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;
59 for (i = 0; i < HASH_ALGO__LAST; i++) {
60 if (strcmp(str, hash_algo_name[i]) == 0) {
65 if (i == HASH_ALGO__LAST)
71 __setup("ima_hash=", hash_setup);
74 * ima_rdwr_violation_check
76 * Only invalidate the PCR for measured files:
77 * - Opening a file for write when already open for read,
78 * results in a time of measure, time of use (ToMToU) error.
79 * - Opening a file for read when already open for write,
80 * could result in a file measurement error.
83 static void ima_rdwr_violation_check(struct file *file,
84 struct integrity_iint_cache *iint,
87 const char **pathname)
89 struct inode *inode = file_inode(file);
90 char filename[NAME_MAX];
91 fmode_t mode = file->f_mode;
92 bool send_tomtou = false, send_writers = false;
94 if (mode & FMODE_WRITE) {
95 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
97 iint = integrity_iint_find(inode);
98 /* IMA_MEASURE is set from reader side */
99 if (iint && (iint->flags & IMA_MEASURE))
103 if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
107 if (!send_tomtou && !send_writers)
110 *pathname = ima_d_path(&file->f_path, pathbuf, filename);
113 ima_add_violation(file, *pathname, iint,
114 "invalid_pcr", "ToMToU");
116 ima_add_violation(file, *pathname, iint,
117 "invalid_pcr", "open_writers");
120 static void ima_check_last_writer(struct integrity_iint_cache *iint,
121 struct inode *inode, struct file *file)
123 fmode_t mode = file->f_mode;
125 if (!(mode & FMODE_WRITE))
129 if (atomic_read(&inode->i_writecount) == 1) {
130 if ((iint->version != inode->i_version) ||
131 (iint->flags & IMA_NEW_FILE)) {
132 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
133 iint->measured_pcrs = 0;
134 if (iint->flags & IMA_APPRAISE)
135 ima_update_xattr(iint, file);
142 * ima_file_free - called on __fput()
143 * @file: pointer to file structure being freed
145 * Flag files that changed, based on i_version
147 void ima_file_free(struct file *file)
149 struct inode *inode = file_inode(file);
150 struct integrity_iint_cache *iint;
152 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
155 iint = integrity_iint_find(inode);
159 ima_check_last_writer(iint, inode, file);
162 static int process_measurement(struct file *file, char *buf, loff_t size,
163 int mask, enum ima_hooks func, int opened)
165 struct inode *inode = file_inode(file);
166 struct integrity_iint_cache *iint = NULL;
167 struct ima_template_desc *template_desc;
168 char *pathbuf = NULL;
169 char filename[NAME_MAX];
170 const char *pathname = NULL;
171 int rc = -ENOMEM, action, must_appraise;
172 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
173 struct evm_ima_xattr_data *xattr_value = NULL;
175 bool violation_check;
176 enum hash_algo hash_algo;
178 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
181 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
182 * bitmask based on the appraise/audit/measurement policy.
183 * Included is the appraise submask.
185 action = ima_get_action(inode, mask, func, &pcr);
186 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
187 (ima_policy_flag & IMA_MEASURE));
188 if (!action && !violation_check)
191 must_appraise = action & IMA_APPRAISE;
193 /* Is the appraise rule hook specific? */
194 if (action & IMA_FILE_APPRAISE)
200 iint = integrity_inode_get(inode);
205 if (violation_check) {
206 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
207 &pathbuf, &pathname);
214 /* Determine if already appraised/measured based on bitmask
215 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
216 * IMA_AUDIT, IMA_AUDITED)
218 iint->flags |= action;
219 action &= IMA_DO_MASK;
220 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
222 /* If target pcr is already measured, unset IMA_MEASURE action */
223 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
224 action ^= IMA_MEASURE;
226 /* Nothing to do, just return existing appraised status */
229 rc = ima_get_cache_status(iint, func);
233 template_desc = ima_template_desc_current();
234 if ((action & IMA_APPRAISE_SUBMASK) ||
235 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
236 /* read 'security.ima' */
237 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
239 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
241 rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
242 if (rc != 0 && rc != -EBADF && rc != -EINVAL)
245 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
246 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
248 if (action & IMA_MEASURE)
249 ima_store_measurement(iint, file, pathname,
250 xattr_value, xattr_len, pcr);
251 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
252 rc = ima_appraise_measurement(func, iint, file, pathname,
253 xattr_value, xattr_len, opened);
254 if (action & IMA_AUDIT)
255 ima_audit_measurement(iint, pathname);
257 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
260 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
261 !(iint->flags & IMA_NEW_FILE))
269 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
275 * ima_file_mmap - based on policy, collect/store measurement.
276 * @file: pointer to the file to be measured (May be NULL)
277 * @prot: contains the protection that will be applied by the kernel.
279 * Measure files being mmapped executable based on the ima_must_measure()
282 * On success return 0. On integrity appraisal error, assuming the file
283 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
285 int ima_file_mmap(struct file *file, unsigned long prot)
287 if (file && (prot & PROT_EXEC))
288 return process_measurement(file, NULL, 0, MAY_EXEC,
294 * ima_bprm_check - based on policy, collect/store measurement.
295 * @bprm: contains the linux_binprm structure
297 * The OS protects against an executable file, already open for write,
298 * from being executed in deny_write_access() and an executable file,
299 * already open for execute, from being modified in get_write_access().
300 * So we can be certain that what we verify and measure here is actually
301 * what is being executed.
303 * On success return 0. On integrity appraisal error, assuming the file
304 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
306 int ima_bprm_check(struct linux_binprm *bprm)
308 return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
313 * ima_path_check - based on policy, collect/store measurement.
314 * @file: pointer to the file to be measured
315 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
317 * Measure files based on the ima_must_measure() policy decision.
319 * On success return 0. On integrity appraisal error, assuming the file
320 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
322 int ima_file_check(struct file *file, int mask, int opened)
324 return process_measurement(file, NULL, 0,
325 mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
326 MAY_APPEND), FILE_CHECK, opened);
328 EXPORT_SYMBOL_GPL(ima_file_check);
331 * ima_post_path_mknod - mark as a new inode
332 * @dentry: newly created dentry
334 * Mark files created via the mknodat syscall as new, so that the
335 * file data can be written later.
337 void ima_post_path_mknod(struct dentry *dentry)
339 struct integrity_iint_cache *iint;
340 struct inode *inode = dentry->d_inode;
343 must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
347 iint = integrity_inode_get(inode);
349 iint->flags |= IMA_NEW_FILE;
353 * ima_read_file - pre-measure/appraise hook decision based on policy
354 * @file: pointer to the file to be measured/appraised/audit
355 * @read_id: caller identifier
357 * Permit reading a file based on policy. The policy rules are written
358 * in terms of the policy identifier. Appraising the integrity of
359 * a file requires a file descriptor.
361 * For permission return 0, otherwise return -EACCES.
363 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
365 bool sig_enforce = is_module_sig_enforced();
367 if (!file && read_id == READING_MODULE) {
368 if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
369 (ima_appraise & IMA_APPRAISE_ENFORCE))
370 return -EACCES; /* INTEGRITY_UNKNOWN */
371 return 0; /* We rely on module signature checking */
376 static int read_idmap[READING_MAX_ID] = {
377 [READING_FIRMWARE] = FIRMWARE_CHECK,
378 [READING_MODULE] = MODULE_CHECK,
379 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
380 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
381 [READING_POLICY] = POLICY_CHECK
385 * ima_post_read_file - in memory collect/appraise/audit measurement
386 * @file: pointer to the file to be measured/appraised/audit
387 * @buf: pointer to in memory file contents
388 * @size: size of in memory file contents
389 * @read_id: caller identifier
391 * Measure/appraise/audit in memory file based on policy. Policy rules
392 * are written in terms of a policy identifier.
394 * On success return 0. On integrity appraisal error, assuming the file
395 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
397 int ima_post_read_file(struct file *file, void *buf, loff_t size,
398 enum kernel_read_file_id read_id)
402 if (!file && read_id == READING_FIRMWARE) {
403 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
404 (ima_appraise & IMA_APPRAISE_ENFORCE))
405 return -EACCES; /* INTEGRITY_UNKNOWN */
409 if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
412 /* permit signed certs */
413 if (!file && read_id == READING_X509_CERTIFICATE)
416 if (!file || !buf || size == 0) { /* should never happen */
417 if (ima_appraise & IMA_APPRAISE_ENFORCE)
422 func = read_idmap[read_id] ?: FILE_CHECK;
423 return process_measurement(file, buf, size, MAY_READ, func, 0);
426 static int __init init_ima(void)
430 ima_init_template_list();
431 hash_setup(CONFIG_IMA_DEFAULT_HASH);
435 ima_update_policy_flag();
440 late_initcall(init_ima); /* Start IMA after the TPM is available */
442 MODULE_DESCRIPTION("Integrity Measurement Architecture");
443 MODULE_LICENSE("GPL");