Revert "libct/validator: Error out on non-abs paths"

This reverts commit 881e92a3fd and adjust
the code so the idmap validations are strict.

We now only throw a warning and the container is started just fine.

Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>

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"
 )
 
@@ -28,13 +29,22 @@ func Validate(config *configs.Config) error {
 		sysctl,
 		intelrdtCheck,
 		rootlessEUIDCheck,
-		mounts,
+		mountsStrict,
 	}
 	for _, c := range checks {
 		if err := c(config); err != nil {
 			return err
 		}
 	}
+	// Relaxed validation rules for backward compatibility
+	warns := []check{
+		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).Warn("invalid configuration")
+		}
+	}
 	return nil
 }
 
@@ -282,19 +292,19 @@ func checkIDMapMounts(config *configs.Config, m *configs.Mount) error {
 
 func mounts(config *configs.Config) error {
 	for _, m := range config.Mounts {
-		// We upgraded this to an error in runc 1.2. We might need to
-		// revert this change if some users haven't still moved to use
-		// abs paths, in that please move this check inside
-		// checkIDMapMounts() as we do want to ensure that for idmap
-		// mounts anyways.
 		if !filepath.IsAbs(m.Destination) {
 			return fmt.Errorf("invalid mount %+v: mount destination not absolute", m)
 		}
+	}
+	return nil
+}
+
+func mountsStrict(config *configs.Config) error {
+	for _, m := range config.Mounts {
 		if err := checkIDMapMounts(config, m); err != nil {
 			return fmt.Errorf("invalid mount %+v: %w", m, err)
 		}
 	}
-
 	return nil
 }
 

libcontainer/configs/validate/validator_test.go

@@ -360,10 +360,11 @@ 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"},
@@ -514,8 +515,7 @@ func TestValidateIDMapMounts(t *testing.T) {
 			},
 		},
 		{
-			name:  "idmap mounts without abs dest path",
-			isErr: true,
+			name: "idmap mounts without abs dest path",
 			config: &configs.Config{
 				UIDMappings: mapping,
 				GIDMappings: mapping,
@@ -530,7 +530,6 @@ func TestValidateIDMapMounts(t *testing.T) {
 				},
 			},
 		},
-
 		{
 			name: "simple idmap mount",
 			config: &configs.Config{
@@ -571,7 +570,7 @@ func TestValidateIDMapMounts(t *testing.T) {
 			config := tc.config
 			config.Rootfs = "/var"
 
-			err := mounts(config)
+			err := mountsStrict(config)
 			if tc.isErr && err == nil {
 				t.Error("expected error, got nil")
 			}