linux/fs/verity/fsverity_private.h

/* 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

#define pr_fmt(fmt) …

#include <linux/fsverity.h>

/*
 * 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 …

/* A hash algorithm supported by fs-verity */
struct fsverity_hash_alg { … };

/* Merkle tree parameters: hash algorithm, initial hash state, and topology */
struct merkle_tree_params { … };

/*
 * 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 digest.  The Merkle tree
 * pages themselves are not cached here, but the filesystem may cache them.
 */
struct fsverity_info { … };

#define FS_VERITY_MAX_SIGNATURE_SIZE …

/* 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_block(const struct merkle_tree_params *params,
			const struct inode *inode, const void *data, 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 */

void __printf(3, 4) __cold
fsverity_msg(const struct inode *inode, const char *level,
	     const char *fmt, ...);

#define fsverity_warn(inode, fmt, ...) …
#define fsverity_err(inode, fmt, ...) …

/* measure.c */

#ifdef CONFIG_BPF_SYSCALL
void __init fsverity_init_bpf(void);
#else
static inline void fsverity_init_bpf(void)
{
}
#endif

/* 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,
					   struct fsverity_descriptor *desc);

void fsverity_set_info(struct inode *inode, struct fsverity_info *vi);

void fsverity_free_info(struct fsverity_info *vi);

int fsverity_get_descriptor(struct inode *inode,
			    struct fsverity_descriptor **desc_ret);

void __init fsverity_init_info_cache(void);

/* signature.c */

#ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES
extern int fsverity_require_signatures;
int fsverity_verify_signature(const struct fsverity_info *vi,
			      const u8 *signature, size_t sig_size);

void __init fsverity_init_signature(void);
#else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */
static inline int
fsverity_verify_signature(const struct fsverity_info *vi,
			  const u8 *signature, size_t sig_size)
{
	return 0;
}

static inline void fsverity_init_signature(void)
{
}
#endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */

/* verify.c */

void __init fsverity_init_workqueue(void);

#endif /* _FSVERITY_PRIVATE_H */