| /* |
| * Copyright (C) 2011 Adam Barth. All Rights Reserved. |
| * Copyright (C) 2011 Daniel Bates (dbates@intudata.com). |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "core/html/parser/XSSAuditor.h" |
| |
| #include "core/HTMLNames.h" |
| #include "core/SVGNames.h" |
| #include "core/XLinkNames.h" |
| #include "core/dom/Document.h" |
| #include "core/frame/LocalFrame.h" |
| #include "core/frame/Settings.h" |
| #include "core/frame/csp/ContentSecurityPolicy.h" |
| #include "core/html/HTMLParamElement.h" |
| #include "core/html/LinkRelAttribute.h" |
| #include "core/html/parser/HTMLDocumentParser.h" |
| #include "core/html/parser/HTMLParserIdioms.h" |
| #include "core/html/parser/TextResourceDecoder.h" |
| #include "core/html/parser/XSSAuditorDelegate.h" |
| #include "core/inspector/ConsoleMessage.h" |
| #include "core/loader/DocumentLoader.h" |
| #include "core/loader/MixedContentChecker.h" |
| #include "platform/network/EncodedFormData.h" |
| #include "platform/text/DecodeEscapeSequences.h" |
| #include "wtf/ASCIICType.h" |
| #include "wtf/PtrUtil.h" |
| #include <memory> |
| |
| namespace { |
| |
| // SecurityOrigin::urlWithUniqueSecurityOrigin() can't be used cross-thread, or we'd use it instead. |
| const char kURLWithUniqueOrigin[] = "data:,"; |
| |
| const char kSafeJavaScriptURL[] = "javascript:void(0)"; |
| |
| } // namespace |
| |
| namespace blink { |
| |
| using namespace HTMLNames; |
| |
| static bool isNonCanonicalCharacter(UChar c) |
| { |
| // We remove all non-ASCII characters, including non-printable ASCII characters. |
| // |
| // Note, we don't remove backslashes like PHP stripslashes(), which among other things converts "\\0" to the \0 character. |
| // Instead, we remove backslashes and zeros (since the string "\\0" =(remove backslashes)=> "0"). However, this has the |
| // adverse effect that we remove any legitimate zeros from a string. |
| // |
| // We also remove forward-slash, because it is common for some servers to collapse successive path components, eg, |
| // a//b becomes a/b. |
| // |
| // We also remove the questionmark character, since some severs replace invalid high-bytes with a questionmark. We |
| // are already stripping the high-bytes so we also strip the questionmark to match. |
| // |
| // We also move the percent character, since some servers strip it when there's a malformed sequence. |
| // |
| // For instance: new String("http://localhost:8000?x") => new String("http:localhost:8x"). |
| return (c == '\\' || c == '0' || c == '\0' || c == '/' || c == '?' || c == '%' || c >= 127); |
| } |
| |
| static bool isRequiredForInjection(UChar c) |
| { |
| return (c == '\'' || c == '"' || c == '<' || c == '>'); |
| } |
| |
| static bool isTerminatingCharacter(UChar c) |
| { |
| return (c == '&' || c == '/' || c == '"' || c == '\'' || c == '<' || c == '>' || c == ','); |
| } |
| |
| static bool isHTMLQuote(UChar c) |
| { |
| return (c == '"' || c == '\''); |
| } |
| |
| static bool isJSNewline(UChar c) |
| { |
| // Per ecma-262 section 7.3 Line Terminators. |
| return (c == '\n' || c == '\r' || c == 0x2028 || c == 0x2029); |
| } |
| |
| static bool startsHTMLCommentAt(const String& string, size_t start) |
| { |
| return (start + 3 < string.length() && string[start] == '<' && string[start + 1] == '!' && string[start + 2] == '-' && string[start + 3] == '-'); |
| } |
| |
| static bool startsSingleLineCommentAt(const String& string, size_t start) |
| { |
| return (start + 1 < string.length() && string[start] == '/' && string[start + 1] == '/'); |
| } |
| |
| static bool startsMultiLineCommentAt(const String& string, size_t start) |
| { |
| return (start + 1 < string.length() && string[start] == '/' && string[start + 1] == '*'); |
| } |
| |
| static bool startsOpeningScriptTagAt(const String& string, size_t start) |
| { |
| return start + 6 < string.length() && string[start] == '<' |
| && WTF::toASCIILowerUnchecked(string[start + 1]) == 's' |
| && WTF::toASCIILowerUnchecked(string[start + 2]) == 'c' |
| && WTF::toASCIILowerUnchecked(string[start + 3]) == 'r' |
| && WTF::toASCIILowerUnchecked(string[start + 4]) == 'i' |
| && WTF::toASCIILowerUnchecked(string[start + 5]) == 'p' |
| && WTF::toASCIILowerUnchecked(string[start + 6]) == 't'; |
| } |
| |
| // If other files need this, we should move this to core/html/parser/HTMLParserIdioms.h |
| template<size_t inlineCapacity> |
| bool threadSafeMatch(const Vector<UChar, inlineCapacity>& vector, const QualifiedName& qname) |
| { |
| return equalIgnoringNullity(vector, qname.localName().impl()); |
| } |
| |
| static bool hasName(const HTMLToken& token, const QualifiedName& name) |
| { |
| return threadSafeMatch(token.name(), name); |
| } |
| |
| static bool findAttributeWithName(const HTMLToken& token, const QualifiedName& name, size_t& indexOfMatchingAttribute) |
| { |
| // Notice that we're careful not to ref the StringImpl here because we might be on a background thread. |
| const String& attrName = name.namespaceURI() == XLinkNames::xlinkNamespaceURI ? "xlink:" + name.localName().getString() : name.localName().getString(); |
| |
| for (size_t i = 0; i < token.attributes().size(); ++i) { |
| if (equalIgnoringNullity(token.attributes().at(i).nameAsVector(), attrName)) { |
| indexOfMatchingAttribute = i; |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| static bool isNameOfInlineEventHandler(const Vector<UChar, 32>& name) |
| { |
| const size_t lengthOfShortestInlineEventHandlerName = 5; // To wit: oncut. |
| if (name.size() < lengthOfShortestInlineEventHandlerName) |
| return false; |
| return name[0] == 'o' && name[1] == 'n'; |
| } |
| |
| static bool isDangerousHTTPEquiv(const String& value) |
| { |
| String equiv = value.stripWhiteSpace(); |
| return equalIgnoringCase(equiv, "refresh") || equalIgnoringCase(equiv, "set-cookie"); |
| } |
| |
| static inline String decode16BitUnicodeEscapeSequences(const String& string) |
| { |
| // Note, the encoding is ignored since each %u-escape sequence represents a UTF-16 code unit. |
| return decodeEscapeSequences<Unicode16BitEscapeSequence>(string, UTF8Encoding()); |
| } |
| |
| static inline String decodeStandardURLEscapeSequences(const String& string, const WTF::TextEncoding& encoding) |
| { |
| // We use decodeEscapeSequences() instead of decodeURLEscapeSequences() (declared in weborigin/KURL.h) to |
| // avoid platform-specific URL decoding differences (e.g. KURLGoogle). |
| return decodeEscapeSequences<URLEscapeSequence>(string, encoding); |
| } |
| |
| static String fullyDecodeString(const String& string, const WTF::TextEncoding& encoding) |
| { |
| size_t oldWorkingStringLength; |
| String workingString = string; |
| do { |
| oldWorkingStringLength = workingString.length(); |
| workingString = decode16BitUnicodeEscapeSequences(decodeStandardURLEscapeSequences(workingString, encoding)); |
| } while (workingString.length() < oldWorkingStringLength); |
| workingString.replace('+', ' '); |
| return workingString; |
| } |
| |
| static void truncateForSrcLikeAttribute(String& decodedSnippet) |
| { |
| // In HTTP URLs, characters following the first ?, #, or third slash may come from |
| // the page itself and can be merely ignored by an attacker's server when a remote |
| // script or script-like resource is requested. In DATA URLS, the payload starts at |
| // the first comma, and the the first /*, //, or <!-- may introduce a comment. Also, |
| // DATA URLs may use the same string literal tricks as with script content itself. |
| // In either case, content following this may come from the page and may be ignored |
| // when the script is executed. Also, any of these characters may now be represented |
| // by the (enlarged) set of html5 entities. |
| // For simplicity, we don't differentiate based on URL scheme, and stop at the first |
| // & (since it might be part of an entity for any of the subsequent punctuation), the |
| // first # or ?, the third slash, or the first slash, <, ', or " once a comma is seen. |
| int slashCount = 0; |
| bool commaSeen = false; |
| for (size_t currentLength = 0; currentLength < decodedSnippet.length(); ++currentLength) { |
| UChar currentChar = decodedSnippet[currentLength]; |
| if (currentChar == '&' |
| || currentChar == '?' |
| || currentChar == '#' |
| || ((currentChar == '/' || currentChar == '\\') && (commaSeen || ++slashCount > 2)) |
| || (currentChar == '<' && commaSeen) |
| || (currentChar == '\'' && commaSeen) |
| || (currentChar == '"' && commaSeen)) { |
| decodedSnippet.truncate(currentLength); |
| return; |
| } |
| if (currentChar == ',') |
| commaSeen = true; |
| } |
| } |
| |
| static void truncateForScriptLikeAttribute(String& decodedSnippet) |
| { |
| // Beware of trailing characters which came from the page itself, not the |
| // injected vector. Excluding the terminating character covers common cases |
| // where the page immediately ends the attribute, but doesn't cover more |
| // complex cases where there is other page data following the injection. |
| // Generally, these won't parse as javascript, so the injected vector |
| // typically excludes them from consideration via a single-line comment or |
| // by enclosing them in a string literal terminated later by the page's own |
| // closing punctuation. Since the snippet has not been parsed, the vector |
| // may also try to introduce these via entities. As a result, we'd like to |
| // stop before the first "//", the first <!--, the first entity, or the first |
| // quote not immediately following the first equals sign (taking whitespace |
| // into consideration). To keep things simpler, we don't try to distinguish |
| // between entity-introducing amperands vs. other uses, nor do we bother to |
| // check for a second slash for a comment, nor do we bother to check for |
| // !-- following a less-than sign. We stop instead on any ampersand |
| // slash, or less-than sign. |
| size_t position = 0; |
| if ((position = decodedSnippet.find("=")) != kNotFound |
| && (position = decodedSnippet.find(isNotHTMLSpace<UChar>, position + 1)) != kNotFound |
| && (position = decodedSnippet.find(isTerminatingCharacter, isHTMLQuote(decodedSnippet[position]) ? position + 1 : position)) != kNotFound) { |
| decodedSnippet.truncate(position); |
| } |
| } |
| |
| static ReflectedXSSDisposition combineXSSProtectionHeaderAndCSP(ReflectedXSSDisposition xssProtection, ReflectedXSSDisposition reflectedXSS) |
| { |
| ReflectedXSSDisposition result = std::max(xssProtection, reflectedXSS); |
| |
| if (result == ReflectedXSSInvalid || result == FilterReflectedXSS || result == ReflectedXSSUnset) |
| return FilterReflectedXSS; |
| |
| return result; |
| } |
| |
| static bool isSemicolonSeparatedAttribute(const HTMLToken::Attribute& attribute) |
| { |
| return threadSafeMatch(attribute.nameAsVector(), SVGNames::valuesAttr); |
| } |
| |
| static String semicolonSeparatedValueContainingJavaScriptURL(const String& value) |
| { |
| Vector<String> valueList; |
| value.split(';', valueList); |
| for (size_t i = 0; i < valueList.size(); ++i) { |
| String stripped = stripLeadingAndTrailingHTMLSpaces(valueList[i]); |
| if (protocolIsJavaScript(stripped)) |
| return stripped; |
| } |
| return emptyString(); |
| } |
| |
| XSSAuditor::XSSAuditor() |
| : m_isEnabled(false) |
| , m_xssProtection(FilterReflectedXSS) |
| , m_didSendValidCSPHeader(false) |
| , m_didSendValidXSSProtectionHeader(false) |
| , m_state(Uninitialized) |
| , m_scriptTagFoundInRequest(false) |
| , m_scriptTagNestingLevel(0) |
| , m_encoding(UTF8Encoding()) |
| { |
| // Although tempting to call init() at this point, the various objects |
| // we want to reference might not all have been constructed yet. |
| } |
| |
| void XSSAuditor::initForFragment() |
| { |
| ASSERT(isMainThread()); |
| ASSERT(m_state == Uninitialized); |
| m_state = FilteringTokens; |
| // When parsing a fragment, we don't enable the XSS auditor because it's |
| // too much overhead. |
| ASSERT(!m_isEnabled); |
| } |
| |
| void XSSAuditor::init(Document* document, XSSAuditorDelegate* auditorDelegate) |
| { |
| ASSERT(isMainThread()); |
| if (m_state != Uninitialized) |
| return; |
| m_state = FilteringTokens; |
| |
| if (Settings* settings = document->settings()) |
| m_isEnabled = settings->xssAuditorEnabled(); |
| |
| if (!m_isEnabled) |
| return; |
| |
| m_documentURL = document->url().copy(); |
| |
| // In theory, the Document could have detached from the LocalFrame after the |
| // XSSAuditor was constructed. |
| if (!document->frame()) { |
| m_isEnabled = false; |
| return; |
| } |
| |
| if (m_documentURL.isEmpty()) { |
| // The URL can be empty when opening a new browser window or calling window.open(""). |
| m_isEnabled = false; |
| return; |
| } |
| |
| if (m_documentURL.protocolIsData()) { |
| m_isEnabled = false; |
| return; |
| } |
| |
| if (document->encoding().isValid()) |
| m_encoding = document->encoding(); |
| |
| if (DocumentLoader* documentLoader = document->frame()->loader().documentLoader()) { |
| const AtomicString& headerValue = documentLoader->response().httpHeaderField(HTTPNames::X_XSS_Protection); |
| String errorDetails; |
| unsigned errorPosition = 0; |
| String reportURL; |
| KURL xssProtectionReportURL; |
| |
| // Process the X-XSS-Protection header, then mix in the CSP header's value. |
| ReflectedXSSDisposition xssProtectionHeader = parseXSSProtectionHeader(headerValue, errorDetails, errorPosition, reportURL); |
| m_didSendValidXSSProtectionHeader = xssProtectionHeader != ReflectedXSSUnset && xssProtectionHeader != ReflectedXSSInvalid; |
| if ((xssProtectionHeader == FilterReflectedXSS || xssProtectionHeader == BlockReflectedXSS) && !reportURL.isEmpty()) { |
| xssProtectionReportURL = document->completeURL(reportURL); |
| if (MixedContentChecker::isMixedContent(document->getSecurityOrigin(), xssProtectionReportURL)) { |
| errorDetails = "insecure reporting URL for secure page"; |
| xssProtectionHeader = ReflectedXSSInvalid; |
| xssProtectionReportURL = KURL(); |
| } |
| } |
| if (xssProtectionHeader == ReflectedXSSInvalid) |
| document->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Error parsing header X-XSS-Protection: " + headerValue + ": " + errorDetails + " at character position " + String::format("%u", errorPosition) + ". The default protections will be applied.")); |
| |
| ReflectedXSSDisposition cspHeader = document->contentSecurityPolicy()->getReflectedXSSDisposition(); |
| m_didSendValidCSPHeader = cspHeader != ReflectedXSSUnset && cspHeader != ReflectedXSSInvalid; |
| |
| m_xssProtection = combineXSSProtectionHeaderAndCSP(xssProtectionHeader, cspHeader); |
| // FIXME: Combine the two report URLs in some reasonable way. |
| if (auditorDelegate) |
| auditorDelegate->setReportURL(xssProtectionReportURL.copy()); |
| |
| EncodedFormData* httpBody = documentLoader->request().httpBody(); |
| if (httpBody && !httpBody->isEmpty()) |
| m_httpBodyAsString = httpBody->flattenToString(); |
| } |
| |
| setEncoding(m_encoding); |
| } |
| |
| void XSSAuditor::setEncoding(const WTF::TextEncoding& encoding) |
| { |
| const size_t miniumLengthForSuffixTree = 512; // FIXME: Tune this parameter. |
| const int suffixTreeDepth = 5; |
| |
| if (!encoding.isValid()) |
| return; |
| |
| m_encoding = encoding; |
| |
| m_decodedURL = canonicalize(m_documentURL.getString(), NoTruncation); |
| if (m_decodedURL.find(isRequiredForInjection) == kNotFound) |
| m_decodedURL = String(); |
| |
| if (!m_httpBodyAsString.isEmpty()) { |
| m_decodedHTTPBody = canonicalize(m_httpBodyAsString, NoTruncation); |
| m_httpBodyAsString = String(); |
| if (m_decodedHTTPBody.find(isRequiredForInjection) == kNotFound) |
| m_decodedHTTPBody = String(); |
| if (m_decodedHTTPBody.length() >= miniumLengthForSuffixTree) |
| m_decodedHTTPBodySuffixTree = wrapUnique(new SuffixTree<ASCIICodebook>(m_decodedHTTPBody, suffixTreeDepth)); |
| } |
| |
| if (m_decodedURL.isEmpty() && m_decodedHTTPBody.isEmpty()) |
| m_isEnabled = false; |
| } |
| |
| std::unique_ptr<XSSInfo> XSSAuditor::filterToken(const FilterTokenRequest& request) |
| { |
| ASSERT(m_state != Uninitialized); |
| if (!m_isEnabled || m_xssProtection == AllowReflectedXSS) |
| return nullptr; |
| |
| bool didBlockScript = false; |
| if (request.token.type() == HTMLToken::StartTag) |
| didBlockScript = filterStartToken(request); |
| else if (m_scriptTagNestingLevel) { |
| if (request.token.type() == HTMLToken::Character) |
| didBlockScript = filterCharacterToken(request); |
| else if (request.token.type() == HTMLToken::EndTag) |
| filterEndToken(request); |
| } |
| |
| if (didBlockScript) { |
| bool didBlockEntirePage = (m_xssProtection == BlockReflectedXSS); |
| std::unique_ptr<XSSInfo> xssInfo = XSSInfo::create(m_documentURL, didBlockEntirePage, m_didSendValidXSSProtectionHeader, m_didSendValidCSPHeader); |
| return xssInfo; |
| } |
| return nullptr; |
| } |
| |
| bool XSSAuditor::filterStartToken(const FilterTokenRequest& request) |
| { |
| m_state = FilteringTokens; |
| bool didBlockScript = eraseDangerousAttributesIfInjected(request); |
| |
| if (hasName(request.token, scriptTag)) { |
| didBlockScript |= filterScriptToken(request); |
| ASSERT(request.shouldAllowCDATA || !m_scriptTagNestingLevel); |
| m_scriptTagNestingLevel++; |
| } else if (hasName(request.token, objectTag)) |
| didBlockScript |= filterObjectToken(request); |
| else if (hasName(request.token, paramTag)) |
| didBlockScript |= filterParamToken(request); |
| else if (hasName(request.token, embedTag)) |
| didBlockScript |= filterEmbedToken(request); |
| else if (hasName(request.token, iframeTag) || hasName(request.token, frameTag)) |
| didBlockScript |= filterFrameToken(request); |
| else if (hasName(request.token, metaTag)) |
| didBlockScript |= filterMetaToken(request); |
| else if (hasName(request.token, baseTag)) |
| didBlockScript |= filterBaseToken(request); |
| else if (hasName(request.token, formTag)) |
| didBlockScript |= filterFormToken(request); |
| else if (hasName(request.token, inputTag)) |
| didBlockScript |= filterInputToken(request); |
| else if (hasName(request.token, buttonTag)) |
| didBlockScript |= filterButtonToken(request); |
| else if (hasName(request.token, linkTag)) |
| didBlockScript |= filterLinkToken(request); |
| |
| return didBlockScript; |
| } |
| |
| void XSSAuditor::filterEndToken(const FilterTokenRequest& request) |
| { |
| ASSERT(m_scriptTagNestingLevel); |
| m_state = FilteringTokens; |
| if (hasName(request.token, scriptTag)) { |
| m_scriptTagNestingLevel--; |
| ASSERT(request.shouldAllowCDATA || !m_scriptTagNestingLevel); |
| } |
| } |
| |
| bool XSSAuditor::filterCharacterToken(const FilterTokenRequest& request) |
| { |
| ASSERT(m_scriptTagNestingLevel); |
| ASSERT(m_state != Uninitialized); |
| if (m_state == PermittingAdjacentCharacterTokens) |
| return false; |
| |
| if (m_state == FilteringTokens && m_scriptTagFoundInRequest) { |
| String snippet = canonicalizedSnippetForJavaScript(request); |
| if (isContainedInRequest(snippet)) |
| m_state = SuppressingAdjacentCharacterTokens; |
| else if (!snippet.isEmpty()) |
| m_state = PermittingAdjacentCharacterTokens; |
| } |
| if (m_state == SuppressingAdjacentCharacterTokens) { |
| request.token.eraseCharacters(); |
| request.token.appendToCharacter(' '); // Technically, character tokens can't be empty. |
| return true; |
| } |
| return false; |
| } |
| |
| bool XSSAuditor::filterScriptToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, scriptTag)); |
| |
| bool didBlockScript = false; |
| m_scriptTagFoundInRequest = isContainedInRequest(canonicalizedSnippetForTagName(request)); |
| if (m_scriptTagFoundInRequest) { |
| didBlockScript |= eraseAttributeIfInjected(request, srcAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| didBlockScript |= eraseAttributeIfInjected(request, SVGNames::hrefAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| didBlockScript |= eraseAttributeIfInjected(request, XLinkNames::hrefAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| } |
| return didBlockScript; |
| } |
| |
| bool XSSAuditor::filterObjectToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, objectTag)); |
| |
| bool didBlockScript = false; |
| if (isContainedInRequest(canonicalizedSnippetForTagName(request))) { |
| didBlockScript |= eraseAttributeIfInjected(request, dataAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| didBlockScript |= eraseAttributeIfInjected(request, typeAttr); |
| didBlockScript |= eraseAttributeIfInjected(request, classidAttr); |
| } |
| return didBlockScript; |
| } |
| |
| bool XSSAuditor::filterParamToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, paramTag)); |
| |
| size_t indexOfNameAttribute; |
| if (!findAttributeWithName(request.token, nameAttr, indexOfNameAttribute)) |
| return false; |
| |
| const HTMLToken::Attribute& nameAttribute = request.token.attributes().at(indexOfNameAttribute); |
| if (!HTMLParamElement::isURLParameter(nameAttribute.value())) |
| return false; |
| |
| return eraseAttributeIfInjected(request, valueAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| } |
| |
| bool XSSAuditor::filterEmbedToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, embedTag)); |
| |
| bool didBlockScript = false; |
| if (isContainedInRequest(canonicalizedSnippetForTagName(request))) { |
| didBlockScript |= eraseAttributeIfInjected(request, codeAttr, String(), SrcLikeAttributeTruncation); |
| didBlockScript |= eraseAttributeIfInjected(request, srcAttr, blankURL().getString(), SrcLikeAttributeTruncation); |
| didBlockScript |= eraseAttributeIfInjected(request, typeAttr); |
| } |
| return didBlockScript; |
| } |
| |
| bool XSSAuditor::filterFrameToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, iframeTag) || hasName(request.token, frameTag)); |
| |
| bool didBlockScript = eraseAttributeIfInjected(request, srcdocAttr, String(), ScriptLikeAttributeTruncation); |
| if (isContainedInRequest(canonicalizedSnippetForTagName(request))) |
| didBlockScript |= eraseAttributeIfInjected(request, srcAttr, String(), SrcLikeAttributeTruncation); |
| |
| return didBlockScript; |
| } |
| |
| bool XSSAuditor::filterMetaToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, metaTag)); |
| |
| return eraseAttributeIfInjected(request, http_equivAttr); |
| } |
| |
| bool XSSAuditor::filterBaseToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, baseTag)); |
| |
| return eraseAttributeIfInjected(request, hrefAttr, String(), SrcLikeAttributeTruncation); |
| } |
| |
| bool XSSAuditor::filterFormToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, formTag)); |
| |
| return eraseAttributeIfInjected(request, actionAttr, kURLWithUniqueOrigin); |
| } |
| |
| bool XSSAuditor::filterInputToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, inputTag)); |
| |
| return eraseAttributeIfInjected(request, formactionAttr, kURLWithUniqueOrigin, SrcLikeAttributeTruncation); |
| } |
| |
| bool XSSAuditor::filterButtonToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, buttonTag)); |
| |
| return eraseAttributeIfInjected(request, formactionAttr, kURLWithUniqueOrigin, SrcLikeAttributeTruncation); |
| } |
| |
| bool XSSAuditor::filterLinkToken(const FilterTokenRequest& request) |
| { |
| ASSERT(request.token.type() == HTMLToken::StartTag); |
| ASSERT(hasName(request.token, linkTag)); |
| |
| size_t indexOfAttribute = 0; |
| if (!findAttributeWithName(request.token, relAttr, indexOfAttribute)) |
| return false; |
| |
| const HTMLToken::Attribute& attribute = request.token.attributes().at(indexOfAttribute); |
| LinkRelAttribute parsedAttribute(attribute.value()); |
| if (!parsedAttribute.isImport()) |
| return false; |
| |
| return eraseAttributeIfInjected(request, hrefAttr, kURLWithUniqueOrigin, SrcLikeAttributeTruncation, AllowSameOriginHref); |
| } |
| |
| bool XSSAuditor::eraseDangerousAttributesIfInjected(const FilterTokenRequest& request) |
| { |
| bool didBlockScript = false; |
| for (size_t i = 0; i < request.token.attributes().size(); ++i) { |
| bool eraseAttribute = false; |
| bool valueContainsJavaScriptURL = false; |
| const HTMLToken::Attribute& attribute = request.token.attributes().at(i); |
| // FIXME: Don't create a new String for every attribute.value in the document. |
| if (isNameOfInlineEventHandler(attribute.nameAsVector())) { |
| eraseAttribute = isContainedInRequest(canonicalize(snippetFromAttribute(request, attribute), ScriptLikeAttributeTruncation)); |
| } else if (isSemicolonSeparatedAttribute(attribute)) { |
| String subValue = semicolonSeparatedValueContainingJavaScriptURL(attribute.value()); |
| if (!subValue.isEmpty()) { |
| valueContainsJavaScriptURL = true; |
| eraseAttribute = isContainedInRequest(canonicalize(nameFromAttribute(request, attribute), NoTruncation)) |
| && isContainedInRequest(canonicalize(subValue, ScriptLikeAttributeTruncation)); |
| } |
| } else if (protocolIsJavaScript(stripLeadingAndTrailingHTMLSpaces(attribute.value()))) { |
| valueContainsJavaScriptURL = true; |
| eraseAttribute = isContainedInRequest(canonicalize(snippetFromAttribute(request, attribute), ScriptLikeAttributeTruncation)); |
| } |
| if (!eraseAttribute) |
| continue; |
| request.token.eraseValueOfAttribute(i); |
| if (valueContainsJavaScriptURL) |
| request.token.appendToAttributeValue(i, kSafeJavaScriptURL); |
| didBlockScript = true; |
| } |
| return didBlockScript; |
| } |
| |
| bool XSSAuditor::eraseAttributeIfInjected(const FilterTokenRequest& request, const QualifiedName& attributeName, const String& replacementValue, TruncationKind treatment, HrefRestriction restriction) |
| { |
| size_t indexOfAttribute = 0; |
| if (!findAttributeWithName(request.token, attributeName, indexOfAttribute)) |
| return false; |
| |
| const HTMLToken::Attribute& attribute = request.token.attributes().at(indexOfAttribute); |
| if (!isContainedInRequest(canonicalize(snippetFromAttribute(request, attribute), treatment))) |
| return false; |
| |
| if (threadSafeMatch(attributeName, srcAttr) || (restriction == AllowSameOriginHref && threadSafeMatch(attributeName, hrefAttr))) { |
| if (isLikelySafeResource(attribute.value())) |
| return false; |
| } else if (threadSafeMatch(attributeName, http_equivAttr)) { |
| if (!isDangerousHTTPEquiv(attribute.value())) |
| return false; |
| } |
| |
| request.token.eraseValueOfAttribute(indexOfAttribute); |
| if (!replacementValue.isEmpty()) |
| request.token.appendToAttributeValue(indexOfAttribute, replacementValue); |
| |
| return true; |
| } |
| |
| String XSSAuditor::canonicalizedSnippetForTagName(const FilterTokenRequest& request) |
| { |
| // Grab a fixed number of characters equal to the length of the token's name plus one (to account for the "<"). |
| return canonicalize(request.sourceTracker.sourceForToken(request.token).substring(0, request.token.name().size() + 1), NoTruncation); |
| } |
| |
| String XSSAuditor::nameFromAttribute(const FilterTokenRequest& request, const HTMLToken::Attribute& attribute) |
| { |
| // The range inlcudes the character which terminates the name. So, |
| // for an input of |name="value"|, the snippet is |name=|. |
| int start = attribute.nameRange().start - request.token.startIndex(); |
| int end = attribute.valueRange().start - request.token.startIndex(); |
| return request.sourceTracker.sourceForToken(request.token).substring(start, end - start); |
| } |
| |
| String XSSAuditor::snippetFromAttribute(const FilterTokenRequest& request, const HTMLToken::Attribute& attribute) |
| { |
| // The range doesn't include the character which terminates the value. So, |
| // for an input of |name="value"|, the snippet is |name="value|. For an |
| // unquoted input of |name=value |, the snippet is |name=value|. |
| // FIXME: We should grab one character before the name also. |
| int start = attribute.nameRange().start - request.token.startIndex(); |
| int end = attribute.valueRange().end - request.token.startIndex(); |
| return request.sourceTracker.sourceForToken(request.token).substring(start, end - start); |
| } |
| |
| String XSSAuditor::canonicalize(String snippet, TruncationKind treatment) |
| { |
| String decodedSnippet = fullyDecodeString(snippet, m_encoding); |
| |
| if (treatment != NoTruncation) { |
| if (decodedSnippet.length() > kMaximumFragmentLengthTarget) { |
| // Let the page influence the stopping point to avoid disclosing leading fragments. |
| // Stop when we hit whitespace, since that is unlikely to be part a leading fragment. |
| size_t position = kMaximumFragmentLengthTarget; |
| while (position < decodedSnippet.length() && !isHTMLSpace(decodedSnippet[position])) |
| ++position; |
| decodedSnippet.truncate(position); |
| } |
| if (treatment == SrcLikeAttributeTruncation) |
| truncateForSrcLikeAttribute(decodedSnippet); |
| else if (treatment == ScriptLikeAttributeTruncation) |
| truncateForScriptLikeAttribute(decodedSnippet); |
| } |
| |
| return decodedSnippet.removeCharacters(&isNonCanonicalCharacter); |
| } |
| |
| String XSSAuditor::canonicalizedSnippetForJavaScript(const FilterTokenRequest& request) |
| { |
| String string = request.sourceTracker.sourceForToken(request.token); |
| size_t startPosition = 0; |
| size_t endPosition = string.length(); |
| size_t foundPosition = kNotFound; |
| size_t lastNonSpacePosition = kNotFound; |
| |
| // Skip over initial comments to find start of code. |
| while (startPosition < endPosition) { |
| while (startPosition < endPosition && isHTMLSpace<UChar>(string[startPosition])) |
| startPosition++; |
| |
| // Under SVG/XML rules, only HTML comment syntax matters and the parser returns |
| // these as a separate comment tokens. Having consumed whitespace, we need not look |
| // further for these. |
| if (request.shouldAllowCDATA) |
| break; |
| |
| // Under HTML rules, both the HTML and JS comment synatx matters, and the HTML |
| // comment ends at the end of the line, not with -->. |
| if (startsHTMLCommentAt(string, startPosition) || startsSingleLineCommentAt(string, startPosition)) { |
| while (startPosition < endPosition && !isJSNewline(string[startPosition])) |
| startPosition++; |
| } else if (startsMultiLineCommentAt(string, startPosition)) { |
| if (startPosition + 2 < endPosition && (foundPosition = string.find("*/", startPosition + 2)) != kNotFound) |
| startPosition = foundPosition + 2; |
| else |
| startPosition = endPosition; |
| } else |
| break; |
| } |
| |
| String result; |
| while (startPosition < endPosition && !result.length()) { |
| // Stop at next comment (using the same rules as above for SVG/XML vs HTML), when we encounter a comma, |
| // when we encoutner a backtick, when we hit an opening <script> tag, or when we exceed the maximum length |
| // target. The comma rule covers a common parameter concatenation case performed by some web servers. The |
| // backtick rule covers the ECMA6 multi-line template string feature. |
| lastNonSpacePosition = kNotFound; |
| for (foundPosition = startPosition; foundPosition < endPosition; foundPosition++) { |
| if (!request.shouldAllowCDATA) { |
| if (startsSingleLineCommentAt(string, foundPosition) |
| || startsMultiLineCommentAt(string, foundPosition) |
| || startsHTMLCommentAt(string, foundPosition)) { |
| break; |
| } |
| } |
| if (string[foundPosition] == ',' || string[foundPosition] == '`') |
| break; |
| |
| if (lastNonSpacePosition != kNotFound && startsOpeningScriptTagAt(string, foundPosition)) { |
| foundPosition = lastNonSpacePosition + 1; |
| break; |
| } |
| if (foundPosition > startPosition + kMaximumFragmentLengthTarget) { |
| // After hitting the length target, we can only stop at a point where we know we are |
| // not in the middle of a %-escape sequence. For the sake of simplicity, approximate |
| // not stopping inside a (possibly multiply encoded) %-escape sequence by breaking on |
| // whitespace only. We should have enough text in these cases to avoid false positives. |
| if (isHTMLSpace<UChar>(string[foundPosition])) |
| break; |
| } |
| if (!isHTMLSpace<UChar>(string[foundPosition])) |
| lastNonSpacePosition = foundPosition; |
| } |
| result = canonicalize(string.substring(startPosition, foundPosition - startPosition), NoTruncation); |
| startPosition = foundPosition + 1; |
| } |
| |
| return result; |
| } |
| |
| bool XSSAuditor::isContainedInRequest(const String& decodedSnippet) |
| { |
| if (decodedSnippet.isEmpty()) |
| return false; |
| if (m_decodedURL.find(decodedSnippet, 0, TextCaseInsensitive) != kNotFound) |
| return true; |
| if (m_decodedHTTPBodySuffixTree && !m_decodedHTTPBodySuffixTree->mightContain(decodedSnippet)) |
| return false; |
| return m_decodedHTTPBody.find(decodedSnippet, 0, TextCaseInsensitive) != kNotFound; |
| } |
| |
| bool XSSAuditor::isLikelySafeResource(const String& url) |
| { |
| // Give empty URLs and about:blank a pass. Making a resourceURL from an |
| // empty string below will likely later fail the "no query args test" as |
| // it inherits the document's query args. |
| if (url.isEmpty() || url == blankURL().getString()) |
| return true; |
| |
| // If the resource is loaded from the same host as the enclosing page, it's |
| // probably not an XSS attack, so we reduce false positives by allowing the |
| // request, ignoring scheme and port considerations. If the resource has a |
| // query string, we're more suspicious, however, because that's pretty rare |
| // and the attacker might be able to trick a server-side script into doing |
| // something dangerous with the query string. |
| if (m_documentURL.host().isEmpty()) |
| return false; |
| |
| KURL resourceURL(m_documentURL, url); |
| return (m_documentURL.host() == resourceURL.host() && resourceURL.query().isEmpty()); |
| } |
| |
| bool XSSAuditor::isSafeToSendToAnotherThread() const |
| { |
| return m_documentURL.isSafeToSendToAnotherThread() |
| && m_decodedURL.isSafeToSendToAnotherThread() |
| && m_decodedHTTPBody.isSafeToSendToAnotherThread() |
| && m_httpBodyAsString.isSafeToSendToAnotherThread(); |
| } |
| |
| } // namespace blink |
