fs/crypto/fscrypt_private.h

   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_AES_128_ECB_KEY_SIZE         16
  22 #define FS_AES_128_CBC_KEY_SIZE         16
  23 #define FS_AES_128_CTS_KEY_SIZE         16
  24 #define FS_AES_256_GCM_KEY_SIZE         32
  25 #define FS_AES_256_CBC_KEY_SIZE         32
  26 #define FS_AES_256_CTS_KEY_SIZE         32
  27 #define FS_AES_256_XTS_KEY_SIZE         64
  28
  29 #define FS_KEY_DERIVATION_NONCE_SIZE            16
  30
  31 /**
  32  * Encryption context for inode
  33  *
  34  * Protector format:
  35  *  1 byte: Protector format (1 = this version)
  36  *  1 byte: File contents encryption mode
  37  *  1 byte: File names encryption mode
  38  *  1 byte: Flags
  39  *  8 bytes: Master Key descriptor
  40  *  16 bytes: Encryption Key derivation nonce
  41  */
  42 struct fscrypt_context {
  43         u8 format;
  44         u8 contents_encryption_mode;
  45         u8 filenames_encryption_mode;
  46         u8 flags;
  47         u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
  48         u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
  49 } __packed;
  50
  51 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1         1
  52
  53 /**
  54  * For encrypted symlinks, the ciphertext length is stored at the beginning
  55  * of the string in little-endian format.
  56  */
  57 struct fscrypt_symlink_data {
  58         __le16 len;
  59         char encrypted_path[1];
  60 } __packed;
  61
  62 /*
  63  * A pointer to this structure is stored in the file system's in-core
  64  * representation of an inode.
  65  */
  66 struct fscrypt_info {
  67         u8 ci_data_mode;
  68         u8 ci_filename_mode;
  69         u8 ci_flags;
  70         struct crypto_skcipher *ci_ctfm;
  71         struct crypto_cipher *ci_essiv_tfm;
  72         u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
  73 };
  74
  75 typedef enum {
  76         FS_DECRYPT = 0,
  77         FS_ENCRYPT,
  78 } fscrypt_direction_t;
  79
  80 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL         0x00000001
  81 #define FS_CTX_HAS_BOUNCE_BUFFER_FL             0x00000002
  82
  83 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
  84                                            u32 filenames_mode)
  85 {
  86         if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
  87             filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
  88                 return true;
  89
  90         if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
  91             filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
  92                 return true;
  93
  94         return false;
  95 }
  96
  97 /* crypto.c */
  98 extern struct kmem_cache *fscrypt_info_cachep;
  99 extern int fscrypt_initialize(unsigned int cop_flags);
 100 extern struct workqueue_struct *fscrypt_read_workqueue;
 101 extern int fscrypt_do_page_crypto(const struct inode *inode,
 102                                   fscrypt_direction_t rw, u64 lblk_num,
 103                                   struct page *src_page,
 104                                   struct page *dest_page,
 105                                   unsigned int len, unsigned int offs,
 106                                   gfp_t gfp_flags);
 107 extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
 108                                               gfp_t gfp_flags);
 109
 110 /* fname.c */
 111 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
 112                          u8 *out, unsigned int olen);
 113 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
 114                                          u32 orig_len, u32 max_len,
 115                                          u32 *encrypted_len_ret);
 116
 117 /* keyinfo.c */
 118 extern void __exit fscrypt_essiv_cleanup(void);
 119
 120 #endif /* _FSCRYPT_PRIVATE_H */