1Safe(3) User Contributed Perl Documentation Safe(3)
2
6 DBIx::Safe - Safer access to your database through a DBI database
7 handle
8
10 This documents version 1.2.5 of the DBIx::Safe module
11
13 use DBIx::Safe;
14 $dbh = DBI->connect($dbn, $user, $pass, {AutoCommit => 0});
16 my $safedbh = DBIx::Safe->new({ dbh => $dbh });
18 $safedbh->allow_command('SELECT INSERT UPDATE');
20 $safedbh->allow_regex(qr{LOCK TABLE \w+ IN EXCLUSIVE MODE});
22 $safedbh->deny_regex(qr{LOCK TABLE pg_});
24 $safedbh->allow_attribute('PrintError RaiseError');
26
28 The purpose of this module is to give controlled, limited access to an
29 application, rather than simply passing it a raw database handle
30 through DBI. DBIx::Safe acts as a wrapper to the database, by only
31 allowing through the commands you tell it to. It filters all things
32 related to the database handle - methods and attributes.
33 The typical usage is for your application to create a database handle
35 via a normal DBI call to new(), then pass that to DBIx::Safe->new(),
36 which will return you a DBIx::Safe object. After specifying exactly
37 what is and what is not allowed, you can pass the object to the
38 untrusted application. The object will act very similar to a DBI
39 database handle, and in most cases can be used interchangeably.
40 By default, nothing is allowed to run at all. There are many things you
42 can control. You can specify which SQL commands are allowed, by
43 indicating the first word in the SQL statement (e.g. 'SELECT'). You can
44 specify which database methods are allowed to run (e.g. 'ping'). You
45 can specify a regular expression that allows matching SQL statements to
46 run (e.g. 'qr{SET TIMEZONE}'). You can specify a regular expression
47 that is NOT allowed to run (e.g. qr(UPDATE xxx}). Finally, you can
48 indicate which database attributes are allowed to be read and changed
49 (e.g. 'PrintError'). For all of the above, there are matching methods
50 to remove them as well.
51 Deciding what statements to allow
53 Anytime a statement is sent to the server via the DBIx::Safe database
54 handle, it is first examined to see if it is allowed to run or not.
55 There are three major checks that occur when a statement is sent.
56 First, the initial word of the statement, known as the command, is
57 extracted. Next, the entire statement is checked against the list of
58 denied regular expressions. Next, the command is checked against the
59 list of allowed commands. If there is no match, the statement is
60 checked against the list of allowed regular expressions.
61 Each DBD may implement additional or slightly different checks. For
63 example, if using Postgres, no semi-colons are allowed unless the
64 command is one of SELECT, INSERT, UPDATE, or DELETE, to prevent
65 multiple commands from running. (The four listed commands can be
66 checked in another way for multiple commands, so they are allowed to
67 have semicolons).
68 Deciding what attributes to allow
70 Database handle attributes are controlled by a single list of allowed
71 keys. If the key is allowed, the underlying database handle value is
72 returned or changed (or both). Note that the attribute "AutoCommit" is
73 never allowed to be changed.
74 Methods
76 new()
77 Creates a new DBIx::Safe object. Requires a mandatory "dbh" argument
79 containing an active database handle. Optional arguments are
80 "allow_command", "allow_regex", "deny_regex", and "allow_attribute".
81 allow_command()
83 Specifies which commands are allowed to be used. Can be a whitespace-
85 separated list of words in a string, or an arrayref of such strings.
86 Returns the current list of allowed commands. Duplicate commands will
87 throw an error.
88 unallow_command()
90 Same as allow_command, but will remove words from the list.
92 allow_regex()
94 Specifies regular expressions which are allowed to run. Argument must
96 be a regular expression, or an arrayref of regular expressions. Returns
97 the current list.
98 unallow_regex()
100 Same as allow_regex, but will remove regexes from the list.
102 deny_regex()
104 Specifies regular expressions which are NOT allowed to run. Arguments
106 and return the same as allow_regex().
107 undeny regex()
109 Same as deny_regex, but will remove regexes from the list.
111 allow_attribute()
113 Specifies database handle attributes that are allowed to be changed. By
115 default, nothing can be read. Argument is a whitespace-separated list
116 of words in a string, or an arrayref of such strings. Returns the
117 current list.
118 unallow_attribute()
120 Same as allow_attributes, but removes attributes from the list.
122 Testing
124 DBIx::Safe has a very comprehensive test suite, so please use it! The
125 only thing you should need is a database connection, by setting the
126 environment variables DBI_DSN and DBI_USER (and DBI_PASS if needed).
127 You can optionally run the module through Perl::Critic by setting the
129 TEST_AUTHOR environment variable. You will need to have the modules
130 Perl::Critic and Test::Perl::Critic installed.
131 Please report any test failures to the author or
133 bucardo-general@bucardo.org.
134 Supported Databases
136 Due to the difficulty of ensuring safe access to the database, each
137 type of database must be specifically written into DBIx::Safe. Current
138 databases supported are: Postgres (DBD::Pg).
139
141 The latest version and other information about DBIx::Safe can be found
142 at: http://bucardo.org/dbix_safe/
143
145 The latest development version can be checked out by using git:
146 git clone http://bucardo.org/dbixsafe.git/
148
150 Bugs should be reported to the author or bucardo-general@bucardo.org.
151
153 Greg Sabino Mullane <greg@endpoint.com>
154
156 Copyright 2006-2007 Greg Sabino Mullane <greg@endpoint.com>.
157 This software is free to use: see the LICENSE file for details.
159perl v5.32.0 2020-07-28 Safe(3)