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