libct/userns: split userns detection from internal userns code

Commit 4316df8 isolated RunningInUserNS
to a separate package to make it easier to consume without bringing in
additional dependencies, and with the potential to move it separate in
a similar fashion as libcontainer/user was moved to a separate module
in commit ca32014. While RunningInUserNS
is fairly trivial to implement, it (or variants of this utility) is used
in many codebases, and moving to a separate module could consolidate
those implementations, as well as making it easier to consume without
large dependency trees (when being a package as part of a larger code
base).

Commit 1912d59 and follow-ups introduced
cgo code into the userns package, and code introduced in those commits
are not intended for external use, therefore complicating the potential
of moving the userns package separate.

This commit moves the new code to a separate package; some of this code
was included in v1.1.11 and up, but I could not find external consumers
of `GetUserNamespaceMappings` and `IsSameMapping`. The `Mapping` and
`Handles` types (added in ba0b5e2) only
exist in main and in non-stable releases (v1.2.0-rc.x), so don't need
an alias / deprecation.

Signed-off-by: Sebastiaan van Stijn <[email protected]>

Author: thaJeztah

libcontainer/integration/exec_test.go

@@ -18,7 +18,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
 	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/libcontainer/userns"
+	"github.com/opencontainers/runc/libcontainer/internal/userns"
 	"github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/opencontainers/runtime-spec/specs-go"
 
@@ -724,7 +724,7 @@ func TestContainerState(t *testing.T) {
 		{Type: configs.NEWNS},
 		{Type: configs.NEWUTS},
 		// host for IPC
-		//{Type: configs.NEWIPC},
+		// {Type: configs.NEWIPC},
 		{Type: configs.NEWPID},
 		{Type: configs.NEWNET},
 	})

libcontainer/userns/userns_maps.c renamed to libcontainer/internal/userns/userns_maps.c

@@ -11,7 +11,7 @@ import (
 	"golang.org/x/sys/unix"
 
 	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/libcontainer/userns"
+	"github.com/opencontainers/runc/libcontainer/internal/userns"
 	"github.com/opencontainers/runc/libcontainer/utils"
 )
 

libcontainer/userns/userns_maps_linux.go renamed to libcontainer/internal/userns/userns_maps_linux.go

@@ -23,9 +23,9 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups/fs2"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/intelrdt"
+	"github.com/opencontainers/runc/libcontainer/internal/userns"
 	"github.com/opencontainers/runc/libcontainer/logs"
 	"github.com/opencontainers/runc/libcontainer/system"
-	"github.com/opencontainers/runc/libcontainer/userns"
 	"github.com/opencontainers/runc/libcontainer/utils"
 )
 

libcontainer/userns/usernsfd_linux.go renamed to libcontainer/internal/userns/usernsfd_linux.go

@@ -17,8 +17,8 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/devices"
+	"github.com/opencontainers/runc/libcontainer/internal/userns"
 	"github.com/opencontainers/runc/libcontainer/seccomp"
-	"github.com/opencontainers/runc/libcontainer/userns"
 	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"