security/integrity/ima/ima_crypto.c - third_party/linux - Git at Google

 /*
  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
  *
  * Authors:
  * Mimi Zohar <zohar@us.ibm.com>
  * Kylene Hall <kjhall@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_crypto.c
  *	Calculates md5/sha1 file hash, template hash, boot-aggreate hash
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include <linux/ratelimit.h>
 #include <linux/file.h>
 #include <linux/crypto.h>
 #include <linux/scatterlist.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <crypto/hash.h>

 #include "ima.h"

 /* minimum file size for ahash use */
 static unsigned long ima_ahash_minsize;
 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");

 /* default is 0 - 1 page. */
 static int ima_maxorder;
 static unsigned int ima_bufsize = PAGE_SIZE;

 static int param_set_bufsize(const char *val, const struct kernel_param *kp)
 {
 	unsigned long long size;
 	int order;

 	size = memparse(val, NULL);
 	order = get_order(size);
 	if (order >= MAX_ORDER)
 		return -EINVAL;
 	ima_maxorder = order;
 	ima_bufsize = PAGE_SIZE << order;
 	return 0;
 }

 static const struct kernel_param_ops param_ops_bufsize = {
 	.set = param_set_bufsize,
 	.get = param_get_uint,
 };
 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int)

 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");

 static struct crypto_shash *ima_shash_tfm;
 static struct crypto_ahash *ima_ahash_tfm;

 int __init ima_init_crypto(void)
 {
 	long rc;

 	ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
 	if (IS_ERR(ima_shash_tfm)) {
 		rc = PTR_ERR(ima_shash_tfm);
 		pr_err("Can not allocate %s (reason: %ld)\n",
 		       hash_algo_name[ima_hash_algo], rc);
 		return rc;
 	}
 	pr_info("Allocated hash algorithm: %s\n",
 		hash_algo_name[ima_hash_algo]);
 	return 0;
 }

 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
 {
 	struct crypto_shash *tfm = ima_shash_tfm;
 	int rc;

 	if (algo < 0 || algo >= HASH_ALGO__LAST)
 		algo = ima_hash_algo;

 	if (algo != ima_hash_algo) {
 		tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
 		if (IS_ERR(tfm)) {
 			rc = PTR_ERR(tfm);
 			pr_err("Can not allocate %s (reason: %d)\n",
 			       hash_algo_name[algo], rc);
 		}
 	}
 	return tfm;
 }

 static void ima_free_tfm(struct crypto_shash *tfm)
 {
 	if (tfm != ima_shash_tfm)
 		crypto_free_shash(tfm);
 }

 /**
  * ima_alloc_pages() - Allocate contiguous pages.
  * @max_size:       Maximum amount of memory to allocate.
  * @allocated_size: Returned size of actual allocation.
  * @last_warn:      Should the min_size allocation warn or not.
  *
  * Tries to do opportunistic allocation for memory first trying to allocate
  * max_size amount of memory and then splitting that until zero order is
  * reached. Allocation is tried without generating allocation warnings unless
  * last_warn is set. Last_warn set affects only last allocation of zero order.
  *
  * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
  *
  * Return pointer to allocated memory, or NULL on failure.
  */
 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
 			     int last_warn)
 {
 	void *ptr;
 	int order = ima_maxorder;
 	gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;

 	if (order)
 		order = min(get_order(max_size), order);

 	for (; order; order--) {
 		ptr = (void *)__get_free_pages(gfp_mask, order);
 		if (ptr) {
 			*allocated_size = PAGE_SIZE << order;
 			return ptr;
 		}
 	}

 	/* order is zero - one page */

 	gfp_mask = GFP_KERNEL;

 	if (!last_warn)
 		gfp_mask |= __GFP_NOWARN;

 	ptr = (void *)__get_free_pages(gfp_mask, 0);
 	if (ptr) {
 		*allocated_size = PAGE_SIZE;
 		return ptr;
 	}

 	*allocated_size = 0;
 	return NULL;
 }

 /**
  * ima_free_pages() - Free pages allocated by ima_alloc_pages().
  * @ptr:  Pointer to allocated pages.
  * @size: Size of allocated buffer.
  */
 static void ima_free_pages(void *ptr, size_t size)
 {
 	if (!ptr)
 		return;
 	free_pages((unsigned long)ptr, get_order(size));
 }

 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
 {
 	struct crypto_ahash *tfm = ima_ahash_tfm;
 	int rc;

 	if (algo < 0 || algo >= HASH_ALGO__LAST)
 		algo = ima_hash_algo;

 	if (algo != ima_hash_algo || !tfm) {
 		tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
 		if (!IS_ERR(tfm)) {
 			if (algo == ima_hash_algo)
 				ima_ahash_tfm = tfm;
 		} else {
 			rc = PTR_ERR(tfm);
 			pr_err("Can not allocate %s (reason: %d)\n",
 			       hash_algo_name[algo], rc);
 		}
 	}
 	return tfm;
 }

 static void ima_free_atfm(struct crypto_ahash *tfm)
 {
 	if (tfm != ima_ahash_tfm)
 		crypto_free_ahash(tfm);
 }

 static inline int ahash_wait(int err, struct crypto_wait *wait)
 {

 	err = crypto_wait_req(err, wait);

 	if (err)
 		pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);

 	return err;
 }

 static int ima_calc_file_hash_atfm(struct file *file,
 				   struct ima_digest_data *hash,
 				   struct crypto_ahash *tfm)
 {
 	loff_t i_size, offset;
 	char *rbuf[2] = { NULL, };
 	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
 	struct ahash_request *req;
 	struct scatterlist sg[1];
 	struct crypto_wait wait;
 	size_t rbuf_size[2];

 	hash->length = crypto_ahash_digestsize(tfm);

 	req = ahash_request_alloc(tfm, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;

 	crypto_init_wait(&wait);
 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 				   CRYPTO_TFM_REQ_MAY_SLEEP,
 				   crypto_req_done, &wait);

 	rc = ahash_wait(crypto_ahash_init(req), &wait);
 	if (rc)
 		goto out1;

 	i_size = i_size_read(file_inode(file));

 	if (i_size == 0)
 		goto out2;

 	/*
 	 * Try to allocate maximum size of memory.
 	 * Fail if even a single page cannot be allocated.
 	 */
 	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
 	if (!rbuf[0]) {
 		rc = -ENOMEM;
 		goto out1;
 	}

 	/* Only allocate one buffer if that is enough. */
 	if (i_size > rbuf_size[0]) {
 		/*
 		 * Try to allocate secondary buffer. If that fails fallback to
 		 * using single buffering. Use previous memory allocation size
 		 * as baseline for possible allocation size.
 		 */
 		rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
 					  &rbuf_size[1], 0);
 	}

 	if (!(file->f_mode & FMODE_READ)) {
 		file->f_mode |= FMODE_READ;
 		read = 1;
 	}

 	for (offset = 0; offset < i_size; offset += rbuf_len) {
 		if (!rbuf[1] && offset) {
 			/* Not using two buffers, and it is not the first
 			 * read/request, wait for the completion of the
 			 * previous ahash_update() request.
 			 */
 			rc = ahash_wait(ahash_rc, &wait);
 			if (rc)
 				goto out3;
 		}
 		/* read buffer */
 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
 		rc = integrity_kernel_read(file, offset, rbuf[active],
 					   rbuf_len);
 		if (rc != rbuf_len)
 			goto out3;

 		if (rbuf[1] && offset) {
 			/* Using two buffers, and it is not the first
 			 * read/request, wait for the completion of the
 			 * previous ahash_update() request.
 			 */
 			rc = ahash_wait(ahash_rc, &wait);
 			if (rc)
 				goto out3;
 		}

 		sg_init_one(&sg[0], rbuf[active], rbuf_len);
 		ahash_request_set_crypt(req, sg, NULL, rbuf_len);

 		ahash_rc = crypto_ahash_update(req);

 		if (rbuf[1])
 			active = !active; /* swap buffers, if we use two */
 	}
 	/* wait for the last update request to complete */
 	rc = ahash_wait(ahash_rc, &wait);
 out3:
 	if (read)
 		file->f_mode &= ~FMODE_READ;
 	ima_free_pages(rbuf[0], rbuf_size[0]);
 	ima_free_pages(rbuf[1], rbuf_size[1]);
 out2:
 	if (!rc) {
 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
 		rc = ahash_wait(crypto_ahash_final(req), &wait);
 	}
 out1:
 	ahash_request_free(req);
 	return rc;
 }

 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
 {
 	struct crypto_ahash *tfm;
 	int rc;

 	tfm = ima_alloc_atfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	rc = ima_calc_file_hash_atfm(file, hash, tfm);

 	ima_free_atfm(tfm);

 	return rc;
 }

 static int ima_calc_file_hash_tfm(struct file *file,
 				  struct ima_digest_data *hash,
 				  struct crypto_shash *tfm)
 {
 	loff_t i_size, offset = 0;
 	char *rbuf;
 	int rc, read = 0;
 	SHASH_DESC_ON_STACK(shash, tfm);

 	shash->tfm = tfm;
 	shash->flags = 0;

 	hash->length = crypto_shash_digestsize(tfm);

 	rc = crypto_shash_init(shash);
 	if (rc != 0)
 		return rc;

 	i_size = i_size_read(file_inode(file));

 	if (i_size == 0)
 		goto out;

 	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!rbuf)
 		return -ENOMEM;

 	if (!(file->f_mode & FMODE_READ)) {
 		file->f_mode |= FMODE_READ;
 		read = 1;
 	}

 	while (offset < i_size) {
 		int rbuf_len;

 		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
 		if (rbuf_len < 0) {
 			rc = rbuf_len;
 			break;
 		}
 		if (rbuf_len == 0)
 			break;
 		offset += rbuf_len;

 		rc = crypto_shash_update(shash, rbuf, rbuf_len);
 		if (rc)
 			break;
 	}
 	if (read)
 		file->f_mode &= ~FMODE_READ;
 	kfree(rbuf);
 out:
 	if (!rc)
 		rc = crypto_shash_final(shash, hash->digest);
 	return rc;
 }

 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
 	int rc;

 	tfm = ima_alloc_tfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	rc = ima_calc_file_hash_tfm(file, hash, tfm);

 	ima_free_tfm(tfm);

 	return rc;
 }

 /*
  * ima_calc_file_hash - calculate file hash
  *
  * Asynchronous hash (ahash) allows using HW acceleration for calculating
  * a hash. ahash performance varies for different data sizes on different
  * crypto accelerators. shash performance might be better for smaller files.
  * The 'ima.ahash_minsize' module parameter allows specifying the best
  * minimum file size for using ahash on the system.
  *
  * If the ima.ahash_minsize parameter is not specified, this function uses
  * shash for the hash calculation.  If ahash fails, it falls back to using
  * shash.
  */
 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 {
 	loff_t i_size;
 	int rc;

 	/*
 	 * For consistency, fail file's opened with the O_DIRECT flag on
 	 * filesystems mounted with/without DAX option.
 	 */
 	if (file->f_flags & O_DIRECT) {
 		hash->length = hash_digest_size[ima_hash_algo];
 		hash->algo = ima_hash_algo;
 		return -EINVAL;
 	}

 	i_size = i_size_read(file_inode(file));

 	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
 		rc = ima_calc_file_ahash(file, hash);
 		if (!rc)
 			return 0;
 	}

 	return ima_calc_file_shash(file, hash);
 }

 /*
  * Calculate the hash of template data
  */
 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
 					 struct ima_template_desc *td,
 					 int num_fields,
 					 struct ima_digest_data *hash,
 					 struct crypto_shash *tfm)
 {
 	SHASH_DESC_ON_STACK(shash, tfm);
 	int rc, i;

 	shash->tfm = tfm;
 	shash->flags = 0;

 	hash->length = crypto_shash_digestsize(tfm);

 	rc = crypto_shash_init(shash);
 	if (rc != 0)
 		return rc;

 	for (i = 0; i < num_fields; i++) {
 		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
 		u8 *data_to_hash = field_data[i].data;
 		u32 datalen = field_data[i].len;
 		u32 datalen_to_hash =
 		    !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);

 		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 			rc = crypto_shash_update(shash,
 						(const u8 *) &datalen_to_hash,
 						sizeof(datalen_to_hash));
 			if (rc)
 				break;
 		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
 			memcpy(buffer, data_to_hash, datalen);
 			data_to_hash = buffer;
 			datalen = IMA_EVENT_NAME_LEN_MAX + 1;
 		}
 		rc = crypto_shash_update(shash, data_to_hash, datalen);
 		if (rc)
 			break;
 	}

 	if (!rc)
 		rc = crypto_shash_final(shash, hash->digest);

 	return rc;
 }

 int ima_calc_field_array_hash(struct ima_field_data *field_data,
 			      struct ima_template_desc *desc, int num_fields,
 			      struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
 	int rc;

 	tfm = ima_alloc_tfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
 					   hash, tfm);

 	ima_free_tfm(tfm);

 	return rc;
 }

 static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
 				  struct ima_digest_data *hash,
 				  struct crypto_ahash *tfm)
 {
 	struct ahash_request *req;
 	struct scatterlist sg;
 	struct crypto_wait wait;
 	int rc, ahash_rc = 0;

 	hash->length = crypto_ahash_digestsize(tfm);

 	req = ahash_request_alloc(tfm, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;

 	crypto_init_wait(&wait);
 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 				   CRYPTO_TFM_REQ_MAY_SLEEP,
 				   crypto_req_done, &wait);

 	rc = ahash_wait(crypto_ahash_init(req), &wait);
 	if (rc)
 		goto out;

 	sg_init_one(&sg, buf, len);
 	ahash_request_set_crypt(req, &sg, NULL, len);

 	ahash_rc = crypto_ahash_update(req);

 	/* wait for the update request to complete */
 	rc = ahash_wait(ahash_rc, &wait);
 	if (!rc) {
 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
 		rc = ahash_wait(crypto_ahash_final(req), &wait);
 	}
 out:
 	ahash_request_free(req);
 	return rc;
 }

 static int calc_buffer_ahash(const void *buf, loff_t len,
 			     struct ima_digest_data *hash)
 {
 	struct crypto_ahash *tfm;
 	int rc;

 	tfm = ima_alloc_atfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);

 	ima_free_atfm(tfm);

 	return rc;
 }

 static int calc_buffer_shash_tfm(const void *buf, loff_t size,
 				struct ima_digest_data *hash,
 				struct crypto_shash *tfm)
 {
 	SHASH_DESC_ON_STACK(shash, tfm);
 	unsigned int len;
 	int rc;

 	shash->tfm = tfm;
 	shash->flags = 0;

 	hash->length = crypto_shash_digestsize(tfm);

 	rc = crypto_shash_init(shash);
 	if (rc != 0)
 		return rc;

 	while (size) {
 		len = size < PAGE_SIZE ? size : PAGE_SIZE;
 		rc = crypto_shash_update(shash, buf, len);
 		if (rc)
 			break;
 		buf += len;
 		size -= len;
 	}

 	if (!rc)
 		rc = crypto_shash_final(shash, hash->digest);
 	return rc;
 }

 static int calc_buffer_shash(const void *buf, loff_t len,
 			     struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
 	int rc;

 	tfm = ima_alloc_tfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	rc = calc_buffer_shash_tfm(buf, len, hash, tfm);

 	ima_free_tfm(tfm);
 	return rc;
 }

 int ima_calc_buffer_hash(const void *buf, loff_t len,
 			 struct ima_digest_data *hash)
 {
 	int rc;

 	if (ima_ahash_minsize && len >= ima_ahash_minsize) {
 		rc = calc_buffer_ahash(buf, len, hash);
 		if (!rc)
 			return 0;
 	}

 	return calc_buffer_shash(buf, len, hash);
 }

 static void __init ima_pcrread(int idx, u8 *pcr)
 {
 	if (!ima_used_chip)
 		return;

 	if (tpm_pcr_read(NULL, idx, pcr) != 0)
 		pr_err("Error Communicating to TPM chip\n");
 }

 /*
  * Calculate the boot aggregate hash
  */
 static int __init ima_calc_boot_aggregate_tfm(char *digest,
 					      struct crypto_shash *tfm)
 {
 	u8 pcr_i[TPM_DIGEST_SIZE];
 	int rc, i;
 	SHASH_DESC_ON_STACK(shash, tfm);

 	shash->tfm = tfm;
 	shash->flags = 0;

 	rc = crypto_shash_init(shash);
 	if (rc != 0)
 		return rc;

 	/* cumulative sha1 over tpm registers 0-7 */
 	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
 		ima_pcrread(i, pcr_i);
 		/* now accumulate with current aggregate */
 		rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
 	}
 	if (!rc)
 		crypto_shash_final(shash, digest);
 	return rc;
 }

 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
 	int rc;

 	tfm = ima_alloc_tfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);

 	hash->length = crypto_shash_digestsize(tfm);
 	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);

 	ima_free_tfm(tfm);

 	return rc;
 }
	/*
	* Copyright (C) 2005,2006,2007,2008 IBM Corporation
	*
	* Authors:
	* Mimi Zohar <zohar@us.ibm.com>
	* Kylene Hall <kjhall@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_crypto.c
	* Calculates md5/sha1 file hash, template hash, boot-aggreate hash
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/moduleparam.h>
	#include <linux/ratelimit.h>
	#include <linux/file.h>
	#include <linux/crypto.h>
	#include <linux/scatterlist.h>
	#include <linux/err.h>
	#include <linux/slab.h>
	#include <crypto/hash.h>

	#include "ima.h"

	/* minimum file size for ahash use */
	static unsigned long ima_ahash_minsize;
	module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
	MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");

	/* default is 0 - 1 page. */
	static int ima_maxorder;
	static unsigned int ima_bufsize = PAGE_SIZE;

	static int param_set_bufsize(const char val, const struct kernel_param kp)
	{
	unsigned long long size;
	int order;

	size = memparse(val, NULL);
	order = get_order(size);
	if (order >= MAX_ORDER)
	return -EINVAL;
	ima_maxorder = order;
	ima_bufsize = PAGE_SIZE << order;
	return 0;
	}

	static const struct kernel_param_ops param_ops_bufsize = {
	.set = param_set_bufsize,
	.get = param_get_uint,
	};
	#define param_check_bufsize(name, p) __param_check(name, p, unsigned int)

	module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
	MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");

	static struct crypto_shash *ima_shash_tfm;
	static struct crypto_ahash *ima_ahash_tfm;

	int __init ima_init_crypto(void)
	{
	long rc;

	ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
	if (IS_ERR(ima_shash_tfm)) {
	rc = PTR_ERR(ima_shash_tfm);
	pr_err("Can not allocate %s (reason: %ld)\n",
	hash_algo_name[ima_hash_algo], rc);
	return rc;
	}
	pr_info("Allocated hash algorithm: %s\n",
	hash_algo_name[ima_hash_algo]);
	return 0;
	}

	static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
	{
	struct crypto_shash *tfm = ima_shash_tfm;
	int rc;

	if (algo < 0 \|\| algo >= HASH_ALGO__LAST)
	algo = ima_hash_algo;

	if (algo != ima_hash_algo) {
	tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
	if (IS_ERR(tfm)) {
	rc = PTR_ERR(tfm);
	pr_err("Can not allocate %s (reason: %d)\n",
	hash_algo_name[algo], rc);
	}
	}
	return tfm;
	}

	static void ima_free_tfm(struct crypto_shash *tfm)
	{
	if (tfm != ima_shash_tfm)
	crypto_free_shash(tfm);
	}

	/**
	* ima_alloc_pages() - Allocate contiguous pages.
	* @max_size: Maximum amount of memory to allocate.
	* @allocated_size: Returned size of actual allocation.
	* @last_warn: Should the min_size allocation warn or not.
	*
	* Tries to do opportunistic allocation for memory first trying to allocate
	* max_size amount of memory and then splitting that until zero order is
	* reached. Allocation is tried without generating allocation warnings unless
	* last_warn is set. Last_warn set affects only last allocation of zero order.
	*
	* By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
	*
	* Return pointer to allocated memory, or NULL on failure.
	*/
	static void ima_alloc_pages(loff_t max_size, size_t allocated_size,
	int last_warn)
	{
	void *ptr;
	int order = ima_maxorder;
	gfp_t gfp_mask = __GFP_RECLAIM \| __GFP_NOWARN \| __GFP_NORETRY;

	if (order)
	order = min(get_order(max_size), order);

	for (; order; order--) {
	ptr = (void *)__get_free_pages(gfp_mask, order);
	if (ptr) {
	*allocated_size = PAGE_SIZE << order;
	return ptr;
	}
	}

	/* order is zero - one page */

	gfp_mask = GFP_KERNEL;

	if (!last_warn)
	gfp_mask \|= __GFP_NOWARN;

	ptr = (void *)__get_free_pages(gfp_mask, 0);
	if (ptr) {
	*allocated_size = PAGE_SIZE;
	return ptr;
	}

	*allocated_size = 0;
	return NULL;
	}

	/**
	* ima_free_pages() - Free pages allocated by ima_alloc_pages().
	* @ptr: Pointer to allocated pages.
	* @size: Size of allocated buffer.
	*/
	static void ima_free_pages(void *ptr, size_t size)
	{
	if (!ptr)
	return;
	free_pages((unsigned long)ptr, get_order(size));
	}

	static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
	{
	struct crypto_ahash *tfm = ima_ahash_tfm;
	int rc;

	if (algo < 0 \|\| algo >= HASH_ALGO__LAST)
	algo = ima_hash_algo;

	if (algo != ima_hash_algo \|\| !tfm) {
	tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
	if (!IS_ERR(tfm)) {
	if (algo == ima_hash_algo)
	ima_ahash_tfm = tfm;
	} else {
	rc = PTR_ERR(tfm);
	pr_err("Can not allocate %s (reason: %d)\n",
	hash_algo_name[algo], rc);
	}
	}
	return tfm;
	}

	static void ima_free_atfm(struct crypto_ahash *tfm)
	{
	if (tfm != ima_ahash_tfm)
	crypto_free_ahash(tfm);
	}

	static inline int ahash_wait(int err, struct crypto_wait *wait)
	{

	err = crypto_wait_req(err, wait);

	if (err)
	pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);

	return err;
	}

	static int ima_calc_file_hash_atfm(struct file *file,
	struct ima_digest_data *hash,
	struct crypto_ahash *tfm)
	{
	loff_t i_size, offset;
	char *rbuf[2] = { NULL, };
	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
	struct ahash_request *req;
	struct scatterlist sg[1];
	struct crypto_wait wait;
	size_t rbuf_size[2];

	hash->length = crypto_ahash_digestsize(tfm);

	req = ahash_request_alloc(tfm, GFP_KERNEL);
	if (!req)
	return -ENOMEM;

	crypto_init_wait(&wait);
	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG \|
	CRYPTO_TFM_REQ_MAY_SLEEP,
	crypto_req_done, &wait);

	rc = ahash_wait(crypto_ahash_init(req), &wait);
	if (rc)
	goto out1;

	i_size = i_size_read(file_inode(file));

	if (i_size == 0)
	goto out2;

	/*
	* Try to allocate maximum size of memory.
	* Fail if even a single page cannot be allocated.
	*/
	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
	if (!rbuf[0]) {
	rc = -ENOMEM;
	goto out1;
	}

	/* Only allocate one buffer if that is enough. */
	if (i_size > rbuf_size[0]) {
	/*
	* Try to allocate secondary buffer. If that fails fallback to
	* using single buffering. Use previous memory allocation size
	* as baseline for possible allocation size.
	*/
	rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
	&rbuf_size[1], 0);
	}

	if (!(file->f_mode & FMODE_READ)) {
	file->f_mode \|= FMODE_READ;
	read = 1;
	}

	for (offset = 0; offset < i_size; offset += rbuf_len) {
	if (!rbuf[1] && offset) {
	/* Not using two buffers, and it is not the first
	* read/request, wait for the completion of the
	* previous ahash_update() request.
	*/
	rc = ahash_wait(ahash_rc, &wait);
	if (rc)
	goto out3;
	}
	/* read buffer */
	rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
	rc = integrity_kernel_read(file, offset, rbuf[active],
	rbuf_len);
	if (rc != rbuf_len)
	goto out3;

	if (rbuf[1] && offset) {
	/* Using two buffers, and it is not the first
	* read/request, wait for the completion of the
	* previous ahash_update() request.
	*/
	rc = ahash_wait(ahash_rc, &wait);
	if (rc)
	goto out3;
	}

	sg_init_one(&sg[0], rbuf[active], rbuf_len);
	ahash_request_set_crypt(req, sg, NULL, rbuf_len);

	ahash_rc = crypto_ahash_update(req);

	if (rbuf[1])
	active = !active; /* swap buffers, if we use two */
	}
	/* wait for the last update request to complete */
	rc = ahash_wait(ahash_rc, &wait);
	out3:
	if (read)
	file->f_mode &= ~FMODE_READ;
	ima_free_pages(rbuf[0], rbuf_size[0]);
	ima_free_pages(rbuf[1], rbuf_size[1]);
	out2:
	if (!rc) {
	ahash_request_set_crypt(req, NULL, hash->digest, 0);
	rc = ahash_wait(crypto_ahash_final(req), &wait);
	}
	out1:
	ahash_request_free(req);
	return rc;
	}

	static int ima_calc_file_ahash(struct file file, struct ima_digest_data hash)
	{
	struct crypto_ahash *tfm;
	int rc;

	tfm = ima_alloc_atfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	rc = ima_calc_file_hash_atfm(file, hash, tfm);

	ima_free_atfm(tfm);

	return rc;
	}

	static int ima_calc_file_hash_tfm(struct file *file,
	struct ima_digest_data *hash,
	struct crypto_shash *tfm)
	{
	loff_t i_size, offset = 0;
	char *rbuf;
	int rc, read = 0;
	SHASH_DESC_ON_STACK(shash, tfm);

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
	return rc;

	i_size = i_size_read(file_inode(file));

	if (i_size == 0)
	goto out;

	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
	if (!rbuf)
	return -ENOMEM;

	if (!(file->f_mode & FMODE_READ)) {
	file->f_mode \|= FMODE_READ;
	read = 1;
	}

	while (offset < i_size) {
	int rbuf_len;

	rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
	if (rbuf_len < 0) {
	rc = rbuf_len;
	break;
	}
	if (rbuf_len == 0)
	break;
	offset += rbuf_len;

	rc = crypto_shash_update(shash, rbuf, rbuf_len);
	if (rc)
	break;
	}
	if (read)
	file->f_mode &= ~FMODE_READ;
	kfree(rbuf);
	out:
	if (!rc)
	rc = crypto_shash_final(shash, hash->digest);
	return rc;
	}

	static int ima_calc_file_shash(struct file file, struct ima_digest_data hash)
	{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	rc = ima_calc_file_hash_tfm(file, hash, tfm);

	ima_free_tfm(tfm);

	return rc;
	}

	/*
	* ima_calc_file_hash - calculate file hash
	*
	* Asynchronous hash (ahash) allows using HW acceleration for calculating
	* a hash. ahash performance varies for different data sizes on different
	* crypto accelerators. shash performance might be better for smaller files.
	* The 'ima.ahash_minsize' module parameter allows specifying the best
	* minimum file size for using ahash on the system.
	*
	* If the ima.ahash_minsize parameter is not specified, this function uses
	* shash for the hash calculation. If ahash fails, it falls back to using
	* shash.
	*/
	int ima_calc_file_hash(struct file file, struct ima_digest_data hash)
	{
	loff_t i_size;
	int rc;

	/*
	* For consistency, fail file's opened with the O_DIRECT flag on
	* filesystems mounted with/without DAX option.
	*/
	if (file->f_flags & O_DIRECT) {
	hash->length = hash_digest_size[ima_hash_algo];
	hash->algo = ima_hash_algo;
	return -EINVAL;
	}

	i_size = i_size_read(file_inode(file));

	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
	rc = ima_calc_file_ahash(file, hash);
	if (!rc)
	return 0;
	}

	return ima_calc_file_shash(file, hash);
	}

	/*
	* Calculate the hash of template data
	*/
	static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
	struct ima_template_desc *td,
	int num_fields,
	struct ima_digest_data *hash,
	struct crypto_shash *tfm)
	{
	SHASH_DESC_ON_STACK(shash, tfm);
	int rc, i;

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
	return rc;

	for (i = 0; i < num_fields; i++) {
	u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
	u8 *data_to_hash = field_data[i].data;
	u32 datalen = field_data[i].len;
	u32 datalen_to_hash =
	!ima_canonical_fmt ? datalen : cpu_to_le32(datalen);

	if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
	rc = crypto_shash_update(shash,
	(const u8 *) &datalen_to_hash,
	sizeof(datalen_to_hash));
	if (rc)
	break;
	} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
	memcpy(buffer, data_to_hash, datalen);
	data_to_hash = buffer;
	datalen = IMA_EVENT_NAME_LEN_MAX + 1;
	}
	rc = crypto_shash_update(shash, data_to_hash, datalen);
	if (rc)
	break;
	}

	if (!rc)
	rc = crypto_shash_final(shash, hash->digest);

	return rc;
	}

	int ima_calc_field_array_hash(struct ima_field_data *field_data,
	struct ima_template_desc *desc, int num_fields,
	struct ima_digest_data *hash)
	{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
	hash, tfm);

	ima_free_tfm(tfm);

	return rc;
	}

	static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
	struct ima_digest_data *hash,
	struct crypto_ahash *tfm)
	{
	struct ahash_request *req;
	struct scatterlist sg;
	struct crypto_wait wait;
	int rc, ahash_rc = 0;

	hash->length = crypto_ahash_digestsize(tfm);

	req = ahash_request_alloc(tfm, GFP_KERNEL);
	if (!req)
	return -ENOMEM;

	crypto_init_wait(&wait);
	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG \|
	CRYPTO_TFM_REQ_MAY_SLEEP,
	crypto_req_done, &wait);

	rc = ahash_wait(crypto_ahash_init(req), &wait);
	if (rc)
	goto out;

	sg_init_one(&sg, buf, len);
	ahash_request_set_crypt(req, &sg, NULL, len);

	ahash_rc = crypto_ahash_update(req);

	/* wait for the update request to complete */
	rc = ahash_wait(ahash_rc, &wait);
	if (!rc) {
	ahash_request_set_crypt(req, NULL, hash->digest, 0);
	rc = ahash_wait(crypto_ahash_final(req), &wait);
	}
	out:
	ahash_request_free(req);
	return rc;
	}

	static int calc_buffer_ahash(const void *buf, loff_t len,
	struct ima_digest_data *hash)
	{
	struct crypto_ahash *tfm;
	int rc;

	tfm = ima_alloc_atfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);

	ima_free_atfm(tfm);

	return rc;
	}

	static int calc_buffer_shash_tfm(const void *buf, loff_t size,
	struct ima_digest_data *hash,
	struct crypto_shash *tfm)
	{
	SHASH_DESC_ON_STACK(shash, tfm);
	unsigned int len;
	int rc;

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
	return rc;

	while (size) {
	len = size < PAGE_SIZE ? size : PAGE_SIZE;
	rc = crypto_shash_update(shash, buf, len);
	if (rc)
	break;
	buf += len;
	size -= len;
	}

	if (!rc)
	rc = crypto_shash_final(shash, hash->digest);
	return rc;
	}

	static int calc_buffer_shash(const void *buf, loff_t len,
	struct ima_digest_data *hash)
	{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	rc = calc_buffer_shash_tfm(buf, len, hash, tfm);

	ima_free_tfm(tfm);
	return rc;
	}

	int ima_calc_buffer_hash(const void *buf, loff_t len,
	struct ima_digest_data *hash)
	{
	int rc;

	if (ima_ahash_minsize && len >= ima_ahash_minsize) {
	rc = calc_buffer_ahash(buf, len, hash);
	if (!rc)
	return 0;
	}

	return calc_buffer_shash(buf, len, hash);
	}

	static void __init ima_pcrread(int idx, u8 *pcr)
	{
	if (!ima_used_chip)
	return;

	if (tpm_pcr_read(NULL, idx, pcr) != 0)
	pr_err("Error Communicating to TPM chip\n");
	}

	/*
	* Calculate the boot aggregate hash
	*/
	static int __init ima_calc_boot_aggregate_tfm(char *digest,
	struct crypto_shash *tfm)
	{
	u8 pcr_i[TPM_DIGEST_SIZE];
	int rc, i;
	SHASH_DESC_ON_STACK(shash, tfm);

	shash->tfm = tfm;
	shash->flags = 0;

	rc = crypto_shash_init(shash);
	if (rc != 0)
	return rc;

	/* cumulative sha1 over tpm registers 0-7 */
	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
	ima_pcrread(i, pcr_i);
	/* now accumulate with current aggregate */
	rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
	}
	if (!rc)
	crypto_shash_final(shash, digest);
	return rc;
	}

	int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
	{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
	return PTR_ERR(tfm);

	hash->length = crypto_shash_digestsize(tfm);
	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);

	ima_free_tfm(tfm);

	return rc;
	}