IMA_MEASURE;
228 /* Nothing to do, just return existing appraised status */
231 rc = ima_get_cache_status(iint, func);
235 template_desc = ima_template_desc_current();
236 if ((action & IMA_APPRAISE_SUBMASK) ||
237 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
238 /* read 'security.ima' */
239 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
241 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
243 rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
244 if (rc != 0 && rc != -EBADF && rc != -EINVAL)
247 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
248 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
250 if (action & IMA_MEASURE)
251 ima_store_measurement(iint, file, pathname,
252 xattr_value, xattr_len, pcr);
253 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
254 rc = ima_appraise_measurement(func, iint, file, pathname,
255 xattr_value, xattr_len, opened);
256 if (action & IMA_AUDIT)
257 ima_audit_measurement(iint, pathname);
259 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
262 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
263 !(iint->flags & IMA_NEW_FILE))
271 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
277 * ima_file_mmap - based on policy, collect/store measurement.
278 * @file: pointer to the file to be measured (May be NULL)
279 * @prot: contains the protection that will be applied by the kernel.
281 * Measure files being mmapped executable based on the ima_must_measure()
284 * On success return 0. On integrity appraisal error, assuming the file
285 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
287 int ima_file_mmap(struct file *file, unsigned long prot)
289 if (file && (prot & PROT_EXEC))
290 return process_measurement(file, NULL, 0, MAY_EXEC,
296 * ima_bprm_check - based on policy, collect/store measurement.
297 * @bprm: contains the linux_binprm structure
299 * The OS protects against an executable file, already open for write,
300 * from being executed in deny_write_access() and an executable file,
301 * already open for execute, from being modified in get_write_access().
302 * So we can be certain that what we verify and measure here is actually
303 * what is being executed.
305 * On success return 0. On integrity appraisal error, assuming the file
306 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
308 int ima_bprm_check(struct linux_binprm *bprm)
310 return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
315 * ima_path_check - based on policy, collect/store measurement.
316 * @file: pointer to the file to be measured
317 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
319 * Measure files based on the ima_must_measure() policy decision.
321 * On success return 0. On integrity appraisal error, assuming the file
322 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
324 int ima_file_check(struct file *file, int mask, int opened)
326 return process_measurement(file, NULL, 0,
327 mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
328 MAY_APPEND), FILE_CHECK, opened);
330 EXPORT_SYMBOL_GPL(ima_file_check);
333 * ima_post_path_mknod - mark as a new inode
334 * @dentry: newly created dentry
336 * Mark files created via the mknodat syscall as new, so that the
337 * file data can be written later.
339 void ima_post_path_mknod(struct dentry *dentry)
341 struct integrity_iint_cache *iint;
342 struct inode *inode = dentry->d_inode;
345 must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
349 iint = integrity_inode_get(inode);
351 iint->flags |= IMA_NEW_FILE;
355 * ima_read_file - pre-measure/appraise hook decision based on policy
356 * @file: pointer to the file to be measured/appraised/audit
357 * @read_id: caller identifier
359 * Permit reading a file based on policy. The policy rules are written
360 * in terms of the policy identifier. Appraising the integrity of
361 * a file requires a file descriptor.
363 * For permission return 0, otherwise return -EACCES.
365 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
367 bool sig_enforce = is_module_sig_enforced();
369 if (!file && read_id == READING_MODULE) {
370 if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
371 (ima_appraise & IMA_APPRAISE_ENFORCE))
372 return -EACCES; /* INTEGRITY_UNKNOWN */
373 return 0; /* We rely on module signature checking */
378 static int read_idmap[READING_MAX_ID] = {
379 [READING_FIRMWARE] = FIRMWARE_CHECK,
380 [READING_MODULE] = MODULE_CHECK,
381 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
382 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
383 [READING_POLICY] = POLICY_CHECK
387 * ima_post_read_file - in memory collect/appraise/audit measurement
388 * @file: pointer to the file to be measured/appraised/audit
389 * @buf: pointer to in memory file contents
390 * @size: size of in memory file contents
391 * @read_id: caller identifier
393 * Measure/appraise/audit in memory file based on policy. Policy rules
394 * are written in terms of a policy identifier.
396 * On success return 0. On integrity appraisal error, assuming the file
397 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
399 int ima_post_read_file(struct file *file, void *buf, loff_t size,
400 enum kernel_read_file_id read_id)
404 if (!file && read_id == READING_FIRMWARE) {
405 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
406 (ima_appraise & IMA_APPRAISE_ENFORCE))
407 return -EACCES; /* INTEGRITY_UNKNOWN */
411 if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
414 /* permit signed certs */
415 if (!file && read_id == READING_X509_CERTIFICATE)
418 if (!file || !buf || size == 0) { /* should never happen */
419 if (ima_appraise & IMA_APPRAISE_ENFORCE)
424 func = read_idmap[read_id] ?: FILE_CHECK;
425 return process_measurement(file, buf, size, MAY_READ, func, 0);
428 static int __init init_ima(void)
432 ima_init_template_list();
433 hash_setup(CONFIG_IMA_DEFAULT_HASH);
437 ima_update_policy_flag();
442 late_initcall(init_ima); /* Start IMA after the TPM is available */
444 MODULE_DESCRIPTION("Integrity Measurement Architecture");
445 MODULE_LICENSE("GPL");