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tvdijentvdijen
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Refactor
1 parent 4f66ed1 commit 2c24f2b

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5 files changed

+508
-212
lines changed

5 files changed

+508
-212
lines changed

‎src/Assert/Assert.php‎

Lines changed: 0 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -9,29 +9,23 @@
99
/**
1010
* @package simplesamlphp/xml-common
1111
*
12-
* @method static void validAllowedXPathAxes(mixed $value, array $allowed_axes, string $message = '', string $exception = '')
1312
* @method static void validAllowedXPathFilter(mixed $value, array $allowed_axes, array $allowed_functions, string $message = '', string $exception = '')
14-
* @method static void validAllowedXPathFunctions(mixed $value, array $allowed_functions, string $message = '', string $exception = '')
1513
* @method static void validHexBinary(mixed $value, string $message = '', string $exception = '')
1614
* @method static void validNMToken(mixed $value, string $message = '', string $exception = '')
1715
* @method static void validNMTokens(mixed $value, string $message = '', string $exception = '')
1816
* @method static void validDuration(mixed $value, string $message = '', string $exception = '')
1917
* @method static void validDateTime(mixed $value, string $message = '', string $exception = '')
2018
* @method static void validNCName(mixed $value, string $message = '', string $exception = '')
2119
* @method static void validQName(mixed $value, string $message = '', string $exception = '')
22-
* @method static void nullOrValidAllowedXPathAxes(mixed $value, array $allowed_axes, string $message = '', string $exception = '')
2320
* @method static void nullOrValidAllowedXPathFilter(mixed $value, array $allowed_axes, array $allowed_functions, string $message = '', string $exception = '')
24-
* @method static void nullOrValidAllowedXPathFunctions(mixed $value, array $allowed_functions, string $message = '', string $exception = '')
2521
* @method static void nullOrValidHexBinary(mixed $value, string $message = '', string $exception = '')
2622
* @method static void nullOrValidNMToken(mixed $value, string $message = '', string $exception = '')
2723
* @method static void nullOrValidNMTokens(mixed $value, string $message = '', string $exception = '')
2824
* @method static void nullOrValidDuration(mixed $value, string $message = '', string $exception = '')
2925
* @method static void nullOrValidDateTime(mixed $value, string $message = '', string $exception = '')
3026
* @method static void nullOrValidNCName(mixed $value, string $message = '', string $exception = '')
3127
* @method static void nullOrValidQName(mixed $value, string $message = '', string $exception = '')
32-
* @method static void allValidAllowedXPathAxes(mixed $value, array $allowed_axes, string $message = '', string $exception = '')
3328
* @method static void allValidAllowedXPathFilter(mixed $value, array $allowed_axes, array $allowed_functions, string $message = '', string $exception = '')
34-
* @method static void allValidAllowedXPathFunctions(mixed $value, array $allowed_functions, string $message = '', string $exception = '')
3529
* @method static void allValidHexBinary(mixed $value, string $message = '', string $exception = '')
3630
* @method static void allValidNMToken(mixed $value, string $message = '', string $exception = '')
3731
* @method static void allValidNMTokens(mixed $value, string $message = '', string $exception = '')

‎src/Assert/XPathFilterTrait.php‎

Lines changed: 22 additions & 151 deletions
Original file line numberDiff line numberDiff line change
@@ -4,78 +4,19 @@
44

55
namespace SimpleSAML\XML\Assert;
66

7+
use InvalidArgumentException;
78
use SimpleSAML\Assert\Assert as BaseAssert;
8-
use SimpleSAML\Assert\AssertionFailedException;
99
use SimpleSAML\XML\Constants as C;
1010
use SimpleSAML\XML\Exception\RuntimeException;
11+
use SimpleSAML\XML\Utils\XPathFilter;
1112

12-
use function in_array;
13-
use function preg_match_all;
14-
use function preg_replace;
1513
use function sprintf;
1614

1715
/**
1816
* @package simplesamlphp/xml-common
1917
*/
2018
trait XPathFilterTrait
2119
{
22-
/**
23-
* Remove the content from all single or double-quoted strings in $input, leaving only quotes.
24-
* Use possessive quantifiers (i.e. *+ and ++ instead of * and + respectively) to prevent backtracking.
25-
*
26-
* '/(["\'])(?:(?!\1).)*+\1/'
27-
* (["\']) # Match a single or double quote and capture it in group 1
28-
* (?: # Start a non-capturing group
29-
* (?! # Negative lookahead
30-
* \1 # Match the same quote as in group 1
31-
* ) # End of negative lookahead
32-
* . # Match any character (that is not a quote, because of the negative lookahead)
33-
* )*+ # Repeat the non-capturing group zero or more times, possessively
34-
* \1 # Match the same quote as in group 1
35-
*/
36-
private static string $regex_xpfilter_remove_strings = '/(["\'])(?:(?!\1).)*+\1/';
37-
38-
/**
39-
* Function names are lower-case alpha (i.e. [a-z]) and can contain one or more hyphens,
40-
* but cannot start or end with a hyphen. To match this, we start with matching one or more
41-
* lower-case alpha characters, followed by zero or more atomic groups that start with a hyphen
42-
* and then match one or more lower-case alpha characters. This ensures that the function name
43-
* cannot start or end with a hyphen, but can contain one or more hyphens.
44-
* More than one consecutive hyphen does not match.
45-
*
46-
* '/([a-z]++(?>-[a-z]++)*+)\s*+\(/'
47-
* ( # Start a capturing group
48-
* [a-z]++ # Match one or more lower-case alpha characters
49-
* (?> # Start an atomic group (no capturing)
50-
* - # Match a hyphen
51-
* [a-z]++ # Match one or more lower-case alpha characters, possessively
52-
* )*+ # Repeat the atomic group zero or more times,
53-
* ) # End of the capturing group
54-
* \s*+ # Match zero or more whitespace characters, possessively
55-
* \( # Match an opening parenthesis
56-
*/
57-
private static string $regex_xpfilter_functions = '/([a-z]++(?>-[a-z]++)*+)\\s*+\\(/';
58-
59-
/**
60-
* We use the same rules for matching Axis names as we do for function names.
61-
* The only difference is that we match the '::' instead of the '('
62-
* so everything that was said about the regular expression for function names
63-
* applies here as well.
64-
*
65-
* '/([a-z]++(?>-[a-z]++)*+)\s*+::'
66-
* ( # Start a capturing group
67-
* [a-z]++ # Match one or more lower-case alpha characters
68-
* (?> # Start an atomic group (no capturing)
69-
* - # Match a hyphen
70-
* [a-z]++ # Match one or more lower-case alpha characters, possessively
71-
* )*+ # Repeat the atomic group zero or more times,
72-
* ) # End of the capturing group
73-
* \s*+ # Match zero or more whitespace characters, possessively
74-
* \( # Match an opening parenthesis
75-
*/
76-
private static string $regex_xpfilter_axes = '/([a-z]++(?>-[a-z]++)*+)\\s*+::/';
77-
78-
7920
/***********************************************************************************
8021
* NOTE: Custom assertions may be added below this line. *
8122
* They SHOULD be marked as `private` to ensure the call is forced *
@@ -89,7 +30,7 @@ trait XPathFilterTrait
8930
* The goal is preventing DoS attacks by limiting the complexity of the XPath expression by only allowing
9031
* a select subset of functions and axes.
9132
* The check uses a list of allowed functions and axes, and throws an exception when an unknown function
92-
* or axis is found in the $value.
33+
* or axis is found in the $xpathExpression.
9334
*
9435
* Limitations:
9536
* - The implementation is based on regular expressions, and does not employ an XPath 1.0 parser. It may not
@@ -102,107 +43,37 @@ trait XPathFilterTrait
10243
* XPath processor that will evaluate the expression.
10344
* - The check was written with the XPath 1.0 syntax in mind, but should work equally well for XPath 2.0 and 3.0.
10445
*
105-
* @param string $value
46+
* @param string $xpathExpression
10647
* @param array<string> $allowed_axes
10748
* @param array<string> $allowed_functions
10849
* @param string $message
10950
*/
11051
public static function validAllowedXPathFilter(
111-
string $value,
112-
array $allowed_axes = C::DEFAULT_ALLOWED_AXES,
113-
array $allowed_functions = C::DEFAULT_ALLOWED_FUNCTIONS,
52+
string $xpathExpression,
53+
array $allowedAxes = C::DEFAULT_ALLOWED_AXES,
54+
array $allowedFunctions = C::DEFAULT_ALLOWED_FUNCTIONS,
11455
string $message = '',
11556
): void {
116-
BaseAssert::allString($allowed_axes);
117-
BaseAssert::allString($allowed_functions);
57+
BaseAssert::allString($allowedAxes);
58+
BaseAssert::allString($allowedFunctions);
11859
BaseAssert::maxLength(
119-
$value,
60+
$xpathExpression,
12061
C::XPATH_FILTER_MAX_LENGTH,
12162
sprintf('XPath Filter exceeds the limit of 100 characters.'),
12263
);
12364

124-
$strippedValue = preg_replace(
125-
self::$regex_xpfilter_remove_strings,
126-
// Replace the content with two of the quotes that were matched
127-
"\\1\\1",
128-
$value,
129-
);
130-
131-
if ($strippedValue === null) {
132-
throw new RuntimeException("Error in preg_replace.");
133-
}
134-
135-
self::validAllowedXpathFunctions($strippedValue, $allowed_functions);
136-
self::validAllowedXpathAxes($strippedValue, $allowed_axes);
137-
}
138-
139-
140-
/**
141-
* @param string $value
142-
* @param array<string> $allowed_functions
143-
* @param string $message
144-
*/
145-
public static function validAllowedXPathFunctions(
146-
string $value,
147-
array $allowed_functions = C::DEFAULT_ALLOWED_FUNCTIONS,
148-
string $message = '',
149-
): void {
150-
/**
151-
* Check if the $xpath_expression uses an XPath function that is not in the list of allowed functions
152-
*
153-
* Look for the function specifier '(' and look for a function name before it.
154-
* Ignoring whitespace before the '(' and the function name.
155-
* All functions must match a string on a list of allowed function names
156-
*/
157-
$matches = [];
158-
$res = preg_match_all(self::$regex_xpfilter_functions, $value, $matches);
159-
if ($res === false) {
160-
throw new RuntimeException("Error in preg_match_all.");
161-
}
162-
163-
// Check that all the function names we found are in the list of allowed function names
164-
foreach ($matches[1] as $match) {
165-
if (!in_array($match, $allowed_functions)) {
166-
throw new AssertionFailedException(sprintf(
167-
$message ?: '\'%s\' is not an allowed XPath function.',
168-
$match,
169-
));
170-
}
171-
}
172-
}
173-
174-
175-
/**
176-
* @param string $value
177-
* @param array<string> $allowed_axes
178-
* @param string $message
179-
*/
180-
public static function validAllowedXPathAxes(
181-
string $value,
182-
array $allowed_axes = C::DEFAULT_ALLOWED_AXES,
183-
string $message = '',
184-
): void {
185-
/**
186-
* Check if the $value uses an XPath axis that is not in the list of allowed axes
187-
*
188-
* Look for the axis specifier '::' and look for a function name before it.
189-
* Ignoring whitespace before the '::' and the axis name.
190-
* All axes must match a string on a list of allowed axis names
191-
*/
192-
$matches = [];
193-
$res = preg_match_all(self::$regex_xpfilter_axes, $value, $matches);
194-
if ($res === false) {
195-
throw new RuntimeException("Error in preg_match_all.");
196-
}
197-
198-
// Check that all the axes names we found are in the list of allowed axes names
199-
foreach ($matches[1] as $match) {
200-
if (!in_array($match, $allowed_axes)) {
201-
throw new AssertionFailedException(sprintf(
202-
$message ?: '\'%s\' is not an allowed XPath axis.',
203-
$match,
204-
));
205-
}
65+
try {
66+
// First remove the contents of any string literals in the $xpath to prevent false positives
67+
$xpathWithoutStringLiterals = XPathFilter::removeStringContents($xpathExpression);
68+
69+
// Then check that the xpath expression only contains allowed functions and axes, throws when it doesn't
70+
XPathFilter::filterXPathFunction($xpathWithoutStringLiterals, $allowedFunctions);
71+
XPathFilter::filterXPathAxis($xpathWithoutStringLiterals, $allowedAxes);
72+
} catch (RuntimeException $e) {
73+
throw new InvalidArgumentException(sprintf(
74+
$message ?: $e->getMessage(),
75+
$xpathExpression,
76+
));
20677
}
20778
}
20879
}

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