b3b14b97b1
Propagation type changes must be done as a separate call, in the same way as read only bind mounts. To fix this: 1. Ensure propagation type change flags aren't included in other calls. 2. Apply propagation type change in a separate call. Also: * Make it clear which parameters are ignored by passing them as empty. * Add tests to ensure Mount options are applied correctly. Fixes #30415 Signed-off-by: Steven Hartland <steven.hartland@multiplay.co.uk>
56 lines
1.5 KiB
Go
56 lines
1.5 KiB
Go
package mount
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import (
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"syscall"
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)
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const (
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// ptypes is the set propagation types.
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ptypes = syscall.MS_SHARED | syscall.MS_PRIVATE | syscall.MS_SLAVE | syscall.MS_UNBINDABLE
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// pflags is the full set valid flags for a change propagation call.
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pflags = ptypes | syscall.MS_REC | syscall.MS_SILENT
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// broflags is the combination of bind and read only
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broflags = syscall.MS_BIND | syscall.MS_RDONLY
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)
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// isremount returns true if either device name or flags identify a remount request, false otherwise.
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func isremount(device string, flags uintptr) bool {
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switch {
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// We treat device "" and "none" as a remount request to provide compatibility with
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// requests that don't explicitly set MS_REMOUNT such as those manipulating bind mounts.
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case flags&syscall.MS_REMOUNT != 0, device == "", device == "none":
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return true
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default:
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return false
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}
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}
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func mount(device, target, mType string, flags uintptr, data string) error {
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oflags := flags &^ ptypes
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if !isremount(device, flags) {
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// Initial call applying all non-propagation flags.
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if err := syscall.Mount(device, target, mType, oflags, data); err != nil {
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return err
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}
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}
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if flags&ptypes != 0 {
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// Change the propagation type.
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if err := syscall.Mount("", target, "", flags&pflags, ""); err != nil {
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return err
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}
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}
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if oflags&broflags == broflags {
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// Remount the bind to apply read only.
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return syscall.Mount("", target, "", oflags|syscall.MS_REMOUNT, "")
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}
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return nil
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}
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func unmount(target string, flag int) error {
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return syscall.Unmount(target, flag)
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}
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