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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * fs-verity: read-only file-based authenticity protection4 *5 * Copyright 2019 Google LLC6 */7 8#ifndef _FSVERITY_PRIVATE_H9#define _FSVERITY_PRIVATE_H10 11#define pr_fmt(fmt) "fs-verity: " fmt12 13#include <linux/fsverity.h>14 15/*16 * Implementation limit: maximum depth of the Merkle tree. For now 8 is plenty;17 * it's enough for over U64_MAX bytes of data using SHA-256 and 4K blocks.18 */19#define FS_VERITY_MAX_LEVELS 820 21/* A hash algorithm supported by fs-verity */22struct fsverity_hash_alg {23 struct crypto_shash *tfm; /* hash tfm, allocated on demand */24 const char *name; /* crypto API name, e.g. sha256 */25 unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */26 unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */27 /*28 * The HASH_ALGO_* constant for this algorithm. This is different from29 * FS_VERITY_HASH_ALG_*, which uses a different numbering scheme.30 */31 enum hash_algo algo_id;32};33 34/* Merkle tree parameters: hash algorithm, initial hash state, and topology */35struct merkle_tree_params {36 const struct fsverity_hash_alg *hash_alg; /* the hash algorithm */37 const u8 *hashstate; /* initial hash state or NULL */38 unsigned int digest_size; /* same as hash_alg->digest_size */39 unsigned int block_size; /* size of data and tree blocks */40 unsigned int hashes_per_block; /* number of hashes per tree block */41 unsigned int blocks_per_page; /* PAGE_SIZE / block_size */42 u8 log_digestsize; /* log2(digest_size) */43 u8 log_blocksize; /* log2(block_size) */44 u8 log_arity; /* log2(hashes_per_block) */45 u8 log_blocks_per_page; /* log2(blocks_per_page) */46 unsigned int num_levels; /* number of levels in Merkle tree */47 u64 tree_size; /* Merkle tree size in bytes */48 unsigned long tree_pages; /* Merkle tree size in pages */49 50 /*51 * Starting block index for each tree level, ordered from leaf level (0)52 * to root level ('num_levels - 1')53 */54 unsigned long level_start[FS_VERITY_MAX_LEVELS];55};56 57/*58 * fsverity_info - cached verity metadata for an inode59 *60 * When a verity file is first opened, an instance of this struct is allocated61 * and stored in ->i_verity_info; it remains until the inode is evicted. It62 * caches information about the Merkle tree that's needed to efficiently verify63 * data read from the file. It also caches the file digest. The Merkle tree64 * pages themselves are not cached here, but the filesystem may cache them.65 */66struct fsverity_info {67 struct merkle_tree_params tree_params;68 u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE];69 u8 file_digest[FS_VERITY_MAX_DIGEST_SIZE];70 const struct inode *inode;71 unsigned long *hash_block_verified;72};73 74#define FS_VERITY_MAX_SIGNATURE_SIZE (FS_VERITY_MAX_DESCRIPTOR_SIZE - \75 sizeof(struct fsverity_descriptor))76 77/* hash_algs.c */78 79extern struct fsverity_hash_alg fsverity_hash_algs[];80 81const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,82 unsigned int num);83const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg,84 const u8 *salt, size_t salt_size);85int fsverity_hash_block(const struct merkle_tree_params *params,86 const struct inode *inode, const void *data, u8 *out);87int fsverity_hash_buffer(const struct fsverity_hash_alg *alg,88 const void *data, size_t size, u8 *out);89void __init fsverity_check_hash_algs(void);90 91/* init.c */92 93void __printf(3, 4) __cold94fsverity_msg(const struct inode *inode, const char *level,95 const char *fmt, ...);96 97#define fsverity_warn(inode, fmt, ...) \98 fsverity_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)99#define fsverity_err(inode, fmt, ...) \100 fsverity_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)101 102/* measure.c */103 104#ifdef CONFIG_BPF_SYSCALL105void __init fsverity_init_bpf(void);106#else107static inline void fsverity_init_bpf(void)108{109}110#endif111 112/* open.c */113 114int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,115 const struct inode *inode,116 unsigned int hash_algorithm,117 unsigned int log_blocksize,118 const u8 *salt, size_t salt_size);119 120struct fsverity_info *fsverity_create_info(const struct inode *inode,121 struct fsverity_descriptor *desc);122 123void fsverity_set_info(struct inode *inode, struct fsverity_info *vi);124 125void fsverity_free_info(struct fsverity_info *vi);126 127int fsverity_get_descriptor(struct inode *inode,128 struct fsverity_descriptor **desc_ret);129 130void __init fsverity_init_info_cache(void);131 132/* signature.c */133 134#ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES135extern int fsverity_require_signatures;136int fsverity_verify_signature(const struct fsverity_info *vi,137 const u8 *signature, size_t sig_size);138 139void __init fsverity_init_signature(void);140#else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */141static inline int142fsverity_verify_signature(const struct fsverity_info *vi,143 const u8 *signature, size_t sig_size)144{145 return 0;146}147 148static inline void fsverity_init_signature(void)149{150}151#endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */152 153/* verify.c */154 155void __init fsverity_init_workqueue(void);156 157#endif /* _FSVERITY_PRIVATE_H */158