1 files changed, 137 insertions, 0 deletions
diff --git a/security/sandbox/linux/glue/SandboxCrash.cpp b/security/sandbox/linux/glue/SandboxCrash.cpp
new file mode 100644
index 000000000..87a75e845
--- /dev/null
+++ b/security/sandbox/linux/glue/SandboxCrash.cpp
@@ -0,0 +1,137 @@
+/* -*- 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/. */
+
+// This file needs to be linked into libxul, so it can access the JS
+// stack and the crash reporter.  Everything else in this directory
+// should be able to be linked into its own shared library, in order
+// to be able to isolate sandbox/chromium from ipc/chromium.
+
+#include "SandboxInternal.h"
+#include "SandboxLogging.h"
+
+#include <unistd.h>
+#include <sys/syscall.h>
+
+#include "mozilla/Unused.h"
+#include "mozilla/dom/Exceptions.h"
+#include "nsContentUtils.h"
+#ifdef MOZ_CRASHREPORTER
+#include "nsExceptionHandler.h"
+#endif
+#include "mozilla/StackWalk.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+// Log JS stack info in the same place as the sandbox violation
+// message.  Useful in case the responsible code is JS and all we have
+// are logs and a minidump with the C++ stacks (e.g., on TBPL).
+static void
+SandboxLogJSStack(void)
+{
+  if (!NS_IsMainThread()) {
+    // This might be a worker thread... or it might be a non-JS
+    // thread, or a non-NSPR thread.  There's isn't a good API for
+    // dealing with this, yet.
+    return;
+  }
+  if (!nsContentUtils::XPConnect()) {
+    // There is no content (e.g., the process is a media plugin), in
+    // which case this will probably crash and definitely not work.
+    return;
+  }
+  nsCOMPtr<nsIStackFrame> frame = dom::GetCurrentJSStack();
+  // If we got a stack, we must have a current JSContext.  This is icky.  :(
+  // Would be better if GetCurrentJSStack() handed out the JSContext it ended up
+  // using or something.
+  JSContext* cx = frame ? nsContentUtils::GetCurrentJSContext() : nullptr;
+  for (int i = 0; frame != nullptr; ++i) {
+    nsAutoString fileName, funName;
+    int32_t lineNumber;
+
+    // Don't stop unwinding if an attribute can't be read.
+    fileName.SetIsVoid(true);
+    Unused << frame->GetFilename(cx, fileName);
+    lineNumber = 0;
+    Unused << frame->GetLineNumber(cx, &lineNumber);
+    funName.SetIsVoid(true);
+    Unused << frame->GetName(cx, funName);
+
+    if (!funName.IsVoid() || !fileName.IsVoid()) {
+      SANDBOX_LOG_ERROR("JS frame %d: %s %s line %d", i,
+                        funName.IsVoid() ?
+                        "(anonymous)" : NS_ConvertUTF16toUTF8(funName).get(),
+                        fileName.IsVoid() ?
+                        "(no file)" : NS_ConvertUTF16toUTF8(fileName).get(),
+                        lineNumber);
+    }
+
+    nsCOMPtr<nsIStackFrame> nextFrame;
+    nsresult rv = frame->GetCaller(cx, getter_AddRefs(nextFrame));
+    NS_ENSURE_SUCCESS_VOID(rv);
+    frame = nextFrame;
+  }
+}
+
+static void SandboxPrintStackFrame(uint32_t aFrameNumber, void *aPC, void *aSP,
+                                   void *aClosure)
+{
+  char buf[1024];
+  MozCodeAddressDetails details;
+
+  MozDescribeCodeAddress(aPC, &details);
+  MozFormatCodeAddressDetails(buf, sizeof(buf), aFrameNumber, aPC, &details);
+  SANDBOX_LOG_ERROR("frame %s", buf);
+}
+
+static void
+SandboxLogCStack()
+{
+  // Skip 3 frames: one for this module, one for the signal handler in
+  // libmozsandbox, and one for the signal trampoline.
+  //
+  // Warning: this might not print any stack frames.  MozStackWalk
+  // can't walk past the signal trampoline on ARM (bug 968531), and
+  // x86 frame pointer walking may or may not work (bug 1082276).
+
+  MozStackWalk(SandboxPrintStackFrame, /* skip */ 3, /* max */ 0,
+               nullptr, 0, nullptr);
+  SANDBOX_LOG_ERROR("end of stack.");
+}
+
+static void
+SandboxCrash(int nr, siginfo_t *info, void *void_context)
+{
+  pid_t pid = getpid(), tid = syscall(__NR_gettid);
+  bool dumped = false;
+
+#ifdef MOZ_CRASHREPORTER
+  dumped = CrashReporter::WriteMinidumpForSigInfo(nr, info, void_context);
+#endif
+  if (!dumped) {
+    SANDBOX_LOG_ERROR("crash reporter is disabled (or failed);"
+                      " trying stack trace:");
+    SandboxLogCStack();
+  }
+
+  // Do this last, in case it crashes or deadlocks.
+  SandboxLogJSStack();
+
+  // Try to reraise, so the parent sees that this process crashed.
+  // (If tgkill is forbidden, then seccomp will raise SIGSYS, which
+  // also accomplishes that goal.)
+  signal(SIGSYS, SIG_DFL);
+  syscall(__NR_tgkill, pid, tid, nr);
+}
+
+static void __attribute__((constructor))
+SandboxSetCrashFunc()
+{
+  gSandboxCrashFunc = SandboxCrash;
+}
+
+} // namespace mozilla