commit 292f7184a7e6bca2a628b5ca2bdfa005ec1f97db Author: Matthew Finkel sysrqb@torproject.org Date: Mon May 17 18:09:09 2021 +0000

Bug 40432: Prevent probing installed applications --- .../exthandler/nsExternalHelperAppService.cpp | 30 ++++++++++++++++++---- 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/uriloader/exthandler/nsExternalHelperAppService.cpp b/uriloader/exthandler/nsExternalHelperAppService.cpp index 2bc43fbc86b5..c218aa4f1447 100644 --- a/uriloader/exthandler/nsExternalHelperAppService.cpp +++ b/uriloader/exthandler/nsExternalHelperAppService.cpp @@ -1068,8 +1068,33 @@ nsresult nsExternalHelperAppService::GetFileTokenForPath( ////////////////////////////////////////////////////////////////////////////////////////////////////// // begin external protocol service default implementation... ////////////////////////////////////////////////////////////////////////////////////////////////////// + +static const char kExternalProtocolPrefPrefix[] = + "network.protocol-handler.external."; +static const char kExternalProtocolDefaultPref[] = + "network.protocol-handler.external-default"; + NS_IMETHODIMP nsExternalHelperAppService::ExternalProtocolHandlerExists( const char* aProtocolScheme, bool* aHandlerExists) { + + // Replicate the same check performed in LoadURI. + // Deny load if the prefs say to do so + nsAutoCString externalPref(kExternalProtocolPrefPrefix); + externalPref += aProtocolScheme; + bool allowLoad = false; + *aHandlerExists = false; + if (NS_FAILED(Preferences::GetBool(externalPref.get(), &allowLoad))) { + // no scheme-specific value, check the default + if (NS_FAILED( + Preferences::GetBool(kExternalProtocolDefaultPref, &allowLoad))) { + return NS_OK; // missing default pref + } + } + + if (!allowLoad) { + return NS_OK; // explicitly denied + } + nsCOMPtr<nsIHandlerInfo> handlerInfo; nsresult rv = GetProtocolHandlerInfo(nsDependentCString(aProtocolScheme), getter_AddRefs(handlerInfo)); @@ -1112,11 +1137,6 @@ NS_IMETHODIMP nsExternalHelperAppService::IsExposedProtocol( return NS_OK; }

-static const char kExternalProtocolPrefPrefix[] = - "network.protocol-handler.external."; -static const char kExternalProtocolDefaultPref[] = - "network.protocol-handler.external-default"; - NS_IMETHODIMP nsExternalHelperAppService::LoadURI(nsIURI* aURI, nsIPrincipal* aTriggeringPrincipal,