MDEV-11782 preparation: Add separate code for validating the 10.1 redo log.

log_crypt_101_read_checkpoint(): Read the encryption information
from a MariaDB 10.1 checkpoint page.

log_crypt_101_read_block(): Attempt to decrypt a MariaDB 10.1
redo log page.

recv_log_format_0_recover(): Only attempt decryption on checksum
mismatch. NOTE: With the MariaDB 10.1 innodb_encrypt_log format,
we can actually determine from the cleartext portion of the redo log
whether the redo log is empty. We do not really have to decrypt the
redo log here, if we did not want to determine if the checksum is valid.

storage/innobase/include/log0crypt.h

 /*****************************************************************************
 
 Copyright (C) 2013, 2015, Google Inc. All Rights Reserved.
-Copyright (C) 2014, 2016, MariaDB Corporation. All Rights Reserved.
+Copyright (C) 2014, 2017, MariaDB Corporation. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -54,6 +54,19 @@ log_crypt_write_checkpoint_buf(
 /*===========================*/
 	byte*	buf);			/*!< in/out: checkpoint buffer */
 
+/** Read the MariaDB 10.1 checkpoint crypto (version, msg and iv) info.
+@param[in]	buf	checkpoint buffer
+@return	whether the operation was successful */
+UNIV_INTERN
+bool
+log_crypt_101_read_checkpoint(const byte* buf);
+
+/** Decrypt a MariaDB 10.1 redo log block.
+@param[in,out]	buf	log block
+@return	whether the decryption was successful */
+bool
+log_crypt_101_read_block(byte* buf);
+
 /*********************************************************************//**
 Read the crypto (version, msg and iv) info, which has been used for
 log blocks with lsn <= this checkpoint's lsn, from a log header's

storage/innobase/log/log0crypt.cc

 /*****************************************************************************
 
 Copyright (C) 2013, 2015, Google Inc. All Rights Reserved.
-Copyright (C) 2014, 2016, MariaDB Corporation. All Rights Reserved.
+Copyright (C) 2014, 2017, MariaDB Corporation. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -455,6 +455,86 @@ log_decrypt_after_read(
 	}
 }
 
+/** Read the MariaDB 10.1 checkpoint crypto (version, msg and iv) info.
+@param[in]	buf	checkpoint buffer
+@return	whether the operation was successful */
+UNIV_INTERN
+bool
+log_crypt_101_read_checkpoint(const byte* buf)
+{
+	buf += 20 + 32 * 9;
+
+	const size_t n = *buf++ == 2 ? std::min(unsigned(*buf++), 5U) : 0;
+
+	for (size_t i = 0; i < n; i++) {
+		struct crypt_info_t info;
+		info.checkpoint_no = mach_read_from_4(buf);
+		info.key_version = mach_read_from_4(buf + 4);
+		memcpy(info.crypt_msg, buf + 8, MY_AES_BLOCK_SIZE);
+		memcpy(info.crypt_nonce, buf + 24, MY_AES_BLOCK_SIZE);
+
+		if (!add_crypt_info(&info, true)) {
+			return false;
+		}
+		buf += 4 + 4 + 2 * MY_AES_BLOCK_SIZE;
+	}
+
+	return true;
+}
+
+/** Decrypt a MariaDB 10.1 redo log block.
+@param[in,out]	buf	log block
+@return	whether the decryption was successful */
+UNIV_INTERN
+bool
+log_crypt_101_read_block(byte* buf)
+{
+	ut_ad(log_block_calc_checksum_format_0(buf)
+	      != log_block_get_checksum(buf));
+	const crypt_info_t* info = get_crypt_info(buf);
+
+	if (!info || info->key_version == 0) {
+		return false;
+	}
+
+	byte dst[OS_FILE_LOG_BLOCK_SIZE];
+	uint dst_len;
+	byte aes_ctr_counter[MY_AES_BLOCK_SIZE];
+
+	const uint src_len = OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_HDR_SIZE;
+
+	ulint log_block_no = log_block_get_hdr_no(buf);
+	lsn_t log_block_start_lsn = log_block_get_start_lsn(
+		srv_start_lsn, log_block_no);
+
+	/* The log block header is not encrypted. */
+	memcpy(dst, buf, LOG_BLOCK_HDR_SIZE);
+
+	memcpy(aes_ctr_counter, info->crypt_nonce, 3);
+	mach_write_to_8(aes_ctr_counter + 3, log_block_start_lsn);
+	mach_write_to_4(aes_ctr_counter + 11, log_block_no);
+	aes_ctr_counter[15] = 0;
+
+	int rc = encryption_crypt(buf + LOG_BLOCK_HDR_SIZE, src_len,
+				  dst + LOG_BLOCK_HDR_SIZE, &dst_len,
+				  const_cast<byte*>(info->crypt_key),
+				  MY_AES_BLOCK_SIZE,
+				  aes_ctr_counter, MY_AES_BLOCK_SIZE,
+				  ENCRYPTION_FLAG_DECRYPT
+				  | ENCRYPTION_FLAG_NOPAD,
+				  LOG_DEFAULT_ENCRYPTION_KEY,
+				  info->key_version);
+
+	if (rc != MY_AES_OK || dst_len != src_len
+	    || log_block_calc_checksum_format_0(dst)
+	    != log_block_get_checksum(dst)) {
+		return false;
+	}
+
+	memcpy(buf, dst, sizeof dst);
+	return true;
+}
+
 /*********************************************************************//**
 Writes the crypto (version, msg and iv) info, which has been used for
 log blocks with lsn <= this checkpoint's lsn, to a log header's

storage/innobase/log/log0recv.cc

@@ -798,7 +798,7 @@ recv_find_max_checkpoint_0(
 		checkpoint_no = mach_read_from_8(
 			buf + LOG_CHECKPOINT_NO);
 
-		if (!log_crypt_read_checkpoint_buf(buf)) {
+		if (!log_crypt_101_read_checkpoint(buf)) {
 			ib::warn() << "Decrypting checkpoint failed";
 			continue;
 		}
@@ -859,10 +859,9 @@ recv_log_format_0_recover(lsn_t lsn)
 			% univ_page_size.physical()),
 		OS_FILE_LOG_BLOCK_SIZE, buf, NULL);
 
-	log_decrypt_after_read(buf, OS_FILE_LOG_BLOCK_SIZE);
-
 	if (log_block_calc_checksum_format_0(buf)
-	    != log_block_get_checksum(buf)) {
+	    != log_block_get_checksum(buf)
+	    && !log_crypt_101_read_block(buf)) {
 		ib::error() << NO_UPGRADE_RECOVERY_MSG
 			<< ", and it appears corrupted"
 			<< NO_UPGRADE_RTFM_MSG;