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_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  */
  34 struct 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  */
  49 struct 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  */
  58 struct 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
  67 typedef 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
  75 static 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         return false;
  87 }
  88
  89 /* crypto.c */
  90 extern struct kmem_cache *fscrypt_info_cachep;
  91 extern int fscrypt_initialize(unsigned int cop_flags);
  92 extern int fscrypt_do_page_crypto(const struct inode *inode,
  93                                   fscrypt_direction_t rw, u64 lblk_num,
  94                                   struct page *src_page,
  95                                   struct page *dest_page,
  96                                   unsigned int len, unsigned int offs,
  97                                   gfp_t gfp_flags);
  98 extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
  99                                               gfp_t gfp_flags);
 100 extern const struct dentry_operations fscrypt_d_ops;
 101
 102 extern void __printf(3, 4) __cold
 103 fscrypt_msg(struct super_block *sb, const char *level, const char *fmt, ...);
 104
 105 #define fscrypt_warn(sb, fmt, ...)              \
 106         fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__)
 107 #define fscrypt_err(sb, fmt, ...)               \
 108         fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__)
 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 */