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feat: whitelist for allowed env and paths for lua
Signed-off-by: Rudrakh Panigrahi <rudrakh97@gmail.com>
1 parent 6578a6d commit 1a9750a

13 files changed

Lines changed: 692 additions & 380 deletions

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‎api/v1alpha1/envoyproxy_types.go‎

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@@ -189,6 +189,20 @@ type EnvoyProxySpec struct {
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// +optional
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LuaValidation *LuaValidation `json:"luaValidation,omitempty"`
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// LuaStrictValidation defines the filesystem paths and environment variables that Lua
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// scripts from EnvoyExtensionPolicy resources are permitted to access during Strict
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// validation in the gateway controller.
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//
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// The allowlist is fail-closed: when unset or empty, Lua scripts are denied access to ALL
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// filesystem paths and environment variables during validation. Only entries that match the
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// allowlist are permitted.
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//
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// This field only takes effect when LuaValidation is Strict (the default). It has no effect
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// for the InsecureSyntax or Disabled validation modes, which do not execute the security sandbox.
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//
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// +optional
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LuaStrictValidation *LuaStrictValidation `json:"luaStrictValidation,omitempty"`
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// DynamicModules defines the set of dynamic modules that are allowed to be
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// used by EnvoyExtensionPolicy resources and dynamic module load balancer
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// policies. Each entry registers a module by a logical name and specifies
@@ -250,6 +264,39 @@ const (
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LuaValidationDisabled LuaValidation = "Disabled"
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)
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// LuaStrictValidation defines the configuration that Strict Lua validation runs with.
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//
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// This configuration only applies to the Strict validation mode; it has no effect on the
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// InsecureSyntax and Disabled modes.
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type LuaStrictValidation struct {
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// AllowedPaths is the list of filesystem path prefixes that Lua scripts are permitted to
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// access during validation (via io.open, io.input, io.output, io.lines, os.remove, os.rename).
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// A path is allowed when it equals an entry or is contained within an entry's subtree
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// (e.g. "/tmp" allows "/tmp/file.txt"). Paths are normalized (separators collapsed, made
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// absolute) before matching, and any "." or ".." traversal segment is always rejected.
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// When empty, all filesystem access is denied. Blank or whitespace-only entries are rejected,
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// as they would otherwise match every path and disable the sandbox.
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//
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// +kubebuilder:validation:MaxItems=64
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// +kubebuilder:validation:items:MinLength=1
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// +kubebuilder:validation:items:MaxLength=4096
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// +kubebuilder:validation:XValidation:rule="self.all(p, p.trim() != '')",message="allowedPaths entries must not be blank or whitespace-only"
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// +optional
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AllowedPaths []string `json:"allowedPaths,omitempty"`
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// AllowedEnvVars is the list of environment variable names that Lua scripts are permitted to
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// access during validation (via os.getenv, os.setenv). Matching is exact and case-sensitive.
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// When empty, access to all environment variables is denied. Blank or whitespace-only entries
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// are rejected.
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//
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// +kubebuilder:validation:MaxItems=64
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// +kubebuilder:validation:items:MinLength=1
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// +kubebuilder:validation:items:MaxLength=256
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// +kubebuilder:validation:XValidation:rule="self.all(e, e.trim() != '')",message="allowedEnvVars entries must not be blank or whitespace-only"
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// +optional
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AllowedEnvVars []string `json:"allowedEnvVars,omitempty"`
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}
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// RoutingType defines the type of routing of this Envoy proxy.
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type RoutingType string
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‎api/v1alpha1/zz_generated.deepcopy.go‎

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‎charts/gateway-crds-helm/templates/generated/gateway.envoyproxy.io_envoyproxies.yaml‎

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@@ -767,6 +767,53 @@ spec:
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and the log level is the value. If unspecified, defaults to "default: warn".
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type: object
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type: object
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luaStrictValidation:
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description: |-
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LuaStrictValidation defines the filesystem paths and environment variables that Lua
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scripts from EnvoyExtensionPolicy resources are permitted to access during Strict
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validation in the gateway controller.
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The allowlist is fail-closed: when unset or empty, Lua scripts are denied access to ALL
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filesystem paths and environment variables during validation. Only entries that match the
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allowlist are permitted.
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This field only takes effect when LuaValidation is Strict (the default). It has no effect
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for the InsecureSyntax or Disabled validation modes, which do not execute the security sandbox.
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properties:
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allowedEnvVars:
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description: |-
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AllowedEnvVars is the list of environment variable names that Lua scripts are permitted to
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access during validation (via os.getenv, os.setenv). Matching is exact and case-sensitive.
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When empty, access to all environment variables is denied. Blank or whitespace-only entries
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are rejected.
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items:
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maxLength: 256
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minLength: 1
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type: string
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maxItems: 64
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type: array
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x-kubernetes-validations:
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- message: allowedEnvVars entries must not be blank or whitespace-only
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rule: self.all(e, e.trim() != '')
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allowedPaths:
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description: |-
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AllowedPaths is the list of filesystem path prefixes that Lua scripts are permitted to
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access during validation (via io.open, io.input, io.output, io.lines, os.remove, os.rename).
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A path is allowed when it equals an entry or is contained within an entry's subtree
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(e.g. "/tmp" allows "/tmp/file.txt"). Paths are normalized (separators collapsed, made
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absolute) before matching, and any "." or ".." traversal segment is always rejected.
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When empty, all filesystem access is denied. Blank or whitespace-only entries are rejected,
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as they would otherwise match every path and disable the sandbox.
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items:
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maxLength: 4096
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minLength: 1
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type: string
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maxItems: 64
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type: array
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x-kubernetes-validations:
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- message: allowedPaths entries must not be blank or whitespace-only
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rule: self.all(p, p.trim() != '')
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type: object
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luaValidation:
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description: |-
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LuaValidation determines strictness of the Lua script validation for Lua EnvoyExtensionPolicies

‎charts/gateway-helm/charts/crds/crds/generated/gateway.envoyproxy.io_envoyproxies.yaml‎

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@@ -766,6 +766,53 @@ spec:
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and the log level is the value. If unspecified, defaults to "default: warn".
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type: object
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type: object
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luaStrictValidation:
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description: |-
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LuaStrictValidation defines the filesystem paths and environment variables that Lua
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scripts from EnvoyExtensionPolicy resources are permitted to access during Strict
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validation in the gateway controller.
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The allowlist is fail-closed: when unset or empty, Lua scripts are denied access to ALL
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filesystem paths and environment variables during validation. Only entries that match the
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allowlist are permitted.
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This field only takes effect when LuaValidation is Strict (the default). It has no effect
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for the InsecureSyntax or Disabled validation modes, which do not execute the security sandbox.
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properties:
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allowedEnvVars:
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description: |-
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AllowedEnvVars is the list of environment variable names that Lua scripts are permitted to
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access during validation (via os.getenv, os.setenv). Matching is exact and case-sensitive.
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When empty, access to all environment variables is denied. Blank or whitespace-only entries
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are rejected.
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items:
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maxLength: 256
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minLength: 1
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type: string
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maxItems: 64
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type: array
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x-kubernetes-validations:
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- message: allowedEnvVars entries must not be blank or whitespace-only
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rule: self.all(e, e.trim() != '')
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allowedPaths:
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description: |-
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AllowedPaths is the list of filesystem path prefixes that Lua scripts are permitted to
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access during validation (via io.open, io.input, io.output, io.lines, os.remove, os.rename).
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A path is allowed when it equals an entry or is contained within an entry's subtree
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(e.g. "/tmp" allows "/tmp/file.txt"). Paths are normalized (separators collapsed, made
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absolute) before matching, and any "." or ".." traversal segment is always rejected.
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When empty, all filesystem access is denied. Blank or whitespace-only entries are rejected,
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as they would otherwise match every path and disable the sandbox.
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items:
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maxLength: 4096
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minLength: 1
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type: string
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maxItems: 64
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type: array
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x-kubernetes-validations:
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- message: allowedPaths entries must not be blank or whitespace-only
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rule: self.all(p, p.trim() != '')
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type: object
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luaValidation:
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description: |-
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LuaValidation determines strictness of the Lua script validation for Lua EnvoyExtensionPolicies

‎internal/gatewayapi/luavalidator/lua_validator.go‎

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Original file line numberDiff line numberDiff line change
@@ -90,6 +90,59 @@ func (l *LuaValidator) getLuaValidation() egv1a1.LuaValidation {
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return egv1a1.LuaValidationStrict
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}
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// allowlistData generates the Lua source consumed by security.lua: the path allowlist as a list and
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// the env var allowlist as a map (name -> true). The allowlist is fail-closed; an unconfigured
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// EnvoyProxy yields empty tables, denying all access.
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func (l *LuaValidator) allowlistData() string {
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var paths, envVars []string
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if l.envoyProxy != nil && l.envoyProxy.Spec.LuaStrictValidation != nil {
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paths = l.envoyProxy.Spec.LuaStrictValidation.AllowedPaths
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envVars = l.envoyProxy.Spec.LuaStrictValidation.AllowedEnvVars
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}
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var b strings.Builder
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b.WriteString("__lua_allowed_paths = {")
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for i, p := range paths {
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if i > 0 {
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b.WriteString(", ")
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}
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b.WriteString(luaStringLiteral(p))
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}
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b.WriteString("}\n")
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b.WriteString("__lua_allowed_env_vars = {")
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for i, e := range envVars {
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if i > 0 {
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b.WriteString(", ")
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}
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// Spaces around the key are required: "[[[..." would lex as a long-string opener.
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b.WriteString("[ ")
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b.WriteString(luaStringLiteral(e))
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b.WriteString(" ] = true")
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}
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b.WriteString("}\n")
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return b.String()
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}
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// luaStringLiteral encodes s as a Lua long-bracket literal ([==[...]==]) with an equals level that
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// avoids any closing delimiter in s. Long brackets don't interpret escapes, so spec values are
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// passed verbatim as data and cannot inject Lua.
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func luaStringLiteral(s string) string {
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level := 0
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for strings.Contains(s, "]"+strings.Repeat("=", level)+"]") {
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level++
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}
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eq := strings.Repeat("=", level)
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// Lua strips a leading newline after the opening bracket; re-add it to preserve such values.
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prefix := ""
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if strings.HasPrefix(s, "\n") {
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prefix = "\n"
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}
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return "[" + eq + "[" + prefix + s + "]" + eq + "]"
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}
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// newLuaState creates a new Lua state with global settings and resource limits applied
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// Returns the Lua state and a cancel function that must be called when done
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func (l *LuaValidator) newLuaState() (*lua.LState, context.CancelFunc) {
@@ -123,6 +176,8 @@ func (l *LuaValidator) runLua(code string) error {
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// Execute mocks first (trusted code, needs setmetatable, defines StreamHandle, etc.)
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_ = L.DoString(mockData)
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// Inject the allowlists before security.lua, which reads and then clears them.
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_ = L.DoString(l.allowlistData())
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// Execute Lua security wrappers (trusted code) to protect the gateway controller
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// See security advisory: https://github.com/envoyproxy/gateway/security/advisories/GHSA-xrwg-mqj6-6m22
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_ = L.DoString(securityData)

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