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Fixed subpath in containerized kubelet.

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IsNotMountPoint should return no error when the checked directory does not
exists - missing directory can't be mounted. Therefore containerized
kubelet should check if the target exists first before resolving symlinks.
EvalHostSymlinks() returns indistinguishible error in case the path does
not exist.
This commit is contained in:
Jan Safranek 2018-10-09 13:11:23 +02:00
parent 9ba74cb5b5
commit 0b8c472578
2 changed files with 21 additions and 12 deletions
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14
pkg/util/mount/mount.go
View File

@ -251,14 +251,9 @@ func GetDeviceNameFromMount(mounter Interface, mountPath string) (string, int, e
// It is more extensive than IsLikelyNotMountPoint
// and it detects bind mounts in linux
func IsNotMountPoint(mounter Interface, file string) (bool, error) {
// Resolve any symlinks in file, kernel would do the same and use the resolved path in /proc/mounts
resolvedFile, err := mounter.EvalHostSymlinks(file)
if err != nil {
return true, err
}
// IsLikelyNotMountPoint provides a quick check
// to determine whether file IS A mountpoint
notMnt, notMntErr := mounter.IsLikelyNotMountPoint(resolvedFile)
notMnt, notMntErr := mounter.IsLikelyNotMountPoint(file)
if notMntErr != nil && os.IsPermission(notMntErr) {
// We were not allowed to do the simple stat() check, e.g. on NFS with
// root_squash. Fall back to /proc/mounts check below.
@ -272,6 +267,13 @@ func IsNotMountPoint(mounter Interface, file string) (bool, error) {
if notMnt == false {
return notMnt, nil
}
// Resolve any symlinks in file, kernel would do the same and use the resolved path in /proc/mounts
resolvedFile, err := mounter.EvalHostSymlinks(file)
if err != nil {
return true, err
}
// check all mountpoints since IsLikelyNotMountPoint
// is not reliable for some mountpoint types
mountPoints, mountPointsErr := mounter.List()

19
pkg/util/mount/nsenter_mount.go
View File

@ -166,15 +166,22 @@ func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
glog.V(5).Infof("findmnt: directory %s does not exist", file)
return true, err
}
// Resolve any symlinks in file, kernel would do the same and use the resolved path in /proc/mounts
resolvedFile, err := n.EvalHostSymlinks(file)
if err != nil {
return true, err
}
// Add --first-only option: since we are testing for the absence of a mountpoint, it is sufficient to get only
// the first of multiple possible mountpoints using --first-only.
// Also add fstype output to make sure that the output of target file will give the full path
// TODO: Need more refactoring for this function. Track the solution with issue #26996
args := []string{"-o", "target,fstype", "--noheadings", "--first-only", "--target", file}
args := []string{"-o", "target,fstype", "--noheadings", "--first-only", "--target", resolvedFile}
glog.V(5).Infof("nsenter findmnt args: %v", args)
out, err := n.ne.Exec("findmnt", args).CombinedOutput()
if err != nil {
glog.V(2).Infof("Failed findmnt command for path %s: %s %v", file, out, err)
glog.V(2).Infof("Failed findmnt command for path %s: %s %v", resolvedFile, out, err)
// Different operating systems behave differently for paths which are not mount points.
// On older versions (e.g. 2.20.1) we'd get error, on newer ones (e.g. 2.26.2) we'd get "/".
// It's safer to assume that it's not a mount point.
@ -185,13 +192,13 @@ func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
return false, err
}
glog.V(5).Infof("IsLikelyNotMountPoint findmnt output for path %s: %v:", file, mountTarget)
glog.V(5).Infof("IsLikelyNotMountPoint findmnt output for path %s: %v:", resolvedFile, mountTarget)
if mountTarget == file {
glog.V(5).Infof("IsLikelyNotMountPoint: %s is a mount point", file)
if mountTarget == resolvedFile {
glog.V(5).Infof("IsLikelyNotMountPoint: %s is a mount point", resolvedFile)
return false, nil
}
glog.V(5).Infof("IsLikelyNotMountPoint: %s is not a mount point", file)
glog.V(5).Infof("IsLikelyNotMountPoint: %s is not a mount point", resolvedFile)
return true, nil
}