1 files changed, 88 insertions, 0 deletions
diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
new file mode 100644
index 000000000000..9697aaebb5dc
--- /dev/null
+++ b/fs/verity/fsverity_private.h
@@ -0,0 +1,88 @@
+/* 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/fs.h>
+#include <uapi/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	SHA256_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];
+};
+
+/* 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__)
+
+#endif /* _FSVERITY_PRIVATE_H */