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>
14671e67b4SEric Biggers
15671e67b4SEric Biggers /*
16671e67b4SEric Biggers * Implementation limit: maximum depth of the Merkle tree. For now 8 is plenty;
17671e67b4SEric Biggers * it's enough for over U64_MAX bytes of data using SHA-256 and 4K blocks.
18671e67b4SEric Biggers */
19671e67b4SEric Biggers #define FS_VERITY_MAX_LEVELS 8
20671e67b4SEric Biggers
21671e67b4SEric Biggers /* A hash algorithm supported by fs-verity */
22671e67b4SEric Biggers struct fsverity_hash_alg {
238fcd94adSEric Biggers struct crypto_shash *tfm; /* hash tfm, allocated on demand */
24671e67b4SEric Biggers const char *name; /* crypto API name, e.g. sha256 */
25671e67b4SEric Biggers unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */
26671e67b4SEric Biggers unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */
27a4bbf53dSEric Biggers /*
28a4bbf53dSEric Biggers * The HASH_ALGO_* constant for this algorithm. This is different from
29a4bbf53dSEric Biggers * FS_VERITY_HASH_ALG_*, which uses a different numbering scheme.
30a4bbf53dSEric Biggers */
31a4bbf53dSEric Biggers enum hash_algo algo_id;
32671e67b4SEric Biggers };
33671e67b4SEric Biggers
34671e67b4SEric Biggers /* Merkle tree parameters: hash algorithm, initial hash state, and topology */
35671e67b4SEric Biggers struct merkle_tree_params {
3632ab3c5eSEric Biggers const struct fsverity_hash_alg *hash_alg; /* the hash algorithm */
37671e67b4SEric Biggers const u8 *hashstate; /* initial hash state or NULL */
38671e67b4SEric Biggers unsigned int digest_size; /* same as hash_alg->digest_size */
39671e67b4SEric Biggers unsigned int block_size; /* size of data and tree blocks */
40671e67b4SEric Biggers unsigned int hashes_per_block; /* number of hashes per tree block */
415306892aSEric Biggers unsigned int blocks_per_page; /* PAGE_SIZE / block_size */
42579a12f7SEric Biggers u8 log_digestsize; /* log2(digest_size) */
43579a12f7SEric Biggers u8 log_blocksize; /* log2(block_size) */
44579a12f7SEric Biggers u8 log_arity; /* log2(hashes_per_block) */
455306892aSEric Biggers u8 log_blocks_per_page; /* log2(blocks_per_page) */
46671e67b4SEric Biggers unsigned int num_levels; /* number of levels in Merkle tree */
47671e67b4SEric Biggers u64 tree_size; /* Merkle tree size in bytes */
489098f36bSEric Biggers unsigned long tree_pages; /* Merkle tree size in pages */
49671e67b4SEric Biggers
50671e67b4SEric Biggers /*
51671e67b4SEric Biggers * Starting block index for each tree level, ordered from leaf level (0)
52671e67b4SEric Biggers * to root level ('num_levels - 1')
53671e67b4SEric Biggers */
54284d5db5SEric Biggers unsigned long level_start[FS_VERITY_MAX_LEVELS];
55671e67b4SEric Biggers };
56671e67b4SEric Biggers
576377a38bSEric Biggers /*
58fd2d1acfSEric Biggers * fsverity_info - cached verity metadata for an inode
59fd2d1acfSEric Biggers *
60fd2d1acfSEric Biggers * When a verity file is first opened, an instance of this struct is allocated
61fd2d1acfSEric Biggers * and stored in ->i_verity_info; it remains until the inode is evicted. It
62fd2d1acfSEric Biggers * caches information about the Merkle tree that's needed to efficiently verify
63ed45e201SEric Biggers * data read from the file. It also caches the file digest. The Merkle tree
64ed45e201SEric Biggers * pages themselves are not cached here, but the filesystem may cache them.
65fd2d1acfSEric Biggers */
66fd2d1acfSEric Biggers struct fsverity_info {
67fd2d1acfSEric Biggers struct merkle_tree_params tree_params;
68fd2d1acfSEric Biggers u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE];
69ed45e201SEric Biggers u8 file_digest[FS_VERITY_MAX_DIGEST_SIZE];
70fd2d1acfSEric Biggers const struct inode *inode;
715306892aSEric Biggers unsigned long *hash_block_verified;
725306892aSEric Biggers spinlock_t hash_page_init_lock;
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
8232ab3c5eSEric Biggers const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
83671e67b4SEric Biggers unsigned int num);
8432ab3c5eSEric Biggers const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg,
85671e67b4SEric Biggers const u8 *salt, size_t salt_size);
86f45555bfSEric Biggers int fsverity_hash_block(const struct merkle_tree_params *params,
878fcd94adSEric Biggers const struct inode *inode, const void *data, u8 *out);
8832ab3c5eSEric Biggers int fsverity_hash_buffer(const struct fsverity_hash_alg *alg,
89671e67b4SEric Biggers const void *data, size_t size, u8 *out);
90671e67b4SEric Biggers void __init fsverity_check_hash_algs(void);
91671e67b4SEric Biggers
92671e67b4SEric Biggers /* init.c */
93671e67b4SEric Biggers
949cd6b593SEric Biggers void __printf(3, 4) __cold
95671e67b4SEric Biggers fsverity_msg(const struct inode *inode, const char *level,
96671e67b4SEric Biggers const char *fmt, ...);
97671e67b4SEric Biggers
98671e67b4SEric Biggers #define fsverity_warn(inode, fmt, ...) \
99671e67b4SEric Biggers fsverity_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
100671e67b4SEric Biggers #define fsverity_err(inode, fmt, ...) \
101671e67b4SEric Biggers fsverity_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
102671e67b4SEric Biggers
103fd2d1acfSEric Biggers /* open.c */
104fd2d1acfSEric Biggers
105fd2d1acfSEric Biggers int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,
106fd2d1acfSEric Biggers const struct inode *inode,
107fd2d1acfSEric Biggers unsigned int hash_algorithm,
108fd2d1acfSEric Biggers unsigned int log_blocksize,
109fd2d1acfSEric Biggers const u8 *salt, size_t salt_size);
110fd2d1acfSEric Biggers
111fd2d1acfSEric Biggers struct fsverity_info *fsverity_create_info(const struct inode *inode,
112b0487edeSZhang Jianhua struct fsverity_descriptor *desc);
113fd2d1acfSEric Biggers
114fd2d1acfSEric Biggers void fsverity_set_info(struct inode *inode, struct fsverity_info *vi);
115fd2d1acfSEric Biggers
116fd2d1acfSEric Biggers void fsverity_free_info(struct fsverity_info *vi);
117fd2d1acfSEric Biggers
118c2c82611SEric Biggers int fsverity_get_descriptor(struct inode *inode,
119b0487edeSZhang Jianhua struct fsverity_descriptor **desc_ret);
120c2c82611SEric Biggers
121e77000ccSEric Biggers void __init fsverity_init_info_cache(void);
1228a1d0f9cSEric Biggers
123432434c9SEric Biggers /* signature.c */
124432434c9SEric Biggers
125432434c9SEric Biggers #ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES
126*456ae5feSEric Biggers extern int fsverity_require_signatures;
127432434c9SEric Biggers int fsverity_verify_signature(const struct fsverity_info *vi,
128fab634c4SEric Biggers const u8 *signature, size_t sig_size);
129432434c9SEric Biggers
130e77000ccSEric Biggers void __init fsverity_init_signature(void);
131432434c9SEric Biggers #else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */
132432434c9SEric Biggers static inline int
fsverity_verify_signature(const struct fsverity_info * vi,const u8 * signature,size_t sig_size)133432434c9SEric Biggers fsverity_verify_signature(const struct fsverity_info *vi,
134fab634c4SEric Biggers const u8 *signature, size_t sig_size)
135432434c9SEric Biggers {
136432434c9SEric Biggers return 0;
137432434c9SEric Biggers }
138432434c9SEric Biggers
fsverity_init_signature(void)139e77000ccSEric Biggers static inline void fsverity_init_signature(void)
140432434c9SEric Biggers {
141432434c9SEric Biggers }
142432434c9SEric Biggers #endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */
143432434c9SEric Biggers
1448a1d0f9cSEric Biggers /* verify.c */
1458a1d0f9cSEric Biggers
146e77000ccSEric Biggers void __init fsverity_init_workqueue(void);
147fd2d1acfSEric Biggers
148671e67b4SEric Biggers #endif /* _FSVERITY_PRIVATE_H */
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