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-rw-r--r--ipc/glue/ForkServer.cpp298
1 files changed, 298 insertions, 0 deletions
diff --git a/ipc/glue/ForkServer.cpp b/ipc/glue/ForkServer.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=4 et sw=4 tw=80: */
+/* 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/ipc/ForkServer.h"
+#include "mozilla/Logging.h"
+#include "chrome/common/chrome_switches.h"
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/ipc/ProtocolMessageUtils.h"
+#include "mozilla/ipc/FileDescriptor.h"
+#include "mozilla/ipc/IPDLParamTraits.h"
+#include "ipc/IPCMessageUtilsSpecializations.h"
+#include "nsTraceRefcnt.h"
+
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+# include "mozilla/SandboxLaunch.h"
+#endif
+
+#include <algorithm>
+
+namespace mozilla {
+namespace ipc {
+
+LazyLogModule gForkServiceLog("ForkService");
+
+ForkServer::ForkServer() {}
+
+/**
+ * Prepare an environment for running a fork server.
+ */
+void ForkServer::InitProcess(int* aArgc, char*** aArgv) {
+ base::InitForkServerProcess();
+
+ mTcver = MakeUnique<MiniTransceiver>(kClientPipeFd,
+ DataBufferClear::AfterReceiving);
+}
+
+/**
+ * Start providing the service at the IPC channel.
+ */
+bool ForkServer::HandleMessages() {
+ while (true) {
+ UniquePtr<IPC::Message> msg;
+ if (!mTcver->Recv(msg)) {
+ break;
+ }
+
+ OnMessageReceived(std::move(msg));
+
+ if (mAppProcBuilder) {
+ // New process - child
+ return false;
+ }
+ }
+ // Stop the server
+ return true;
+}
+
+inline void CleanCString(nsCString& str) {
+ char* data;
+ int sz = str.GetMutableData(&data);
+
+ memset(data, ' ', sz);
+}
+
+inline void CleanString(std::string& str) {
+ const char deadbeef[] =
+ "\xde\xad\xbe\xef\xde\xad\xbe\xef\xde\xad\xbe\xef\xde\xad\xbe\xef"
+ "\xde\xad\xbe\xef\xde\xad\xbe\xef\xde\xad\xbe\xef\xde\xad\xbe\xef";
+ int pos = 0;
+ size_t sz = str.size();
+ while (sz > 0) {
+ int toclean = std::min(sz, sizeof(deadbeef) - 1);
+ str.replace(pos, toclean, deadbeef);
+ sz -= toclean;
+ pos += toclean;
+ }
+}
+
+inline void PrepareArguments(std::vector<std::string>& aArgv,
+ nsTArray<nsCString>& aArgvArray) {
+ for (auto& elt : aArgvArray) {
+ aArgv.push_back(elt.get());
+ CleanCString(elt);
+ }
+}
+
+// Prepare aOptions->env_map
+inline void PrepareEnv(base::LaunchOptions* aOptions,
+ nsTArray<EnvVar>& aEnvMap) {
+ for (auto& elt : aEnvMap) {
+ nsCString& var = Get<0>(elt);
+ nsCString& val = Get<1>(elt);
+ aOptions->env_map[var.get()] = val.get();
+ CleanCString(var);
+ CleanCString(val);
+ }
+}
+
+// Prepare aOptions->fds_to_remap
+inline void PrepareFdsRemap(base::LaunchOptions* aOptions,
+ nsTArray<FdMapping>& aFdsRemap) {
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose, ("fds mapping:"));
+ for (auto& elt : aFdsRemap) {
+ // FDs are duplicated here.
+ int fd = Get<0>(elt).ClonePlatformHandle().release();
+ std::pair<int, int> fdmap(fd, Get<1>(elt));
+ aOptions->fds_to_remap.push_back(fdmap);
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose,
+ ("\t%d => %d", fdmap.first, fdmap.second));
+ }
+}
+
+template <class P>
+static void ReadParamInfallible(IPC::MessageReader* aReader, P* aResult,
+ const char* aCrashMessage) {
+ if (!IPC::ReadParam(aReader, aResult)) {
+ MOZ_CRASH_UNSAFE(aCrashMessage);
+ }
+}
+
+/**
+ * Parse a Message to get a list of arguments and fill a LaunchOptions.
+ */
+inline bool ParseForkNewSubprocess(IPC::Message& aMsg,
+ std::vector<std::string>& aArgv,
+ base::LaunchOptions* aOptions) {
+ if (aMsg.type() != Msg_ForkNewSubprocess__ID) {
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose,
+ ("unknown message type %d\n", aMsg.type()));
+ return false;
+ }
+
+ IPC::MessageReader reader(aMsg);
+ nsTArray<nsCString> argv_array;
+ nsTArray<EnvVar> env_map;
+ nsTArray<FdMapping> fds_remap;
+
+ ReadParamInfallible(&reader, &argv_array,
+ "Error deserializing 'nsCString[]'");
+ ReadParamInfallible(&reader, &env_map, "Error deserializing 'EnvVar[]'");
+ ReadParamInfallible(&reader, &fds_remap, "Error deserializing 'FdMapping[]'");
+ reader.EndRead();
+
+ PrepareArguments(aArgv, argv_array);
+ PrepareEnv(aOptions, env_map);
+ PrepareFdsRemap(aOptions, fds_remap);
+
+ return true;
+}
+
+inline void SanitizeBuffers(IPC::Message& aMsg, std::vector<std::string>& aArgv,
+ base::LaunchOptions& aOptions) {
+ // Clean all buffers in the message to make sure content processes
+ // not peeking others.
+ auto& blist = aMsg.Buffers();
+ for (auto itr = blist.Iter(); !itr.Done();
+ itr.Advance(blist, itr.RemainingInSegment())) {
+ memset(itr.Data(), 0, itr.RemainingInSegment());
+ }
+
+ // clean all data string made from the message.
+ for (auto& var : aOptions.env_map) {
+ // Do it anyway since it is not going to be used anymore.
+ CleanString(*const_cast<std::string*>(&var.first));
+ CleanString(var.second);
+ }
+ for (auto& arg : aArgv) {
+ CleanString(arg);
+ }
+}
+
+/**
+ * Extract parameters from the |Message| to create a
+ * |base::AppProcessBuilder| as |mAppProcBuilder|.
+ *
+ * It will return in both the fork server process and the new content
+ * process. |mAppProcBuilder| is null for the fork server.
+ */
+void ForkServer::OnMessageReceived(UniquePtr<IPC::Message> message) {
+ std::vector<std::string> argv;
+ base::LaunchOptions options;
+ if (!ParseForkNewSubprocess(*message, argv, &options)) {
+ return;
+ }
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+ mozilla::SandboxLaunchForkServerPrepare(argv, options);
+#endif
+
+ base::ProcessHandle child_pid = -1;
+ mAppProcBuilder = MakeUnique<base::AppProcessBuilder>();
+ if (!mAppProcBuilder->ForkProcess(argv, options, &child_pid)) {
+ MOZ_CRASH("fail to fork");
+ }
+ MOZ_ASSERT(child_pid >= 0);
+
+ if (child_pid == 0) {
+ // Content process
+ return;
+ }
+
+ // Fork server process
+
+ mAppProcBuilder = nullptr;
+
+ IPC::Message reply(MSG_ROUTING_CONTROL, Reply_ForkNewSubprocess__ID);
+ IPC::MessageWriter writer(reply);
+ WriteIPDLParam(&writer, nullptr, child_pid);
+ mTcver->SendInfallible(reply, "failed to send a reply message");
+
+ // Without this, the content processes that is forked later are
+ // able to read the content of buffers even the buffers have been
+ // released.
+ SanitizeBuffers(*message, argv, options);
+}
+
+/**
+ * Setup and run a fork server at the main thread.
+ *
+ * This function returns for two reasons:
+ * - the fork server is stopped normally, or
+ * - a new process is forked from the fork server and this function
+ * returned in the child, the new process.
+ *
+ * For the later case, aArgc and aArgv are modified to pass the
+ * arguments from the chrome process.
+ */
+bool ForkServer::RunForkServer(int* aArgc, char*** aArgv) {
+#ifdef DEBUG
+ if (getenv("MOZ_FORKSERVER_WAIT_GDB")) {
+ printf(
+ "Waiting for 30 seconds."
+ " Attach the fork server with gdb %s %d\n",
+ (*aArgv)[0], base::GetCurrentProcId());
+ sleep(30);
+ }
+ bool sleep_newproc = !!getenv("MOZ_FORKSERVER_WAIT_GDB_NEWPROC");
+#endif
+
+ // Do this before NS_LogInit() to avoid log files taking lower
+ // FDs.
+ ForkServer forkserver;
+ forkserver.InitProcess(aArgc, aArgv);
+
+ XRE_SetProcessType("forkserver");
+ NS_LogInit();
+ mozilla::LogModule::Init(0, nullptr);
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose, ("Start a fork server"));
+ {
+ DebugOnly<base::ProcessHandle> forkserver_pid = base::GetCurrentProcId();
+ if (forkserver.HandleMessages()) {
+ // In the fork server process
+ // The server has stopped.
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose,
+ ("Terminate the fork server"));
+ NS_LogTerm();
+ return true;
+ }
+ // Now, we are running in a content process just forked from
+ // the fork server process.
+ MOZ_ASSERT(base::GetCurrentProcId() != forkserver_pid);
+ MOZ_LOG(gForkServiceLog, LogLevel::Verbose, ("Fork a new content process"));
+ }
+#ifdef DEBUG
+ if (sleep_newproc) {
+ printf(
+ "Waiting for 30 seconds."
+ " Attach the new process with gdb %s %d\n",
+ (*aArgv)[0], base::GetCurrentProcId());
+ sleep(30);
+ }
+#endif
+ NS_LogTerm();
+
+ MOZ_ASSERT(forkserver.mAppProcBuilder);
+ // |messageloop| has been destroyed. So, we can intialized the
+ // process safely. Message loops may allocates some file
+ // descriptors. If it is destroyed later, it may mess up this
+ // content process by closing wrong file descriptors.
+ forkserver.mAppProcBuilder->InitAppProcess(aArgc, aArgv);
+ forkserver.mAppProcBuilder.reset();
+
+ MOZ_ASSERT("tab"_ns == (*aArgv)[*aArgc - 1], "Only |tab| is allowed!");
+
+ // Open log files again with right names and the new PID.
+ nsTraceRefcnt::ResetLogFiles((*aArgv)[*aArgc - 1]);
+
+ return false;
+}
+
+} // namespace ipc
+} // namespace mozilla
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