[net-next-2.6.git] / security / integrity / ima / ima_main.c

/*
 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
 *
 * Authors:
 * Reiner Sailer <sailer@watson.ibm.com>
 * Serge Hallyn <serue@us.ibm.com>
 * Kylene Hall <kylene@us.ibm.com>
 * Mimi Zohar <zohar@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 * File: ima_main.c
 *	implements the IMA hooks: ima_bprm_check, ima_file_mmap,
 *	and ima_file_check.
 */
#include <linux/module.h>
#include <linux/file.h>
#include <linux/binfmts.h>
#include <linux/mount.h>
#include <linux/mman.h>
#include <linux/slab.h>

#include "ima.h"

int ima_initialized;

char *ima_hash = "sha1";
static int __init hash_setup(char *str)
{
	if (strncmp(str, "md5", 3) == 0)
		ima_hash = "md5";
	return 1;
}
__setup("ima_hash=", hash_setup);

struct ima_imbalance {
	struct hlist_node node;
	unsigned long fsmagic;
};

/*
 * ima_limit_imbalance - emit one imbalance message per filesystem type
 *
 * Maintain list of filesystem types that do not measure files properly.
 * Return false if unknown, true if known.
 */
static bool ima_limit_imbalance(struct file *file)
{
	static DEFINE_SPINLOCK(ima_imbalance_lock);
	static HLIST_HEAD(ima_imbalance_list);

	struct super_block *sb = file->f_dentry->d_sb;
	struct ima_imbalance *entry;
	struct hlist_node *node;
	bool found = false;

	rcu_read_lock();
	hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
		if (entry->fsmagic == sb->s_magic) {
			found = true;
			break;
		}
	}
	rcu_read_unlock();
	if (found)
		goto out;

	entry = kmalloc(sizeof(*entry), GFP_NOFS);
	if (!entry)
		goto out;
	entry->fsmagic = sb->s_magic;
	spin_lock(&ima_imbalance_lock);
	/*
	 * we could have raced and something else might have added this fs
	 * to the list, but we don't really care
	 */
	hlist_add_head_rcu(&entry->node, &ima_imbalance_list);
	spin_unlock(&ima_imbalance_lock);
	printk(KERN_INFO "IMA: unmeasured files on fsmagic: %lX\n",
	       entry->fsmagic);
out:
	return found;
}

/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
 *
 * When opening a file for read, if the file is already open for write,
 * the file could change, resulting in a file measurement error.
 *
 * Opening a file for write, if the file is already open for read, results
 * in a time of measure, time of use (ToMToU) error.
 *
 * In either case invalidate the PCR.
 */
enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
static void ima_read_write_check(enum iint_pcr_error error,
				 struct ima_iint_cache *iint,
				 struct inode *inode,
				 const unsigned char *filename)
{
	switch (error) {
	case TOMTOU:
		if (iint->readcount > 0)
			ima_add_violation(inode, filename, "invalid_pcr",
					  "ToMToU");
		break;
	case OPEN_WRITERS:
		if (iint->writecount > 0)
			ima_add_violation(inode, filename, "invalid_pcr",
					  "open_writers");
		break;
	}
}

/*
 * Update the counts given an fmode_t
 */
static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
{
	BUG_ON(!mutex_is_locked(&iint->mutex));

	iint->opencount++;
	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		iint->readcount++;
	if (mode & FMODE_WRITE)
		iint->writecount++;
}

/*
 * ima_counts_get - increment file counts
 *
 * Maintain read/write counters for all files, but only
 * invalidate the PCR for measured files:
 * 	- Opening a file for write when already open for read,
 *	  results in a time of measure, time of use (ToMToU) error.
 *	- Opening a file for read when already open for write,
 * 	  could result in a file measurement error.
 *
 */
void ima_counts_get(struct file *file)
{
	struct dentry *dentry = file->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	fmode_t mode = file->f_mode;
	struct ima_iint_cache *iint;
	int rc;

	if (!ima_initialized || !S_ISREG(inode->i_mode))
		return;
	iint = ima_iint_find_get(inode);
	if (!iint)
		return;
	mutex_lock(&iint->mutex);
	rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
	if (rc < 0)
		goto out;

	if (mode & FMODE_WRITE) {
		ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
		goto out;
	}
	ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
out:
	ima_inc_counts(iint, file->f_mode);
	mutex_unlock(&iint->mutex);

	kref_put(&iint->refcount, iint_free);
}

/*
 * Decrement ima counts
 */
static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
			   struct file *file)
{
	mode_t mode = file->f_mode;
	BUG_ON(!mutex_is_locked(&iint->mutex));

	iint->opencount--;
	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		iint->readcount--;
	if (mode & FMODE_WRITE) {
		iint->writecount--;
		if (iint->writecount == 0) {
			if (iint->version != inode->i_version)
				iint->flags &= ~IMA_MEASURED;
		}
	}

	if (((iint->opencount < 0) ||
	     (iint->readcount < 0) ||
	     (iint->writecount < 0)) &&
	    !ima_limit_imbalance(file)) {
		printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
		       __FUNCTION__, iint->readcount, iint->writecount,
		       iint->opencount);
		dump_stack();
	}
}

/**
 * ima_file_free - called on __fput()
 * @file: pointer to file structure being freed
 *
 * Flag files that changed, based on i_version;
 * and decrement the iint readcount/writecount.
 */
void ima_file_free(struct file *file)
{
	struct inode *inode = file->f_dentry->d_inode;
	struct ima_iint_cache *iint;

	if (!ima_initialized || !S_ISREG(inode->i_mode))
		return;
	iint = ima_iint_find_get(inode);
	if (!iint)
		return;

	mutex_lock(&iint->mutex);
	ima_dec_counts(iint, inode, file);
	mutex_unlock(&iint->mutex);
	kref_put(&iint->refcount, iint_free);
}

static int process_measurement(struct file *file, const unsigned char *filename,
			       int mask, int function)
{
	struct inode *inode = file->f_dentry->d_inode;
	struct ima_iint_cache *iint;
	int rc;

	if (!ima_initialized || !S_ISREG(inode->i_mode))
		return 0;
	iint = ima_iint_find_get(inode);
	if (!iint)
		return -ENOMEM;

	mutex_lock(&iint->mutex);
	rc = ima_must_measure(iint, inode, mask, function);
	if (rc != 0)
		goto out;

	rc = ima_collect_measurement(iint, file);
	if (!rc)
		ima_store_measurement(iint, file, filename);
out:
	mutex_unlock(&iint->mutex);
	kref_put(&iint->refcount, iint_free);
	return rc;
}

/**
 * ima_file_mmap - based on policy, collect/store measurement.
 * @file: pointer to the file to be measured (May be NULL)
 * @prot: contains the protection that will be applied by the kernel.
 *
 * Measure files being mmapped executable based on the ima_must_measure()
 * policy decision.
 *
 * Return 0 on success, an error code on failure.
 * (Based on the results of appraise_measurement().)
 */
int ima_file_mmap(struct file *file, unsigned long prot)
{
	int rc;

	if (!file)
		return 0;
	if (prot & PROT_EXEC)
		rc = process_measurement(file, file->f_dentry->d_name.name,
					 MAY_EXEC, FILE_MMAP);
	return 0;
}

/**
 * ima_bprm_check - based on policy, collect/store measurement.
 * @bprm: contains the linux_binprm structure
 *
 * The OS protects against an executable file, already open for write,
 * from being executed in deny_write_access() and an executable file,
 * already open for execute, from being modified in get_write_access().
 * So we can be certain that what we verify and measure here is actually
 * what is being executed.
 *
 * Return 0 on success, an error code on failure.
 * (Based on the results of appraise_measurement().)
 */
int ima_bprm_check(struct linux_binprm *bprm)
{
	int rc;

	rc = process_measurement(bprm->file, bprm->filename,
				 MAY_EXEC, BPRM_CHECK);
	return 0;
}

/**
 * ima_path_check - based on policy, collect/store measurement.
 * @file: pointer to the file to be measured
 * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
 *
 * Measure files based on the ima_must_measure() policy decision.
 *
 * Always return 0 and audit dentry_open failures.
 * (Return code will be based upon measurement appraisal.)
 */
int ima_file_check(struct file *file, int mask)
{
	int rc;

	rc = process_measurement(file, file->f_dentry->d_name.name,
				 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
				 FILE_CHECK);
	return 0;
}
EXPORT_SYMBOL_GPL(ima_file_check);

static int __init init_ima(void)
{
	int error;

	error = ima_init();
	ima_initialized = 1;
	return error;
}

static void __exit cleanup_ima(void)
{
	ima_cleanup();
}

late_initcall(init_ima);	/* Start IMA after the TPM is available */

MODULE_DESCRIPTION("Integrity Measurement Architecture");
MODULE_LICENSE("GPL");
Commit	Line	Data
3323eec9 MZ	1	/*
	2	* Copyright (C) 2005,2006,2007,2008 IBM Corporation
	3	*
	4	* Authors:
	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>
	9	*
	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
	13	* License.
	14	*
	15	* File: ima_main.c
e0d5bd2a	16	* implements the IMA hooks: ima_bprm_check, ima_file_mmap,
9bbb6cad	17	* and ima_file_check.
3323eec9 MZ	18	*/
	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>
5a0e3ad6	24	#include <linux/slab.h>
3323eec9 MZ	25
	26	#include "ima.h"
	27
	28	int ima_initialized;
	29
	30	char *ima_hash = "sha1";
	31	static int __init hash_setup(char *str)
	32	{
07ff7a0b MZ	33	if (strncmp(str, "md5", 3) == 0)
07ff7a0b MZ	34	ima_hash = "md5";
3323eec9 MZ	35	return 1;
	36	}
	37	__setup("ima_hash=", hash_setup);
	38
d1625436 MZ	39	struct ima_imbalance {
	40	struct hlist_node node;
	41	unsigned long fsmagic;
	42	};
	43
	44	/*
	45	* ima_limit_imbalance - emit one imbalance message per filesystem type
	46	*
	47	* Maintain list of filesystem types that do not measure files properly.
	48	* Return false if unknown, true if known.
	49	*/
	50	static bool ima_limit_imbalance(struct file *file)
	51	{
	52	static DEFINE_SPINLOCK(ima_imbalance_lock);
	53	static HLIST_HEAD(ima_imbalance_list);
	54
	55	struct super_block *sb = file->f_dentry->d_sb;
	56	struct ima_imbalance *entry;
	57	struct hlist_node *node;
	58	bool found = false;
	59
	60	rcu_read_lock();
	61	hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
	62	if (entry->fsmagic == sb->s_magic) {
	63	found = true;
	64	break;
	65	}
	66	}
	67	rcu_read_unlock();
	68	if (found)
	69	goto out;
	70
	71	entry = kmalloc(sizeof(*entry), GFP_NOFS);
	72	if (!entry)
	73	goto out;
	74	entry->fsmagic = sb->s_magic;
	75	spin_lock(&ima_imbalance_lock);
	76	/*
	77	* we could have raced and something else might have added this fs
	78	* to the list, but we don't really care
	79	*/
	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",
	83	entry->fsmagic);
	84	out:
	85	return found;
	86	}
	87
8eb988c7 MZ	88	/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
	89	*
	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.
	92	*
	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.
	95	*
	96	* In either case invalidate the PCR.
	97	*/
	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,
	101	struct inode *inode,
	102	const unsigned char *filename)
	103	{
	104	switch (error) {
	105	case TOMTOU:
	106	if (iint->readcount > 0)
	107	ima_add_violation(inode, filename, "invalid_pcr",
	108	"ToMToU");
	109	break;
	110	case OPEN_WRITERS:
	111	if (iint->writecount > 0)
	112	ima_add_violation(inode, filename, "invalid_pcr",
	113	"open_writers");
	114	break;
	115	}
	116	}
	117
e0d5bd2a EP	118	/*
	119	* Update the counts given an fmode_t
	120	*/
	121	static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
	122	{
	123	BUG_ON(!mutex_is_locked(&iint->mutex));
	124
	125	iint->opencount++;
	126	if ((mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
	127	iint->readcount++;
	128	if (mode & FMODE_WRITE)
	129	iint->writecount++;
	130	}
	131
8eb988c7 MZ	132	/*
	133	* ima_counts_get - increment file counts
	134	*
	135	* Maintain read/write counters for all files, but only
	136	* invalidate the PCR for measured files:
	137	* - Opening a file for write when already open for read,
	138	* results in a time of measure, time of use (ToMToU) error.
	139	* - Opening a file for read when already open for write,
	140	* could result in a file measurement error.
	141	*
	142	*/
	143	void ima_counts_get(struct file *file)
	144	{
	145	struct dentry *dentry = file->f_path.dentry;
	146	struct inode *inode = dentry->d_inode;
	147	fmode_t mode = file->f_mode;
	148	struct ima_iint_cache *iint;
	149	int rc;
	150
	151	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	152	return;
	153	iint = ima_iint_find_get(inode);
	154	if (!iint)
	155	return;
	156	mutex_lock(&iint->mutex);
1e93d005	157	rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
8eb988c7 MZ	158	if (rc < 0)
	159	goto out;
	160
	161	if (mode & FMODE_WRITE) {
	162	ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
	163	goto out;
	164	}
	165	ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
	166	out:
	167	ima_inc_counts(iint, file->f_mode);
	168	mutex_unlock(&iint->mutex);
	169
	170	kref_put(&iint->refcount, iint_free);
	171	}
	172
e0d5bd2a EP	173	/*
	174	* Decrement ima counts
	175	*/
	176	static void ima_dec_counts(struct ima_iint_cache iint, struct inode inode,
1429b3ec	177	struct file *file)
e0d5bd2a	178	{
1429b3ec	179	mode_t mode = file->f_mode;
e0d5bd2a EP	180	BUG_ON(!mutex_is_locked(&iint->mutex));
	181
	182	iint->opencount--;
	183	if ((mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
	184	iint->readcount--;
	185	if (mode & FMODE_WRITE) {
	186	iint->writecount--;
	187	if (iint->writecount == 0) {
	188	if (iint->version != inode->i_version)
	189	iint->flags &= ~IMA_MEASURED;
	190	}
	191	}
	192
d1625436 MZ	193	if (((iint->opencount < 0) \|\|
	194	(iint->readcount < 0) \|\|
	195	(iint->writecount < 0)) &&
	196	!ima_limit_imbalance(file)) {
e0d5bd2a EP	197	printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
	198	__FUNCTION__, iint->readcount, iint->writecount,
	199	iint->opencount);
	200	dump_stack();
	201	}
	202	}
	203
3323eec9 MZ	204	/**
	205	* ima_file_free - called on __fput()
	206	* @file: pointer to file structure being freed
	207	*
	208	* Flag files that changed, based on i_version;
	209	* and decrement the iint readcount/writecount.
	210	*/
	211	void ima_file_free(struct file *file)
	212	{
	213	struct inode *inode = file->f_dentry->d_inode;
	214	struct ima_iint_cache *iint;
	215
	216	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	217	return;
	218	iint = ima_iint_find_get(inode);
	219	if (!iint)
	220	return;
	221
	222	mutex_lock(&iint->mutex);
1429b3ec	223	ima_dec_counts(iint, inode, file);
3323eec9 MZ	224	mutex_unlock(&iint->mutex);
	225	kref_put(&iint->refcount, iint_free);
	226	}
	227
3323eec9 MZ	228	static int process_measurement(struct file file, const unsigned char filename,
	229	int mask, int function)
	230	{
	231	struct inode *inode = file->f_dentry->d_inode;
	232	struct ima_iint_cache *iint;
	233	int rc;
	234
	235	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	236	return 0;
9353384e	237	iint = ima_iint_find_get(inode);
3323eec9 MZ	238	if (!iint)
	239	return -ENOMEM;
	240
	241	mutex_lock(&iint->mutex);
	242	rc = ima_must_measure(iint, inode, mask, function);
	243	if (rc != 0)
	244	goto out;
	245
	246	rc = ima_collect_measurement(iint, file);
	247	if (!rc)
	248	ima_store_measurement(iint, file, filename);
	249	out:
	250	mutex_unlock(&iint->mutex);
	251	kref_put(&iint->refcount, iint_free);
	252	return rc;
	253	}
	254
	255	/**
	256	* ima_file_mmap - based on policy, collect/store measurement.
	257	* @file: pointer to the file to be measured (May be NULL)
	258	* @prot: contains the protection that will be applied by the kernel.
	259	*
	260	* Measure files being mmapped executable based on the ima_must_measure()
	261	* policy decision.
	262	*
	263	* Return 0 on success, an error code on failure.
	264	* (Based on the results of appraise_measurement().)
	265	*/
	266	int ima_file_mmap(struct file *file, unsigned long prot)
	267	{
	268	int rc;
	269
	270	if (!file)
	271	return 0;
	272	if (prot & PROT_EXEC)
	273	rc = process_measurement(file, file->f_dentry->d_name.name,
	274	MAY_EXEC, FILE_MMAP);
	275	return 0;
	276	}
	277
	278	/**
	279	* ima_bprm_check - based on policy, collect/store measurement.
	280	* @bprm: contains the linux_binprm structure
	281	*
	282	* The OS protects against an executable file, already open for write,
	283	* from being executed in deny_write_access() and an executable file,
	284	* already open for execute, from being modified in get_write_access().
	285	* So we can be certain that what we verify and measure here is actually
	286	* what is being executed.
	287	*
	288	* Return 0 on success, an error code on failure.
	289	* (Based on the results of appraise_measurement().)
	290	*/
	291	int ima_bprm_check(struct linux_binprm *bprm)
	292	{
	293	int rc;
	294
	295	rc = process_measurement(bprm->file, bprm->filename,
	296	MAY_EXEC, BPRM_CHECK);
	297	return 0;
	298	}
	299
8eb988c7 MZ	300	/**
	301	* ima_path_check - based on policy, collect/store measurement.
	302	* @file: pointer to the file to be measured
	303	* @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
	304	*
	305	* Measure files based on the ima_must_measure() policy decision.
	306	*
	307	* Always return 0 and audit dentry_open failures.
	308	* (Return code will be based upon measurement appraisal.)
	309	*/
9bbb6cad	310	int ima_file_check(struct file *file, int mask)
8eb988c7 MZ	311	{
	312	int rc;
	313
	314	rc = process_measurement(file, file->f_dentry->d_name.name,
	315	mask & (MAY_READ \| MAY_WRITE \| MAY_EXEC),
1e93d005	316	FILE_CHECK);
8eb988c7 MZ	317	return 0;
8eb988c7 MZ	318	}
9bbb6cad	319	EXPORT_SYMBOL_GPL(ima_file_check);
8eb988c7	320
3323eec9 MZ	321	static int __init init_ima(void)
	322	{
	323	int error;
	324
3323eec9 MZ	325	error = ima_init();
	326	ima_initialized = 1;
	327	return error;
	328	}
	329
bab73937 MZ	330	static void __exit cleanup_ima(void)
	331	{
	332	ima_cleanup();
	333	}
	334
3323eec9 MZ	335	late_initcall(init_ima); /* Start IMA after the TPM is available */
	336
	337	MODULE_DESCRIPTION("Integrity Measurement Architecture");
	338	MODULE_LICENSE("GPL");