Bug 1561653 - Drop URIs from remote types we use in telemetry. r=nika

With Fission enabled, remote types can have the form
webIsolated=<URI>. This is bad, because we store them in telemetry in
some places. This patch adds and uses a method that sanitizes remote
types.

Differential Revision: https://phabricator.services.mozilla.com/D36068

--HG--
extra : moz-landing-system : lando

dom/ipc/ContentChild.cpp

@@ -1752,8 +1752,10 @@ mozilla::ipc::IPCResult ContentChild::RecvSetProcessSandbox(
       CrashReporter::Annotation::ContentSandboxCapabilities,
       static_cast<int>(SandboxInfo::Get().AsInteger()));
 #  endif /* XP_LINUX && !OS_ANDROID */
+  // Use the prefix to avoid URIs from Fission isolated processes.
+  auto remoteTypePrefix = RemoteTypePrefix(GetRemoteType());
   CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::RemoteType,
-                                     NS_ConvertUTF16toUTF8(GetRemoteType()));
+                                     NS_ConvertUTF16toUTF8(remoteTypePrefix));
 #endif /* MOZ_SANDBOX */
 
   return IPC_OK();
@@ -2772,6 +2774,8 @@ mozilla::ipc::IPCResult ContentChild::RecvRemoteType(
   return IPC_OK();
 }
 
+// Call RemoteTypePrefix() on the result to remove URIs if you want to use this
+// for telemetry.
 const nsAString& ContentChild::GetRemoteType() const { return mRemoteType; }
 
 mozilla::ipc::IPCResult ContentChild::RecvInitServiceWorkers(

dom/ipc/ContentChild.h

@@ -415,6 +415,8 @@ class ContentChild final : public PContentChild,
 
   mozilla::ipc::IPCResult RecvRemoteType(const nsString& aRemoteType);
 
+  // Call RemoteTypePrefix() on the result to remove URIs if you want to use
+  // this for telemetry.
   const nsAString& GetRemoteType() const;
 
   mozilla::ipc::IPCResult RecvInitServiceWorkers(

dom/ipc/ContentParent.cpp

@@ -702,17 +702,23 @@ uint32_t ContentParent::GetPoolSize(const nsAString& aContentProcessType) {
   return *sBrowserContentParents->LookupOrAdd(aContentProcessType);
 }
 
-/*static*/
-uint32_t ContentParent::GetMaxProcessCount(
+const nsDependentSubstring RemoteTypePrefix(
     const nsAString& aContentProcessType) {
   // The suffix after a `=` in a remoteType is dynamic, and used to control the
-  // process pool to use. Max process count is based only on the prefix.
+  // process pool to use.
   int32_t equalIdx = aContentProcessType.FindChar(L'=');
   if (equalIdx == kNotFound) {
     equalIdx = aContentProcessType.Length();
   }
+  return StringHead(aContentProcessType, equalIdx);
+}
+
+/*static*/
+uint32_t ContentParent::GetMaxProcessCount(
+    const nsAString& aContentProcessType) {
+  // Max process count is based only on the prefix.
   const nsDependentSubstring processTypePrefix =
-      StringHead(aContentProcessType, equalIdx);
+    RemoteTypePrefix(aContentProcessType);
 
   // Check for the default remote type of "web", as it uses different prefs.
   if (processTypePrefix.EqualsLiteral("web")) {

dom/ipc/ContentParent.h

@@ -1355,6 +1355,8 @@ class ContentParent final : public PContentParent,
 
 NS_DEFINE_STATIC_IID_ACCESSOR(ContentParent, NS_CONTENTPARENT_IID)
 
+const nsDependentSubstring RemoteTypePrefix(
+    const nsAString& aContentProcessType);
 }  // namespace dom
 }  // namespace mozilla
 

toolkit/components/backgroundhangmonitor/HangDetails.cpp

@@ -3,6 +3,7 @@
 #include "nsPrintfCString.h"
 #include "mozilla/gfx/GPUParent.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/ContentParent.h"  // For RemoteTypePrefix
 #include "mozilla/Unused.h"
 #include "mozilla/GfxMessageUtils.h"  // For ParamTraits<GeckoProcessType>
 
@@ -255,7 +256,10 @@ void nsHangDetails::Submit() {
           case GeckoProcessType_Content: {
             auto cc = dom::ContentChild::GetSingleton();
             if (cc) {
-              hangDetails->mDetails.remoteType().Assign(cc->GetRemoteType());
+              // Use the prefix so we don't get URIs from Fission isolated
+              // processes.
+              hangDetails->mDetails.remoteType().Assign(
+                  dom::RemoteTypePrefix(cc->GetRemoteType()));
               Unused << cc->SendBHRThreadHang(hangDetails->mDetails);
             }
             break;

xpcom/system/nsIXULRuntime.idl

@@ -98,7 +98,9 @@ interface nsIXULRuntime : nsISupports
 
   /**
    * The type of remote content process we're running in.
-   * null if we're in the parent/chrome process.
+   * null if we're in the parent/chrome process. This can contain
+   * a URI if Fission is enabled, so don't use it for any kind of
+   * telemetry.
    */
   readonly attribute AString remoteType;