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-rw-r--r--pkg/rootless/rootless_linux.go91
1 files changed, 1 insertions, 90 deletions
diff --git a/pkg/rootless/rootless_linux.go b/pkg/rootless/rootless_linux.go
index 5ddfab7ad..f01ebe5fc 100644
--- a/pkg/rootless/rootless_linux.go
+++ b/pkg/rootless/rootless_linux.go
@@ -124,91 +124,6 @@ func tryMappingTool(tool string, pid int, hostID int, mappings []idtools.IDMap)
return nil
}
-func readUserNs(path string) (string, error) {
- b := make([]byte, 256)
- _, err := unix.Readlink(path, b)
- if err != nil {
- return "", err
- }
- return string(b), nil
-}
-
-func readUserNsFd(fd uintptr) (string, error) {
- return readUserNs(fmt.Sprintf("/proc/self/fd/%d", fd))
-}
-
-func getParentUserNs(fd uintptr) (uintptr, error) {
- const nsGetParent = 0xb702
- ret, _, errno := unix.Syscall(unix.SYS_IOCTL, fd, uintptr(nsGetParent), 0)
- if errno != 0 {
- return 0, errno
- }
- return (uintptr)(unsafe.Pointer(ret)), nil
-}
-
-// getUserNSFirstChild returns an open FD for the first direct child user namespace that created the process
-// Each container creates a new user namespace where the runtime runs. The current process in the container
-// might have created new user namespaces that are child of the initial namespace we created.
-// This function finds the initial namespace created for the container that is a child of the current namespace.
-//
-// current ns
-// / \
-// TARGET -> a [other containers]
-// /
-// b
-// /
-// NS READ USING THE PID -> c
-func getUserNSFirstChild(fd uintptr) (*os.File, error) {
- currentNS, err := readUserNs("/proc/self/ns/user")
- if err != nil {
- return nil, err
- }
-
- ns, err := readUserNsFd(fd)
- if err != nil {
- return nil, errors.Wrapf(err, "cannot read user namespace")
- }
- if ns == currentNS {
- return nil, errors.New("process running in the same user namespace")
- }
-
- for {
- nextFd, err := getParentUserNs(fd)
- if err != nil {
- if err == unix.ENOTTY {
- return os.NewFile(fd, "userns child"), nil
- }
- return nil, errors.Wrapf(err, "cannot get parent user namespace")
- }
-
- ns, err = readUserNsFd(nextFd)
- if err != nil {
- return nil, errors.Wrapf(err, "cannot read user namespace")
- }
-
- if ns == currentNS {
- if err := unix.Close(int(nextFd)); err != nil {
- return nil, err
- }
-
- // Drop O_CLOEXEC for the fd.
- _, _, errno := unix.Syscall(unix.SYS_FCNTL, fd, unix.F_SETFD, 0)
- if errno != 0 {
- if err := unix.Close(int(fd)); err != nil {
- logrus.Errorf("failed to close file descriptor %d", fd)
- }
- return nil, errno
- }
-
- return os.NewFile(fd, "userns child"), nil
- }
- if err := unix.Close(int(fd)); err != nil {
- return nil, err
- }
- fd = nextFd
- }
-}
-
// joinUserAndMountNS re-exec podman in a new userNS and join the user and mount
// namespace of the specified PID without looking up its parent. Useful to join directly
// the conmon process.
@@ -240,11 +155,7 @@ func joinUserAndMountNS(pid uint, pausePid string) (bool, int, error) {
}
}()
- fd, err := getUserNSFirstChild(userNS.Fd())
- if err != nil {
- return false, -1, err
- }
- pidC := C.reexec_userns_join(C.int(fd.Fd()), C.int(mountNS.Fd()), cPausePid)
+ pidC := C.reexec_userns_join(C.int(userNS.Fd()), C.int(mountNS.Fd()), cPausePid)
if int(pidC) < 0 {
return false, -1, errors.Errorf("cannot re-exec process")
}