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
fscrypt_valid_enc_modes(u32 contents_mode,u32 filenames_mode)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 */
121