| /** |
| * eCryptfs: Linux filesystem encryption layer |
| * Copyright (c) 2015-2016, 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. |
| */ |
| |
| #include <linux/string.h> |
| #include <linux/ecryptfs.h> |
| #include <linux/mutex.h> |
| #include <linux/types.h> |
| #include <linux/slab.h> |
| #include <linux/pagemap.h> |
| #include <linux/random.h> |
| #include "ecryptfs_kernel.h" |
| |
| static DEFINE_MUTEX(events_mutex); |
| struct ecryptfs_events *events_ptr = NULL; |
| |
| void ecryptfs_free_events(void) |
| { |
| mutex_lock(&events_mutex); |
| if (events_ptr != NULL) { |
| kfree(events_ptr); |
| events_ptr = NULL; |
| } |
| |
| mutex_unlock(&events_mutex); |
| } |
| |
| /** |
| * Given ecryptfs data, the function |
| * returns appropriate key size. |
| */ |
| size_t ecryptfs_get_key_size(const void *data) |
| { |
| |
| struct ecryptfs_crypt_stat *stat = NULL; |
| |
| if (!data) |
| return 0; |
| |
| stat = (struct ecryptfs_crypt_stat *)data; |
| return stat->key_size; |
| } |
| |
| /** |
| * Given ecryptfs data, the function |
| * returns appropriate salt size. |
| * |
| * !!! crypt_stat cipher name and mode must be initialized |
| */ |
| size_t ecryptfs_get_salt_size(const void *data) |
| { |
| if (!data) { |
| ecryptfs_printk(KERN_ERR, |
| "ecryptfs_get_salt_size: invalid data parameter\n"); |
| return 0; |
| } |
| |
| return ecryptfs_get_salt_size_for_cipher(data); |
| |
| } |
| |
| /** |
| * Given ecryptfs data, the function |
| * returns file encryption key. |
| */ |
| const unsigned char *ecryptfs_get_key(const void *data) |
| { |
| |
| struct ecryptfs_crypt_stat *stat = NULL; |
| |
| if (!data) { |
| ecryptfs_printk(KERN_ERR, |
| "ecryptfs_get_key: invalid data parameter\n"); |
| return NULL; |
| } |
| stat = (struct ecryptfs_crypt_stat *)data; |
| return stat->key; |
| } |
| |
| /** |
| * Given ecryptfs data, the function |
| * returns file encryption salt. |
| */ |
| const unsigned char *ecryptfs_get_salt(const void *data) |
| { |
| struct ecryptfs_crypt_stat *stat = NULL; |
| |
| if (!data) { |
| ecryptfs_printk(KERN_ERR, |
| "ecryptfs_get_salt: invalid data parameter\n"); |
| return NULL; |
| } |
| stat = (struct ecryptfs_crypt_stat *)data; |
| return stat->key + ecryptfs_get_salt_size(data); |
| } |
| |
| /** |
| * Returns ecryptfs events pointer |
| */ |
| inline struct ecryptfs_events *get_events(void) |
| { |
| return events_ptr; |
| } |
| |
| /** |
| * If external crypto module requires salt in addition to key, |
| * we store it as part of key array (if there is enough space) |
| * Checks whether a salt key can fit into array allocated for |
| * regular key |
| */ |
| bool ecryptfs_check_space_for_salt(const size_t key_size, |
| const size_t salt_size) |
| { |
| if ((salt_size + key_size) > ECRYPTFS_MAX_KEY_BYTES) |
| return false; |
| |
| return true; |
| } |
| |
| /* |
| * If there is salt that is used by external crypto module, it is stored |
| * in the same array where regular key is. Salt is going to be used by |
| * external crypto module only, so for all internal crypto operations salt |
| * should be ignored. |
| * |
| * Get key size in cases where it is going to be used for data encryption |
| * or for all other general purposes |
| */ |
| size_t ecryptfs_get_key_size_to_enc_data( |
| const struct ecryptfs_crypt_stat *crypt_stat) |
| { |
| if (!crypt_stat) |
| return 0; |
| |
| return crypt_stat->key_size; |
| } |
| |
| /* |
| * If there is salt that is used by external crypto module, it is stored |
| * in the same array where regular key is. Salt is going to be used by |
| * external crypto module only, but we still need to save and restore it |
| * (in encrypted form) as part of ecryptfs header along with the regular |
| * key. |
| * |
| * Get key size in cases where it is going to be stored persistently |
| * |
| * !!! crypt_stat cipher name and mode must be initialized |
| */ |
| size_t ecryptfs_get_key_size_to_store_key( |
| const struct ecryptfs_crypt_stat *crypt_stat) |
| { |
| size_t salt_size = 0; |
| |
| if (!crypt_stat) |
| return 0; |
| |
| salt_size = ecryptfs_get_salt_size(crypt_stat); |
| |
| if (!ecryptfs_check_space_for_salt(crypt_stat->key_size, salt_size)) { |
| ecryptfs_printk(KERN_WARNING, |
| "ecryptfs_get_key_size_to_store_key: not enough space for salt\n"); |
| return crypt_stat->key_size; |
| } |
| |
| return crypt_stat->key_size + salt_size; |
| } |
| |
| /* |
| * If there is salt that is used by external crypto module, it is stored |
| * in the same array where regular key is. Salt is going to be used by |
| * external crypto module only, but we still need to save and restore it |
| * (in encrypted form) as part of ecryptfs header along with the regular |
| * key. |
| * |
| * Get key size in cases where it is going to be restored from storage |
| * |
| * !!! crypt_stat cipher name and mode must be initialized |
| */ |
| size_t ecryptfs_get_key_size_to_restore_key(size_t stored_key_size, |
| const struct ecryptfs_crypt_stat *crypt_stat) |
| { |
| size_t salt_size = 0; |
| |
| if (!crypt_stat) |
| return 0; |
| |
| salt_size = ecryptfs_get_salt_size_for_cipher(crypt_stat); |
| |
| if (salt_size >= stored_key_size) { |
| ecryptfs_printk(KERN_WARNING, |
| "ecryptfs_get_key_size_to_restore_key: salt %zu >= stred size %zu\n", |
| salt_size, stored_key_size); |
| |
| return stored_key_size; |
| } |
| |
| return stored_key_size - salt_size; |
| } |
| |
| /** |
| * Given crypt_stat, the function returns appropriate salt size. |
| */ |
| size_t ecryptfs_get_salt_size_for_cipher( |
| const struct ecryptfs_crypt_stat *crypt_stat) |
| { |
| if (!get_events() || !(get_events()->get_salt_key_size_cb)) |
| return 0; |
| |
| return get_events()->get_salt_key_size_cb(crypt_stat); |
| } |
| |
| /** |
| * Given mount_crypt_stat, the function returns appropriate salt size. |
| */ |
| size_t ecryptfs_get_salt_size_for_cipher_mount( |
| const struct ecryptfs_mount_crypt_stat *crypt_stat) |
| { |
| if (!get_events() || !(get_events()->get_salt_key_size_cb)) |
| return 0; |
| |
| return get_events()->get_salt_key_size_cb(crypt_stat); |
| } |
| |