1 files changed, 105 insertions, 0 deletions
diff --git a/sandbox/linux/seccomp/securemem.cc b/sandbox/linux/seccomp/securemem.cc
new file mode 100644
index 0000000..5f07bbe
--- /dev/null
+++ b/sandbox/linux/seccomp/securemem.cc
@@ -0,0 +1,105 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "debug.h"
+#include "mutex.h"
+#include "sandbox_impl.h"
+#include "securemem.h"
+
+namespace playground {
+
+void SecureMem::abandonSystemCall(int fd, int err) {
+  void* rc = reinterpret_cast<void *>(err);
+  if (err) {
+    Debug::message("System call failed\n");
+  }
+  Sandbox::SysCalls sys;
+  if (Sandbox::write(sys, fd, &rc, sizeof(rc)) != sizeof(rc)) {
+    Sandbox::die("Failed to send system call");
+  }
+}
+
+void SecureMem::dieIfParentDied(int parentMapsFd) {
+  // The syscall_mutex_ should not be contended. If it is, we are either
+  // experiencing a very unusual load of system calls that the sandbox is not
+  // optimized for; or, more likely, the sandboxed process terminated while the
+  // trusted process was in the middle of waiting for the mutex. We detect
+  // this situation and terminate the trusted process.
+  int alive = !lseek(parentMapsFd, 0, SEEK_SET);
+  if (alive) {
+    char buf;
+    do {
+      alive = read(parentMapsFd, &buf, 1);
+    } while (alive < 0 && errno == EINTR);
+  }
+  if (!alive) {
+    Sandbox::die();
+  }
+}
+
+void SecureMem::lockSystemCall(int parentMapsFd, Args* mem) {
+  while (!Mutex::lockMutex(&Sandbox::syscall_mutex_, 500)) {
+    dieIfParentDied(parentMapsFd);
+  }
+  asm volatile(
+  #if defined(__x86_64__)
+      "lock; incq (%0)\n"
+  #elif defined(__i386__)
+      "lock; incl (%0)\n"
+  #else
+  #error Unsupported target platform
+  #endif
+      :
+      : "q"(&mem->sequence)
+      : "memory");
+}
+
+void SecureMem::sendSystemCallInternal(int fd, bool locked, int parentMapsFd,
+                                       Args* mem, int syscallNum, void* arg1,
+                                       void* arg2, void* arg3, void* arg4,
+                                       void* arg5, void* arg6) {
+  if (!locked) {
+    asm volatile(
+    #if defined(__x86_64__)
+        "lock; incq (%0)\n"
+    #elif defined(__i386__)
+        "lock; incl (%0)\n"
+    #else
+    #error Unsupported target platform
+    #endif
+        :
+        : "q"(&mem->sequence)
+        : "memory");
+  }
+  mem->callType    = locked ? -2 : -1;
+  mem->syscallNum  = syscallNum;
+  mem->arg1        = arg1;
+  mem->arg2        = arg2;
+  mem->arg3        = arg3;
+  mem->arg4        = arg4;
+  mem->arg5        = arg5;
+  mem->arg6        = arg6;
+  asm volatile(
+  #if defined(__x86_64__)
+      "lock; incq (%0)\n"
+  #elif defined(__i386__)
+      "lock; incl (%0)\n"
+  #else
+  #error Unsupported target platform
+  #endif
+      :
+      : "q"(&mem->sequence)
+      : "memory");
+  Sandbox::SysCalls sys;
+  if (Sandbox::write(sys, fd, &mem->callType, sizeof(int)) != sizeof(int)) {
+    Sandbox::die("Failed to send system call");
+  }
+  if (parentMapsFd >= 0) {
+    while (!Mutex::waitForUnlock(&Sandbox::syscall_mutex_, 500)) {
+      dieIfParentDied(parentMapsFd);
+    }
+  }
+}
+
+} // namespace