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_KEY_DERIVATION_NONCE_SIZE 16 21 22 /** 23 * Encryption context for inode 24 * 25 * Protector format: 26 * 1 byte: Protector format (1 = this version) 27 * 1 byte: File contents encryption mode 28 * 1 byte: File names encryption mode 29 * 1 byte: Flags 30 * 8 bytes: Master Key descriptor 31 * 16 bytes: Encryption Key derivation nonce 32 */ 33 struct fscrypt_context { 34 u8 format; 35 u8 contents_encryption_mode; 36 u8 filenames_encryption_mode; 37 u8 flags; 38 u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; 39 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 40 } __packed; 41 42 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1 43 44 /** 45 * For encrypted symlinks, the ciphertext length is stored at the beginning 46 * of the string in little-endian format. 47 */ 48 struct fscrypt_symlink_data { 49 __le16 len; 50 char encrypted_path[1]; 51 } __packed; 52 53 /* 54 * fscrypt_info - the "encryption key" for an inode 55 * 56 * When an encrypted file's key is made available, an instance of this struct is 57 * allocated and stored in ->i_crypt_info. Once created, it remains until the 58 * inode is evicted. 59 */ 60 struct fscrypt_info { 61 62 /* The actual crypto transform used for encryption and decryption */ 63 struct crypto_skcipher *ci_ctfm; 64 65 /* 66 * Cipher for ESSIV IV generation. Only set for CBC contents 67 * encryption, otherwise is NULL. 68 */ 69 struct crypto_cipher *ci_essiv_tfm; 70 71 /* 72 * Encryption mode used for this inode. It corresponds to either 73 * ci_data_mode or ci_filename_mode, depending on the inode type. 74 */ 75 struct fscrypt_mode *ci_mode; 76 77 /* 78 * If non-NULL, then this inode uses a master key directly rather than a 79 * derived key, and ci_ctfm will equal ci_master_key->mk_ctfm. 80 * Otherwise, this inode uses a derived key. 81 */ 82 struct fscrypt_master_key *ci_master_key; 83 84 /* fields from the fscrypt_context */ 85 u8 ci_data_mode; 86 u8 ci_filename_mode; 87 u8 ci_flags; 88 u8 ci_master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; 89 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 90 }; 91 92 typedef enum { 93 FS_DECRYPT = 0, 94 FS_ENCRYPT, 95 } fscrypt_direction_t; 96 97 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 98 #define FS_CTX_HAS_BOUNCE_BUFFER_FL 0x00000002 99 100 static inline bool fscrypt_valid_enc_modes(u32 contents_mode, 101 u32 filenames_mode) 102 { 103 if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC && 104 filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS) 105 return true; 106 107 if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS && 108 filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS) 109 return true; 110 111 if (contents_mode == FS_ENCRYPTION_MODE_ADIANTUM && 112 filenames_mode == FS_ENCRYPTION_MODE_ADIANTUM) 113 return true; 114 115 return false; 116 } 117 118 /* crypto.c */ 119 extern struct kmem_cache *fscrypt_info_cachep; 120 extern int fscrypt_initialize(unsigned int cop_flags); 121 extern int fscrypt_do_page_crypto(const struct inode *inode, 122 fscrypt_direction_t rw, u64 lblk_num, 123 struct page *src_page, 124 struct page *dest_page, 125 unsigned int len, unsigned int offs, 126 gfp_t gfp_flags); 127 extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx, 128 gfp_t gfp_flags); 129 extern const struct dentry_operations fscrypt_d_ops; 130 131 extern void __printf(3, 4) __cold 132 fscrypt_msg(struct super_block *sb, const char *level, const char *fmt, ...); 133 134 #define fscrypt_warn(sb, fmt, ...) \ 135 fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__) 136 #define fscrypt_err(sb, fmt, ...) \ 137 fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__) 138 139 #define FSCRYPT_MAX_IV_SIZE 32 140 141 union fscrypt_iv { 142 struct { 143 /* logical block number within the file */ 144 __le64 lblk_num; 145 146 /* per-file nonce; only set in DIRECT_KEY mode */ 147 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; 148 }; 149 u8 raw[FSCRYPT_MAX_IV_SIZE]; 150 }; 151 152 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, 153 const struct fscrypt_info *ci); 154 155 /* fname.c */ 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); 161 162 /* keyinfo.c */ 163 164 struct fscrypt_mode { 165 const char *friendly_name; 166 const char *cipher_str; 167 int keysize; 168 int ivsize; 169 bool logged_impl_name; 170 bool needs_essiv; 171 }; 172 173 extern void __exit fscrypt_essiv_cleanup(void); 174 175 #endif /* _FSCRYPT_PRIVATE_H */ 176