1 files changed, 348 insertions, 0 deletions
diff --git a/xpcom/build/PoisonIOInterposerMac.cpp b/xpcom/build/PoisonIOInterposerMac.cpp
new file mode 100644
index 0000000000..21eca58757
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposerMac.cpp
@@ -0,0 +1,348 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 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 "PoisonIOInterposer.h"
+// Disabled until bug 1658385 is fixed.
+#ifndef __aarch64__
+#  include "mach_override.h"
+#endif
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/ProcessedStack.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "nsPrintfCString.h"
+#include "mozilla/StackWalk.h"
+#include "nsTraceRefcnt.h"
+#include "prio.h"
+
+#include <algorithm>
+#include <vector>
+
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <aio.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#ifdef MOZ_REPLACE_MALLOC
+#  include "replace_malloc_bridge.h"
+#endif
+
+namespace {
+
+// Bit tracking if poisoned writes are enabled
+static bool sIsEnabled = false;
+
+// Check if writes are dirty before reporting IO
+static bool sOnlyReportDirtyWrites = false;
+
+// Routines for write validation
+bool IsValidWrite(int aFd, const void* aWbuf, size_t aCount);
+bool IsIPCWrite(int aFd, const struct stat& aBuf);
+
+/******************************** IO AutoTimer ********************************/
+
+/**
+ * RAII class for timing the duration of an I/O call and reporting the result
+ * to the mozilla::IOInterposeObserver API.
+ */
+class MacIOAutoObservation : public mozilla::IOInterposeObserver::Observation {
+ public:
+  MacIOAutoObservation(mozilla::IOInterposeObserver::Operation aOp, int aFd)
+      : mozilla::IOInterposeObserver::Observation(
+            aOp, sReference, sIsEnabled && !mozilla::IsDebugFile(aFd)),
+        mFd(aFd),
+        mHasQueriedFilename(false) {}
+
+  MacIOAutoObservation(mozilla::IOInterposeObserver::Operation aOp, int aFd,
+                       const void* aBuf, size_t aCount)
+      : mozilla::IOInterposeObserver::Observation(
+            aOp, sReference,
+            sIsEnabled && !mozilla::IsDebugFile(aFd) &&
+                IsValidWrite(aFd, aBuf, aCount)),
+        mFd(aFd),
+        mHasQueriedFilename(false) {}
+
+  // Custom implementation of
+  // mozilla::IOInterposeObserver::Observation::Filename
+  void Filename(nsAString& aFilename) override;
+
+  ~MacIOAutoObservation() { Report(); }
+
+ private:
+  int mFd;
+  bool mHasQueriedFilename;
+  nsString mFilename;
+  static const char* sReference;
+};
+
+const char* MacIOAutoObservation::sReference = "PoisonIOInterposer";
+
+// Get filename for this observation
+void MacIOAutoObservation::Filename(nsAString& aFilename) {
+  // If mHasQueriedFilename is true, then we already have it
+  if (mHasQueriedFilename) {
+    aFilename = mFilename;
+    return;
+  }
+
+  char filename[MAXPATHLEN];
+  if (fcntl(mFd, F_GETPATH, filename) != -1) {
+    CopyUTF8toUTF16(filename, mFilename);
+  } else {
+    mFilename.Truncate();
+  }
+  mHasQueriedFilename = true;
+
+  aFilename = mFilename;
+}
+
+/****************************** Write Validation ******************************/
+
+// We want to detect "actual" writes, not IPC. Some IPC mechanisms are
+// implemented with file descriptors, so filter them out.
+bool IsIPCWrite(int aFd, const struct stat& aBuf) {
+  if ((aBuf.st_mode & S_IFMT) == S_IFIFO) {
+    return true;
+  }
+
+  if ((aBuf.st_mode & S_IFMT) != S_IFSOCK) {
+    return false;
+  }
+
+  sockaddr_storage address;
+  socklen_t len = sizeof(address);
+  if (getsockname(aFd, (sockaddr*)&address, &len) != 0) {
+    return true;  // Ignore the aFd if we can't find what it is.
+  }
+
+  return address.ss_family == AF_UNIX;
+}
+
+// We want to report actual disk IO not things that don't move bits on the disk
+bool IsValidWrite(int aFd, const void* aWbuf, size_t aCount) {
+  // Ignore writes of zero bytes, Firefox does some during shutdown.
+  if (aCount == 0) {
+    return false;
+  }
+
+  {
+    struct stat buf;
+    int rv = fstat(aFd, &buf);
+    if (rv != 0) {
+      return true;
+    }
+
+    if (IsIPCWrite(aFd, buf)) {
+      return false;
+    }
+  }
+
+  // For writev we pass a nullptr aWbuf. We should only get here from
+  // dbm, and it uses write, so assert that we have aWbuf.
+  if (!aWbuf) {
+    return true;
+  }
+
+  // Break, here if we're allowed to report non-dirty writes
+  if (!sOnlyReportDirtyWrites) {
+    return true;
+  }
+
+  // As a really bad hack, accept writes that don't change the on disk
+  // content. This is needed because dbm doesn't keep track of dirty bits
+  // and can end up writing the same data to disk twice. Once when the
+  // user (nss) asks it to sync and once when closing the database.
+  auto wbuf2 = mozilla::MakeUniqueFallible<char[]>(aCount);
+  if (!wbuf2) {
+    return true;
+  }
+  off_t pos = lseek(aFd, 0, SEEK_CUR);
+  if (pos == -1) {
+    return true;
+  }
+  ssize_t r = read(aFd, wbuf2.get(), aCount);
+  if (r < 0 || (size_t)r != aCount) {
+    return true;
+  }
+  int cmp = memcmp(aWbuf, wbuf2.get(), aCount);
+  if (cmp != 0) {
+    return true;
+  }
+  off_t pos2 = lseek(aFd, pos, SEEK_SET);
+  if (pos2 != pos) {
+    return true;
+  }
+
+  // Otherwise this is not a valid write
+  return false;
+}
+
+/*************************** Function Interception  ***************************/
+
+/** Structure for declaration of function override */
+struct FuncData {
+  const char* Name;     // Name of the function for the ones we use dlsym
+  const void* Wrapper;  // The function that we will replace 'Function' with
+  void* Function;       // The function that will be replaced with 'Wrapper'
+  void* Buffer;         // Will point to the jump buffer that lets us call
+                        // 'Function' after it has been replaced.
+};
+
+// Wrap aio_write. We have not seen it before, so just assert/report it.
+typedef ssize_t (*aio_write_t)(struct aiocb* aAioCbp);
+ssize_t wrap_aio_write(struct aiocb* aAioCbp);
+FuncData aio_write_data = {0, (void*)wrap_aio_write, (void*)aio_write};
+ssize_t wrap_aio_write(struct aiocb* aAioCbp) {
+  MacIOAutoObservation timer(mozilla::IOInterposeObserver::OpWrite,
+                             aAioCbp->aio_fildes);
+
+  aio_write_t old_write = (aio_write_t)aio_write_data.Buffer;
+  return old_write(aAioCbp);
+}
+
+// Wrap pwrite-like functions.
+// We have not seen them before, so just assert/report it.
+typedef ssize_t (*pwrite_t)(int aFd, const void* buf, size_t aNumBytes,
+                            off_t aOffset);
+template <FuncData& foo>
+ssize_t wrap_pwrite_temp(int aFd, const void* aBuf, size_t aNumBytes,
+                         off_t aOffset) {
+  MacIOAutoObservation timer(mozilla::IOInterposeObserver::OpWrite, aFd);
+  pwrite_t old_write = (pwrite_t)foo.Buffer;
+  return old_write(aFd, aBuf, aNumBytes, aOffset);
+}
+
+// Define a FuncData for a pwrite-like functions.
+#define DEFINE_PWRITE_DATA(X, NAME) \
+  FuncData X##_data = {NAME, (void*)wrap_pwrite_temp<X##_data>};
+
+// This exists everywhere.
+DEFINE_PWRITE_DATA(pwrite, "pwrite")
+// These exist on 32 bit OS X
+DEFINE_PWRITE_DATA(pwrite_NOCANCEL_UNIX2003, "pwrite$NOCANCEL$UNIX2003");
+DEFINE_PWRITE_DATA(pwrite_UNIX2003, "pwrite$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_PWRITE_DATA(pwrite_NOCANCEL, "pwrite$NOCANCEL");
+
+typedef ssize_t (*writev_t)(int aFd, const struct iovec* aIov, int aIovCount);
+template <FuncData& foo>
+ssize_t wrap_writev_temp(int aFd, const struct iovec* aIov, int aIovCount) {
+  MacIOAutoObservation timer(mozilla::IOInterposeObserver::OpWrite, aFd,
+                             nullptr, aIovCount);
+  writev_t old_write = (writev_t)foo.Buffer;
+  return old_write(aFd, aIov, aIovCount);
+}
+
+// Define a FuncData for a writev-like functions.
+#define DEFINE_WRITEV_DATA(X, NAME) \
+  FuncData X##_data = {NAME, (void*)wrap_writev_temp<X##_data>};
+
+// This exists everywhere.
+DEFINE_WRITEV_DATA(writev, "writev");
+// These exist on 32 bit OS X
+DEFINE_WRITEV_DATA(writev_NOCANCEL_UNIX2003, "writev$NOCANCEL$UNIX2003");
+DEFINE_WRITEV_DATA(writev_UNIX2003, "writev$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_WRITEV_DATA(writev_NOCANCEL, "writev$NOCANCEL");
+
+typedef ssize_t (*write_t)(int aFd, const void* aBuf, size_t aCount);
+template <FuncData& foo>
+ssize_t wrap_write_temp(int aFd, const void* aBuf, size_t aCount) {
+  MacIOAutoObservation timer(mozilla::IOInterposeObserver::OpWrite, aFd, aBuf,
+                             aCount);
+  write_t old_write = (write_t)foo.Buffer;
+  return old_write(aFd, aBuf, aCount);
+}
+
+// Define a FuncData for a write-like functions.
+#define DEFINE_WRITE_DATA(X, NAME) \
+  FuncData X##_data = {NAME, (void*)wrap_write_temp<X##_data>};
+
+// This exists everywhere.
+DEFINE_WRITE_DATA(write, "write");
+// These exist on 32 bit OS X
+DEFINE_WRITE_DATA(write_NOCANCEL_UNIX2003, "write$NOCANCEL$UNIX2003");
+DEFINE_WRITE_DATA(write_UNIX2003, "write$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_WRITE_DATA(write_NOCANCEL, "write$NOCANCEL");
+
+FuncData* Functions[] = {&aio_write_data,
+
+                         &pwrite_data,          &pwrite_NOCANCEL_UNIX2003_data,
+                         &pwrite_UNIX2003_data, &pwrite_NOCANCEL_data,
+
+                         &write_data,           &write_NOCANCEL_UNIX2003_data,
+                         &write_UNIX2003_data,  &write_NOCANCEL_data,
+
+                         &writev_data,          &writev_NOCANCEL_UNIX2003_data,
+                         &writev_UNIX2003_data, &writev_NOCANCEL_data};
+
+const int NumFunctions = mozilla::ArrayLength(Functions);
+
+}  // namespace
+
+/******************************** IO Poisoning ********************************/
+
+namespace mozilla {
+
+void InitPoisonIOInterposer() {
+  // Enable reporting from poisoned write methods
+  sIsEnabled = true;
+
+  // Make sure we only poison writes once!
+  static bool WritesArePoisoned = false;
+  if (WritesArePoisoned) {
+    return;
+  }
+  WritesArePoisoned = true;
+
+  // stdout and stderr are OK.
+  MozillaRegisterDebugFD(1);
+  MozillaRegisterDebugFD(2);
+
+#ifdef MOZ_REPLACE_MALLOC
+  // The contract with InitDebugFd is that the given registry can be used
+  // at any moment, so the instance needs to persist longer than the scope
+  // of this functions.
+  static DebugFdRegistry registry;
+  ReplaceMalloc::InitDebugFd(registry);
+#endif
+
+  for (int i = 0; i < NumFunctions; ++i) {
+    FuncData* d = Functions[i];
+    if (!d->Function) {
+      d->Function = dlsym(RTLD_DEFAULT, d->Name);
+    }
+    if (!d->Function) {
+      continue;
+    }
+#ifndef __aarch64__
+    DebugOnly<mach_error_t> t =
+        mach_override_ptr(d->Function, d->Wrapper, &d->Buffer);
+    MOZ_ASSERT(t == err_none);
+#endif
+  }
+}
+
+void OnlyReportDirtyWrites() { sOnlyReportDirtyWrites = true; }
+
+// Never called! See bug 1647107.
+void ClearPoisonIOInterposer() {
+  // Not sure how or if we can unpoison the functions. Would be nice, but no
+  // worries we won't need to do this anyway.
+  sIsEnabled = false;
+}
+
+}  // namespace mozilla