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Time attack protection on hmac comparison

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This fixes issue 2.7 of https://defuse.ca/audits/zerobin.htm, and thus
(with commit a24212afda90ca3e4b4ff5ce30d2012709b58a28) also issue 2.8.

(cherry picked from commit 0b4db7ece313dd268e51fc47a0293a649927558a)

Conflicts:
	index.php
This commit is contained in:
Sebastien SAUVAGE 2014-02-06 22:52:17 +01:00 • committed by El RIDO
parent daf5522b1e
commit 43a439e7d0
6 changed files with 135 additions and 58 deletions
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118
lib/zerobin.php
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@ -272,8 +272,8 @@ class zerobin
$pasteid = $_POST['pasteid'];
$parentid = $_POST['parentid'];
if (
!preg_match('#\A[a-f\d]{16}\z#', $pasteid) ||
!preg_match('#\A[a-f\d]{16}\z#', $parentid)
!filter::is_valid_paste_id($pasteid) ||
!filter::is_valid_paste_id($parentid)
) $this->_return_message(1, 'Invalid data.');
// Comments do not expire (it's the paste that expires)
@ -340,18 +340,21 @@ class zerobin
private function _delete($dataid, $deletetoken)
{
// Is this a valid paste identifier?
if (preg_match('#\A[a-f\d]{16}\z#', $dataid))
if (!filter::is_valid_paste_id($dataid))
{
// Check that paste exists.
if (!$this->_model()->exists($dataid))
{
$this->_error = 'Paste does not exist, has expired or has been deleted.';
return;
}
$this->_error = 'Invalid paste ID.';
return;
}
// Check that paste exists.
if (!$this->_model()->exists($dataid))
{
$this->_error = 'Paste does not exist, has expired or has been deleted.';
return;
}
// Make sure token is valid.
if ($deletetoken != hash_hmac('sha1', $dataid , serversalt::get()))
if (filter::slow_equals($deletetoken, hash_hmac('sha1', $dataid , serversalt::get())))
{
$this->_error = 'Wrong deletion token. Paste was not deleted.';
return;
@ -372,63 +375,62 @@ class zerobin
private function _read($dataid)
{
// Is this a valid paste identifier?
if (preg_match('#\A[a-f\d]{16}\z#', $dataid))
if (!filter::is_valid_paste_id($dataid))
{
// Check that paste exists.
if ($this->_model()->exists($dataid))
$this->_error = 'Invalid paste ID.';
return;
}
// Check that paste exists.
if ($this->_model()->exists($dataid))
{
// Get the paste itself.
$paste = $this->_model()->read($dataid);
// See if paste has expired.
if (
isset($paste->meta->expire_date) &&
$paste->meta->expire_date < time()
)
{
// Get the paste itself.
$paste = $this->_model()->read($dataid);
// See if paste has expired.
if (
isset($paste->meta->expire_date) &&
$paste->meta->expire_date < time()
)
{
// Delete the paste
$this->_model()->delete($dataid);
$this->_error = 'Paste does not exist, has expired or has been deleted.';
}
// If no error, return the paste.
else
{
// We kindly provide the remaining time before expiration (in seconds)
if (
property_exists($paste->meta, 'expire_date')
) $paste->meta->remaining_time = $paste->meta->expire_date - time();
// The paste itself is the first in the list of encrypted messages.
$messages = array($paste);
// If it's a discussion, get all comments.
if (
property_exists($paste->meta, 'opendiscussion') &&
$paste->meta->opendiscussion
)
{
$messages = array_merge(
$messages,
$this->_model()->readComments($dataid)
);
}
$this->_data = json_encode($messages);
// If the paste was meant to be read only once, delete it.
if (
property_exists($paste->meta, 'burnafterreading') &&
$paste->meta->burnafterreading
) $this->_model()->delete($dataid);
}
// Delete the paste
$this->_model()->delete($dataid);
$this->_error = 'Paste does not exist, has expired or has been deleted.';
}
// If no error, return the paste.
else
{
$this->_error = 'Paste does not exist or has expired.';
// We kindly provide the remaining time before expiration (in seconds)
if (
property_exists($paste->meta, 'expire_date')
) $paste->meta->remaining_time = $paste->meta->expire_date - time();
// The paste itself is the first in the list of encrypted messages.
$messages = array($paste);
// If it's a discussion, get all comments.
if (
property_exists($paste->meta, 'opendiscussion') &&
$paste->meta->opendiscussion
)
{
$messages = array_merge(
$messages,
$this->_model()->readComments($dataid)
);
}
$this->_data = json_encode($messages);
// If the paste was meant to be read only once, delete it.
if (
property_exists($paste->meta, 'burnafterreading') &&
$paste->meta->burnafterreading
) $this->_model()->delete($dataid);
}
}
else
{
$this->_error = 'Invalid paste ID.';
$this->_error = 'Paste does not exist or has expired.';
}
}