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馃悰 Don't look for secrets in pull_request #1864

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merged 5 commits into from Apr 27, 2022
Merged

馃悰 Don't look for secrets in pull_request #1864

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1f08569
Remove pull_request
laurentsimon Apr 25, 2022
3f49d4f
updates
laurentsimon Apr 25, 2022
753370a
updates
laurentsimon Apr 26, 2022
a912c89
linter and e2e
laurentsimon Apr 26, 2022
3bab511
Merge branch 'main' into feat/bugdwsecrets
laurentsimon Apr 26, 2022
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11 changes: 2 additions & 9 deletions checker/raw_result.go
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Expand Up @@ -286,9 +286,8 @@ type CIIBestPracticesData struct {
// DangerousWorkflowData contains raw results
// for dangerous workflow check.
type DangerousWorkflowData struct {
ScriptInjections []ScriptInjection
SecretInPullRequests []EncryptedSecret
UntrustedCheckouts []UntrustedCheckout
ScriptInjections []ScriptInjection
UntrustedCheckouts []UntrustedCheckout
// TODO: other
}

Expand All @@ -304,12 +303,6 @@ type ScriptInjection struct {
File File
}

// EncryptedSecret represents an encrypted secret.
type EncryptedSecret struct {
Job *WorkflowJob
File File
}

// WorkflowJob reprresents a workflow job.
type WorkflowJob struct {
Name *string
Expand Down
14 changes: 1 addition & 13 deletions checks/evaluation/dangerous_workflow.go
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Expand Up @@ -52,20 +52,8 @@ func DangerousWorkflow(name string, dl checker.DetailLogger,
})
}

// Secrets in pull requests.
for _, e := range r.SecretInPullRequests {
dl.Warn(&checker.LogMessage{
Path: e.File.Path,
Type: e.File.Type,
Offset: e.File.Offset,
Text: fmt.Sprintf("secret accessible to pull requests '%v'", e.File.Snippet),
Snippet: e.File.Snippet,
})
}

if len(r.ScriptInjections) > 0 ||
len(r.UntrustedCheckouts) > 0 ||
len(r.SecretInPullRequests) > 0 {
len(r.UntrustedCheckouts) > 0 {
return createResult(name, checker.MinResultScore)
}
return createResult(name, checker.MaxResultScore)
Expand Down
256 changes: 0 additions & 256 deletions checks/raw/dangerous_workflow.go
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Expand Up @@ -60,7 +60,6 @@ type triggerName string
var (
triggerPullRequestTarget = triggerName("pull_request_target")
triggerWorkflowRun = triggerName("workflow_run")
triggerPullRequest = triggerName("pull_request")
checkoutUntrustedPullRequestRef = "github.event.pull_request"
checkoutUntrustedWorkflowRunRef = "github.event.workflow_run"
)
Expand Down Expand Up @@ -117,55 +116,10 @@ var validateGitHubActionWorkflowPatterns fileparser.DoWhileTrueOnFileContent = f
return false, err
}

// 3. Check for secrets used in workflows triggered by pull requests.
if err := validateSecretsInPullRequests(workflow, path, pdata); err != nil {
return false, err
}

// TODO: Check other dangerous patterns.
return true, nil
}

func validateSecretsInPullRequests(workflow *actionlint.Workflow, path string,
pdata *checker.DangerousWorkflowData,
) error {
triggers := make(map[triggerName]bool)

// We need pull request trigger.
usesPullRequest := usesEventTrigger(workflow, triggerPullRequest)
usesPullRequestTarget := usesEventTrigger(workflow, triggerPullRequestTarget)
usesWorkflowRun := usesEventTrigger(workflow, triggerWorkflowRun)

if !usesPullRequest && !usesPullRequestTarget && !usesWorkflowRun {
return nil
}

// Record the triggers.
if usesPullRequest {
triggers[triggerPullRequest] = usesPullRequest
}
if usesPullRequestTarget {
triggers[triggerPullRequestTarget] = usesPullRequestTarget
}
if usesWorkflowRun {
triggers[triggerWorkflowRun] = usesWorkflowRun
}

// Secrets used in env at the top of the wokflow.
if err := checkWorkflowSecretInEnv(workflow, triggers, path, pdata); err != nil {
return err
}

// Secrets used on jobs.
for _, job := range workflow.Jobs {
if err := checkJobForUsedSecrets(job, triggers, path, pdata); err != nil {
return err
}
}

return nil
}

func validateUntrustedCodeCheckout(workflow *actionlint.Workflow, path string,
pdata *checker.DangerousWorkflowData,
) error {
Expand Down Expand Up @@ -193,112 +147,6 @@ func usesEventTrigger(workflow *actionlint.Workflow, name triggerName) bool {
return false
}

func jobUsesEnvironment(job *actionlint.Job) bool {
if job.Environment == nil {
return false
}

return job.Environment.Name != nil &&
job.Environment.Name.Value != ""
}

func checkJobForUsedSecrets(job *actionlint.Job, triggers map[triggerName]bool,
path string, pdata *checker.DangerousWorkflowData,
) error {
if job == nil {
return nil
}

// If the job has an environment, assume it's an env secret gated by
// some approval and don't alert.
if !jobUsesCodeCheckoutAndNoEnvironment(job, triggers) {
return nil
}

// https://docs.github.com/en/actions/security-guides/encrypted-secrets#naming-your-secrets
for _, step := range job.Steps {
if step == nil {
continue
}

if err := checkSecretInActionArgs(step, job, path, pdata); err != nil {
return err
}

if err := checkSecretInRun(step, job, path, pdata); err != nil {
return err
}

if err := checkSecretInEnv(step.Env, job, path, pdata); err != nil {
return err
}
}
return nil
}

func workflowUsesCodeCheckoutAndNoEnvironment(workflow *actionlint.Workflow,
triggers map[triggerName]bool,
) bool {
if workflow == nil {
return false
}

for _, job := range workflow.Jobs {
if jobUsesCodeCheckoutAndNoEnvironment(job, triggers) {
return true
}
}
return false
}

func jobUsesCodeCheckoutAndNoEnvironment(job *actionlint.Job, triggers map[triggerName]bool,
) bool {
if job == nil {
return false
}
_, usesPullRequest := triggers[triggerPullRequest]
_, usesPullRequestTarget := triggers[triggerPullRequestTarget]
_, usesWorkflowRun := triggers[triggerWorkflowRun]

chk, ref := jobUsesCodeCheckout(job)
if !jobUsesEnvironment(job) {
if (chk && usesPullRequest) ||
(chk && usesPullRequestTarget && strings.Contains(ref, checkoutUntrustedPullRequestRef)) ||
(chk && usesWorkflowRun && strings.Contains(ref, checkoutUntrustedWorkflowRunRef)) {
return true
}
}

return false
}

func jobUsesCodeCheckout(job *actionlint.Job) (bool, string) {
if job == nil {
return false, ""
}

hasCheckout := false
for _, step := range job.Steps {
if step == nil || step.Exec == nil {
continue
}
// Check for a step that uses actions/checkout
e, ok := step.Exec.(*actionlint.ExecAction)
if !ok || e.Uses == nil {
continue
}
if strings.Contains(e.Uses.Value, "actions/checkout") {
hasCheckout = true
ref, ok := e.Inputs["ref"]
if !ok || ref.Value == nil {
continue
}
return true, ref.Value.Value
}
}
return hasCheckout, ""
}

func createJob(job *actionlint.Job) *checker.WorkflowJob {
if job == nil {
return nil
Expand Down Expand Up @@ -383,110 +231,6 @@ func validateScriptInjection(workflow *actionlint.Workflow, path string,
return nil
}

func checkWorkflowSecretInEnv(workflow *actionlint.Workflow, triggers map[triggerName]bool,
path string, pdata *checker.DangerousWorkflowData,
) error {
// We need code checkout and not environment rule protection.
if !workflowUsesCodeCheckoutAndNoEnvironment(workflow, triggers) {
return nil
}

return checkSecretInEnv(workflow.Env, nil, path, pdata)
}

func checkSecretInEnv(env *actionlint.Env, job *actionlint.Job, path string,
pdata *checker.DangerousWorkflowData,
) error {
if env == nil {
return nil
}

for _, v := range env.Vars {
if err := checkSecretInScript(v.Value.Value, v.Value.Pos, job, path, pdata); err != nil {
return err
}
}
return nil
}

func checkSecretInRun(step *actionlint.Step, job *actionlint.Job, path string,
pdata *checker.DangerousWorkflowData,
) error {
if step == nil || step.Exec == nil {
return nil
}

run, ok := step.Exec.(*actionlint.ExecRun)
if ok && run.Run != nil {
if err := checkSecretInScript(run.Run.Value, run.Run.Pos, job, path, pdata); err != nil {
return err
}
}
return nil
}

func checkSecretInActionArgs(step *actionlint.Step, job *actionlint.Job, path string,
pdata *checker.DangerousWorkflowData,
) error {
if step == nil || step.Exec == nil {
return nil
}

e, ok := step.Exec.(*actionlint.ExecAction)
if ok && e.Uses != nil {
// Check for reference. If not defined for a pull_request_target event, this defaults to
// the base branch of the pull request.
for _, v := range e.Inputs {
if v.Value != nil {
if err := checkSecretInScript(v.Value.Value, v.Value.Pos, job, path, pdata); err != nil {
return err
}
}
}
}
return nil
}

func checkSecretInScript(script string, pos *actionlint.Pos,
job *actionlint.Job, path string,
pdata *checker.DangerousWorkflowData,
) error {
for {
s := strings.Index(script, "${{")
if s == -1 {
break
}

e := strings.Index(script[s:], "}}")
if e == -1 {
return sce.WithMessage(sce.ErrScorecardInternal, errInvalidGitHubWorkflow.Error())
}

// Note: The default GitHub token is allowed, as it has
// only read permission for `pull_request`.
// For `pull_request_event`, we use other signals such as
// whether checkout action is used.
variable := strings.Trim(script[s:s+e+2], " ")
if !strings.Contains(variable, "secrets.GITHUB_TOKEN") &&
strings.Contains(variable, "secrets.") {
line := fileparser.GetLineNumber(pos)
pdata.SecretInPullRequests = append(pdata.SecretInPullRequests,
checker.EncryptedSecret{
File: checker.File{
Path: path,
Type: checker.FileTypeSource,
Offset: line,
Snippet: variable,
},
Job: createJob(job),
},
)
}
script = script[s+e:]
}
return nil
}

func checkVariablesInScript(script string, pos *actionlint.Pos,
job *actionlint.Job, path string,
pdata *checker.DangerousWorkflowData,
Expand Down