gecko/js/xpconnect/wrappers/AccessCheck.cpp
Bobby Holley 4473d2369c Bug 788914 - Kill the XOW flag. r=mrbkap
There are really two questions to be asked: is the caller chrome, and does the
caller subsume the callee. We have other, more precise ways of asking both of
these questions.
2012-09-11 01:05:10 -07:00

551 lines
16 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=4 sw=4 et tw=99 ft=cpp:
*
* 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/. */
#include "mozilla/Util.h"
#include "AccessCheck.h"
#include "nsJSPrincipals.h"
#include "nsIDOMWindow.h"
#include "nsIDOMWindowCollection.h"
#include "nsContentUtils.h"
#include "nsJSUtils.h"
#include "XPCWrapper.h"
#include "XrayWrapper.h"
#include "FilteringWrapper.h"
#include "jsfriendapi.h"
using namespace mozilla;
using namespace js;
namespace xpc {
nsIPrincipal *
GetCompartmentPrincipal(JSCompartment *compartment)
{
return nsJSPrincipals::get(JS_GetCompartmentPrincipals(compartment));
}
// Does the principal of compartment a subsume the principal of compartment b?
bool
AccessCheck::subsumes(JSCompartment *a, JSCompartment *b)
{
nsIPrincipal *aprin = GetCompartmentPrincipal(a);
nsIPrincipal *bprin = GetCompartmentPrincipal(b);
// If either a or b doesn't have principals, we don't have enough
// information to tell. Seeing as how this is Gecko, we are default-unsafe
// in this case.
if (!aprin || !bprin)
return true;
bool subsumes;
nsresult rv = aprin->Subsumes(bprin, &subsumes);
NS_ENSURE_SUCCESS(rv, false);
return subsumes;
}
// Does the compartment of the wrapper subsumes the compartment of the wrappee?
bool
AccessCheck::wrapperSubsumes(JSObject *wrapper)
{
MOZ_ASSERT(js::IsWrapper(wrapper));
JSObject *wrapped = js::UnwrapObject(wrapper);
return AccessCheck::subsumes(js::GetObjectCompartment(wrapper),
js::GetObjectCompartment(wrapped));
}
bool
AccessCheck::isLocationObjectSameOrigin(JSContext *cx, JSObject *wrapper)
{
// The caller must ensure that the given wrapper wraps a Location object.
MOZ_ASSERT(WrapperFactory::IsLocationObject(js::UnwrapObject(wrapper)));
// Location objects are parented to the outer window for which they
// were created. This gives us an easy way to determine whether our
// object is same origin with the current inner window:
// Grab the outer window...
JSObject *obj = js::GetObjectParent(js::UnwrapObject(wrapper));
if (!js::GetObjectClass(obj)->ext.innerObject) {
// ...which might be wrapped in a security wrapper.
obj = js::UnwrapObject(obj);
JS_ASSERT(js::GetObjectClass(obj)->ext.innerObject);
}
// Now innerize it to find the *current* inner window for our outer.
obj = JS_ObjectToInnerObject(cx, obj);
// Which lets us compare the current compartment against the old one.
return obj && subsumes(js::GetObjectCompartment(wrapper),
js::GetObjectCompartment(obj));
}
bool
AccessCheck::isChrome(JSCompartment *compartment)
{
nsIScriptSecurityManager *ssm = XPCWrapper::GetSecurityManager();
if (!ssm) {
return false;
}
bool privileged;
nsIPrincipal *principal = GetCompartmentPrincipal(compartment);
return NS_SUCCEEDED(ssm->IsSystemPrincipal(principal, &privileged)) && privileged;
}
bool
AccessCheck::isChrome(JSObject *obj)
{
return isChrome(js::GetObjectCompartment(obj));
}
bool
AccessCheck::callerIsChrome()
{
nsIScriptSecurityManager *ssm = XPCWrapper::GetSecurityManager();
if (!ssm)
return false;
bool subjectIsSystem;
nsresult rv = ssm->SubjectPrincipalIsSystem(&subjectIsSystem);
return NS_SUCCEEDED(rv) && subjectIsSystem;
}
nsIPrincipal *
AccessCheck::getPrincipal(JSCompartment *compartment)
{
return GetCompartmentPrincipal(compartment);
}
#define NAME(ch, str, cases) \
case ch: if (!strcmp(name, str)) switch (propChars[0]) { cases }; break;
#define PROP(ch, actions) case ch: { actions }; break;
#define RW(str) if (JS_FlatStringEqualsAscii(prop, str)) return true;
#define R(str) if (!set && JS_FlatStringEqualsAscii(prop, str)) return true;
#define W(str) if (set && JS_FlatStringEqualsAscii(prop, str)) return true;
// Hardcoded policy for cross origin property access. This was culled from the
// preferences file (all.js). We don't want users to overwrite highly sensitive
// security policies.
static bool
IsPermitted(const char *name, JSFlatString *prop, bool set)
{
size_t propLength;
const jschar *propChars =
JS_GetInternedStringCharsAndLength(JS_FORGET_STRING_FLATNESS(prop), &propLength);
if (!propLength)
return false;
switch (name[0]) {
NAME('H', "History",
PROP('b', R("back"))
PROP('f', R("forward"))
PROP('g', R("go")))
NAME('L', "Location",
PROP('h', W("hash") W("href"))
PROP('r', R("replace")))
NAME('W', "Window",
PROP('b', R("blur"))
PROP('c', R("close") R("closed"))
PROP('f', R("focus") R("frames"))
PROP('h', R("history"))
PROP('l', RW("location") R("length"))
PROP('o', R("opener"))
PROP('p', R("parent") R("postMessage"))
PROP('s', R("self"))
PROP('t', R("top"))
PROP('w', R("window")))
}
return false;
}
#undef NAME
#undef RW
#undef R
#undef W
static bool
IsFrameId(JSContext *cx, JSObject *obj, jsid id)
{
XPCWrappedNative *wn = XPCWrappedNative::GetWrappedNativeOfJSObject(cx, obj);
if (!wn) {
return false;
}
nsCOMPtr<nsIDOMWindow> domwin(do_QueryWrappedNative(wn));
if (!domwin) {
return false;
}
nsCOMPtr<nsIDOMWindowCollection> col;
domwin->GetFrames(getter_AddRefs(col));
if (!col) {
return false;
}
if (JSID_IS_INT(id)) {
col->Item(JSID_TO_INT(id), getter_AddRefs(domwin));
} else if (JSID_IS_STRING(id)) {
nsAutoString str(JS_GetInternedStringChars(JSID_TO_STRING(id)));
col->NamedItem(str, getter_AddRefs(domwin));
} else {
return false;
}
return domwin != nullptr;
}
static bool
IsWindow(const char *name)
{
return name[0] == 'W' && !strcmp(name, "Window");
}
bool
AccessCheck::isCrossOriginAccessPermitted(JSContext *cx, JSObject *wrapper, jsid id,
Wrapper::Action act)
{
if (!XPCWrapper::GetSecurityManager())
return true;
if (act == Wrapper::CALL)
return true;
JSObject *obj = Wrapper::wrappedObject(wrapper);
// PUNCTURE Is always denied for cross-origin access.
if (act == Wrapper::PUNCTURE) {
return false;
}
const char *name;
js::Class *clasp = js::GetObjectClass(obj);
NS_ASSERTION(Jsvalify(clasp) != &XrayUtils::HolderClass, "shouldn't have a holder here");
if (clasp->ext.innerObject)
name = "Window";
else
name = clasp->name;
if (JSID_IS_STRING(id)) {
if (IsPermitted(name, JSID_TO_FLAT_STRING(id), act == Wrapper::SET))
return true;
}
if (IsWindow(name) && IsFrameId(cx, obj, id))
return true;
return (act == Wrapper::SET)
? nsContentUtils::IsCallerTrustedForWrite()
: nsContentUtils::IsCallerTrustedForRead();
}
bool
AccessCheck::isSystemOnlyAccessPermitted(JSContext *cx)
{
nsIScriptSecurityManager *ssm = XPCWrapper::GetSecurityManager();
if (!ssm) {
return true;
}
JSStackFrame *fp;
nsIPrincipal *principal = ssm->GetCxSubjectPrincipalAndFrame(cx, &fp);
if (!principal) {
return false;
}
JSScript *script = nullptr;
if (fp) {
script = JS_GetFrameScript(cx, fp);
} else {
if (!JS_DescribeScriptedCaller(cx, &script, nullptr)) {
// No code at all is running. So we must be arriving here as the result
// of C++ code asking us to do something. Allow access.
return true;
}
}
bool privileged;
if (NS_SUCCEEDED(ssm->IsSystemPrincipal(principal, &privileged)) &&
privileged) {
return true;
}
// Allow any code loaded from chrome://global/ to touch us, even if it was
// cloned into a less privileged context.
static const char prefix[] = "chrome://global/";
const char *filename;
if (script &&
(filename = JS_GetScriptFilename(cx, script)) &&
!strncmp(filename, prefix, ArrayLength(prefix) - 1)) {
return true;
}
return false;
}
bool
AccessCheck::needsSystemOnlyWrapper(JSObject *obj)
{
if (!IS_WN_WRAPPER(obj))
return false;
XPCWrappedNative *wn = static_cast<XPCWrappedNative *>(js::GetObjectPrivate(obj));
return wn->NeedsSOW();
}
bool
AccessCheck::isScriptAccessOnly(JSContext *cx, JSObject *wrapper)
{
JS_ASSERT(js::IsWrapper(wrapper));
unsigned flags;
JSObject *obj = js::UnwrapObject(wrapper, true, &flags);
// If the wrapper indicates script-only access, we are done.
if (flags & WrapperFactory::SCRIPT_ACCESS_ONLY_FLAG) {
if (flags & WrapperFactory::SOW_FLAG)
return !isSystemOnlyAccessPermitted(cx);
return true;
}
// In addition, chrome objects can explicitly opt-in by setting .scriptOnly to true.
if (js::GetProxyHandler(wrapper) ==
&FilteringWrapper<CrossCompartmentSecurityWrapper,
CrossOriginAccessiblePropertiesOnly>::singleton) {
jsid scriptOnlyId = GetRTIdByIndex(cx, XPCJSRuntime::IDX_SCRIPTONLY);
jsval scriptOnly;
if (JS_LookupPropertyById(cx, obj, scriptOnlyId, &scriptOnly) &&
scriptOnly == JSVAL_TRUE)
return true; // script-only
}
// Allow non-script access to same-origin location objects and any other
// objects.
return WrapperFactory::IsLocationObject(obj) && !isLocationObjectSameOrigin(cx, wrapper);
}
void
AccessCheck::deny(JSContext *cx, jsid id)
{
if (id == JSID_VOID) {
JS_ReportError(cx, "Permission denied to access object");
} else {
jsval idval;
if (!JS_IdToValue(cx, id, &idval))
return;
JSString *str = JS_ValueToString(cx, idval);
if (!str)
return;
const jschar *chars = JS_GetStringCharsZ(cx, str);
if (chars)
JS_ReportError(cx, "Permission denied to access property '%hs'", chars);
}
}
enum Access { READ = (1<<0), WRITE = (1<<1), NO_ACCESS = 0 };
static bool
Deny(JSContext *cx, jsid id, Wrapper::Action act)
{
// Refuse to perform the action and just return the default value.
if (act == Wrapper::GET)
return true;
// If its a set, deny it and throw an exception.
AccessCheck::deny(cx, id);
return false;
}
static bool
IsInSandbox(JSContext *cx, JSObject *obj)
{
JSAutoCompartment ac(cx, obj);
JSObject *global = JS_GetGlobalForObject(cx, obj);
return !strcmp(js::GetObjectJSClass(global)->name, "Sandbox");
}
bool
ExposedPropertiesOnly::check(JSContext *cx, JSObject *wrapper, jsid id, Wrapper::Action act,
Permission &perm)
{
JSObject *wrappedObject = Wrapper::wrappedObject(wrapper);
if (act == Wrapper::CALL) {
perm = PermitObjectAccess;
return true;
}
perm = DenyAccess;
if (act == Wrapper::PUNCTURE)
return Deny(cx, id, act);
jsid exposedPropsId = GetRTIdByIndex(cx, XPCJSRuntime::IDX_EXPOSEDPROPS);
// We need to enter the wrappee's compartment to look at __exposedProps__,
// but we want to be in the wrapper's compartment if we call Deny().
//
// Unfortunately, |cx| can be in either compartment when we call ::check. :-(
JSAutoCompartment ac(cx, wrappedObject);
JSBool found = false;
if (!JS_HasPropertyById(cx, wrappedObject, exposedPropsId, &found))
return false;
// Always permit access to "length" and indexed properties of arrays.
if ((JS_IsArrayObject(cx, wrappedObject) ||
JS_IsTypedArrayObject(wrappedObject, cx)) &&
((JSID_IS_INT(id) && JSID_TO_INT(id) >= 0) ||
(JSID_IS_STRING(id) && JS_FlatStringEqualsAscii(JSID_TO_FLAT_STRING(id), "length")))) {
perm = PermitPropertyAccess;
return true; // Allow
}
// If no __exposedProps__ existed, deny access.
if (!found) {
// Everything below here needs to be done in the wrapper's compartment.
JSAutoCompartment wrapperAC(cx, wrapper);
// Make a temporary exception for objects in a chrome sandbox to help
// out jetpack. See bug 784233.
if (!JS_ObjectIsFunction(cx, wrappedObject) &&
IsInSandbox(cx, wrappedObject))
{
// This little loop hole will go away soon! See bug 553102.
nsCOMPtr<nsPIDOMWindow> win =
do_QueryInterface(nsJSUtils::GetStaticScriptGlobal(cx, wrapper));
if (win) {
nsCOMPtr<nsIDocument> doc =
do_QueryInterface(win->GetExtantDocument());
if (doc) {
doc->WarnOnceAbout(nsIDocument::eNoExposedProps,
/* asError = */ true);
}
}
perm = PermitPropertyAccess;
return true;
}
return Deny(cx, id, act);
}
if (id == JSID_VOID) {
// This will force the caller to call us back for individual property accesses.
perm = PermitPropertyAccess;
return true;
}
JS::Value exposedProps;
if (!JS_LookupPropertyById(cx, wrappedObject, exposedPropsId, &exposedProps))
return false;
if (exposedProps.isNullOrUndefined()) {
JSAutoCompartment wrapperAC(cx, wrapper);
return Deny(cx, id, act);
}
if (!exposedProps.isObject()) {
JS_ReportError(cx, "__exposedProps__ must be undefined, null, or an Object");
return false;
}
JSObject *hallpass = &exposedProps.toObject();
Access access = NO_ACCESS;
JSPropertyDescriptor desc;
memset(&desc, 0, sizeof(desc));
if (!JS_GetPropertyDescriptorById(cx, hallpass, id, JSRESOLVE_QUALIFIED, &desc)) {
return false; // Error
}
if (desc.obj == NULL || !(desc.attrs & JSPROP_ENUMERATE)) {
JSAutoCompartment wrapperAC(cx, wrapper);
return Deny(cx, id, act);
}
if (!JSVAL_IS_STRING(desc.value)) {
JS_ReportError(cx, "property must be a string");
return false;
}
JSString *str = JSVAL_TO_STRING(desc.value);
size_t length;
const jschar *chars = JS_GetStringCharsAndLength(cx, str, &length);
if (!chars)
return false;
for (size_t i = 0; i < length; ++i) {
switch (chars[i]) {
case 'r':
if (access & READ) {
JS_ReportError(cx, "duplicate 'readable' property flag");
return false;
}
access = Access(access | READ);
break;
case 'w':
if (access & WRITE) {
JS_ReportError(cx, "duplicate 'writable' property flag");
return false;
}
access = Access(access | WRITE);
break;
default:
JS_ReportError(cx, "properties can only be readable or read and writable");
return false;
}
}
if (access == NO_ACCESS) {
JS_ReportError(cx, "specified properties must have a permission bit set");
return false;
}
if ((act == Wrapper::SET && !(access & WRITE)) ||
(act != Wrapper::SET && !(access & READ))) {
JSAutoCompartment wrapperAC(cx, wrapper);
return Deny(cx, id, act);
}
perm = PermitPropertyAccess;
return true; // Allow
}
bool
ComponentsObjectPolicy::check(JSContext *cx, JSObject *wrapper, jsid id, Wrapper::Action act,
Permission &perm)
{
perm = DenyAccess;
JSAutoCompartment ac(cx, wrapper);
if (JSID_IS_STRING(id) && act == Wrapper::GET) {
JSFlatString *flatId = JSID_TO_FLAT_STRING(id);
if (JS_FlatStringEqualsAscii(flatId, "isSuccessCode") ||
JS_FlatStringEqualsAscii(flatId, "lookupMethod") ||
JS_FlatStringEqualsAscii(flatId, "interfaces") ||
JS_FlatStringEqualsAscii(flatId, "interfacesByID") ||
JS_FlatStringEqualsAscii(flatId, "results"))
{
perm = PermitPropertyAccess;
return true;
}
}
// We don't have any way to recompute same-compartment Components wrappers,
// so we need this dynamic check. This can go away when we expose Components
// as SpecialPowers.wrap(Components) during automation.
if (xpc::IsUniversalXPConnectEnabled(cx)) {
perm = PermitPropertyAccess;
return true;
}
return Deny(cx, id, act);
}
}