1 // Copyright 2015 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_NAMESPACE_UTILS_H_ 6 #define SANDBOX_LINUX_SERVICES_NAMESPACE_UTILS_H_ 7 8 #include <sys/types.h> 9 10 #include <type_traits> 11 12 #include "base/compiler_specific.h" 13 #include "base/macros.h" 14 #include "sandbox/sandbox_export.h" 15 16 namespace sandbox { 17 18 // Utility functions for using Linux namepaces. 19 class SANDBOX_EXPORT NamespaceUtils { 20 public: 21 static_assert(std::is_same<uid_t, gid_t>::value, 22 "uid_t and gid_t must be the same type"); 23 // generic_id_t can be used for either uid_t or gid_t. 24 typedef uid_t generic_id_t; 25 26 // Write a uid or gid mapping from |id| to |id| in |map_file|. This function 27 // is async-signal-safe. 28 static bool WriteToIdMapFile(const char* map_file, 29 generic_id_t id) WARN_UNUSED_RESULT; 30 31 // Returns true if unprivileged namespaces of type |type| is supported 32 // (meaning that both CLONE_NEWUSER and type are are supported). |type| must 33 // be one of CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWNS, CLONE_NEWPID, 34 // CLONE_NEWUSER, or CLONE_NEWUTS. This relies on access to /proc, so it will 35 // not work from within a sandbox. 36 static bool KernelSupportsUnprivilegedNamespace(int type); 37 38 // Returns true if the kernel supports denying setgroups in a user namespace. 39 // On kernels where this is supported, DenySetgroups must be called before a 40 // gid mapping can be added. 41 static bool KernelSupportsDenySetgroups(); 42 43 // Disables setgroups() within the current user namespace. On Linux 3.18.2 and 44 // later, this is required in order to write to /proc/self/gid_map without 45 // having CAP_SETGID. Callers can determine whether is this needed with 46 // KernelSupportsDenySetgroups. This function is async-signal-safe. 47 static bool DenySetgroups() WARN_UNUSED_RESULT; 48 49 private: 50 DISALLOW_IMPLICIT_CONSTRUCTORS(NamespaceUtils); 51 }; 52 53 } // namespace sandbox 54 55 #endif // SANDBOX_LINUX_SERVICES_NAMESPACE_UTILS_H_ 56
