Escape string inside update_pgpass command

[src386]

Pull Request (PR) description

The update_pgpass resource may fail when using strong ${database_password} that contain special characters such as & because the echoed string is not escaped. This Pull request adds double quotes shell_escape() (as suggested by @smortex).

This Pull Request (PR) fixes the following issues

• Fixes Exec[update_pgpass] failed #830

[smortex]

I can be even more creative 😈 :

romain@desktop-fln40kq ~ % sudo -u postgres createdb 'foo bar'
romain@desktop-fln40kq ~ % sudo -u postgres createdb 'foo:bar'
romain@desktop-fln40kq ~ % sudo -u postgres createuser 'foo bar baz'
romain@desktop-fln40kq ~ % sudo -u postgres createuser 'foo:bar:baz'

The spaces will break the command, and according to https://www.postgresql.org/docs/current/libpq-pgpass.html:

If an entry needs to contain : or \, escape this character with \.

So I think we should also escape the database_name, database_user and database_password accordingly (I do not think these chars are valid for a hostname), and then shell-escape the whole pattern:

$escaped_database_name     = $database_name.regsubst('[\\\\:]', '\\\\\\0', 'G')
$escaped_database_user     = $database_user.regsubst('[\\\\:]', '\\\\\\0', 'G')
$escaped_database_password = $database_password.regsubst('[\\\\:]', '\\\\\\0', 'G')

Suggested change

	unless => "grep ${database_host}:5432:${database_name}:${database_user}:${shell_escape($database_password)} /root/.pgpass",
	unless => "grep ${"${database_host}:5432:${escaped_database_name}:${escaped_database_user}:${escaped_database_password}".shell_escape} /root/.pgpass",

I only tested the pattern substitution (which required much escaping than i though), so we probably need to test this for real with users with annoying chars in their name to be sure it is fine.

But all this is probably overkill, maybe we can just detect "forbidden" chars and raise an error because nobody wants to do this kind of things?

[xchotard-talentsoft]

In my opinion postgresql admins should know that they must avoid special characters in databases names and usernames. This is a bit different for passwords than can be sometimes randomly generated or have strong complexity requirements. In my case I used pwgen to get a strong password.

They should also know that escape characters in passwords will break everything and must be avoided. So I think this is reasonable to keep the fix as simple as possible.

[ekohl]

In #904 I've taken another approach where I provide all the data via env vars, removing the need for the pgpass file altogether.