@@ -142,8 +142,8 @@ func newSnapshotterController(ctx context.Context, rt http.RoundTripper, opt Opt

 		return nil, err

 	}

 	frontends := map[string]frontend.Frontend{

-		"dockerfile.v0": forwarder.NewGatewayForwarder(wc, dockerfile.Build),

-		"gateway.v0":    gateway.NewGatewayFrontend(wc),

+		"dockerfile.v0": forwarder.NewGatewayForwarder(wc.Infos(), dockerfile.Build),

+		"gateway.v0":    gateway.NewGatewayFrontend(wc.Infos()),

 	}

 	return control.NewController(control.Opt{

@@ -364,8 +364,8 @@ func newGraphDriverController(ctx context.Context, rt http.RoundTripper, opt Opt

 	wc.Add(w)

 	frontends := map[string]frontend.Frontend{

-		"dockerfile.v0": forwarder.NewGatewayForwarder(wc, dockerfile.Build),

-		"gateway.v0":    gateway.NewGatewayFrontend(wc),

+		"dockerfile.v0": forwarder.NewGatewayForwarder(wc.Infos(), dockerfile.Build),

+		"gateway.v0":    gateway.NewGatewayFrontend(wc.Infos()),

 	}

 	return control.NewController(control.Opt{

@@ -60,7 +60,7 @@ require (

 	github.com/miekg/dns v1.1.43

 	github.com/mistifyio/go-zfs/v3 v3.0.1

 	github.com/mitchellh/copystructure v1.2.0

-	github.com/moby/buildkit v0.12.5-0.20231208203051-3b6880d2a00f // v0.12 branch (v0.12.5-dev)

+	github.com/moby/buildkit v0.12.5

 	github.com/moby/ipvs v1.1.0

 	github.com/moby/locker v1.0.1

 	github.com/moby/patternmatcher v0.6.0

@@ -902,8 +902,8 @@ github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zx

 github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=

 github.com/mndrix/tap-go v0.0.0-20171203230836-629fa407e90b/go.mod h1:pzzDgJWZ34fGzaAZGFW22KVZDfyrYW+QABMrWnJBnSs=

 github.com/moby/buildkit v0.8.1/go.mod h1:/kyU1hKy/aYCuP39GZA9MaKioovHku57N6cqlKZIaiQ=

-github.com/moby/buildkit v0.12.5-0.20231208203051-3b6880d2a00f h1:nYPkpfWrlQznHPLNrXxXIQMaTlmnsSBiiRTgnQ5hrZ0=

-github.com/moby/buildkit v0.12.5-0.20231208203051-3b6880d2a00f/go.mod h1:XG74uz06nPWQpnxYwgCryrVidvor0+ElUxGosbZPQG4=

+github.com/moby/buildkit v0.12.5 h1:RNHH1l3HDhYyZafr5EgstEu8aGNCwyfvMtrQDtjH9T0=

+github.com/moby/buildkit v0.12.5/go.mod h1:YGwjA2loqyiYfZeEo8FtI7z4x5XponAaIWsWcSjWwso=

 github.com/moby/ipvs v1.1.0 h1:ONN4pGaZQgAx+1Scz5RvWV4Q7Gb+mvfRh3NsPS+1XQQ=

 github.com/moby/ipvs v1.1.0/go.mod h1:4VJMWuf098bsUMmZEiD4Tjk/O7mOn3l1PTD3s4OoYAs=

 github.com/moby/locker v1.0.1 h1:fOXqR41zeveg4fFODix+1Ch4mj/gT0NE1XJbp/epuBg=

@@ -405,6 +405,9 @@ func (c *Controller) Solve(ctx context.Context, req *controlapi.SolveRequest) (*

 	var cacheImports []frontend.CacheOptionsEntry

 	for _, im := range req.Cache.Imports {

+		if im == nil {

+			continue

+		}

 		cacheImports = append(cacheImports, frontend.CacheOptionsEntry{

 			Type:  im.Type,

 			Attrs: im.Attrs,

@@ -6,8 +6,9 @@ import (

 	"net"

 	"syscall"

+	"github.com/containerd/containerd/mount"

+	"github.com/docker/docker/pkg/idtools"

 	resourcestypes "github.com/moby/buildkit/executor/resources/types"

-	"github.com/moby/buildkit/snapshot"

 	"github.com/moby/buildkit/solver/pb"

 )

@@ -28,8 +29,13 @@ type Meta struct {

 	RemoveMountStubsRecursive bool

 }

+type MountableRef interface {

+	Mount() ([]mount.Mount, func() error, error)

+	IdentityMapping() *idtools.IdentityMapping

+}

+

 type Mountable interface {

-	Mount(ctx context.Context, readonly bool) (snapshot.Mountable, error)

+	Mount(ctx context.Context, readonly bool) (MountableRef, error)

 }

 type Mount struct {

@@ -12,7 +12,6 @@ import (

 	"github.com/containerd/containerd/namespaces"

 	"github.com/containerd/containerd/oci"

 	"github.com/containerd/containerd/pkg/userns"

-	"github.com/containerd/continuity/fs"

 	"github.com/docker/docker/pkg/idtools"

 	"github.com/mitchellh/hashstructure/v2"

 	"github.com/moby/buildkit/executor"

@@ -215,6 +214,7 @@ func GenerateSpec(ctx context.Context, meta executor.Meta, mounts []executor.Mou

 type mountRef struct {

 	mount   mount.Mount

 	unmount func() error

+	subRefs map[string]mountRef

 }

 type submounts struct {

@@ -230,12 +230,19 @@ func (s *submounts) subMount(m mount.Mount, subPath string) (mount.Mount, error)

 	}

 	h, err := hashstructure.Hash(m, hashstructure.FormatV2, nil)

 	if err != nil {

-		return mount.Mount{}, nil

+		return mount.Mount{}, err

 	}

 	if mr, ok := s.m[h]; ok {

-		sm, err := sub(mr.mount, subPath)

+		if sm, ok := mr.subRefs[subPath]; ok {

+			return sm.mount, nil

+		}

+		sm, unmount, err := sub(mr.mount, subPath)

 		if err != nil {

-			return mount.Mount{}, nil

+			return mount.Mount{}, err

+		}

+		mr.subRefs[subPath] = mountRef{

+			mount:   sm,

+			unmount: unmount,

 		}

 		return sm, nil

 	}

@@ -261,12 +268,17 @@ func (s *submounts) subMount(m mount.Mount, subPath string) (mount.Mount, error)

 			Options: opts,

 		},

 		unmount: lm.Unmount,

+		subRefs: map[string]mountRef{},

 	}

-	sm, err := sub(s.m[h].mount, subPath)

+	sm, unmount, err := sub(s.m[h].mount, subPath)

 	if err != nil {

 		return mount.Mount{}, err

 	}

+	s.m[h].subRefs[subPath] = mountRef{

+		mount:   sm,

+		unmount: unmount,

+	}

 	return sm, nil

 }

@@ -276,6 +288,9 @@ func (s *submounts) cleanup() {

 	for _, m := range s.m {

 		func(m mountRef) {

 			go func() {

+				for _, sm := range m.subRefs {

+					sm.unmount()

+				}

 				m.unmount()

 				wg.Done()

 			}()

@@ -284,15 +299,6 @@ func (s *submounts) cleanup() {

 	wg.Wait()

 }

-func sub(m mount.Mount, subPath string) (mount.Mount, error) {

-	src, err := fs.RootPath(m.Source, subPath)

-	if err != nil {

-		return mount.Mount{}, err

-	}

-	m.Source = src

-	return m, nil

-}

-

 func specMapping(s []idtools.IDMap) []specs.LinuxIDMapping {

 	var ids []specs.LinuxIDMapping

 	for _, item := range s {

new file mode 100644

@@ -0,0 +1,15 @@

+package oci

+

+import (

+	"github.com/containerd/containerd/mount"

+	"github.com/containerd/continuity/fs"

+)

+

+func sub(m mount.Mount, subPath string) (mount.Mount, func() error, error) {

+	src, err := fs.RootPath(m.Source, subPath)

+	if err != nil {

+		return mount.Mount{}, nil, err

+	}

+	m.Source = src

+	return m, func() error { return nil }, nil

+}

new file mode 100644

@@ -0,0 +1,57 @@

+//go:build linux

+// +build linux

+

+package oci

+

+import (

+	"os"

+	"strconv"

+

+	"github.com/containerd/containerd/mount"

+	"github.com/containerd/continuity/fs"

+	"github.com/moby/buildkit/snapshot"

+	"github.com/pkg/errors"

+	"golang.org/x/sys/unix"

+)

+

+func sub(m mount.Mount, subPath string) (mount.Mount, func() error, error) {

+	var retries = 10

+	root := m.Source

+	for {

+		src, err := fs.RootPath(root, subPath)

+		if err != nil {

+			return mount.Mount{}, nil, err

+		}

+		// similar to runc.WithProcfd

+		fh, err := os.OpenFile(src, unix.O_PATH|unix.O_CLOEXEC, 0)

+		if err != nil {

+			return mount.Mount{}, nil, err

+		}

+

+		fdPath := "/proc/self/fd/" + strconv.Itoa(int(fh.Fd()))

+		if resolved, err := os.Readlink(fdPath); err != nil {

+			fh.Close()

+			return mount.Mount{}, nil, err

+		} else if resolved != src {

+			retries--

+			if retries <= 0 {

+				fh.Close()

+				return mount.Mount{}, nil, errors.Errorf("unable to safely resolve subpath %s", subPath)

+			}

+			fh.Close()

+			continue

+		}

+

+		m.Source = fdPath

+		lm := snapshot.LocalMounterWithMounts([]mount.Mount{m}, snapshot.ForceRemount())

+		mp, err := lm.Mount()

+		if err != nil {

+			fh.Close()

+			return mount.Mount{}, nil, err

+		}

+		m.Source = mp

+		fh.Close() // release the fd, we don't need it anymore

+

+		return m, lm.Unmount, nil

+	}

+}

@@ -7,7 +7,9 @@ import (

 	"fmt"

 	"path/filepath"

+	"github.com/containerd/containerd/mount"

 	"github.com/containerd/containerd/oci"

+	"github.com/containerd/continuity/fs"

 	"github.com/docker/docker/pkg/idtools"

 	"github.com/moby/buildkit/solver/pb"

 	specs "github.com/opencontainers/runtime-spec/specs-go"

@@ -67,3 +69,12 @@ func getTracingSocket() string {

 func cgroupV2NamespaceSupported() bool {

 	return false

 }

+

+func sub(m mount.Mount, subPath string) (mount.Mount, func() error, error) {

+	src, err := fs.RootPath(m.Source, subPath)

+	if err != nil {

+		return mount.Mount{}, nil, err

+	}

+	m.Source = src

+	return m, func() error { return nil }, nil

+}

@@ -5,6 +5,7 @@ import (

 	"errors"

 	"os"

 	"path/filepath"

+	"strings"

 	"syscall"

 	"github.com/containerd/continuity/fs"

@@ -43,7 +44,7 @@ func MountStubsCleaner(ctx context.Context, dir string, mounts []Mount, recursiv

 			}

 			realPathNext := filepath.Dir(realPath)

-			if realPath == realPathNext {

+			if realPath == realPathNext || realPathNext == dir {

 				break

 			}

 			realPath = realPathNext

@@ -52,6 +53,11 @@ func MountStubsCleaner(ctx context.Context, dir string, mounts []Mount, recursiv

 	return func() {

 		for _, p := range paths {

+			p, err := fs.RootPath(dir, strings.TrimPrefix(p, dir))

+			if err != nil {

+				continue

+			}

+

 			st, err := os.Lstat(p)

 			if err != nil {

 				continue

@@ -70,8 +76,12 @@ func MountStubsCleaner(ctx context.Context, dir string, mounts []Mount, recursiv

 			// Back up the timestamps of the dir for reproducible builds

 			// https://github.com/moby/buildkit/issues/3148

-			dir := filepath.Dir(p)

-			dirSt, err := os.Stat(dir)

+			parent := filepath.Dir(p)

+			if realPath, err := fs.RootPath(dir, strings.TrimPrefix(parent, dir)); err != nil || realPath != parent {

+				continue

+			}

+

+			dirSt, err := os.Stat(parent)

 			if err != nil {

 				bklog.G(ctx).WithError(err).Warnf("Failed to stat %q (parent of mount stub %q)", dir, p)

 				continue

@@ -88,7 +98,7 @@ func MountStubsCleaner(ctx context.Context, dir string, mounts []Mount, recursiv

 			}

 			// Restore the timestamps of the dir

-			if err := os.Chtimes(dir, atime, mtime); err != nil {

+			if err := os.Chtimes(parent, atime, mtime); err != nil {

 				bklog.G(ctx).WithError(err).Warnf("Failed to restore time time mount stub timestamp (os.Chtimes(%q, %v, %v))", dir, atime, mtime)

 			}

 		}

@@ -17,6 +17,18 @@ func ParsePlatforms(meta map[string][]byte) (Platforms, error) {

 				return Platforms{}, errors.Wrapf(err, "failed to parse platforms passed to provenance processor")

 			}

 		}

+		if len(ps.Platforms) == 0 {

+			return Platforms{}, errors.Errorf("invalid empty platforms index for exporter")

+		}

+		for i, p := range ps.Platforms {

+			if p.ID == "" {

+				return Platforms{}, errors.Errorf("invalid empty platform key for exporter")

+			}

+			if p.Platform.OS == "" || p.Platform.Architecture == "" {

+				return Platforms{}, errors.Errorf("invalid platform value %v for exporter", p.Platform)

+			}

+			ps.Platforms[i].Platform = platforms.Normalize(p.Platform)

+		}

 		return ps, nil

 	}

@@ -36,6 +48,8 @@ func ParsePlatforms(meta map[string][]byte) (Platforms, error) {

 				OSFeatures:   img.OSFeatures,

 				Variant:      img.Variant,

 			}

+		} else if img.OS != "" || img.Architecture != "" {

+			return Platforms{}, errors.Errorf("invalid image config: os and architecture must be specified together")

 		}

 	}

 	p = platforms.Normalize(p)

@@ -569,11 +569,27 @@ func parseHistoryFromConfig(dt []byte) ([]ocispecs.History, error) {

 }

 func patchImageConfig(dt []byte, descs []ocispecs.Descriptor, history []ocispecs.History, cache []byte, epoch *time.Time) ([]byte, error) {

+	var img ocispecs.Image

+	if err := json.Unmarshal(dt, &img); err != nil {

+		return nil, errors.Wrap(err, "invalid image config for export")

+	}

+

 	m := map[string]json.RawMessage{}

 	if err := json.Unmarshal(dt, &m); err != nil {

 		return nil, errors.Wrap(err, "failed to parse image config for patch")

 	}

+	if m == nil {

+		return nil, errors.Errorf("invalid null image config for export")

+	}

+

+	if img.OS == "" {

+		return nil, errors.Errorf("invalid image config for export: missing os")

+	}

+	if img.Architecture == "" {

+		return nil, errors.Errorf("invalid image config for export: missing architecture")

+	}

+

 	var rootFS ocispecs.RootFS

 	rootFS.Type = "layers"

 	for _, desc := range descs {

@@ -4,6 +4,7 @@ import (

 	"context"

 	"github.com/moby/buildkit/client/llb"

+	"github.com/moby/buildkit/executor"

 	gw "github.com/moby/buildkit/frontend/gateway/client"

 	"github.com/moby/buildkit/session"

 	"github.com/moby/buildkit/solver"

@@ -17,7 +18,7 @@ type Result = result.Result[solver.ResultProxy]

 type Attestation = result.Attestation[solver.ResultProxy]

 type Frontend interface {

-	Solve(ctx context.Context, llb FrontendLLBBridge, opt map[string]string, inputs map[string]*pb.Definition, sid string, sm *session.Manager) (*Result, error)

+	Solve(ctx context.Context, llb FrontendLLBBridge, exec executor.Executor, opt map[string]string, inputs map[string]*pb.Definition, sid string, sm *session.Manager) (*Result, error)

 }

 type FrontendLLBBridge interface {

@@ -30,8 +30,14 @@ func AttestationToPB[T any](a *result.Attestation[T]) (*pb.Attestation, error) {

 }

 func AttestationFromPB[T any](a *pb.Attestation) (*result.Attestation[T], error) {

+	if a == nil {

+		return nil, errors.Errorf("invalid nil attestation")

+	}

 	subjects := make([]result.InTotoSubject, len(a.InTotoSubjects))

 	for i, subject := range a.InTotoSubjects {

+		if subject == nil {

+			return nil, errors.Errorf("invalid nil attestation subject")

+		}

 		subjects[i] = result.InTotoSubject{

 			Kind:   subject.Kind,

 			Name:   subject.Name,

@@ -47,7 +47,7 @@ type Mount struct {

 	WorkerRef *worker.WorkerRef

 }

-func NewContainer(ctx context.Context, w worker.Worker, sm *session.Manager, g session.Group, req NewContainerRequest) (client.Container, error) {

+func NewContainer(ctx context.Context, cm cache.Manager, exec executor.Executor, sm *session.Manager, g session.Group, req NewContainerRequest) (client.Container, error) {

 	ctx, cancel := context.WithCancel(ctx)

 	eg, ctx := errgroup.WithContext(ctx)

 	platform := opspb.Platform{

@@ -63,7 +63,7 @@ func NewContainer(ctx context.Context, w worker.Worker, sm *session.Manager, g s

 		hostname:   req.Hostname,

 		extraHosts: req.ExtraHosts,

 		platform:   platform,

-		executor:   w.Executor(),

+		executor:   exec,

 		sm:         sm,

 		group:      g,

 		errGroup:   eg,

@@ -86,9 +86,8 @@ func NewContainer(ctx context.Context, w worker.Worker, sm *session.Manager, g s

 	}

 	name := fmt.Sprintf("container %s", req.ContainerID)

-	mm := mounts.NewMountManager(name, w.CacheManager(), sm)

-	p, err := PrepareMounts(ctx, mm, w.CacheManager(), g, "", mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

-		cm := w.CacheManager()

+	mm := mounts.NewMountManager(name, cm, sm)

+	p, err := PrepareMounts(ctx, mm, cm, g, "", mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

 		if m.Input != opspb.Empty {

 			cm = refs[m.Input].Worker.CacheManager()

 		}

@@ -6,6 +6,7 @@ import (

 	cacheutil "github.com/moby/buildkit/cache/util"

 	"github.com/moby/buildkit/client/llb"

+	"github.com/moby/buildkit/executor"

 	"github.com/moby/buildkit/frontend"

 	"github.com/moby/buildkit/frontend/gateway/client"

 	"github.com/moby/buildkit/frontend/gateway/container"

@@ -26,7 +27,7 @@ import (

 	"golang.org/x/sync/errgroup"

 )

-func LLBBridgeToGatewayClient(ctx context.Context, llbBridge frontend.FrontendLLBBridge, opts map[string]string, inputs map[string]*opspb.Definition, w worker.Infos, sid string, sm *session.Manager) (*BridgeClient, error) {

+func LLBBridgeToGatewayClient(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, opts map[string]string, inputs map[string]*opspb.Definition, w worker.Infos, sid string, sm *session.Manager) (*BridgeClient, error) {

 	bc := &BridgeClient{

 		opts:              opts,

 		inputs:            inputs,

@@ -35,6 +36,7 @@ func LLBBridgeToGatewayClient(ctx context.Context, llbBridge frontend.FrontendLL

 		sm:                sm,

 		workers:           w,

 		workerRefByID:     make(map[string]*worker.WorkerRef),

+		executor:          exec,

 	}

 	bc.buildOpts = bc.loadBuildOpts()

 	return bc, nil

@@ -52,6 +54,7 @@ type BridgeClient struct {

 	workerRefByID map[string]*worker.WorkerRef

 	buildOpts     client.BuildOpts

 	ctrs          []client.Container

+	executor      executor.Executor

 }

 func (c *BridgeClient) Solve(ctx context.Context, req client.SolveRequest) (*client.Result, error) {

@@ -293,13 +296,13 @@ func (c *BridgeClient) NewContainer(ctx context.Context, req client.NewContainer

 		return nil, err

 	}

-	w, err := c.workers.GetDefault()

+	cm, err := c.workers.DefaultCacheManager()

 	if err != nil {

 		return nil, err

 	}

 	group := session.NewGroup(c.sid)

-	ctr, err := container.NewContainer(ctx, w, c.sm, group, ctrReq)

+	ctr, err := container.NewContainer(ctx, cm, c.executor, c.sm, group, ctrReq)

 	if err != nil {

 		return nil, err

 	}

@@ -3,6 +3,7 @@ package forwarder

 import (

 	"context"

+	"github.com/moby/buildkit/executor"

 	"github.com/moby/buildkit/frontend"

 	"github.com/moby/buildkit/frontend/gateway/client"

 	"github.com/moby/buildkit/session"

@@ -22,8 +23,8 @@ type GatewayForwarder struct {

 	f       client.BuildFunc

 }

-func (gf *GatewayForwarder) Solve(ctx context.Context, llbBridge frontend.FrontendLLBBridge, opts map[string]string, inputs map[string]*pb.Definition, sid string, sm *session.Manager) (retRes *frontend.Result, retErr error) {

-	c, err := LLBBridgeToGatewayClient(ctx, llbBridge, opts, inputs, gf.workers, sid, sm)

+func (gf *GatewayForwarder) Solve(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, opts map[string]string, inputs map[string]*pb.Definition, sid string, sm *session.Manager) (retRes *frontend.Result, retErr error) {

+	c, err := LLBBridgeToGatewayClient(ctx, llbBridge, exec, opts, inputs, gf.workers, sid, sm)

 	if err != nil {

 		return nil, err

 	}

@@ -86,7 +86,7 @@ func filterPrefix(opts map[string]string, pfx string) map[string]string {

 	return m

 }

-func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.FrontendLLBBridge, opts map[string]string, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) (*frontend.Result, error) {

+func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, opts map[string]string, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) (*frontend.Result, error) {

 	source, ok := opts[keySource]

 	if !ok {

 		return nil, errors.Errorf("no source specified for gateway")

@@ -141,7 +141,7 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten

 			}

 		}

 	} else {

-		c, err := forwarder.LLBBridgeToGatewayClient(ctx, llbBridge, opts, inputs, gf.workers, sid, sm)

+		c, err := forwarder.LLBBridgeToGatewayClient(ctx, llbBridge, exec, opts, inputs, gf.workers, sid, sm)

 		if err != nil {

 			return nil, err

 		}

@@ -281,18 +281,13 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten

 		}

 	}

-	lbf, ctx, err := serveLLBBridgeForwarder(ctx, llbBridge, gf.workers, inputs, sid, sm)

+	lbf, ctx, err := serveLLBBridgeForwarder(ctx, llbBridge, exec, gf.workers, inputs, sid, sm)

 	defer lbf.conn.Close() //nolint

 	if err != nil {

 		return nil, err

 	}

 	defer lbf.Discard()

-	w, err := gf.workers.GetDefault()

-	if err != nil {

-		return nil, err

-	}

-

 	mdmnt, release, err := metadataMount(frontendDef)

 	if err != nil {

 		return nil, err

@@ -305,7 +300,7 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten

 		mnts = append(mnts, *mdmnt)

 	}

-	_, err = w.Executor().Run(ctx, "", container.MountWithSession(rootFS, session.NewGroup(sid)), mnts, executor.ProcessInfo{Meta: meta, Stdin: lbf.Stdin, Stdout: lbf.Stdout, Stderr: os.Stderr}, nil)

+	_, err = exec.Run(ctx, "", container.MountWithSession(rootFS, session.NewGroup(sid)), mnts, executor.ProcessInfo{Meta: meta, Stdin: lbf.Stdin, Stdout: lbf.Stdout, Stderr: os.Stderr}, nil)

 	if err != nil {

 		if errdefs.IsCanceled(ctx, err) && lbf.isErrServerClosed {

 			err = errors.Errorf("frontend grpc server closed unexpectedly")

@@ -434,11 +429,11 @@ func (lbf *llbBridgeForwarder) Result() (*frontend.Result, error) {

 	return lbf.result, nil

 }

-func NewBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) LLBBridgeForwarder {

-	return newBridgeForwarder(ctx, llbBridge, workers, inputs, sid, sm)

+func NewBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) LLBBridgeForwarder {

+	return newBridgeForwarder(ctx, llbBridge, exec, workers, inputs, sid, sm)

 }

-func newBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) *llbBridgeForwarder {

+func newBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) *llbBridgeForwarder {

 	lbf := &llbBridgeForwarder{

 		callCtx:       ctx,

 		llbBridge:     llbBridge,

@@ -451,13 +446,14 @@ func newBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridg

 		sid:           sid,

 		sm:            sm,

 		ctrs:          map[string]gwclient.Container{},

+		executor:      exec,

 	}

 	return lbf

 }

-func serveLLBBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) (*llbBridgeForwarder, context.Context, error) {

+func serveLLBBridgeForwarder(ctx context.Context, llbBridge frontend.FrontendLLBBridge, exec executor.Executor, workers worker.Infos, inputs map[string]*opspb.Definition, sid string, sm *session.Manager) (*llbBridgeForwarder, context.Context, error) {

 	ctx, cancel := context.WithCancel(ctx)

-	lbf := newBridgeForwarder(ctx, llbBridge, workers, inputs, sid, sm)

+	lbf := newBridgeForwarder(ctx, llbBridge, exec, workers, inputs, sid, sm)

 	server := grpc.NewServer(grpc.UnaryInterceptor(grpcerrors.UnaryServerInterceptor), grpc.StreamInterceptor(grpcerrors.StreamServerInterceptor))

 	grpc_health_v1.RegisterHealthServer(server, health.NewServer())

 	pb.RegisterLLBBridgeServer(server, lbf)

@@ -552,6 +548,7 @@ type llbBridgeForwarder struct {

 	isErrServerClosed bool

 	sid               string

 	sm                *session.Manager

+	executor          executor.Executor

 	*pipe

 	ctrs   map[string]gwclient.Container

 	ctrsMu sync.Mutex

@@ -646,12 +643,21 @@ func (lbf *llbBridgeForwarder) registerResultIDs(results ...solver.Result) (ids

 func (lbf *llbBridgeForwarder) Solve(ctx context.Context, req *pb.SolveRequest) (*pb.SolveResponse, error) {

 	var cacheImports []frontend.CacheOptionsEntry

 	for _, e := range req.CacheImports {

+		if e == nil {

+			return nil, errors.Errorf("invalid nil cache import")

+		}

 		cacheImports = append(cacheImports, frontend.CacheOptionsEntry{

 			Type:  e.Type,

 			Attrs: e.Attrs,

 		})

 	}

+	for _, p := range req.SourcePolicies {

+		if p == nil {

+			return nil, errors.Errorf("invalid nil source policy")

+		}

+	}

+

 	ctx = tracing.ContextWithSpanFromContext(ctx, lbf.callCtx)

 	res, err := lbf.llbBridge.Solve(ctx, frontend.SolveRequest{

 		Evaluate:       req.Evaluate,

@@ -1033,7 +1039,7 @@ func (lbf *llbBridgeForwarder) NewContainer(ctx context.Context, in *pb.NewConta

 	// and we want the context to live for the duration of the container.

 	group := session.NewGroup(lbf.sid)

-	w, err := lbf.workers.GetDefault()

+	cm, err := lbf.workers.DefaultCacheManager()

 	if err != nil {

 		return nil, stack.Enable(err)

 	}

@@ -1043,7 +1049,7 @@ func (lbf *llbBridgeForwarder) NewContainer(ctx context.Context, in *pb.NewConta

 		return nil, stack.Enable(err)

 	}

-	ctr, err := container.NewContainer(context.Background(), w, lbf.sm, group, ctrReq)

+	ctr, err := container.NewContainer(context.Background(), cm, lbf.executor, lbf.sm, group, ctrReq)

 	if err != nil {

 		return nil, stack.Enable(err)

 	}

@@ -1077,6 +1083,12 @@ func (lbf *llbBridgeForwarder) ReleaseContainer(ctx context.Context, in *pb.Rele

 }

 func (lbf *llbBridgeForwarder) Warn(ctx context.Context, in *pb.WarnRequest) (*pb.WarnResponse, error) {

+	// validate ranges are valid

+	for _, r := range in.Ranges {

+		if r == nil {

+			return nil, status.Errorf(codes.InvalidArgument, "invalid source range")

+		}

+	}

 	err := lbf.llbBridge.Warn(ctx, in.Digest, string(in.Short), frontend.WarnOpts{

 		Level:      int(in.Level),

 		SourceInfo: in.Info,

@@ -11,22 +11,39 @@ type Mounter interface {

 	Unmount() error

 }

+type LocalMounterOpt func(*localMounter)

+

 // LocalMounter is a helper for mounting mountfactory to temporary path. In

 // addition it can mount binds without privileges

-func LocalMounter(mountable Mountable) Mounter {

-	return &localMounter{mountable: mountable}

+func LocalMounter(mountable Mountable, opts ...LocalMounterOpt) Mounter {

+	lm := &localMounter{mountable: mountable}

+	for _, opt := range opts {

+		opt(lm)

+	}

+	return lm

 }

 // LocalMounterWithMounts is a helper for mounting to temporary path. In

 // addition it can mount binds without privileges

-func LocalMounterWithMounts(mounts []mount.Mount) Mounter {

-	return &localMounter{mounts: mounts}

+func LocalMounterWithMounts(mounts []mount.Mount, opts ...LocalMounterOpt) Mounter {

+	lm := &localMounter{mounts: mounts}

+	for _, opt := range opts {

+		opt(lm)

+	}

+	return lm

 }

 type localMounter struct {

-	mu        sync.Mutex

-	mounts    []mount.Mount

-	mountable Mountable

-	target    string

-	release   func() error

+	mu           sync.Mutex

+	mounts       []mount.Mount

+	mountable    Mountable

+	target       string

+	release      func() error

+	forceRemount bool

+}

+

+func ForceRemount() LocalMounterOpt {

+	return func(lm *localMounter) {

+		lm.forceRemount = true

+	}

 }

@@ -5,6 +5,7 @@ package snapshot

 import (

 	"os"

+	"path/filepath"

 	"syscall"

 	"github.com/containerd/containerd/mount"

@@ -34,30 +35,48 @@ func (lm *localMounter) Mount() (string, error) {

 		}

 	}

+	var isFile bool

 	if len(lm.mounts) == 1 && (lm.mounts[0].Type == "bind" || lm.mounts[0].Type == "rbind") {

-		ro := false

-		for _, opt := range lm.mounts[0].Options {

-			if opt == "ro" {

-				ro = true

-				break

+		if !lm.forceRemount {

+			ro := false

+			for _, opt := range lm.mounts[0].Options {

+				if opt == "ro" {

+					ro = true

+					break

+				}

 			}

+			if !ro {

+				return lm.mounts[0].Source, nil

+			}

+		}

+		fi, err := os.Stat(lm.mounts[0].Source)

+		if err != nil {

+			return "", err

 		}

-		if !ro {

-			return lm.mounts[0].Source, nil

+		if !fi.IsDir() {

+			isFile = true

 		}

 	}

-	dir, err := os.MkdirTemp("", "buildkit-mount")

+	dest, err := os.MkdirTemp("", "buildkit-mount")

 	if err != nil {

 		return "", errors.Wrap(err, "failed to create temp dir")

 	}

-	if err := mount.All(lm.mounts, dir); err != nil {

-		os.RemoveAll(dir)

-		return "", errors.Wrapf(err, "failed to mount %s: %+v", dir, lm.mounts)

+	if isFile {

+		dest = filepath.Join(dest, "file")

+		if err := os.WriteFile(dest, []byte{}, 0644); err != nil {

+			os.RemoveAll(dest)

+			return "", errors.Wrap(err, "failed to create temp file")

+		}

+	}

+

+	if err := mount.All(lm.mounts, dest); err != nil {

+		os.RemoveAll(dest)

+		return "", errors.Wrapf(err, "failed to mount %s: %+v", dest, lm.mounts)

 	}

-	lm.target = dir

-	return dir, nil

+	lm.target = dest

+	return dest, nil

 }

 func (lm *localMounter) Unmount() error {

@@ -10,14 +10,11 @@ import (

 	"github.com/containerd/containerd/pkg/userns"

 	"github.com/containerd/containerd/snapshots"

 	"github.com/docker/docker/pkg/idtools"

+	"github.com/moby/buildkit/executor"

 	"github.com/pkg/errors"

 )

-type Mountable interface {

-	// ID() string

-	Mount() ([]mount.Mount, func() error, error)

-	IdentityMapping() *idtools.IdentityMapping

-}

+type Mountable = executor.MountableRef

 // Snapshotter defines interface that any snapshot implementation should satisfy

 type Snapshotter interface {

@@ -11,6 +11,8 @@ import (

 	"github.com/moby/buildkit/cache/remotecache"

 	"github.com/moby/buildkit/client"

 	"github.com/moby/buildkit/client/llb"

+	"github.com/moby/buildkit/executor"

+	resourcestypes "github.com/moby/buildkit/executor/resources/types"

 	"github.com/moby/buildkit/frontend"

 	gw "github.com/moby/buildkit/frontend/gateway/client"

 	"github.com/moby/buildkit/identity"

@@ -23,6 +25,7 @@ import (

 	"github.com/moby/buildkit/sourcepolicy"

 	spb "github.com/moby/buildkit/sourcepolicy/pb"

 	"github.com/moby/buildkit/util/bklog"

+	"github.com/moby/buildkit/util/entitlements"

 	"github.com/moby/buildkit/util/flightcontrol"

 	"github.com/moby/buildkit/util/progress"

 	"github.com/moby/buildkit/worker"

@@ -39,6 +42,10 @@ type llbBridge struct {

 	cms                       map[string]solver.CacheManager

 	cmsMu                     sync.Mutex

 	sm                        *session.Manager

+

+	executorOnce sync.Once

+	executorErr  error

+	executor     executor.Executor

 }

 func (b *llbBridge) Warn(ctx context.Context, dgst digest.Digest, msg string, opts frontend.WarnOpts) error {

@@ -79,6 +86,14 @@ func (b *llbBridge) loadResult(ctx context.Context, def *pb.Definition, cacheImp

 	}

 	var polEngine SourcePolicyEvaluator

 	if srcPol != nil || len(pol) > 0 {

+		for _, p := range pol {

+			if p == nil {

+				return nil, errors.Errorf("invalid nil policy")

+			}

+			if err := validateSourcePolicy(*p); err != nil {

+				return nil, err

+			}

+		}

 		if srcPol != nil {

 			pol = append([]*spb.Policy{srcPol}, pol...)

 		}

@@ -151,6 +166,52 @@ func (b *llbBridge) loadResult(ctx context.Context, def *pb.Definition, cacheImp

 	return res, nil

 }

+func (b *llbBridge) validateEntitlements(p executor.ProcessInfo) error {

+	ent, err := loadEntitlements(b.builder)

+	if err != nil {

+		return err

+	}

+	v := entitlements.Values{

+		NetworkHost:      p.Meta.NetMode == pb.NetMode_HOST,

+		SecurityInsecure: p.Meta.SecurityMode == pb.SecurityMode_INSECURE,

+	}

+	return ent.Check(v)

+}

+

+func (b *llbBridge) Run(ctx context.Context, id string, rootfs executor.Mount, mounts []executor.Mount, process executor.ProcessInfo, started chan<- struct{}) (resourcestypes.Recorder, error) {

+	if err := b.validateEntitlements(process); err != nil {

+		return nil, err

+	}

+

+	if err := b.loadExecutor(); err != nil {

+		return nil, err

+	}

+	return b.executor.Run(ctx, id, rootfs, mounts, process, started)

+}

+

+func (b *llbBridge) Exec(ctx context.Context, id string, process executor.ProcessInfo) error {

+	if err := b.validateEntitlements(process); err != nil {

+		return err

+	}

+

+	if err := b.loadExecutor(); err != nil {

+		return err

+	}

+	return b.executor.Exec(ctx, id, process)

+}

+

+func (b *llbBridge) loadExecutor() error {

+	b.executorOnce.Do(func() {

+		w, err := b.resolveWorker()

+		if err != nil {

+			b.executorErr = err