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 #define CONST_STRLEN(str) (sizeof(str) - 1)
19 #define FS_KEY_DERIVATION_NONCE_SIZE 16
21 #define FSCRYPT_MIN_KEY_SIZE 16
24 * Encryption context for inode
27 * 1 byte: Protector format (1 = this version)
28 * 1 byte: File contents encryption mode
29 * 1 byte: File names encryption mode
31 * 8 bytes: Master Key descriptor
32 * 16 bytes: Encryption Key derivation nonce
34 struct fscrypt_context {
36 u8 contents_encryption_mode;
37 u8 filenames_encryption_mode;
39 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
40 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
43 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
46 * For encrypted symlinks, the ciphertext length is stored at the beginning
47 * of the string in little-endian format.
49 struct fscrypt_symlink_data {
51 char encrypted_path[1];
55 * fscrypt_info - the "encryption key" for an inode
57 * When an encrypted file's key is made available, an instance of this struct is
58 * allocated and stored in ->i_crypt_info. Once created, it remains until the
63 /* The actual crypto transform used for encryption and decryption */
64 struct crypto_skcipher *ci_ctfm;
67 * Cipher for ESSIV IV generation. Only set for CBC contents
68 * encryption, otherwise is NULL.
70 struct crypto_cipher *ci_essiv_tfm;
73 * Encryption mode used for this inode. It corresponds to either
74 * ci_data_mode or ci_filename_mode, depending on the inode type.
76 struct fscrypt_mode *ci_mode;
78 /* Back-pointer to the inode */
79 struct inode *ci_inode;
82 * If non-NULL, then encryption is done using the master key directly
83 * and ci_ctfm will equal ci_direct_key->dk_ctfm.
85 struct fscrypt_direct_key *ci_direct_key;
87 /* fields from the fscrypt_context */
91 u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
92 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
98 } fscrypt_direction_t;
100 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
102 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
105 if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
106 filenames_mode == FSCRYPT_MODE_AES_128_CTS)
109 if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
110 filenames_mode == FSCRYPT_MODE_AES_256_CTS)
113 if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
114 filenames_mode == FSCRYPT_MODE_ADIANTUM)
121 extern struct kmem_cache *fscrypt_info_cachep;
122 extern int fscrypt_initialize(unsigned int cop_flags);
123 extern int fscrypt_crypt_block(const struct inode *inode,
124 fscrypt_direction_t rw, u64 lblk_num,
125 struct page *src_page, struct page *dest_page,
126 unsigned int len, unsigned int offs,
128 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
129 extern const struct dentry_operations fscrypt_d_ops;
131 extern void __printf(3, 4) __cold
132 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
134 #define fscrypt_warn(inode, fmt, ...) \
135 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
136 #define fscrypt_err(inode, fmt, ...) \
137 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
139 #define FSCRYPT_MAX_IV_SIZE 32
143 /* logical block number within the file */
146 /* per-file nonce; only set in DIRECT_KEY mode */
147 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
149 u8 raw[FSCRYPT_MAX_IV_SIZE];
152 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
153 const struct fscrypt_info *ci);
156 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
157 u8 *out, unsigned int olen);
158 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
159 u32 orig_len, u32 max_len,
160 u32 *encrypted_len_ret);
165 * fscrypt_master_key_secret - secret key material of an in-use master key
167 struct fscrypt_master_key_secret {
169 /* Size of the raw key in bytes */
173 u8 raw[FSCRYPT_MAX_KEY_SIZE];
175 } __randomize_layout;
178 * fscrypt_master_key - an in-use master key
180 * This represents a master encryption key which has been added to the
181 * filesystem and can be used to "unlock" the encrypted files which were
184 struct fscrypt_master_key {
186 /* The secret key material */
187 struct fscrypt_master_key_secret mk_secret;
189 /* Arbitrary key descriptor which was assigned by userspace */
190 struct fscrypt_key_specifier mk_spec;
192 } __randomize_layout;
194 static inline const char *master_key_spec_type(
195 const struct fscrypt_key_specifier *spec)
197 switch (spec->type) {
198 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
204 static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
206 switch (spec->type) {
207 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
208 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
214 fscrypt_find_master_key(struct super_block *sb,
215 const struct fscrypt_key_specifier *mk_spec);
217 extern int __init fscrypt_init_keyring(void);
221 struct fscrypt_mode {
222 const char *friendly_name;
223 const char *cipher_str;
226 bool logged_impl_name;
231 fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
233 return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
236 extern struct crypto_skcipher *
237 fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
238 const struct inode *inode);
240 extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
241 const u8 *derived_key);
245 extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
247 extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
248 const u8 *raw_master_key);
250 extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
251 struct fscrypt_info *ci);
253 #endif /* _FSCRYPT_PRIVATE_H */