[deliverable/linux.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 "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>
	24
	25	#include "ima.h"
	26
	27	int ima_initialized;
	28
	29	char *ima_hash = "sha1";
	30	static int __init hash_setup(char *str)
	31	{
07ff7a0b MZ	32	if (strncmp(str, "md5", 3) == 0)
07ff7a0b MZ	33	ima_hash = "md5";
3323eec9 MZ	34	return 1;
	35	}
	36	__setup("ima_hash=", hash_setup);
	37
d1625436 MZ	38	struct ima_imbalance {
	39	struct hlist_node node;
	40	unsigned long fsmagic;
	41	};
	42
	43	/*
	44	* ima_limit_imbalance - emit one imbalance message per filesystem type
	45	*
	46	* Maintain list of filesystem types that do not measure files properly.
	47	* Return false if unknown, true if known.
	48	*/
	49	static bool ima_limit_imbalance(struct file *file)
	50	{
	51	static DEFINE_SPINLOCK(ima_imbalance_lock);
	52	static HLIST_HEAD(ima_imbalance_list);
	53
	54	struct super_block *sb = file->f_dentry->d_sb;
	55	struct ima_imbalance *entry;
	56	struct hlist_node *node;
	57	bool found = false;
	58
	59	rcu_read_lock();
	60	hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
	61	if (entry->fsmagic == sb->s_magic) {
	62	found = true;
	63	break;
	64	}
	65	}
	66	rcu_read_unlock();
	67	if (found)
	68	goto out;
	69
	70	entry = kmalloc(sizeof(*entry), GFP_NOFS);
	71	if (!entry)
	72	goto out;
	73	entry->fsmagic = sb->s_magic;
	74	spin_lock(&ima_imbalance_lock);
	75	/*
	76	* we could have raced and something else might have added this fs
	77	* to the list, but we don't really care
	78	*/
	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",
	82	entry->fsmagic);
	83	out:
	84	return found;
	85	}
	86
8eb988c7 MZ	87	/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
	88	*
	89	* When opening a file for read, if the file is already open for write,
	90	* the file could change, resulting in a file measurement error.
	91	*
	92	* Opening a file for write, if the file is already open for read, results
	93	* in a time of measure, time of use (ToMToU) error.
	94	*
	95	* In either case invalidate the PCR.
	96	*/
	97	enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
	98	static void ima_read_write_check(enum iint_pcr_error error,
	99	struct ima_iint_cache *iint,
	100	struct inode *inode,
	101	const unsigned char *filename)
	102	{
	103	switch (error) {
	104	case TOMTOU:
	105	if (iint->readcount > 0)
	106	ima_add_violation(inode, filename, "invalid_pcr",
	107	"ToMToU");
	108	break;
	109	case OPEN_WRITERS:
	110	if (iint->writecount > 0)
	111	ima_add_violation(inode, filename, "invalid_pcr",
	112	"open_writers");
	113	break;
	114	}
	115	}
	116
e0d5bd2a EP	117	/*
	118	* Update the counts given an fmode_t
	119	*/
	120	static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
	121	{
	122	BUG_ON(!mutex_is_locked(&iint->mutex));
	123
	124	iint->opencount++;
	125	if ((mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
	126	iint->readcount++;
	127	if (mode & FMODE_WRITE)
	128	iint->writecount++;
	129	}
	130
8eb988c7 MZ	131	/*
	132	* ima_counts_get - increment file counts
	133	*
	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.
	140	*
	141	*/
	142	void ima_counts_get(struct file *file)
	143	{
	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;
	148	int rc;
	149
	150	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	151	return;
	152	iint = ima_iint_find_get(inode);
	153	if (!iint)
	154	return;
	155	mutex_lock(&iint->mutex);
1e93d005	156	rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
8eb988c7 MZ	157	if (rc < 0)
	158	goto out;
	159
	160	if (mode & FMODE_WRITE) {
	161	ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
	162	goto out;
	163	}
	164	ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
	165	out:
	166	ima_inc_counts(iint, file->f_mode);
	167	mutex_unlock(&iint->mutex);
	168
	169	kref_put(&iint->refcount, iint_free);
	170	}
	171
e0d5bd2a EP	172	/*
	173	* Decrement ima counts
	174	*/
	175	static void ima_dec_counts(struct ima_iint_cache iint, struct inode inode,
1429b3ec	176	struct file *file)
e0d5bd2a	177	{
1429b3ec	178	mode_t mode = file->f_mode;
e0d5bd2a EP	179	BUG_ON(!mutex_is_locked(&iint->mutex));
	180
	181	iint->opencount--;
	182	if ((mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
	183	iint->readcount--;
	184	if (mode & FMODE_WRITE) {
	185	iint->writecount--;
	186	if (iint->writecount == 0) {
	187	if (iint->version != inode->i_version)
	188	iint->flags &= ~IMA_MEASURED;
	189	}
	190	}
	191
d1625436 MZ	192	if (((iint->opencount < 0) \|\|
	193	(iint->readcount < 0) \|\|
	194	(iint->writecount < 0)) &&
	195	!ima_limit_imbalance(file)) {
e0d5bd2a EP	196	printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
	197	__FUNCTION__, iint->readcount, iint->writecount,
	198	iint->opencount);
	199	dump_stack();
	200	}
	201	}
	202
3323eec9 MZ	203	/**
	204	* ima_file_free - called on __fput()
	205	* @file: pointer to file structure being freed
	206	*
	207	* Flag files that changed, based on i_version;
	208	* and decrement the iint readcount/writecount.
	209	*/
	210	void ima_file_free(struct file *file)
	211	{
	212	struct inode *inode = file->f_dentry->d_inode;
	213	struct ima_iint_cache *iint;
	214
	215	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	216	return;
	217	iint = ima_iint_find_get(inode);
	218	if (!iint)
	219	return;
	220
	221	mutex_lock(&iint->mutex);
1429b3ec	222	ima_dec_counts(iint, inode, file);
3323eec9 MZ	223	mutex_unlock(&iint->mutex);
	224	kref_put(&iint->refcount, iint_free);
	225	}
	226
3323eec9 MZ	227	static int process_measurement(struct file file, const unsigned char filename,
	228	int mask, int function)
	229	{
	230	struct inode *inode = file->f_dentry->d_inode;
	231	struct ima_iint_cache *iint;
	232	int rc;
	233
	234	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	235	return 0;
9353384e	236	iint = ima_iint_find_get(inode);
3323eec9 MZ	237	if (!iint)
	238	return -ENOMEM;
	239
	240	mutex_lock(&iint->mutex);
	241	rc = ima_must_measure(iint, inode, mask, function);
	242	if (rc != 0)
	243	goto out;
	244
	245	rc = ima_collect_measurement(iint, file);
	246	if (!rc)
	247	ima_store_measurement(iint, file, filename);
	248	out:
	249	mutex_unlock(&iint->mutex);
	250	kref_put(&iint->refcount, iint_free);
	251	return rc;
	252	}
	253
	254	/**
	255	* ima_file_mmap - based on policy, collect/store measurement.
	256	* @file: pointer to the file to be measured (May be NULL)
	257	* @prot: contains the protection that will be applied by the kernel.
	258	*
	259	* Measure files being mmapped executable based on the ima_must_measure()
	260	* policy decision.
	261	*
	262	* Return 0 on success, an error code on failure.
	263	* (Based on the results of appraise_measurement().)
	264	*/
	265	int ima_file_mmap(struct file *file, unsigned long prot)
	266	{
	267	int rc;
	268
	269	if (!file)
	270	return 0;
	271	if (prot & PROT_EXEC)
	272	rc = process_measurement(file, file->f_dentry->d_name.name,
	273	MAY_EXEC, FILE_MMAP);
	274	return 0;
	275	}
	276
	277	/**
	278	* ima_bprm_check - based on policy, collect/store measurement.
	279	* @bprm: contains the linux_binprm structure
	280	*
	281	* The OS protects against an executable file, already open for write,
	282	* from being executed in deny_write_access() and an executable file,
	283	* already open for execute, from being modified in get_write_access().
	284	* So we can be certain that what we verify and measure here is actually
	285	* what is being executed.
	286	*
	287	* Return 0 on success, an error code on failure.
	288	* (Based on the results of appraise_measurement().)
	289	*/
	290	int ima_bprm_check(struct linux_binprm *bprm)
	291	{
	292	int rc;
	293
	294	rc = process_measurement(bprm->file, bprm->filename,
	295	MAY_EXEC, BPRM_CHECK);
	296	return 0;
	297	}
	298
8eb988c7 MZ	299	/**
	300	* ima_path_check - based on policy, collect/store measurement.
	301	* @file: pointer to the file to be measured
	302	* @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
	303	*
	304	* Measure files based on the ima_must_measure() policy decision.
	305	*
	306	* Always return 0 and audit dentry_open failures.
	307	* (Return code will be based upon measurement appraisal.)
	308	*/
9bbb6cad	309	int ima_file_check(struct file *file, int mask)
8eb988c7 MZ	310	{
	311	int rc;
	312
	313	rc = process_measurement(file, file->f_dentry->d_name.name,
	314	mask & (MAY_READ \| MAY_WRITE \| MAY_EXEC),
1e93d005	315	FILE_CHECK);
8eb988c7 MZ	316	return 0;
8eb988c7 MZ	317	}
9bbb6cad	318	EXPORT_SYMBOL_GPL(ima_file_check);
8eb988c7	319
3323eec9 MZ	320	static int __init init_ima(void)
	321	{
	322	int error;
	323
3323eec9 MZ	324	error = ima_init();
	325	ima_initialized = 1;
	326	return error;
	327	}
	328
bab73937 MZ	329	static void __exit cleanup_ima(void)
	330	{
	331	ima_cleanup();
	332	}
	333
3323eec9 MZ	334	late_initcall(init_ima); /* Start IMA after the TPM is available */
	335
	336	MODULE_DESCRIPTION("Integrity Measurement Architecture");
	337	MODULE_LICENSE("GPL");