Files
act_runner/internal/app/run/runner.go
silverwind 5edc4ba550 Authenticate cache requests via ACTIONS_RUNTIME_TOKEN and scope by repo (#849)
Closes #848. Addresses [GHSA-82g9-637c-2fx2](https://github.com/go-gitea/gitea/security/advisories/GHSA-82g9-637c-2fx2) and the follow-up points raised by @ChristopherHX and @haroutp in that thread.

The change is breaking only for `cache.external_server` which uses auth via a pre-shared secret.

## How auth works now

1. **Runner starts** → opens the embedded cache server on `:port`. Loads / creates a 32-byte HMAC signing key in `<cache-dir>/.secret`.
2. **Runner receives a task** → calls `handler.RegisterJob(ACTIONS_RUNTIME_TOKEN, repository)` before the job runs, defers a revoker that removes the credential on completion. Registrations are reference-counted so a stray re-register cannot revoke a live job.
3. **Job container runs `actions/cache`** → the toolkit sends `Authorization: Bearer $ACTIONS_RUNTIME_TOKEN` on every management call (`reserve`, `upload`, `commit`, `find`, `clean`). The cache server's middleware looks the token up in the registered-jobs map: miss → 401; hit → the job's repository is injected into the request context.
4. **Repository scoping** — every cache entry is stamped with `Repo` on reserve; `find`, `upload`, `commit` all verify the caller's repo matches. A job in repo A cannot see or poison a cache entry owned by repo B, even when both reach the server over the same docker bridge. GC dedup also groups by `(Repo, Key, Version)` so one repo can't age out another.
5. **Archive downloads** — `@actions/cache` does not attach Authorization when downloading `archiveLocation`, so the `find` response is a short-lived HMAC-signed URL: `…/artifacts/:id?exp=<unix>&sig=<hmac>`, 10-minute TTL, signature binds `cacheID:exp`. Tampered, expired, or foreign-secret URLs get 401.
6. **Defence-in-depth** — `ACTIONS_RUNTIME_TOKEN` is added to `task.Secrets` so the runner's log masker scrubs it from step output.

## `cache.external_server` (standalone `act_runner cache-server`)

Operators set `cache.external_secret` to the same value on the runner config and the `act_runner cache-server` config. The `cache-server` then runs with bearer auth on the cache API and exposes a control-plane at `POST /_internal/{register,revoke}` (gated by the shared secret). The runner pre-registers each task's `ACTIONS_RUNTIME_TOKEN` with the remote server before the job runs and revokes it on completion. Same per-job auth + repo scoping as the embedded handler, just over the network.

`cache-server` refuses to start without `cache.external_secret`; runner config load also fails when `cache.external_server` is set without `cache.external_secret`.

## User-facing changes

- **One-time cache miss after upgrade.** Pre-existing entries in `bolt.db` have no `Repo` stamp and won't match any job — they'll be evicted by the normal GC. First job per cache key rebuilds its cache.
- **`cache.external_server` deployments must add `cache.external_secret`.** Breaking change for anyone running a standalone `act_runner cache-server`: set the same `cache.external_secret` in both the runner config and the cache-server config. Without it neither side starts.
- **No config changes required for the default setup.** Runners using the embedded cache server (the common case) keep working without any yaml edits; the auth mechanism is invisible to workflows.

---
This PR was written with the help of Claude Opus 4.7

---------

Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: Christopher Homberger <christopher.homberger@web.de>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/849
Reviewed-by: ChristopherHX <38043+christopherhx@noreply.gitea.com>
2026-04-27 23:59:20 +00:00

389 lines
13 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package run
import (
"bytes"
"context"
"encoding/json"
"fmt"
"maps"
"net/http"
"os"
"path/filepath"
"strings"
"sync"
"sync/atomic"
"time"
"gitea.com/gitea/act_runner/act/artifactcache"
"gitea.com/gitea/act_runner/act/common"
"gitea.com/gitea/act_runner/act/model"
"gitea.com/gitea/act_runner/act/runner"
"gitea.com/gitea/act_runner/internal/pkg/client"
"gitea.com/gitea/act_runner/internal/pkg/config"
"gitea.com/gitea/act_runner/internal/pkg/labels"
"gitea.com/gitea/act_runner/internal/pkg/metrics"
"gitea.com/gitea/act_runner/internal/pkg/report"
"gitea.com/gitea/act_runner/internal/pkg/ver"
runnerv1 "code.gitea.io/actions-proto-go/runner/v1"
"connectrpc.com/connect"
"github.com/docker/docker/api/types/container"
log "github.com/sirupsen/logrus"
)
// Runner runs the pipeline.
type Runner struct {
name string
cfg *config.Config
client client.Client
labels labels.Labels
envs map[string]string
cacheHandler *artifactcache.Handler
runningTasks sync.Map
runningCount atomic.Int64
}
func NewRunner(cfg *config.Config, reg *config.Registration, cli client.Client) *Runner {
ls := labels.Labels{}
for _, v := range reg.Labels {
if l, err := labels.Parse(v); err == nil {
ls = append(ls, l)
}
}
envs := make(map[string]string, len(cfg.Runner.Envs))
maps.Copy(envs, cfg.Runner.Envs)
var cacheHandler *artifactcache.Handler
if cfg.Cache.Enabled == nil || *cfg.Cache.Enabled {
if cfg.Cache.ExternalServer != "" {
envs["ACTIONS_CACHE_URL"] = cfg.Cache.ExternalServer
} else {
handler, err := artifactcache.StartHandler(
cfg.Cache.Dir,
cfg.Cache.Host,
cfg.Cache.Port,
"",
log.StandardLogger().WithField("module", "cache_request"),
)
if err != nil {
log.Errorf("cannot init cache server, it will be disabled: %v", err)
// go on
} else {
cacheHandler = handler
envs["ACTIONS_CACHE_URL"] = handler.ExternalURL() + "/"
}
}
}
// set artifact gitea api
artifactGiteaAPI := strings.TrimSuffix(cli.Address(), "/") + "/api/actions_pipeline/"
envs["ACTIONS_RUNTIME_URL"] = artifactGiteaAPI
envs["ACTIONS_RESULTS_URL"] = strings.TrimSuffix(cli.Address(), "/")
// Set specific environments to distinguish between Gitea and GitHub
envs["GITEA_ACTIONS"] = "true"
envs["GITEA_ACTIONS_RUNNER_VERSION"] = ver.Version()
return &Runner{
name: reg.Name,
cfg: cfg,
client: cli,
labels: ls,
envs: envs,
cacheHandler: cacheHandler,
}
}
func (r *Runner) Run(ctx context.Context, task *runnerv1.Task) error {
if _, ok := r.runningTasks.Load(task.Id); ok {
return fmt.Errorf("task %d is already running", task.Id)
}
r.runningTasks.Store(task.Id, struct{}{})
defer r.runningTasks.Delete(task.Id)
r.runningCount.Add(1)
start := time.Now()
ctx, cancel := context.WithTimeout(ctx, r.cfg.Runner.Timeout)
defer cancel()
reporter := report.NewReporter(ctx, cancel, r.client, task, r.cfg)
var runErr error
defer func() {
r.runningCount.Add(-1)
lastWords := ""
if runErr != nil {
lastWords = runErr.Error()
}
_ = reporter.Close(lastWords)
metrics.JobDuration.Observe(time.Since(start).Seconds())
metrics.JobsTotal.WithLabelValues(metrics.ResultToStatusLabel(reporter.Result())).Inc()
}()
reporter.RunDaemon()
runErr = r.run(ctx, task, reporter)
return nil
}
// getDefaultActionsURL
// when DEFAULT_ACTIONS_URL == "https://github.com" and GithubMirror is not blank,
// it should be set to GithubMirror first.
func (r *Runner) getDefaultActionsURL(task *runnerv1.Task) string {
giteaDefaultActionsURL := task.Context.Fields["gitea_default_actions_url"].GetStringValue()
if giteaDefaultActionsURL == "https://github.com" && r.cfg.Runner.GithubMirror != "" {
return r.cfg.Runner.GithubMirror
}
return giteaDefaultActionsURL
}
func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.Reporter) (err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("panic: %v", r)
}
}()
reporter.Logf("%s(version:%s) received task %v of job %v, be triggered by event: %s", r.name, ver.Version(), task.Id, task.Context.Fields["job"].GetStringValue(), task.Context.Fields["event_name"].GetStringValue())
workflow, jobID, err := generateWorkflow(task)
if err != nil {
return err
}
plan, err := model.CombineWorkflowPlanner(workflow).PlanJob(jobID)
if err != nil {
return err
}
job := workflow.GetJob(jobID)
reporter.ResetSteps(len(job.Steps))
taskContext := task.Context.Fields
log.Infof("task %v repo is %v %v %v", task.Id, taskContext["repository"].GetStringValue(),
r.getDefaultActionsURL(task),
r.client.Address())
preset := &model.GithubContext{
Event: taskContext["event"].GetStructValue().AsMap(),
RunID: taskContext["run_id"].GetStringValue(),
RunNumber: taskContext["run_number"].GetStringValue(),
RunAttempt: taskContext["run_attempt"].GetStringValue(),
Actor: taskContext["actor"].GetStringValue(),
Repository: taskContext["repository"].GetStringValue(),
EventName: taskContext["event_name"].GetStringValue(),
Sha: taskContext["sha"].GetStringValue(),
Ref: taskContext["ref"].GetStringValue(),
RefName: taskContext["ref_name"].GetStringValue(),
RefType: taskContext["ref_type"].GetStringValue(),
HeadRef: taskContext["head_ref"].GetStringValue(),
BaseRef: taskContext["base_ref"].GetStringValue(),
Token: taskContext["token"].GetStringValue(),
RepositoryOwner: taskContext["repository_owner"].GetStringValue(),
RetentionDays: taskContext["retention_days"].GetStringValue(),
}
if t := task.Secrets["GITEA_TOKEN"]; t != "" {
preset.Token = t
} else if t := task.Secrets["GITHUB_TOKEN"]; t != "" {
preset.Token = t
}
if actionsIDTokenRequestURL := taskContext["actions_id_token_request_url"].GetStringValue(); actionsIDTokenRequestURL != "" {
r.envs["ACTIONS_ID_TOKEN_REQUEST_URL"] = actionsIDTokenRequestURL
r.envs["ACTIONS_ID_TOKEN_REQUEST_TOKEN"] = taskContext["actions_id_token_request_token"].GetStringValue()
task.Secrets["ACTIONS_ID_TOKEN_REQUEST_TOKEN"] = r.envs["ACTIONS_ID_TOKEN_REQUEST_TOKEN"]
}
giteaRuntimeToken := taskContext["gitea_runtime_token"].GetStringValue()
if giteaRuntimeToken == "" {
// use task token to action api token for previous Gitea Server Versions
giteaRuntimeToken = preset.Token
}
r.envs["ACTIONS_RUNTIME_TOKEN"] = giteaRuntimeToken
// Mask the runtime token so it cannot be echoed in user step output; it is
// now also the cache server's bearer credential and leaking it would let
// any reader of the log impersonate this job against the cache.
if giteaRuntimeToken != "" {
task.Secrets["ACTIONS_RUNTIME_TOKEN"] = giteaRuntimeToken
}
// Register this job's runtime token with the local cache server so that
// cache requests from the job container can authenticate. The credential
// is removed when the task finishes, so a leaked token stops working as
// soon as the job ends rather than remaining valid for the runner's
// lifetime. Only applies to the embedded cache server; when the operator
// points the runner at an external cache via cfg.Cache.ExternalServer, it
// is that server's responsibility to authenticate requests.
defer r.registerCacheForTask(giteaRuntimeToken, preset.Repository, reporter)()
eventJSON, err := json.Marshal(preset.Event)
if err != nil {
return err
}
maxLifetime := 3 * time.Hour
if deadline, ok := ctx.Deadline(); ok {
maxLifetime = time.Until(deadline)
}
workdirParent := strings.TrimLeft(r.cfg.Container.WorkdirParent, "/")
if r.cfg.Container.BindWorkdir {
// Append the task ID to isolate concurrent jobs from the same repo.
workdirParent = fmt.Sprintf("%s/%d", workdirParent, task.Id)
}
workdir := filepath.FromSlash(fmt.Sprintf("/%s/%s", workdirParent, preset.Repository))
runnerConfig := &runner.Config{
// On Linux, Workdir will be like "/<parent_directory>/<owner>/<repo>"
// On Windows, Workdir will be like "\<parent_directory>\<owner>\<repo>"
Workdir: workdir,
BindWorkdir: r.cfg.Container.BindWorkdir,
ActionCacheDir: filepath.FromSlash(r.cfg.Host.WorkdirParent),
ReuseContainers: false,
ForcePull: r.cfg.Container.ForcePull,
ForceRebuild: r.cfg.Container.ForceRebuild,
LogOutput: true,
JSONLogger: false,
Env: r.envs,
Secrets: task.Secrets,
GitHubInstance: strings.TrimSuffix(r.client.Address(), "/"),
AutoRemove: true,
NoSkipCheckout: true,
PresetGitHubContext: preset,
EventJSON: string(eventJSON),
ContainerNamePrefix: fmt.Sprintf("GITEA-ACTIONS-TASK-%d", task.Id),
ContainerMaxLifetime: maxLifetime,
ContainerNetworkMode: container.NetworkMode(r.cfg.Container.Network),
ContainerOptions: r.cfg.Container.Options,
ContainerDaemonSocket: r.cfg.Container.DockerHost,
Privileged: r.cfg.Container.Privileged,
DefaultActionInstance: r.getDefaultActionsURL(task),
PlatformPicker: r.labels.PickPlatform,
Vars: task.Vars,
ValidVolumes: r.cfg.Container.ValidVolumes,
InsecureSkipTLS: r.cfg.Runner.Insecure,
}
rr, err := runner.New(runnerConfig)
if err != nil {
return err
}
executor := rr.NewPlanExecutor(plan)
reporter.Logf("workflow prepared")
// add logger recorders
ctx = common.WithLoggerHook(ctx, reporter)
if !log.IsLevelEnabled(log.DebugLevel) {
ctx = runner.WithJobLoggerFactory(ctx, NullLogger{})
}
execErr := executor(ctx)
reporter.SetOutputs(job.Outputs)
if r.cfg.Container.BindWorkdir {
// Remove the entire task-specific directory (e.g. /workspace/<task_id>).
taskDir := filepath.FromSlash("/" + workdirParent)
if err := os.RemoveAll(taskDir); err != nil {
log.Warnf("failed to clean up workspace %s: %v", taskDir, err)
}
}
return execErr
}
// registerCacheForTask tells the cache server to accept requests authenticated
// with the given runtime token for the duration of this task. Returns a
// function the caller must invoke (typically via defer) to revoke the
// credential when the task finishes.
//
// Three modes:
// - Embedded handler: register in-process via RegisterJob.
// - external_server + external_secret: POST to the remote server's
// /_internal/register, defer a POST to /_internal/revoke. This is what
// enables full per-job auth and repo scoping over the network.
// - external_server alone (no secret): no-op revoker. The remote server is
// in legacy openMode and ignores the runtime token; trust is at the
// network layer.
//
// Safe with an empty token (older Gitea did not issue one).
func (r *Runner) registerCacheForTask(token, repo string, reporter *report.Reporter) func() {
if token == "" {
return func() {}
}
if r.cacheHandler != nil {
return r.cacheHandler.RegisterJob(token, repo)
}
if r.cfg.Cache.ExternalServer != "" && r.cfg.Cache.ExternalSecret != "" {
return r.registerExternalCacheJob(token, repo, reporter)
}
return func() {}
}
// registerExternalCacheJob POSTs to the remote cache-server's control-plane.
// Failures are logged but not fatal: if registration fails, the cache will
// 401 the job's requests — better than failing the whole task for a cache
// outage. The warning is mirrored to the job log so users can see why their
// cache calls 401, instead of having to read the runner daemon's stderr.
func (r *Runner) registerExternalCacheJob(token, repo string, reporter *report.Reporter) func() {
base := strings.TrimRight(r.cfg.Cache.ExternalServer, "/")
if err := postInternalCache(base+"/_internal/register", r.cfg.Cache.ExternalSecret,
map[string]string{"token": token, "repo": repo}); err != nil {
log.Warnf("cache external_server register failed (%s): %v", base, err)
if reporter != nil {
reporter.Logf("::warning::cache external_server register failed (%s): %v — cache requests from this job will be unauthenticated and likely return 401", base, err)
}
}
return func() {
if err := postInternalCache(base+"/_internal/revoke", r.cfg.Cache.ExternalSecret,
map[string]string{"token": token}); err != nil {
log.Warnf("cache external_server revoke failed (%s): %v", base, err)
if reporter != nil {
reporter.Logf("::warning::cache external_server revoke failed (%s): %v", base, err)
}
}
}
}
func postInternalCache(url, secret string, body map[string]string) error {
buf, err := json.Marshal(body)
if err != nil {
return err
}
req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(buf))
if err != nil {
return err
}
req.Header.Set("Authorization", "Bearer "+secret)
req.Header.Set("Content-Type", "application/json")
client := &http.Client{Timeout: 5 * time.Second}
resp, err := client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode/100 != 2 {
return fmt.Errorf("status %d", resp.StatusCode)
}
return nil
}
func (r *Runner) RunningCount() int64 {
return r.runningCount.Load()
}
func (r *Runner) Declare(ctx context.Context, labels []string) (*connect.Response[runnerv1.DeclareResponse], error) {
return r.client.Declare(ctx, connect.NewRequest(&runnerv1.DeclareRequest{
Version: ver.Version(),
Labels: labels,
}))
}