Delete fsbridge.

Updates #1624

PiperOrigin-RevId: 492286535

pkg/sentry/fsbridge/BUILD

@@ -1,21 +0,0 @@
-load("//tools:defs.bzl", "go_library")
-
-licenses(["notice"])
-
-go_library(
-    name = "fsbridge",
-    srcs = [
-        "bridge.go",
-        "vfs.go",
-    ],
-    visibility = ["//pkg/sentry:internal"],
-    deps = [
-        "//pkg/abi/linux",
-        "//pkg/context",
-        "//pkg/fspath",
-        "//pkg/sentry/kernel/auth",
-        "//pkg/sentry/memmap",
-        "//pkg/sentry/vfs",
-        "//pkg/usermem",
-    ],
-)

pkg/sentry/fsbridge/bridge.go

@@ -1,55 +0,0 @@
-// Copyright 2020 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package fsbridge provides common interfaces to bridge between VFS1 and VFS2
-// files.
-// TODO(gvisor.dev/issue/1624): Delete this package.
-package fsbridge
-
-import (
-	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/usermem"
-)
-
-// File provides a common interface to bridge between VFS1 and VFS2 files.
-type File interface {
-	// PathnameWithDeleted returns an absolute pathname to vd, consistent with
-	// Linux's d_path(). In particular, if vd.Dentry() has been disowned,
-	// PathnameWithDeleted appends " (deleted)" to the returned pathname.
-	PathnameWithDeleted(ctx context.Context) string
-
-	// ReadFull read all contents from the file.
-	ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error)
-
-	// ConfigureMMap mutates opts to implement mmap(2) for the file.
-	ConfigureMMap(context.Context, *memmap.MMapOpts) error
-
-	// Type returns the file type, e.g. linux.S_IFREG.
-	Type(context.Context) (linux.FileMode, error)
-
-	// IncRef increments reference.
-	IncRef()
-
-	// DecRef decrements reference.
-	DecRef(ctx context.Context)
-}
-
-// Lookup provides a common interface to open files.
-type Lookup interface {
-	// OpenPath opens a file.
-	OpenPath(ctx context.Context, path string, opts vfs.OpenOptions, remainingTraversals *uint, resolveFinal bool) (File, error)
-}

pkg/sentry/fsbridge/vfs.go

@@ -1,142 +0,0 @@
-// Copyright 2020 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fsbridge
-
-import (
-	"io"
-
-	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/fspath"
-	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
-	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/usermem"
-)
-
-// VFSFile implements File interface over vfs.FileDescription.
-//
-// +stateify savable
-type VFSFile struct {
-	file *vfs.FileDescription
-}
-
-var _ File = (*VFSFile)(nil)
-
-// NewVFSFile creates a new File over fs.File.
-func NewVFSFile(file *vfs.FileDescription) File {
-	return &VFSFile{file: file}
-}
-
-// PathnameWithDeleted implements File.
-func (f *VFSFile) PathnameWithDeleted(ctx context.Context) string {
-	root := vfs.RootFromContext(ctx)
-	defer root.DecRef(ctx)
-
-	vfsObj := f.file.VirtualDentry().Mount().Filesystem().VirtualFilesystem()
-	name, _ := vfsObj.PathnameWithDeleted(ctx, root, f.file.VirtualDentry())
-	return name
-}
-
-// ReadFull implements File.
-func (f *VFSFile) ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	var total int64
-	for dst.NumBytes() > 0 {
-		n, err := f.file.PRead(ctx, dst, offset+total, vfs.ReadOptions{})
-		total += n
-		if err == io.EOF && total != 0 {
-			return total, io.ErrUnexpectedEOF
-		} else if err != nil {
-			return total, err
-		}
-		dst = dst.DropFirst64(n)
-	}
-	return total, nil
-}
-
-// ConfigureMMap implements File.
-func (f *VFSFile) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
-	return f.file.ConfigureMMap(ctx, opts)
-}
-
-// Type implements File.
-func (f *VFSFile) Type(ctx context.Context) (linux.FileMode, error) {
-	stat, err := f.file.Stat(ctx, vfs.StatOptions{})
-	if err != nil {
-		return 0, err
-	}
-	return linux.FileMode(stat.Mode).FileType(), nil
-}
-
-// IncRef implements File.
-func (f *VFSFile) IncRef() {
-	f.file.IncRef()
-}
-
-// DecRef implements File.
-func (f *VFSFile) DecRef(ctx context.Context) {
-	f.file.DecRef(ctx)
-}
-
-// FileDescription returns the FileDescription represented by f. It does not
-// take an additional reference on the returned FileDescription.
-func (f *VFSFile) FileDescription() *vfs.FileDescription {
-	return f.file
-}
-
-// fsLookup implements Lookup interface using fs.File.
-//
-// +stateify savable
-type vfsLookup struct {
-	mntns *vfs.MountNamespace
-
-	root       vfs.VirtualDentry
-	workingDir vfs.VirtualDentry
-}
-
-var _ Lookup = (*vfsLookup)(nil)
-
-// NewVFSLookup creates a new Lookup.
-func NewVFSLookup(mntns *vfs.MountNamespace, root, workingDir vfs.VirtualDentry) Lookup {
-	return &vfsLookup{
-		mntns:      mntns,
-		root:       root,
-		workingDir: workingDir,
-	}
-}
-
-// OpenPath implements Lookup.
-//
-// remainingTraversals is not configurable, all callers are using the
-// default anyways.
-func (l *vfsLookup) OpenPath(ctx context.Context, pathname string, opts vfs.OpenOptions, _ *uint, resolveFinal bool) (File, error) {
-	vfsObj := l.root.Mount().Filesystem().VirtualFilesystem()
-	creds := auth.CredentialsFromContext(ctx)
-	path := fspath.Parse(pathname)
-	pop := &vfs.PathOperation{
-		Root:               l.root,
-		Start:              l.workingDir,
-		Path:               path,
-		FollowFinalSymlink: resolveFinal,
-	}
-	if path.Absolute {
-		pop.Start = l.root
-	}
-	fd, err := vfsObj.OpenAt(ctx, creds, pop, &opts)
-	if err != nil {
-		return nil, err
-	}
-	return &VFSFile{file: fd}, nil
-}

pkg/sentry/fsimpl/proc/BUILD

@@ -87,7 +87,6 @@ go_library(
         "//pkg/log",
         "//pkg/refs",
         "//pkg/safemem",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/kernfs",
         "//pkg/sentry/fsimpl/lock",
         "//pkg/sentry/inet",

pkg/sentry/fsimpl/proc/task_files.go

@@ -24,7 +24,6 @@ import (
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/safemem"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
@@ -967,7 +966,7 @@ func (s *exeSymlink) Getlink(ctx context.Context, _ *vfs.Mount) (vfs.VirtualDent
 	}
 	defer exec.DecRef(ctx)
 
-	vd := exec.(*fsbridge.VFSFile).FileDescription().VirtualDentry()
+	vd := exec.VirtualDentry()
 	vd.IncRef()
 	return vd, "", nil
 }

pkg/sentry/fsimpl/testutil/BUILD

@@ -17,7 +17,6 @@ go_library(
         "//pkg/fspath",
         "//pkg/hostarch",
         "//pkg/memutil",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/tmpfs",
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",

pkg/sentry/fsimpl/testutil/kernel.go

@@ -25,7 +25,6 @@ import (
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/memutil"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
@@ -128,7 +127,7 @@ func CreateTask(ctx context.Context, name string, tc *kernel.ThreadGroup, mntns
 		return nil, err
 	}
 	m := mm.NewMemoryManager(k, k, k.SleepForAddressSpaceActivation)
-	m.SetExecutable(ctx, fsbridge.NewVFSFile(exe))
+	m.SetExecutable(ctx, exe)
 
 	creds := auth.CredentialsFromContext(ctx)
 	config := &kernel.TaskConfig{

pkg/sentry/kernel/BUILD

@@ -306,7 +306,6 @@ go_library(
         "//pkg/secio",
         "//pkg/sentry/arch",
         "//pkg/sentry/device",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/kernfs",
         "//pkg/sentry/fsimpl/lock",
         "//pkg/sentry/fsimpl/mqfs",

pkg/sentry/kernel/kernel.go

@@ -47,7 +47,6 @@ import (
 	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/pipefs"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/sockfs"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/timerfd"
@@ -660,7 +659,7 @@ type CreateProcessArgs struct {
 	// File is a passed host FD pointing to a file to load as the init binary.
 	//
 	// This is checked if and only if Filename is "".
-	File fsbridge.File
+	File *vfs.FileDescription
 
 	// Argvv is a list of arguments.
 	Argv []string
@@ -839,7 +838,6 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
 		}
 		defer wd.DecRef(ctx)
 	}
-	opener := fsbridge.NewVFSLookup(mntns, root, wd)
 	fsContext := NewFSContext(root, wd, args.Umask)
 
 	tg := k.NewThreadGroup(args.PIDNamespace, NewSignalHandlers(), linux.SIGCHLD, args.Limits)
@@ -856,7 +854,7 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
 		args.File = nil
 	case args.File != nil:
 		// If File is set, take the File provided directly.
-		args.Filename = args.File.PathnameWithDeleted(ctx)
+		args.Filename = args.File.MappedName(ctx)
 	default:
 		// Otherwise look at Argv and see if the first argument is a valid path.
 		if len(args.Argv) == 0 {
@@ -871,7 +869,8 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
 	// Create a fresh task context.
 	remainingTraversals := args.MaxSymlinkTraversals
 	loadArgs := loader.LoadArgs{
-		Opener:              opener,
+		Root:                root,
+		WorkingDir:          wd,
 		RemainingTraversals: &remainingTraversals,
 		ResolveFinal:        true,
 		Filename:            args.Filename,

pkg/sentry/kernel/task_exec.go

@@ -67,7 +67,6 @@ package kernel
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
 	"gvisor.dev/gvisor/pkg/sentry/seccheck"
 	pb "gvisor.dev/gvisor/pkg/sentry/seccheck/points/points_go_proto"
@@ -92,7 +91,7 @@ func (*execStop) Killable() bool { return true }
 //
 // Preconditions: The caller must be running Task.doSyscallInvoke on the task
 // goroutine.
-func (t *Task) Execve(newImage *TaskImage, argv, env []string, executable fsbridge.File, pathname string) (*SyscallControl, error) {
+func (t *Task) Execve(newImage *TaskImage, argv, env []string, executable *vfs.FileDescription, pathname string) (*SyscallControl, error) {
 	// We can't clearly hold kernel package locks while stat'ing executable.
 	if seccheck.Global.Enabled(seccheck.PointExecve) {
 		mask, info := getExecveSeccheckInfo(t, argv, env, executable, pathname)
@@ -303,7 +302,7 @@ func (t *Task) promoteLocked() {
 	oldLeader.exitNotifyLocked(false)
 }
 
-func getExecveSeccheckInfo(t *Task, argv, env []string, executable fsbridge.File, pathname string) (seccheck.FieldSet, *pb.ExecveInfo) {
+func getExecveSeccheckInfo(t *Task, argv, env []string, executable *vfs.FileDescription, pathname string) (seccheck.FieldSet, *pb.ExecveInfo) {
 	fields := seccheck.Global.GetFieldSet(seccheck.PointExecve)
 	info := &pb.ExecveInfo{
 		Argv: argv,
@@ -311,21 +310,19 @@ func getExecveSeccheckInfo(t *Task, argv, env []string, executable fsbridge.File
 	}
 	if executable != nil {
 		info.BinaryPath = pathname
-		if vfs2bridgeFile, ok := executable.(*fsbridge.VFSFile); ok {
-			if fields.Local.Contains(seccheck.FieldSentryExecveBinaryInfo) {
-				statOpts := vfs.StatOptions{
-					Mask: linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID,
+		if fields.Local.Contains(seccheck.FieldSentryExecveBinaryInfo) {
+			statOpts := vfs.StatOptions{
+				Mask: linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID,
+			}
+			if stat, err := executable.Stat(t, statOpts); err == nil {
+				if stat.Mask&(linux.STATX_TYPE|linux.STATX_MODE) == (linux.STATX_TYPE | linux.STATX_MODE) {
+					info.BinaryMode = uint32(stat.Mode)
 				}
-				if stat, err := vfs2bridgeFile.FileDescription().Stat(t, statOpts); err == nil {
-					if stat.Mask&(linux.STATX_TYPE|linux.STATX_MODE) == (linux.STATX_TYPE | linux.STATX_MODE) {
-						info.BinaryMode = uint32(stat.Mode)
-					}
-					if stat.Mask&linux.STATX_UID != 0 {
-						info.BinaryUid = stat.UID
-					}
-					if stat.Mask&linux.STATX_GID != 0 {
-						info.BinaryGid = stat.GID
-					}
+				if stat.Mask&linux.STATX_UID != 0 {
+					info.BinaryUid = stat.UID
+				}
+				if stat.Mask&linux.STATX_GID != 0 {
+					info.BinaryGid = stat.GID
 				}
 			}
 		}

pkg/sentry/kernel/task_log.go

@@ -253,6 +253,6 @@ func (t *Task) traceExecEvent(image *TaskImage) {
 
 	// traceExecEvent function may be called before the task goroutine
 	// starts, so we must use the async context.
-	name := file.PathnameWithDeleted(t.AsyncContext())
+	name := file.MappedName(t.AsyncContext())
 	trace.Logf(t.traceContext, traceCategory, "exec: %s", name)
 }

pkg/sentry/loader/BUILD

@@ -21,12 +21,12 @@ go_library(
         "//pkg/context",
         "//pkg/cpuid",
         "//pkg/errors/linuxerr",
+        "//pkg/fspath",
         "//pkg/hostarch",
         "//pkg/log",
         "//pkg/rand",
         "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/limits",
         "//pkg/sentry/loader/vdsodata",

pkg/sentry/loader/elf.go

@@ -28,10 +28,10 @@ import (
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -238,7 +238,7 @@ func parseHeader(ctx context.Context, f fullReader) (elfInfo, error) {
 
 // mapSegment maps a phdr into the Task. offset is the offset to apply to
 // phdr.Vaddr.
-func mapSegment(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, phdr *elf.ProgHeader, offset hostarch.Addr) error {
+func mapSegment(ctx context.Context, m *mm.MemoryManager, fd *vfs.FileDescription, phdr *elf.ProgHeader, offset hostarch.Addr) error {
 	// We must make a page-aligned mapping.
 	adjust := hostarch.Addr(phdr.Vaddr).PageOffset()
 
@@ -286,7 +286,7 @@ func mapSegment(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, phdr
 				mopts.MappingIdentity.DecRef(ctx)
 			}
 		}()
-		if err := f.ConfigureMMap(ctx, &mopts); err != nil {
+		if err := fd.ConfigureMMap(ctx, &mopts); err != nil {
 			ctx.Infof("File is not memory-mappable: %v", err)
 			return err
 		}
@@ -405,7 +405,7 @@ type loadedELF struct {
 // It does not load the ELF interpreter, or return any auxv entries.
 //
 // Preconditions: f is an ELF file.
-func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, info elfInfo, sharedLoadOffset hostarch.Addr) (loadedELF, error) {
+func loadParsedELF(ctx context.Context, m *mm.MemoryManager, fd *vfs.FileDescription, info elfInfo, sharedLoadOffset hostarch.Addr) (loadedELF, error) {
 	first := true
 	var start, end hostarch.Addr
 	var interpreter string
@@ -445,7 +445,7 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, in
 			}
 
 			path := make([]byte, phdr.Filesz)
-			_, err := f.ReadFull(ctx, usermem.BytesIOSequence(path), int64(phdr.Off))
+			_, err := fd.ReadFull(ctx, usermem.BytesIOSequence(path), int64(phdr.Off))
 			if err != nil {
 				// If an interpreter was specified, it should exist.
 				ctx.Infof("Error reading PT_INTERP path: %v", err)
@@ -542,7 +542,7 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, in
 				continue
 			}
 
-			if err := mapSegment(ctx, m, f, &phdr, offset); err != nil {
+			if err := mapSegment(ctx, m, fd, &phdr, offset); err != nil {
 				ctx.Infof("Failed to map PT_LOAD segment: %+v", phdr)
 				return loadedELF{}, err
 			}
@@ -580,8 +580,8 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, in
 // Preconditions:
 //   - f is an ELF file.
 //   - f is the first ELF loaded into m.
-func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs cpuid.FeatureSet, f fsbridge.File) (loadedELF, *arch.Context64, error) {
-	info, err := parseHeader(ctx, f)
+func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs cpuid.FeatureSet, fd *vfs.FileDescription) (loadedELF, *arch.Context64, error) {
+	info, err := parseHeader(ctx, fd)
 	if err != nil {
 		ctx.Infof("Failed to parse initial ELF: %v", err)
 		return loadedELF{}, nil, err
@@ -606,7 +606,7 @@ func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs cpuid.FeatureSe
 	// PIELoadAddress tries to move the ELF out of the way of the default
 	// mmap base to ensure that the initial brk has sufficient space to
 	// grow.
-	le, err := loadParsedELF(ctx, m, f, info, ac.PIELoadAddress(l))
+	le, err := loadParsedELF(ctx, m, fd, info, ac.PIELoadAddress(l))
 	return le, ac, err
 }
 
@@ -617,8 +617,8 @@ func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs cpuid.FeatureSe
 // It does not return any auxv entries.
 //
 // Preconditions: f is an ELF file.
-func loadInterpreterELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, initial loadedELF) (loadedELF, error) {
-	info, err := parseHeader(ctx, f)
+func loadInterpreterELF(ctx context.Context, m *mm.MemoryManager, fd *vfs.FileDescription, initial loadedELF) (loadedELF, error) {
+	info, err := parseHeader(ctx, fd)
 	if err != nil {
 		if linuxerr.Equals(linuxerr.ENOEXEC, err) {
 			// Bad interpreter.
@@ -638,7 +638,7 @@ func loadInterpreterELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.Fil
 
 	// The interpreter is not given a load offset, as its location does not
 	// affect brk.
-	return loadParsedELF(ctx, m, f, info, 0)
+	return loadParsedELF(ctx, m, fd, info, 0)
 }
 
 // loadELF loads args.File into the Task address space.

pkg/sentry/loader/interpreter.go

@@ -20,7 +20,7 @@ import (
 
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -37,9 +37,9 @@ const (
 )
 
 // parseInterpreterScript returns the interpreter path and argv.
-func parseInterpreterScript(ctx context.Context, filename string, f fsbridge.File, argv []string) (newpath string, newargv []string, err error) {
+func parseInterpreterScript(ctx context.Context, filename string, fd *vfs.FileDescription, argv []string) (newpath string, newargv []string, err error) {
 	line := make([]byte, interpMaxLineLength)
-	n, err := f.ReadFull(ctx, usermem.BytesIOSequence(line), 0)
+	n, err := fd.ReadFull(ctx, usermem.BytesIOSequence(line), 0)
 	// Short read is OK.
 	if err != nil && err != io.ErrUnexpectedEOF {
 		if err == io.EOF {

pkg/sentry/loader/loader.go

@@ -27,10 +27,10 @@ import (
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
+	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
@@ -55,18 +55,21 @@ type LoadArgs struct {
 	// Filename is the path for the executable.
 	Filename string
 
-	// File is an open fs.File object of the executable. If File is not
-	// nil, then File will be loaded and Filename will be ignored.
+	// File is an open FD of the executable. If File is not nil, then File will
+	// be loaded and Filename will be ignored.
 	//
 	// The caller is responsible for checking that the user can execute this file.
-	File fsbridge.File
+	File *vfs.FileDescription
 
-	// Opener is used to open the executable file when 'File' is nil.
-	Opener fsbridge.Lookup
+	// Root is the current filesystem root.
+	Root vfs.VirtualDentry
+
+	// WorkingDir is the current working directory.
+	WorkingDir vfs.VirtualDentry
 
 	// If AfterOpen is not nil, it is called after every successful call to
 	// Opener.OpenPath().
-	AfterOpen func(f fsbridge.File)
+	AfterOpen func(f *vfs.FileDescription)
 
 	// CloseOnExec indicates that the executable (or one of its parent
 	// directories) was opened with O_CLOEXEC. If the executable is an
@@ -91,7 +94,7 @@ type LoadArgs struct {
 // installed in the Task FDTable. The caller takes ownership of both.
 //
 // args.Filename must be a readable, executable, regular file.
-func openPath(ctx context.Context, args LoadArgs) (fsbridge.File, error) {
+func openPath(ctx context.Context, args LoadArgs) (*vfs.FileDescription, error) {
 	if args.Filename == "" {
 		ctx.Infof("cannot open empty name")
 		return nil, linuxerr.ENOENT
@@ -106,23 +109,35 @@ func openPath(ctx context.Context, args LoadArgs) (fsbridge.File, error) {
 		Flags:    linux.O_RDONLY,
 		FileExec: true,
 	}
-	f, err := args.Opener.OpenPath(ctx, args.Filename, opts, args.RemainingTraversals, args.ResolveFinal)
+	vfsObj := args.Root.Mount().Filesystem().VirtualFilesystem()
+	creds := auth.CredentialsFromContext(ctx)
+	path := fspath.Parse(args.Filename)
+	pop := &vfs.PathOperation{
+		Root:               args.Root,
+		Start:              args.WorkingDir,
+		Path:               path,
+		FollowFinalSymlink: args.ResolveFinal,
+	}
+	if path.Absolute {
+		pop.Start = args.Root
+	}
+	fd, err := vfsObj.OpenAt(ctx, creds, pop, &opts)
 	if err != nil {
-		return f, err
+		return nil, err
 	}
 	if args.AfterOpen != nil {
-		args.AfterOpen(f)
+		args.AfterOpen(fd)
 	}
-	return f, nil
+	return fd, nil
 }
 
 // checkIsRegularFile prevents us from trying to execute a directory, pipe, etc.
-func checkIsRegularFile(ctx context.Context, file fsbridge.File, filename string) error {
-	t, err := file.Type(ctx)
+func checkIsRegularFile(ctx context.Context, fd *vfs.FileDescription, filename string) error {
+	stat, err := fd.Stat(ctx, vfs.StatOptions{})
 	if err != nil {
 		return err
 	}
-	if t != linux.ModeRegular {
+	if t := linux.FileMode(stat.Mode).FileType(); t != linux.ModeRegular {
 		ctx.Infof("%q is not a regular file: %v", filename, t)
 		return linuxerr.EACCES
 	}
@@ -157,7 +172,7 @@ const (
 //   - arch.Context64 matching the binary arch
 //   - fs.Dirent of the binary file
 //   - Possibly updated args.Argv
-func loadExecutable(ctx context.Context, args LoadArgs) (loadedELF, *arch.Context64, fsbridge.File, []string, error) {
+func loadExecutable(ctx context.Context, args LoadArgs) (loadedELF, *arch.Context64, *vfs.FileDescription, []string, error) {
 	for i := 0; i < maxLoaderAttempts; i++ {
 		if args.File == nil {
 			var err error

pkg/sentry/mm/BUILD

@@ -182,7 +182,6 @@ go_library(
         "//pkg/safecopy",
         "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/kernel/futex",
         "//pkg/sentry/kernel/shm",
@@ -191,6 +190,7 @@ go_library(
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
         "//pkg/sentry/usage",
+        "//pkg/sentry/vfs",
         "//pkg/sync",
         "//pkg/sync/locking",
         "//pkg/usermem",

pkg/sentry/mm/metadata.go

@@ -18,7 +18,7 @@ import (
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 )
 
 // Dumpability describes if and how core dumps should be created.
@@ -129,7 +129,7 @@ func (mm *MemoryManager) SetAuxv(auxv arch.Auxv) {
 //
 // An additional reference will be taken in the case of a non-nil executable,
 // which must be released by the caller.
-func (mm *MemoryManager) Executable() fsbridge.File {
+func (mm *MemoryManager) Executable() *vfs.FileDescription {
 	mm.metadataMu.Lock()
 	defer mm.metadataMu.Unlock()
 
@@ -144,15 +144,15 @@ func (mm *MemoryManager) Executable() fsbridge.File {
 // SetExecutable sets the executable.
 //
 // This takes a reference on d.
-func (mm *MemoryManager) SetExecutable(ctx context.Context, file fsbridge.File) {
+func (mm *MemoryManager) SetExecutable(ctx context.Context, fd *vfs.FileDescription) {
 	mm.metadataMu.Lock()
 
 	// Grab a new reference.
-	file.IncRef()
+	fd.IncRef()
 
 	// Set the executable.
 	orig := mm.executable
-	mm.executable = file
+	mm.executable = fd
 
 	mm.metadataMu.Unlock()
 

pkg/sentry/mm/mm.go

@@ -44,10 +44,10 @@ import (
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 )
 
 // MapsCallbackFunc has all the parameters required for populating an entry of /proc/[pid]/maps.
@@ -226,7 +226,7 @@ type MemoryManager struct {
 	// is not nil, it holds a reference on the Dirent.
 	//
 	// executable is protected by metadataMu.
-	executable fsbridge.File
+	executable *vfs.FileDescription
 
 	// aioManager keeps track of AIOContexts used for async IOs. AIOManager
 	// must be cloned when CLONE_VM is used.

pkg/sentry/syscalls/linux/BUILD

@@ -79,7 +79,6 @@ go_library(
         "//pkg/rand",
         "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/eventfd",
         "//pkg/sentry/fsimpl/host",
         "//pkg/sentry/fsimpl/iouringfs",

pkg/sentry/syscalls/linux/sys_prctl.go

@@ -21,7 +21,6 @@ import (
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/marshal/primitive"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
@@ -141,7 +140,7 @@ func Prctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 			}
 
 			// Set the underlying executable.
-			t.MemoryManager().SetExecutable(t, fsbridge.NewVFSFile(file))
+			t.MemoryManager().SetExecutable(t, file)
 
 		case linux.PR_SET_MM_AUXV,
 			linux.PR_SET_MM_START_CODE,