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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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;
 }

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