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Prevent OS certificate store fallback when CA pinning is enabled #54

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Merged
jeffreyparker merged 3 commits into from
Jul 21, 2026
Merged

Prevent OS certificate store fallback when CA pinning is enabled #54

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40fa39d
Prevent OS certificate store fallback when CA pinning is enabled
jeffreyparker Jul 16, 2026
cbd1d76
Remove FileRequester
jeffreyparker Jul 16, 2026
67db1a3
Normalize ca=IGNORE to disable_ca_pinning at the Client layer
jeffreyparker Jul 16, 2026
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10 changes: 7 additions & 3 deletions src/Client.php
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Original file line number Diff line number Diff line change
Expand Up @@ -42,10 +42,8 @@ public function __construct(

if ($requester !== null) {
$this->requester = $requester;
} elseif (in_array("curl", get_loaded_extensions(), true)) {
$this->requester = new CurlRequester();
} else {
$this->requester = new FileRequester();
$this->requester = new CurlRequester();
}

$this->paging = $paging;
Expand All @@ -69,6 +67,12 @@ public function __construct(
*/
public function setRequesterOption($option, $value)
{
// Normalize the legacy ca=IGNORE flag to disable_ca_pinning
if ($option === "ca" && $value === "IGNORE") {
$this->options["disable_ca_pinning"] = true;
unset($this->options["ca"]);
return $this;
}
if ($option === "ca" && isset($this->options["disable_ca_pinning"]) && $this->options["disable_ca_pinning"]) {
throw new \InvalidArgumentException(
"Cannot use custom CA certificates when CA pinning is disabled"
Expand Down
12 changes: 10 additions & 2 deletions src/CurlRequester.php
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,16 @@ public function options($options)
unset($curl_options[CURLOPT_CAINFO]);
} elseif (!isset($curl_options[CURLOPT_CAINFO])) {
$curl_options[CURLOPT_CAINFO] = DEFAULT_CA_CERTS;
} elseif ($curl_options[CURLOPT_CAINFO] == "IGNORE") {
unset($curl_options[CURLOPT_CAINFO]);
}

if (isset($curl_options[CURLOPT_CAINFO])) {
$capath = "/dev/null/" . \bin2hex(\random_bytes(16));
if (!curl_setopt($this->ch, CURLOPT_CAPATH, $capath)) {
throw new \RuntimeException(
"Failed to set CURLOPT_CAPATH; CA pinning cannot be enforced on this cURL/TLS backend"
);
}
$curl_options[CURLOPT_CAPATH] = $capath;
}

// Mandatory configuration options
Expand Down
150 changes: 0 additions & 150 deletions src/FileRequester.php
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This file was deleted.

67 changes: 0 additions & 67 deletions tests/SSL/SSLTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -108,23 +108,6 @@ public function testCorrectlySignedCertificateCurl()
$this->assertTrue($result["success"]);
}

public function testCorrectlySignedCertificateFile()
{
$requester = new \DuoAPI\FileRequester();
$result = $this->pingSSLServer(
$requester,
GOOD_STUNNEL_SERVER,
$this->good_chain
);

/*
* A '404' here is fine. We're simply trying to test if a good
* SSL *connection* is made, there's not a fully implemented API
* waiting for us on the other side of the connection.
*/
$this->assertEquals(404, $result["http_status_code"]);
}

/*
* Test our custom certificate that was signed by our custom CA against
* a third-party certificate chain.
Expand Down Expand Up @@ -153,23 +136,6 @@ public function testMismatchedCertificateCurl()
);
}

public function testMismatchedCertificateFile()
{
$requester = new \DuoAPI\FileRequester();
$result = $this->pingSSLServer(
$requester,
GOOD_STUNNEL_SERVER,
$this->bad_chain
);

$this->assertFalse($result["success"]);
$this->assertEquals($result["response"]["stat"], "FAIL");
$this->assertStringContainsStringIgnoringCase(
"failed to open stream: operation failed",
$result["response"]["message"]
);
}

/*
* Test an unsigned certificate against our custom certificate chain.
*
Expand All @@ -195,23 +161,6 @@ public function testSelfSignedCertificateCurl()
);
}

public function testSelfSignedCertificateFile()
{
$requester = new \DuoAPI\FileRequester();
$result = $this->pingSSLServer(
$requester,
SELF_SIGNED_STUNNEL_SERVER,
$this->good_chain
);

$this->assertFalse($result["success"]);
$this->assertEquals($result["response"]["stat"], "FAIL");
$this->assertStringContainsStringIgnoringCase(
"failed to open stream: operation failed",
$result["response"]["message"]
);
}

/*
* Test a custom certificate with an incorrect hostname that was signed
* by our custom CA against the certificate chain created by our custom CA.
Expand All @@ -238,20 +187,4 @@ public function testCertificateBadHostnameCurl()
);
}

public function testCertificateBadHostnameFile()
{
$requester = new \DuoAPI\FileRequester();
$result = $this->pingSSLServer(
$requester,
BAD_HOSTNAME_STUNNEL_SERVER,
$this->good_chain
);

$this->assertFalse($result["success"]);
$this->assertEquals($result["response"]["stat"], "FAIL");
$this->assertStringContainsStringIgnoringCase(
"failed to open stream: operation failed",
$result["response"]["message"]
);
}
}
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