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.
5 #ifndef SANDBOX_LINUX_SERVICES_NAMESPACE_SANDBOX_H_
6 #define SANDBOX_LINUX_SERVICES_NAMESPACE_SANDBOX_H_
13 #include "base/command_line.h"
14 #include "base/macros.h"
15 #include "base/process/launch.h"
16 #include "base/process/process.h"
17 #include "sandbox/sandbox_export.h"
21 // Helper class for starting a process inside a new user, PID, and network
22 // namespace. Before using a namespace sandbox, check for namespaces support
23 // using Credentials::CanCreateProcessInNewUserNS.
25 // A typical use for "A" launching a sandboxed process "B" would be:
26 // 1. A sets up a command line and launch options for process B.
27 // 2. A launches B with LaunchProcess.
28 // 3. B should be prepared to assume the role of init(1). In particular, apart
29 // from SIGKILL and SIGSTOP, B cannot receive any signal for which it does
30 // not have an explicit signal handler registered.
31 // If B dies, all the processes in the namespace will die.
32 // B can fork() and the parent can assume the role of init(1), by using
33 // CreateInitProcessReaper().
34 // 4. B chroots using Credentials::MoveToNewUserNS() and
35 // Credentials::DropFileSystemAccess()
36 // 5. B drops capabilities gained by entering the new user namespace with
37 // Credentials::DropAllCapabilities().
38 class SANDBOX_EXPORT NamespaceSandbox
{
40 #if !defined(OS_NACL_NONSFI)
45 // Bitmask of namespace types. Must be some combination of CLONE_NEWUSER
46 // (required), CLONE_NEWPID, and CLONE_NEWNET. Defaults to all of the above.
49 // Fail if any of the namespace types are not supported. Defaults to false.
50 bool fail_on_unsupported_ns_type
;
53 // Launch a new process inside its own user/PID/network namespaces (depending
54 // on kernel support). Requires at a minimum that user namespaces are
55 // supported (use Credentials::CanCreateProcessInNewUserNS to check this).
57 // pre_exec_delegate and clone_flags fields of LaunchOptions should be nullptr
58 // and 0, respectively, since this function makes a copy of options and
60 static base::Process
LaunchProcess(const base::CommandLine
& cmdline
,
61 const base::LaunchOptions
& launch_options
);
62 static base::Process
LaunchProcess(const std::vector
<std::string
>& argv
,
63 const base::LaunchOptions
& launch_options
);
65 // Versions which take namespace sandbox options. These allow fine grained
66 // control over the types of namespaces used.
67 static base::Process
LaunchProcessWithOptions(
68 const base::CommandLine
& cmdline
,
69 const base::LaunchOptions
& launch_options
,
70 const Options
& ns_sandbox_options
);
71 static base::Process
LaunchProcessWithOptions(
72 const std::vector
<std::string
>& argv
,
73 const base::LaunchOptions
& launch_options
,
74 const Options
& ns_sandbox_options
);
75 #endif // !defined(OS_NACL_NONSFI)
77 // Forks a process in its own PID namespace. The child process is the init
78 // process inside of the PID namespace, so if the child needs to fork further,
79 // it should call CreateInitProcessReaper, which turns the init process into a
82 // Otherwise, the child should setup handlers for signals which should
83 // terminate the process using InstallDefaultTerminationSignalHandlers or
84 // InstallTerminationSignalHandler. This works around the fact that init
85 // processes ignore such signals unless they have an explicit handler set.
87 // This function requries CAP_SYS_ADMIN. If |drop_capabilities_in_child| is
88 // true, then capabilities are dropped in the child.
89 static pid_t
ForkInNewPidNamespace(bool drop_capabilities_in_child
);
91 // Installs a signal handler for:
93 // SIGHUP, SIGINT, SIGABRT, SIGQUIT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
95 // that exits with SignalExitCode(sig). These are signals whose default action
96 // is to terminate the program (apart from SIGILL, SIGFPE, and SIGSEGV, which
97 // will still terminate the process if e.g. an illegal instruction is
98 // encountered, etc.).
100 // If any of these already had a signal handler installed, this function will
101 // not override them.
102 static void InstallDefaultTerminationSignalHandlers();
104 // Installs a signal handler for |sig| which exits with |exit_code|. If a
105 // signal handler was already present for |sig|, does nothing and returns
107 static bool InstallTerminationSignalHandler(int sig
, int exit_code
);
109 // Returns an exit code corresponding to the process being killed by sig. This
110 // is the same as exit code that NaCl's default signal handler uses.
111 static int SignalExitCode(int sig
) { return -sig
& 0xff; }
113 // Returns whether the namespace sandbox created a new user, PID, and network
114 // namespace. In particular, InNewUserNamespace should return true iff the
115 // process was started via this class.
116 static bool InNewUserNamespace();
117 static bool InNewPidNamespace();
118 static bool InNewNetNamespace();
121 DISALLOW_IMPLICIT_CONSTRUCTORS(NamespaceSandbox
);
124 } // namespace sandbox
126 #endif // SANDBOX_LINUX_SERVICES_NAMESPACE_SANDBOX_H_