1 /*
2  * linux/fs/f2fs/f2fs_crypto.h
3  *
4  * Copied from linux/fs/ext4/ext4_crypto.h
5  *
6  * Copyright (C) 2015, Google, Inc.
7  *
8  * This contains encryption header content for f2fs
9  *
10  * Written by Michael Halcrow, 2015.
11  * Modified by Jaegeuk Kim, 2015.
12  */
13 #ifndef _F2FS_CRYPTO_H
14 #define _F2FS_CRYPTO_H
15 
16 #include <linux/fs.h>
17 
18 #define F2FS_KEY_DESCRIPTOR_SIZE	8
19 
20 /* Policy provided via an ioctl on the topmost directory */
21 struct f2fs_encryption_policy {
22 	char version;
23 	char contents_encryption_mode;
24 	char filenames_encryption_mode;
25 	char flags;
26 	char master_key_descriptor[F2FS_KEY_DESCRIPTOR_SIZE];
27 } __attribute__((__packed__));
28 
29 #define F2FS_ENCRYPTION_CONTEXT_FORMAT_V1	1
30 #define F2FS_KEY_DERIVATION_NONCE_SIZE		16
31 
32 #define F2FS_POLICY_FLAGS_PAD_4		0x00
33 #define F2FS_POLICY_FLAGS_PAD_8		0x01
34 #define F2FS_POLICY_FLAGS_PAD_16	0x02
35 #define F2FS_POLICY_FLAGS_PAD_32	0x03
36 #define F2FS_POLICY_FLAGS_PAD_MASK	0x03
37 #define F2FS_POLICY_FLAGS_VALID		0x03
38 
39 /**
40  * Encryption context for inode
41  *
42  * Protector format:
43  *  1 byte: Protector format (1 = this version)
44  *  1 byte: File contents encryption mode
45  *  1 byte: File names encryption mode
46  *  1 byte: Flags
47  *  8 bytes: Master Key descriptor
48  *  16 bytes: Encryption Key derivation nonce
49  */
50 struct f2fs_encryption_context {
51 	char format;
52 	char contents_encryption_mode;
53 	char filenames_encryption_mode;
54 	char flags;
55 	char master_key_descriptor[F2FS_KEY_DESCRIPTOR_SIZE];
56 	char nonce[F2FS_KEY_DERIVATION_NONCE_SIZE];
57 } __attribute__((__packed__));
58 
59 /* Encryption parameters */
60 #define F2FS_XTS_TWEAK_SIZE 16
61 #define F2FS_AES_128_ECB_KEY_SIZE 16
62 #define F2FS_AES_256_GCM_KEY_SIZE 32
63 #define F2FS_AES_256_CBC_KEY_SIZE 32
64 #define F2FS_AES_256_CTS_KEY_SIZE 32
65 #define F2FS_AES_256_XTS_KEY_SIZE 64
66 #define F2FS_MAX_KEY_SIZE 64
67 
68 #define F2FS_KEY_DESC_PREFIX "f2fs:"
69 #define F2FS_KEY_DESC_PREFIX_SIZE 5
70 
71 struct f2fs_encryption_key {
72 	__u32 mode;
73 	char raw[F2FS_MAX_KEY_SIZE];
74 	__u32 size;
75 } __attribute__((__packed__));
76 
77 struct f2fs_crypt_info {
78 	char		ci_data_mode;
79 	char		ci_filename_mode;
80 	char		ci_flags;
81 	struct crypto_ablkcipher *ci_ctfm;
82 	struct key	*ci_keyring_key;
83 	char		ci_master_key[F2FS_KEY_DESCRIPTOR_SIZE];
84 };
85 
86 #define F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL             0x00000001
87 #define F2FS_WRITE_PATH_FL			      0x00000002
88 
89 struct f2fs_crypto_ctx {
90 	union {
91 		struct {
92 			struct page *bounce_page;       /* Ciphertext page */
93 			struct page *control_page;      /* Original page  */
94 		} w;
95 		struct {
96 			struct bio *bio;
97 			struct work_struct work;
98 		} r;
99 		struct list_head free_list;     /* Free list */
100 	};
101 	char flags;                      /* Flags */
102 };
103 
104 struct f2fs_completion_result {
105 	struct completion completion;
106 	int res;
107 };
108 
109 #define DECLARE_F2FS_COMPLETION_RESULT(ecr) \
110 	struct f2fs_completion_result ecr = { \
111 		COMPLETION_INITIALIZER((ecr).completion), 0 }
112 
f2fs_encryption_key_size(int mode)113 static inline int f2fs_encryption_key_size(int mode)
114 {
115 	switch (mode) {
116 	case F2FS_ENCRYPTION_MODE_AES_256_XTS:
117 		return F2FS_AES_256_XTS_KEY_SIZE;
118 	case F2FS_ENCRYPTION_MODE_AES_256_GCM:
119 		return F2FS_AES_256_GCM_KEY_SIZE;
120 	case F2FS_ENCRYPTION_MODE_AES_256_CBC:
121 		return F2FS_AES_256_CBC_KEY_SIZE;
122 	case F2FS_ENCRYPTION_MODE_AES_256_CTS:
123 		return F2FS_AES_256_CTS_KEY_SIZE;
124 	default:
125 		BUG();
126 	}
127 	return 0;
128 }
129 
130 #define F2FS_FNAME_NUM_SCATTER_ENTRIES	4
131 #define F2FS_CRYPTO_BLOCK_SIZE		16
132 #define F2FS_FNAME_CRYPTO_DIGEST_SIZE	32
133 
134 /**
135  * For encrypted symlinks, the ciphertext length is stored at the beginning
136  * of the string in little-endian format.
137  */
138 struct f2fs_encrypted_symlink_data {
139 	__le16 len;
140 	char encrypted_path[1];
141 } __attribute__((__packed__));
142 
143 /**
144  * This function is used to calculate the disk space required to
145  * store a filename of length l in encrypted symlink format.
146  */
encrypted_symlink_data_len(u32 l)147 static inline u32 encrypted_symlink_data_len(u32 l)
148 {
149 	return (l + sizeof(struct f2fs_encrypted_symlink_data) - 1);
150 }
151 #endif	/* _F2FS_CRYPTO_H */
152