Merge pull request #27036 from sttts/sttts-secure-seccomp-path

Automatic merge from submit-queue

Filter seccomp profile path from malicious .. and /

Without this patch with `localhost/<some-releative-path>` as seccomp profile one can load any file on the host, e.g. `localhost/../../../../dev/mem` which is not healthy for the kubelet.

/cc @jfrazelle 

Unit tests depend on https://github.com/kubernetes/kubernetes/pull/26710.

pkg/api/validation/validation.go

@@ -122,6 +122,8 @@ func ValidatePodSpecificAnnotations(annotations map[string]string, fldPath *fiel
 		}
 	}
 
+	allErrs = append(allErrs, ValidateSeccompPodAnnotations(annotations, fldPath)...)
+
 	return allErrs
 }
 
@@ -1846,6 +1848,33 @@ func ValidateTolerationsInPodAnnotations(annotations map[string]string, fldPath
 	return allErrs
 }
 
+func validateSeccompProfile(p string, fldPath *field.Path) field.ErrorList {
+	if p == "docker/default" {
+		return nil
+	}
+	if p == "unconfined" {
+		return nil
+	}
+	if strings.HasPrefix(p, "localhost/") {
+		return validateSubPath(strings.TrimPrefix(p, "localhost/"), fldPath)
+	}
+	return field.ErrorList{field.Invalid(fldPath, p, "must be a valid seccomp profile")}
+}
+
+func ValidateSeccompPodAnnotations(annotations map[string]string, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if p, exists := annotations[api.SeccompPodAnnotationKey]; exists {
+		allErrs = append(allErrs, validateSeccompProfile(p, fldPath.Child(api.SeccompPodAnnotationKey))...)
+	}
+	for k, p := range annotations {
+		if strings.HasPrefix(k, api.SeccompContainerAnnotationKeyPrefix) {
+			allErrs = append(allErrs, validateSeccompProfile(p, fldPath.Child(k))...)
+		}
+	}
+
+	return allErrs
+}
+
 // ValidatePodSecurityContext test that the specified PodSecurityContext has valid data.
 func ValidatePodSecurityContext(securityContext *api.PodSecurityContext, spec *api.PodSpec, specPath, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}