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 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