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Apr 19, 2024
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1 change: 1 addition & 0 deletions .env.example.complete
Original file line number Diff line number Diff line change
Expand Up @@ -267,6 +267,7 @@ OIDC_ISSUER_DISCOVER=false
OIDC_PUBLIC_KEY=null
OIDC_AUTH_ENDPOINT=null
OIDC_TOKEN_ENDPOINT=null
OIDC_USERINFO_ENDPOINT=null
OIDC_ADDITIONAL_SCOPES=null
OIDC_DUMP_USER_DETAILS=false
OIDC_USER_TO_GROUPS=false
Expand Down
146 changes: 4 additions & 142 deletions app/Access/Oidc/OidcIdToken.php
Original file line number Diff line number Diff line change
Expand Up @@ -2,150 +2,21 @@

namespace BookStack\Access\Oidc;

class OidcIdToken
class OidcIdToken extends OidcJwtWithClaims implements ProvidesClaims
{
protected array $header;
protected array $payload;
protected string $signature;
protected string $issuer;
protected array $tokenParts = [];

/**
* @var array[]|string[]
*/
protected array $keys;

public function __construct(string $token, string $issuer, array $keys)
{
$this->keys = $keys;
$this->issuer = $issuer;
$this->parse($token);
}

/**
* Parse the token content into its components.
*/
protected function parse(string $token): void
{
$this->tokenParts = explode('.', $token);
$this->header = $this->parseEncodedTokenPart($this->tokenParts[0]);
$this->payload = $this->parseEncodedTokenPart($this->tokenParts[1] ?? '');
$this->signature = $this->base64UrlDecode($this->tokenParts[2] ?? '') ?: '';
}

/**
* Parse a Base64-JSON encoded token part.
* Returns the data as a key-value array or empty array upon error.
*/
protected function parseEncodedTokenPart(string $part): array
{
$json = $this->base64UrlDecode($part) ?: '{}';
$decoded = json_decode($json, true);

return is_array($decoded) ? $decoded : [];
}

/**
* Base64URL decode. Needs some character conversions to be compatible
* with PHP's default base64 handling.
*/
protected function base64UrlDecode(string $encoded): string
{
return base64_decode(strtr($encoded, '-_', '+/'));
}

/**
* Validate all possible parts of the id token.
*
* @throws OidcInvalidTokenException
*/
public function validate(string $clientId): bool
{
$this->validateTokenStructure();
$this->validateTokenSignature();
parent::validateCommonTokenDetails($clientId);
$this->validateTokenClaims($clientId);

return true;
}

/**
* Fetch a specific claim from this token.
* Returns null if it is null or does not exist.
*
* @return mixed|null
*/
public function getClaim(string $claim)
{
return $this->payload[$claim] ?? null;
}

/**
* Get all returned claims within the token.
*/
public function getAllClaims(): array
{
return $this->payload;
}

/**
* Replace the existing claim data of this token with that provided.
*/
public function replaceClaims(array $claims): void
{
$this->payload = $claims;
}

/**
* Validate the structure of the given token and ensure we have the required pieces.
* As per https://datatracker.ietf.org/doc/html/rfc7519#section-7.2.
*
* @throws OidcInvalidTokenException
*/
protected function validateTokenStructure(): void
{
foreach (['header', 'payload'] as $prop) {
if (empty($this->$prop) || !is_array($this->$prop)) {
throw new OidcInvalidTokenException("Could not parse out a valid {$prop} within the provided token");
}
}

if (empty($this->signature) || !is_string($this->signature)) {
throw new OidcInvalidTokenException('Could not parse out a valid signature within the provided token');
}
}

/**
* Validate the signature of the given token and ensure it validates against the provided key.
*
* @throws OidcInvalidTokenException
*/
protected function validateTokenSignature(): void
{
if ($this->header['alg'] !== 'RS256') {
throw new OidcInvalidTokenException("Only RS256 signature validation is supported. Token reports using {$this->header['alg']}");
}

$parsedKeys = array_map(function ($key) {
try {
return new OidcJwtSigningKey($key);
} catch (OidcInvalidKeyException $e) {
throw new OidcInvalidTokenException('Failed to read signing key with error: ' . $e->getMessage());
}
}, $this->keys);

$parsedKeys = array_filter($parsedKeys);

$contentToSign = $this->tokenParts[0] . '.' . $this->tokenParts[1];
/** @var OidcJwtSigningKey $parsedKey */
foreach ($parsedKeys as $parsedKey) {
if ($parsedKey->verify($contentToSign, $this->signature)) {
return;
}
}

throw new OidcInvalidTokenException('Token signature could not be validated using the provided keys');
}

/**
* Validate the claims of the token.
* As per https://openid.net/specs/openid-connect-basic-1_0.html#IDTokenValidation.
Expand All @@ -156,27 +27,18 @@ protected function validateTokenClaims(string $clientId): void
{
// 1. The Issuer Identifier for the OpenID Provider (which is typically obtained during Discovery)
// MUST exactly match the value of the iss (issuer) Claim.
if (empty($this->payload['iss']) || $this->issuer !== $this->payload['iss']) {
throw new OidcInvalidTokenException('Missing or non-matching token issuer value');
}
// Already done in parent.

// 2. The Client MUST validate that the aud (audience) Claim contains its client_id value registered
// at the Issuer identified by the iss (issuer) Claim as an audience. The ID Token MUST be rejected
// if the ID Token does not list the Client as a valid audience, or if it contains additional
// audiences not trusted by the Client.
if (empty($this->payload['aud'])) {
throw new OidcInvalidTokenException('Missing token audience value');
}

// Partially done in parent.
$aud = is_string($this->payload['aud']) ? [$this->payload['aud']] : $this->payload['aud'];
if (count($aud) !== 1) {
throw new OidcInvalidTokenException('Token audience value has ' . count($aud) . ' values, Expected 1');
}

if ($aud[0] !== $clientId) {
throw new OidcInvalidTokenException('Token audience value did not match the expected client_id');
}

// 3. If the ID Token contains multiple audiences, the Client SHOULD verify that an azp Claim is present.
// NOTE: Addressed by enforcing a count of 1 above.

Expand Down
174 changes: 174 additions & 0 deletions app/Access/Oidc/OidcJwtWithClaims.php
Original file line number Diff line number Diff line change
@@ -0,0 +1,174 @@
<?php

namespace BookStack\Access\Oidc;

class OidcJwtWithClaims implements ProvidesClaims
{
protected array $header;
protected array $payload;
protected string $signature;
protected string $issuer;
protected array $tokenParts = [];

/**
* @var array[]|string[]
*/
protected array $keys;

public function __construct(string $token, string $issuer, array $keys)
{
$this->keys = $keys;
$this->issuer = $issuer;
$this->parse($token);
}

/**
* Parse the token content into its components.
*/
protected function parse(string $token): void
{
$this->tokenParts = explode('.', $token);
$this->header = $this->parseEncodedTokenPart($this->tokenParts[0]);
$this->payload = $this->parseEncodedTokenPart($this->tokenParts[1] ?? '');
$this->signature = $this->base64UrlDecode($this->tokenParts[2] ?? '') ?: '';
}

/**
* Parse a Base64-JSON encoded token part.
* Returns the data as a key-value array or empty array upon error.
*/
protected function parseEncodedTokenPart(string $part): array
{
$json = $this->base64UrlDecode($part) ?: '{}';
$decoded = json_decode($json, true);

return is_array($decoded) ? $decoded : [];
}

/**
* Base64URL decode. Needs some character conversions to be compatible
* with PHP's default base64 handling.
*/
protected function base64UrlDecode(string $encoded): string
{
return base64_decode(strtr($encoded, '-_', '+/'));
}

/**
* Validate common parts of OIDC JWT tokens.
*
* @throws OidcInvalidTokenException
*/
public function validateCommonTokenDetails(string $clientId): bool
{
$this->validateTokenStructure();
$this->validateTokenSignature();
$this->validateCommonClaims($clientId);

return true;
}

/**
* Fetch a specific claim from this token.
* Returns null if it is null or does not exist.
*/
public function getClaim(string $claim): mixed
{
return $this->payload[$claim] ?? null;
}

/**
* Get all returned claims within the token.
*/
public function getAllClaims(): array
{
return $this->payload;
}

/**
* Replace the existing claim data of this token with that provided.
*/
public function replaceClaims(array $claims): void
{
$this->payload = $claims;
}

/**
* Validate the structure of the given token and ensure we have the required pieces.
* As per https://datatracker.ietf.org/doc/html/rfc7519#section-7.2.
*
* @throws OidcInvalidTokenException
*/
protected function validateTokenStructure(): void
{
foreach (['header', 'payload'] as $prop) {
if (empty($this->$prop) || !is_array($this->$prop)) {
throw new OidcInvalidTokenException("Could not parse out a valid {$prop} within the provided token");
}
}

if (empty($this->signature) || !is_string($this->signature)) {
throw new OidcInvalidTokenException('Could not parse out a valid signature within the provided token');
}
}

/**
* Validate the signature of the given token and ensure it validates against the provided key.
*
* @throws OidcInvalidTokenException
*/
protected function validateTokenSignature(): void
{
if ($this->header['alg'] !== 'RS256') {
throw new OidcInvalidTokenException("Only RS256 signature validation is supported. Token reports using {$this->header['alg']}");
}

$parsedKeys = array_map(function ($key) {
try {
return new OidcJwtSigningKey($key);
} catch (OidcInvalidKeyException $e) {
throw new OidcInvalidTokenException('Failed to read signing key with error: ' . $e->getMessage());
}
}, $this->keys);

$parsedKeys = array_filter($parsedKeys);

$contentToSign = $this->tokenParts[0] . '.' . $this->tokenParts[1];
/** @var OidcJwtSigningKey $parsedKey */
foreach ($parsedKeys as $parsedKey) {
if ($parsedKey->verify($contentToSign, $this->signature)) {
return;
}
}

throw new OidcInvalidTokenException('Token signature could not be validated using the provided keys');
}

/**
* Validate common claims for OIDC JWT tokens.
* As per https://openid.net/specs/openid-connect-basic-1_0.html#IDTokenValidation
* and https://openid.net/specs/openid-connect-core-1_0.html#UserInfoResponse
*
* @throws OidcInvalidTokenException
*/
protected function validateCommonClaims(string $clientId): void
{
// 1. The Issuer Identifier for the OpenID Provider (which is typically obtained during Discovery)
// MUST exactly match the value of the iss (issuer) Claim.
if (empty($this->payload['iss']) || $this->issuer !== $this->payload['iss']) {
throw new OidcInvalidTokenException('Missing or non-matching token issuer value');
}

// 2. The Client MUST validate that the aud (audience) Claim contains its client_id value registered
// at the Issuer identified by the iss (issuer) Claim as an audience. The ID Token MUST be rejected
// if the ID Token does not list the Client as a valid audience.
if (empty($this->payload['aud'])) {
throw new OidcInvalidTokenException('Missing token audience value');
}

$aud = is_string($this->payload['aud']) ? [$this->payload['aud']] : $this->payload['aud'];
if (!in_array($clientId, $aud, true)) {
throw new OidcInvalidTokenException('Token audience value did not match the expected client_id');
}
}
}
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