feature: cross-container named pipes

Add support for cross-container pipes for Xenon WCOW
containers.

Extend the logic of `IsPipe` and `GetContainerPipeMapping` to
also handle cross-container pipes within the UVM. The syntax
is the same as for sandbox mounts:

```
{
  "host_path": "sandbox://\\\\.\\pipe\\uvmPipe",
  "container_path": "\\\\.\\pipe\\containerPipe"
}
```

Containers sharing the pipe need to have the same "host_path".

Signed-off-by: Maksim An <maksiman@microsoft.com>

internal/hcsoci/hcsdoc_wcow.go

@@ -69,7 +69,7 @@ func createMountsConfig(ctx context.Context, coi *createOptionsInternal) (*mount
 				}
 				mdv2.HostPath = src
 			} else if mount.Type == MountTypeVirtualDisk || mount.Type == MountTypePhysicalDisk || mount.Type == MountTypeExtensibleVirtualDisk {
-				// For v2 schema containers, any disk mounts will be part of coi.additionalMounts.
+				// For v2 schema containers, any disk mounts will be part of coi.windowsAdditionalMounts.
 				// For v1 schema containers, we don't even get here, since there is no HostingSystem.
 				continue
 			} else if strings.HasPrefix(mount.Source, guestpath.SandboxMountPrefix) {

internal/hcsoci/resources_wcow.go

@@ -181,9 +181,16 @@ func setupMounts(ctx context.Context, coi *createOptionsInternal, r *resources.R
 			} else if strings.HasPrefix(mount.Source, guestpath.SandboxMountPrefix) {
 				// Mounts that map to a path in the UVM are specified with a 'sandbox://' prefix.
 				//
-				// Example: sandbox:///a/dirInUvm destination:C:\\dirInContainer.
+				// Example:
+				//   - sandbox:///a/dirInUvm destination:C:\\dirInContainer.
+				//   - sandbox://\\.\pipe\uvmNamedPipe destination: \\.\pipe\containerNamedPipe
 				//
 				// so first convert to a path in the sandboxmounts path itself.
+				if uvm.IsPipe(mount.Source) {
+					// When mapping UVM named pipe into container, we don't need to do anything else, since it'll be
+					// handled via `createMountsConfig`.
+					continue
+				}
 				sandboxPath := convertToWCOWSandboxMountPath(mount.Source)
 
 				// Now we need to exec a process in the vm that will make these directories as theres

internal/uvm/pipes.go

@@ -7,10 +7,11 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/Microsoft/hcsshim/internal/guestpath"
 	"github.com/Microsoft/hcsshim/internal/hcs/resourcepaths"
 	hcsschema "github.com/Microsoft/hcsshim/internal/hcs/schema2"
 	"github.com/Microsoft/hcsshim/internal/protocol/guestrequest"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/opencontainers/runtime-spec/specs-go"
 )
 
 const pipePrefix = `\\.\pipe\`
@@ -54,18 +55,38 @@ func (uvm *UtilityVM) RemovePipe(ctx context.Context, hostPath string) error {
 	return nil
 }
 
-// IsPipe returns true if the given path references a named pipe.
+// SandboxNamedPipe returns a named pipe in UVM, which will be shared across containers.
+func (uvm *UtilityVM) SandboxNamedPipe(hostPath string) string {
+	podID := strings.TrimPrefix(uvm.id, "@vm")
+	if uvm.operatingSystem == "windows" {
+		uvmPipeName := strings.TrimPrefix(hostPath, pipePrefix)
+		return fmt.Sprintf(`%s%s\%s`, pipePrefix, podID, uvmPipeName)
+	}
+	return fmt.Sprintf("%s-%s", podID, hostPath)
+}
+
+// IsPipe returns true if the given path references a named pipe. The pipe can be:
+// - host named pipe shared via VSMB
+// - UVM named pipe
 func IsPipe(hostPath string) bool {
+	if sandboxMount, ok := strings.CutPrefix(hostPath, guestpath.SandboxMountPrefix); ok {
+		return strings.HasPrefix(sandboxMount, pipePrefix)
+	}
 	return strings.HasPrefix(hostPath, pipePrefix)
 }
 
 // GetContainerPipeMapping returns the source and destination to use for a given
 // pipe mount in a container.
+// The pipe mount can be either a host pipe shared via VSMB or a UVM pipe.
 func GetContainerPipeMapping(uvm *UtilityVM, mount specs.Mount) (src string, dst string) {
 	if uvm == nil {
 		src = mount.Source
 	} else {
-		src = vsmbSharePrefix + `IPC$\` + strings.TrimPrefix(mount.Source, pipePrefix)
+		if uvmPipe, ok := strings.CutPrefix(mount.Source, guestpath.SandboxMountPrefix); ok {
+			src = uvm.SandboxNamedPipe(uvmPipe)
+		} else {
+			src = vsmbSharePrefix + `IPC$\` + strings.TrimPrefix(mount.Source, pipePrefix)
+		}
 	}
 	dst = strings.TrimPrefix(mount.Destination, pipePrefix)
 	return src, dst