1 /* SPDX-License-Identifier: GPL-2.0 */
5 * Copyright (C) 2015, Google, Inc.
7 * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
8 * Heavily modified since then.
11 #ifndef _FSCRYPT_PRIVATE_H
12 #define _FSCRYPT_PRIVATE_H
14 #include <linux/fscrypt.h>
15 #include <crypto/hash.h>
17 /* Encryption parameters */
18 #define FS_KEY_DERIVATION_NONCE_SIZE 16
21 * Encryption context for inode
24 * 1 byte: Protector format (1 = this version)
25 * 1 byte: File contents encryption mode
26 * 1 byte: File names encryption mode
28 * 8 bytes: Master Key descriptor
29 * 16 bytes: Encryption Key derivation nonce
31 struct fscrypt_context {
33 u8 contents_encryption_mode;
34 u8 filenames_encryption_mode;
36 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
37 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
40 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
43 * For encrypted symlinks, the ciphertext length is stored at the beginning
44 * of the string in little-endian format.
46 struct fscrypt_symlink_data {
48 char encrypted_path[1];
52 * fscrypt_info - the "encryption key" for an inode
54 * When an encrypted file's key is made available, an instance of this struct is
55 * allocated and stored in ->i_crypt_info. Once created, it remains until the
60 /* The actual crypto transform used for encryption and decryption */
61 struct crypto_skcipher *ci_ctfm;
64 * Cipher for ESSIV IV generation. Only set for CBC contents
65 * encryption, otherwise is NULL.
67 struct crypto_cipher *ci_essiv_tfm;
70 * Encryption mode used for this inode. It corresponds to either
71 * ci_data_mode or ci_filename_mode, depending on the inode type.
73 struct fscrypt_mode *ci_mode;
75 /* Back-pointer to the inode */
76 struct inode *ci_inode;
79 * If non-NULL, then encryption is done using the master key directly
80 * and ci_ctfm will equal ci_direct_key->dk_ctfm.
82 struct fscrypt_direct_key *ci_direct_key;
84 /* fields from the fscrypt_context */
88 u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
89 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
95 } fscrypt_direction_t;
97 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
99 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
102 if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
103 filenames_mode == FSCRYPT_MODE_AES_128_CTS)
106 if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
107 filenames_mode == FSCRYPT_MODE_AES_256_CTS)
110 if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
111 filenames_mode == FSCRYPT_MODE_ADIANTUM)
118 extern struct kmem_cache *fscrypt_info_cachep;
119 extern int fscrypt_initialize(unsigned int cop_flags);
120 extern int fscrypt_crypt_block(const struct inode *inode,
121 fscrypt_direction_t rw, u64 lblk_num,
122 struct page *src_page, struct page *dest_page,
123 unsigned int len, unsigned int offs,
125 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
126 extern const struct dentry_operations fscrypt_d_ops;
128 extern void __printf(3, 4) __cold
129 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
131 #define fscrypt_warn(inode, fmt, ...) \
132 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
133 #define fscrypt_err(inode, fmt, ...) \
134 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
136 #define FSCRYPT_MAX_IV_SIZE 32
140 /* logical block number within the file */
143 /* per-file nonce; only set in DIRECT_KEY mode */
144 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
146 u8 raw[FSCRYPT_MAX_IV_SIZE];
149 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
150 const struct fscrypt_info *ci);
153 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
154 u8 *out, unsigned int olen);
155 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
156 u32 orig_len, u32 max_len,
157 u32 *encrypted_len_ret);
161 struct fscrypt_mode {
162 const char *friendly_name;
163 const char *cipher_str;
166 bool logged_impl_name;
171 fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
173 return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
176 #endif /* _FSCRYPT_PRIVATE_H */