fs/f2fs/f2fs_crypto.h

   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
 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  */
 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 */