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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 <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);
/**
* 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.
*/
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);
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);
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) = ecryptfs_lower_header_size(crypt_stat)
+ (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);
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%.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);
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;
}
/**
* 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: Uninitialized crypt stats structure
*
* Initialize the crypto context.
*
* TODO: Performance: Keep a cache of initialized cipher contexts;
* only init if needed
*/
int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
{
char *full_alg_name;
int rc = -EINVAL;
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);
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;
}
}
/**
* 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;
if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
else if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
}
}
static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
struct ecryptfs_global_auth_tok *global_auth_tok;
int rc = 0;
mutex_lock(&crypt_stat->keysig_list_mutex);
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_for_each_entry(global_auth_tok,
&mount_crypt_stat->global_auth_tok_list,
mount_crypt_stat_list) {
if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
continue;
rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
if (rc) {
printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
goto out;
}
}
out:
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
mutex_unlock(&crypt_stat->keysig_list_mutex);
return rc;
}
/**
* ecryptfs_set_default_crypt_stat_vals
* @crypt_stat: The inode's cryptographic context
* @mount_crypt_stat: The mount point's cryptographic context
*
* Default values in the event that policy does not override them.
*/
static void ecryptfs_set_default_crypt_stat_vals(
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
mount_crypt_stat);
ecryptfs_set_default_sizes(crypt_stat);
strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
crypt_stat->mount_crypt_stat = mount_crypt_stat;
}
/**
* ecryptfs_new_file_context
* @ecryptfs_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);