[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));

	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 (!iint_initialized || !S_ISREG(inode->i_mode))
		return;
	iint = ima_iint_find_get(inode);
	if (!iint)
		return;
	mutex_lock(&iint->mutex);
	if (!ima_initialized)
		goto out;
	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));

	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->readcount < 0) ||
	     (iint->writecount < 0)) &&
	    !ima_limit_imbalance(file)) {
		printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld)\n",
		       __func__, iint->readcount, iint->writecount);
		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 (!iint_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 = 0;

	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
e0d5bd2a EP	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
e950598d	150	if (!iint_initialized \|\| !S_ISREG(inode->i_mode))
8eb988c7 MZ	151	return;
	152	iint = ima_iint_find_get(inode);
	153	if (!iint)
	154	return;
	155	mutex_lock(&iint->mutex);
e950598d MZ	156	if (!ima_initialized)
e950598d MZ	157	goto out;
1e93d005	158	rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
8eb988c7 MZ	159	if (rc < 0)
	160	goto out;
	161
	162	if (mode & FMODE_WRITE) {
	163	ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
	164	goto out;
	165	}
	166	ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
	167	out:
	168	ima_inc_counts(iint, file->f_mode);
	169	mutex_unlock(&iint->mutex);
	170
	171	kref_put(&iint->refcount, iint_free);
	172	}
	173
e0d5bd2a EP	174	/*
	175	* Decrement ima counts
	176	*/
	177	static void ima_dec_counts(struct ima_iint_cache iint, struct inode inode,
1429b3ec	178	struct file *file)
e0d5bd2a	179	{
1429b3ec	180	mode_t mode = file->f_mode;
e0d5bd2a EP	181	BUG_ON(!mutex_is_locked(&iint->mutex));
e0d5bd2a EP	182
e0d5bd2a EP	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
b575156d	193	if (((iint->readcount < 0) \|\|
d1625436 MZ	194	(iint->writecount < 0)) &&
d1625436 MZ	195	!ima_limit_imbalance(file)) {
b575156d EP	196	printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld)\n",
b575156d EP	197	__func__, iint->readcount, iint->writecount);
e0d5bd2a EP	198	dump_stack();
	199	}
	200	}
	201
3323eec9 MZ	202	/**
	203	* ima_file_free - called on __fput()
	204	* @file: pointer to file structure being freed
	205	*
	206	* Flag files that changed, based on i_version;
	207	* and decrement the iint readcount/writecount.
	208	*/
	209	void ima_file_free(struct file *file)
	210	{
	211	struct inode *inode = file->f_dentry->d_inode;
	212	struct ima_iint_cache *iint;
	213
e950598d	214	if (!iint_initialized \|\| !S_ISREG(inode->i_mode))
3323eec9 MZ	215	return;
	216	iint = ima_iint_find_get(inode);
	217	if (!iint)
	218	return;
	219
	220	mutex_lock(&iint->mutex);
1429b3ec	221	ima_dec_counts(iint, inode, file);
3323eec9 MZ	222	mutex_unlock(&iint->mutex);
	223	kref_put(&iint->refcount, iint_free);
	224	}
	225
3323eec9 MZ	226	static int process_measurement(struct file file, const unsigned char filename,
	227	int mask, int function)
	228	{
	229	struct inode *inode = file->f_dentry->d_inode;
	230	struct ima_iint_cache *iint;
e950598d	231	int rc = 0;
3323eec9 MZ	232
	233	if (!ima_initialized \|\| !S_ISREG(inode->i_mode))
	234	return 0;
9353384e	235	iint = ima_iint_find_get(inode);
3323eec9 MZ	236	if (!iint)
	237	return -ENOMEM;
	238
	239	mutex_lock(&iint->mutex);
	240	rc = ima_must_measure(iint, inode, mask, function);
	241	if (rc != 0)
	242	goto out;
	243
	244	rc = ima_collect_measurement(iint, file);
	245	if (!rc)
	246	ima_store_measurement(iint, file, filename);
	247	out:
	248	mutex_unlock(&iint->mutex);
	249	kref_put(&iint->refcount, iint_free);
	250	return rc;
	251	}
	252
	253	/**
	254	* ima_file_mmap - based on policy, collect/store measurement.
	255	* @file: pointer to the file to be measured (May be NULL)
	256	* @prot: contains the protection that will be applied by the kernel.
	257	*
	258	* Measure files being mmapped executable based on the ima_must_measure()
	259	* policy decision.
	260	*
	261	* Return 0 on success, an error code on failure.
	262	* (Based on the results of appraise_measurement().)
	263	*/
	264	int ima_file_mmap(struct file *file, unsigned long prot)
	265	{
	266	int rc;
	267
	268	if (!file)
	269	return 0;
	270	if (prot & PROT_EXEC)
	271	rc = process_measurement(file, file->f_dentry->d_name.name,
	272	MAY_EXEC, FILE_MMAP);
	273	return 0;
	274	}
	275
	276	/**
	277	* ima_bprm_check - based on policy, collect/store measurement.
	278	* @bprm: contains the linux_binprm structure
	279	*
	280	* The OS protects against an executable file, already open for write,
	281	* from being executed in deny_write_access() and an executable file,
	282	* already open for execute, from being modified in get_write_access().
	283	* So we can be certain that what we verify and measure here is actually
	284	* what is being executed.
	285	*
	286	* Return 0 on success, an error code on failure.
	287	* (Based on the results of appraise_measurement().)
	288	*/
	289	int ima_bprm_check(struct linux_binprm *bprm)
	290	{
	291	int rc;
	292
	293	rc = process_measurement(bprm->file, bprm->filename,
	294	MAY_EXEC, BPRM_CHECK);
	295	return 0;
	296	}
	297
8eb988c7 MZ	298	/**
	299	* ima_path_check - based on policy, collect/store measurement.
	300	* @file: pointer to the file to be measured
	301	* @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
	302	*
	303	* Measure files based on the ima_must_measure() policy decision.
	304	*
	305	* Always return 0 and audit dentry_open failures.
	306	* (Return code will be based upon measurement appraisal.)
	307	*/
9bbb6cad	308	int ima_file_check(struct file *file, int mask)
8eb988c7 MZ	309	{
	310	int rc;
	311
	312	rc = process_measurement(file, file->f_dentry->d_name.name,
	313	mask & (MAY_READ \| MAY_WRITE \| MAY_EXEC),
1e93d005	314	FILE_CHECK);
8eb988c7 MZ	315	return 0;
8eb988c7 MZ	316	}
9bbb6cad	317	EXPORT_SYMBOL_GPL(ima_file_check);
8eb988c7	318
3323eec9 MZ	319	static int __init init_ima(void)
	320	{
	321	int error;
	322
3323eec9 MZ	323	error = ima_init();
	324	ima_initialized = 1;
	325	return error;
	326	}
	327
bab73937 MZ	328	static void __exit cleanup_ima(void)
	329	{
	330	ima_cleanup();
	331	}
	332
3323eec9 MZ	333	late_initcall(init_ima); /* Start IMA after the TPM is available */
	334
	335	MODULE_DESCRIPTION("Integrity Measurement Architecture");
	336	MODULE_LICENSE("GPL");