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",
88 /* ima_read_write_check - reflect possible reading/writing errors in the PCR.
90 * When opening a file for read, if the file is already open for write,
91 * the file could change, resulting in a file measurement error.
93 * Opening a file for write, if the file is already open for read, results
94 * in a time of measure, time of use (ToMToU) error.
96 * In either case invalidate the PCR.
98 enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
99 static void ima_read_write_check(enum iint_pcr_error error,
100 struct ima_iint_cache *iint,
102 const unsigned char *filename)
106 if (iint->readcount > 0)
107 ima_add_violation(inode, filename, "invalid_pcr",
111 if (iint->writecount > 0)
112 ima_add_violation(inode, filename, "invalid_pcr",
119 * Update the counts given an fmode_t
121 static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
123 BUG_ON(!mutex_is_locked(&iint->mutex));
125 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
127 if (mode & FMODE_WRITE)
132 * ima_counts_get - increment file counts
134 * Maintain read/write counters for all files, but only
135 * invalidate the PCR for measured files:
136 * - Opening a file for write when already open for read,
137 * results in a time of measure, time of use (ToMToU) error.
138 * - Opening a file for read when already open for write,
139 * could result in a file measurement error.
142 void ima_counts_get(struct file *file)
144 struct dentry *dentry = file->f_path.dentry;
145 struct inode *inode = dentry->d_inode;
146 fmode_t mode = file->f_mode;
147 struct ima_iint_cache *iint;
150 if (!iint_initialized || !S_ISREG(inode->i_mode))
152 iint = ima_iint_find_get(inode);
155 mutex_lock(&iint->mutex);
156 if (!ima_initialized)
158 rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
162 if (mode & FMODE_WRITE) {
163 ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
166 ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
168 ima_inc_counts(iint, file->f_mode);
169 mutex_unlock(&iint->mutex);
171 kref_put(&iint->refcount, iint_free);
175 * Decrement ima counts
177 static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
180 mode_t mode = file->f_mode;
183 BUG_ON(!mutex_is_locked(&iint->mutex));
185 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
186 if (unlikely(iint->readcount == 0))
190 if (mode & FMODE_WRITE) {
191 if (unlikely(iint->writecount == 0))
194 if (iint->writecount == 0) {
195 if (iint->version != inode->i_version)
196 iint->flags &= ~IMA_MEASURED;
200 if (dump && !ima_limit_imbalance(file)) {
201 printk(KERN_INFO "%s: open/free imbalance (r:%u w:%u)\n",
202 __func__, iint->readcount, iint->writecount);
208 * ima_file_free - called on __fput()
209 * @file: pointer to file structure being freed
211 * Flag files that changed, based on i_version;
212 * and decrement the iint readcount/writecount.
214 void ima_file_free(struct file *file)
216 struct inode *inode = file->f_dentry->d_inode;
217 struct ima_iint_cache *iint;
219 if (!iint_initialized || !S_ISREG(inode->i_mode))
221 iint = ima_iint_find_get(inode);
225 mutex_lock(&iint->mutex);
226 ima_dec_counts(iint, inode, file);
227 mutex_unlock(&iint->mutex);
228 kref_put(&iint->refcount, iint_free);
231 static int process_measurement(struct file *file, const unsigned char *filename,
232 int mask, int function)
234 struct inode *inode = file->f_dentry->d_inode;
235 struct ima_iint_cache *iint;
238 if (!ima_initialized || !S_ISREG(inode->i_mode))
240 iint = ima_iint_find_get(inode);
244 mutex_lock(&iint->mutex);
245 rc = ima_must_measure(iint, inode, mask, function);
249 rc = ima_collect_measurement(iint, file);
251 ima_store_measurement(iint, file, filename);
253 mutex_unlock(&iint->mutex);
254 kref_put(&iint->refcount, iint_free);
259 * ima_file_mmap - based on policy, collect/store measurement.
260 * @file: pointer to the file to be measured (May be NULL)
261 * @prot: contains the protection that will be applied by the kernel.
263 * Measure files being mmapped executable based on the ima_must_measure()
266 * Return 0 on success, an error code on failure.
267 * (Based on the results of appraise_measurement().)
269 int ima_file_mmap(struct file *file, unsigned long prot)
275 if (prot & PROT_EXEC)
276 rc = process_measurement(file, file->f_dentry->d_name.name,
277 MAY_EXEC, FILE_MMAP);
282 * ima_bprm_check - based on policy, collect/store measurement.
283 * @bprm: contains the linux_binprm structure
285 * The OS protects against an executable file, already open for write,
286 * from being executed in deny_write_access() and an executable file,
287 * already open for execute, from being modified in get_write_access().
288 * So we can be certain that what we verify and measure here is actually
289 * what is being executed.
291 * Return 0 on success, an error code on failure.
292 * (Based on the results of appraise_measurement().)
294 int ima_bprm_check(struct linux_binprm *bprm)
298 rc = process_measurement(bprm->file, bprm->filename,
299 MAY_EXEC, BPRM_CHECK);
304 * ima_path_check - based on policy, collect/store measurement.
305 * @file: pointer to the file to be measured
306 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
308 * Measure files based on the ima_must_measure() policy decision.
310 * Always return 0 and audit dentry_open failures.
311 * (Return code will be based upon measurement appraisal.)
313 int ima_file_check(struct file *file, int mask)
317 rc = process_measurement(file, file->f_dentry->d_name.name,
318 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
322 EXPORT_SYMBOL_GPL(ima_file_check);
324 static int __init init_ima(void)
333 static void __exit cleanup_ima(void)
338 late_initcall(init_ima); /* Start IMA after the TPM is available */
340 MODULE_DESCRIPTION("Integrity Measurement Architecture");
341 MODULE_LICENSE("GPL");