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 (!IS_I_VERSION(inode) ||
131 (iint->version != inode->i_version) ||
132 (iint->flags & IMA_NEW_FILE)) {
133 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
134 iint->measured_pcrs = 0;
135 if (iint->flags & IMA_APPRAISE)
136 ima_update_xattr(iint, file);
143 * ima_file_free - called on __fput()
144 * @file: pointer to file structure being freed
146 * Flag files that changed, based on i_version
148 void ima_file_free(struct file *file)
150 struct inode *inode = file_inode(file);
151 struct integrity_iint_cache *iint;
153 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
156 iint = integrity_iint_find(inode);
160 ima_check_last_writer(iint, inode, file);
163 static int process_measurement(struct file *file, char *buf, loff_t size,
164 int mask, enum ima_hooks func, int opened)
166 struct inode *inode = file_inode(file);
167 struct integrity_iint_cache *iint = NULL;
168 struct ima_template_desc *template_desc;
169 char *pathbuf = NULL;
170 char filename[NAME_MAX];
171 const char *pathname = NULL;
172 int rc = -ENOMEM, action, must_appraise;
173 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
174 struct evm_ima_xattr_data *xattr_value = NULL;
176 bool violation_check;
177 enum hash_algo hash_algo;
179 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
182 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
183 * bitmask based on the appraise/audit/measurement policy.
184 * Included is the appraise submask.
186 action = ima_get_action(inode, mask, func, &pcr);
187 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
188 (ima_policy_flag & IMA_MEASURE));
189 if (!action && !violation_check)
192 must_appraise = action & IMA_APPRAISE;
194 /* Is the appraise rule hook specific? */
195 if (action & IMA_FILE_APPRAISE)
201 iint = integrity_inode_get(inode);
206 if (violation_check) {
207 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
208 &pathbuf, &pathname);
215 /* Determine if already appraised/measured based on bitmask
216 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
217 * IMA_AUDIT, IMA_AUDITED)
219 iint->flags |= action;
220 action &= IMA_DO_MASK;
221 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
223 /* If target pcr is already measured, unset IMA_MEASURE action */
224 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
225 action ^= IMA_MEASURE;
227 /* Nothing to do, just return existing appraised status */
230 rc = ima_get_cache_status(iint, func);
234 template_desc = ima_template_desc_current();
235 if ((action & IMA_APPRAISE_SUBMASK) ||
236 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
237 /* read 'security.ima' */
238 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
240 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
242 rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
243 if (rc != 0 && rc != -EBADF && rc != -EINVAL)
246 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
247 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
249 if (action & IMA_MEASURE)
250 ima_store_measurement(iint, file, pathname,
251 xattr_value, xattr_len, pcr);
252 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
253 rc = ima_appraise_measurement(func, iint, file, pathname,
254 xattr_value, xattr_len, opened);
255 if (action & IMA_AUDIT)
256 ima_audit_measurement(iint, pathname);
258 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
261 if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
262 !(iint->flags & IMA_NEW_FILE))
270 if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
276 * ima_file_mmap - based on policy, collect/store measurement.
277 * @file: pointer to the file to be measured (May be NULL)
278 * @prot: contains the protection that will be applied by the kernel.
280 * Measure files being mmapped executable based on the ima_must_measure()
283 * On success return 0. On integrity appraisal error, assuming the file
284 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
286 int ima_file_mmap(struct file *file, unsigned long prot)
288 if (file && (prot & PROT_EXEC))
289 return process_measurement(file, NULL, 0, MAY_EXEC,
295 * ima_bprm_check - based on policy, collect/store measurement.
296 * @bprm: contains the linux_binprm structure
298 * The OS protects against an executable file, already open for write,
299 * from being executed in deny_write_access() and an executable file,
300 * already open for execute, from being modified in get_write_access().
301 * So we can be certain that what we verify and measure here is actually
302 * what is being executed.
304 * On success return 0. On integrity appraisal error, assuming the file
305 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
307 int ima_bprm_check(struct linux_binprm *bprm)
309 return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
314 * ima_path_check - based on policy, collect/store measurement.
315 * @file: pointer to the file to be measured
316 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
318 * Measure files based on the ima_must_measure() policy decision.
320 * On success return 0. On integrity appraisal error, assuming the file
321 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
323 int ima_file_check(struct file *file, int mask, int opened)
325 return process_measurement(file, NULL, 0,
326 mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
327 MAY_APPEND), FILE_CHECK, opened);
329 EXPORT_SYMBOL_GPL(ima_file_check);
332 * ima_post_path_mknod - mark as a new inode
333 * @dentry: newly created dentry
335 * Mark files created via the mknodat syscall as new, so that the
336 * file data can be written later.
338 void ima_post_path_mknod(struct dentry *dentry)
340 struct integrity_iint_cache *iint;
341 struct inode *inode = dentry->d_inode;
344 must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
348 iint = integrity_inode_get(inode);
350 iint->flags |= IMA_NEW_FILE;
354 * ima_read_file - pre-measure/appraise hook decision based on policy
355 * @file: pointer to the file to be measured/appraised/audit
356 * @read_id: caller identifier
358 * Permit reading a file based on policy. The policy rules are written
359 * in terms of the policy identifier. Appraising the integrity of
360 * a file requires a file descriptor.
362 * For permission return 0, otherwise return -EACCES.
364 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
366 bool sig_enforce = is_module_sig_enforced();
368 if (!file && read_id == READING_MODULE) {
369 if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
370 (ima_appraise & IMA_APPRAISE_ENFORCE))
371 return -EACCES; /* INTEGRITY_UNKNOWN */
372 return 0; /* We rely on module signature checking */
377 static int read_idmap[READING_MAX_ID] = {
378 [READING_FIRMWARE] = FIRMWARE_CHECK,
379 [READING_MODULE] = MODULE_CHECK,
380 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
381 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
382 [READING_POLICY] = POLICY_CHECK
386 * ima_post_read_file - in memory collect/appraise/audit measurement
387 * @file: pointer to the file to be measured/appraised/audit
388 * @buf: pointer to in memory file contents
389 * @size: size of in memory file contents
390 * @read_id: caller identifier
392 * Measure/appraise/audit in memory file based on policy. Policy rules
393 * are written in terms of a policy identifier.
395 * On success return 0. On integrity appraisal error, assuming the file
396 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
398 int ima_post_read_file(struct file *file, void *buf, loff_t size,
399 enum kernel_read_file_id read_id)
403 if (!file && read_id == READING_FIRMWARE) {
404 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
405 (ima_appraise & IMA_APPRAISE_ENFORCE))
406 return -EACCES; /* INTEGRITY_UNKNOWN */
410 if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
413 /* permit signed certs */
414 if (!file && read_id == READING_X509_CERTIFICATE)
417 if (!file || !buf || size == 0) { /* should never happen */
418 if (ima_appraise & IMA_APPRAISE_ENFORCE)
423 func = read_idmap[read_id] ?: FILE_CHECK;
424 return process_measurement(file, buf, size, MAY_READ, func, 0);
427 static int __init init_ima(void)
431 ima_init_template_list();
432 hash_setup(CONFIG_IMA_DEFAULT_HASH);
436 ima_update_policy_flag();
441 late_initcall(init_ima); /* Start IMA after the TPM is available */
443 MODULE_DESCRIPTION("Integrity Measurement Architecture");
444 MODULE_LICENSE("GPL");