SQL escape passwords

[grooverdan]

To correctly SQL escape passwords, escaping \ first is
required. Then we need to escape ' in the password to
prevent it being treated as a end of SQL statement quote.

All escaping needs to use , so we cannot be in
NO_BACKSLASH_ESCAPES sql_mode otherwise no escaping will
work.

As an added complication when using the config file within
the entrypoint, for waiting until MariaDB can initialize,
a password mechanism a different escaping applies
(https://mariadb.com/kb/en/configuring-mariadb-with-option-files/).

The printf %q is close, however it provides a much
richer escape of non-printable characters than what can be
read in the configuration file. As such the password
complexity of the root password is limited to escaping
\n, \r, \t, \b, \s, ", ', and \ while for a user
MARIADB_PASSWORD anything, including positively crazy strings
such as \0 will work.

Closes #183

[grooverdan]

todo: look at https://github.com/grooverdan/mariadb/runs/2092312601?check_suite_focus=true fails CI there but not on the PR here.

[tianon]

General idea seems sane (and honestly shouldn't be too surprising to the few users it might break, IMO -- they had to have known they were skating on thin ice by using a password that required escaping 😬).

[tianon]

Does this one also need the NO_BACKSLASH_ESCAPES you added below?

[grooverdan]

its in the same session where rootCreate is used.

[tianon]

Seems like it might be worthwhile to make a new function for this? 😇

[tianon]

Since it's legal to have comments in SQL, do you think it's worth bringing the comment a bit closer to what it's about? ala:

Suggested change

	# we need the SQL_MODE NO_BACKSLASH_ESCAPES mode to be clear for the password to be set.
	# --binary-mode to save us from the semi-mad users who put nulls into passwords
	docker_process_sql --dont-use-mysql-root-password --database=mysql --binary-mode <<-EOSQL
	-- What's done in this file shouldn't be replicated
	-- or products like mysql-fabric won't work
	SET @@SESSION.SQL_LOG_BIN=0;
	SET @@SESSION.SQL_MODE=REPLACE(@@SESSION.SQL_MODE, 'NO_BACKSLASH_ESCAPES', '');
	# --binary-mode to save us from the semi-mad users who put nulls into passwords
	docker_process_sql --dont-use-mysql-root-password --database=mysql --binary-mode <<-EOSQL
	-- What's done in this file shouldn't be replicated
	-- or products like mysql-fabric won't work
	SET @@SESSION.SQL_LOG_BIN=0;
	-- we need the SQL_MODE NO_BACKSLASH_ESCAPES mode to be clear for the password to be set
	SET @@SESSION.SQL_MODE=REPLACE(@@SESSION.SQL_MODE, 'NO_BACKSLASH_ESCAPES', '');

[tianon]

This is probably worth just bringing completely into the printf, ala:

Suggested change

	echo -e "[client]\npassword=$(printf \"%q\" "${MARIADB_ROOT_PASSWORD}")\n"
	printf '[client]\npassword=%q\n' "$MARIADB_ROOT_PASSWORD"

$ printf '[client]\npassword=%q\n' "foo bar baz"
[client]
password=foo\ bar\ baz

[grooverdan]

I'll need to check how MariaDB processes escapes on non-quoted config items.

I would of hoped for a [ -S "${SOCKET}" ] however it seems there's a little too much between listen and the poll/select loop.

[grooverdan]

After far too long looking at this:

• yes, echo -e isn't needed and the printf %q output is the same
• quoting and without quotes, single or double, in .my.cnf has the same effect, except obviously that only the inside the quotes it taken as the string.
• .my.cnf is parsing highly intolerant of \ that printf %q generates.
• printf %q has two output forms - $'......' - remove the $ and it can be passes as a password='......', and "aa\ \"\ a" where \ needs to go to , what other whitespace is quoted this way? ❓ no idea. I think this was my intent with echo -e except it converts too much back, like \r '\n` etc.

The '\x00' character will confuse printf %q, escaping in ESC below will generate some unexpected output, AND any tempt to pass a \x00 containing bash variable to a process will terminate at that character - (strace -fe trace=network -s99 -p $(pidof mysqld) with mysql -u root <<<$'CREATE OR REPLACE USER bob@localhost IDENTIFIED BY \'rr\x00My#1PasswordIsSecure\''. In the entrypoint read -d '' is always \x00 terminated. read -N will stop an '\x00' before EOF (so the bash man pages lies).

So any handling of '\x00' in bash is for the totally mad.

P=$'\'\\aa-\x00-zz"_%'; ESC="${P//\\/\\\\}"; ESC="${ESC//\'/\\\'}"; od -h <<<"$ESC" ; echo LENP=${#P} LENESC=${#ESC}; printf ESC=%q "${ESC}" ; mysql -u root  -p"${MARIADB_ROOT_PASSWORD}" <<<"create or replace user bob@localhost identified by '$ESC';";  mysql -u bob -p"${P}" -e "select 1" ; printf "[client]\npassword=%q\n" "$P" | tee ~/.my.cnf ; mysql -u bob -e 'select 1'; echo "\"$(printf "%q" "$P")\"" 
0000000 275c 5c5c 6161 0a2d
0000010
LENP=5 LENESC=7
ESC=\\\'\\\\aa-+---+
| 1 |
+---+
| 1 |
+---+
[client]
password=\'\\aa-
+---+
| 1 |
+---+
| 1 |
+---+
"\'\\aa-"

ref: ansi string https://wiki.bash-hackers.org/syntax/quoting#ansi_c_like_strings