sandbox/linux/services/yama.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SANDBOX_LINUX_SERVICES_YAMA_H_
   6 #define SANDBOX_LINUX_SERVICES_YAMA_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/process/process_handle.h"
  10 #include "sandbox/sandbox_export.h"
  11
  12 namespace sandbox {
  13
  14 // Yama is a LSM kernel module which can restrict ptrace().
  15 // This class provides ways to detect if Yama is present and enabled
  16 // and to restrict which processes can ptrace the current process.
  17 class SANDBOX_EXPORT Yama {
  18  public:
  19   // This enum should be used to set or check a bitmask.
  20   // A value of 0 would indicate that the status is not known.
  21   enum GlobalStatus {
  22     STATUS_KNOWN = 1 << 0,
  23     STATUS_PRESENT = 1 << 1,
  24     STATUS_ENFORCING = 1 << 2,
  25     // STATUS_STRICT_ENFORCING corresponds to either mode 2 or mode 3 of Yama.
  26     // Ptrace could be entirely denied, or restricted to CAP_SYS_PTRACE
  27     // and PTRACE_TRACEME.
  28     STATUS_STRICT_ENFORCING = 1 << 3
  29   };
  30
  31   // Restrict who can ptrace() the current process to its ancestors.
  32   // If this succeeds, then Yama is available on this kernel.
  33   // However, Yama may not be enforcing at this time.
  34   static bool RestrictPtracersToAncestors();
  35
  36   // Disable Yama restrictions for the current process.
  37   // This will fail if Yama is not available on this kernel.
  38   // This is meant for testing only. If you need this, implement
  39   // a per-pid authorization instead.
  40   static bool DisableYamaRestrictions();
  41
  42   // Checks if Yama is currently in enforcing mode for the machine (not the
  43   // current process). This requires access to the filesystem and will use
  44   // /proc/sys/kernel/yama/ptrace_scope.
  45   static int GetStatus();
  46
  47   // Helper for checking for STATUS_PRESENT in GetStatus().
  48   static bool IsPresent();
  49   // Helper for checkking for STATUS_ENFORCING in GetStatus().
  50   static bool IsEnforcing();
  51
  52  private:
  53   DISALLOW_IMPLICIT_CONSTRUCTORS(Yama);
  54 };
  55
  56 }  // namespace sandbox
  57
  58 #endif  // SANDBOX_LINUX_SERVICES_YAMA_H_