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scanner.go
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scanner.go
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package rego
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"io/fs"
"maps"
"strings"
"github.com/open-policy-agent/opa/ast"
"github.com/open-policy-agent/opa/rego"
"github.com/open-policy-agent/opa/storage"
"github.com/open-policy-agent/opa/util"
"github.com/aquasecurity/trivy/pkg/iac/framework"
"github.com/aquasecurity/trivy/pkg/iac/providers"
"github.com/aquasecurity/trivy/pkg/iac/rego/schemas"
"github.com/aquasecurity/trivy/pkg/iac/scan"
"github.com/aquasecurity/trivy/pkg/iac/scanners/options"
"github.com/aquasecurity/trivy/pkg/iac/types"
"github.com/aquasecurity/trivy/pkg/log"
)
var checkTypesWithSubtype = map[types.Source]struct{}{
types.SourceCloud: {},
types.SourceDefsec: {},
types.SourceKubernetes: {},
}
var supportedProviders = makeSupportedProviders()
func makeSupportedProviders() map[string]struct{} {
m := make(map[string]struct{})
for _, p := range providers.AllProviders() {
m[string(p)] = struct{}{}
}
m["kind"] = struct{}{} // kubernetes
return m
}
var _ options.ConfigurableScanner = (*Scanner)(nil)
type Scanner struct {
ruleNamespaces map[string]struct{}
policies map[string]*ast.Module
store storage.Store
runtimeValues *ast.Term
compiler *ast.Compiler
regoErrorLimit int
logger *log.Logger
traceWriter io.Writer
tracePerResult bool
retriever *MetadataRetriever
policyFS fs.FS
policyDirs []string
policyReaders []io.Reader
dataFS fs.FS
dataDirs []string
frameworks []framework.Framework
inputSchema any // unmarshalled into this from a json schema document
sourceType types.Source
includeDeprecatedChecks bool
includeEmbeddedPolicies bool
includeEmbeddedLibraries bool
embeddedLibs map[string]*ast.Module
embeddedChecks map[string]*ast.Module
customSchemas map[string][]byte
}
func (s *Scanner) SetIncludeDeprecatedChecks(b bool) {
s.includeDeprecatedChecks = b
}
func (s *Scanner) SetRegoOnly(bool) {}
func (s *Scanner) SetFrameworks(frameworks []framework.Framework) {
s.frameworks = frameworks
}
func (s *Scanner) trace(heading string, input any) {
if s.traceWriter == nil {
return
}
data, err := json.MarshalIndent(input, "", " ")
if err != nil {
return
}
_, _ = fmt.Fprintf(s.traceWriter, "REGO %[1]s:\n%s\nEND REGO %[1]s\n\n", heading, string(data))
}
type DynamicMetadata struct {
Warning bool
Filepath string
Message string
StartLine int
EndLine int
}
func NewScanner(source types.Source, opts ...options.ScannerOption) *Scanner {
LoadAndRegister()
schema, ok := schemas.SchemaMap[source]
if !ok {
schema = schemas.Anything
}
s := &Scanner{
regoErrorLimit: ast.CompileErrorLimitDefault,
sourceType: source,
ruleNamespaces: make(map[string]struct{}),
runtimeValues: addRuntimeValues(),
logger: log.WithPrefix("rego"),
customSchemas: make(map[string][]byte),
}
maps.Copy(s.ruleNamespaces, builtinNamespaces)
for _, opt := range opts {
opt(s)
}
if schema != schemas.None {
err := json.Unmarshal([]byte(schema), &s.inputSchema)
if err != nil {
panic(err)
}
}
return s
}
func (s *Scanner) runQuery(ctx context.Context, query string, input ast.Value, disableTracing bool) (rego.ResultSet, []string, error) {
trace := (s.traceWriter != nil || s.tracePerResult) && !disableTracing
regoOptions := []func(*rego.Rego){
rego.Query(query),
rego.Compiler(s.compiler),
rego.Store(s.store),
rego.Runtime(s.runtimeValues),
rego.Trace(trace),
}
if s.inputSchema != nil {
schemaSet := ast.NewSchemaSet()
schemaSet.Put(ast.MustParseRef("schema.input"), s.inputSchema)
regoOptions = append(regoOptions, rego.Schemas(schemaSet))
}
if input != nil {
regoOptions = append(regoOptions, rego.ParsedInput(input))
}
instance := rego.New(regoOptions...)
set, err := instance.Eval(ctx)
if err != nil {
return nil, nil, err
}
// we also build a slice of trace lines for per-result tracing - primarily for fanal/trivy
var traces []string
if trace {
if s.traceWriter != nil {
rego.PrintTrace(s.traceWriter, instance)
}
if s.tracePerResult {
traceBuffer := bytes.NewBuffer([]byte{})
rego.PrintTrace(traceBuffer, instance)
traces = strings.Split(traceBuffer.String(), "\n")
}
}
return set, traces, nil
}
type Input struct {
Path string `json:"path"`
FS fs.FS `json:"-"`
Contents any `json:"contents"`
}
func GetInputsContents(inputs []Input) []any {
results := make([]any, len(inputs))
for i, c := range inputs {
results[i] = c.Contents
}
return results
}
func (s *Scanner) ScanInput(ctx context.Context, inputs ...Input) (scan.Results, error) {
s.logger.Debug("Scanning inputs", "count", len(inputs))
var results scan.Results
for _, module := range s.policies {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
namespace := getModuleNamespace(module)
topLevel := strings.Split(namespace, ".")[0]
if _, ok := s.ruleNamespaces[topLevel]; !ok {
continue
}
staticMeta, err := s.retriever.RetrieveMetadata(ctx, module, GetInputsContents(inputs)...)
if err != nil {
s.logger.Error(
"Error occurred while retrieving metadata from check",
log.FilePath(module.Package.Location.File),
log.Err(err),
)
continue
}
if !s.includeDeprecatedChecks && staticMeta.Deprecated {
continue // skip deprecated checks
}
if isPolicyWithSubtype(s.sourceType) {
// skip if check isn't relevant to what is being scanned
if !isPolicyApplicable(staticMeta, inputs...) {
continue
}
}
if len(inputs) == 0 {
continue
}
usedRules := make(map[string]struct{})
// all rules
for _, rule := range module.Rules {
ruleName := rule.Head.Name.String()
if _, ok := usedRules[ruleName]; ok {
continue
}
usedRules[ruleName] = struct{}{}
if isEnforcedRule(ruleName) {
ruleResults, err := s.applyRule(ctx, namespace, ruleName, inputs, staticMeta.InputOptions.Combined)
if err != nil {
s.logger.Error(
"Error occurred while applying rule from check",
log.String("rule", ruleName),
log.FilePath(module.Package.Location.File),
log.Err(err),
)
continue
}
results = append(results, s.embellishResultsWithRuleMetadata(ruleResults, *staticMeta)...)
}
}
}
return results, nil
}
func isPolicyWithSubtype(sourceType types.Source) bool {
_, exists := checkTypesWithSubtype[sourceType]
return exists
}
func checkSubtype(ii map[string]any, provider string, subTypes []SubType) bool {
if len(subTypes) == 0 {
return true
}
for _, st := range subTypes {
switch services := ii[provider].(type) {
case map[string]any:
if st.Provider != provider {
continue
}
if _, exists := services[st.Service]; exists {
return true
}
case string: // k8s - logic can be improved
if strings.EqualFold(services, st.Group) ||
strings.EqualFold(services, st.Version) ||
strings.EqualFold(services, st.Kind) {
return true
}
}
}
return false
}
func isPolicyApplicable(staticMetadata *StaticMetadata, inputs ...Input) bool {
for _, input := range inputs {
if ii, ok := input.Contents.(map[string]any); ok {
for provider := range ii {
if _, exists := supportedProviders[provider]; !exists {
continue
}
if len(staticMetadata.InputOptions.Selectors) == 0 { // check always applies if no selectors
return true
}
// check metadata for subtype
for _, s := range staticMetadata.InputOptions.Selectors {
if checkSubtype(ii, provider, s.Subtypes) {
return true
}
}
}
}
}
return false
}
func parseRawInput(input any) (ast.Value, error) {
if err := util.RoundTrip(&input); err != nil {
return nil, err
}
return ast.InterfaceToValue(input)
}
func (s *Scanner) applyRule(ctx context.Context, namespace, rule string, inputs []Input, combined bool) (scan.Results, error) {
// handle combined evaluations if possible
if combined {
s.trace("INPUT", inputs)
return s.applyRuleCombined(ctx, namespace, rule, inputs)
}
var results scan.Results
qualified := fmt.Sprintf("data.%s.%s", namespace, rule)
for _, input := range inputs {
s.trace("INPUT", input)
parsedInput, err := parseRawInput(input.Contents)
if err != nil {
s.logger.Error("Error occurred while parsing input", log.Err(err))
continue
}
if ignored, err := s.isIgnored(ctx, namespace, rule, parsedInput); err != nil {
return nil, err
} else if ignored {
var result regoResult
result.FS = input.FS
result.Filepath = input.Path
result.Managed = true
results.AddIgnored(result)
continue
}
set, traces, err := s.runQuery(ctx, qualified, parsedInput, false)
if err != nil {
return nil, err
}
s.trace("RESULTSET", set)
ruleResults := s.convertResults(set, input, namespace, rule, traces)
if len(ruleResults) == 0 { // It passed because we didn't find anything wrong (NOT because it didn't exist)
var result regoResult
result.FS = input.FS
result.Filepath = input.Path
result.Managed = true
results.AddPassedRego(namespace, rule, traces, result)
continue
}
results = append(results, ruleResults...)
}
return results, nil
}
func (s *Scanner) applyRuleCombined(ctx context.Context, namespace, rule string, inputs []Input) (scan.Results, error) {
if len(inputs) == 0 {
return nil, nil
}
parsed, err := parseRawInput(inputs)
if err != nil {
return nil, fmt.Errorf("failed to parse input: %w", err)
}
var results scan.Results
if ignored, err := s.isIgnored(ctx, namespace, rule, parsed); err != nil {
return nil, err
} else if ignored {
for _, input := range inputs {
var result regoResult
result.FS = input.FS
result.Filepath = input.Path
result.Managed = true
results.AddIgnored(result)
}
return results, nil
}
qualified := fmt.Sprintf("data.%s.%s", namespace, rule)
set, traces, err := s.runQuery(ctx, qualified, parsed, false)
if err != nil {
return nil, err
}
return s.convertResults(set, inputs[0], namespace, rule, traces), nil
}
// severity is now set with metadata, so deny/warn/violation now behave the same way
func isEnforcedRule(name string) bool {
switch {
case name == "deny", strings.HasPrefix(name, "deny_"),
name == "warn", strings.HasPrefix(name, "warn_"),
name == "violation", strings.HasPrefix(name, "violation_"):
return true
}
return false
}