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feat(lib): Improve remote address handling and overwritecondaddr checks #45651

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feat(lib): Improve remote address handling and overwritecondaddr checks #45651

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68f1100
feat(lib): Improved remote addr parsing to also handle the Forwarded …
aschieweck Jun 3, 2024
0b943ca
feat(lib): also consider trusted proxies when checking overwritecondaddr
aschieweck Jun 3, 2024
143dc84
fix(lib): typos in Request.php
aschieweck Jun 3, 2024
661c541
fix(lib): Request.php now passes the static checks
aschieweck Jun 4, 2024
a00b6f9
refactor(lib): added tests for the new trusted proxy override
aschieweck Jun 9, 2024
2a8c00d
Merge branch 'nextcloud:master' into remote-address-enhancements
aschieweck Jun 18, 2024
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115 changes: 85 additions & 30 deletions lib/private/AppFramework/Http/Request.php
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Original file line number Diff line number Diff line change
Expand Up @@ -555,55 +555,110 @@ protected function isTrustedProxy($trustedProxies, $remoteAddress) {
* @return string IP address
*/
public function getRemoteAddress(): string {
$remoteAddress = isset($this->server['REMOTE_ADDR']) ? $this->server['REMOTE_ADDR'] : '';
$trustedProxies = $this->config->getSystemValue('trusted_proxies', []);
return $this->getRemoteAddressAndProxyChain()['remote_address'];
}

if (\is_array($trustedProxies) && $this->isTrustedProxy($trustedProxies, $remoteAddress)) {
$forwardedForHeaders = $this->config->getSystemValue('forwarded_for_headers', [
'HTTP_X_FORWARDED_FOR'
// only have one default, so we cannot ship an insecure product out of the box
]);

// Read the x-forwarded-for headers and values in reverse order as per
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For#selecting_an_ip_address
foreach (array_reverse($forwardedForHeaders) as $header) {
if (isset($this->server[$header])) {
foreach (array_reverse(explode(',', $this->server[$header])) as $IP) {
$IP = trim($IP);
$colons = substr_count($IP, ':');
if ($colons > 1) {
// Extract IP from string with brackets and optional port
if (preg_match('/^\[(.+?)\](?::\d+)?$/', $IP, $matches) && isset($matches[1])) {
$IP = $matches[1];
/**
* Returns the remote address and the trusted proxy chain from the `forwarded_for_headers`
* @return array{remote_address: string, proxies: list<string>}
*/
public function getRemoteAddressAndProxyChain(): array {
$remoteAddress = $this->server['REMOTE_ADDR'] ?? '';

$trustedProxies = $this->config->getSystemValue('trusted_proxies', []);
if (!is_array($trustedProxies) || count($trustedProxies) == 0 || $this->isTrustedProxy($trustedProxies, $remoteAddress)) {
return ['remote_address' => $remoteAddress, 'proxies' => []];
}

$forwardedForHeaders = $this->config->getSystemValue('forwarded_for_headers', [
'HTTP_X_FORWARDED_FOR', // de-facto standard to keep track of the proxy chain
'HTTP_FORWARDED', // new standard to keep track of the proxy chain
]);
$proxies = [];

foreach ($forwardedForHeaders as $header) {
if (isset($this->server[$header])) {
$proxies = []; // reset for each possible header

$headerContent = $this->server[$header];

$IPs = [];
if (str_contains($headerContent, 'for')) {
// newer HTTP_FORWARDED format
$proxyEntries = explode(',', $headerContent);
foreach ($proxyEntries as $proxy) {
$parts = explode(';', $proxy);
foreach ($parts as $part) {
if (str_starts_with(strtolower(ltrim($part)), 'for') && str_contains($part, '=')) {
$part = substr($part, strpos($part, '=') + 1, strlen($part));
$IPs = array_merge($IPs, explode(',', $part));
}
} elseif ($colons === 1) {
// IPv4 with port
$IP = substr($IP, 0, strpos($IP, ':'));
}
}
} else {
// old school HTTP_X_FORWARDED_FOR format
$IPs = explode(',', $headerContent);
}

if ($this->isTrustedProxy($trustedProxies, $IP)) {
continue;
// Read the x-forwarded-for headers and values in reverse order as per
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For#selecting_an_ip_address
foreach (array_reverse($IPs) as $IP) {
$IP = trim($IP);
$colons = substr_count($IP, ':');
// $colons == 0 -> IPv4 without port, nothing to do
if ($colons === 1) {
// IPv4 with port
$IP = substr($IP, 0, strpos($IP, ':'));
} elseif ($colons > 1) {
// Extract IPv6 from string with brackets and optional port
if (preg_match('/^\[(.+?)\](?::\d+)?$/', $IP, $matches) && isset($matches[1])) {
$IP = $matches[1];
}
}

if (filter_var($IP, FILTER_VALIDATE_IP) !== false) {
return $IP;
}
if (filter_var($IP, FILTER_VALIDATE_IP) === false) {
break;
}

if (!$this->isTrustedProxy($trustedProxies, $IP)) {
$remoteAddress = $IP;
break;
}

$proxies[] = $IP;
}
}
}

return $remoteAddress;
return ['remote_address' => $remoteAddress, 'proxies' => $proxies];
}


/**
* Check overwrite condition
* @return bool
*/
private function isOverwriteCondition(): bool {
$regex = '/' . $this->config->getSystemValueString('overwritecondaddr', '') . '/';
$remoteAddr = isset($this->server['REMOTE_ADDR']) ? $this->server['REMOTE_ADDR'] : '';
return $regex === '//' || preg_match($regex, $remoteAddr) === 1;
if ($regex === '//') {
return true;
}

$remoteAddressAndProxyChain = $this->getRemoteAddressAndProxyChain();
$remoteAddress = $remoteAddressAndProxyChain['remote_address'];
$proxies = $remoteAddressAndProxyChain['proxies'];

if(preg_match($regex, $remoteAddress) === 1) {
return true;
}

foreach ($proxies as $proxy) {
if(preg_match($regex, $proxy) === 1) {
return true;
}
}

return false;
}

/**
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