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);
38 struct ima_imbalance {
39 struct hlist_node node;
40 unsigned long fsmagic;
44 * ima_limit_imbalance - emit one imbalance message per filesystem type
46 * Maintain list of filesystem types that do not measure files properly.
47 * Return false if unknown, true if known.
49 static bool ima_limit_imbalance(struct file *file)
51 static DEFINE_SPINLOCK(ima_imbalance_lock);
52 static HLIST_HEAD(ima_imbalance_list);
54 struct super_block *sb = file->f_dentry->d_sb;
55 struct ima_imbalance *entry;
56 struct hlist_node *node;
60 hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
61 if (entry->fsmagic == sb->s_magic) {
70 entry = kmalloc(sizeof(*entry), GFP_NOFS);
73 entry->fsmagic = sb->s_magic;
74 spin_lock(&ima_imbalance_lock);
76 * we could have raced and something else might have added this fs
77 * to the list, but we don't really care
79 hlist_add_head_rcu(&entry->node, &ima_imbalance_list);
80 spin_unlock(&ima_imbalance_lock);
81 printk(KERN_INFO "IMA: unmeasured files on fsmagic: %lX\n",
88 * Update the counts given an fmode_t
90 static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
92 BUG_ON(!mutex_is_locked(&iint->mutex));
95 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
97 if (mode & FMODE_WRITE)
102 * Decrement ima counts
104 static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
107 mode_t mode = file->f_mode;
108 BUG_ON(!mutex_is_locked(&iint->mutex));
111 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
113 if (mode & FMODE_WRITE) {
115 if (iint->writecount == 0) {
116 if (iint->version != inode->i_version)
117 iint->flags &= ~IMA_MEASURED;
121 if (((iint->opencount < 0) ||
122 (iint->readcount < 0) ||
123 (iint->writecount < 0)) &&
124 !ima_limit_imbalance(file)) {
125 printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
126 __FUNCTION__, iint->readcount, iint->writecount,
133 * ima_file_free - called on __fput()
134 * @file: pointer to file structure being freed
136 * Flag files that changed, based on i_version;
137 * and decrement the iint readcount/writecount.
139 void ima_file_free(struct file *file)
141 struct inode *inode = file->f_dentry->d_inode;
142 struct ima_iint_cache *iint;
144 if (!ima_initialized || !S_ISREG(inode->i_mode))
146 iint = ima_iint_find_get(inode);
150 mutex_lock(&iint->mutex);
151 ima_dec_counts(iint, inode, file);
152 mutex_unlock(&iint->mutex);
153 kref_put(&iint->refcount, iint_free);
156 /* ima_read_write_check - reflect possible reading/writing errors in the PCR.
158 * When opening a file for read, if the file is already open for write,
159 * the file could change, resulting in a file measurement error.
161 * Opening a file for write, if the file is already open for read, results
162 * in a time of measure, time of use (ToMToU) error.
164 * In either case invalidate the PCR.
166 enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
167 static void ima_read_write_check(enum iint_pcr_error error,
168 struct ima_iint_cache *iint,
170 const unsigned char *filename)
174 if (iint->readcount > 0)
175 ima_add_violation(inode, filename, "invalid_pcr",
179 if (iint->writecount > 0)
180 ima_add_violation(inode, filename, "invalid_pcr",
186 static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
187 const unsigned char *filename)
191 ima_inc_counts(iint, file->f_mode);
193 rc = ima_collect_measurement(iint, file);
195 ima_store_measurement(iint, file, filename);
200 * ima_path_check - based on policy, collect/store measurement.
201 * @path: contains a pointer to the path to be measured
202 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
204 * Measure the file being open for readonly, based on the
205 * ima_must_measure() policy decision.
207 * Keep read/write counters for all files, but only
208 * invalidate the PCR for measured files:
209 * - Opening a file for write when already open for read,
210 * results in a time of measure, time of use (ToMToU) error.
211 * - Opening a file for read when already open for write,
212 * could result in a file measurement error.
214 * Always return 0 and audit dentry_open failures.
215 * (Return code will be based upon measurement appraisal.)
217 int ima_path_check(struct path *path, int mask)
219 struct inode *inode = path->dentry->d_inode;
220 struct ima_iint_cache *iint;
221 struct file *file = NULL;
224 if (!ima_initialized || !S_ISREG(inode->i_mode))
226 iint = ima_iint_find_get(inode);
230 mutex_lock(&iint->mutex);
232 rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
236 if ((mask & MAY_WRITE) || (mask == 0))
237 ima_read_write_check(TOMTOU, iint, inode,
238 path->dentry->d_name.name);
240 if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ)
243 ima_read_write_check(OPEN_WRITERS, iint, inode,
244 path->dentry->d_name.name);
245 if (!(iint->flags & IMA_MEASURED)) {
246 struct dentry *dentry = dget(path->dentry);
247 struct vfsmount *mnt = mntget(path->mnt);
249 file = dentry_open(dentry, mnt, O_RDONLY | O_LARGEFILE,
254 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
257 "dentry_open failed",
262 rc = get_path_measurement(iint, file, dentry->d_name.name);
265 mutex_unlock(&iint->mutex);
268 kref_put(&iint->refcount, iint_free);
271 EXPORT_SYMBOL_GPL(ima_path_check);
273 static int process_measurement(struct file *file, const unsigned char *filename,
274 int mask, int function)
276 struct inode *inode = file->f_dentry->d_inode;
277 struct ima_iint_cache *iint;
280 if (!ima_initialized || !S_ISREG(inode->i_mode))
282 iint = ima_iint_find_get(inode);
286 mutex_lock(&iint->mutex);
287 rc = ima_must_measure(iint, inode, mask, function);
291 rc = ima_collect_measurement(iint, file);
293 ima_store_measurement(iint, file, filename);
295 mutex_unlock(&iint->mutex);
296 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");