oci/deviceFromPath(): correctly check device types

This ports the changes of opencontainers/runc@95a59bf
to this repository.

From that PR:

    (mode&S_IFCHR == S_IFCHR) is the wrong way of checking the type of an
    inode because the S_IF* bits are actually not a bitmask and instead must
    be checked using S_IF*. This bug was neatly hidden behind a (major == 0)
    sanity-check but that was removed by [1].

    In addition, add a test that makes sure that HostDevices() doesn't give
    rubbish results -- because we broke this and fixed this before[2].

    [1]: opencontainers/runc@24388be ("configs: use different types for .Devices and .Resources.Devices")
    [2]: opencontainers/runc@3ed492a ("Handle non-devices correctly in DeviceFromPath")

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

oci/utils_unix.go

@@ -91,6 +91,9 @@ func getDevices(path, containerPath string) ([]specs.LinuxDevice, error) {
 			}
 			return nil, err
 		}
+		if device.Type == fifoDevice {
+			continue
+		}
 		if containerPath != "" {
 			device.Path = filepath.Join(containerPath, filepath.Base(f.Name()))
 		}
@@ -99,6 +102,14 @@ func getDevices(path, containerPath string) ([]specs.LinuxDevice, error) {
 	return out, nil
 }
 
+// TODO consider adding these consts to the OCI runtime-spec.
+const (
+	wildcardDevice = "a" //nolint // currently unused, but should be included when upstreaming to OCI runtime-spec.
+	blockDevice    = "b"
+	charDevice     = "c" // or "u"
+	fifoDevice     = "p"
+)
+
 func deviceFromPath(path string) (*specs.LinuxDevice, error) {
 	var stat unix.Stat_t
 	if err := unix.Lstat(path, &stat); err != nil {
@@ -110,19 +121,21 @@ func deviceFromPath(path string) (*specs.LinuxDevice, error) {
 		major     = unix.Major(devNumber)
 		minor     = unix.Minor(devNumber)
 	)
-	if major == 0 {
-		return nil, errNotADevice
-	}
 
 	var (
 		devType string
 		mode    = stat.Mode
 	)
-	switch {
-	case mode&unix.S_IFBLK == unix.S_IFBLK:
-		devType = "b"
-	case mode&unix.S_IFCHR == unix.S_IFCHR:
-		devType = "c"
+
+	switch mode & unix.S_IFMT {
+	case unix.S_IFBLK:
+		devType = blockDevice
+	case unix.S_IFCHR:
+		devType = charDevice
+	case unix.S_IFIFO:
+		devType = fifoDevice
+	default:
+		return nil, errNotADevice
 	}
 	fm := os.FileMode(mode &^ unix.S_IFMT)
 	return &specs.LinuxDevice{

oci/utils_unix_test.go

@@ -0,0 +1,44 @@
+//go:build !windows && !darwin
+// +build !windows,!darwin
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import "testing"
+
+func TestHostDevicesAllValid(t *testing.T) {
+	devices, err := HostDevices()
+	if err != nil {
+		t.Fatalf("failed to get host devices: %v", err)
+	}
+
+	for _, device := range devices {
+		// Devices can't have major number 0.
+		if device.Major == 0 {
+			t.Errorf("device entry %+v has zero major number", device)
+		}
+		switch device.Type {
+		case blockDevice, charDevice:
+		case fifoDevice:
+			t.Logf("fifo devices shouldn't show up from HostDevices")
+			fallthrough
+		default:
+			t.Errorf("device entry %+v has unexpected type %v", device, device.Type)
+		}
+	}
+}