1671e67b4SEric Biggers /* SPDX-License-Identifier: GPL-2.0 */ 2671e67b4SEric Biggers /* 3671e67b4SEric Biggers * fs-verity: read-only file-based authenticity protection 4671e67b4SEric Biggers * 5671e67b4SEric Biggers * Copyright 2019 Google LLC 6671e67b4SEric Biggers */ 7671e67b4SEric Biggers 8671e67b4SEric Biggers #ifndef _FSVERITY_PRIVATE_H 9671e67b4SEric Biggers #define _FSVERITY_PRIVATE_H 10671e67b4SEric Biggers 11671e67b4SEric Biggers #define pr_fmt(fmt) "fs-verity: " fmt 12671e67b4SEric Biggers 13fd2d1acfSEric Biggers #include <linux/fsverity.h> 14439bea10SEric Biggers #include <linux/mempool.h> 15671e67b4SEric Biggers 16671e67b4SEric Biggers struct ahash_request; 17671e67b4SEric Biggers 18671e67b4SEric Biggers /* 19671e67b4SEric Biggers * Implementation limit: maximum depth of the Merkle tree. For now 8 is plenty; 20671e67b4SEric Biggers * it's enough for over U64_MAX bytes of data using SHA-256 and 4K blocks. 21671e67b4SEric Biggers */ 22671e67b4SEric Biggers #define FS_VERITY_MAX_LEVELS 8 23671e67b4SEric Biggers 24671e67b4SEric Biggers /* A hash algorithm supported by fs-verity */ 25671e67b4SEric Biggers struct fsverity_hash_alg { 26671e67b4SEric Biggers struct crypto_ahash *tfm; /* hash tfm, allocated on demand */ 27671e67b4SEric Biggers const char *name; /* crypto API name, e.g. sha256 */ 28671e67b4SEric Biggers unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */ 29671e67b4SEric Biggers unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */ 30439bea10SEric Biggers mempool_t req_pool; /* mempool with a preallocated hash request */ 31a4bbf53dSEric Biggers /* 32a4bbf53dSEric Biggers * The HASH_ALGO_* constant for this algorithm. This is different from 33a4bbf53dSEric Biggers * FS_VERITY_HASH_ALG_*, which uses a different numbering scheme. 34a4bbf53dSEric Biggers */ 35a4bbf53dSEric Biggers enum hash_algo algo_id; 36671e67b4SEric Biggers }; 37671e67b4SEric Biggers 38671e67b4SEric Biggers /* Merkle tree parameters: hash algorithm, initial hash state, and topology */ 39671e67b4SEric Biggers struct merkle_tree_params { 40439bea10SEric Biggers struct fsverity_hash_alg *hash_alg; /* the hash algorithm */ 41671e67b4SEric Biggers const u8 *hashstate; /* initial hash state or NULL */ 42671e67b4SEric Biggers unsigned int digest_size; /* same as hash_alg->digest_size */ 43671e67b4SEric Biggers unsigned int block_size; /* size of data and tree blocks */ 44671e67b4SEric Biggers unsigned int hashes_per_block; /* number of hashes per tree block */ 45671e67b4SEric Biggers unsigned int log_blocksize; /* log2(block_size) */ 46671e67b4SEric Biggers unsigned int log_arity; /* log2(hashes_per_block) */ 47671e67b4SEric Biggers unsigned int num_levels; /* number of levels in Merkle tree */ 48671e67b4SEric Biggers u64 tree_size; /* Merkle tree size in bytes */ 49*9098f36bSEric Biggers unsigned long tree_pages; /* Merkle tree size in pages */ 50671e67b4SEric Biggers 51671e67b4SEric Biggers /* 52671e67b4SEric Biggers * Starting block index for each tree level, ordered from leaf level (0) 53671e67b4SEric Biggers * to root level ('num_levels - 1') 54671e67b4SEric Biggers */ 55284d5db5SEric Biggers unsigned long level_start[FS_VERITY_MAX_LEVELS]; 56671e67b4SEric Biggers }; 57671e67b4SEric Biggers 586377a38bSEric Biggers /* 59fd2d1acfSEric Biggers * fsverity_info - cached verity metadata for an inode 60fd2d1acfSEric Biggers * 61fd2d1acfSEric Biggers * When a verity file is first opened, an instance of this struct is allocated 62fd2d1acfSEric Biggers * and stored in ->i_verity_info; it remains until the inode is evicted. It 63fd2d1acfSEric Biggers * caches information about the Merkle tree that's needed to efficiently verify 64ed45e201SEric Biggers * data read from the file. It also caches the file digest. The Merkle tree 65ed45e201SEric Biggers * pages themselves are not cached here, but the filesystem may cache them. 66fd2d1acfSEric Biggers */ 67fd2d1acfSEric Biggers struct fsverity_info { 68fd2d1acfSEric Biggers struct merkle_tree_params tree_params; 69fd2d1acfSEric Biggers u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE]; 70ed45e201SEric Biggers u8 file_digest[FS_VERITY_MAX_DIGEST_SIZE]; 71fd2d1acfSEric Biggers const struct inode *inode; 72fd2d1acfSEric Biggers }; 73fd2d1acfSEric Biggers 74fd2d1acfSEric Biggers 75432434c9SEric Biggers #define FS_VERITY_MAX_SIGNATURE_SIZE (FS_VERITY_MAX_DESCRIPTOR_SIZE - \ 76432434c9SEric Biggers sizeof(struct fsverity_descriptor)) 77432434c9SEric Biggers 78671e67b4SEric Biggers /* hash_algs.c */ 79671e67b4SEric Biggers 80671e67b4SEric Biggers extern struct fsverity_hash_alg fsverity_hash_algs[]; 81671e67b4SEric Biggers 82439bea10SEric Biggers struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, 83671e67b4SEric Biggers unsigned int num); 84439bea10SEric Biggers struct ahash_request *fsverity_alloc_hash_request(struct fsverity_hash_alg *alg, 85439bea10SEric Biggers gfp_t gfp_flags); 86439bea10SEric Biggers void fsverity_free_hash_request(struct fsverity_hash_alg *alg, 87439bea10SEric Biggers struct ahash_request *req); 88439bea10SEric Biggers const u8 *fsverity_prepare_hash_state(struct fsverity_hash_alg *alg, 89671e67b4SEric Biggers const u8 *salt, size_t salt_size); 90671e67b4SEric Biggers int fsverity_hash_page(const struct merkle_tree_params *params, 91671e67b4SEric Biggers const struct inode *inode, 92671e67b4SEric Biggers struct ahash_request *req, struct page *page, u8 *out); 93439bea10SEric Biggers int fsverity_hash_buffer(struct fsverity_hash_alg *alg, 94671e67b4SEric Biggers const void *data, size_t size, u8 *out); 95671e67b4SEric Biggers void __init fsverity_check_hash_algs(void); 96671e67b4SEric Biggers 97671e67b4SEric Biggers /* init.c */ 98671e67b4SEric Biggers 999cd6b593SEric Biggers void __printf(3, 4) __cold 100671e67b4SEric Biggers fsverity_msg(const struct inode *inode, const char *level, 101671e67b4SEric Biggers const char *fmt, ...); 102671e67b4SEric Biggers 103671e67b4SEric Biggers #define fsverity_warn(inode, fmt, ...) \ 104671e67b4SEric Biggers fsverity_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__) 105671e67b4SEric Biggers #define fsverity_err(inode, fmt, ...) \ 106671e67b4SEric Biggers fsverity_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__) 107671e67b4SEric Biggers 108fd2d1acfSEric Biggers /* open.c */ 109fd2d1acfSEric Biggers 110fd2d1acfSEric Biggers int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, 111fd2d1acfSEric Biggers const struct inode *inode, 112fd2d1acfSEric Biggers unsigned int hash_algorithm, 113fd2d1acfSEric Biggers unsigned int log_blocksize, 114fd2d1acfSEric Biggers const u8 *salt, size_t salt_size); 115fd2d1acfSEric Biggers 116fd2d1acfSEric Biggers struct fsverity_info *fsverity_create_info(const struct inode *inode, 117b0487edeSZhang Jianhua struct fsverity_descriptor *desc); 118fd2d1acfSEric Biggers 119fd2d1acfSEric Biggers void fsverity_set_info(struct inode *inode, struct fsverity_info *vi); 120fd2d1acfSEric Biggers 121fd2d1acfSEric Biggers void fsverity_free_info(struct fsverity_info *vi); 122fd2d1acfSEric Biggers 123c2c82611SEric Biggers int fsverity_get_descriptor(struct inode *inode, 124b0487edeSZhang Jianhua struct fsverity_descriptor **desc_ret); 125c2c82611SEric Biggers 126fd2d1acfSEric Biggers int __init fsverity_init_info_cache(void); 1278a1d0f9cSEric Biggers void __init fsverity_exit_info_cache(void); 1288a1d0f9cSEric Biggers 129432434c9SEric Biggers /* signature.c */ 130432434c9SEric Biggers 131432434c9SEric Biggers #ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES 132432434c9SEric Biggers int fsverity_verify_signature(const struct fsverity_info *vi, 133fab634c4SEric Biggers const u8 *signature, size_t sig_size); 134432434c9SEric Biggers 135432434c9SEric Biggers int __init fsverity_init_signature(void); 136432434c9SEric Biggers #else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ 137432434c9SEric Biggers static inline int 138432434c9SEric Biggers fsverity_verify_signature(const struct fsverity_info *vi, 139fab634c4SEric Biggers const u8 *signature, size_t sig_size) 140432434c9SEric Biggers { 141432434c9SEric Biggers return 0; 142432434c9SEric Biggers } 143432434c9SEric Biggers 144432434c9SEric Biggers static inline int fsverity_init_signature(void) 145432434c9SEric Biggers { 146432434c9SEric Biggers return 0; 147432434c9SEric Biggers } 148432434c9SEric Biggers #endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ 149432434c9SEric Biggers 1508a1d0f9cSEric Biggers /* verify.c */ 1518a1d0f9cSEric Biggers 1528a1d0f9cSEric Biggers int __init fsverity_init_workqueue(void); 153432434c9SEric Biggers void __init fsverity_exit_workqueue(void); 154fd2d1acfSEric Biggers 155671e67b4SEric Biggers #endif /* _FSVERITY_PRIVATE_H */ 156