1 /* SPDX-License-Identifier: GPL-2.0 */
5 * Copyright (C) 2015, Google, Inc.
7 * This contains encryption key functions.
9 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
12 #ifndef _FSCRYPT_PRIVATE_H
13 #define _FSCRYPT_PRIVATE_H
15 #include <linux/fscrypt.h>
16 #include <crypto/hash.h>
18 /* Encryption parameters */
19 #define FS_KEY_DERIVATION_NONCE_SIZE 16
22 * Encryption context for inode
25 * 1 byte: Protector format (1 = this version)
26 * 1 byte: File contents encryption mode
27 * 1 byte: File names encryption mode
29 * 8 bytes: Master Key descriptor
30 * 16 bytes: Encryption Key derivation nonce
32 struct fscrypt_context {
34 u8 contents_encryption_mode;
35 u8 filenames_encryption_mode;
37 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
38 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
41 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
44 * For encrypted symlinks, the ciphertext length is stored at the beginning
45 * of the string in little-endian format.
47 struct fscrypt_symlink_data {
49 char encrypted_path[1];
53 * fscrypt_info - the "encryption key" for an inode
55 * When an encrypted file's key is made available, an instance of this struct is
56 * allocated and stored in ->i_crypt_info. Once created, it remains until the
61 /* The actual crypto transform used for encryption and decryption */
62 struct crypto_skcipher *ci_ctfm;
65 * Cipher for ESSIV IV generation. Only set for CBC contents
66 * encryption, otherwise is NULL.
68 struct crypto_cipher *ci_essiv_tfm;
71 * Encryption mode used for this inode. It corresponds to either
72 * ci_data_mode or ci_filename_mode, depending on the inode type.
74 struct fscrypt_mode *ci_mode;
76 /* Back-pointer to the inode */
77 struct inode *ci_inode;
80 * If non-NULL, then encryption is done using the master key directly
81 * and ci_ctfm will equal ci_direct_key->dk_ctfm.
83 struct fscrypt_direct_key *ci_direct_key;
85 /* fields from the fscrypt_context */
89 u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
90 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
96 } fscrypt_direction_t;
98 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
100 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
103 if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
104 filenames_mode == FSCRYPT_MODE_AES_128_CTS)
107 if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
108 filenames_mode == FSCRYPT_MODE_AES_256_CTS)
111 if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
112 filenames_mode == FSCRYPT_MODE_ADIANTUM)
119 extern struct kmem_cache *fscrypt_info_cachep;
120 extern int fscrypt_initialize(unsigned int cop_flags);
121 extern int fscrypt_crypt_block(const struct inode *inode,
122 fscrypt_direction_t rw, u64 lblk_num,
123 struct page *src_page, struct page *dest_page,
124 unsigned int len, unsigned int offs,
126 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
127 extern const struct dentry_operations fscrypt_d_ops;
129 extern void __printf(3, 4) __cold
130 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
132 #define fscrypt_warn(inode, fmt, ...) \
133 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
134 #define fscrypt_err(inode, fmt, ...) \
135 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
137 #define FSCRYPT_MAX_IV_SIZE 32
141 /* logical block number within the file */
144 /* per-file nonce; only set in DIRECT_KEY mode */
145 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
147 u8 raw[FSCRYPT_MAX_IV_SIZE];
150 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
151 const struct fscrypt_info *ci);
154 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
155 u8 *out, unsigned int olen);
156 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
157 u32 orig_len, u32 max_len,
158 u32 *encrypted_len_ret);
162 struct fscrypt_mode {
163 const char *friendly_name;
164 const char *cipher_str;
167 bool logged_impl_name;
171 #endif /* _FSCRYPT_PRIVATE_H */