1 files changed, 882 insertions, 0 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
new file mode 100644
index 000000000..51ad29940
--- /dev/null
+++ b/security/integrity/ima/ima_crypto.c
@@ -0,0 +1,882 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2005,2006,2007,2008 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * File: ima_crypto.c
+ *	Calculates md5/sha1 file hash, template hash, boot-aggreate hash
+ */
+
+#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;
+
+struct ima_algo_desc {
+	struct crypto_shash *tfm;
+	enum hash_algo algo;
+};
+
+int ima_sha1_idx __ro_after_init;
+int ima_hash_algo_idx __ro_after_init;
+/*
+ * Additional number of slots reserved, as needed, for SHA1
+ * and IMA default algo.
+ */
+int ima_extra_slots __ro_after_init;
+
+static struct ima_algo_desc *ima_algo_array;
+
+static int __init ima_init_ima_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, i;
+
+	if (algo < 0 || algo >= HASH_ALGO__LAST)
+		algo = ima_hash_algo;
+
+	if (algo == ima_hash_algo)
+		return tfm;
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
+		if (ima_algo_array[i].tfm && ima_algo_array[i].algo == algo)
+			return ima_algo_array[i].tfm;
+
+	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;
+}
+
+int __init ima_init_crypto(void)
+{
+	enum hash_algo algo;
+	long rc;
+	int i;
+
+	rc = ima_init_ima_crypto();
+	if (rc)
+		return rc;
+
+	ima_sha1_idx = -1;
+	ima_hash_algo_idx = -1;
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip); i++) {
+		algo = ima_tpm_chip->allocated_banks[i].crypto_id;
+		if (algo == HASH_ALGO_SHA1)
+			ima_sha1_idx = i;
+
+		if (algo == ima_hash_algo)
+			ima_hash_algo_idx = i;
+	}
+
+	if (ima_sha1_idx < 0) {
+		ima_sha1_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
+		if (ima_hash_algo == HASH_ALGO_SHA1)
+			ima_hash_algo_idx = ima_sha1_idx;
+	}
+
+	if (ima_hash_algo_idx < 0)
+		ima_hash_algo_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
+
+	ima_algo_array = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots,
+				 sizeof(*ima_algo_array), GFP_KERNEL);
+	if (!ima_algo_array) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip); i++) {
+		algo = ima_tpm_chip->allocated_banks[i].crypto_id;
+		ima_algo_array[i].algo = algo;
+
+		/* unknown TPM algorithm */
+		if (algo == HASH_ALGO__LAST)
+			continue;
+
+		if (algo == ima_hash_algo) {
+			ima_algo_array[i].tfm = ima_shash_tfm;
+			continue;
+		}
+
+		ima_algo_array[i].tfm = ima_alloc_tfm(algo);
+		if (IS_ERR(ima_algo_array[i].tfm)) {
+			if (algo == HASH_ALGO_SHA1) {
+				rc = PTR_ERR(ima_algo_array[i].tfm);
+				ima_algo_array[i].tfm = NULL;
+				goto out_array;
+			}
+
+			ima_algo_array[i].tfm = NULL;
+		}
+	}
+
+	if (ima_sha1_idx >= NR_BANKS(ima_tpm_chip)) {
+		if (ima_hash_algo == HASH_ALGO_SHA1) {
+			ima_algo_array[ima_sha1_idx].tfm = ima_shash_tfm;
+		} else {
+			ima_algo_array[ima_sha1_idx].tfm =
+						ima_alloc_tfm(HASH_ALGO_SHA1);
+			if (IS_ERR(ima_algo_array[ima_sha1_idx].tfm)) {
+				rc = PTR_ERR(ima_algo_array[ima_sha1_idx].tfm);
+				goto out_array;
+			}
+		}
+
+		ima_algo_array[ima_sha1_idx].algo = HASH_ALGO_SHA1;
+	}
+
+	if (ima_hash_algo_idx >= NR_BANKS(ima_tpm_chip) &&
+	    ima_hash_algo_idx != ima_sha1_idx) {
+		ima_algo_array[ima_hash_algo_idx].tfm = ima_shash_tfm;
+		ima_algo_array[ima_hash_algo_idx].algo = ima_hash_algo;
+	}
+
+	return 0;
+out_array:
+	for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
+		if (!ima_algo_array[i].tfm ||
+		    ima_algo_array[i].tfm == ima_shash_tfm)
+			continue;
+
+		crypto_free_shash(ima_algo_array[i].tfm);
+	}
+	kfree(ima_algo_array);
+out:
+	crypto_free_shash(ima_shash_tfm);
+	return rc;
+}
+
+static void ima_free_tfm(struct crypto_shash *tfm)
+{
+	int i;
+
+	if (tfm == ima_shash_tfm)
+		return;
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
+		if (ima_algo_array[i].tfm == tfm)
+			return;
+
+	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, 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);
+	}
+
+	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) {
+			if (rc >= 0)
+				rc = -EINVAL;
+			/*
+			 * Forward current rc, do not overwrite with return value
+			 * from ahash_wait()
+			 */
+			ahash_wait(ahash_rc, &wait);
+			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:
+	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;
+	SHASH_DESC_ON_STACK(shash, tfm);
+
+	shash->tfm = tfm;
+
+	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;
+
+	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) {	/* unexpected EOF */
+			rc = -EINVAL;
+			break;
+		}
+		offset += rbuf_len;
+
+		rc = crypto_shash_update(shash, rbuf, rbuf_len);
+		if (rc)
+			break;
+	}
+	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;
+	struct file *f = file;
+	bool new_file_instance = false;
+
+	/*
+	 * 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;
+	}
+
+	/* Open a new file instance in O_RDONLY if we cannot read */
+	if (!(file->f_mode & FMODE_READ)) {
+		int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
+				O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
+		flags |= O_RDONLY;
+		f = dentry_open(&file->f_path, flags, file->f_cred);
+		if (IS_ERR(f))
+			return PTR_ERR(f);
+
+		new_file_instance = true;
+	}
+
+	i_size = i_size_read(file_inode(f));
+
+	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
+		rc = ima_calc_file_ahash(f, hash);
+		if (!rc)
+			goto out;
+	}
+
+	rc = ima_calc_file_shash(f, hash);
+out:
+	if (new_file_instance)
+		fput(f);
+	return rc;
+}
+
+/*
+ * Calculate the hash of template data
+ */
+static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
+					 struct ima_template_entry *entry,
+					 int tfm_idx)
+{
+	SHASH_DESC_ON_STACK(shash, ima_algo_array[tfm_idx].tfm);
+	struct ima_template_desc *td = entry->template_desc;
+	int num_fields = entry->template_desc->num_fields;
+	int rc, i;
+
+	shash->tfm = ima_algo_array[tfm_idx].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 : (__force u32)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, entry->digests[tfm_idx].digest);
+
+	return rc;
+}
+
+int ima_calc_field_array_hash(struct ima_field_data *field_data,
+			      struct ima_template_entry *entry)
+{
+	u16 alg_id;
+	int rc, i;
+
+	rc = ima_calc_field_array_hash_tfm(field_data, entry, ima_sha1_idx);
+	if (rc)
+		return rc;
+
+	entry->digests[ima_sha1_idx].alg_id = TPM_ALG_SHA1;
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
+		if (i == ima_sha1_idx)
+			continue;
+
+		if (i < NR_BANKS(ima_tpm_chip)) {
+			alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
+			entry->digests[i].alg_id = alg_id;
+		}
+
+		/* for unmapped TPM algorithms digest is still a padded SHA1 */
+		if (!ima_algo_array[i].tfm) {
+			memcpy(entry->digests[i].digest,
+			       entry->digests[ima_sha1_idx].digest,
+			       TPM_DIGEST_SIZE);
+			continue;
+		}
+
+		rc = ima_calc_field_array_hash_tfm(field_data, entry, i);
+		if (rc)
+			return rc;
+	}
+	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;
+
+	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 ima_pcrread(u32 idx, struct tpm_digest *d)
+{
+	if (!ima_tpm_chip)
+		return;
+
+	if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
+		pr_err("Error Communicating to TPM chip\n");
+}
+
+/*
+ * The boot_aggregate is a cumulative hash over TPM registers 0 - 7.  With
+ * TPM 1.2 the boot_aggregate was based on reading the SHA1 PCRs, but with
+ * TPM 2.0 hash agility, TPM chips could support multiple TPM PCR banks,
+ * allowing firmware to configure and enable different banks.
+ *
+ * Knowing which TPM bank is read to calculate the boot_aggregate digest
+ * needs to be conveyed to a verifier.  For this reason, use the same
+ * hash algorithm for reading the TPM PCRs as for calculating the boot
+ * aggregate digest as stored in the measurement list.
+ */
+static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
+				       struct crypto_shash *tfm)
+{
+	struct tpm_digest d = { .alg_id = alg_id, .digest = {0} };
+	int rc;
+	u32 i;
+	SHASH_DESC_ON_STACK(shash, tfm);
+
+	shash->tfm = tfm;
+
+	pr_devel("calculating the boot-aggregate based on TPM bank: %04x\n",
+		 d.alg_id);
+
+	rc = crypto_shash_init(shash);
+	if (rc != 0)
+		return rc;
+
+	/* cumulative digest over TPM registers 0-7 */
+	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
+		ima_pcrread(i, &d);
+		/* now accumulate with current aggregate */
+		rc = crypto_shash_update(shash, d.digest,
+					 crypto_shash_digestsize(tfm));
+		if (rc != 0)
+			return rc;
+	}
+	/*
+	 * Extend cumulative digest over TPM registers 8-9, which contain
+	 * measurement for the kernel command line (reg. 8) and image (reg. 9)
+	 * in a typical PCR allocation. Registers 8-9 are only included in
+	 * non-SHA1 boot_aggregate digests to avoid ambiguity.
+	 */
+	if (alg_id != TPM_ALG_SHA1) {
+		for (i = TPM_PCR8; i < TPM_PCR10; i++) {
+			ima_pcrread(i, &d);
+			rc = crypto_shash_update(shash, d.digest,
+						crypto_shash_digestsize(tfm));
+		}
+	}
+	if (!rc)
+		crypto_shash_final(shash, digest);
+	return rc;
+}
+
+int ima_calc_boot_aggregate(struct ima_digest_data *hash)
+{
+	struct crypto_shash *tfm;
+	u16 crypto_id, alg_id;
+	int rc, i, bank_idx = -1;
+
+	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
+		crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
+		if (crypto_id == hash->algo) {
+			bank_idx = i;
+			break;
+		}
+
+		if (crypto_id == HASH_ALGO_SHA256)
+			bank_idx = i;
+
+		if (bank_idx == -1 && crypto_id == HASH_ALGO_SHA1)
+			bank_idx = i;
+	}
+
+	if (bank_idx == -1) {
+		pr_err("No suitable TPM algorithm for boot aggregate\n");
+		return 0;
+	}
+
+	hash->algo = ima_tpm_chip->allocated_banks[bank_idx].crypto_id;
+
+	tfm = ima_alloc_tfm(hash->algo);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	hash->length = crypto_shash_digestsize(tfm);
+	alg_id = ima_tpm_chip->allocated_banks[bank_idx].alg_id;
+	rc = ima_calc_boot_aggregate_tfm(hash->digest, alg_id, tfm);
+
+	ima_free_tfm(tfm);
+
+	return rc;
+}