security/integrity/ima/ima_main.c - SHIFTPHONES/mainline/linux - Gitiles

 /*
  * Integrity Measurement Architecture
  *
  * 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.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/init.h>
 #include <linux/file.h>
 #include <linux/binfmts.h>
 #include <linux/mount.h>
 #include <linux/mman.h>
 #include <linux/slab.h>
 #include <linux/xattr.h>
 #include <linux/ima.h>
 #include <linux/iversion.h>
 #include <linux/fs.h>

 #include "ima.h"

 #ifdef CONFIG_IMA_APPRAISE
 int ima_appraise = IMA_APPRAISE_ENFORCE;
 #else
 int ima_appraise;
 #endif

 int ima_hash_algo = HASH_ALGO_SHA1;
 static int hash_setup_done;

 static int __init hash_setup(char *str)
 {
 	struct ima_template_desc *template_desc = ima_template_desc_current();
 	int i;

 	if (hash_setup_done)
 		return 1;

 	if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
 		if (strncmp(str, "sha1", 4) == 0)
 			ima_hash_algo = HASH_ALGO_SHA1;
 		else if (strncmp(str, "md5", 3) == 0)
 			ima_hash_algo = HASH_ALGO_MD5;
 		else
 			return 1;
 		goto out;
 	}

 	i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
 	if (i < 0)
 		return 1;

 	ima_hash_algo = i;
 out:
 	hash_setup_done = 1;
 	return 1;
 }
 __setup("ima_hash=", hash_setup);

 /*
  * ima_rdwr_violation_check
  *
  * 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.
  *
  */
 static void ima_rdwr_violation_check(struct file *file,
 				     struct integrity_iint_cache *iint,
 				     int must_measure,
 				     char **pathbuf,
 				     const char **pathname,
 				     char *filename)
 {
 	struct inode *inode = file_inode(file);
 	fmode_t mode = file->f_mode;
 	bool send_tomtou = false, send_writers = false;

 	if (mode & FMODE_WRITE) {
 		if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
 			if (!iint)
 				iint = integrity_iint_find(inode);
 			/* IMA_MEASURE is set from reader side */
 			if (iint && test_bit(IMA_MUST_MEASURE,
 						&iint->atomic_flags))
 				send_tomtou = true;
 		}
 	} else {
 		if (must_measure)
 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
 		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
 			send_writers = true;
 	}

 	if (!send_tomtou && !send_writers)
 		return;

 	*pathname = ima_d_path(&file->f_path, pathbuf, filename);

 	if (send_tomtou)
 		ima_add_violation(file, *pathname, iint,
 				  "invalid_pcr", "ToMToU");
 	if (send_writers)
 		ima_add_violation(file, *pathname, iint,
 				  "invalid_pcr", "open_writers");
 }

 static void ima_check_last_writer(struct integrity_iint_cache *iint,
 				  struct inode *inode, struct file *file)
 {
 	fmode_t mode = file->f_mode;
 	bool update;

 	if (!(mode & FMODE_WRITE))
 		return;

 	mutex_lock(&iint->mutex);
 	if (atomic_read(&inode->i_writecount) == 1) {
 		update = test_and_clear_bit(IMA_UPDATE_XATTR,
 					    &iint->atomic_flags);
 		if (!IS_I_VERSION(inode) ||
 		    !inode_eq_iversion(inode, iint->version) ||
 		    (iint->flags & IMA_NEW_FILE)) {
 			iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
 			iint->measured_pcrs = 0;
 			if (update)
 				ima_update_xattr(iint, file);
 		}
 	}
 	mutex_unlock(&iint->mutex);
 }

 /**
  * ima_file_free - called on __fput()
  * @file: pointer to file structure being freed
  *
  * Flag files that changed, based on i_version
  */
 void ima_file_free(struct file *file)
 {
 	struct inode *inode = file_inode(file);
 	struct integrity_iint_cache *iint;

 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return;

 	iint = integrity_iint_find(inode);
 	if (!iint)
 		return;

 	ima_check_last_writer(iint, inode, file);
 }

 static int process_measurement(struct file *file, const struct cred *cred,
 			       u32 secid, char *buf, loff_t size, int mask,
 			       enum ima_hooks func)
 {
 	struct inode *inode = file_inode(file);
 	struct integrity_iint_cache *iint = NULL;
 	struct ima_template_desc *template_desc;
 	char *pathbuf = NULL;
 	char filename[NAME_MAX];
 	const char *pathname = NULL;
 	int rc = 0, action, must_appraise = 0;
 	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 	struct evm_ima_xattr_data *xattr_value = NULL;
 	int xattr_len = 0;
 	bool violation_check;
 	enum hash_algo hash_algo;

 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return 0;

 	/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
 	 * bitmask based on the appraise/audit/measurement policy.
 	 * Included is the appraise submask.
 	 */
 	action = ima_get_action(inode, cred, secid, mask, func, &pcr);
 	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
 			   (ima_policy_flag & IMA_MEASURE));
 	if (!action && !violation_check)
 		return 0;

 	must_appraise = action & IMA_APPRAISE;

 	/*  Is the appraise rule hook specific?  */
 	if (action & IMA_FILE_APPRAISE)
 		func = FILE_CHECK;

 	inode_lock(inode);

 	if (action) {
 		iint = integrity_inode_get(inode);
 		if (!iint)
 			rc = -ENOMEM;
 	}

 	if (!rc && violation_check)
 		ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
 					 &pathbuf, &pathname, filename);

 	inode_unlock(inode);

 	if (rc)
 		goto out;
 	if (!action)
 		goto out;

 	mutex_lock(&iint->mutex);

 	if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
 		/* reset appraisal flags if ima_inode_post_setattr was called */
 		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
 				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
 				 IMA_ACTION_FLAGS);

 	/*
 	 * Re-evaulate the file if either the xattr has changed or the
 	 * kernel has no way of detecting file change on the filesystem.
 	 * (Limited to privileged mounted filesystems.)
 	 */
 	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
 	    ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
 	     !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
 	     !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
 		iint->flags &= ~IMA_DONE_MASK;
 		iint->measured_pcrs = 0;
 	}

 	/* Determine if already appraised/measured based on bitmask
 	 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
 	 *  IMA_AUDIT, IMA_AUDITED)
 	 */
 	iint->flags |= action;
 	action &= IMA_DO_MASK;
 	action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);

 	/* If target pcr is already measured, unset IMA_MEASURE action */
 	if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
 		action ^= IMA_MEASURE;

 	/* HASH sets the digital signature and update flags, nothing else */
 	if ((action & IMA_HASH) &&
 	    !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
 		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 		if ((xattr_value && xattr_len > 2) &&
 		    (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
 			set_bit(IMA_DIGSIG, &iint->atomic_flags);
 		iint->flags |= IMA_HASHED;
 		action ^= IMA_HASH;
 		set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 	}

 	/* Nothing to do, just return existing appraised status */
 	if (!action) {
 		if (must_appraise)
 			rc = ima_get_cache_status(iint, func);
 		goto out_locked;
 	}

 	template_desc = ima_template_desc_current();
 	if ((action & IMA_APPRAISE_SUBMASK) ||
 		    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
 		/* read 'security.ima' */
 		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);

 	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);

 	rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
 	if (rc != 0 && rc != -EBADF && rc != -EINVAL)
 		goto out_locked;

 	if (!pathbuf)	/* ima_rdwr_violation possibly pre-fetched */
 		pathname = ima_d_path(&file->f_path, &pathbuf, filename);

 	if (action & IMA_MEASURE)
 		ima_store_measurement(iint, file, pathname,
 				      xattr_value, xattr_len, pcr);
 	if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
 		inode_lock(inode);
 		rc = ima_appraise_measurement(func, iint, file, pathname,
 					      xattr_value, xattr_len);
 		inode_unlock(inode);
 	}
 	if (action & IMA_AUDIT)
 		ima_audit_measurement(iint, pathname);

 	if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
 		rc = 0;
 out_locked:
 	if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
 	     !(iint->flags & IMA_NEW_FILE))
 		rc = -EACCES;
 	mutex_unlock(&iint->mutex);
 	kfree(xattr_value);
 out:
 	if (pathbuf)
 		__putname(pathbuf);
 	if (must_appraise) {
 		if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
 			return -EACCES;
 		if (file->f_mode & FMODE_WRITE)
 			set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 	}
 	return 0;
 }

 /**
  * 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.
  *
  * On success return 0.  On integrity appraisal error, assuming the file
  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
  */
 int ima_file_mmap(struct file *file, unsigned long prot)
 {
 	u32 secid;

 	if (file && (prot & PROT_EXEC)) {
 		security_task_getsecid(current, &secid);
 		return process_measurement(file, current_cred(), secid, NULL,
 					   0, MAY_EXEC, MMAP_CHECK);
 	}

 	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.
  *
  * On success return 0.  On integrity appraisal error, assuming the file
  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
  */
 int ima_bprm_check(struct linux_binprm *bprm)
 {
 	int ret;
 	u32 secid;

 	security_task_getsecid(current, &secid);
 	ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
 				  MAY_EXEC, BPRM_CHECK);
 	if (ret)
 		return ret;

 	security_cred_getsecid(bprm->cred, &secid);
 	return process_measurement(bprm->file, bprm->cred, secid, NULL, 0,
 				   MAY_EXEC, CREDS_CHECK);
 }

 /**
  * ima_path_check - based on policy, collect/store measurement.
  * @file: pointer to the file to be measured
  * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
  *
  * Measure files based on the ima_must_measure() policy decision.
  *
  * On success return 0.  On integrity appraisal error, assuming the file
  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
  */
 int ima_file_check(struct file *file, int mask)
 {
 	u32 secid;

 	security_task_getsecid(current, &secid);
 	return process_measurement(file, current_cred(), secid, NULL, 0,
 				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
 					   MAY_APPEND), FILE_CHECK);
 }
 EXPORT_SYMBOL_GPL(ima_file_check);

 /**
  * ima_post_path_mknod - mark as a new inode
  * @dentry: newly created dentry
  *
  * Mark files created via the mknodat syscall as new, so that the
  * file data can be written later.
  */
 void ima_post_path_mknod(struct dentry *dentry)
 {
 	struct integrity_iint_cache *iint;
 	struct inode *inode = dentry->d_inode;
 	int must_appraise;

 	must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
 	if (!must_appraise)
 		return;

 	iint = integrity_inode_get(inode);
 	if (iint)
 		iint->flags |= IMA_NEW_FILE;
 }

 /**
  * ima_read_file - pre-measure/appraise hook decision based on policy
  * @file: pointer to the file to be measured/appraised/audit
  * @read_id: caller identifier
  *
  * Permit reading a file based on policy. The policy rules are written
  * in terms of the policy identifier.  Appraising the integrity of
  * a file requires a file descriptor.
  *
  * For permission return 0, otherwise return -EACCES.
  */
 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 {
 	/*
 	 * READING_FIRMWARE_PREALLOC_BUFFER
 	 *
 	 * Do devices using pre-allocated memory run the risk of the
 	 * firmware being accessible to the device prior to the completion
 	 * of IMA's signature verification any more than when using two
 	 * buffers?
 	 */
 	return 0;
 }

 static const int read_idmap[READING_MAX_ID] = {
 	[READING_FIRMWARE] = FIRMWARE_CHECK,
 	[READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
 	[READING_MODULE] = MODULE_CHECK,
 	[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
 	[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
 	[READING_POLICY] = POLICY_CHECK
 };

 /**
  * ima_post_read_file - in memory collect/appraise/audit measurement
  * @file: pointer to the file to be measured/appraised/audit
  * @buf: pointer to in memory file contents
  * @size: size of in memory file contents
  * @read_id: caller identifier
  *
  * Measure/appraise/audit in memory file based on policy.  Policy rules
  * are written in terms of a policy identifier.
  *
  * On success return 0.  On integrity appraisal error, assuming the file
  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
  */
 int ima_post_read_file(struct file *file, void *buf, loff_t size,
 		       enum kernel_read_file_id read_id)
 {
 	enum ima_hooks func;
 	u32 secid;

 	if (!file && read_id == READING_FIRMWARE) {
 		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
 		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
 			pr_err("Prevent firmware loading_store.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 		return 0;
 	}

 	/* permit signed certs */
 	if (!file && read_id == READING_X509_CERTIFICATE)
 		return 0;

 	if (!file || !buf || size == 0) { /* should never happen */
 		if (ima_appraise & IMA_APPRAISE_ENFORCE)
 			return -EACCES;
 		return 0;
 	}

 	func = read_idmap[read_id] ?: FILE_CHECK;
 	security_task_getsecid(current, &secid);
 	return process_measurement(file, current_cred(), secid, buf, size,
 				   MAY_READ, func);
 }

 /**
  * ima_load_data - appraise decision based on policy
  * @id: kernel load data caller identifier
  *
  * Callers of this LSM hook can not measure, appraise, or audit the
  * data provided by userspace.  Enforce policy rules requring a file
  * signature (eg. kexec'ed kernel image).
  *
  * For permission return 0, otherwise return -EACCES.
  */
 int ima_load_data(enum kernel_load_data_id id)
 {
 	bool sig_enforce;

 	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
 		return 0;

 	switch (id) {
 	case LOADING_KEXEC_IMAGE:
 		if (ima_appraise & IMA_APPRAISE_KEXEC) {
 			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 		break;
 	case LOADING_FIRMWARE:
 		if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
 			pr_err("Prevent firmware sysfs fallback loading.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 		break;
 	case LOADING_MODULE:
 		sig_enforce = is_module_sig_enforced();

 		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
 			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 	default:
 		break;
 	}
 	return 0;
 }

 static int __init init_ima(void)
 {
 	int error;

 	ima_init_template_list();
 	hash_setup(CONFIG_IMA_DEFAULT_HASH);
 	error = ima_init();

 	if (error && strcmp(hash_algo_name[ima_hash_algo],
 			    CONFIG_IMA_DEFAULT_HASH) != 0) {
 		pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
 			hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
 		hash_setup_done = 0;
 		hash_setup(CONFIG_IMA_DEFAULT_HASH);
 		error = ima_init();
 	}

 	if (!error)
 		ima_update_policy_flag();

 	return error;
 }

 late_initcall(init_ima);	/* Start IMA after the TPM is available */
	/*
	* Integrity Measurement Architecture
	*
	* 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.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/init.h>
	#include <linux/file.h>
	#include <linux/binfmts.h>
	#include <linux/mount.h>
	#include <linux/mman.h>
	#include <linux/slab.h>
	#include <linux/xattr.h>
	#include <linux/ima.h>
	#include <linux/iversion.h>
	#include <linux/fs.h>

	#include "ima.h"

	#ifdef CONFIG_IMA_APPRAISE
	int ima_appraise = IMA_APPRAISE_ENFORCE;
	#else
	int ima_appraise;
	#endif

	int ima_hash_algo = HASH_ALGO_SHA1;
	static int hash_setup_done;

	static int __init hash_setup(char *str)
	{
	struct ima_template_desc *template_desc = ima_template_desc_current();
	int i;

	if (hash_setup_done)
	return 1;

	if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
	if (strncmp(str, "sha1", 4) == 0)
	ima_hash_algo = HASH_ALGO_SHA1;
	else if (strncmp(str, "md5", 3) == 0)
	ima_hash_algo = HASH_ALGO_MD5;
	else
	return 1;
	goto out;
	}

	i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
	if (i < 0)
	return 1;

	ima_hash_algo = i;
	out:
	hash_setup_done = 1;
	return 1;
	}
	__setup("ima_hash=", hash_setup);

	/*
	* ima_rdwr_violation_check
	*
	* 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.
	*
	*/
	static void ima_rdwr_violation_check(struct file *file,
	struct integrity_iint_cache *iint,
	int must_measure,
	char **pathbuf,
	const char **pathname,
	char *filename)
	{
	struct inode *inode = file_inode(file);
	fmode_t mode = file->f_mode;
	bool send_tomtou = false, send_writers = false;

	if (mode & FMODE_WRITE) {
	if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
	if (!iint)
	iint = integrity_iint_find(inode);
	/* IMA_MEASURE is set from reader side */
	if (iint && test_bit(IMA_MUST_MEASURE,
	&iint->atomic_flags))
	send_tomtou = true;
	}
	} else {
	if (must_measure)
	set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
	if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
	send_writers = true;
	}

	if (!send_tomtou && !send_writers)
	return;

	*pathname = ima_d_path(&file->f_path, pathbuf, filename);

	if (send_tomtou)
	ima_add_violation(file, *pathname, iint,
	"invalid_pcr", "ToMToU");
	if (send_writers)
	ima_add_violation(file, *pathname, iint,
	"invalid_pcr", "open_writers");
	}

	static void ima_check_last_writer(struct integrity_iint_cache *iint,
	struct inode inode, struct file file)
	{
	fmode_t mode = file->f_mode;
	bool update;

	if (!(mode & FMODE_WRITE))
	return;

	mutex_lock(&iint->mutex);
	if (atomic_read(&inode->i_writecount) == 1) {
	update = test_and_clear_bit(IMA_UPDATE_XATTR,
	&iint->atomic_flags);
	if (!IS_I_VERSION(inode) \|\|
	!inode_eq_iversion(inode, iint->version) \|\|
	(iint->flags & IMA_NEW_FILE)) {
	iint->flags &= ~(IMA_DONE_MASK \| IMA_NEW_FILE);
	iint->measured_pcrs = 0;
	if (update)
	ima_update_xattr(iint, file);
	}
	}
	mutex_unlock(&iint->mutex);
	}

	/**
	* ima_file_free - called on __fput()
	* @file: pointer to file structure being freed
	*
	* Flag files that changed, based on i_version
	*/
	void ima_file_free(struct file *file)
	{
	struct inode *inode = file_inode(file);
	struct integrity_iint_cache *iint;

	if (!ima_policy_flag \|\| !S_ISREG(inode->i_mode))
	return;

	iint = integrity_iint_find(inode);
	if (!iint)
	return;

	ima_check_last_writer(iint, inode, file);
	}

	static int process_measurement(struct file file, const struct cred cred,
	u32 secid, char *buf, loff_t size, int mask,
	enum ima_hooks func)
	{
	struct inode *inode = file_inode(file);
	struct integrity_iint_cache *iint = NULL;
	struct ima_template_desc *template_desc;
	char *pathbuf = NULL;
	char filename[NAME_MAX];
	const char *pathname = NULL;
	int rc = 0, action, must_appraise = 0;
	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
	struct evm_ima_xattr_data *xattr_value = NULL;
	int xattr_len = 0;
	bool violation_check;
	enum hash_algo hash_algo;

	if (!ima_policy_flag \|\| !S_ISREG(inode->i_mode))
	return 0;

	/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
	* bitmask based on the appraise/audit/measurement policy.
	* Included is the appraise submask.
	*/
	action = ima_get_action(inode, cred, secid, mask, func, &pcr);
	violation_check = ((func == FILE_CHECK \|\| func == MMAP_CHECK) &&
	(ima_policy_flag & IMA_MEASURE));
	if (!action && !violation_check)
	return 0;

	must_appraise = action & IMA_APPRAISE;

	/* Is the appraise rule hook specific? */
	if (action & IMA_FILE_APPRAISE)
	func = FILE_CHECK;

	inode_lock(inode);

	if (action) {
	iint = integrity_inode_get(inode);
	if (!iint)
	rc = -ENOMEM;
	}

	if (!rc && violation_check)
	ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
	&pathbuf, &pathname, filename);

	inode_unlock(inode);

	if (rc)
	goto out;
	if (!action)
	goto out;

	mutex_lock(&iint->mutex);

	if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
	/* reset appraisal flags if ima_inode_post_setattr was called */
	iint->flags &= ~(IMA_APPRAISE \| IMA_APPRAISED \|
	IMA_APPRAISE_SUBMASK \| IMA_APPRAISED_SUBMASK \|
	IMA_ACTION_FLAGS);

	/*
	* Re-evaulate the file if either the xattr has changed or the
	* kernel has no way of detecting file change on the filesystem.
	* (Limited to privileged mounted filesystems.)
	*/
	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) \|\|
	((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
	!(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
	!(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
	iint->flags &= ~IMA_DONE_MASK;
	iint->measured_pcrs = 0;
	}

	/* Determine if already appraised/measured based on bitmask
	* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
	* IMA_AUDIT, IMA_AUDITED)
	*/
	iint->flags \|= action;
	action &= IMA_DO_MASK;
	action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);

	/* If target pcr is already measured, unset IMA_MEASURE action */
	if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
	action ^= IMA_MEASURE;

	/* HASH sets the digital signature and update flags, nothing else */
	if ((action & IMA_HASH) &&
	!(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
	xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
	if ((xattr_value && xattr_len > 2) &&
	(xattr_value->type == EVM_IMA_XATTR_DIGSIG))
	set_bit(IMA_DIGSIG, &iint->atomic_flags);
	iint->flags \|= IMA_HASHED;
	action ^= IMA_HASH;
	set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
	}

	/* Nothing to do, just return existing appraised status */
	if (!action) {
	if (must_appraise)
	rc = ima_get_cache_status(iint, func);
	goto out_locked;
	}

	template_desc = ima_template_desc_current();
	if ((action & IMA_APPRAISE_SUBMASK) \|\|
	strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
	/* read 'security.ima' */
	xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);

	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);

	rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
	if (rc != 0 && rc != -EBADF && rc != -EINVAL)
	goto out_locked;

	if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
	pathname = ima_d_path(&file->f_path, &pathbuf, filename);

	if (action & IMA_MEASURE)
	ima_store_measurement(iint, file, pathname,
	xattr_value, xattr_len, pcr);
	if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
	inode_lock(inode);
	rc = ima_appraise_measurement(func, iint, file, pathname,
	xattr_value, xattr_len);
	inode_unlock(inode);
	}
	if (action & IMA_AUDIT)
	ima_audit_measurement(iint, pathname);

	if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
	rc = 0;
	out_locked:
	if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
	!(iint->flags & IMA_NEW_FILE))
	rc = -EACCES;
	mutex_unlock(&iint->mutex);
	kfree(xattr_value);
	out:
	if (pathbuf)
	__putname(pathbuf);
	if (must_appraise) {
	if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
	return -EACCES;
	if (file->f_mode & FMODE_WRITE)
	set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
	}
	return 0;
	}

	/**
	* 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.
	*
	* On success return 0. On integrity appraisal error, assuming the file
	* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
	*/
	int ima_file_mmap(struct file *file, unsigned long prot)
	{
	u32 secid;

	if (file && (prot & PROT_EXEC)) {
	security_task_getsecid(current, &secid);
	return process_measurement(file, current_cred(), secid, NULL,
	0, MAY_EXEC, MMAP_CHECK);
	}

	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.
	*
	* On success return 0. On integrity appraisal error, assuming the file
	* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
	*/
	int ima_bprm_check(struct linux_binprm *bprm)
	{
	int ret;
	u32 secid;

	security_task_getsecid(current, &secid);
	ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
	MAY_EXEC, BPRM_CHECK);
	if (ret)
	return ret;

	security_cred_getsecid(bprm->cred, &secid);
	return process_measurement(bprm->file, bprm->cred, secid, NULL, 0,
	MAY_EXEC, CREDS_CHECK);
	}

	/**
	* ima_path_check - based on policy, collect/store measurement.
	* @file: pointer to the file to be measured
	* @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
	*
	* Measure files based on the ima_must_measure() policy decision.
	*
	* On success return 0. On integrity appraisal error, assuming the file
	* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
	*/
	int ima_file_check(struct file *file, int mask)
	{
	u32 secid;

	security_task_getsecid(current, &secid);
	return process_measurement(file, current_cred(), secid, NULL, 0,
	mask & (MAY_READ \| MAY_WRITE \| MAY_EXEC \|
	MAY_APPEND), FILE_CHECK);
	}
	EXPORT_SYMBOL_GPL(ima_file_check);

	/**
	* ima_post_path_mknod - mark as a new inode
	* @dentry: newly created dentry
	*
	* Mark files created via the mknodat syscall as new, so that the
	* file data can be written later.
	*/
	void ima_post_path_mknod(struct dentry *dentry)
	{
	struct integrity_iint_cache *iint;
	struct inode *inode = dentry->d_inode;
	int must_appraise;

	must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
	if (!must_appraise)
	return;

	iint = integrity_inode_get(inode);
	if (iint)
	iint->flags \|= IMA_NEW_FILE;
	}

	/**
	* ima_read_file - pre-measure/appraise hook decision based on policy
	* @file: pointer to the file to be measured/appraised/audit
	* @read_id: caller identifier
	*
	* Permit reading a file based on policy. The policy rules are written
	* in terms of the policy identifier. Appraising the integrity of
	* a file requires a file descriptor.
	*
	* For permission return 0, otherwise return -EACCES.
	*/
	int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
	{
	/*
	* READING_FIRMWARE_PREALLOC_BUFFER
	*
	* Do devices using pre-allocated memory run the risk of the
	* firmware being accessible to the device prior to the completion
	* of IMA's signature verification any more than when using two
	* buffers?
	*/
	return 0;
	}

	static const int read_idmap[READING_MAX_ID] = {
	[READING_FIRMWARE] = FIRMWARE_CHECK,
	[READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
	[READING_MODULE] = MODULE_CHECK,
	[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
	[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
	[READING_POLICY] = POLICY_CHECK
	};

	/**
	* ima_post_read_file - in memory collect/appraise/audit measurement
	* @file: pointer to the file to be measured/appraised/audit
	* @buf: pointer to in memory file contents
	* @size: size of in memory file contents
	* @read_id: caller identifier
	*
	* Measure/appraise/audit in memory file based on policy. Policy rules
	* are written in terms of a policy identifier.
	*
	* On success return 0. On integrity appraisal error, assuming the file
	* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
	*/
	int ima_post_read_file(struct file file, void buf, loff_t size,
	enum kernel_read_file_id read_id)
	{
	enum ima_hooks func;
	u32 secid;

	if (!file && read_id == READING_FIRMWARE) {
	if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
	(ima_appraise & IMA_APPRAISE_ENFORCE)) {
	pr_err("Prevent firmware loading_store.\n");
	return -EACCES; /* INTEGRITY_UNKNOWN */
	}
	return 0;
	}

	/* permit signed certs */
	if (!file && read_id == READING_X509_CERTIFICATE)
	return 0;

	if (!file \|\| !buf \|\| size == 0) { /* should never happen */
	if (ima_appraise & IMA_APPRAISE_ENFORCE)
	return -EACCES;
	return 0;
	}

	func = read_idmap[read_id] ?: FILE_CHECK;
	security_task_getsecid(current, &secid);
	return process_measurement(file, current_cred(), secid, buf, size,
	MAY_READ, func);
	}

	/**
	* ima_load_data - appraise decision based on policy
	* @id: kernel load data caller identifier
	*
	* Callers of this LSM hook can not measure, appraise, or audit the
	* data provided by userspace. Enforce policy rules requring a file
	* signature (eg. kexec'ed kernel image).
	*
	* For permission return 0, otherwise return -EACCES.
	*/
	int ima_load_data(enum kernel_load_data_id id)
	{
	bool sig_enforce;

	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
	return 0;

	switch (id) {
	case LOADING_KEXEC_IMAGE:
	if (ima_appraise & IMA_APPRAISE_KEXEC) {
	pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
	return -EACCES; /* INTEGRITY_UNKNOWN */
	}
	break;
	case LOADING_FIRMWARE:
	if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
	pr_err("Prevent firmware sysfs fallback loading.\n");
	return -EACCES; /* INTEGRITY_UNKNOWN */
	}
	break;
	case LOADING_MODULE:
	sig_enforce = is_module_sig_enforced();

	if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
	pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
	return -EACCES; /* INTEGRITY_UNKNOWN */
	}
	default:
	break;
	}
	return 0;
	}

	static int __init init_ima(void)
	{
	int error;

	ima_init_template_list();
	hash_setup(CONFIG_IMA_DEFAULT_HASH);
	error = ima_init();

	if (error && strcmp(hash_algo_name[ima_hash_algo],
	CONFIG_IMA_DEFAULT_HASH) != 0) {
	pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
	hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
	hash_setup_done = 0;
	hash_setup(CONFIG_IMA_DEFAULT_HASH);
	error = ima_init();
	}

	if (!error)
	ima_update_policy_flag();

	return error;
	}

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