1 /*
2 * fscrypt_private.h
3 *
4 * Copyright (C) 2015, Google, Inc.
5 *
6 * This contains encryption key functions.
7 *
8 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
9 */
10
11 #ifndef _FSCRYPT_PRIVATE_H
12 #define _FSCRYPT_PRIVATE_H
13
14 #define __FS_HAS_ENCRYPTION 1
15 #include <linux/fscrypt.h>
16 #include <crypto/hash.h>
17
18 /* Encryption parameters */
19 #define FS_IV_SIZE 16
20 #define FS_AES_128_ECB_KEY_SIZE 16
21 #define FS_AES_128_CBC_KEY_SIZE 16
22 #define FS_AES_128_CTS_KEY_SIZE 16
23 #define FS_AES_256_GCM_KEY_SIZE 32
24 #define FS_AES_256_CBC_KEY_SIZE 32
25 #define FS_AES_256_CTS_KEY_SIZE 32
26 #define FS_AES_256_XTS_KEY_SIZE 64
27
28 #define FS_KEY_DERIVATION_NONCE_SIZE 16
29
30 /**
31 * Encryption context for inode
32 *
33 * Protector format:
34 * 1 byte: Protector format (1 = this version)
35 * 1 byte: File contents encryption mode
36 * 1 byte: File names encryption mode
37 * 1 byte: Flags
38 * 8 bytes: Master Key descriptor
39 * 16 bytes: Encryption Key derivation nonce
40 */
41 struct fscrypt_context {
42 u8 format;
43 u8 contents_encryption_mode;
44 u8 filenames_encryption_mode;
45 u8 flags;
46 u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
47 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
48 } __packed;
49
50 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
51
52 /**
53 * For encrypted symlinks, the ciphertext length is stored at the beginning
54 * of the string in little-endian format.
55 */
56 struct fscrypt_symlink_data {
57 __le16 len;
58 char encrypted_path[1];
59 } __packed;
60
61 /*
62 * A pointer to this structure is stored in the file system's in-core
63 * representation of an inode.
64 */
65 struct fscrypt_info {
66 u8 ci_data_mode;
67 u8 ci_filename_mode;
68 u8 ci_flags;
69 struct crypto_skcipher *ci_ctfm;
70 struct crypto_cipher *ci_essiv_tfm;
71 u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
72 };
73
74 typedef enum {
75 FS_DECRYPT = 0,
76 FS_ENCRYPT,
77 } fscrypt_direction_t;
78
79 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
80 #define FS_CTX_HAS_BOUNCE_BUFFER_FL 0x00000002
81
fscrypt_valid_enc_modes(u32 contents_mode,u32 filenames_mode)82 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
83 u32 filenames_mode)
84 {
85 if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
86 filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
87 return true;
88
89 if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
90 filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
91 return true;
92
93 return false;
94 }
95
96 /* crypto.c */
97 extern struct kmem_cache *fscrypt_info_cachep;
98 extern int fscrypt_initialize(unsigned int cop_flags);
99 extern int fscrypt_do_page_crypto(const struct inode *inode,
100 fscrypt_direction_t rw, u64 lblk_num,
101 struct page *src_page,
102 struct page *dest_page,
103 unsigned int len, unsigned int offs,
104 gfp_t gfp_flags);
105 extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
106 gfp_t gfp_flags);
107
108 /* fname.c */
109 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
110 u8 *out, unsigned int olen);
111 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
112 u32 orig_len, u32 max_len,
113 u32 *encrypted_len_ret);
114
115 /* keyinfo.c */
116 extern void __exit fscrypt_essiv_cleanup(void);
117
118 #endif /* _FSCRYPT_PRIVATE_H */
119