crypto.c

Go to the documentation of this file.

#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/crypto.h>
#include <linux/file.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"

static int
ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                 struct page *dst_page, int dst_offset,
                 struct page *src_page, int src_offset, int size,
                 unsigned char *iv);
static int
ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                 struct page *dst_page, int dst_offset,
                 struct page *src_page, int src_offset, int size,
                 unsigned char *iv);

void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
{
    int x;

    for (x = 0; x < src_size; x++)
        sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
}

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);
    }
}

static int ecryptfs_calculate_md5(char *dst,
                  struct ecryptfs_crypt_stat *crypt_stat,
                  char *src, int len)
{
    struct scatterlist sg;
    struct hash_desc desc = {
        .tfm = crypt_stat->hash_tfm,
        .flags = CRYPTO_TFM_REQ_MAY_SLEEP
    };
    int rc = 0;

    mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
    sg_init_one(&sg, (u8 *)src, len);
    if (!desc.tfm) {
        desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
                         CRYPTO_ALG_ASYNC);
        if (IS_ERR(desc.tfm)) {
            rc = PTR_ERR(desc.tfm);
            ecryptfs_printk(KERN_ERR, "Error attempting to "
                    "allocate crypto context; rc = [%d]\n",
                    rc);
            goto out;
        }
        crypt_stat->hash_tfm = desc.tfm;
    }
    rc = crypto_hash_init(&desc);
    if (rc) {
        printk(KERN_ERR
               "%s: Error initializing crypto hash; rc = [%d]\n",
               __func__, rc);
        goto out;
    }
    rc = crypto_hash_update(&desc, &sg, len);
    if (rc) {
        printk(KERN_ERR
               "%s: Error updating crypto hash; rc = [%d]\n",
               __func__, rc);
        goto out;
    }
    rc = crypto_hash_final(&desc, dst);
    if (rc) {
        printk(KERN_ERR
               "%s: Error finalizing crypto hash; rc = [%d]\n",
               __func__, rc);
        goto out;
    }
out:
    mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
    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;
}

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;
}

void
ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
{
    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);
    mutex_init(&crypt_stat->cs_hash_tfm_mutex);
    crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
}

void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
{
    struct ecryptfs_key_sig *key_sig, *key_sig_tmp;

    if (crypt_stat->tfm)
        crypto_free_blkcipher(crypt_stat->tfm);
    if (crypt_stat->hash_tfm)
        crypto_free_hash(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->global_auth_tok_key
            && !(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));
}

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);
        if (sg)
            sg_set_page(&sg[i], pg, 0, offset);
        remainder_of_page = PAGE_CACHE_SIZE - offset;
        if (size >= remainder_of_page) {
            if (sg)
                sg[i].length = remainder_of_page;
            addr += remainder_of_page;
            size -= remainder_of_page;
        } else {
            if (sg)
                sg[i].length = size;
            addr += size;
            size = 0;
        }
        i++;
    }
    if (size > 0)
        return -ENOMEM;
    return i;
}

static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
                   struct scatterlist *dest_sg,
                   struct scatterlist *src_sg, int size,
                   unsigned char *iv)
{
    struct blkcipher_desc desc = {
        .tfm = crypt_stat->tfm,
        .info = iv,
        .flags = CRYPTO_TFM_REQ_MAY_SLEEP
    };
    int rc = 0;

    BUG_ON(!crypt_stat || !crypt_stat->tfm
           || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
    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);
    }
    /* Consider doing this once, when the file is opened */
    mutex_lock(&crypt_stat->cs_tfm_mutex);
    if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
        rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
                         crypt_stat->key_size);
        crypt_stat->flags |= ECRYPTFS_KEY_SET;
    }
    if (rc) {
        ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
                rc);
        mutex_unlock(&crypt_stat->cs_tfm_mutex);
        rc = -EINVAL;
        goto out;
    }
    ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
    crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
    mutex_unlock(&crypt_stat->cs_tfm_mutex);
out:
    return rc;
}

static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
                         struct ecryptfs_crypt_stat *crypt_stat)
{
    (*offset) = ecryptfs_lower_header_size(crypt_stat)
            + (crypt_stat->extent_size * extent_num);
}

static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
                   struct ecryptfs_crypt_stat *crypt_stat,
                   struct page *page,
                   unsigned long extent_offset)
{
    loff_t extent_base;
    char extent_iv[ECRYPTFS_MAX_IV_BYTES];
    int rc;

    extent_base = (((loff_t)page->index)
               * (PAGE_CACHE_SIZE / crypt_stat->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;
    }
    rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
                      page, (extent_offset
                         * crypt_stat->extent_size),
                      crypt_stat->extent_size, extent_iv);
    if (rc < 0) {
        printk(KERN_ERR "%s: Error attempting to encrypt page with "
               "page->index = [%ld], extent_offset = [%ld]; "
               "rc = [%d]\n", __func__, page->index, extent_offset,
               rc);
        goto out;
    }
    rc = 0;
out:
    return rc;
}

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;
    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;
    }
    enc_extent_virt = kmap(enc_extent_page);
    for (extent_offset = 0;
         extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
         extent_offset++) {
        loff_t offset;

        rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
                         extent_offset);
        if (rc) {
            printk(KERN_ERR "%s: Error encrypting extent; "
                   "rc = [%d]\n", __func__, rc);
            goto out;
        }
        ecryptfs_lower_offset_for_extent(
            &offset, ((((loff_t)page->index)
                   * (PAGE_CACHE_SIZE
                      / crypt_stat->extent_size))
                  + extent_offset), crypt_stat);
        rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
                      offset, crypt_stat->extent_size);
        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) {
        kunmap(enc_extent_page);
        __free_page(enc_extent_page);
    }
    return rc;
}

static int ecryptfs_decrypt_extent(struct page *page,
                   struct ecryptfs_crypt_stat *crypt_stat,
                   struct page *enc_extent_page,
                   unsigned long extent_offset)
{
    loff_t extent_base;
    char extent_iv[ECRYPTFS_MAX_IV_BYTES];
    int rc;

    extent_base = (((loff_t)page->index)
               * (PAGE_CACHE_SIZE / crypt_stat->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;
    }
    rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
                      (extent_offset
                       * crypt_stat->extent_size),
                      enc_extent_page, 0,
                      crypt_stat->extent_size, extent_iv);
    if (rc < 0) {
        printk(KERN_ERR "%s: Error attempting to decrypt to page with "
               "page->index = [%ld], extent_offset = [%ld]; "
               "rc = [%d]\n", __func__, page->index, extent_offset,
               rc);
        goto out;
    }
    rc = 0;
out:
    return rc;
}

int ecryptfs_decrypt_page(struct page *page)
{
    struct inode *ecryptfs_inode;
    struct ecryptfs_crypt_stat *crypt_stat;
    char *enc_extent_virt;
    struct page *enc_extent_page = NULL;
    unsigned long extent_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;
    }
    enc_extent_virt = kmap(enc_extent_page);
    for (extent_offset = 0;
         extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
         extent_offset++) {
        loff_t offset;

        ecryptfs_lower_offset_for_extent(
            &offset, ((page->index * (PAGE_CACHE_SIZE
                          / crypt_stat->extent_size))
                  + extent_offset), crypt_stat);
        rc = ecryptfs_read_lower(enc_extent_virt, offset,
                     crypt_stat->extent_size,
                     ecryptfs_inode);
        if (rc < 0) {
            ecryptfs_printk(KERN_ERR, "Error attempting "
                    "to read lower page; rc = [%d]"
                    "\n", rc);
            goto out;
        }
        rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
                         extent_offset);
        if (rc) {
            printk(KERN_ERR "%s: Error encrypting extent; "
                   "rc = [%d]\n", __func__, rc);
            goto out;
        }
    }
out:
    if (enc_extent_page) {
        kunmap(enc_extent_page);
        __free_page(enc_extent_page);
    }
    return rc;
}

static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
                   struct scatterlist *dest_sg,
                   struct scatterlist *src_sg, int size,
                   unsigned char *iv)
{
    struct blkcipher_desc desc = {
        .tfm = crypt_stat->tfm,
        .info = iv,
        .flags = CRYPTO_TFM_REQ_MAY_SLEEP
    };
    int rc = 0;

    /* Consider doing this once, when the file is opened */
    mutex_lock(&crypt_stat->cs_tfm_mutex);
    rc = crypto_blkcipher_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;
    }
    ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
    rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
    mutex_unlock(&crypt_stat->cs_tfm_mutex);
    if (rc) {
        ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
                rc);
        goto out;
    }
    rc = size;
out:
    return rc;
}

static int
ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                 struct page *dst_page, int dst_offset,
                 struct page *src_page, int src_offset, int size,
                 unsigned char *iv)
{
    struct scatterlist src_sg, dst_sg;

    sg_init_table(&src_sg, 1);
    sg_init_table(&dst_sg, 1);

    sg_set_page(&src_sg, src_page, size, src_offset);
    sg_set_page(&dst_sg, dst_page, size, dst_offset);
    return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
}

static int
ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                 struct page *dst_page, int dst_offset,
                 struct page *src_page, int src_offset, int size,
                 unsigned char *iv)
{
    struct scatterlist src_sg, dst_sg;

    sg_init_table(&src_sg, 1);
    sg_set_page(&src_sg, src_page, size, src_offset);

    sg_init_table(&dst_sg, 1);
    sg_set_page(&dst_sg, dst_page, size, dst_offset);

    return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
}

#define ECRYPTFS_MAX_SCATTERLIST_LEN 4

int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
{
    char *full_alg_name;
    int rc = -EINVAL;

    if (!crypt_stat->cipher) {
        ecryptfs_printk(KERN_ERR, "No cipher specified\n");
        goto out;
    }
    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);
    if (crypt_stat->tfm) {
        rc = 0;
        goto out;
    }
    mutex_lock(&crypt_stat->cs_tfm_mutex);
    rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
                            crypt_stat->cipher, "cbc");
    if (rc)
        goto out_unlock;
    crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
                         CRYPTO_ALG_ASYNC);
    kfree(full_alg_name);
    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",
                crypt_stat->cipher);
        goto out_unlock;
    }
    crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
    rc = 0;
out_unlock:
    mutex_unlock(&crypt_stat->cs_tfm_mutex);
out:
    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_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
            crypt_stat->metadata_size =
                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
        else
            crypt_stat->metadata_size = PAGE_CACHE_SIZE;
    }
}

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);
    }
}

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;
}

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;
}

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;
}

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}
};

static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
                  char *page_virt, int *bytes_read)
{
    int rc = 0;
    int i;
    u32 flags;

    flags = get_unaligned_be32(page_virt);
    for (i = 0; i < ((sizeof(ecryptfs_flag_map)
              / sizeof(struct ecryptfs_flag_map_elem))); 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;
    return rc;
}

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 < ((sizeof(ecryptfs_flag_map)
              / sizeof(struct ecryptfs_flag_map_elem))); 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 applicatoins 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}
};

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;
}

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 < ECRYPTFS_SIZE_AND_MARKER_BYTES)
        return rc >= 0 ? -EINVAL : rc;
    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;

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,
                 char *page_virt, size_t size)
{
    int rc;

    rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
                   size, 0);
    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;
}

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, 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;
}

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;
}

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, ecryptfs_dentry->d_inode);
    offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
    rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
                    &bytes_read);
    if (rc) {
        ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
        goto out;
    }
    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;
}

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_dentry;
    ssize_t size;
    int rc = 0;

    size = ecryptfs_getxattr_lower(lower_dentry, 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_XATTR_NAME, file_size,
                     ECRYPTFS_SIZE_AND_MARKER_BYTES);
    if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
        return rc >= 0 ? -EINVAL : rc;
    rc = ecryptfs_validate_marker(marker);
    if (!rc)
        ecryptfs_i_size_init(file_size, inode);
    return rc;
}

int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
{
    int rc;
    char *page_virt;
    struct inode *ecryptfs_inode = ecryptfs_dentry->d_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_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;
        printk(KERN_ERR "%s: Unable to allocate page_virt\n",
               __func__);
        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_CACHE_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_CACHE_SIZE);
        kmem_cache_free(ecryptfs_header_cache, page_virt);
    }
    return rc;
}

static int
ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
              struct ecryptfs_crypt_stat *crypt_stat,
              struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
    int rc = 0;

    filename->encrypted_filename = NULL;
    filename->encrypted_filename_size = 0;
    if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
        || (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) {
            printk(KERN_ERR "%s: Out of memory whilst attempting "
                   "to kmalloc [%zd] bytes\n", __func__,
                   filename->encrypted_filename_size);
            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;
}

static int
ecryptfs_process_key_cipher(struct crypto_blkcipher **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_blkcipher(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_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
    if (*key_size == 0) {
        struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);

        *key_size = alg->max_keysize;
    }
    get_random_bytes(dummy_key, *key_size);
    rc = crypto_blkcipher_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;
struct mutex key_tfm_list_mutex;

int __init ecryptfs_init_crypto(void)
{
    mutex_init(&key_tfm_list_mutex);
    INIT_LIST_HEAD(&key_tfm_list);
    return 0;
}

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);
        if (key_tfm->key_tfm)
            crypto_free_blkcipher(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 != NULL)
        (*key_tfm) = tmp_tfm;
    if (!tmp_tfm) {
        rc = -ENOMEM;
        printk(KERN_ERR "Error attempting to allocate from "
               "ecryptfs_key_tfm_cache\n");
        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 != NULL)
            (*key_tfm) = NULL;
        goto out;
    }
    list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
out:
    return rc;
}

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;
}

int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **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 */
};

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;
}

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 == NULL) {
        (*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);
            dst[dst_byte_offset] = 0;
            current_bit_offset = 0;
            break;
        }
        src_byte_offset++;
    }
    (*dst_size) = dst_byte_offset;
out:
    return;
}

int ecryptfs_encrypt_and_encode_filename(
    char **encoded_name,
    size_t *encoded_name_size,
    struct ecryptfs_crypt_stat *crypt_stat,
    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 ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
        || (mount_crypt_stat && (mount_crypt_stat->flags
                     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
        struct ecryptfs_filename *filename;

        filename = kzalloc(sizeof(*filename), GFP_KERNEL);
        if (!filename) {
            printk(KERN_ERR "%s: Out of memory whilst attempting "
                   "to kzalloc [%zd] bytes\n", __func__,
                   sizeof(*filename));
            rc = -ENOMEM;
            goto out;
        }
        filename->filename = (char *)name;
        filename->filename_size = name_size;
        rc = ecryptfs_encrypt_filename(filename, crypt_stat,
                           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 ((crypt_stat && (crypt_stat->flags
                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
            || (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)) {
            printk(KERN_ERR "%s: Out of memory whilst attempting "
                   "to kzalloc [%zd] bytes\n", __func__,
                   (*encoded_name_size));
            rc = -ENOMEM;
            kfree(filename->encrypted_filename);
            kfree(filename);
            goto out;
        }
        if ((crypt_stat && (crypt_stat->flags
                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
            || (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;
}

int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
                     size_t *plaintext_name_size,
                     struct dentry *ecryptfs_dir_dentry,
                     const char *name, size_t name_size)
{
    struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
        &ecryptfs_superblock_to_private(
            ecryptfs_dir_dentry->d_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)
        && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
        && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
            ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
        const char *orig_name = name;
        size_t orig_name_size = name_size;

        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) {
            printk(KERN_ERR "%s: Out of memory whilst attempting "
                   "to kmalloc [%zd] bytes\n", __func__,
                   decoded_name_size);
            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) {
            printk(KERN_INFO "%s: Could not parse tag 70 packet "
                   "from filename; copying through filename "
                   "as-is\n", __func__);
            rc = ecryptfs_copy_filename(plaintext_name,
                            plaintext_name_size,
                            orig_name, orig_name_size);
            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 blkcipher_desc desc;
    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(&desc.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_blkcipher_blocksize(desc.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;
}