MDEV-28798: Previously Binlog Encrypted Master Segfaults on Binlog Dump with Using_Gtid=Slave_Pos

Problem:
========
A master can segfault if it can't set up decryption for its binary
log during a binlog dump with Using_Gtid=Slave_Pos. If slave
connects using GTID mode, the master will call into
log.cc::get_gtid_list_event(), which iterate through binlog events
looking for a Gtid_list_log_event. On an encrypted binlog that the
master cannot decrypt, the first event will be a
START_ENCRYPTION_EVENT which will call into the following decryption branch

if (fdle->start_decryption((Start_encryption_log_event*) ev))
  errormsg= ‘Could not set up decryption for binlog.’;

The event iteration however, does not stop in spite of this error.
The master will try to read the next event, but segfault while
trying to decrypt it because decryption failed to initialize.

Solution:
========
Break the event iteration if decryption cannot be set up.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted.result → mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted_coords.result

@@ -4,6 +4,7 @@
 include/rpl_init.inc [topology=1->2]
 connection server_2;
 include/stop_slave.inc
+CHANGE MASTER TO MASTER_USE_GTID=NO;
 #####################################################
 # Part 1: unencrypted master
 #####################################################

mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted.test → mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted_coords.test

 #
-# TODO: write here what the test checks after MDEV-11288 is fixed
-#
 # The test starts with unencrypted master. 
 # It stops replication, generates a few statement and row events
 # on the master, then restarts the server with encrypted binlog, 
 # generates some more events and restarts it back without encryption 
 # (no encryption plugin).
-# Then it resumes replication and checks what happens when the server
-# tries to feed the binary logs (included the encrypted ones) 
-# to the slave.
+# Then it resumes replication and should error with
+# ER_MASTER_FATAL_ERROR_READING_BINLOG because the encrypted binlog is
+# sent and unable to be decrypted.
+#
+# Note this variation of encrypted_master_switch_to_unencrypted tests
+# using MASTER_USE_GTID=NO. In contrast to the GTID variant of this
+# test, at part 3 (the error case), the master will scan binlogs
+# starting from the first one (which is unencrypted initially, so
+# replication is okay) and continue until the slave encounters the
+# first encrypted event, which causes the slave to error.
 #
 
 --source include/have_binlog_format_mixed.inc
@@ -27,6 +32,7 @@
 --connection server_2
 --disable_connect_log
 --source include/stop_slave.inc
+CHANGE MASTER TO MASTER_USE_GTID=NO;
 --enable_connect_log
 
 --echo #####################################################

mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted_gtid.cnf

+!include my.cnf
+
+[mysqld.1]
+encrypt-binlog=0
+skip-file-key-management
+
+[mysqld.2]
+gtid-domain-id=1

mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted_gtid.result

+#################
+# Initialization
+#################
+include/rpl_init.inc [topology=1->2]
+connection server_2;
+include/stop_slave.inc
+CHANGE MASTER TO MASTER_USE_GTID=SLAVE_POS;
+call mtr.add_suppression(" Got fatal error 1236 from master when reading data from binary log: 'Could not set up decryption for binlog.'");
+#####################################################
+# Part 1: unencrypted master
+#####################################################
+connection server_1;
+CREATE TABLE table1_no_encryption (
+pk INT AUTO_INCREMENT PRIMARY KEY,
+ts TIMESTAMP NULL,
+b BLOB
+) ENGINE=MyISAM;
+INSERT INTO table1_no_encryption VALUES (NULL,NOW(),'data_no_encryption');
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+FLUSH BINARY LOGS;
+SET binlog_format=ROW;
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+NOT FOUND /table1_no_encryption/ in master-bin.0*
+#####################################################
+# Part 2: restart master, now with binlog encryption
+#####################################################
+connection default;
+connection server_1;
+CREATE TABLE table2_to_encrypt (
+pk INT AUTO_INCREMENT PRIMARY KEY,
+ts TIMESTAMP NULL,
+b BLOB
+) ENGINE=MyISAM;
+INSERT INTO table2_to_encrypt VALUES (NULL,NOW(),'data_to_encrypt');
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+FLUSH BINARY LOGS;
+SET binlog_format=ROW;
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+NOT FOUND /table2_to_encrypt/ in master-bin.0*
+#####################################################
+# Part 3: restart master again without encryption
+#####################################################
+connection default;
+connection server_1;
+CREATE TABLE table3_no_encryption (
+pk INT AUTO_INCREMENT PRIMARY KEY,
+ts TIMESTAMP NULL,
+b BLOB
+) ENGINE=MyISAM;
+INSERT INTO table3_no_encryption VALUES (NULL,NOW(),'data_no_encryption');
+INSERT INTO table3_no_encryption SELECT NULL,NOW(),b FROM table3_no_encryption;
+INSERT INTO table3_no_encryption SELECT NULL,NOW(),b FROM table3_no_encryption;
+#####################################################
+# Check: resume replication and check how it goes
+#####################################################
+connection server_2;
+start slave;
+include/wait_for_slave_io_error.inc [errno=1236]
+# Ensuring slave was unable to replicate any transactions..
+# ..success
+SHOW TABLES;
+Tables_in_test
+include/stop_slave.inc
+reset slave;
+##########
+# Cleanup
+##########
+connection server_1;
+reset master;
+SELECT COUNT(*) FROM table1_no_encryption;
+COUNT(*)
+8
+SELECT COUNT(*) FROM table2_to_encrypt;
+COUNT(*)
+8
+SELECT COUNT(*) FROM table3_no_encryption;
+COUNT(*)
+4
+DROP TABLE table1_no_encryption, table2_to_encrypt, table3_no_encryption;
+connection server_2;
+include/start_slave.inc
+include/rpl_end.inc

mysql-test/suite/binlog_encryption/encrypted_master_switch_to_unencrypted_gtid.test

+#
+# The test starts with unencrypted master.
+# It stops replication, generates a few statement and row events
+# on the master, then restarts the server with encrypted binlog,
+# generates some more events and restarts it back without encryption
+# (no encryption plugin).
+# Then it resumes replication and should error with
+# ER_MASTER_FATAL_ERROR_READING_BINLOG because the encrypted binlog is
+# sent and unable to be decrypted.
+#
+# Note this variation of encrypted_master_switch_to_unencrypted tests
+# using MASTER_USE_GTID=SLAVE_POS. encrypted_master_switch_to_unencrypted
+# was the original test which only used binlog coordinates. When tested
+# using MASTER_USE_GTID=Slave_Pos, the master optimizes the detection of
+# an undecryptable binlog. I.e, the master will initially look for a
+# Gtid_list_log_event, but fail to decrypt it and fail immediately in
+# part 3.
+#
+
+--source include/have_binlog_format_mixed.inc
+
+--echo #################
+--echo # Initialization
+--echo #################
+
+--let $rpl_topology= 1->2
+--source include/rpl_init.inc
+
+--enable_connect_log
+
+# We stop replication because we want it to happen after the switch
+
+--connection server_2
+--disable_connect_log
+--source include/stop_slave.inc
+CHANGE MASTER TO MASTER_USE_GTID=SLAVE_POS;
+--enable_connect_log
+call mtr.add_suppression(" Got fatal error 1236 from master when reading data from binary log: 'Could not set up decryption for binlog.'");
+
+--echo #####################################################
+--echo # Part 1: unencrypted master
+--echo #####################################################
+
+--connection server_1
+
+CREATE TABLE table1_no_encryption (
+  pk INT AUTO_INCREMENT PRIMARY KEY,
+  ts TIMESTAMP NULL,
+  b BLOB
+) ENGINE=MyISAM;
+
+INSERT INTO table1_no_encryption VALUES (NULL,NOW(),'data_no_encryption');
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+FLUSH BINARY LOGS;
+SET binlog_format=ROW;
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+INSERT INTO table1_no_encryption SELECT NULL,NOW(),b FROM table1_no_encryption;
+
+# Make sure that binary logs are not encrypted
+
+--let SEARCH_RANGE = 500000
+--let SEARCH_FILE= master-bin.0*
+--let SEARCH_PATTERN= table1_no_encryption
+--source include/search_pattern_in_file.inc
+
+--echo #####################################################
+--echo # Part 2: restart master, now with binlog encryption
+--echo #####################################################
+
+--let $rpl_server_parameters= --encrypt-binlog=1 --plugin-load-add=$FILE_KEY_MANAGEMENT_SO --file-key-management --loose-file-key-management-filename=$MYSQL_TEST_DIR/std_data/keys.txt
+
+--let $rpl_server_number= 1
+--source restart_server.inc
+
+CREATE TABLE table2_to_encrypt (
+  pk INT AUTO_INCREMENT PRIMARY KEY,
+  ts TIMESTAMP NULL,
+  b BLOB
+) ENGINE=MyISAM;
+
+INSERT INTO table2_to_encrypt VALUES (NULL,NOW(),'data_to_encrypt');
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+FLUSH BINARY LOGS;
+SET binlog_format=ROW;
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+INSERT INTO table2_to_encrypt SELECT NULL,NOW(),b FROM table2_to_encrypt;
+
+# Make sure that binary logs are encrypted
+
+--let SEARCH_FILE= master-bin.0*
+--let SEARCH_PATTERN= table2_to_encrypt
+--source include/search_pattern_in_file.inc
+
+--echo #####################################################
+--echo # Part 3: restart master again without encryption
+--echo #####################################################
+
+--let $rpl_server_parameters= --encrypt-binlog=0
+--let $rpl_server_number= 1
+--source restart_server.inc
+
+CREATE TABLE table3_no_encryption (
+  pk INT AUTO_INCREMENT PRIMARY KEY,
+  ts TIMESTAMP NULL,
+  b BLOB
+) ENGINE=MyISAM;
+
+INSERT INTO table3_no_encryption VALUES (NULL,NOW(),'data_no_encryption');
+INSERT INTO table3_no_encryption SELECT NULL,NOW(),b FROM table3_no_encryption;
+INSERT INTO table3_no_encryption SELECT NULL,NOW(),b FROM table3_no_encryption;
+
+--echo #####################################################
+--echo # Check: resume replication and check how it goes
+--echo #####################################################
+
+--connection server_2
+start slave;
+# Make slave to try to synchronize. It shouldn't work, the slave IO thread is
+# expected to abort with an error
+--let $slave_io_errno= 1236
+--source include/wait_for_slave_io_error.inc
+
+--echo # Ensuring slave was unable to replicate any transactions..
+--let $gsp= `SELECT @@global.gtid_slave_pos`
+if (`SELECT strcmp("$gsp","")`)
+{
+  die Slave without encryption configured should fail to read encrypted binlog;
+}
+--echo # ..success
+
+--sorted_result
+SHOW TABLES;
+
+--disable_connect_log
+--source include/stop_slave.inc
+--enable_connect_log
+reset slave;
+
+--echo ##########
+--echo # Cleanup
+--echo ##########
+
+--connection server_1
+reset master;
+
+SELECT COUNT(*) FROM table1_no_encryption;
+SELECT COUNT(*) FROM table2_to_encrypt;
+SELECT COUNT(*) FROM table3_no_encryption;
+DROP TABLE table1_no_encryption, table2_to_encrypt, table3_no_encryption;
+
+--connection server_2
+--disable_connect_log
+--source include/start_slave.inc
+--source include/rpl_end.inc

sql/log.cc

@@ -10786,7 +10786,10 @@ get_gtid_list_event(IO_CACHE *cache, Gtid_list_log_event **out_gtid_list)
     if (typ == START_ENCRYPTION_EVENT)
     {
       if (fdle->start_decryption((Start_encryption_log_event*) ev))
+      {
         errormsg= "Could not set up decryption for binlog.";
+        break;
+      }
     }
     delete ev;
     if (typ == ROTATE_EVENT || typ == STOP_EVENT ||