186 строки
6.0 KiB
C
186 строки
6.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* fs-verity: read-only file-based authenticity protection
|
|
*
|
|
* Copyright 2019 Google LLC
|
|
*/
|
|
|
|
#ifndef _FSVERITY_PRIVATE_H
|
|
#define _FSVERITY_PRIVATE_H
|
|
|
|
#ifdef CONFIG_FS_VERITY_DEBUG
|
|
#define DEBUG
|
|
#endif
|
|
|
|
#define pr_fmt(fmt) "fs-verity: " fmt
|
|
|
|
#include <crypto/sha.h>
|
|
#include <linux/fsverity.h>
|
|
|
|
struct ahash_request;
|
|
|
|
/*
|
|
* Implementation limit: maximum depth of the Merkle tree. For now 8 is plenty;
|
|
* it's enough for over U64_MAX bytes of data using SHA-256 and 4K blocks.
|
|
*/
|
|
#define FS_VERITY_MAX_LEVELS 8
|
|
|
|
/*
|
|
* Largest digest size among all hash algorithms supported by fs-verity.
|
|
* Currently assumed to be <= size of fsverity_descriptor::root_hash.
|
|
*/
|
|
#define FS_VERITY_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
|
|
|
|
/* A hash algorithm supported by fs-verity */
|
|
struct fsverity_hash_alg {
|
|
struct crypto_ahash *tfm; /* hash tfm, allocated on demand */
|
|
const char *name; /* crypto API name, e.g. sha256 */
|
|
unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */
|
|
unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */
|
|
};
|
|
|
|
/* Merkle tree parameters: hash algorithm, initial hash state, and topology */
|
|
struct merkle_tree_params {
|
|
const struct fsverity_hash_alg *hash_alg; /* the hash algorithm */
|
|
const u8 *hashstate; /* initial hash state or NULL */
|
|
unsigned int digest_size; /* same as hash_alg->digest_size */
|
|
unsigned int block_size; /* size of data and tree blocks */
|
|
unsigned int hashes_per_block; /* number of hashes per tree block */
|
|
unsigned int log_blocksize; /* log2(block_size) */
|
|
unsigned int log_arity; /* log2(hashes_per_block) */
|
|
unsigned int num_levels; /* number of levels in Merkle tree */
|
|
u64 tree_size; /* Merkle tree size in bytes */
|
|
|
|
/*
|
|
* Starting block index for each tree level, ordered from leaf level (0)
|
|
* to root level ('num_levels - 1')
|
|
*/
|
|
u64 level_start[FS_VERITY_MAX_LEVELS];
|
|
};
|
|
|
|
/**
|
|
* fsverity_info - cached verity metadata for an inode
|
|
*
|
|
* When a verity file is first opened, an instance of this struct is allocated
|
|
* and stored in ->i_verity_info; it remains until the inode is evicted. It
|
|
* caches information about the Merkle tree that's needed to efficiently verify
|
|
* data read from the file. It also caches the file measurement. The Merkle
|
|
* tree pages themselves are not cached here, but the filesystem may cache them.
|
|
*/
|
|
struct fsverity_info {
|
|
struct merkle_tree_params tree_params;
|
|
u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE];
|
|
u8 measurement[FS_VERITY_MAX_DIGEST_SIZE];
|
|
const struct inode *inode;
|
|
};
|
|
|
|
/*
|
|
* Merkle tree properties. The file measurement is the hash of this structure
|
|
* excluding the signature and with the sig_size field set to 0.
|
|
*/
|
|
struct fsverity_descriptor {
|
|
__u8 version; /* must be 1 */
|
|
__u8 hash_algorithm; /* Merkle tree hash algorithm */
|
|
__u8 log_blocksize; /* log2 of size of data and tree blocks */
|
|
__u8 salt_size; /* size of salt in bytes; 0 if none */
|
|
__le32 sig_size; /* size of signature in bytes; 0 if none */
|
|
__le64 data_size; /* size of file the Merkle tree is built over */
|
|
__u8 root_hash[64]; /* Merkle tree root hash */
|
|
__u8 salt[32]; /* salt prepended to each hashed block */
|
|
__u8 __reserved[144]; /* must be 0's */
|
|
__u8 signature[]; /* optional PKCS#7 signature */
|
|
};
|
|
|
|
/* Arbitrary limit to bound the kmalloc() size. Can be changed. */
|
|
#define FS_VERITY_MAX_DESCRIPTOR_SIZE 16384
|
|
|
|
#define FS_VERITY_MAX_SIGNATURE_SIZE (FS_VERITY_MAX_DESCRIPTOR_SIZE - \
|
|
sizeof(struct fsverity_descriptor))
|
|
|
|
/*
|
|
* Format in which verity file measurements are signed. This is the same as
|
|
* 'struct fsverity_digest', except here some magic bytes are prepended to
|
|
* provide some context about what is being signed in case the same key is used
|
|
* for non-fsverity purposes, and here the fields have fixed endianness.
|
|
*/
|
|
struct fsverity_signed_digest {
|
|
char magic[8]; /* must be "FSVerity" */
|
|
__le16 digest_algorithm;
|
|
__le16 digest_size;
|
|
__u8 digest[];
|
|
};
|
|
|
|
/* hash_algs.c */
|
|
|
|
extern struct fsverity_hash_alg fsverity_hash_algs[];
|
|
|
|
const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
|
|
unsigned int num);
|
|
const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg,
|
|
const u8 *salt, size_t salt_size);
|
|
int fsverity_hash_page(const struct merkle_tree_params *params,
|
|
const struct inode *inode,
|
|
struct ahash_request *req, struct page *page, u8 *out);
|
|
int fsverity_hash_buffer(const struct fsverity_hash_alg *alg,
|
|
const void *data, size_t size, u8 *out);
|
|
void __init fsverity_check_hash_algs(void);
|
|
|
|
/* init.c */
|
|
|
|
extern void __printf(3, 4) __cold
|
|
fsverity_msg(const struct inode *inode, const char *level,
|
|
const char *fmt, ...);
|
|
|
|
#define fsverity_warn(inode, fmt, ...) \
|
|
fsverity_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
|
|
#define fsverity_err(inode, fmt, ...) \
|
|
fsverity_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
|
|
|
|
/* open.c */
|
|
|
|
int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,
|
|
const struct inode *inode,
|
|
unsigned int hash_algorithm,
|
|
unsigned int log_blocksize,
|
|
const u8 *salt, size_t salt_size);
|
|
|
|
struct fsverity_info *fsverity_create_info(const struct inode *inode,
|
|
void *desc, size_t desc_size);
|
|
|
|
void fsverity_set_info(struct inode *inode, struct fsverity_info *vi);
|
|
|
|
void fsverity_free_info(struct fsverity_info *vi);
|
|
|
|
int __init fsverity_init_info_cache(void);
|
|
void __init fsverity_exit_info_cache(void);
|
|
|
|
/* signature.c */
|
|
|
|
#ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES
|
|
int fsverity_verify_signature(const struct fsverity_info *vi,
|
|
const struct fsverity_descriptor *desc,
|
|
size_t desc_size);
|
|
|
|
int __init fsverity_init_signature(void);
|
|
#else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */
|
|
static inline int
|
|
fsverity_verify_signature(const struct fsverity_info *vi,
|
|
const struct fsverity_descriptor *desc,
|
|
size_t desc_size)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int fsverity_init_signature(void)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */
|
|
|
|
/* verify.c */
|
|
|
|
int __init fsverity_init_workqueue(void);
|
|
void __init fsverity_exit_workqueue(void);
|
|
|
|
#endif /* _FSVERITY_PRIVATE_H */
|