Upgrade to latest fsverity_uapi.h

The latest UAPI header includes the declarations of fsverity_descriptor
and fsverity_formatted_digest (previously fsverity_signed_digest).
Therefore they no longer need to be declared in other files.

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113213314.73616-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

common/fsverity_uapi.h

@@ -34,6 +34,55 @@ struct fsverity_digest {
 	__u8 digest[];
 };
 
+/*
+ * Struct containing a file's Merkle tree properties.  The fs-verity file digest
+ * is the hash of this struct.  A userspace program needs this struct only if it
+ * needs to compute fs-verity file digests itself, e.g. in order to sign files.
+ * It isn't needed just to enable fs-verity on a file.
+ *
+ * Note: when computing the file digest, 'sig_size' and 'signature' must be left
+ * zero and empty, respectively.  These fields are present only because some
+ * filesystems reuse this struct as part of their on-disk format.
+ */
+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 */
+#ifdef __KERNEL__
+	__le32 sig_size;
+#else
+	__le32 __reserved_0x04;	/* must be 0 */
+#endif
+	__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 */
+#ifdef __KERNEL__
+	__u8 signature[];
+#endif
+};
+
+/*
+ * Format in which fs-verity file digests are signed in built-in signatures.
+ * 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.
+ *
+ * This struct is specific to the built-in signature verification support, which
+ * is optional.  fs-verity users may also verify signatures in userspace, in
+ * which case userspace is responsible for deciding on what bytes are signed.
+ * This struct may still be used, but it doesn't have to be.  For example,
+ * userspace could instead use a string like "sha256:$digest_as_hex_string".
+ */
+struct fsverity_formatted_digest {
+	char magic[8];			/* must be "FSVerity" */
+	__le16 digest_algorithm;
+	__le16 digest_size;
+	__u8 digest[];
+};
+
 #define FS_IOC_ENABLE_VERITY	_IOW('f', 133, struct fsverity_enable_arg)
 #define FS_IOC_MEASURE_VERITY	_IOWR('f', 134, struct fsverity_digest)
 

lib/compute_digest.c

@@ -17,23 +17,6 @@
 
 #define FS_VERITY_MAX_LEVELS	64
 
-/*
- * 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 */
-};
-
 struct block_buffer {
 	u32 filled;
 	u8 *data;

lib/sign_digest.c

@@ -19,19 +19,6 @@
 #include <openssl/pkcs7.h>
 #include <string.h>
 
-/*
- * 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[];
-};
-
 static int print_openssl_err_cb(const char *str,
 				size_t len __attribute__((unused)),
 				void *u __attribute__((unused)))
@@ -339,7 +326,7 @@ libfsverity_sign_digest(const struct libfsverity_digest *digest,
 	EVP_PKEY *pkey = NULL;
 	X509 *cert = NULL;
 	const EVP_MD *md;
-	struct fsverity_signed_digest *d = NULL;
+	struct fsverity_formatted_digest *d = NULL;
 	int err;
 
 	if (!digest || !sig_params || !sig_ret || !sig_size_ret)  {

programs/cmd_digest.c

@@ -23,13 +23,6 @@ static const struct option longopts[] = {
 	{NULL, 0, NULL, 0}
 };
 
-struct fsverity_signed_digest {
-	char magic[8];			/* must be "FSVerity" */
-	__le16 digest_algorithm;
-	__le16 digest_size;
-	__u8 digest[];
-};
-
 /*
  * Compute the fs-verity measurement of the given file(s), for offline signing.
  */
@@ -68,10 +61,10 @@ int fsverity_cmd_digest(const struct fsverity_command *cmd,
 		goto out_usage;
 
 	for (int i = 0; i < argc; i++) {
-		struct fsverity_signed_digest *d = NULL;
+		struct fsverity_formatted_digest *d = NULL;
 		struct libfsverity_digest *digest = NULL;
 		char digest_hex[FS_VERITY_MAX_DIGEST_SIZE * 2 +
-				sizeof(struct fsverity_signed_digest) * 2 + 1];
+				sizeof(*d) * 2 + 1];
 
 		if (!open_file(&file, argv[i], O_RDONLY, 0))
 			goto out_err;