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linux-sg2042/fs/ecryptfs/crypto.c

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/**
* 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>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#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 <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);
/**
* ecryptfs_to_hex
* @dst: Buffer to take hex character representation of contents of
* src; must be at least of size (src_size * 2)
* @src: Buffer to be converted to a hex string respresentation
* @src_size: number of bytes to convert
*/
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]);
}
/**
* 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 respresentation 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)
{
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;
}
/**
* 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.
*/
static 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.
*/
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;
}
/**
* 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;
if (crypt_stat->tfm)
crypto_free_blkcipher(crypt_stat->tfm);
if (crypt_stat->hash_tfm)
crypto_free_hash(crypt_stat->hash_tfm);
mutex_lock(&crypt_stat->keysig_list_mutex);
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);
}
mutex_unlock(&crypt_stat->keysig_list_mutex);
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);
mount_crypt_stat->num_global_auth_toks--;
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));
}
/**
* 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);
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;
}
/**
* encrypt_scatterlist
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
* @dest_sg: Destination of encrypted data
* @src_sg: Data to be encrypted
* @size: Length of data to be encrypted
* @iv: iv to use during encryption
*
* Returns the number of bytes encrypted; negative value on error
*/
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 [%d]; 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;
}
/**
* ecryptfs_lower_offset_for_extent
*
* Convert an eCryptfs page index into a lower byte offset
*/
static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
struct ecryptfs_crypt_stat *crypt_stat)
{
(*offset) = (crypt_stat->num_header_bytes_at_front
+ (crypt_stat->extent_size * extent_num));
}
/**
* ecryptfs_encrypt_extent
* @enc_extent_page: Allocated page into which to encrypt the data in
* @page
* @crypt_stat: crypt_stat containing cryptographic context for the
* encryption operation
* @page: Page containing plaintext data extent to encrypt
* @extent_offset: Page extent offset for use in generating IV
*
* Encrypts one extent of data.
*
* Return zero on success; non-zero otherwise
*/
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%.16x]; "
"rc = [%d]\n", (extent_base + extent_offset),
rc);
goto out;
}
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
"with iv:\n");
ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
"encryption:\n");
ecryptfs_dump_hex((char *)
(page_address(page)
+ (extent_offset * crypt_stat->extent_size)),
8);
}
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;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
"rc = [%d]\n", (extent_base + extent_offset),
rc);
ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
"encryption:\n");
ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
}
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;
int rc = 0;
ecryptfs_inode = page->mapping->host;
crypt_stat =
&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page,
0, PAGE_CACHE_SIZE);
if (rc)
printk(KERN_ERR "%s: Error attempting to copy "
"page at index [%ld]\n", __func__,
page->index);
goto out;
}
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) {
ecryptfs_printk(KERN_ERR, "Error attempting "
"to write lower page; rc = [%d]"
"\n", rc);
goto out;
}
}
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%.16x]; "
"rc = [%d]\n", (extent_base + extent_offset),
rc);
goto out;
}
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
"with iv:\n");
ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
"decryption:\n");
ecryptfs_dump_hex((char *)
(page_address(enc_extent_page)
+ (extent_offset * crypt_stat->extent_size)),
8);
}
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;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16x]; "
"rc = [%d]\n", (extent_base + extent_offset),
rc);
ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
"decryption:\n");
ecryptfs_dump_hex((char *)(page_address(page)
+ (extent_offset
* crypt_stat->extent_size)), 8);
}
out:
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 *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);
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
PAGE_CACHE_SIZE,
ecryptfs_inode);
if (rc)
printk(KERN_ERR "%s: Error attempting to copy "
"page at index [%ld]\n", __func__,
page->index);
goto out;
}
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) {
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;
}
/**
* decrypt_scatterlist
* @crypt_stat: Cryptographic context
* @dest_sg: The destination scatterlist to decrypt into
* @src_sg: The source scatterlist to decrypt from
* @size: The number of bytes to decrypt
* @iv: The initialization vector to use for the decryption
*
* Returns the number of bytes decrypted; negative value on error
*/
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;
}
/**
* ecryptfs_encrypt_page_offset
* @crypt_stat: The cryptographic context
* @dst_page: The page to encrypt into
* @dst_offset: The offset in the page to encrypt into
* @src_page: The page to encrypt from
* @src_offset: The offset in the page to encrypt from
* @size: The number of bytes to encrypt
* @iv: The initialization vector to use for the encryption
*
* Returns the number of bytes encrypted
*/
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);
}
/**
* ecryptfs_decrypt_page_offset
* @crypt_stat: The cryptographic context
* @dst_page: The page to decrypt into
* @dst_offset: The offset in the page to decrypt into
* @src_page: The page to decrypt from
* @src_offset: The offset in the page to decrypt from
* @size: The number of bytes to decrypt
* @iv: The initialization vector to use for the decryption
*
* Returns the number of bytes decrypted
*/
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
/**
* ecryptfs_init_crypt_ctx
* @crypt_stat: Uninitilized 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;
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 = [%d]\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);
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->num_header_bytes_at_front = 0;
else {
if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
crypt_stat->num_header_bytes_at_front =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
else
crypt_stat->num_header_bytes_at_front = PAGE_CACHE_SIZE;
}
}
/**
* ecryptfs_compute_root_iv
* @crypt_stats
*
* 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;
}
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(&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) {
rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
if (rc) {
printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
mutex_unlock(
&mount_crypt_stat->global_auth_tok_list_mutex);
goto out;
}
}
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
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_dentry: The eCryptfs dentry
*
* 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 dentry *ecryptfs_dentry)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
&ecryptfs_superblock_to_private(
ecryptfs_dentry->d_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;
}
/**
* contains_ecryptfs_marker - check for the ecryptfs marker
* @data: The data block in which to check
*
* Returns one if marker found; zero if not found
*/
static int contains_ecryptfs_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 1;
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 0;
}
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}
};
/**
* ecryptfs_process_flags
* @crypt_stat: The cryptographic context
* @page_virt: Source data to be parsed
* @bytes_read: Updated with the number of bytes read
*
* Returns zero on success; non-zero if the flag set is invalid
*/
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;
}
/**
* 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;
}
static void
write_ecryptfs_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}
};
/**
* ecryptfs_code_for_cipher_string
* @crypt_stat: The cryptographic context
*
* Returns zero on no match, or the cipher code on match
*/
u8 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
{
int i;
u8 code = 0;
struct ecryptfs_cipher_code_str_map_elem *map =
ecryptfs_cipher_code_str_map;
if (strcmp(crypt_stat->cipher, "aes") == 0) {
switch (crypt_stat->key_size) {
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(crypt_stat->cipher, 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(char *data,
struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat =
&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
int rc;
rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
ecryptfs_inode);
if (rc) {
printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
__func__, rc);
goto out;
}
if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
rc = -EINVAL;
ecryptfs_printk(KERN_DEBUG, "Valid marker not found\n");
}
out:
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->num_header_bytes_at_front
/ 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_1;
struct kmem_cache *ecryptfs_header_cache_2;
/**
* 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;
write_ecryptfs_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 ecryptfs_crypt_stat *crypt_stat,
struct dentry *ecryptfs_dentry,
char *virt)
{
int rc;
rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
0, crypt_stat->num_header_bytes_at_front);
if (rc)
printk(KERN_ERR "%s: Error attempting to write header "
"information to lower file; rc = [%d]\n", __func__,
rc);
return rc;
}
static int
ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
struct ecryptfs_crypt_stat *crypt_stat,
char *page_virt, size_t size)
{
int rc;
rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
size, 0);
return rc;
}
/**
* ecryptfs_write_metadata
* @ecryptfs_dentry: The eCryptfs dentry
*
* 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 ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
char *virt;
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;
}
/* Released in this function */
virt = (char *)get_zeroed_page(GFP_KERNEL);
if (!virt) {
printk(KERN_ERR "%s: Out of memory\n", __func__);
rc = -ENOMEM;
goto out;
}
rc = ecryptfs_write_headers_virt(virt, PAGE_CACHE_SIZE, &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,
crypt_stat, virt, size);
else
rc = ecryptfs_write_metadata_to_contents(crypt_stat,
ecryptfs_dentry, virt);
if (rc) {
printk(KERN_ERR "%s: Error writing metadata out to lower file; "
"rc = [%d]\n", __func__, rc);
goto out_free;
}
out_free:
free_page((unsigned long)virt);
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->num_header_bytes_at_front =
(((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->num_header_bytes_at_front
< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
rc = -EINVAL;
printk(KERN_WARNING "Invalid header size: [%zd]\n",
crypt_stat->num_header_bytes_at_front);
}
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->num_header_bytes_at_front =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
}
/**
* 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 = contains_ecryptfs_marker(page_virt + offset);
if (rc == 0) {
rc = -EINVAL;
goto out;
}
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;
}
/**
* 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_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(char *page_virt,
struct dentry *ecryptfs_dentry)
{
int rc;
rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
if (rc)
goto out;
if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
printk(KERN_WARNING "Valid data found in [%s] xattr, but "
"the marker is invalid\n", ECRYPTFS_XATTR_NAME);
rc = -EINVAL;
}
out:
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 repostory 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 = 0;
char *page_virt = NULL;
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_1, 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)
rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
ecryptfs_dentry,
ECRYPTFS_VALIDATE_HEADER_SIZE);
if (rc) {
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\n");
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\n");
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.\n");
rc = -EINVAL;
}
}
out:
if (page_virt) {
memset(page_virt, 0, PAGE_CACHE_SIZE);
kmem_cache_free(ecryptfs_header_cache_1, page_virt);
}
return rc;
}
/**
* ecryptfs_encode_filename - converts a plaintext file name to cipher text
* @crypt_stat: The crypt_stat struct associated with the file anem to encode
* @name: The plaintext name
* @length: The length of the plaintext
* @encoded_name: The encypted 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.
*
* TODO: Implement filename decoding and decryption here, in place of
* memcpy. We are keeping the framework around for now to (1)
* facilitate testing of the components needed to implement filename
* encryption and (2) to provide a code base from which other
* developers in the community can easily implement this feature.
*
* Returns the length of encoded filename; negative if error
*/
int
ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
const char *name, int length, char **encoded_name)
{
int error = 0;
(*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
if (!(*encoded_name)) {
error = -ENOMEM;
goto out;
}
/* TODO: Filename encryption is a scheduled feature for a
* future version of eCryptfs. This function is here only for
* the purpose of providing a framework for other developers
* to easily implement filename encryption. Hint: Replace this
* memcpy() with a call to encrypt and encode the
* filename, the set the length accordingly. */
memcpy((void *)(*encoded_name), (void *)name, length);
(*encoded_name)[length] = '\0';
error = length + 1;
out:
return error;
}
/**
* ecryptfs_decode_filename - converts the cipher text name to plaintext
* @crypt_stat: The crypt_stat struct associated with the file
* @name: The filename in cipher text
* @length: The length of the cipher text name
* @decrypted_name: The plaintext name
*
* Decodes and decrypts the filename.
*
* We assume that we have a properly initialized crypto context,
* pointed to by crypt_stat->tfm.
*
* TODO: Implement filename decoding and decryption here, in place of
* memcpy. We are keeping the framework around for now to (1)
* facilitate testing of the components needed to implement filename
* encryption and (2) to provide a code base from which other
* developers in the community can easily implement this feature.
*
* Returns the length of decoded filename; negative if error
*/
int
ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
const char *name, int length, char **decrypted_name)
{
int error = 0;
(*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
if (!(*decrypted_name)) {
error = -ENOMEM;
goto out;
}
/* TODO: Filename encryption is a scheduled feature for a
* future version of eCryptfs. This function is here only for
* the purpose of providing a framework for other developers
* to easily implement filename encryption. Hint: Replace this
* memcpy() with a call to decode and decrypt the
* filename, the set the length accordingly. */
memcpy((void *)(*decrypted_name), (void *)name, length);
(*decrypted_name)[length + 1] = '\0'; /* Only for convenience
* in printing out the
* string in debug
* messages */
error = length;
out:
return error;
}
/**
* 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_blkcipher **key_tfm,
char *cipher_name, size_t *key_size)
{
char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
char *full_alg_name;
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);
kfree(full_alg_name);
if (IS_ERR(*key_tfm)) {
rc = PTR_ERR(*key_tfm);
printk(KERN_ERR "Unable to allocate crypto cipher with name "
"[%s]; rc = [%d]\n", cipher_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, cipher_name, rc);
rc = -EINVAL;
goto out;
}
out:
return rc;
}
struct kmem_cache *ecryptfs_key_tfm_cache;
static struct list_head key_tfm_list;
struct mutex key_tfm_list_mutex;
int ecryptfs_init_crypto(void)
{
mutex_init(&key_tfm_list_mutex);
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);
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;
}
/**
* 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_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;
}
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