LXR linux/fs/crypto/fscrypt

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * fscrypt_private.h
   4 *
   5 * Copyright (C) 2015, Google, Inc.
   6 *
   7 * This contains encryption key functions.
   8 *
   9 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
  10 */
  11
  12#ifndef _FSCRYPT_PRIVATE_H
  13#define _FSCRYPT_PRIVATE_H
  14
  15#define __FS_HAS_ENCRYPTION 1
  16#include <linux/fscrypt.h>
  17#include <crypto/hash.h>
  18
  19/* Encryption parameters */
  20#define FS_IV_SIZE                      16
  21#define FS_KEY_DERIVATION_NONCE_SIZE    16
  22
  23/**
  24 * Encryption context for inode
  25 *
  26 * Protector format:
  27 *  1 byte: Protector format (1 = this version)
  28 *  1 byte: File contents encryption mode
  29 *  1 byte: File names encryption mode
  30 *  1 byte: Flags
  31 *  8 bytes: Master Key descriptor
  32 *  16 bytes: Encryption Key derivation nonce
  33 */
  34struct fscrypt_context {
  35        u8 format;
  36        u8 contents_encryption_mode;
  37        u8 filenames_encryption_mode;
  38        u8 flags;
  39        u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
  40        u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
  41} __packed;
  42
  43#define FS_ENCRYPTION_CONTEXT_FORMAT_V1         1
  44
  45/**
  46 * For encrypted symlinks, the ciphertext length is stored at the beginning
  47 * of the string in little-endian format.
  48 */
  49struct fscrypt_symlink_data {
  50        __le16 len;
  51        char encrypted_path[1];
  52} __packed;
  53
  54/*
  55 * A pointer to this structure is stored in the file system's in-core
  56 * representation of an inode.
  57 */
  58struct fscrypt_info {
  59        u8 ci_data_mode;
  60        u8 ci_filename_mode;
  61        u8 ci_flags;
  62        struct crypto_skcipher *ci_ctfm;
  63        struct crypto_cipher *ci_essiv_tfm;
  64        u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
  65};
  66
  67typedef enum {
  68        FS_DECRYPT = 0,
  69        FS_ENCRYPT,
  70} fscrypt_direction_t;
  71
  72#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL         0x00000001
  73#define FS_CTX_HAS_BOUNCE_BUFFER_FL             0x00000002
  74
  75static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
  76                                           u32 filenames_mode)
  77{
  78        if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
  79            filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
  80                return true;
  81
  82        if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
  83            filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
  84                return true;
  85
  86        if (contents_mode == FS_ENCRYPTION_MODE_SPECK128_256_XTS &&
  87            filenames_mode == FS_ENCRYPTION_MODE_SPECK128_256_CTS)
  88                return true;
  89
  90        return false;
  91}
  92
  93/* crypto.c */
  94extern struct kmem_cache *fscrypt_info_cachep;
  95extern int fscrypt_initialize(unsigned int cop_flags);
  96extern int fscrypt_do_page_crypto(const struct inode *inode,
  97                                  fscrypt_direction_t rw, u64 lblk_num,
  98                                  struct page *src_page,
  99                                  struct page *dest_page,
 100                                  unsigned int len, unsigned int offs,
 101                                  gfp_t gfp_flags);
 102extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
 103                                              gfp_t gfp_flags);
 104extern const struct dentry_operations fscrypt_d_ops;
 105
 106extern void __printf(3, 4) __cold
 107fscrypt_msg(struct super_block *sb, const char *level, const char *fmt, ...);
 108
 109#define fscrypt_warn(sb, fmt, ...)              \
 110        fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__)
 111#define fscrypt_err(sb, fmt, ...)               \
 112        fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__)
 113
 114/* fname.c */
 115extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
 116                         u8 *out, unsigned int olen);
 117extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
 118                                         u32 orig_len, u32 max_len,
 119                                         u32 *encrypted_len_ret);
 120
 121/* keyinfo.c */
 122extern void __exit fscrypt_essiv_cleanup(void);
 123
 124#endif /* _FSCRYPT_PRIVATE_H */
 125