gh-95023: Added os.setns and os.unshare functions (#95046)

Added os.setns and os.unshare to easily switch between namespaces
on Linux.

Co-authored-by: Christian Heimes <christian@python.org>
Co-authored-by: CAM Gerlach <CAM.Gerlach@Gerlach.CAM>
Co-authored-by: Victor Stinner <vstinner@python.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 39198cb..56ea319 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -8581,6 +8581,64 @@ os_pidfd_open_impl(PyObject *module, pid_t pid, unsigned int flags)
 #endif
 
 
+#ifdef HAVE_SETNS
+/*[clinic input]
+os.setns
+  fd: fildes
+    A file descriptor to a namespace.
+  nstype: int = 0
+    Type of namespace.
+
+Move the calling thread into different namespaces.
+[clinic start generated code]*/
+
+static PyObject *
+os_setns_impl(PyObject *module, int fd, int nstype)
+/*[clinic end generated code: output=5dbd055bfb66ecd0 input=42787871226bf3ee]*/
+{
+    int res;
+
+    Py_BEGIN_ALLOW_THREADS
+    res = setns(fd, nstype);
+    Py_END_ALLOW_THREADS
+
+    if (res != 0) {
+        return posix_error();
+    }
+
+    Py_RETURN_NONE;
+}
+#endif
+
+
+#ifdef HAVE_UNSHARE
+/*[clinic input]
+os.unshare
+  flags: int
+    Namespaces to be unshared.
+
+Disassociate parts of a process (or thread) execution context.
+[clinic start generated code]*/
+
+static PyObject *
+os_unshare_impl(PyObject *module, int flags)
+/*[clinic end generated code: output=1b3177906dd237ee input=9e065db3232b8b1b]*/
+{
+    int res;
+
+    Py_BEGIN_ALLOW_THREADS
+    res = unshare(flags);
+    Py_END_ALLOW_THREADS
+
+    if (res != 0) {
+        return posix_error();
+    }
+    
+    Py_RETURN_NONE;
+}
+#endif
+
+
 #if defined(HAVE_READLINK) || defined(MS_WINDOWS)
 /*[clinic input]
 os.readlink
@@ -14945,6 +15003,8 @@ static PyMethodDef posix_methods[] = {
     OS__ADD_DLL_DIRECTORY_METHODDEF
     OS__REMOVE_DLL_DIRECTORY_METHODDEF
     OS_WAITSTATUS_TO_EXITCODE_METHODDEF
+    OS_SETNS_METHODDEF
+    OS_UNSHARE_METHODDEF
     {NULL,              NULL}            /* Sentinel */
 };
 
@@ -15390,6 +15450,53 @@ all_ins(PyObject *m)
 #ifdef SCHED_FX
     if (PyModule_AddIntConstant(m, "SCHED_FX", SCHED_FSS)) return -1;
 #endif
+
+/* constants for namespaces */
+#if defined(HAVE_SETNS) || defined(HAVE_UNSHARE)
+#ifdef CLONE_FS
+    if (PyModule_AddIntMacro(m, CLONE_FS)) return -1;
+#endif
+#ifdef CLONE_FILES
+    if (PyModule_AddIntMacro(m, CLONE_FILES)) return -1;
+#endif
+#ifdef CLONE_NEWNS
+    if (PyModule_AddIntMacro(m, CLONE_NEWNS)) return -1;
+#endif
+#ifdef CLONE_NEWCGROUP
+    if (PyModule_AddIntMacro(m, CLONE_NEWCGROUP)) return -1;
+#endif
+#ifdef CLONE_NEWUTS
+    if (PyModule_AddIntMacro(m, CLONE_NEWUTS)) return -1;
+#endif
+#ifdef CLONE_NEWIPC
+    if (PyModule_AddIntMacro(m, CLONE_NEWIPC)) return -1;
+#endif
+#ifdef CLONE_NEWUSER
+    if (PyModule_AddIntMacro(m, CLONE_NEWUSER)) return -1;
+#endif
+#ifdef CLONE_NEWPID
+    if (PyModule_AddIntMacro(m, CLONE_NEWPID)) return -1;
+#endif
+#ifdef CLONE_NEWNET
+    if (PyModule_AddIntMacro(m, CLONE_NEWNET)) return -1;
+#endif
+#ifdef CLONE_NEWTIME
+    if (PyModule_AddIntMacro(m, CLONE_NEWTIME)) return -1;
+#endif
+#ifdef CLONE_SYSVSEM
+    if (PyModule_AddIntMacro(m, CLONE_SYSVSEM)) return -1;
+#endif
+#ifdef CLONE_THREAD
+    if (PyModule_AddIntMacro(m, CLONE_THREAD)) return -1;
+#endif
+#ifdef CLONE_SIGHAND
+    if (PyModule_AddIntMacro(m, CLONE_SIGHAND)) return -1;
+#endif
+#ifdef CLONE_VM
+    if (PyModule_AddIntMacro(m, CLONE_VM)) return -1;
+#endif
+#endif
+
 #endif
 
 #ifdef USE_XATTRS