Bug #52624 [Com]: tempnam() in SAFE Mode
Edit report at http://bugs.php.net/bug.php?id=52624&edit=1
ID: 52624
Comment by: alexis dot olivier at unicaen dot fr
Reported by: hirad dot navid at t-systems dot at
Summary: tempnam() in SAFE Mode
Status: Open
Type: Bug
Package: Unknown/Other Function
Operating System: RHEL 5
PHP Version: 5.2.14
Block user comment: N
Private report: N
New Comment:
Hello everybody,
We got the same case with open_basedir restriction.
The users have no access to /tmp (they have their own tmp dir). When
calling tempnam('/tmp', 'tempname'), The open_basedir restriction takes
effect and creation of the file is forbidden.
But, when calling tempnam('path_that_doesnt_exist', 'tempname'), the
function takes /tmp in fallback and file is created (overriding the
open_basedir restriction). The file can't be written (open_basedir
restriction), but this bug can be used to overflow tmp directory.
I think it lacks a test in the function to protect from writing out of
open_basedir restriction.
Test script:
------------
With open_basedir not including /tmp :
<?php
// This gives a warning
echo tempnam("/tmp", "prefix_");
// This creates a file in /tmp
echo tempnam("directory_that_not_exists", "prefix_");
?>
Previous Comments:
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[2010-08-17 14:39:52] hirad dot navid at t-systems dot at
Description:
------------
Dear php Team,
We are using php 5.2.13 and Safe_mod is ON.
we have a problem using tempnam, at first we had tempnam('',tempfile);
This did not work - error "can not access /tmp
Later I investigated and have written the testscript and have following
behavior. Attention script must be owned by non root user
the script with 7th line $tmp_name = tempnam ( 'tmp', 'tempname' );
works fine also with safe_mode
when i change it to $tmp_name = tempnam ( '/tmp', 'tempname' ); a
safe_mode restriction takes effect (the one with compares UID/GID and
puts out
Warning: tempnam() [function.tempnam]: SAFE MODE Restriction in effect.
The script whose uid/gid is 506/506 is not allowed to access /tmp owned
by uid/gid 0/0 in /home/httpd/html/default/tempfile.php on line 7
but why does it work without the beginning '/'?
Can you clarify this behavior please? and another issuse is that when i
try with $tmp_name = tempnam ( '/tmp', 'tempname' ); it does not make a
diference putting /tmp to openbasedir or safe_mode_includedir it dies
not work.
I have also read the changelog and have found that since PHP 5.2.12 some
issues with tempname and safe_mode have been fixed - there was a bug
that tempnam ignores safe_mode. And this correct because i tested with
php 5.2.11 and it worked with /tmp also. Can you tell me ehat exactly is
changed saince version 5.2.12?
Test script:
---------------
<?PHP
$xx = sys_get_temp_dir();
echo $xx . '<br>';
for ( $x = 0; $x <= 5; $x++ )
{
$tmp_name = tempnam ( 'tmp', 'tempname' );
echo $tmp_name . '<br>';
}
$str = 'standing in a tempfile';
$tmp_file = fopen ( $tmp_name, 'w' );
fputs ( $tmp_file, $str );
fclose ( $tmp_file );
$fp = fopen ( $tmp_name, 'r' );
$str = fgets ( $fp, 50 );
fclose ( $fp );
echo $str;
?>
Expected result:
----------------
script above works fine also in safe mode change 7th line from
$tmp_name = tempnam ( 'tmp', 'tempname' );
to
$tmp_name = tempnam ( '/tmp', 'tempname' ); bringe a safe_mode
restriction which is also ok, but why does it work without / and why
does it not make a diference putting /tmp to openbasedir or
safe_mode_include_dir
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