package Test::Taint;
## no critic (Bangs::ProhibitVagueNames)
## We're dealing with abstract vars like "$var" in this code.
=head1 NAME
Test::Taint - Tools to test taintedness
=head1 VERSION
Version 1.06
=cut
use vars qw( $VERSION );
$VERSION = "1.06";
=head1 SYNOPSIS
taint_checking_ok(); # We have to have taint checking on
my $id = "deadbeef"; # Dummy session ID
taint( $id ); # Simulate it coming in from the web
tainted_ok( $id );
$id = validate_id( $id ); # Your routine to check the $id
untainted_ok( $id ); # Did it come back clean?
ok( defined $id );
=head1 DESCRIPTION
Tainted data is data that comes from an unsafe source, such as the
command line, or, in the case of web apps, any GET or POST transactions.
Read the L<perlsec> man page for details on why tainted data is bad,
and how to untaint the data.
When you're writing unit tests for code that deals with tainted data,
you'll want to have a way to provide tainted data for your routines to
handle, and easy ways to check and report on the taintedness of your data,
in standard L<Test::More> style.
=cut
use strict;
use warnings;
use base 'DynaLoader';
use Test::Builder;
use overload;
use Scalar::Util;
use vars qw( $TAINT );
my $Test = Test::Builder->new;
use vars qw( @EXPORT );
@EXPORT = qw(
taint taint_deeply
tainted tainted_deeply
tainted_ok tainted_ok_deeply
untainted_ok untainted_ok_deeply
taint_checking
taint_checking_ok
);
bootstrap Test::Taint $VERSION;
sub import {
my $self = shift;
my $caller = caller;
no strict 'refs';
for my $sub ( @EXPORT ) {
*{$caller.'::'.$sub} = \&{$sub};
}
$Test->exported_to($caller);
$Test->plan(@_);
} # import
sub _deeply_traverse {
my $callback = shift;
my @stack = \@_;
my %seen;
while(@stack) {
my $node = pop @stack;
# skip the node if its not a reference
next unless defined $node;
my($realpack, $realtype, $id) = overload::StrVal($node) =~ /\A(?:(.+)\=)?(HASH|ARRAY|GLOB|SCALAR|REF)\((0x[[:xdigit:]]+)\)\z/
or next;
# taint the contents of tied objects
if(my $tied = $realtype eq 'HASH' ? tied %{$node} :
$realtype eq 'ARRAY' ? tied @{$node} :
$realtype eq 'SCALAR' ? tied ${$node} :
$realtype eq 'REF' ? tied ${$node} : undef) {
push @stack, $tied;
next;
}
# prevent circular references from being traversed
no warnings 'uninitialized';
next if $seen{$realpack, $realtype, $id}++;
# perform an action on the node, then push them on the stack for traversal
push @stack,
$realtype eq 'HASH' ? $callback->(values %{$node}) :
$realtype eq 'ARRAY' ? $callback->(@{$node}) :
$realtype eq 'SCALAR' ? $callback->(${$node}) :
$realtype eq 'REF' ? $callback->(${$node}) :
map $callback->(*$node{$_}), qw(SCALAR ARRAY HASH); #must be a GLOB
}
return;
} # _deeply_traverse
=head1 C<Test::More>-style Functions
All the C<xxx_ok()> functions work like standard C<Test::More>-style
functions, where the last parm is an optional message, it outputs ok or
not ok, and returns a boolean telling if the test passed.
=head2 taint_checking_ok( [$message] )
L<Test::More>-style test that taint checking is on. This should probably
be the first thing in any F<*.t> file that deals with taintedness.
=cut
sub taint_checking_ok {
my $msg = @_ ? shift : "Taint checking is on";
my $ok = taint_checking();
$Test->ok( $ok, $msg );
return $ok;
} # taint_checking_ok
=head2 tainted_ok( $var [, $message ] )
Checks that I<$var> is tainted.
tainted_ok( $ENV{FOO} );
=cut
sub tainted_ok {
my $var = shift;
my $msg = shift;
my $ok = tainted( $var );
$Test->ok( $ok, $msg );
return $ok;
} # tainted_ok
=head2 untainted_ok( $var [, $message ] )
Checks that I<$var> is not tainted.
my $foo = my_validate( $ENV{FOO} );
untainted_ok( $foo );
=cut
sub untainted_ok {
my $var = shift;
my $msg = shift;
my $ok = !tainted( $var );
$Test->ok( $ok, $msg );
return $ok;
} # untainted_ok
=head2 tainted_ok_deeply( $var [, $message ] )
Checks that I<$var> is tainted. If I<$var>
is a reference, it recursively checks every
variable to make sure they are all tainted.
tainted_ok_deeply( \%ENV );
=cut
sub tainted_ok_deeply {
my $var = shift;
my $msg = shift;
my $ok = tainted_deeply( $var );
$Test->ok( $ok, $msg );
return $ok;
} # tainted_ok_deeply
=head2 untainted_ok_deeply( $var [, $message ] )
Checks that I<$var> is not tainted. If I<$var>
is a reference, it recursively checks every
variable to make sure they are all not tainted.
my %env = my_validate( \%ENV );
untainted_ok_deeply( \%env );
=cut
sub untainted_ok_deeply {
my $var = shift;
my $msg = shift;
my $ok = !tainted_deeply( $var );
$Test->ok( $ok, $msg );
return $ok;
} # untainted_ok_deeply
=head1 Helper Functions
These are all helper functions. Most are wrapped by an C<xxx_ok()>
counterpart, except for C<taint> which actually does something, instead
of just reporting it.
=head2 taint_checking()
Returns true if taint checking is enabled via the -T flag.
=cut
sub taint_checking() {
return tainted( $Test::Taint::TAINT );
} # taint_checking
=head2 tainted( I<$var> )
Returns boolean saying if C<$var> is tainted.
=cut
sub tainted {
no warnings qw(void uninitialized);
return !eval { local $SIG{__DIE__} = 'DEFAULT'; join('', shift), kill 0; 1 };
} # tainted
=head2 tainted_deeply( I<$var> )
Returns boolean saying if C<$var> is tainted. If
C<$var> is a reference it recursively checks every
variable to make sure they are all tainted.
=cut
sub tainted_deeply {
my $is_tainted = 1;
_deeply_traverse(
sub {
foreach (@_) {
next
if not defined
or ref
or Scalar::Util::readonly $_
or tainted $_;
$is_tainted = 0;
last;
}
return @_;
},
shift,
);
return $is_tainted;
} # tainted_deeply
=head2 taint( @list )
Marks each (apparently) taintable argument in I<@list> as being tainted.
References can be tainted like any other scalar, but it doesn't make
sense to, so they will B<not> be tainted by this function.
Some C<tie>d and magical variables may fail to be tainted by this routine,
try as it may.)
=cut
sub taint {
local $_;
for ( @_ ) {
_taint($_) unless ref or Scalar::Util::readonly $_;
}
} # taint
# _taint() is an external function in Taint.xs
=head2 taint_deeply( @list )
Similar to C<taint>, except that if any elements in I<@list> are
references, it walks deeply into the data structure and marks each
taintable argument as being tainted.
If any variables are C<tie>d this will taint all the scalars within
the tied object.
=cut
sub taint_deeply {
_deeply_traverse(
sub { taint @_; @_ },
@_,
);
return;
} # taint_deeply
BEGIN {
MAKE_SOME_TAINT: {
# Somehow we need to get some taintedness into $Test::Taint::TAINT
# Let's try the easy way first. Either of these should be
# tainted, unless somebody has untainted them, so this
# will almost always work on the first try.
# (Unless, of course, taint checking has been turned off!)
$TAINT = substr("$0$^X", 0, 0);
last if tainted $TAINT;
# Let's try again. Maybe somebody cleaned those.
$TAINT = substr(join('', @ARGV, %ENV), 0, 0);
last if tainted $TAINT;
# If those don't work, go try to open some file from some unsafe
# source and get data from them. That data is tainted.
# (Yes, even reading from /dev/null works!)
local(*FOO);
for ( qw(/dev/null / . ..), values %INC, $0, $^X ) {
next unless defined $_;
if ( open FOO, $_ ) {
my $potentially_tainted_data;
if ( defined sysread FOO, $potentially_tainted_data, 1 ) {
$TAINT = substr( $potentially_tainted_data, 0, 0 );
last if tainted $TAINT;
}
}
}
close FOO;
}
# Sanity check
die 'Our taintbrush should have zero length!' if length $TAINT;
}
=head1 AUTHOR
Written by Andy Lester, C<< <andy@petdance.com> >>.
=head1 COPYRIGHT
Copyright 2004, Andy Lester, All Rights Reserved.
You may use, modify, and distribute this package under the
same terms as Perl itself.
=cut
1;