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>
29 char *ima_hash = "sha1";
30 static int __init hash_setup(char *str)
32 if (strncmp(str, "md5", 3) == 0)
36 __setup("ima_hash=", hash_setup);
39 * Update the counts given an fmode_t
41 static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
43 BUG_ON(!mutex_is_locked(&iint->mutex));
46 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
48 if (mode & FMODE_WRITE)
53 * Update the counts given open flags instead of fmode
55 static void ima_inc_counts_flags(struct ima_iint_cache *iint, int flags)
57 ima_inc_counts(iint, (__force fmode_t)((flags+1) & O_ACCMODE));
61 * Decrement ima counts
63 static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
66 BUG_ON(!mutex_is_locked(&iint->mutex));
69 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
71 if (mode & FMODE_WRITE) {
73 if (iint->writecount == 0) {
74 if (iint->version != inode->i_version)
75 iint->flags &= ~IMA_MEASURED;
79 if ((iint->opencount < 0) ||
80 (iint->readcount < 0) ||
81 (iint->writecount < 0)) {
88 printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
89 __FUNCTION__, iint->readcount, iint->writecount,
95 static void ima_dec_counts_flags(struct ima_iint_cache *iint,
96 struct inode *inode, int flags)
98 ima_dec_counts(iint, inode, (__force fmode_t)((flags+1) & O_ACCMODE));
102 * ima_file_free - called on __fput()
103 * @file: pointer to file structure being freed
105 * Flag files that changed, based on i_version;
106 * and decrement the iint readcount/writecount.
108 void ima_file_free(struct file *file)
110 struct inode *inode = file->f_dentry->d_inode;
111 struct ima_iint_cache *iint;
113 if (!ima_initialized || !S_ISREG(inode->i_mode))
115 iint = ima_iint_find_get(inode);
119 mutex_lock(&iint->mutex);
120 ima_dec_counts(iint, inode, file->f_mode);
121 mutex_unlock(&iint->mutex);
122 kref_put(&iint->refcount, iint_free);
125 /* ima_read_write_check - reflect possible reading/writing errors in the PCR.
127 * When opening a file for read, if the file is already open for write,
128 * the file could change, resulting in a file measurement error.
130 * Opening a file for write, if the file is already open for read, results
131 * in a time of measure, time of use (ToMToU) error.
133 * In either case invalidate the PCR.
135 enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
136 static void ima_read_write_check(enum iint_pcr_error error,
137 struct ima_iint_cache *iint,
139 const unsigned char *filename)
143 if (iint->readcount > 0)
144 ima_add_violation(inode, filename, "invalid_pcr",
148 if (iint->writecount > 0)
149 ima_add_violation(inode, filename, "invalid_pcr",
155 static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
156 const unsigned char *filename)
160 ima_inc_counts(iint, file->f_mode);
162 rc = ima_collect_measurement(iint, file);
164 ima_store_measurement(iint, file, filename);
169 * ima_path_check - based on policy, collect/store measurement.
170 * @path: contains a pointer to the path to be measured
171 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
173 * Measure the file being open for readonly, based on the
174 * ima_must_measure() policy decision.
176 * Keep read/write counters for all files, but only
177 * invalidate the PCR for measured files:
178 * - Opening a file for write when already open for read,
179 * results in a time of measure, time of use (ToMToU) error.
180 * - Opening a file for read when already open for write,
181 * could result in a file measurement error.
183 * Always return 0 and audit dentry_open failures.
184 * (Return code will be based upon measurement appraisal.)
186 int ima_path_check(struct path *path, int mask, int update_counts)
188 struct inode *inode = path->dentry->d_inode;
189 struct ima_iint_cache *iint;
190 struct file *file = NULL;
193 if (!ima_initialized || !S_ISREG(inode->i_mode))
195 iint = ima_iint_find_get(inode);
199 mutex_lock(&iint->mutex);
201 ima_inc_counts_flags(iint, mask);
203 rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
207 if ((mask & MAY_WRITE) || (mask == 0))
208 ima_read_write_check(TOMTOU, iint, inode,
209 path->dentry->d_name.name);
211 if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ)
214 ima_read_write_check(OPEN_WRITERS, iint, inode,
215 path->dentry->d_name.name);
216 if (!(iint->flags & IMA_MEASURED)) {
217 struct dentry *dentry = dget(path->dentry);
218 struct vfsmount *mnt = mntget(path->mnt);
220 file = dentry_open(dentry, mnt, O_RDONLY | O_LARGEFILE,
225 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
228 "dentry_open failed",
233 rc = get_path_measurement(iint, file, dentry->d_name.name);
236 mutex_unlock(&iint->mutex);
239 kref_put(&iint->refcount, iint_free);
242 EXPORT_SYMBOL_GPL(ima_path_check);
244 static int process_measurement(struct file *file, const unsigned char *filename,
245 int mask, int function)
247 struct inode *inode = file->f_dentry->d_inode;
248 struct ima_iint_cache *iint;
251 if (!ima_initialized || !S_ISREG(inode->i_mode))
253 iint = ima_iint_find_get(inode);
257 mutex_lock(&iint->mutex);
258 rc = ima_must_measure(iint, inode, mask, function);
262 rc = ima_collect_measurement(iint, file);
264 ima_store_measurement(iint, file, filename);
266 mutex_unlock(&iint->mutex);
267 kref_put(&iint->refcount, iint_free);
272 * ima_counts_put - decrement file counts
274 * File counts are incremented in ima_path_check. On file open
275 * error, such as ETXTBSY, decrement the counts to prevent
276 * unnecessary imbalance messages.
278 void ima_counts_put(struct path *path, int mask)
280 struct inode *inode = path->dentry->d_inode;
281 struct ima_iint_cache *iint;
283 /* The inode may already have been freed, freeing the iint
284 * with it. Verify the inode is not NULL before dereferencing
287 if (!ima_initialized || !inode || !S_ISREG(inode->i_mode))
289 iint = ima_iint_find_get(inode);
293 mutex_lock(&iint->mutex);
294 ima_dec_counts_flags(iint, inode, mask);
295 mutex_unlock(&iint->mutex);
297 kref_put(&iint->refcount, iint_free);
301 * ima_counts_get - increment file counts
303 * - for IPC shm and shmat file.
304 * - for nfsd exported files.
306 * Increment the counts for these files to prevent unnecessary
307 * imbalance messages.
309 void ima_counts_get(struct file *file)
311 struct inode *inode = file->f_dentry->d_inode;
312 struct ima_iint_cache *iint;
314 if (!ima_initialized || !S_ISREG(inode->i_mode))
316 iint = ima_iint_find_get(inode);
319 mutex_lock(&iint->mutex);
320 ima_inc_counts(iint, file->f_mode);
321 mutex_unlock(&iint->mutex);
323 kref_put(&iint->refcount, iint_free);
325 EXPORT_SYMBOL_GPL(ima_counts_get);
328 * ima_file_mmap - based on policy, collect/store measurement.
329 * @file: pointer to the file to be measured (May be NULL)
330 * @prot: contains the protection that will be applied by the kernel.
332 * Measure files being mmapped executable based on the ima_must_measure()
335 * Return 0 on success, an error code on failure.
336 * (Based on the results of appraise_measurement().)
338 int ima_file_mmap(struct file *file, unsigned long prot)
344 if (prot & PROT_EXEC)
345 rc = process_measurement(file, file->f_dentry->d_name.name,
346 MAY_EXEC, FILE_MMAP);
351 * ima_bprm_check - based on policy, collect/store measurement.
352 * @bprm: contains the linux_binprm structure
354 * The OS protects against an executable file, already open for write,
355 * from being executed in deny_write_access() and an executable file,
356 * already open for execute, from being modified in get_write_access().
357 * So we can be certain that what we verify and measure here is actually
358 * what is being executed.
360 * Return 0 on success, an error code on failure.
361 * (Based on the results of appraise_measurement().)
363 int ima_bprm_check(struct linux_binprm *bprm)
367 rc = process_measurement(bprm->file, bprm->filename,
368 MAY_EXEC, BPRM_CHECK);
372 static int __init init_ima(void)
376 ima_iintcache_init();
382 static void __exit cleanup_ima(void)
387 late_initcall(init_ima); /* Start IMA after the TPM is available */
389 MODULE_DESCRIPTION("Integrity Measurement Architecture");
390 MODULE_LICENSE("GPL");