1 /* 2 * Copyright (C) 2012 Red Hat, Inc. 3 * Copyright (C) 2015 Google, Inc. 4 * 5 * Author: Mikulas Patocka <mpatocka@redhat.com> 6 * 7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors 8 * 9 * This file is released under the GPLv2. 10 */ 11 12 #ifndef DM_VERITY_H 13 #define DM_VERITY_H 14 15 #include "dm-bufio.h" 16 #include <linux/device-mapper.h> 17 #include <crypto/hash.h> 18 19 #define DM_VERITY_MAX_LEVELS 63 20 21 enum verity_mode { 22 DM_VERITY_MODE_EIO, 23 DM_VERITY_MODE_LOGGING, 24 DM_VERITY_MODE_RESTART 25 }; 26 27 enum verity_block_type { 28 DM_VERITY_BLOCK_TYPE_DATA, 29 DM_VERITY_BLOCK_TYPE_METADATA 30 }; 31 32 struct dm_verity_fec; 33 34 struct dm_verity { 35 struct dm_dev *data_dev; 36 struct dm_dev *hash_dev; 37 struct dm_target *ti; 38 struct dm_bufio_client *bufio; 39 char *alg_name; 40 struct crypto_shash *tfm; 41 u8 *root_digest; /* digest of the root block */ 42 u8 *salt; /* salt: its size is salt_size */ 43 u8 *zero_digest; /* digest for a zero block */ 44 unsigned salt_size; 45 sector_t data_start; /* data offset in 512-byte sectors */ 46 sector_t hash_start; /* hash start in blocks */ 47 sector_t data_blocks; /* the number of data blocks */ 48 sector_t hash_blocks; /* the number of hash blocks */ 49 unsigned char data_dev_block_bits; /* log2(data blocksize) */ 50 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */ 51 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */ 52 unsigned char levels; /* the number of tree levels */ 53 unsigned char version; 54 unsigned digest_size; /* digest size for the current hash algorithm */ 55 unsigned shash_descsize;/* the size of temporary space for crypto */ 56 int hash_failed; /* set to 1 if hash of any block failed */ 57 enum verity_mode mode; /* mode for handling verification errors */ 58 unsigned corrupted_errs;/* Number of errors for corrupted blocks */ 59 60 struct workqueue_struct *verify_wq; 61 62 /* starting blocks for each tree level. 0 is the lowest level. */ 63 sector_t hash_level_block[DM_VERITY_MAX_LEVELS]; 64 65 struct dm_verity_fec *fec; /* forward error correction */ 66 }; 67 68 struct dm_verity_io { 69 struct dm_verity *v; 70 71 /* original value of bio->bi_end_io */ 72 bio_end_io_t *orig_bi_end_io; 73 74 sector_t block; 75 unsigned n_blocks; 76 77 struct bvec_iter iter; 78 79 struct work_struct work; 80 81 /* 82 * Three variably-size fields follow this struct: 83 * 84 * u8 hash_desc[v->shash_descsize]; 85 * u8 real_digest[v->digest_size]; 86 * u8 want_digest[v->digest_size]; 87 * 88 * To access them use: verity_io_hash_desc(), verity_io_real_digest() 89 * and verity_io_want_digest(). 90 */ 91 }; 92 93 static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v, 94 struct dm_verity_io *io) 95 { 96 return (struct shash_desc *)(io + 1); 97 } 98 99 static inline u8 *verity_io_real_digest(struct dm_verity *v, 100 struct dm_verity_io *io) 101 { 102 return (u8 *)(io + 1) + v->shash_descsize; 103 } 104 105 static inline u8 *verity_io_want_digest(struct dm_verity *v, 106 struct dm_verity_io *io) 107 { 108 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size; 109 } 110 111 static inline u8 *verity_io_digest_end(struct dm_verity *v, 112 struct dm_verity_io *io) 113 { 114 return verity_io_want_digest(v, io) + v->digest_size; 115 } 116 117 extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 118 struct bvec_iter *iter, 119 int (*process)(struct dm_verity *v, 120 struct dm_verity_io *io, 121 u8 *data, size_t len)); 122 123 extern int verity_hash(struct dm_verity *v, struct shash_desc *desc, 124 const u8 *data, size_t len, u8 *digest); 125 126 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 127 sector_t block, u8 *digest, bool *is_zero); 128 129 #endif /* DM_VERITY_H */ 130