merge branch 'pr-3004'

Sebastiaan van Stijn (2):
  libcontainer: relax validation for absolute paths
  configs/validator: move cgroup validation to the list of checks

LGTMs: kolyshkin cyphar
Closes #3004

libcontainer/configs/validate/validator.go

@@ -12,6 +12,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/intelrdt"
 	selinux "github.com/opencontainers/selinux/go-selinux"
+	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 )
 
@@ -29,6 +30,7 @@ type check func(config *configs.Config) error
 
 func (v *ConfigValidator) Validate(config *configs.Config) error {
 	checks := []check{
+		v.cgroups,
 		v.rootfs,
 		v.network,
 		v.hostname,
@@ -38,17 +40,21 @@ func (v *ConfigValidator) Validate(config *configs.Config) error {
 		v.sysctl,
 		v.intelrdt,
 		v.rootlessEUID,
-		v.mounts,
 	}
 	for _, c := range checks {
 		if err := c(config); err != nil {
 			return err
 		}
 	}
-	if err := v.cgroups(config); err != nil {
-		return err
+	// Relaxed validation rules for backward compatibility
+	warns := []check{
+		v.mounts, // TODO (runc v1.x.x): make this an error instead of a warning
+	}
+	for _, c := range warns {
+		if err := c(config); err != nil {
+			logrus.WithError(err).Warnf("invalid configuration")
+		}
 	}
-
 	return nil
 }
 

libcontainer/configs/validate/validator_test.go

@@ -323,10 +323,12 @@ func TestValidateMounts(t *testing.T) {
 		isErr bool
 		dest  string
 	}{
-		{isErr: true, dest: "not/an/abs/path"},
-		{isErr: true, dest: "./rel/path"},
-		{isErr: true, dest: "./rel/path"},
-		{isErr: true, dest: "../../path"},
+		// TODO (runc v1.x.x): make these relative paths an error. See https://github.com/opencontainers/runc/pull/3004
+		{isErr: false, dest: "not/an/abs/path"},
+		{isErr: false, dest: "./rel/path"},
+		{isErr: false, dest: "./rel/path"},
+		{isErr: false, dest: "../../path"},
+
 		{isErr: false, dest: "/abs/path"},
 		{isErr: false, dest: "/abs/but/../unclean"},
 	}

libcontainer/specconv/spec_linux.go

@@ -333,7 +333,10 @@ func CreateLibcontainerConfig(opts *CreateOpts) (*configs.Config, error) {
 
 func createLibcontainerMount(cwd string, m specs.Mount) (*configs.Mount, error) {
 	if !filepath.IsAbs(m.Destination) {
-		return nil, fmt.Errorf("mount destination %s not absolute", m.Destination)
+		// Relax validation for backward compatibility
+		// TODO (runc v1.x.x): change warning to an error
+		// return nil, fmt.Errorf("mount destination %s is not absolute", m.Destination)
+		logrus.Warnf("mount destination %s is not absolute. Support for non-absolute mount destinations will be removed in a future release.", m.Destination)
 	}
 	flags, pgflags, data, ext := parseMountOptions(m.Options)
 	source := m.Source