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>
30 char *ima_hash = "sha1";
31 static int __init hash_setup(char *str)
33 if (strncmp(str, "md5", 3) == 0)
37 __setup("ima_hash=", hash_setup);
39 struct ima_imbalance {
40 struct hlist_node node;
41 unsigned long fsmagic;
45 * ima_limit_imbalance - emit one imbalance message per filesystem type
47 * Maintain list of filesystem types that do not measure files properly.
48 * Return false if unknown, true if known.
50 static bool ima_limit_imbalance(struct file *file)
52 static DEFINE_SPINLOCK(ima_imbalance_lock);
53 static HLIST_HEAD(ima_imbalance_list);
55 struct super_block *sb = file->f_dentry->d_sb;
56 struct ima_imbalance *entry;
57 struct hlist_node *node;
61 hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
62 if (entry->fsmagic == sb->s_magic) {
71 entry = kmalloc(sizeof(*entry), GFP_NOFS);
74 entry->fsmagic = sb->s_magic;
75 spin_lock(&ima_imbalance_lock);
77 * we could have raced and something else might have added this fs
78 * to the list, but we don't really care
80 hlist_add_head_rcu(&entry->node, &ima_imbalance_list);
81 spin_unlock(&ima_imbalance_lock);
82 printk(KERN_INFO "IMA: unmeasured files on fsmagic: %lX\n",
89 * Update the counts given an fmode_t
91 static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
93 assert_spin_locked(&iint->inode->i_lock);
95 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
100 * ima_counts_get - increment file counts
102 * Maintain read/write counters for all files, but only
103 * invalidate the PCR for measured files:
104 * - Opening a file for write when already open for read,
105 * results in a time of measure, time of use (ToMToU) error.
106 * - Opening a file for read when already open for write,
107 * could result in a file measurement error.
110 void ima_counts_get(struct file *file)
112 struct dentry *dentry = file->f_path.dentry;
113 struct inode *inode = dentry->d_inode;
114 fmode_t mode = file->f_mode;
115 struct ima_iint_cache *iint;
117 bool send_tomtou = false, send_writers = false;
119 if (!iint_initialized || !S_ISREG(inode->i_mode))
121 iint = ima_iint_find_get(inode);
124 mutex_lock(&iint->mutex);
125 spin_lock(&inode->i_lock);
127 if (!ima_initialized)
130 rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
134 if (mode & FMODE_WRITE) {
140 if (atomic_read(&inode->i_writecount) > 0)
143 ima_inc_counts(iint, file->f_mode);
144 spin_unlock(&inode->i_lock);
145 mutex_unlock(&iint->mutex);
146 kref_put(&iint->refcount, iint_free);
149 ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
152 ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
157 * Decrement ima counts
159 static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
162 mode_t mode = file->f_mode;
165 BUG_ON(!mutex_is_locked(&iint->mutex));
166 assert_spin_locked(&inode->i_lock);
168 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
169 if (unlikely(iint->readcount == 0))
173 if (mode & FMODE_WRITE) {
174 if (atomic_read(&inode->i_writecount) <= 0)
176 if (atomic_read(&inode->i_writecount) == 1 &&
177 iint->version != inode->i_version)
178 iint->flags &= ~IMA_MEASURED;
181 if (dump && !ima_limit_imbalance(file)) {
182 printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
183 __func__, iint->readcount);
189 * ima_file_free - called on __fput()
190 * @file: pointer to file structure being freed
192 * Flag files that changed, based on i_version;
193 * and decrement the iint readcount/writecount.
195 void ima_file_free(struct file *file)
197 struct inode *inode = file->f_dentry->d_inode;
198 struct ima_iint_cache *iint;
200 if (!iint_initialized || !S_ISREG(inode->i_mode))
202 iint = ima_iint_find_get(inode);
206 mutex_lock(&iint->mutex);
207 spin_lock(&inode->i_lock);
209 ima_dec_counts(iint, inode, file);
211 spin_unlock(&inode->i_lock);
212 mutex_unlock(&iint->mutex);
213 kref_put(&iint->refcount, iint_free);
216 static int process_measurement(struct file *file, const unsigned char *filename,
217 int mask, int function)
219 struct inode *inode = file->f_dentry->d_inode;
220 struct ima_iint_cache *iint;
223 if (!ima_initialized || !S_ISREG(inode->i_mode))
225 iint = ima_iint_find_get(inode);
229 mutex_lock(&iint->mutex);
230 rc = ima_must_measure(iint, inode, mask, function);
234 rc = ima_collect_measurement(iint, file);
236 ima_store_measurement(iint, file, filename);
238 mutex_unlock(&iint->mutex);
239 kref_put(&iint->refcount, iint_free);
244 * ima_file_mmap - based on policy, collect/store measurement.
245 * @file: pointer to the file to be measured (May be NULL)
246 * @prot: contains the protection that will be applied by the kernel.
248 * Measure files being mmapped executable based on the ima_must_measure()
251 * Return 0 on success, an error code on failure.
252 * (Based on the results of appraise_measurement().)
254 int ima_file_mmap(struct file *file, unsigned long prot)
260 if (prot & PROT_EXEC)
261 rc = process_measurement(file, file->f_dentry->d_name.name,
262 MAY_EXEC, FILE_MMAP);
267 * ima_bprm_check - based on policy, collect/store measurement.
268 * @bprm: contains the linux_binprm structure
270 * The OS protects against an executable file, already open for write,
271 * from being executed in deny_write_access() and an executable file,
272 * already open for execute, from being modified in get_write_access().
273 * So we can be certain that what we verify and measure here is actually
274 * what is being executed.
276 * Return 0 on success, an error code on failure.
277 * (Based on the results of appraise_measurement().)
279 int ima_bprm_check(struct linux_binprm *bprm)
283 rc = process_measurement(bprm->file, bprm->filename,
284 MAY_EXEC, BPRM_CHECK);
289 * ima_path_check - based on policy, collect/store measurement.
290 * @file: pointer to the file to be measured
291 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
293 * Measure files based on the ima_must_measure() policy decision.
295 * Always return 0 and audit dentry_open failures.
296 * (Return code will be based upon measurement appraisal.)
298 int ima_file_check(struct file *file, int mask)
302 rc = process_measurement(file, file->f_dentry->d_name.name,
303 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
307 EXPORT_SYMBOL_GPL(ima_file_check);
309 static int __init init_ima(void)
318 static void __exit cleanup_ima(void)
323 late_initcall(init_ima); /* Start IMA after the TPM is available */
325 MODULE_DESCRIPTION("Integrity Measurement Architecture");
326 MODULE_LICENSE("GPL");