Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2108 insertions, 0 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
new file mode 100644
index 000000000..e3f5d7f3c
--- /dev/null
+++ b/fs/ecryptfs/crypto.c
@@ -0,0 +1,2108 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2004 Erez Zadok
+ * Copyright (C) 2001-2004 Stony Brook University
+ * Copyright (C) 2004-2007 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
+ *   		Michael C. Thompson <mcthomps@us.ibm.com>
+ */
+
+#include <crypto/hash.h>
+#include <crypto/skcipher.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/random.h>
+#include <linux/compiler.h>
+#include <linux/key.h>
+#include <linux/namei.h>
+#include <linux/file.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <asm/unaligned.h>
+#include <linux/kernel.h>
+#include <linux/xattr.h>
+#include "ecryptfs_kernel.h"
+
+#define DECRYPT		0
+#define ENCRYPT		1
+
+/**
+ * ecryptfs_from_hex
+ * @dst: Buffer to take the bytes from src hex; must be at least of
+ *       size (src_size / 2)
+ * @src: Buffer to be converted from a hex string representation to raw value
+ * @dst_size: size of dst buffer, or number of hex characters pairs to convert
+ */
+void ecryptfs_from_hex(char *dst, char *src, int dst_size)
+{
+	int x;
+	char tmp[3] = { 0, };
+
+	for (x = 0; x < dst_size; x++) {
+		tmp[0] = src[x * 2];
+		tmp[1] = src[x * 2 + 1];
+		dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
+	}
+}
+
+/**
+ * ecryptfs_calculate_md5 - calculates the md5 of @src
+ * @dst: Pointer to 16 bytes of allocated memory
+ * @crypt_stat: Pointer to crypt_stat struct for the current inode
+ * @src: Data to be md5'd
+ * @len: Length of @src
+ *
+ * Uses the allocated crypto context that crypt_stat references to
+ * generate the MD5 sum of the contents of src.
+ */
+static int ecryptfs_calculate_md5(char *dst,
+				  struct ecryptfs_crypt_stat *crypt_stat,
+				  char *src, int len)
+{
+	int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
+
+	if (rc) {
+		printk(KERN_ERR
+		       "%s: Error computing crypto hash; rc = [%d]\n",
+		       __func__, rc);
+		goto out;
+	}
+out:
+	return rc;
+}
+
+static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
+						  char *cipher_name,
+						  char *chaining_modifier)
+{
+	int cipher_name_len = strlen(cipher_name);
+	int chaining_modifier_len = strlen(chaining_modifier);
+	int algified_name_len;
+	int rc;
+
+	algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
+	(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
+	if (!(*algified_name)) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	snprintf((*algified_name), algified_name_len, "%s(%s)",
+		 chaining_modifier, cipher_name);
+	rc = 0;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_derive_iv
+ * @iv: destination for the derived iv vale
+ * @crypt_stat: Pointer to crypt_stat struct for the current inode
+ * @offset: Offset of the extent whose IV we are to derive
+ *
+ * Generate the initialization vector from the given root IV and page
+ * offset.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
+		       loff_t offset)
+{
+	int rc = 0;
+	char dst[MD5_DIGEST_SIZE];
+	char src[ECRYPTFS_MAX_IV_BYTES + 16];
+
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "root iv:\n");
+		ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
+	}
+	/* TODO: It is probably secure to just cast the least
+	 * significant bits of the root IV into an unsigned long and
+	 * add the offset to that rather than go through all this
+	 * hashing business. -Halcrow */
+	memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
+	memset((src + crypt_stat->iv_bytes), 0, 16);
+	snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "source:\n");
+		ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
+	}
+	rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
+				    (crypt_stat->iv_bytes + 16));
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
+				"MD5 while generating IV for a page\n");
+		goto out;
+	}
+	memcpy(iv, dst, crypt_stat->iv_bytes);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
+		ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_init_crypt_stat
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ *
+ * Initialize the crypt_stat structure.
+ */
+int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	struct crypto_shash *tfm;
+	int rc;
+
+	tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
+	if (IS_ERR(tfm)) {
+		rc = PTR_ERR(tfm);
+		ecryptfs_printk(KERN_ERR, "Error attempting to "
+				"allocate crypto context; rc = [%d]\n",
+				rc);
+		return rc;
+	}
+
+	memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
+	INIT_LIST_HEAD(&crypt_stat->keysig_list);
+	mutex_init(&crypt_stat->keysig_list_mutex);
+	mutex_init(&crypt_stat->cs_mutex);
+	mutex_init(&crypt_stat->cs_tfm_mutex);
+	crypt_stat->hash_tfm = tfm;
+	crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
+
+	return 0;
+}
+
+/**
+ * ecryptfs_destroy_crypt_stat
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ *
+ * Releases all memory associated with a crypt_stat struct.
+ */
+void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
+
+	crypto_free_skcipher(crypt_stat->tfm);
+	crypto_free_shash(crypt_stat->hash_tfm);
+	list_for_each_entry_safe(key_sig, key_sig_tmp,
+				 &crypt_stat->keysig_list, crypt_stat_list) {
+		list_del(&key_sig->crypt_stat_list);
+		kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
+	}
+	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
+}
+
+void ecryptfs_destroy_mount_crypt_stat(
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
+
+	if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
+		return;
+	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
+	list_for_each_entry_safe(auth_tok, auth_tok_tmp,
+				 &mount_crypt_stat->global_auth_tok_list,
+				 mount_crypt_stat_list) {
+		list_del(&auth_tok->mount_crypt_stat_list);
+		if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
+			key_put(auth_tok->global_auth_tok_key);
+		kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
+	}
+	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
+	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
+}
+
+/**
+ * virt_to_scatterlist
+ * @addr: Virtual address
+ * @size: Size of data; should be an even multiple of the block size
+ * @sg: Pointer to scatterlist array; set to NULL to obtain only
+ *      the number of scatterlist structs required in array
+ * @sg_size: Max array size
+ *
+ * Fills in a scatterlist array with page references for a passed
+ * virtual address.
+ *
+ * Returns the number of scatterlist structs in array used
+ */
+int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
+			int sg_size)
+{
+	int i = 0;
+	struct page *pg;
+	int offset;
+	int remainder_of_page;
+
+	sg_init_table(sg, sg_size);
+
+	while (size > 0 && i < sg_size) {
+		pg = virt_to_page(addr);
+		offset = offset_in_page(addr);
+		sg_set_page(&sg[i], pg, 0, offset);
+		remainder_of_page = PAGE_SIZE - offset;
+		if (size >= remainder_of_page) {
+			sg[i].length = remainder_of_page;
+			addr += remainder_of_page;
+			size -= remainder_of_page;
+		} else {
+			sg[i].length = size;
+			addr += size;
+			size = 0;
+		}
+		i++;
+	}
+	if (size > 0)
+		return -ENOMEM;
+	return i;
+}
+
+struct extent_crypt_result {
+	struct completion completion;
+	int rc;
+};
+
+static void extent_crypt_complete(struct crypto_async_request *req, int rc)
+{
+	struct extent_crypt_result *ecr = req->data;
+
+	if (rc == -EINPROGRESS)
+		return;
+
+	ecr->rc = rc;
+	complete(&ecr->completion);
+}
+
+/**
+ * crypt_scatterlist
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ * @dst_sg: Destination of the data after performing the crypto operation
+ * @src_sg: Data to be encrypted or decrypted
+ * @size: Length of data
+ * @iv: IV to use
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
+ *
+ * Returns the number of bytes encrypted or decrypted; negative value on error
+ */
+static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct scatterlist *dst_sg,
+			     struct scatterlist *src_sg, int size,
+			     unsigned char *iv, int op)
+{
+	struct skcipher_request *req = NULL;
+	struct extent_crypt_result ecr;
+	int rc = 0;
+
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
+				crypt_stat->key_size);
+		ecryptfs_dump_hex(crypt_stat->key,
+				  crypt_stat->key_size);
+	}
+
+	init_completion(&ecr.completion);
+
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
+	req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
+	if (!req) {
+		mutex_unlock(&crypt_stat->cs_tfm_mutex);
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	skcipher_request_set_callback(req,
+			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+			extent_crypt_complete, &ecr);
+	/* Consider doing this once, when the file is opened */
+	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
+		rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
+					    crypt_stat->key_size);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR,
+					"Error setting key; rc = [%d]\n",
+					rc);
+			mutex_unlock(&crypt_stat->cs_tfm_mutex);
+			rc = -EINVAL;
+			goto out;
+		}
+		crypt_stat->flags |= ECRYPTFS_KEY_SET;
+	}
+	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+	skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
+	rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
+			     crypto_skcipher_decrypt(req);
+	if (rc == -EINPROGRESS || rc == -EBUSY) {
+		struct extent_crypt_result *ecr = req->base.data;
+
+		wait_for_completion(&ecr->completion);
+		rc = ecr->rc;
+		reinit_completion(&ecr->completion);
+	}
+out:
+	skcipher_request_free(req);
+	return rc;
+}
+
+/*
+ * lower_offset_for_page
+ *
+ * Convert an eCryptfs page index into a lower byte offset
+ */
+static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
+				    struct page *page)
+{
+	return ecryptfs_lower_header_size(crypt_stat) +
+	       ((loff_t)page->index << PAGE_SHIFT);
+}
+
+/**
+ * crypt_extent
+ * @crypt_stat: crypt_stat containing cryptographic context for the
+ *              encryption operation
+ * @dst_page: The page to write the result into
+ * @src_page: The page to read from
+ * @extent_offset: Page extent offset for use in generating IV
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
+ *
+ * Encrypts or decrypts one extent of data.
+ *
+ * Return zero on success; non-zero otherwise
+ */
+static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
+			struct page *dst_page,
+			struct page *src_page,
+			unsigned long extent_offset, int op)
+{
+	pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
+	loff_t extent_base;
+	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
+	struct scatterlist src_sg, dst_sg;
+	size_t extent_size = crypt_stat->extent_size;
+	int rc;
+
+	extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
+	rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
+				(extent_base + extent_offset));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
+			"extent [0x%.16llx]; rc = [%d]\n",
+			(unsigned long long)(extent_base + extent_offset), rc);
+		goto out;
+	}
+
+	sg_init_table(&src_sg, 1);
+	sg_init_table(&dst_sg, 1);
+
+	sg_set_page(&src_sg, src_page, extent_size,
+		    extent_offset * extent_size);
+	sg_set_page(&dst_sg, dst_page, extent_size,
+		    extent_offset * extent_size);
+
+	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
+			       extent_iv, op);
+	if (rc < 0) {
+		printk(KERN_ERR "%s: Error attempting to crypt page with "
+		       "page_index = [%ld], extent_offset = [%ld]; "
+		       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
+		goto out;
+	}
+	rc = 0;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_encrypt_page
+ * @page: Page mapped from the eCryptfs inode for the file; contains
+ *        decrypted content that needs to be encrypted (to a temporary
+ *        page; not in place) and written out to the lower file
+ *
+ * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
+ * that eCryptfs pages may straddle the lower pages -- for instance,
+ * if the file was created on a machine with an 8K page size
+ * (resulting in an 8K header), and then the file is copied onto a
+ * host with a 32K page size, then when reading page 0 of the eCryptfs
+ * file, 24K of page 0 of the lower file will be read and decrypted,
+ * and then 8K of page 1 of the lower file will be read and decrypted.
+ *
+ * Returns zero on success; negative on error
+ */
+int ecryptfs_encrypt_page(struct page *page)
+{
+	struct inode *ecryptfs_inode;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	char *enc_extent_virt;
+	struct page *enc_extent_page = NULL;
+	loff_t extent_offset;
+	loff_t lower_offset;
+	int rc = 0;
+
+	ecryptfs_inode = page->mapping->host;
+	crypt_stat =
+		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
+	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
+	enc_extent_page = alloc_page(GFP_USER);
+	if (!enc_extent_page) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error allocating memory for "
+				"encrypted extent\n");
+		goto out;
+	}
+
+	for (extent_offset = 0;
+	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
+	     extent_offset++) {
+		rc = crypt_extent(crypt_stat, enc_extent_page, page,
+				  extent_offset, ENCRYPT);
+		if (rc) {
+			printk(KERN_ERR "%s: Error encrypting extent; "
+			       "rc = [%d]\n", __func__, rc);
+			goto out;
+		}
+	}
+
+	lower_offset = lower_offset_for_page(crypt_stat, page);
+	enc_extent_virt = kmap(enc_extent_page);
+	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
+				  PAGE_SIZE);
+	kunmap(enc_extent_page);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR,
+			"Error attempting to write lower page; rc = [%d]\n",
+			rc);
+		goto out;
+	}
+	rc = 0;
+out:
+	if (enc_extent_page) {
+		__free_page(enc_extent_page);
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_decrypt_page
+ * @page: Page mapped from the eCryptfs inode for the file; data read
+ *        and decrypted from the lower file will be written into this
+ *        page
+ *
+ * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
+ * that eCryptfs pages may straddle the lower pages -- for instance,
+ * if the file was created on a machine with an 8K page size
+ * (resulting in an 8K header), and then the file is copied onto a
+ * host with a 32K page size, then when reading page 0 of the eCryptfs
+ * file, 24K of page 0 of the lower file will be read and decrypted,
+ * and then 8K of page 1 of the lower file will be read and decrypted.
+ *
+ * Returns zero on success; negative on error
+ */
+int ecryptfs_decrypt_page(struct page *page)
+{
+	struct inode *ecryptfs_inode;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	char *page_virt;
+	unsigned long extent_offset;
+	loff_t lower_offset;
+	int rc = 0;
+
+	ecryptfs_inode = page->mapping->host;
+	crypt_stat =
+		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
+	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
+
+	lower_offset = lower_offset_for_page(crypt_stat, page);
+	page_virt = kmap(page);
+	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
+				 ecryptfs_inode);
+	kunmap(page);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR,
+			"Error attempting to read lower page; rc = [%d]\n",
+			rc);
+		goto out;
+	}
+
+	for (extent_offset = 0;
+	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
+	     extent_offset++) {
+		rc = crypt_extent(crypt_stat, page, page,
+				  extent_offset, DECRYPT);
+		if (rc) {
+			printk(KERN_ERR "%s: Error decrypting extent; "
+			       "rc = [%d]\n", __func__, rc);
+			goto out;
+		}
+	}
+out:
+	return rc;
+}
+
+#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
+
+/**
+ * ecryptfs_init_crypt_ctx
+ * @crypt_stat: Uninitialized crypt stats structure
+ *
+ * Initialize the crypto context.
+ *
+ * TODO: Performance: Keep a cache of initialized cipher contexts;
+ * only init if needed
+ */
+int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	char *full_alg_name;
+	int rc = -EINVAL;
+
+	ecryptfs_printk(KERN_DEBUG,
+			"Initializing cipher [%s]; strlen = [%d]; "
+			"key_size_bits = [%zd]\n",
+			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
+			crypt_stat->key_size << 3);
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
+	if (crypt_stat->tfm) {
+		rc = 0;
+		goto out_unlock;
+	}
+	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
+						    crypt_stat->cipher, "cbc");
+	if (rc)
+		goto out_unlock;
+	crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
+	if (IS_ERR(crypt_stat->tfm)) {
+		rc = PTR_ERR(crypt_stat->tfm);
+		crypt_stat->tfm = NULL;
+		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
+				"Error initializing cipher [%s]\n",
+				full_alg_name);
+		goto out_free;
+	}
+	crypto_skcipher_set_flags(crypt_stat->tfm,
+				  CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
+	rc = 0;
+out_free:
+	kfree(full_alg_name);
+out_unlock:
+	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+	return rc;
+}
+
+static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int extent_size_tmp;
+
+	crypt_stat->extent_mask = 0xFFFFFFFF;
+	crypt_stat->extent_shift = 0;
+	if (crypt_stat->extent_size == 0)
+		return;
+	extent_size_tmp = crypt_stat->extent_size;
+	while ((extent_size_tmp & 0x01) == 0) {
+		extent_size_tmp >>= 1;
+		crypt_stat->extent_mask <<= 1;
+		crypt_stat->extent_shift++;
+	}
+}
+
+void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	/* Default values; may be overwritten as we are parsing the
+	 * packets. */
+	crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
+	set_extent_mask_and_shift(crypt_stat);
+	crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
+	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+		crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
+	else {
+		if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
+			crypt_stat->metadata_size =
+				ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
+		else
+			crypt_stat->metadata_size = PAGE_SIZE;
+	}
+}
+
+/*
+ * ecryptfs_compute_root_iv
+ *
+ * On error, sets the root IV to all 0's.
+ */
+int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int rc = 0;
+	char dst[MD5_DIGEST_SIZE];
+
+	BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
+	BUG_ON(crypt_stat->iv_bytes <= 0);
+	if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_WARNING, "Session key not valid; "
+				"cannot generate root IV\n");
+		goto out;
+	}
+	rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
+				    crypt_stat->key_size);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
+				"MD5 while generating root IV\n");
+		goto out;
+	}
+	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
+out:
+	if (rc) {
+		memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
+		crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
+	}
+	return rc;
+}
+
+static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	get_random_bytes(crypt_stat->key, crypt_stat->key_size);
+	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
+	ecryptfs_compute_root_iv(crypt_stat);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
+		ecryptfs_dump_hex(crypt_stat->key,
+				  crypt_stat->key_size);
+	}
+}
+
+/**
+ * ecryptfs_copy_mount_wide_flags_to_inode_flags
+ * @crypt_stat: The inode's cryptographic context
+ * @mount_crypt_stat: The mount point's cryptographic context
+ *
+ * This function propagates the mount-wide flags to individual inode
+ * flags.
+ */
+static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
+	struct ecryptfs_crypt_stat *crypt_stat,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
+		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
+	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
+		crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
+	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
+		crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
+		if (mount_crypt_stat->flags
+		    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
+			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
+		else if (mount_crypt_stat->flags
+			 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
+			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
+	}
+}
+
+static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
+	struct ecryptfs_crypt_stat *crypt_stat,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	struct ecryptfs_global_auth_tok *global_auth_tok;
+	int rc = 0;
+
+	mutex_lock(&crypt_stat->keysig_list_mutex);
+	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
+
+	list_for_each_entry(global_auth_tok,
+			    &mount_crypt_stat->global_auth_tok_list,
+			    mount_crypt_stat_list) {
+		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
+			continue;
+		rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
+		if (rc) {
+			printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
+			goto out;
+		}
+	}
+
+out:
+	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
+	mutex_unlock(&crypt_stat->keysig_list_mutex);
+	return rc;
+}
+
+/**
+ * ecryptfs_set_default_crypt_stat_vals
+ * @crypt_stat: The inode's cryptographic context
+ * @mount_crypt_stat: The mount point's cryptographic context
+ *
+ * Default values in the event that policy does not override them.
+ */
+static void ecryptfs_set_default_crypt_stat_vals(
+	struct ecryptfs_crypt_stat *crypt_stat,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
+						      mount_crypt_stat);
+	ecryptfs_set_default_sizes(crypt_stat);
+	strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
+	crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
+	crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
+	crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
+	crypt_stat->mount_crypt_stat = mount_crypt_stat;
+}
+
+/**
+ * ecryptfs_new_file_context
+ * @ecryptfs_inode: The eCryptfs inode
+ *
+ * If the crypto context for the file has not yet been established,
+ * this is where we do that.  Establishing a new crypto context
+ * involves the following decisions:
+ *  - What cipher to use?
+ *  - What set of authentication tokens to use?
+ * Here we just worry about getting enough information into the
+ * authentication tokens so that we know that they are available.
+ * We associate the available authentication tokens with the new file
+ * via the set of signatures in the crypt_stat struct.  Later, when
+ * the headers are actually written out, we may again defer to
+ * userspace to perform the encryption of the session key; for the
+ * foreseeable future, this will be the case with public key packets.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
+{
+	struct ecryptfs_crypt_stat *crypt_stat =
+	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+	    &ecryptfs_superblock_to_private(
+		    ecryptfs_inode->i_sb)->mount_crypt_stat;
+	int cipher_name_len;
+	int rc = 0;
+
+	ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
+	crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
+	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
+						      mount_crypt_stat);
+	rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
+							 mount_crypt_stat);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
+		       "to the inode key sigs; rc = [%d]\n", rc);
+		goto out;
+	}
+	cipher_name_len =
+		strlen(mount_crypt_stat->global_default_cipher_name);
+	memcpy(crypt_stat->cipher,
+	       mount_crypt_stat->global_default_cipher_name,
+	       cipher_name_len);
+	crypt_stat->cipher[cipher_name_len] = '\0';
+	crypt_stat->key_size =
+		mount_crypt_stat->global_default_cipher_key_size;
+	ecryptfs_generate_new_key(crypt_stat);
+	rc = ecryptfs_init_crypt_ctx(crypt_stat);
+	if (rc)
+		ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
+				"context for cipher [%s]: rc = [%d]\n",
+				crypt_stat->cipher, rc);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_validate_marker - check for the ecryptfs marker
+ * @data: The data block in which to check
+ *
+ * Returns zero if marker found; -EINVAL if not found
+ */
+static int ecryptfs_validate_marker(char *data)
+{
+	u32 m_1, m_2;
+
+	m_1 = get_unaligned_be32(data);
+	m_2 = get_unaligned_be32(data + 4);
+	if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
+		return 0;
+	ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
+			"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
+			MAGIC_ECRYPTFS_MARKER);
+	ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
+			"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
+	return -EINVAL;
+}
+
+struct ecryptfs_flag_map_elem {
+	u32 file_flag;
+	u32 local_flag;
+};
+
+/* Add support for additional flags by adding elements here. */
+static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
+	{0x00000001, ECRYPTFS_ENABLE_HMAC},
+	{0x00000002, ECRYPTFS_ENCRYPTED},
+	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
+	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
+};
+
+/**
+ * ecryptfs_process_flags
+ * @crypt_stat: The cryptographic context
+ * @page_virt: Source data to be parsed
+ * @bytes_read: Updated with the number of bytes read
+ */
+static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
+				  char *page_virt, int *bytes_read)
+{
+	int i;
+	u32 flags;
+
+	flags = get_unaligned_be32(page_virt);
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
+		if (flags & ecryptfs_flag_map[i].file_flag) {
+			crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
+		} else
+			crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
+	/* Version is in top 8 bits of the 32-bit flag vector */
+	crypt_stat->file_version = ((flags >> 24) & 0xFF);
+	(*bytes_read) = 4;
+}
+
+/**
+ * write_ecryptfs_marker
+ * @page_virt: The pointer to in a page to begin writing the marker
+ * @written: Number of bytes written
+ *
+ * Marker = 0x3c81b7f5
+ */
+static void write_ecryptfs_marker(char *page_virt, size_t *written)
+{
+	u32 m_1, m_2;
+
+	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
+	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
+	put_unaligned_be32(m_1, page_virt);
+	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
+	put_unaligned_be32(m_2, page_virt);
+	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
+}
+
+void ecryptfs_write_crypt_stat_flags(char *page_virt,
+				     struct ecryptfs_crypt_stat *crypt_stat,
+				     size_t *written)
+{
+	u32 flags = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
+		if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
+			flags |= ecryptfs_flag_map[i].file_flag;
+	/* Version is in top 8 bits of the 32-bit flag vector */
+	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
+	put_unaligned_be32(flags, page_virt);
+	(*written) = 4;
+}
+
+struct ecryptfs_cipher_code_str_map_elem {
+	char cipher_str[16];
+	u8 cipher_code;
+};
+
+/* Add support for additional ciphers by adding elements here. The
+ * cipher_code is whatever OpenPGP applications use to identify the
+ * ciphers. List in order of probability. */
+static struct ecryptfs_cipher_code_str_map_elem
+ecryptfs_cipher_code_str_map[] = {
+	{"aes",RFC2440_CIPHER_AES_128 },
+	{"blowfish", RFC2440_CIPHER_BLOWFISH},
+	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
+	{"cast5", RFC2440_CIPHER_CAST_5},
+	{"twofish", RFC2440_CIPHER_TWOFISH},
+	{"cast6", RFC2440_CIPHER_CAST_6},
+	{"aes", RFC2440_CIPHER_AES_192},
+	{"aes", RFC2440_CIPHER_AES_256}
+};
+
+/**
+ * ecryptfs_code_for_cipher_string
+ * @cipher_name: The string alias for the cipher
+ * @key_bytes: Length of key in bytes; used for AES code selection
+ *
+ * Returns zero on no match, or the cipher code on match
+ */
+u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
+{
+	int i;
+	u8 code = 0;
+	struct ecryptfs_cipher_code_str_map_elem *map =
+		ecryptfs_cipher_code_str_map;
+
+	if (strcmp(cipher_name, "aes") == 0) {
+		switch (key_bytes) {
+		case 16:
+			code = RFC2440_CIPHER_AES_128;
+			break;
+		case 24:
+			code = RFC2440_CIPHER_AES_192;
+			break;
+		case 32:
+			code = RFC2440_CIPHER_AES_256;
+		}
+	} else {
+		for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
+			if (strcmp(cipher_name, map[i].cipher_str) == 0) {
+				code = map[i].cipher_code;
+				break;
+			}
+	}
+	return code;
+}
+
+/**
+ * ecryptfs_cipher_code_to_string
+ * @str: Destination to write out the cipher name
+ * @cipher_code: The code to convert to cipher name string
+ *
+ * Returns zero on success
+ */
+int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
+{
+	int rc = 0;
+	int i;
+
+	str[0] = '\0';
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
+		if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
+			strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
+	if (str[0] == '\0') {
+		ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
+				"[%d]\n", cipher_code);
+		rc = -EINVAL;
+	}
+	return rc;
+}
+
+int ecryptfs_read_and_validate_header_region(struct inode *inode)
+{
+	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
+	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
+	int rc;
+
+	rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
+				 inode);
+	if (rc < 0)
+		return rc;
+	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
+		return -EINVAL;
+	rc = ecryptfs_validate_marker(marker);
+	if (!rc)
+		ecryptfs_i_size_init(file_size, inode);
+	return rc;
+}
+
+void
+ecryptfs_write_header_metadata(char *virt,
+			       struct ecryptfs_crypt_stat *crypt_stat,
+			       size_t *written)
+{
+	u32 header_extent_size;
+	u16 num_header_extents_at_front;
+
+	header_extent_size = (u32)crypt_stat->extent_size;
+	num_header_extents_at_front =
+		(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
+	put_unaligned_be32(header_extent_size, virt);
+	virt += 4;
+	put_unaligned_be16(num_header_extents_at_front, virt);
+	(*written) = 6;
+}
+
+struct kmem_cache *ecryptfs_header_cache;
+
+/**
+ * ecryptfs_write_headers_virt
+ * @page_virt: The virtual address to write the headers to
+ * @max: The size of memory allocated at page_virt
+ * @size: Set to the number of bytes written by this function
+ * @crypt_stat: The cryptographic context
+ * @ecryptfs_dentry: The eCryptfs dentry
+ *
+ * Format version: 1
+ *
+ *   Header Extent:
+ *     Octets 0-7:        Unencrypted file size (big-endian)
+ *     Octets 8-15:       eCryptfs special marker
+ *     Octets 16-19:      Flags
+ *      Octet 16:         File format version number (between 0 and 255)
+ *      Octets 17-18:     Reserved
+ *      Octet 19:         Bit 1 (lsb): Reserved
+ *                        Bit 2: Encrypted?
+ *                        Bits 3-8: Reserved
+ *     Octets 20-23:      Header extent size (big-endian)
+ *     Octets 24-25:      Number of header extents at front of file
+ *                        (big-endian)
+ *     Octet  26:         Begin RFC 2440 authentication token packet set
+ *   Data Extent 0:
+ *     Lower data (CBC encrypted)
+ *   Data Extent 1:
+ *     Lower data (CBC encrypted)
+ *   ...
+ *
+ * Returns zero on success
+ */
+static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
+				       size_t *size,
+				       struct ecryptfs_crypt_stat *crypt_stat,
+				       struct dentry *ecryptfs_dentry)
+{
+	int rc;
+	size_t written;
+	size_t offset;
+
+	offset = ECRYPTFS_FILE_SIZE_BYTES;
+	write_ecryptfs_marker((page_virt + offset), &written);
+	offset += written;
+	ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
+					&written);
+	offset += written;
+	ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
+				       &written);
+	offset += written;
+	rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
+					      ecryptfs_dentry, &written,
+					      max - offset);
+	if (rc)
+		ecryptfs_printk(KERN_WARNING, "Error generating key packet "
+				"set; rc = [%d]\n", rc);
+	if (size) {
+		offset += written;
+		*size = offset;
+	}
+	return rc;
+}
+
+static int
+ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
+				    char *virt, size_t virt_len)
+{
+	int rc;
+
+	rc = ecryptfs_write_lower(ecryptfs_inode, virt,
+				  0, virt_len);
+	if (rc < 0)
+		printk(KERN_ERR "%s: Error attempting to write header "
+		       "information to lower file; rc = [%d]\n", __func__, rc);
+	else
+		rc = 0;
+	return rc;
+}
+
+static int
+ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
+				 struct inode *ecryptfs_inode,
+				 char *page_virt, size_t size)
+{
+	int rc;
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	struct inode *lower_inode = d_inode(lower_dentry);
+
+	if (!(lower_inode->i_opflags & IOP_XATTR)) {
+		rc = -EOPNOTSUPP;
+		goto out;
+	}
+
+	inode_lock(lower_inode);
+	rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
+			    ECRYPTFS_XATTR_NAME, page_virt, size, 0);
+	if (!rc && ecryptfs_inode)
+		fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
+	inode_unlock(lower_inode);
+out:
+	return rc;
+}
+
+static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
+					       unsigned int order)
+{
+	struct page *page;
+
+	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
+	if (page)
+		return (unsigned long) page_address(page);
+	return 0;
+}
+
+/**
+ * ecryptfs_write_metadata
+ * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
+ * @ecryptfs_inode: The newly created eCryptfs inode
+ *
+ * Write the file headers out.  This will likely involve a userspace
+ * callout, in which the session key is encrypted with one or more
+ * public keys and/or the passphrase necessary to do the encryption is
+ * retrieved via a prompt.  Exactly what happens at this point should
+ * be policy-dependent.
+ *
+ * Returns zero on success; non-zero on error
+ */
+int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
+			    struct inode *ecryptfs_inode)
+{
+	struct ecryptfs_crypt_stat *crypt_stat =
+		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
+	unsigned int order;
+	char *virt;
+	size_t virt_len;
+	size_t size = 0;
+	int rc = 0;
+
+	if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+		if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
+			printk(KERN_ERR "Key is invalid; bailing out\n");
+			rc = -EINVAL;
+			goto out;
+		}
+	} else {
+		printk(KERN_WARNING "%s: Encrypted flag not set\n",
+		       __func__);
+		rc = -EINVAL;
+		goto out;
+	}
+	virt_len = crypt_stat->metadata_size;
+	order = get_order(virt_len);
+	/* Released in this function */
+	virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
+	if (!virt) {
+		printk(KERN_ERR "%s: Out of memory\n", __func__);
+		rc = -ENOMEM;
+		goto out;
+	}
+	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
+	rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
+					 ecryptfs_dentry);
+	if (unlikely(rc)) {
+		printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
+		       __func__, rc);
+		goto out_free;
+	}
+	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+		rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
+						      virt, size);
+	else
+		rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
+							 virt_len);
+	if (rc) {
+		printk(KERN_ERR "%s: Error writing metadata out to lower file; "
+		       "rc = [%d]\n", __func__, rc);
+		goto out_free;
+	}
+out_free:
+	free_pages((unsigned long)virt, order);
+out:
+	return rc;
+}
+
+#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
+#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
+static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
+				 char *virt, int *bytes_read,
+				 int validate_header_size)
+{
+	int rc = 0;
+	u32 header_extent_size;
+	u16 num_header_extents_at_front;
+
+	header_extent_size = get_unaligned_be32(virt);
+	virt += sizeof(__be32);
+	num_header_extents_at_front = get_unaligned_be16(virt);
+	crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
+				     * (size_t)header_extent_size));
+	(*bytes_read) = (sizeof(__be32) + sizeof(__be16));
+	if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
+	    && (crypt_stat->metadata_size
+		< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
+		rc = -EINVAL;
+		printk(KERN_WARNING "Invalid header size: [%zd]\n",
+		       crypt_stat->metadata_size);
+	}
+	return rc;
+}
+
+/**
+ * set_default_header_data
+ * @crypt_stat: The cryptographic context
+ *
+ * For version 0 file format; this function is only for backwards
+ * compatibility for files created with the prior versions of
+ * eCryptfs.
+ */
+static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
+}
+
+void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
+{
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	u64 file_size;
+
+	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
+	mount_crypt_stat =
+		&ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
+	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
+		file_size = i_size_read(ecryptfs_inode_to_lower(inode));
+		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+			file_size += crypt_stat->metadata_size;
+	} else
+		file_size = get_unaligned_be64(page_virt);
+	i_size_write(inode, (loff_t)file_size);
+	crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
+}
+
+/**
+ * ecryptfs_read_headers_virt
+ * @page_virt: The virtual address into which to read the headers
+ * @crypt_stat: The cryptographic context
+ * @ecryptfs_dentry: The eCryptfs dentry
+ * @validate_header_size: Whether to validate the header size while reading
+ *
+ * Read/parse the header data. The header format is detailed in the
+ * comment block for the ecryptfs_write_headers_virt() function.
+ *
+ * Returns zero on success
+ */
+static int ecryptfs_read_headers_virt(char *page_virt,
+				      struct ecryptfs_crypt_stat *crypt_stat,
+				      struct dentry *ecryptfs_dentry,
+				      int validate_header_size)
+{
+	int rc = 0;
+	int offset;
+	int bytes_read;
+
+	ecryptfs_set_default_sizes(crypt_stat);
+	crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
+		ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	offset = ECRYPTFS_FILE_SIZE_BYTES;
+	rc = ecryptfs_validate_marker(page_virt + offset);
+	if (rc)
+		goto out;
+	if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
+		ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
+	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
+	ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
+	if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
+		ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
+				"file version [%d] is supported by this "
+				"version of eCryptfs\n",
+				crypt_stat->file_version,
+				ECRYPTFS_SUPPORTED_FILE_VERSION);
+		rc = -EINVAL;
+		goto out;
+	}
+	offset += bytes_read;
+	if (crypt_stat->file_version >= 1) {
+		rc = parse_header_metadata(crypt_stat, (page_virt + offset),
+					   &bytes_read, validate_header_size);
+		if (rc) {
+			ecryptfs_printk(KERN_WARNING, "Error reading header "
+					"metadata; rc = [%d]\n", rc);
+		}
+		offset += bytes_read;
+	} else
+		set_default_header_data(crypt_stat);
+	rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
+				       ecryptfs_dentry);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_read_xattr_region
+ * @page_virt: The vitual address into which to read the xattr data
+ * @ecryptfs_inode: The eCryptfs inode
+ *
+ * Attempts to read the crypto metadata from the extended attribute
+ * region of the lower file.
+ *
+ * Returns zero on success; non-zero on error
+ */
+int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
+{
+	struct dentry *lower_dentry =
+		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
+	ssize_t size;
+	int rc = 0;
+
+	size = ecryptfs_getxattr_lower(lower_dentry,
+				       ecryptfs_inode_to_lower(ecryptfs_inode),
+				       ECRYPTFS_XATTR_NAME,
+				       page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
+	if (size < 0) {
+		if (unlikely(ecryptfs_verbosity > 0))
+			printk(KERN_INFO "Error attempting to read the [%s] "
+			       "xattr from the lower file; return value = "
+			       "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
+		rc = -EINVAL;
+		goto out;
+	}
+out:
+	return rc;
+}
+
+int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
+					    struct inode *inode)
+{
+	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
+	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
+	int rc;
+
+	rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
+				     ecryptfs_inode_to_lower(inode),
+				     ECRYPTFS_XATTR_NAME, file_size,
+				     ECRYPTFS_SIZE_AND_MARKER_BYTES);
+	if (rc < 0)
+		return rc;
+	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
+		return -EINVAL;
+	rc = ecryptfs_validate_marker(marker);
+	if (!rc)
+		ecryptfs_i_size_init(file_size, inode);
+	return rc;
+}
+
+/*
+ * ecryptfs_read_metadata
+ *
+ * Common entry point for reading file metadata. From here, we could
+ * retrieve the header information from the header region of the file,
+ * the xattr region of the file, or some other repository that is
+ * stored separately from the file itself. The current implementation
+ * supports retrieving the metadata information from the file contents
+ * and from the xattr region.
+ *
+ * Returns zero if valid headers found and parsed; non-zero otherwise
+ */
+int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
+{
+	int rc;
+	char *page_virt;
+	struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
+	struct ecryptfs_crypt_stat *crypt_stat =
+	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+		&ecryptfs_superblock_to_private(
+			ecryptfs_dentry->d_sb)->mount_crypt_stat;
+
+	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
+						      mount_crypt_stat);
+	/* Read the first page from the underlying file */
+	page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
+	if (!page_virt) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
+				 ecryptfs_inode);
+	if (rc >= 0)
+		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
+						ecryptfs_dentry,
+						ECRYPTFS_VALIDATE_HEADER_SIZE);
+	if (rc) {
+		/* metadata is not in the file header, so try xattrs */
+		memset(page_virt, 0, PAGE_SIZE);
+		rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
+		if (rc) {
+			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
+			       "file header region or xattr region, inode %lu\n",
+				ecryptfs_inode->i_ino);
+			rc = -EINVAL;
+			goto out;
+		}
+		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
+						ecryptfs_dentry,
+						ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
+		if (rc) {
+			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
+			       "file xattr region either, inode %lu\n",
+				ecryptfs_inode->i_ino);
+			rc = -EINVAL;
+		}
+		if (crypt_stat->mount_crypt_stat->flags
+		    & ECRYPTFS_XATTR_METADATA_ENABLED) {
+			crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
+		} else {
+			printk(KERN_WARNING "Attempt to access file with "
+			       "crypto metadata only in the extended attribute "
+			       "region, but eCryptfs was mounted without "
+			       "xattr support enabled. eCryptfs will not treat "
+			       "this like an encrypted file, inode %lu\n",
+				ecryptfs_inode->i_ino);
+			rc = -EINVAL;
+		}
+	}
+out:
+	if (page_virt) {
+		memset(page_virt, 0, PAGE_SIZE);
+		kmem_cache_free(ecryptfs_header_cache, page_virt);
+	}
+	return rc;
+}
+
+/*
+ * ecryptfs_encrypt_filename - encrypt filename
+ *
+ * CBC-encrypts the filename. We do not want to encrypt the same
+ * filename with the same key and IV, which may happen with hard
+ * links, so we prepend random bits to each filename.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int
+ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
+			  struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	int rc = 0;
+
+	filename->encrypted_filename = NULL;
+	filename->encrypted_filename_size = 0;
+	if (mount_crypt_stat && (mount_crypt_stat->flags
+				     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
+		size_t packet_size;
+		size_t remaining_bytes;
+
+		rc = ecryptfs_write_tag_70_packet(
+			NULL, NULL,
+			&filename->encrypted_filename_size,
+			mount_crypt_stat, NULL,
+			filename->filename_size);
+		if (rc) {
+			printk(KERN_ERR "%s: Error attempting to get packet "
+			       "size for tag 72; rc = [%d]\n", __func__,
+			       rc);
+			filename->encrypted_filename_size = 0;
+			goto out;
+		}
+		filename->encrypted_filename =
+			kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
+		if (!filename->encrypted_filename) {
+			rc = -ENOMEM;
+			goto out;
+		}
+		remaining_bytes = filename->encrypted_filename_size;
+		rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
+						  &remaining_bytes,
+						  &packet_size,
+						  mount_crypt_stat,
+						  filename->filename,
+						  filename->filename_size);
+		if (rc) {
+			printk(KERN_ERR "%s: Error attempting to generate "
+			       "tag 70 packet; rc = [%d]\n", __func__,
+			       rc);
+			kfree(filename->encrypted_filename);
+			filename->encrypted_filename = NULL;
+			filename->encrypted_filename_size = 0;
+			goto out;
+		}
+		filename->encrypted_filename_size = packet_size;
+	} else {
+		printk(KERN_ERR "%s: No support for requested filename "
+		       "encryption method in this release\n", __func__);
+		rc = -EOPNOTSUPP;
+		goto out;
+	}
+out:
+	return rc;
+}
+
+static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
+				  const char *name, size_t name_size)
+{
+	int rc = 0;
+
+	(*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
+	if (!(*copied_name)) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	memcpy((void *)(*copied_name), (void *)name, name_size);
+	(*copied_name)[(name_size)] = '\0';	/* Only for convenience
+						 * in printing out the
+						 * string in debug
+						 * messages */
+	(*copied_name_size) = name_size;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_process_key_cipher - Perform key cipher initialization.
+ * @key_tfm: Crypto context for key material, set by this function
+ * @cipher_name: Name of the cipher
+ * @key_size: Size of the key in bytes
+ *
+ * Returns zero on success. Any crypto_tfm structs allocated here
+ * should be released by other functions, such as on a superblock put
+ * event, regardless of whether this function succeeds for fails.
+ */
+static int
+ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
+			    char *cipher_name, size_t *key_size)
+{
+	char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
+	char *full_alg_name = NULL;
+	int rc;
+
+	*key_tfm = NULL;
+	if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
+		      "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
+		goto out;
+	}
+	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
+						    "ecb");
+	if (rc)
+		goto out;
+	*key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(*key_tfm)) {
+		rc = PTR_ERR(*key_tfm);
+		printk(KERN_ERR "Unable to allocate crypto cipher with name "
+		       "[%s]; rc = [%d]\n", full_alg_name, rc);
+		goto out;
+	}
+	crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
+	if (*key_size == 0)
+		*key_size = crypto_skcipher_max_keysize(*key_tfm);
+	get_random_bytes(dummy_key, *key_size);
+	rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to set key of size [%zd] for "
+		       "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
+		       rc);
+		rc = -EINVAL;
+		goto out;
+	}
+out:
+	kfree(full_alg_name);
+	return rc;
+}
+
+struct kmem_cache *ecryptfs_key_tfm_cache;
+static struct list_head key_tfm_list;
+DEFINE_MUTEX(key_tfm_list_mutex);
+
+int __init ecryptfs_init_crypto(void)
+{
+	INIT_LIST_HEAD(&key_tfm_list);
+	return 0;
+}
+
+/**
+ * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
+ *
+ * Called only at module unload time
+ */
+int ecryptfs_destroy_crypto(void)
+{
+	struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
+
+	mutex_lock(&key_tfm_list_mutex);
+	list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
+				 key_tfm_list) {
+		list_del(&key_tfm->key_tfm_list);
+		crypto_free_skcipher(key_tfm->key_tfm);
+		kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
+	}
+	mutex_unlock(&key_tfm_list_mutex);
+	return 0;
+}
+
+int
+ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
+			 size_t key_size)
+{
+	struct ecryptfs_key_tfm *tmp_tfm;
+	int rc = 0;
+
+	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
+
+	tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
+	if (key_tfm)
+		(*key_tfm) = tmp_tfm;
+	if (!tmp_tfm) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	mutex_init(&tmp_tfm->key_tfm_mutex);
+	strncpy(tmp_tfm->cipher_name, cipher_name,
+		ECRYPTFS_MAX_CIPHER_NAME_SIZE);
+	tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
+	tmp_tfm->key_size = key_size;
+	rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
+					 tmp_tfm->cipher_name,
+					 &tmp_tfm->key_size);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to initialize key TFM "
+		       "cipher with name = [%s]; rc = [%d]\n",
+		       tmp_tfm->cipher_name, rc);
+		kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
+		if (key_tfm)
+			(*key_tfm) = NULL;
+		goto out;
+	}
+	list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
+ * @cipher_name: the name of the cipher to search for
+ * @key_tfm: set to corresponding tfm if found
+ *
+ * Searches for cached key_tfm matching @cipher_name
+ * Must be called with &key_tfm_list_mutex held
+ * Returns 1 if found, with @key_tfm set
+ * Returns 0 if not found, with @key_tfm set to NULL
+ */
+int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
+{
+	struct ecryptfs_key_tfm *tmp_key_tfm;
+
+	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
+
+	list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
+		if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
+			if (key_tfm)
+				(*key_tfm) = tmp_key_tfm;
+			return 1;
+		}
+	}
+	if (key_tfm)
+		(*key_tfm) = NULL;
+	return 0;
+}
+
+/**
+ * ecryptfs_get_tfm_and_mutex_for_cipher_name
+ *
+ * @tfm: set to cached tfm found, or new tfm created
+ * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
+ * @cipher_name: the name of the cipher to search for and/or add
+ *
+ * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
+ * Searches for cached item first, and creates new if not found.
+ * Returns 0 on success, non-zero if adding new cipher failed
+ */
+int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
+					       struct mutex **tfm_mutex,
+					       char *cipher_name)
+{
+	struct ecryptfs_key_tfm *key_tfm;
+	int rc = 0;
+
+	(*tfm) = NULL;
+	(*tfm_mutex) = NULL;
+
+	mutex_lock(&key_tfm_list_mutex);
+	if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
+		rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
+		if (rc) {
+			printk(KERN_ERR "Error adding new key_tfm to list; "
+					"rc = [%d]\n", rc);
+			goto out;
+		}
+	}
+	(*tfm) = key_tfm->key_tfm;
+	(*tfm_mutex) = &key_tfm->key_tfm_mutex;
+out:
+	mutex_unlock(&key_tfm_list_mutex);
+	return rc;
+}
+
+/* 64 characters forming a 6-bit target field */
+static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
+						 "EFGHIJKLMNOPQRST"
+						 "UVWXYZabcdefghij"
+						 "klmnopqrstuvwxyz");
+
+/* We could either offset on every reverse map or just pad some 0x00's
+ * at the front here */
+static const unsigned char filename_rev_map[256] = {
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
+	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
+	0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
+	0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
+	0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
+	0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
+	0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
+	0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
+	0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
+	0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
+	0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
+};
+
+/**
+ * ecryptfs_encode_for_filename
+ * @dst: Destination location for encoded filename
+ * @dst_size: Size of the encoded filename in bytes
+ * @src: Source location for the filename to encode
+ * @src_size: Size of the source in bytes
+ */
+static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
+				  unsigned char *src, size_t src_size)
+{
+	size_t num_blocks;
+	size_t block_num = 0;
+	size_t dst_offset = 0;
+	unsigned char last_block[3];
+
+	if (src_size == 0) {
+		(*dst_size) = 0;
+		goto out;
+	}
+	num_blocks = (src_size / 3);
+	if ((src_size % 3) == 0) {
+		memcpy(last_block, (&src[src_size - 3]), 3);
+	} else {
+		num_blocks++;
+		last_block[2] = 0x00;
+		switch (src_size % 3) {
+		case 1:
+			last_block[0] = src[src_size - 1];
+			last_block[1] = 0x00;
+			break;
+		case 2:
+			last_block[0] = src[src_size - 2];
+			last_block[1] = src[src_size - 1];
+		}
+	}
+	(*dst_size) = (num_blocks * 4);
+	if (!dst)
+		goto out;
+	while (block_num < num_blocks) {
+		unsigned char *src_block;
+		unsigned char dst_block[4];
+
+		if (block_num == (num_blocks - 1))
+			src_block = last_block;
+		else
+			src_block = &src[block_num * 3];
+		dst_block[0] = ((src_block[0] >> 2) & 0x3F);
+		dst_block[1] = (((src_block[0] << 4) & 0x30)
+				| ((src_block[1] >> 4) & 0x0F));
+		dst_block[2] = (((src_block[1] << 2) & 0x3C)
+				| ((src_block[2] >> 6) & 0x03));
+		dst_block[3] = (src_block[2] & 0x3F);
+		dst[dst_offset++] = portable_filename_chars[dst_block[0]];
+		dst[dst_offset++] = portable_filename_chars[dst_block[1]];
+		dst[dst_offset++] = portable_filename_chars[dst_block[2]];
+		dst[dst_offset++] = portable_filename_chars[dst_block[3]];
+		block_num++;
+	}
+out:
+	return;
+}
+
+static size_t ecryptfs_max_decoded_size(size_t encoded_size)
+{
+	/* Not exact; conservatively long. Every block of 4
+	 * encoded characters decodes into a block of 3
+	 * decoded characters. This segment of code provides
+	 * the caller with the maximum amount of allocated
+	 * space that @dst will need to point to in a
+	 * subsequent call. */
+	return ((encoded_size + 1) * 3) / 4;
+}
+
+/**
+ * ecryptfs_decode_from_filename
+ * @dst: If NULL, this function only sets @dst_size and returns. If
+ *       non-NULL, this function decodes the encoded octets in @src
+ *       into the memory that @dst points to.
+ * @dst_size: Set to the size of the decoded string.
+ * @src: The encoded set of octets to decode.
+ * @src_size: The size of the encoded set of octets to decode.
+ */
+static void
+ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
+			      const unsigned char *src, size_t src_size)
+{
+	u8 current_bit_offset = 0;
+	size_t src_byte_offset = 0;
+	size_t dst_byte_offset = 0;
+
+	if (!dst) {
+		(*dst_size) = ecryptfs_max_decoded_size(src_size);
+		goto out;
+	}
+	while (src_byte_offset < src_size) {
+		unsigned char src_byte =
+				filename_rev_map[(int)src[src_byte_offset]];
+
+		switch (current_bit_offset) {
+		case 0:
+			dst[dst_byte_offset] = (src_byte << 2);
+			current_bit_offset = 6;
+			break;
+		case 6:
+			dst[dst_byte_offset++] |= (src_byte >> 4);
+			dst[dst_byte_offset] = ((src_byte & 0xF)
+						 << 4);
+			current_bit_offset = 4;
+			break;
+		case 4:
+			dst[dst_byte_offset++] |= (src_byte >> 2);
+			dst[dst_byte_offset] = (src_byte << 6);
+			current_bit_offset = 2;
+			break;
+		case 2:
+			dst[dst_byte_offset++] |= (src_byte);
+			current_bit_offset = 0;
+			break;
+		}
+		src_byte_offset++;
+	}
+	(*dst_size) = dst_byte_offset;
+out:
+	return;
+}
+
+/**
+ * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
+ * @encoded_name: The encrypted name
+ * @encoded_name_size: Length of the encrypted name
+ * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
+ * @name: The plaintext name
+ * @name_size: The length of the plaintext name
+ *
+ * Encrypts and encodes a filename into something that constitutes a
+ * valid filename for a filesystem, with printable characters.
+ *
+ * We assume that we have a properly initialized crypto context,
+ * pointed to by crypt_stat->tfm.
+ *
+ * Returns zero on success; non-zero on otherwise
+ */
+int ecryptfs_encrypt_and_encode_filename(
+	char **encoded_name,
+	size_t *encoded_name_size,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+	const char *name, size_t name_size)
+{
+	size_t encoded_name_no_prefix_size;
+	int rc = 0;
+
+	(*encoded_name) = NULL;
+	(*encoded_name_size) = 0;
+	if (mount_crypt_stat && (mount_crypt_stat->flags
+				     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+		struct ecryptfs_filename *filename;
+
+		filename = kzalloc(sizeof(*filename), GFP_KERNEL);
+		if (!filename) {
+			rc = -ENOMEM;
+			goto out;
+		}
+		filename->filename = (char *)name;
+		filename->filename_size = name_size;
+		rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
+		if (rc) {
+			printk(KERN_ERR "%s: Error attempting to encrypt "
+			       "filename; rc = [%d]\n", __func__, rc);
+			kfree(filename);
+			goto out;
+		}
+		ecryptfs_encode_for_filename(
+			NULL, &encoded_name_no_prefix_size,
+			filename->encrypted_filename,
+			filename->encrypted_filename_size);
+		if (mount_crypt_stat
+			&& (mount_crypt_stat->flags
+			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
+			(*encoded_name_size) =
+				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
+				 + encoded_name_no_prefix_size);
+		else
+			(*encoded_name_size) =
+				(ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
+				 + encoded_name_no_prefix_size);
+		(*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
+		if (!(*encoded_name)) {
+			rc = -ENOMEM;
+			kfree(filename->encrypted_filename);
+			kfree(filename);
+			goto out;
+		}
+		if (mount_crypt_stat
+			&& (mount_crypt_stat->flags
+			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
+			memcpy((*encoded_name),
+			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
+			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
+			ecryptfs_encode_for_filename(
+			    ((*encoded_name)
+			     + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
+			    &encoded_name_no_prefix_size,
+			    filename->encrypted_filename,
+			    filename->encrypted_filename_size);
+			(*encoded_name_size) =
+				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
+				 + encoded_name_no_prefix_size);
+			(*encoded_name)[(*encoded_name_size)] = '\0';
+		} else {
+			rc = -EOPNOTSUPP;
+		}
+		if (rc) {
+			printk(KERN_ERR "%s: Error attempting to encode "
+			       "encrypted filename; rc = [%d]\n", __func__,
+			       rc);
+			kfree((*encoded_name));
+			(*encoded_name) = NULL;
+			(*encoded_name_size) = 0;
+		}
+		kfree(filename->encrypted_filename);
+		kfree(filename);
+	} else {
+		rc = ecryptfs_copy_filename(encoded_name,
+					    encoded_name_size,
+					    name, name_size);
+	}
+out:
+	return rc;
+}
+
+static bool is_dot_dotdot(const char *name, size_t name_size)
+{
+	if (name_size == 1 && name[0] == '.')
+		return true;
+	else if (name_size == 2 && name[0] == '.' && name[1] == '.')
+		return true;
+
+	return false;
+}
+
+/**
+ * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
+ * @plaintext_name: The plaintext name
+ * @plaintext_name_size: The plaintext name size
+ * @sb: Ecryptfs's super_block
+ * @name: The filename in cipher text
+ * @name_size: The cipher text name size
+ *
+ * Decrypts and decodes the filename.
+ *
+ * Returns zero on error; non-zero otherwise
+ */
+int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
+					 size_t *plaintext_name_size,
+					 struct super_block *sb,
+					 const char *name, size_t name_size)
+{
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
+	char *decoded_name;
+	size_t decoded_name_size;
+	size_t packet_size;
+	int rc = 0;
+
+	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
+	    !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
+		if (is_dot_dotdot(name, name_size)) {
+			rc = ecryptfs_copy_filename(plaintext_name,
+						    plaintext_name_size,
+						    name, name_size);
+			goto out;
+		}
+
+		if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
+		    strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
+			    ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
+			rc = -EINVAL;
+			goto out;
+		}
+
+		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
+		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
+		ecryptfs_decode_from_filename(NULL, &decoded_name_size,
+					      name, name_size);
+		decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
+		if (!decoded_name) {
+			rc = -ENOMEM;
+			goto out;
+		}
+		ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
+					      name, name_size);
+		rc = ecryptfs_parse_tag_70_packet(plaintext_name,
+						  plaintext_name_size,
+						  &packet_size,
+						  mount_crypt_stat,
+						  decoded_name,
+						  decoded_name_size);
+		if (rc) {
+			ecryptfs_printk(KERN_DEBUG,
+					"%s: Could not parse tag 70 packet from filename\n",
+					__func__);
+			goto out_free;
+		}
+	} else {
+		rc = ecryptfs_copy_filename(plaintext_name,
+					    plaintext_name_size,
+					    name, name_size);
+		goto out;
+	}
+out_free:
+	kfree(decoded_name);
+out:
+	return rc;
+}
+
+#define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
+
+int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
+			   struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	struct crypto_skcipher *tfm;
+	struct mutex *tfm_mutex;
+	size_t cipher_blocksize;
+	int rc;
+
+	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+		(*namelen) = lower_namelen;
+		return 0;
+	}
+
+	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
+			mount_crypt_stat->global_default_fn_cipher_name);
+	if (unlikely(rc)) {
+		(*namelen) = 0;
+		return rc;
+	}
+
+	mutex_lock(tfm_mutex);
+	cipher_blocksize = crypto_skcipher_blocksize(tfm);
+	mutex_unlock(tfm_mutex);
+
+	/* Return an exact amount for the common cases */
+	if (lower_namelen == NAME_MAX
+	    && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
+		(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
+		return 0;
+	}
+
+	/* Return a safe estimate for the uncommon cases */
+	(*namelen) = lower_namelen;
+	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
+	/* Since this is the max decoded size, subtract 1 "decoded block" len */
+	(*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
+	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
+	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
+	/* Worst case is that the filename is padded nearly a full block size */
+	(*namelen) -= cipher_blocksize - 1;
+
+	if ((*namelen) < 0)
+		(*namelen) = 0;
+
+	return 0;
+}