Fix host cleanup, volume allowlist, cache upload, and action host edge cases (#970)

## Summary
- prevent host-mode execution from deleting caller-owned workdirs
- harden `valid_volumes` checks against `..` and symlink escapes
- return immediately after artifact cache upload write failures
- default implicit remote action clone hosts to `GitHubInstance`/`github.com`

Authored with assistance from OpenAI Codex GPT-5.

---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/970
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>

act/container/docker_run.go

@@ -17,6 +17,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -968,22 +969,7 @@ func (cr *containerReference) sanitizeConfig(ctx context.Context, config *contai
 	logger := common.Logger(ctx)
 
 	if len(cr.input.ValidVolumes) > 0 {
-		globs := make([]glob.Glob, 0, len(cr.input.ValidVolumes))
-		for _, v := range cr.input.ValidVolumes {
-			if g, err := glob.Compile(v); err != nil {
-				logger.Errorf("create glob from %s error: %v", v, err)
-			} else {
-				globs = append(globs, g)
-			}
-		}
-		isValid := func(v string) bool {
-			for _, g := range globs {
-				if g.Match(v) {
-					return true
-				}
-			}
-			return false
-		}
+		matcher := newValidVolumeMatcher(ctx, cr.input.ValidVolumes)
 		// sanitize binds
 		sanitizedBinds := make([]string, 0, len(hostConfig.Binds))
 		for _, bind := range hostConfig.Binds {
@@ -997,7 +983,7 @@ func (cr *containerReference) sanitizeConfig(ctx context.Context, config *contai
 				sanitizedBinds = append(sanitizedBinds, bind)
 				continue
 			}
-			if isValid(parsed.Source) {
+			if matcher.isValid(parsed.Source, mount.Type(parsed.Type)) {
 				sanitizedBinds = append(sanitizedBinds, bind)
 			} else {
 				logger.Warnf("[%s] is not a valid volume, will be ignored", parsed.Source)
@@ -1007,7 +993,7 @@ func (cr *containerReference) sanitizeConfig(ctx context.Context, config *contai
 		// sanitize mounts
 		sanitizedMounts := make([]mount.Mount, 0, len(hostConfig.Mounts))
 		for _, mt := range hostConfig.Mounts {
-			if isValid(mt.Source) {
+			if matcher.isValid(mt.Source, mt.Type) {
 				sanitizedMounts = append(sanitizedMounts, mt)
 			} else {
 				logger.Warnf("[%s] is not a valid volume, will be ignored", mt.Source)
@@ -1021,3 +1007,129 @@ func (cr *containerReference) sanitizeConfig(ctx context.Context, config *contai
 
 	return config, hostConfig
 }
+
+type validVolumeMatcher struct {
+	allowAll bool
+	named    []glob.Glob
+	host     []glob.Glob
+}
+
+func newValidVolumeMatcher(ctx context.Context, validVolumes []string) validVolumeMatcher {
+	logger := common.Logger(ctx)
+	ret := validVolumeMatcher{
+		named: make([]glob.Glob, 0, len(validVolumes)),
+		host:  make([]glob.Glob, 0, len(validVolumes)),
+	}
+
+	for _, v := range validVolumes {
+		if v == "**" {
+			ret.allowAll = true
+			continue
+		}
+		if !isHostVolumePattern(v) {
+			if g, err := glob.Compile(v); err != nil {
+				logger.Errorf("create glob from %s error: %v", v, err)
+			} else {
+				ret.named = append(ret.named, g)
+			}
+			continue
+		}
+		normalized, err := normalizeHostVolumePath(v)
+		if err != nil {
+			logger.Errorf("normalize volume pattern %s error: %v", v, err)
+			continue
+		}
+		if g, err := glob.Compile(normalized); err != nil {
+			logger.Errorf("create glob from %s error: %v", normalized, err)
+		} else {
+			ret.host = append(ret.host, g)
+		}
+	}
+
+	return ret
+}
+
+func (m validVolumeMatcher) isValid(source string, sourceType mount.Type) bool {
+	if m.allowAll {
+		return true
+	}
+	if isHostVolumeSource(source, sourceType) {
+		normalized, err := normalizeHostVolumePath(source)
+		if err != nil {
+			return false
+		}
+		for _, g := range m.host {
+			if g.Match(normalized) {
+				return true
+			}
+		}
+		return false
+	}
+	for _, g := range m.named {
+		if g.Match(source) {
+			return true
+		}
+	}
+	return false
+}
+
+func isHostVolumePattern(pattern string) bool {
+	return filepath.IsAbs(pattern) ||
+		strings.HasPrefix(pattern, "."+string(filepath.Separator)) ||
+		strings.HasPrefix(pattern, ".."+string(filepath.Separator)) ||
+		strings.Contains(pattern, "/") ||
+		strings.Contains(pattern, `\`)
+}
+
+func isHostVolumeSource(source string, sourceType mount.Type) bool {
+	if sourceType == mount.TypeBind {
+		return true
+	}
+	if sourceType == mount.TypeVolume {
+		return false
+	}
+	return isHostVolumePattern(source)
+}
+
+func normalizeHostVolumePath(path string) (string, error) {
+	abs, err := filepath.Abs(path)
+	if err != nil {
+		return "", err
+	}
+	return evalSymlinksExistingPrefix(abs)
+}
+
+func evalSymlinksExistingPrefix(path string) (string, error) {
+	resolved, err := filepath.EvalSymlinks(path)
+	if err == nil {
+		return filepath.Clean(resolved), nil
+	}
+	if !errors.Is(err, os.ErrNotExist) {
+		return "", err
+	}
+
+	current := path
+	var missing []string
+	for {
+		_, err := os.Lstat(current)
+		if err == nil {
+			resolved, err := filepath.EvalSymlinks(current)
+			if err != nil {
+				return "", err
+			}
+			for _, name := range slices.Backward(missing) {
+				resolved = filepath.Join(resolved, name)
+			}
+			return filepath.Clean(resolved), nil
+		}
+		if !errors.Is(err, os.ErrNotExist) {
+			return "", err
+		}
+		parent := filepath.Dir(current)
+		if parent == current {
+			return filepath.Clean(path), nil
+		}
+		missing = append(missing, filepath.Base(current))
+		current = parent
+	}
+}

act/container/docker_run_test.go

@@ -11,6 +11,8 @@ import (
 	"errors"
 	"io"
 	"net"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -375,3 +377,40 @@ func TestCheckVolumes(t *testing.T) {
 		})
 	}
 }
+
+func TestCheckVolumesRejectsEscapingHostPaths(t *testing.T) {
+	logger, _ := test.NewNullLogger()
+	ctx := common.WithLogger(context.Background(), logger)
+
+	base := t.TempDir()
+	allowed := filepath.Join(base, "allowed")
+	denied := filepath.Join(base, "denied")
+	require.NoError(t, os.MkdirAll(allowed, 0o700))
+	require.NoError(t, os.MkdirAll(denied, 0o700))
+
+	cr := &containerReference{
+		input: &NewContainerInput{
+			ValidVolumes: []string{filepath.Join(allowed, "**")},
+		},
+	}
+
+	escapingPath := allowed + string(filepath.Separator) + ".." + string(filepath.Separator) + "denied"
+	_, hostConf := cr.sanitizeConfig(ctx, &container.Config{}, &container.HostConfig{
+		Binds: []string{escapingPath + ":/mnt"},
+	})
+	assert.Empty(t, hostConf.Binds)
+
+	linkPath := filepath.Join(allowed, "link")
+	if err := os.Symlink(denied, linkPath); err != nil {
+		t.Skipf("cannot create symlink: %v", err)
+	}
+	_, hostConf = cr.sanitizeConfig(ctx, &container.Config{}, &container.HostConfig{
+		Binds: []string{linkPath + ":/mnt"},
+	})
+	assert.Empty(t, hostConf.Binds)
+
+	_, hostConf = cr.sanitizeConfig(ctx, &container.Config{}, &container.HostConfig{
+		Binds: []string{filepath.Join(linkPath, "missing") + ":/mnt"},
+	})
+	assert.Empty(t, hostConf.Binds)
+}

act/container/host_environment.go

@@ -37,13 +37,13 @@ type HostEnvironment struct {
 	TmpDir    string
 	ToolCache string
 	Workdir   string
-	// BindWorkdir is true when the app runner mounts the workspace on the host and
-	// deletes the task directory after the job; host teardown must not remove Workdir.
-	BindWorkdir bool
-	ActPath     string
-	CleanUp     func()
-	StdOut      io.Writer
-	AllocatePTY bool // allocate a pseudo-TTY for each step's process
+	// CleanWorkdir means teardown owns Workdir and may delete it. Leave false
+	// when Workdir points at a caller-owned checkout (e.g. `act` local mode).
+	CleanWorkdir bool
+	ActPath      string
+	CleanUp      func()
+	StdOut       io.Writer
+	AllocatePTY  bool // allocate a pseudo-TTY for each step's process
 
 	mu          sync.Mutex
 	runningPIDs map[int]struct{}
@@ -483,7 +483,7 @@ func (e *HostEnvironment) Remove() common.Executor {
 			logger.Warnf("failed to remove host misc state %s: %v", e.Path, err)
 			errs = append(errs, err)
 		}
-		if !e.BindWorkdir && e.Workdir != "" {
+		if e.CleanWorkdir {
 			if err := removePathWithRetry(ctx, e.Workdir); err != nil {
 				logger.Warnf("failed to remove host workspace %s: %v", e.Workdir, err)
 				errs = append(errs, err)

act/container/host_environment_test.go

@@ -141,7 +141,7 @@ func TestHostEnvironmentAllocatePTY(t *testing.T) {
 	}
 }
 
-func TestHostEnvironmentRemoveCleansWorkdir(t *testing.T) {
+func TestHostEnvironmentRemovePreservesWorkdirByDefault(t *testing.T) {
 	logger := logrus.New()
 	ctx := common.WithLogger(context.Background(), logrus.NewEntry(logger))
 	base := t.TempDir()
@@ -152,9 +152,8 @@ func TestHostEnvironmentRemoveCleansWorkdir(t *testing.T) {
 	require.NoError(t, os.MkdirAll(workdir, 0o700))
 
 	e := &HostEnvironment{
-		Path:        path,
-		Workdir:     workdir,
-		BindWorkdir: false,
+		Path:    path,
+		Workdir: workdir,
 		CleanUp: func() {
 			_ = os.RemoveAll(miscRoot)
 		},
@@ -162,10 +161,10 @@ func TestHostEnvironmentRemoveCleansWorkdir(t *testing.T) {
 	}
 	require.NoError(t, e.Remove()(ctx))
 	_, err := os.Stat(workdir)
-	assert.ErrorIs(t, err, os.ErrNotExist)
+	require.NoError(t, err)
 }
 
-func TestHostEnvironmentRemoveSkipsWorkdirWhenBindWorkdir(t *testing.T) {
+func TestHostEnvironmentRemoveCleansWorkdirWhenOwned(t *testing.T) {
 	logger := logrus.New()
 	ctx := common.WithLogger(context.Background(), logrus.NewEntry(logger))
 	base := t.TempDir()
@@ -176,9 +175,9 @@ func TestHostEnvironmentRemoveSkipsWorkdirWhenBindWorkdir(t *testing.T) {
 	require.NoError(t, os.MkdirAll(workdir, 0o700))
 
 	e := &HostEnvironment{
-		Path:        path,
-		Workdir:     workdir,
-		BindWorkdir: true,
+		Path:         path,
+		Workdir:      workdir,
+		CleanWorkdir: true,
 		CleanUp: func() {
 			_ = os.RemoveAll(miscRoot)
 		},
@@ -186,5 +185,5 @@ func TestHostEnvironmentRemoveSkipsWorkdirWhenBindWorkdir(t *testing.T) {
 	}
 	require.NoError(t, e.Remove()(ctx))
 	_, err := os.Stat(workdir)
-	require.NoError(t, err)
+	assert.ErrorIs(t, err, os.ErrNotExist)
 }