blob: dfa3ec9e5262ca880cdbcc550ea3021c4744dfe3 [file] [log] [blame]
/*
* Copyright (c) 2015-2018, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* 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.
*/
/*
* Per-File-Key (PFK).
*
* This driver is responsible for overall management of various
* Per File Encryption variants that work on top of or as part of different
* file systems.
*
* The driver has the following purpose :
* 1) Define priorities between PFE's if more than one is enabled
* 2) Extract key information from inode
* 3) Load and manage various keys in ICE HW engine
* 4) It should be invoked from various layers in FS/BLOCK/STORAGE DRIVER
* that need to take decision on HW encryption management of the data
* Some examples:
* BLOCK LAYER: when it takes decision on whether 2 chunks can be united
* to one encryption / decryption request sent to the HW
*
* UFS DRIVER: when it need to configure ICE HW with a particular key slot
* to be used for encryption / decryption
*
* PFE variants can differ on particular way of storing the cryptographic info
* inside inode, actions to be taken upon file operations, etc., but the common
* properties are described above
*
*/
/* Uncomment the line below to enable debug messages */
/* #define DEBUG 1 */
#define pr_fmt(fmt) "pfk [%s]: " fmt, __func__
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/printk.h>
#include <linux/bio.h>
#include <linux/security.h>
#include <crypto/algapi.h>
#include <crypto/ice.h>
#include <linux/pfk.h>
#include "pfk_kc.h"
#include "objsec.h"
#include "pfk_ice.h"
#include "pfk_ext4.h"
#include "pfk_f2fs.h"
#include "pfk_internal.h"
static bool pfk_ready;
/* might be replaced by a table when more than one cipher is supported */
#define PFK_SUPPORTED_KEY_SIZE 32
#define PFK_SUPPORTED_SALT_SIZE 32
/* Various PFE types and function tables to support each one of them */
enum pfe_type {EXT4_CRYPT_PFE, F2FS_CRYPT_PFE, INVALID_PFE};
typedef int (*pfk_parse_inode_type)(const struct bio *bio,
const struct inode *inode,
struct pfk_key_info *key_info,
enum ice_cryto_algo_mode *algo,
bool *is_pfe);
typedef bool (*pfk_allow_merge_bio_type)(const struct bio *bio1,
const struct bio *bio2, const struct inode *inode1,
const struct inode *inode2, unsigned int sectors);
static const pfk_parse_inode_type pfk_parse_inode_ftable[] = {
/* EXT4_CRYPT_PFE */ &pfk_ext4_parse_inode,
/* F2FS_CRYPT_PFE */ &pfk_f2fs_parse_inode,
};
static const pfk_allow_merge_bio_type pfk_allow_merge_bio_ftable[] = {
/* EXT4_CRYPT_PFE */ &pfk_ext4_allow_merge_bio,
/* F2FS_CRYPT_PFE */ &pfk_f2fs_allow_merge_bio,
};
static void __exit pfk_exit(void)
{
pfk_ready = false;
pfk_ext4_deinit();
pfk_f2fs_deinit();
pfk_kc_deinit();
}
static int __init pfk_init(void)
{
int ret = 0;
ret = pfk_ext4_init();
if (ret != 0)
goto fail;
ret = pfk_f2fs_init();
if (ret != 0)
goto fail;
ret = pfk_kc_init();
if (ret != 0) {
pr_err("could init pfk key cache, error %d\n", ret);
pfk_ext4_deinit();
pfk_f2fs_deinit();
goto fail;
}
pfk_ready = true;
pr_info("Driver initialized successfully\n");
return 0;
fail:
pr_err("Failed to init driver\n");
return -ENODEV;
}
/*
* If more than one type is supported simultaneously, this function will also
* set the priority between them
*/
static enum pfe_type pfk_get_pfe_type(const struct inode *inode)
{
if (!inode)
return INVALID_PFE;
if (pfk_is_ext4_type(inode))
return EXT4_CRYPT_PFE;
if (pfk_is_f2fs_type(inode))
return F2FS_CRYPT_PFE;
return INVALID_PFE;
}
/**
* inode_to_filename() - get the filename from inode pointer.
* @inode: inode pointer
*
* it is used for debug prints.
*
* Return: filename string or "unknown".
*/
char *inode_to_filename(const struct inode *inode)
{
struct dentry *dentry = NULL;
char *filename = NULL;
if (!inode)
return "NULL";
if (hlist_empty(&inode->i_dentry))
return "unknown";
dentry = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
filename = dentry->d_iname;
return filename;
}
/**
* pfk_is_ready() - driver is initialized and ready.
*
* Return: true if the driver is ready.
*/
static inline bool pfk_is_ready(void)
{
return pfk_ready;
}
/**
* pfk_bio_get_inode() - get the inode from a bio.
* @bio: Pointer to BIO structure.
*
* Walk the bio struct links to get the inode.
* Please note, that in general bio may consist of several pages from
* several files, but in our case we always assume that all pages come
* from the same file, since our logic ensures it. That is why we only
* walk through the first page to look for inode.
*
* Return: pointer to the inode struct if successful, or NULL otherwise.
*
*/
static struct inode *pfk_bio_get_inode(const struct bio *bio)
{
struct inode *inode;
if (!bio)
return NULL;
if (!bio_has_data((struct bio *)bio))
return NULL;
if (!bio->bi_io_vec)
return NULL;
if (!bio->bi_io_vec->bv_page)
return NULL;
/* Using direct-io (O_DIRECT) without page cache */
inode = dio_bio_get_inode((struct bio *)bio);
if (inode) {
pr_debug("inode on direct-io, inode = 0x%pK.\n", inode);
return inode;
}
if (!page_mapping(bio->bi_io_vec->bv_page))
return NULL;
return page_mapping(bio->bi_io_vec->bv_page)->host;
}
/**
* pfk_key_size_to_key_type() - translate key size to key size enum
* @key_size: key size in bytes
* @key_size_type: pointer to store the output enum (can be null)
*
* return 0 in case of success, error otherwise (i.e not supported key size)
*/
int pfk_key_size_to_key_type(size_t key_size,
enum ice_crpto_key_size *key_size_type)
{
/*
* currently only 32 bit key size is supported
* in the future, table with supported key sizes might
* be introduced
*/
if (key_size != PFK_SUPPORTED_KEY_SIZE) {
pr_err("not supported key size %zu\n", key_size);
return -EINVAL;
}
if (key_size_type)
*key_size_type = ICE_CRYPTO_KEY_SIZE_256;
return 0;
}
/*
* Retrieves filesystem type from inode's superblock
*/
bool pfe_is_inode_filesystem_type(const struct inode *inode,
const char *fs_type)
{
if (!inode || !fs_type)
return false;
if (!inode->i_sb)
return false;
if (!inode->i_sb->s_type)
return false;
return (strcmp(inode->i_sb->s_type->name, fs_type) == 0);
}
/**
* pfk_get_key_for_bio() - get the encryption key to be used for a bio
*
* @bio: pointer to the BIO
* @key_info: pointer to the key information which will be filled in
* @algo_mode: optional pointer to the algorithm identifier which will be set
* @is_pfe: will be set to false if the BIO should be left unencrypted
*
* Return: 0 if a key is being used, otherwise a -errno value
*/
static int pfk_get_key_for_bio(const struct bio *bio,
struct pfk_key_info *key_info,
enum ice_cryto_algo_mode *algo_mode,
bool *is_pfe, unsigned int *data_unit)
{
const struct inode *inode;
enum pfe_type which_pfe;
const struct blk_encryption_key *key = NULL;
char *s_type = NULL;
inode = pfk_bio_get_inode(bio);
which_pfe = pfk_get_pfe_type(inode);
s_type = (char *)pfk_kc_get_storage_type();
/*
* Update dun based on storage type.
* 512 byte dun - For ext4 emmc
* 4K dun - For ext4 ufs, f2fs ufs and f2fs emmc
*/
if (data_unit) {
if (!bio_dun(bio) && !memcmp(s_type, "sdcc", strlen("sdcc")))
*data_unit = 1 << ICE_CRYPTO_DATA_UNIT_512_B;
else
*data_unit = 1 << ICE_CRYPTO_DATA_UNIT_4_KB;
}
if (which_pfe != INVALID_PFE) {
/* Encrypted file; override ->bi_crypt_key */
pr_debug("parsing inode %lu with PFE type %d\n",
inode->i_ino, which_pfe);
return (*(pfk_parse_inode_ftable[which_pfe]))
(bio, inode, key_info, algo_mode, is_pfe);
}
/*
* bio is not for an encrypted file. Use ->bi_crypt_key if it was set.
* Otherwise, don't encrypt/decrypt the bio.
*/
#ifdef CONFIG_DM_DEFAULT_KEY
key = bio->bi_crypt_key;
#endif
if (!key) {
*is_pfe = false;
return -EINVAL;
}
/* Note: the "salt" is really just the second half of the XTS key. */
BUILD_BUG_ON(sizeof(key->raw) !=
PFK_SUPPORTED_KEY_SIZE + PFK_SUPPORTED_SALT_SIZE);
key_info->key = &key->raw[0];
key_info->key_size = PFK_SUPPORTED_KEY_SIZE;
key_info->salt = &key->raw[PFK_SUPPORTED_KEY_SIZE];
key_info->salt_size = PFK_SUPPORTED_SALT_SIZE;
if (algo_mode)
*algo_mode = ICE_CRYPTO_ALGO_MODE_AES_XTS;
return 0;
}
/**
* pfk_load_key_start() - loads PFE encryption key to the ICE
* Can also be invoked from non
* PFE context, in this case it
* is not relevant and is_pfe
* flag is set to false
*
* @bio: Pointer to the BIO structure
* @ice_setting: Pointer to ice setting structure that will be filled with
* ice configuration values, including the index to which the key was loaded
* @is_pfe: will be false if inode is not relevant to PFE, in such a case
* it should be treated as non PFE by the block layer
*
* Returns the index where the key is stored in encryption hw and additional
* information that will be used later for configuration of the encryption hw.
*
* Must be followed by pfk_load_key_end when key is no longer used by ice
*
*/
int pfk_load_key_start(const struct bio *bio,
struct ice_crypto_setting *ice_setting, bool *is_pfe,
bool async)
{
int ret = 0;
struct pfk_key_info key_info = {NULL, NULL, 0, 0};
enum ice_cryto_algo_mode algo_mode = ICE_CRYPTO_ALGO_MODE_AES_XTS;
enum ice_crpto_key_size key_size_type = 0;
unsigned int data_unit = 1 << ICE_CRYPTO_DATA_UNIT_512_B;
u32 key_index = 0;
if (!is_pfe) {
pr_err("is_pfe is NULL\n");
return -EINVAL;
}
/*
* only a few errors below can indicate that
* this function was not invoked within PFE context,
* otherwise we will consider it PFE
*/
*is_pfe = true;
if (!pfk_is_ready())
return -ENODEV;
if (!ice_setting) {
pr_err("ice setting is NULL\n");
return -EINVAL;
}
ret = pfk_get_key_for_bio(bio, &key_info, &algo_mode, is_pfe,
&data_unit);
if (ret != 0)
return ret;
ret = pfk_key_size_to_key_type(key_info.key_size, &key_size_type);
if (ret != 0)
return ret;
ret = pfk_kc_load_key_start(key_info.key, key_info.key_size,
key_info.salt, key_info.salt_size, &key_index, async,
data_unit);
if (ret) {
if (ret != -EBUSY && ret != -EAGAIN)
pr_err("start: could not load key into pfk key cache, error %d\n",
ret);
return ret;
}
ice_setting->key_size = key_size_type;
ice_setting->algo_mode = algo_mode;
/* hardcoded for now */
ice_setting->key_mode = ICE_CRYPTO_USE_LUT_SW_KEY;
ice_setting->key_index = key_index;
pr_debug("loaded key for file %s key_index %d\n",
inode_to_filename(pfk_bio_get_inode(bio)), key_index);
return 0;
}
/**
* pfk_load_key_end() - marks the PFE key as no longer used by ICE
* Can also be invoked from non
* PFE context, in this case it is not
* relevant and is_pfe flag is
* set to false
*
* @bio: Pointer to the BIO structure
* @is_pfe: Pointer to is_pfe flag, which will be true if function was invoked
* from PFE context
*/
int pfk_load_key_end(const struct bio *bio, bool *is_pfe)
{
int ret = 0;
struct pfk_key_info key_info = {NULL, NULL, 0, 0};
if (!is_pfe) {
pr_err("is_pfe is NULL\n");
return -EINVAL;
}
/* only a few errors below can indicate that
* this function was not invoked within PFE context,
* otherwise we will consider it PFE
*/
*is_pfe = true;
if (!pfk_is_ready())
return -ENODEV;
ret = pfk_get_key_for_bio(bio, &key_info, NULL, is_pfe, NULL);
if (ret != 0)
return ret;
pfk_kc_load_key_end(key_info.key, key_info.key_size,
key_info.salt, key_info.salt_size);
pr_debug("finished using key for file %s\n",
inode_to_filename(pfk_bio_get_inode(bio)));
return 0;
}
/**
* pfk_allow_merge_bio() - Check if 2 BIOs can be merged.
* @bio1: Pointer to first BIO structure.
* @bio2: Pointer to second BIO structure.
*
* Prevent merging of BIOs from encrypted and non-encrypted
* files, or files encrypted with different key.
* Also prevent non encrypted and encrypted data from the same file
* to be merged (ecryptfs header if stored inside file should be non
* encrypted)
* This API is called by the file system block layer.
*
* Return: true if the BIOs allowed to be merged, false
* otherwise.
*/
bool pfk_allow_merge_bio(const struct bio *bio1, const struct bio *bio2,
unsigned int sectors)
{
const struct blk_encryption_key *key1 = NULL;
const struct blk_encryption_key *key2 = NULL;
const struct inode *inode1;
const struct inode *inode2;
enum pfe_type which_pfe1;
enum pfe_type which_pfe2;
#ifdef CONFIG_DM_DEFAULT_KEY
key1 = bio1->bi_crypt_key;
key2 = bio2->bi_crypt_key;
#endif
if (!pfk_is_ready())
return false;
if (!bio1 || !bio2)
return false;
if (bio1 == bio2)
return true;
inode1 = pfk_bio_get_inode(bio1);
inode2 = pfk_bio_get_inode(bio2);
which_pfe1 = pfk_get_pfe_type(inode1);
which_pfe2 = pfk_get_pfe_type(inode2);
/*
* If one bio is for an encrypted file and the other is for a different
* type of encrypted file or for blocks that are not part of an
* encrypted file, do not merge.
*/
if (which_pfe1 != which_pfe2)
return false;
if (which_pfe1 != INVALID_PFE) {
/* Both bios are for the same type of encrypted file. */
return (*(pfk_allow_merge_bio_ftable[which_pfe1]))(bio1, bio2,
inode1, inode2, sectors);
}
/*
* Neither bio is for an encrypted file. Merge only if the default keys
* are the same (or both are NULL).
*/
return key1 == key2 ||
(key1 && key2 &&
!crypto_memneq(key1->raw, key2->raw, sizeof(key1->raw)));
}
int pfk_fbe_clear_key(const unsigned char *key, size_t key_size,
const unsigned char *salt, size_t salt_size)
{
int ret = -EINVAL;
if (!key || !salt)
return ret;
ret = pfk_kc_remove_key_with_salt(key, key_size, salt, salt_size);
if (ret)
pr_err("Clear key error: ret value %d\n", ret);
return ret;
}
/**
* Flush key table on storage core reset. During core reset key configuration
* is lost in ICE. We need to flash the cache, so that the keys will be
* reconfigured again for every subsequent transaction
*/
void pfk_clear_on_reset(void)
{
if (!pfk_is_ready())
return;
pfk_kc_clear_on_reset();
}
module_init(pfk_init);
module_exit(pfk_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Per-File-Key driver");