1 /* 2 * linux/fs/ext4/ext4_crypto.h 3 * 4 * Copyright (C) 2015, Google, Inc. 5 * 6 * This contains encryption header content for ext4 7 * 8 * Written by Michael Halcrow, 2015. 9 */ 10 11 #ifndef _EXT4_CRYPTO_H 12 #define _EXT4_CRYPTO_H 13 14 #include <linux/fs.h> 15 16 #define EXT4_KEY_DESCRIPTOR_SIZE 8 17 18 /* Policy provided via an ioctl on the topmost directory */ 19 struct ext4_encryption_policy { 20 char version; 21 char contents_encryption_mode; 22 char filenames_encryption_mode; 23 char flags; 24 char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE]; 25 } __attribute__((__packed__)); 26 27 #define EXT4_ENCRYPTION_CONTEXT_FORMAT_V1 1 28 #define EXT4_KEY_DERIVATION_NONCE_SIZE 16 29 30 #define EXT4_POLICY_FLAGS_PAD_4 0x00 31 #define EXT4_POLICY_FLAGS_PAD_8 0x01 32 #define EXT4_POLICY_FLAGS_PAD_16 0x02 33 #define EXT4_POLICY_FLAGS_PAD_32 0x03 34 #define EXT4_POLICY_FLAGS_PAD_MASK 0x03 35 #define EXT4_POLICY_FLAGS_VALID 0x03 36 37 /** 38 * Encryption context for inode 39 * 40 * Protector format: 41 * 1 byte: Protector format (1 = this version) 42 * 1 byte: File contents encryption mode 43 * 1 byte: File names encryption mode 44 * 1 byte: Reserved 45 * 8 bytes: Master Key descriptor 46 * 16 bytes: Encryption Key derivation nonce 47 */ 48 struct ext4_encryption_context { 49 char format; 50 char contents_encryption_mode; 51 char filenames_encryption_mode; 52 char flags; 53 char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE]; 54 char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE]; 55 } __attribute__((__packed__)); 56 57 /* Encryption parameters */ 58 #define EXT4_XTS_TWEAK_SIZE 16 59 #define EXT4_AES_128_ECB_KEY_SIZE 16 60 #define EXT4_AES_256_GCM_KEY_SIZE 32 61 #define EXT4_AES_256_CBC_KEY_SIZE 32 62 #define EXT4_AES_256_CTS_KEY_SIZE 32 63 #define EXT4_AES_256_XTS_KEY_SIZE 64 64 #define EXT4_MAX_KEY_SIZE 64 65 66 #define EXT4_KEY_DESC_PREFIX "ext4:" 67 #define EXT4_KEY_DESC_PREFIX_SIZE 5 68 69 struct ext4_encryption_key { 70 uint32_t mode; 71 char raw[EXT4_MAX_KEY_SIZE]; 72 uint32_t size; 73 }; 74 75 #define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 76 #define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL 0x00000002 77 78 struct ext4_crypto_ctx { 79 struct crypto_tfm *tfm; /* Crypto API context */ 80 struct page *bounce_page; /* Ciphertext page on write path */ 81 struct page *control_page; /* Original page on write path */ 82 struct bio *bio; /* The bio for this context */ 83 struct work_struct work; /* Work queue for read complete path */ 84 struct list_head free_list; /* Free list */ 85 int flags; /* Flags */ 86 int mode; /* Encryption mode for tfm */ 87 }; 88 89 struct ext4_completion_result { 90 struct completion completion; 91 int res; 92 }; 93 94 #define DECLARE_EXT4_COMPLETION_RESULT(ecr) \ 95 struct ext4_completion_result ecr = { \ 96 COMPLETION_INITIALIZER((ecr).completion), 0 } 97 ext4_encryption_key_size(int mode)98static inline int ext4_encryption_key_size(int mode) 99 { 100 switch (mode) { 101 case EXT4_ENCRYPTION_MODE_AES_256_XTS: 102 return EXT4_AES_256_XTS_KEY_SIZE; 103 case EXT4_ENCRYPTION_MODE_AES_256_GCM: 104 return EXT4_AES_256_GCM_KEY_SIZE; 105 case EXT4_ENCRYPTION_MODE_AES_256_CBC: 106 return EXT4_AES_256_CBC_KEY_SIZE; 107 case EXT4_ENCRYPTION_MODE_AES_256_CTS: 108 return EXT4_AES_256_CTS_KEY_SIZE; 109 default: 110 BUG(); 111 } 112 return 0; 113 } 114 115 #define EXT4_FNAME_NUM_SCATTER_ENTRIES 4 116 #define EXT4_CRYPTO_BLOCK_SIZE 16 117 #define EXT4_FNAME_CRYPTO_DIGEST_SIZE 32 118 119 struct ext4_str { 120 unsigned char *name; 121 u32 len; 122 }; 123 124 struct ext4_fname_crypto_ctx { 125 u32 lim; 126 char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE]; 127 struct crypto_ablkcipher *ctfm; 128 struct crypto_hash *htfm; 129 struct page *workpage; 130 struct ext4_encryption_key key; 131 unsigned flags : 8; 132 unsigned has_valid_key : 1; 133 unsigned ctfm_key_is_ready : 1; 134 }; 135 136 /** 137 * For encrypted symlinks, the ciphertext length is stored at the beginning 138 * of the string in little-endian format. 139 */ 140 struct ext4_encrypted_symlink_data { 141 __le16 len; 142 char encrypted_path[1]; 143 } __attribute__((__packed__)); 144 145 /** 146 * This function is used to calculate the disk space required to 147 * store a filename of length l in encrypted symlink format. 148 */ encrypted_symlink_data_len(u32 l)149static inline u32 encrypted_symlink_data_len(u32 l) 150 { 151 if (l < EXT4_CRYPTO_BLOCK_SIZE) 152 l = EXT4_CRYPTO_BLOCK_SIZE; 153 return (l + sizeof(struct ext4_encrypted_symlink_data) - 1); 154 } 155 156 #endif /* _EXT4_CRYPTO_H */ 157