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[stable17] expose Argon2 options (as we did for bcrypt) #19095

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Merged
rullzer merged 4 commits into from
Mar 5, 2020
Merged

[stable17] expose Argon2 options (as we did for bcrypt) #19095

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d973bc7
expose Argon2 options (as we did for bcrypt)
blizzz Jan 20, 2020
7d1d76b
use getSystemValueInt
blizzz Jan 21, 2020
fb7c218
ignore values that undershoot the minimum, go with default
blizzz Jan 21, 2020
518789a
extended documentation
blizzz Jan 22, 2020
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32 changes: 32 additions & 0 deletions config/config.sample.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1421,6 +1421,38 @@
*/
'tempdirectory' => '/tmp/nextcloudtemp',

/**
* Hashing
*
* Nextcloud uses the Argon2 algorithm (available with PHP >= 7.2 if compiled
* with it) to create hashes by its own and exposes its configuration options as
* following. The default depends on the PHP build. More information can be
* found at: https://www.php.net/manual/en/function.password-hash.php
*/

/**
* The allowed maximum memory in KiB to be used by the algorithm for computing a
* hash. The smallest possible value is 8. Values that undershoot the minimum
* will be ignored in favor of the default.
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@rullzer rullzer Feb 4, 2020

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Shall we just add a big note here to only set this if you are on php7.2 or later?

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@blizzz blizzz Feb 4, 2020

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Not necessary – apart of using the constant. Code wouldn't pick Argon2 if it was not available. There are actually PHP 7.2 builds without Argon2, you cannot just rely on the version.

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@rullzer rullzer Feb 5, 2020

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Then reword it differently. But setting those options if you don't have argon2 basically will do 💥 we just need to be sure nobody does that

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@blizzz blizzz Feb 5, 2020

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Then reword it differently.

Will do

ut setting those options if you don't have argon2 basically will do boom we just need to be sure nobody does that

no, nothing will happen when these options are set. Unless you mean the constants specifically. I take them all out.

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@rullzer rullzer Feb 5, 2020

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I meant the constants.
I'm fine with leaving the constants in. Because they might change over time. And if people set them without argon2 support they will know soon enough. But we should just have a clear warning :)

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@blizzz blizzz Feb 5, 2020

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Because they might change over time

They actually did already, afaik. But anyway, setting there the constants does not make sense anyway, as this is implicit. A URL is given to find more info and also that we rely on defaults. Should be sufficient.

*/
'hashingMemoryCost' => 65536,

/**
* The allowed maximum time in seconds that can be used by the algorithm for
* computing a hash. The value must be an integer, and the minimum value is 1.
* Values that undershoot the minimum will be ignored in favor of the default.
*/
'hashingTimeCost' => 4,

/**
* The allowed number of CPU threads that can be used by the algorithm for
* computing a hash. The value must be an integer, and the minimum value is 1.
* Rationally it does not help to provide a number higher than the available
* threads on the machine. Values that undershoot the minimum will be ignored
* in favor of the default.
*/
'hashingThreads' => 1,

/**
* The hashing cost used by hashes generated by Nextcloud
* Using a higher value requires more time and CPU power to calculate the hashes
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14 changes: 14 additions & 0 deletions lib/private/Security/Hasher.php
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Expand Up @@ -61,6 +61,20 @@ class Hasher implements IHasher {
public function __construct(IConfig $config) {
$this->config = $config;

if (\defined('PASSWORD_ARGON2I')) {
// password_hash fails, when the minimum values are undershot.
// In this case, ignore and revert to default
if ($this->config->getSystemValueInt('hashingMemoryCost', PASSWORD_ARGON2_DEFAULT_MEMORY_COST) >= 8) {
$this->options['memory_cost'] = $this->config->getSystemValueInt('hashingMemoryCost', PASSWORD_ARGON2_DEFAULT_MEMORY_COST);
}
if ($this->config->getSystemValueInt('hashingTimeCost', PASSWORD_ARGON2_DEFAULT_MEMORY_COST) >= 1) {
$this->options['time_cost'] = $this->config->getSystemValueInt('hashingTimeCost', PASSWORD_ARGON2_DEFAULT_TIME_COST);
}
if ($this->config->getSystemValueInt('hashingThreads', PASSWORD_ARGON2_DEFAULT_MEMORY_COST) >= 1) {
$this->options['threads'] = $this->config->getSystemValueInt('hashingThreads', PASSWORD_ARGON2_DEFAULT_THREADS);
}
}

$hashingCost = $this->config->getSystemValue('hashingCost', null);
if(!\is_null($hashingCost)) {
$this->options['cost'] = $hashingCost;
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