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 #include <linux/fscrypt.h> 16 #include <crypto/hash.h> 17 18 /* Encryption parameters */ 19 #define FS_KEY_DERIVATION_NONCE_SIZE 16 20 21 /** 22 * Encryption context for inode 23 * 24 * Protector format: 25 * 1 byte: Protector format (1 = this version) 26 * 1 byte: File contents encryption mode 27 * 1 byte: File names encryption mode 28 * 1 byte: Flags 29 * 8 bytes: Master Key descriptor 30 * 16 bytes: Encryption Key derivation nonce 31 */ 32 struct fscrypt_context { 33 u8 format; 34 u8 contents_encryption_mode; 35 u8 filenames_encryption_mode; 36 u8 flags; 37 u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; 38 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 39 } __packed; 40 41 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1 42 43 /** 44 * For encrypted symlinks, the ciphertext length is stored at the beginning 45 * of the string in little-endian format. 46 */ 47 struct fscrypt_symlink_data { 48 __le16 len; 49 char encrypted_path[1]; 50 } __packed; 51 52 /* 53 * fscrypt_info - the "encryption key" for an inode 54 * 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 57 * inode is evicted. 58 */ 59 struct fscrypt_info { 60 61 /* The actual crypto transform used for encryption and decryption */ 62 struct crypto_skcipher *ci_ctfm; 63 64 /* 65 * Cipher for ESSIV IV generation. Only set for CBC contents 66 * encryption, otherwise is NULL. 67 */ 68 struct crypto_cipher *ci_essiv_tfm; 69 70 /* 71 * Encryption mode used for this inode. It corresponds to either 72 * ci_data_mode or ci_filename_mode, depending on the inode type. 73 */ 74 struct fscrypt_mode *ci_mode; 75 76 /* 77 * If non-NULL, then this inode uses a master key directly rather than a 78 * derived key, and ci_ctfm will equal ci_master_key->mk_ctfm. 79 * Otherwise, this inode uses a derived key. 80 */ 81 struct fscrypt_master_key *ci_master_key; 82 83 /* fields from the fscrypt_context */ 84 u8 ci_data_mode; 85 u8 ci_filename_mode; 86 u8 ci_flags; 87 u8 ci_master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; 88 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 89 }; 90 91 typedef enum { 92 FS_DECRYPT = 0, 93 FS_ENCRYPT, 94 } fscrypt_direction_t; 95 96 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 97 98 static inline bool fscrypt_valid_enc_modes(u32 contents_mode, 99 u32 filenames_mode) 100 { 101 if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC && 102 filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS) 103 return true; 104 105 if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS && 106 filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS) 107 return true; 108 109 if (contents_mode == FS_ENCRYPTION_MODE_ADIANTUM && 110 filenames_mode == FS_ENCRYPTION_MODE_ADIANTUM) 111 return true; 112 113 return false; 114 } 115 116 /* crypto.c */ 117 extern struct kmem_cache *fscrypt_info_cachep; 118 extern int fscrypt_initialize(unsigned int cop_flags); 119 extern int fscrypt_crypt_block(const struct inode *inode, 120 fscrypt_direction_t rw, u64 lblk_num, 121 struct page *src_page, struct page *dest_page, 122 unsigned int len, unsigned int offs, 123 gfp_t gfp_flags); 124 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); 125 extern const struct dentry_operations fscrypt_d_ops; 126 127 extern void __printf(3, 4) __cold 128 fscrypt_msg(struct super_block *sb, const char *level, const char *fmt, ...); 129 130 #define fscrypt_warn(sb, fmt, ...) \ 131 fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__) 132 #define fscrypt_err(sb, fmt, ...) \ 133 fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__) 134 135 #define FSCRYPT_MAX_IV_SIZE 32 136 137 union fscrypt_iv { 138 struct { 139 /* logical block number within the file */ 140 __le64 lblk_num; 141 142 /* per-file nonce; only set in DIRECT_KEY mode */ 143 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 144 }; 145 u8 raw[FSCRYPT_MAX_IV_SIZE]; 146 }; 147 148 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, 149 const struct fscrypt_info *ci); 150 151 /* fname.c */ 152 extern int fname_encrypt(struct inode *inode, const struct qstr *iname, 153 u8 *out, unsigned int olen); 154 extern bool fscrypt_fname_encrypted_size(const struct inode *inode, 155 u32 orig_len, u32 max_len, 156 u32 *encrypted_len_ret); 157 158 /* keyinfo.c */ 159 160 struct fscrypt_mode { 161 const char *friendly_name; 162 const char *cipher_str; 163 int keysize; 164 int ivsize; 165 bool logged_impl_name; 166 bool needs_essiv; 167 }; 168 169 extern void __exit fscrypt_essiv_cleanup(void); 170 171 #endif /* _FSCRYPT_PRIVATE_H */ 172