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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsTreeSanitizer_h_
#define nsTreeSanitizer_h_
#include "nsAtom.h"
#include "nsHashKeys.h"
#include "nsHashtablesFwd.h"
#include "nsIPrincipal.h"
#include "nsTArray.h"
#include "nsTHashSet.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/dom/NameSpaceConstants.h"
#include "mozilla/dom/SanitizerBinding.h"
class nsIContent;
class nsIGlobalObject;
class nsINode;
namespace mozilla {
class DeclarationBlock;
enum class StyleSanitizationKind : uint8_t;
} // namespace mozilla
namespace mozilla::dom {
class DocumentFragment;
class Element;
} // namespace mozilla::dom
/**
* See the documentation of nsIParserUtils::sanitize for documentation
* about the default behavior and the configuration options of this sanitizer.
*/
class nsTreeSanitizer {
public:
/**
* The constructor.
*
* @param aFlags Flags from nsIParserUtils
*/
explicit nsTreeSanitizer(uint32_t aFlags = 0);
static void InitializeStatics();
static void ReleaseStatics();
/**
* Sanitizes a disconnected DOM fragment freshly obtained from a parser.
* The fragment must have just come from a parser so that it can't have
* mutation event listeners set on it.
*/
void Sanitize(mozilla::dom::DocumentFragment* aFragment);
/**
* Sanitizes a disconnected (not in a docshell) document freshly obtained
* from a parser. The document must not be embedded in a docshell and must
* not have had a chance to get mutation event listeners attached to it.
* The root element must be <html>.
*/
void Sanitize(mozilla::dom::Document* aDocument);
/**
* Provides additional options for usage from the Web Sanitizer API
* which allows modifying the allow-list from above
*/
void WithWebSanitizerOptions(nsIGlobalObject* aGlobal,
const mozilla::dom::SanitizerConfig& aOptions);
/**
* Removes conditional CSS from this subtree.
*/
static void RemoveConditionalCSSFromSubtree(nsINode* aRoot);
private:
/**
* Whether <style> and style="" are allowed.
*/
bool mAllowStyles;
/**
* Whether comment nodes are allowed.
*/
bool mAllowComments;
/**
* Whether HTML <font>, <center>, bgcolor="", etc., are dropped.
*/
bool mDropNonCSSPresentation;
/**
* Whether to remove forms and form controls (excluding fieldset/legend).
*/
bool mDropForms;
/**
* Whether only cid: embeds are allowed.
*/
bool mCidEmbedsOnly;
/**
* Whether to drop <img>, <video>, <audio> and <svg>.
*/
bool mDropMedia;
/**
* Whether we are sanitizing a full document (as opposed to a fragment).
*/
bool mFullDocument;
/**
* Whether we should notify to the console for anything that's stripped.
*/
bool mLogRemovals;
// WindowID used for logging removals.
uint64_t mInnerWindowID = 0;
/**
* We have various tables of static atoms for elements and attributes.
*/
class AtomsTable : public nsTHashSet<const nsStaticAtom*> {
public:
explicit AtomsTable(uint32_t aLength)
: nsTHashSet<const nsStaticAtom*>(aLength) {}
bool Contains(nsAtom* aAtom) {
// Because this table only contains static atoms, if aAtom isn't
// static we can immediately fail.
return aAtom->IsStatic() && GetEntry(aAtom->AsStatic());
}
};
// The name of an element combined with its namespace.
class ElementName : public PLDHashEntryHdr {
public:
using KeyType = const ElementName&;
using KeyTypePointer = const ElementName*;
explicit ElementName(KeyTypePointer aKey)
: mNamespaceID(aKey->mNamespaceID), mLocalName(aKey->mLocalName) {}
ElementName(int32_t aNamespaceID, RefPtr<nsAtom> aLocalName)
: mNamespaceID(aNamespaceID), mLocalName(std::move(aLocalName)) {}
ElementName(ElementName&&) = default;
~ElementName() = default;
bool KeyEquals(KeyTypePointer aKey) const {
return mNamespaceID == aKey->mNamespaceID &&
mLocalName == aKey->mLocalName;
}
static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
static PLDHashNumber HashKey(KeyTypePointer aKey) {
if (!aKey) {
return 0;
}
return mozilla::HashGeneric(aKey->mNamespaceID, aKey->mLocalName.get());
}
enum { ALLOW_MEMMOVE = true };
private:
int32_t mNamespaceID = kNameSpaceID_None;
RefPtr<nsAtom> mLocalName;
};
using ElementNameSet = nsTHashSet<ElementName>;
using ElementToAttributeSetTable =
nsTHashMap<RefPtr<nsAtom>, mozilla::UniquePtr<ElementNameSet>>;
void SanitizeChildren(nsINode* aRoot);
/**
* Queries if an element must be replaced with its children.
* @param aNamespace the namespace of the element the question is about
* @param aLocal the local name of the element the question is about
* @return true if the element must be replaced with its children and
* false if the element is to be kept
*/
bool MustFlatten(int32_t aNamespace, nsAtom* aLocal);
bool MustFlattenForSanitizerAPI(int32_t aNamespace, nsAtom* aLocal);
/**
* Queries if an element including its children must be removed.
* @param aNamespace the namespace of the element the question is about
* @param aLocal the local name of the element the question is about
* @param aElement the element node itself for inspecting attributes
* @return true if the element and its children must be removed and
* false if the element is to be kept
*/
bool MustPrune(int32_t aNamespace, nsAtom* aLocal,
mozilla::dom::Element* aElement);
bool MustPruneForSanitizerAPI(int32_t aNamespace, nsAtom* aLocal,
mozilla::dom::Element* aElement);
/**
* Checks if a given local name (for an attribute) is on the given list
* of URL attribute names.
* @param aURLs the list of URL attribute names
* @param aLocalName the name to search on the list
* @return true if aLocalName is on the aURLs list and false otherwise
*/
bool IsURL(const nsStaticAtom* const* aURLs, nsAtom* aLocalName);
/**
* Struct for what attributes and their values are allowed.
*/
struct AllowedAttributes {
// The whitelist of permitted local names to use.
AtomsTable* mNames = nullptr;
// The local names of URL-valued attributes for URL checking.
const nsStaticAtom* const* mURLs = nullptr;
// Whether XLink attributes are allowed.
bool mXLink = false;
// Whether the style attribute is allowed.
bool mStyle = false;
// Whether to leave the value of the src attribute unsanitized.
bool mDangerousSrc = false;
};
/**
* Removes dangerous attributes from the element. If the style attribute
* is allowed, its value is sanitized. The values of URL attributes are
* sanitized, except src isn't sanitized when it is allowed to remain
* potentially dangerous.
*
* @param aElement the element whose attributes should be sanitized
* @param aAllowed options for sanitizing attributes
*/
void SanitizeAttributes(mozilla::dom::Element* aElement,
AllowedAttributes aAllowed);
// Currently only used for the Sanitizer API.
bool MustDropAttribute(mozilla::dom::Element* aElement,
int32_t aAttrNamespace, nsAtom* aAttrLocalName);
bool MustDropFunkyAttribute(mozilla::dom::Element* aElement,
int32_t aAttrNamespace, nsAtom* aAttrLocalName);
/**
* Remove the named URL attribute from the element if the URL fails a
* security check.
*
* @param aElement the element whose attribute to possibly modify
* @param aNamespace the namespace of the URL attribute
* @param aLocalName the local name of the URL attribute
* @param aFragmentsOnly allows same-document references only
* @return true if the attribute was removed and false otherwise
*/
bool SanitizeURL(mozilla::dom::Element* aElement, int32_t aNamespace,
nsAtom* aLocalName, bool aFragmentsOnly = false);
/**
* Checks a style rule for the presence of the 'binding' CSS property and
* removes that property from the rule.
*
* @param aDeclaration The style declaration to check
* @return true if the rule was modified and false otherwise
*/
bool SanitizeStyleDeclaration(mozilla::DeclarationBlock* aDeclaration);
/**
* Sanitizes an inline style element (an HTML or SVG <style>).
*
* Returns whether the style has changed.
*/
static bool SanitizeInlineStyle(mozilla::dom::Element*,
mozilla::StyleSanitizationKind);
/**
* Removes all attributes from an element node.
*/
static void RemoveAllAttributes(mozilla::dom::Element* aElement);
/**
* Removes all attributes from the descendants of an element but not from
* the element itself.
*/
static void RemoveAllAttributesFromDescendants(mozilla::dom::Element*);
static bool MatchesElementName(ElementNameSet& aNames, int32_t aNamespace,
nsAtom* aLocalName);
static bool MatchesAttributeMatchList(ElementToAttributeSetTable& aMatchList,
mozilla::dom::Element& aElement,
int32_t aAttrNamespace,
nsAtom* aAttrLocalName);
static mozilla::UniquePtr<ElementNameSet> ConvertElementNames(
const mozilla::dom::Sequence<nsString>& aNames);
/**
* Log a Console Service message to indicate we removed something.
* If you pass an element and/or attribute, their information will
* be appended to the message.
*
* @param aMessage the basic message to log.
* @param aDocument the base document we're modifying
* (used for the error message)
* @param aElement optional, the element being removed or modified.
* @param aAttribute optional, the attribute being removed or modified.
*/
void LogMessage(const char* aMessage, mozilla::dom::Document* aDoc,
mozilla::dom::Element* aElement = nullptr,
nsAtom* aAttr = nullptr);
/**
* The whitelist of HTML elements.
*/
static AtomsTable* sElementsHTML;
/**
* The whitelist of non-presentational HTML attributes.
*/
static AtomsTable* sAttributesHTML;
/**
* The whitelist of presentational HTML attributes.
*/
static AtomsTable* sPresAttributesHTML;
/**
* The whitelist of SVG elements.
*/
static AtomsTable* sElementsSVG;
/**
* The whitelist of SVG attributes.
*/
static AtomsTable* sAttributesSVG;
/**
* The whitelist of SVG elements.
*/
static AtomsTable* sElementsMathML;
/**
* The whitelist of MathML attributes.
*/
static AtomsTable* sAttributesMathML;
/**
* The built-in baseline attribute allow list used by the Sanitizer API.
*/
static AtomsTable* sBaselineAttributeAllowlist;
/**
* The built-in baseline element allow list used by the Sanitizer API.
*/
static AtomsTable* sBaselineElementAllowlist;
/**
* The default configuration's attribute allow list used by the Sanitizer API.
*/
static AtomsTable* sDefaultConfigurationAttributeAllowlist;
/**
* The default configuration's element allow list used by the Sanitizer API.
*/
static AtomsTable* sDefaultConfigurationElementAllowlist;
/**
* Reusable null principal for URL checks.
*/
static nsIPrincipal* sNullPrincipal;
// === Variables used to implement HTML Sanitizer API. ==
// This nsTreeSanitizer instance should behave like the Sanitizer API.
bool mIsForSanitizerAPI = false;
bool mAllowCustomElements = false;
bool mAllowUnknownMarkup = false;
// An allow-list of elements to keep.
mozilla::UniquePtr<ElementNameSet> mAllowElements;
// A deny-list of elements to block. (aka flatten)
mozilla::UniquePtr<ElementNameSet> mBlockElements;
// A deny-list of elements to drop. (aka prune)
mozilla::UniquePtr<ElementNameSet> mDropElements;
// An allow-list of attributes to keep.
mozilla::UniquePtr<ElementToAttributeSetTable> mAllowedAttributes;
// A deny-list of attributes to drop.
mozilla::UniquePtr<ElementToAttributeSetTable> mDroppedAttributes;
};
#endif // nsTreeSanitizer_h_