Merge branch 'master' into ipt-udp-matchers

62 files changed, 370 insertions, 248 deletions

diff --git a/pkg/sentry/kernel/BUILD b/pkg/sentry/kernel/BUILD
index ac85ba0c8..a27628c0a 100644
--- a/pkg/sentry/kernel/BUILD
+++ b/pkg/sentry/kernel/BUILD
@@ -1,8 +1,5 @@
-load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
-load("@rules_cc//cc:defs.bzl", "cc_proto_library")
+load("//tools:defs.bzl", "go_library", "go_test", "proto_library")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -78,26 +75,12 @@ go_template_instance(
 )
 
 proto_library(
-    name = "uncaught_signal_proto",
+    name = "uncaught_signal",
     srcs = ["uncaught_signal.proto"],
     visibility = ["//visibility:public"],
     deps = ["//pkg/sentry/arch:registers_proto"],
 )
 
-cc_proto_library(
-    name = "uncaught_signal_cc_proto",
-    visibility = ["//visibility:public"],
-    deps = [":uncaught_signal_proto"],
-)
-
-go_proto_library(
-    name = "uncaught_signal_go_proto",
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto",
-    proto = ":uncaught_signal_proto",
-    visibility = ["//visibility:public"],
-    deps = ["//pkg/sentry/arch:registers_go_proto"],
-)
-
 go_library(
     name = "kernel",
     srcs = [
@@ -156,7 +139,6 @@ go_library(
         "vdso.go",
         "version.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel",
     imports = [
         "gvisor.dev/gvisor/pkg/bpf",
         "gvisor.dev/gvisor/pkg/sentry/device",
@@ -171,14 +153,15 @@ go_library(
         "//pkg/binary",
         "//pkg/bits",
         "//pkg/bpf",
+        "//pkg/context",
         "//pkg/cpuid",
         "//pkg/eventchannel",
         "//pkg/log",
         "//pkg/metric",
         "//pkg/refs",
+        "//pkg/safemem",
         "//pkg/secio",
         "//pkg/sentry/arch",
-        "//pkg/sentry/context",
         "//pkg/sentry/device",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/lock",
@@ -198,7 +181,6 @@ go_library(
         "//pkg/sentry/mm",
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
-        "//pkg/sentry/safemem",
         "//pkg/sentry/socket/netlink/port",
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/time",
@@ -206,7 +188,7 @@ go_library(
         "//pkg/sentry/unimpl:unimplemented_syscall_go_proto",
         "//pkg/sentry/uniqueid",
         "//pkg/sentry/usage",
-        "//pkg/sentry/usermem",
+        "//pkg/sentry/vfs",
         "//pkg/state",
         "//pkg/state/statefile",
         "//pkg/sync",
@@ -214,6 +196,7 @@ go_library(
         "//pkg/syserror",
         "//pkg/tcpip",
         "//pkg/tcpip/stack",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
@@ -227,12 +210,12 @@ go_test(
         "task_test.go",
         "timekeeper_test.go",
     ],
-    embed = [":kernel"],
+    library = ":kernel",
     deps = [
         "//pkg/abi",
+        "//pkg/context",
         "//pkg/sentry/arch",
-        "//pkg/sentry/context",
-        "//pkg/sentry/context/contexttest",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/filetest",
         "//pkg/sentry/kernel/sched",
@@ -240,8 +223,8 @@ go_test(
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/time",
         "//pkg/sentry/usage",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
     ],
 )
diff --git a/pkg/sentry/kernel/auth/BUILD b/pkg/sentry/kernel/auth/BUILD
index 1aa72fa47..2bc49483a 100644
--- a/pkg/sentry/kernel/auth/BUILD
+++ b/pkg/sentry/kernel/auth/BUILD
@@ -1,5 +1,5 @@
+load("//tools:defs.bzl", "go_library")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -57,13 +57,12 @@ go_library(
         "id_map_set.go",
         "user_namespace.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/auth",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
         "//pkg/bits",
+        "//pkg/context",
         "//pkg/log",
-        "//pkg/sentry/context",
         "//pkg/sync",
         "//pkg/syserror",
     ],
diff --git a/pkg/sentry/kernel/auth/context.go b/pkg/sentry/kernel/auth/context.go
index 5c0e7d6b6..ef5723127 100644
--- a/pkg/sentry/kernel/auth/context.go
+++ b/pkg/sentry/kernel/auth/context.go
@@ -15,7 +15,7 @@
 package auth
 
 import (
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 )
 
 // contextID is the auth package's type for context.Context.Value keys.
diff --git a/pkg/sentry/kernel/auth/id_map.go b/pkg/sentry/kernel/auth/id_map.go
index 3d74bc610..28cbe159d 100644
--- a/pkg/sentry/kernel/auth/id_map.go
+++ b/pkg/sentry/kernel/auth/id_map.go
@@ -16,7 +16,7 @@ package auth
 
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
diff --git a/pkg/sentry/kernel/context.go b/pkg/sentry/kernel/context.go
index 3c9dceaba..0c40bf315 100644
--- a/pkg/sentry/kernel/context.go
+++ b/pkg/sentry/kernel/context.go
@@ -17,8 +17,8 @@ package kernel
 import (
 	"time"
 
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 )
 
 // contextID is the kernel package's type for context.Context.Value keys.
diff --git a/pkg/sentry/kernel/contexttest/BUILD b/pkg/sentry/kernel/contexttest/BUILD
index 3a88a585c..9d26392c0 100644
--- a/pkg/sentry/kernel/contexttest/BUILD
+++ b/pkg/sentry/kernel/contexttest/BUILD
@@ -1,4 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -6,11 +6,10 @@ go_library(
     name = "contexttest",
     testonly = 1,
     srcs = ["contexttest.go"],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/contexttest",
     visibility = ["//pkg/sentry:internal"],
     deps = [
-        "//pkg/sentry/context",
-        "//pkg/sentry/context/contexttest",
+        "//pkg/context",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/kernel",
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
diff --git a/pkg/sentry/kernel/contexttest/contexttest.go b/pkg/sentry/kernel/contexttest/contexttest.go
index 82f9d8922..22c340e56 100644
--- a/pkg/sentry/kernel/contexttest/contexttest.go
+++ b/pkg/sentry/kernel/contexttest/contexttest.go
@@ -19,8 +19,8 @@ package contexttest
 import (
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
diff --git a/pkg/sentry/kernel/epoll/BUILD b/pkg/sentry/kernel/epoll/BUILD
index c47f6b6fc..dedf0fa15 100644
--- a/pkg/sentry/kernel/epoll/BUILD
+++ b/pkg/sentry/kernel/epoll/BUILD
@@ -1,6 +1,5 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -23,16 +22,15 @@ go_library(
         "epoll_list.go",
         "epoll_state.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/epoll",
     visibility = ["//pkg/sentry:internal"],
     deps = [
+        "//pkg/context",
         "//pkg/refs",
-        "//pkg/sentry/context",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/anon",
         "//pkg/sentry/fs/fsutil",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
@@ -43,9 +41,9 @@ go_test(
     srcs = [
         "epoll_test.go",
     ],
-    embed = [":epoll"],
+    library = ":epoll",
     deps = [
-        "//pkg/sentry/context/contexttest",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/fs/filetest",
         "//pkg/waiter",
     ],
diff --git a/pkg/sentry/kernel/epoll/epoll.go b/pkg/sentry/kernel/epoll/epoll.go
index e84742993..8bffb78fc 100644
--- a/pkg/sentry/kernel/epoll/epoll.go
+++ b/pkg/sentry/kernel/epoll/epoll.go
@@ -20,13 +20,13 @@ import (
 	"fmt"
 	"syscall"
 
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/refs"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/anon"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/epoll/epoll_test.go b/pkg/sentry/kernel/epoll/epoll_test.go
index 4a20d4c82..22630e9c5 100644
--- a/pkg/sentry/kernel/epoll/epoll_test.go
+++ b/pkg/sentry/kernel/epoll/epoll_test.go
@@ -17,7 +17,7 @@ package epoll
 import (
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/fs/filetest"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
diff --git a/pkg/sentry/kernel/eventfd/BUILD b/pkg/sentry/kernel/eventfd/BUILD
index c831fbab2..9983a32e5 100644
--- a/pkg/sentry/kernel/eventfd/BUILD
+++ b/pkg/sentry/kernel/eventfd/BUILD
@@ -1,23 +1,21 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library", "go_test")
 
 package(licenses = ["notice"])
 
 go_library(
     name = "eventfd",
     srcs = ["eventfd.go"],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/eventfd",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/context",
         "//pkg/fdnotifier",
-        "//pkg/sentry/context",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/anon",
         "//pkg/sentry/fs/fsutil",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
@@ -26,10 +24,10 @@ go_test(
     name = "eventfd_test",
     size = "small",
     srcs = ["eventfd_test.go"],
-    embed = [":eventfd"],
+    library = ":eventfd",
     deps = [
-        "//pkg/sentry/context/contexttest",
-        "//pkg/sentry/usermem",
+        "//pkg/sentry/contexttest",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
diff --git a/pkg/sentry/kernel/eventfd/eventfd.go b/pkg/sentry/kernel/eventfd/eventfd.go
index 687690679..87951adeb 100644
--- a/pkg/sentry/kernel/eventfd/eventfd.go
+++ b/pkg/sentry/kernel/eventfd/eventfd.go
@@ -21,14 +21,14 @@ import (
 	"syscall"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/fdnotifier"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/anon"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/eventfd/eventfd_test.go b/pkg/sentry/kernel/eventfd/eventfd_test.go
index 018c7f3ef..9b4892f74 100644
--- a/pkg/sentry/kernel/eventfd/eventfd_test.go
+++ b/pkg/sentry/kernel/eventfd/eventfd_test.go
@@ -17,8 +17,8 @@ package eventfd
 import (
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/fasync/BUILD b/pkg/sentry/kernel/fasync/BUILD
index 6b36bc63e..b9126e946 100644
--- a/pkg/sentry/kernel/fasync/BUILD
+++ b/pkg/sentry/kernel/fasync/BUILD
@@ -1,11 +1,10 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
 go_library(
     name = "fasync",
     srcs = ["fasync.go"],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/fasync",
     visibility = ["//:sandbox"],
     deps = [
         "//pkg/abi/linux",
diff --git a/pkg/sentry/kernel/fd_table.go b/pkg/sentry/kernel/fd_table.go
index cd1501f85..23b88f7a6 100644
--- a/pkg/sentry/kernel/fd_table.go
+++ b/pkg/sentry/kernel/fd_table.go
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2018 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.
@@ -15,18 +15,19 @@
 package kernel
 
 import (
-	"bytes"
 	"fmt"
 	"math"
+	"strings"
 	"sync/atomic"
 	"syscall"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/refs"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/sync"
 )
 
@@ -62,10 +63,14 @@ func (f FDFlags) ToLinuxFDFlags() (mask uint) {
 // Note that this is immutable and can only be changed via operations on the
 // descriptorTable.
 //
+// It contains both VFS1 and VFS2 file types, but only one of them can be set.
+//
 // +stateify savable
 type descriptor struct {
-	file  *fs.File
-	flags FDFlags
+	// TODO(gvisor.dev/issue/1624): Remove fs.File.
+	file     *fs.File
+	fileVFS2 *vfs.FileDescription
+	flags    FDFlags
 }
 
 // FDTable is used to manage File references and flags.
@@ -95,10 +100,11 @@ type FDTable struct {
 
 func (f *FDTable) saveDescriptorTable() map[int32]descriptor {
 	m := make(map[int32]descriptor)
-	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
+	f.forEach(func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
 		m[fd] = descriptor{
-			file:  file,
-			flags: flags,
+			file:     file,
+			fileVFS2: fileVFS2,
+			flags:    flags,
 		}
 	})
 	return m
@@ -107,13 +113,17 @@ func (f *FDTable) saveDescriptorTable() map[int32]descriptor {
 func (f *FDTable) loadDescriptorTable(m map[int32]descriptor) {
 	f.init() // Initialize table.
 	for fd, d := range m {
-		f.set(fd, d.file, d.flags)
-
-		// Note that we do _not_ need to acquire a extra table
-		// reference here. The table reference will already be
-		// accounted for in the file, so we drop the reference taken by
-		// set above.
-		d.file.DecRef()
+		f.setAll(fd, d.file, d.fileVFS2, d.flags)
+
+		// Note that we do _not_ need to acquire a extra table reference here. The
+		// table reference will already be accounted for in the file, so we drop the
+		// reference taken by set above.
+		switch {
+		case d.file != nil:
+			d.file.DecRef()
+		case d.fileVFS2 != nil:
+			d.fileVFS2.DecRef()
+		}
 	}
 }
 
@@ -139,6 +149,15 @@ func (f *FDTable) drop(file *fs.File) {
 	file.DecRef()
 }
 
+// dropVFS2 drops the table reference.
+func (f *FDTable) dropVFS2(file *vfs.FileDescription) {
+	// TODO(gvisor.dev/issue/1480): Release locks.
+	// TODO(gvisor.dev/issue/1479): Send inotify events.
+
+	// Drop the table reference.
+	file.DecRef()
+}
+
 // ID returns a unique identifier for this FDTable.
 func (f *FDTable) ID() uint64 {
 	return f.uid
@@ -156,7 +175,7 @@ func (k *Kernel) NewFDTable() *FDTable {
 
 // destroy removes all of the file descriptors from the map.
 func (f *FDTable) destroy() {
-	f.RemoveIf(func(*fs.File, FDFlags) bool {
+	f.RemoveIf(func(*fs.File, *vfs.FileDescription, FDFlags) bool {
 		return true
 	})
 }
@@ -175,19 +194,26 @@ func (f *FDTable) Size() int {
 // forEach iterates over all non-nil files.
 //
 // It is the caller's responsibility to acquire an appropriate lock.
-func (f *FDTable) forEach(fn func(fd int32, file *fs.File, flags FDFlags)) {
+func (f *FDTable) forEach(fn func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags)) {
 	fd := int32(0)
 	for {
-		file, flags, ok := f.get(fd)
+		file, fileVFS2, flags, ok := f.getAll(fd)
 		if !ok {
 			break
 		}
-		if file != nil {
+		switch {
+		case file != nil:
 			if !file.TryIncRef() {
 				continue // Race caught.
 			}
-			fn(int32(fd), file, flags)
+			fn(fd, file, nil, flags)
 			file.DecRef()
+		case fileVFS2 != nil:
+			if !fileVFS2.TryIncRef() {
+				continue // Race caught.
+			}
+			fn(fd, nil, fileVFS2, flags)
+			fileVFS2.DecRef()
 		}
 		fd++
 	}
@@ -195,12 +221,24 @@ func (f *FDTable) forEach(fn func(fd int32, file *fs.File, flags FDFlags)) {
 
 // String is a stringer for FDTable.
 func (f *FDTable) String() string {
-	var b bytes.Buffer
-	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
-		n, _ := file.Dirent.FullName(nil /* root */)
-		b.WriteString(fmt.Sprintf("\tfd:%d => name %s\n", fd, n))
+	var buf strings.Builder
+	f.forEach(func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
+		switch {
+		case file != nil:
+			n, _ := file.Dirent.FullName(nil /* root */)
+			fmt.Fprintf(&buf, "\tfd:%d => name %s\n", fd, n)
+
+		case fileVFS2 != nil:
+			vfsObj := fileVFS2.Mount().Filesystem().VirtualFilesystem()
+			name, err := vfsObj.PathnameWithDeleted(context.Background(), vfs.VirtualDentry{}, fileVFS2.VirtualDentry())
+			if err != nil {
+				fmt.Fprintf(&buf, "<err: %v>\n", err)
+				return
+			}
+			fmt.Fprintf(&buf, "\tfd:%d => name %s\n", fd, name)
+		}
 	})
-	return b.String()
+	return buf.String()
 }
 
 // NewFDs allocates new FDs guaranteed to be the lowest number available
@@ -262,6 +300,17 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags
 // reference for that FD, the ref count for that existing reference is
 // decremented.
 func (f *FDTable) NewFDAt(ctx context.Context, fd int32, file *fs.File, flags FDFlags) error {
+	return f.newFDAt(ctx, fd, file, nil, flags)
+}
+
+// NewFDAtVFS2 sets the file reference for the given FD. If there is an active
+// reference for that FD, the ref count for that existing reference is
+// decremented.
+func (f *FDTable) NewFDAtVFS2(ctx context.Context, fd int32, file *vfs.FileDescription, flags FDFlags) error {
+	return f.newFDAt(ctx, fd, nil, file, flags)
+}
+
+func (f *FDTable) newFDAt(ctx context.Context, fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) error {
 	if fd < 0 {
 		// Don't accept negative FDs.
 		return syscall.EBADF
@@ -278,7 +327,7 @@ func (f *FDTable) NewFDAt(ctx context.Context, fd int32, file *fs.File, flags FD
 	}
 
 	// Install the entry.
-	f.set(fd, file, flags)
+	f.setAll(fd, file, fileVFS2, flags)
 	return nil
 }
 
@@ -330,10 +379,35 @@ func (f *FDTable) Get(fd int32) (*fs.File, FDFlags) {
 	}
 }
 
+// GetVFS2 returns a reference to the file and the flags for the FD or nil if no
+// file is defined for the given fd.
+//
+// N.B. Callers are required to use DecRef when they are done.
+//
+//go:nosplit
+func (f *FDTable) GetVFS2(fd int32) (*vfs.FileDescription, FDFlags) {
+	if fd < 0 {
+		return nil, FDFlags{}
+	}
+
+	for {
+		file, flags, _ := f.getVFS2(fd)
+		if file != nil {
+			if !file.TryIncRef() {
+				continue // Race caught.
+			}
+			// Reference acquired.
+			return file, flags
+		}
+		// No file available.
+		return nil, FDFlags{}
+	}
+}
+
 // GetFDs returns a list of valid fds.
 func (f *FDTable) GetFDs() []int32 {
 	fds := make([]int32, 0, int(atomic.LoadInt32(&f.used)))
-	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
+	f.forEach(func(fd int32, _ *fs.File, _ *vfs.FileDescription, _ FDFlags) {
 		fds = append(fds, fd)
 	})
 	return fds
@@ -344,7 +418,19 @@ func (f *FDTable) GetFDs() []int32 {
 // they're done using the slice.
 func (f *FDTable) GetRefs() []*fs.File {
 	files := make([]*fs.File, 0, f.Size())
-	f.forEach(func(_ int32, file *fs.File, flags FDFlags) {
+	f.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
+		file.IncRef() // Acquire a reference for caller.
+		files = append(files, file)
+	})
+	return files
+}
+
+// GetRefsVFS2 returns a stable slice of references to all files and bumps the
+// reference count on each. The caller must use DecRef on each reference when
+// they're done using the slice.
+func (f *FDTable) GetRefsVFS2() []*vfs.FileDescription {
+	files := make([]*vfs.FileDescription, 0, f.Size())
+	f.forEach(func(_ int32, _ *fs.File, file *vfs.FileDescription, _ FDFlags) {
 		file.IncRef() // Acquire a reference for caller.
 		files = append(files, file)
 	})
@@ -355,10 +441,15 @@ func (f *FDTable) GetRefs() []*fs.File {
 func (f *FDTable) Fork() *FDTable {
 	clone := f.k.NewFDTable()
 
-	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
+	f.forEach(func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
 		// The set function here will acquire an appropriate table
 		// reference for the clone. We don't need anything else.
-		clone.set(fd, file, flags)
+		switch {
+		case file != nil:
+			clone.set(fd, file, flags)
+		case fileVFS2 != nil:
+			clone.setVFS2(fd, fileVFS2, flags)
+		}
 	})
 	return clone
 }
@@ -366,9 +457,9 @@ func (f *FDTable) Fork() *FDTable {
 // Remove removes an FD from and returns a non-file iff successful.
 //
 // N.B. Callers are required to use DecRef when they are done.
-func (f *FDTable) Remove(fd int32) *fs.File {
+func (f *FDTable) Remove(fd int32) (*fs.File, *vfs.FileDescription) {
 	if fd < 0 {
-		return nil
+		return nil, nil
 	}
 
 	f.mu.Lock()
@@ -379,21 +470,26 @@ func (f *FDTable) Remove(fd int32) *fs.File {
 		f.next = fd
 	}
 
-	orig, _, _ := f.get(fd)
-	if orig != nil {
-		orig.IncRef()             // Reference for caller.
-		f.set(fd, nil, FDFlags{}) // Zap entry.
+	orig, orig2, _, _ := f.getAll(fd)
+
+	// Add reference for caller.
+	switch {
+	case orig != nil:
+		orig.IncRef()
+	case orig2 != nil:
+		orig2.IncRef()
 	}
-	return orig
+	f.setAll(fd, nil, nil, FDFlags{}) // Zap entry.
+	return orig, orig2
 }
 
 // RemoveIf removes all FDs where cond is true.
-func (f *FDTable) RemoveIf(cond func(*fs.File, FDFlags) bool) {
+func (f *FDTable) RemoveIf(cond func(*fs.File, *vfs.FileDescription, FDFlags) bool) {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
-	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
-		if cond(file, flags) {
+	f.forEach(func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
+		if cond(file, fileVFS2, flags) {
 			f.set(fd, nil, FDFlags{}) // Clear from table.
 			// Update current available position.
 			if fd < f.next {
diff --git a/pkg/sentry/kernel/fd_table_test.go b/pkg/sentry/kernel/fd_table_test.go
index eccb7d1e7..29f95a2c4 100644
--- a/pkg/sentry/kernel/fd_table_test.go
+++ b/pkg/sentry/kernel/fd_table_test.go
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2018 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.
@@ -18,8 +18,8 @@ import (
 	"runtime"
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/filetest"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
@@ -150,13 +150,13 @@ func TestFDTable(t *testing.T) {
 			t.Fatalf("fdTable.Get(2): got a %v, wanted nil", ref)
 		}
 
-		ref := fdTable.Remove(1)
+		ref, _ := fdTable.Remove(1)
 		if ref == nil {
 			t.Fatalf("fdTable.Remove(1) for an existing FD: failed, want success")
 		}
 		ref.DecRef()
 
-		if ref := fdTable.Remove(1); ref != nil {
+		if ref, _ := fdTable.Remove(1); ref != nil {
 			t.Fatalf("r.Remove(1) for a removed FD: got success, want failure")
 		}
 	})
diff --git a/pkg/sentry/kernel/fd_table_unsafe.go b/pkg/sentry/kernel/fd_table_unsafe.go
index e009df974..7fd97dc53 100644
--- a/pkg/sentry/kernel/fd_table_unsafe.go
+++ b/pkg/sentry/kernel/fd_table_unsafe.go
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2018 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.
@@ -19,6 +19,7 @@ import (
 	"unsafe"
 
 	"gvisor.dev/gvisor/pkg/sentry/fs"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 )
 
 type descriptorTable struct {
@@ -41,15 +42,38 @@ func (f *FDTable) init() {
 //
 //go:nosplit
 func (f *FDTable) get(fd int32) (*fs.File, FDFlags, bool) {
+	file, _, flags, ok := f.getAll(fd)
+	return file, flags, ok
+}
+
+// getVFS2 gets a file entry.
+//
+// The boolean indicates whether this was in range.
+//
+//go:nosplit
+func (f *FDTable) getVFS2(fd int32) (*vfs.FileDescription, FDFlags, bool) {
+	_, file, flags, ok := f.getAll(fd)
+	return file, flags, ok
+}
+
+// getAll gets a file entry.
+//
+// The boolean indicates whether this was in range.
+//
+//go:nosplit
+func (f *FDTable) getAll(fd int32) (*fs.File, *vfs.FileDescription, FDFlags, bool) {
 	slice := *(*[]unsafe.Pointer)(atomic.LoadPointer(&f.slice))
 	if fd >= int32(len(slice)) {
-		return nil, FDFlags{}, false
+		return nil, nil, FDFlags{}, false
 	}
 	d := (*descriptor)(atomic.LoadPointer(&slice[fd]))
 	if d == nil {
-		return nil, FDFlags{}, true
+		return nil, nil, FDFlags{}, true
 	}
-	return d.file, d.flags, true
+	if d.file != nil && d.fileVFS2 != nil {
+		panic("VFS1 and VFS2 files set")
+	}
+	return d.file, d.fileVFS2, d.flags, true
 }
 
 // set sets an entry.
@@ -59,6 +83,30 @@ func (f *FDTable) get(fd int32) (*fs.File, FDFlags, bool) {
 //
 // Precondition: mu must be held.
 func (f *FDTable) set(fd int32, file *fs.File, flags FDFlags) {
+	f.setAll(fd, file, nil, flags)
+}
+
+// setVFS2 sets an entry.
+//
+// This handles accounting changes, as well as acquiring and releasing the
+// reference needed by the table iff the file is different.
+//
+// Precondition: mu must be held.
+func (f *FDTable) setVFS2(fd int32, file *vfs.FileDescription, flags FDFlags) {
+	f.setAll(fd, nil, file, flags)
+}
+
+// setAll sets an entry.
+//
+// This handles accounting changes, as well as acquiring and releasing the
+// reference needed by the table iff the file is different.
+//
+// Precondition: mu must be held.
+func (f *FDTable) setAll(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
+	if file != nil && fileVFS2 != nil {
+		panic("VFS1 and VFS2 files set")
+	}
+
 	slice := *(*[]unsafe.Pointer)(atomic.LoadPointer(&f.slice))
 
 	// Grow the table as required.
@@ -71,33 +119,51 @@ func (f *FDTable) set(fd int32, file *fs.File, flags FDFlags) {
 		atomic.StorePointer(&f.slice, unsafe.Pointer(&slice))
 	}
 
-	// Create the new element.
-	var d *descriptor
-	if file != nil {
-		d = &descriptor{
-			file:  file,
-			flags: flags,
+	var desc *descriptor
+	if file != nil || fileVFS2 != nil {
+		desc = &descriptor{
+			file:     file,
+			fileVFS2: fileVFS2,
+			flags:    flags,
 		}
 	}
 
 	// Update the single element.
-	orig := (*descriptor)(atomic.SwapPointer(&slice[fd], unsafe.Pointer(d)))
+	orig := (*descriptor)(atomic.SwapPointer(&slice[fd], unsafe.Pointer(desc)))
 
 	// Acquire a table reference.
-	if file != nil && (orig == nil || file != orig.file) {
-		file.IncRef()
+	if desc != nil {
+		switch {
+		case desc.file != nil:
+			if orig == nil || desc.file != orig.file {
+				desc.file.IncRef()
+			}
+		case desc.fileVFS2 != nil:
+			if orig == nil || desc.fileVFS2 != orig.fileVFS2 {
+				desc.fileVFS2.IncRef()
+			}
+		}
 	}
 
 	// Drop the table reference.
-	if orig != nil && file != orig.file {
-		f.drop(orig.file)
+	if orig != nil {
+		switch {
+		case orig.file != nil:
+			if desc == nil || desc.file != orig.file {
+				f.drop(orig.file)
+			}
+		case orig.fileVFS2 != nil:
+			if desc == nil || desc.fileVFS2 != orig.fileVFS2 {
+				f.dropVFS2(orig.fileVFS2)
+			}
+		}
 	}
 
 	// Adjust used.
 	switch {
-	case orig == nil && file != nil:
+	case orig == nil && desc != nil:
 		atomic.AddInt32(&f.used, 1)
-	case orig != nil && file == nil:
+	case orig != nil && desc == nil:
 		atomic.AddInt32(&f.used, -1)
 	}
 }
diff --git a/pkg/sentry/kernel/futex/BUILD b/pkg/sentry/kernel/futex/BUILD
index 50db443ce..c5021f2db 100644
--- a/pkg/sentry/kernel/futex/BUILD
+++ b/pkg/sentry/kernel/futex/BUILD
@@ -1,6 +1,5 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -34,16 +33,15 @@ go_library(
         "futex.go",
         "waiter_list.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/futex",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/context",
         "//pkg/log",
-        "//pkg/sentry/context",
         "//pkg/sentry/memmap",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
     ],
 )
 
@@ -51,9 +49,9 @@ go_test(
     name = "futex_test",
     size = "small",
     srcs = ["futex_test.go"],
-    embed = [":futex"],
+    library = ":futex",
     deps = [
-        "//pkg/sentry/usermem",
         "//pkg/sync",
+        "//pkg/usermem",
     ],
 )
diff --git a/pkg/sentry/kernel/futex/futex.go b/pkg/sentry/kernel/futex/futex.go
index d1931c8f4..732e66da4 100644
--- a/pkg/sentry/kernel/futex/futex.go
+++ b/pkg/sentry/kernel/futex/futex.go
@@ -20,9 +20,9 @@ package futex
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // KeyKind indicates the type of a Key.
diff --git a/pkg/sentry/kernel/futex/futex_test.go b/pkg/sentry/kernel/futex/futex_test.go
index c23126ca5..7c5c7665b 100644
--- a/pkg/sentry/kernel/futex/futex_test.go
+++ b/pkg/sentry/kernel/futex/futex_test.go
@@ -22,8 +22,8 @@ import (
 	"testing"
 	"unsafe"
 
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // testData implements the Target interface, and allows us to
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index c85e97fef..dcd6e91c4 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -40,12 +40,12 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/eventchannel"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/timerfd"
 	"gvisor.dev/gvisor/pkg/sentry/hostcpu"
@@ -65,6 +65,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/unimpl"
 	uspb "gvisor.dev/gvisor/pkg/sentry/unimpl/unimplemented_syscall_go_proto"
 	"gvisor.dev/gvisor/pkg/sentry/uniqueid"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/state"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -435,17 +436,17 @@ func (k *Kernel) flushMountSourceRefs() error {
 
 	// There may be some open FDs whose filesystems have been unmounted. We
 	// must flush those as well.
-	return k.tasks.forEachFDPaused(func(file *fs.File) error {
+	return k.tasks.forEachFDPaused(func(file *fs.File, _ *vfs.FileDescription) error {
 		file.Dirent.Inode.MountSource.FlushDirentRefs()
 		return nil
 	})
 }
 
-// forEachFDPaused applies the given function to each open file descriptor in each
-// task.
+// forEachFDPaused applies the given function to each open file descriptor in
+// each task.
 //
 // Precondition: Must be called with the kernel paused.
-func (ts *TaskSet) forEachFDPaused(f func(*fs.File) error) (err error) {
+func (ts *TaskSet) forEachFDPaused(f func(*fs.File, *vfs.FileDescription) error) (err error) {
 	ts.mu.RLock()
 	defer ts.mu.RUnlock()
 	for t := range ts.Root.tids {
@@ -453,8 +454,8 @@ func (ts *TaskSet) forEachFDPaused(f func(*fs.File) error) (err error) {
 		if t.fdTable == nil {
 			continue
 		}
-		t.fdTable.forEach(func(_ int32, file *fs.File, _ FDFlags) {
-			if lastErr := f(file); lastErr != nil && err == nil {
+		t.fdTable.forEach(func(_ int32, file *fs.File, fileVFS2 *vfs.FileDescription, _ FDFlags) {
+			if lastErr := f(file, fileVFS2); lastErr != nil && err == nil {
 				err = lastErr
 			}
 		})
@@ -463,7 +464,8 @@ func (ts *TaskSet) forEachFDPaused(f func(*fs.File) error) (err error) {
 }
 
 func (ts *TaskSet) flushWritesToFiles(ctx context.Context) error {
-	return ts.forEachFDPaused(func(file *fs.File) error {
+	// TODO(gvisor.dev/issues/1663): Add save support for VFS2.
+	return ts.forEachFDPaused(func(file *fs.File, _ *vfs.FileDescription) error {
 		if flags := file.Flags(); !flags.Write {
 			return nil
 		}
@@ -474,12 +476,9 @@ func (ts *TaskSet) flushWritesToFiles(ctx context.Context) error {
 		syncErr := file.Fsync(ctx, 0, fs.FileMaxOffset, fs.SyncAll)
 		if err := fs.SaveFileFsyncError(syncErr); err != nil {
 			name, _ := file.Dirent.FullName(nil /* root */)
-			// Wrap this error in ErrSaveRejection
-			// so that it will trigger a save
-			// error, rather than a panic. This
-			// also allows us to distinguish Fsync
-			// errors from state file errors in
-			// state.Save.
+			// Wrap this error in ErrSaveRejection so that it will trigger a save
+			// error, rather than a panic. This also allows us to distinguish Fsync
+			// errors from state file errors in state.Save.
 			return fs.ErrSaveRejection{
 				Err: fmt.Errorf("%q was not sufficiently synced: %v", name, err),
 			}
@@ -519,7 +518,7 @@ func (ts *TaskSet) unregisterEpollWaiters() {
 	for t := range ts.Root.tids {
 		// We can skip locking Task.mu here since the kernel is paused.
 		if t.fdTable != nil {
-			t.fdTable.forEach(func(_ int32, file *fs.File, _ FDFlags) {
+			t.fdTable.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
 				if e, ok := file.FileOperations.(*epoll.EventPoll); ok {
 					e.UnregisterEpollWaiters()
 				}
@@ -921,7 +920,7 @@ func (k *Kernel) pauseTimeLocked() {
 		// This means we'll iterate FDTables shared by multiple tasks repeatedly,
 		// but ktime.Timer.Pause is idempotent so this is harmless.
 		if t.fdTable != nil {
-			t.fdTable.forEach(func(_ int32, file *fs.File, _ FDFlags) {
+			t.fdTable.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
 				if tfd, ok := file.FileOperations.(*timerfd.TimerOperations); ok {
 					tfd.PauseTimer()
 				}
@@ -951,7 +950,7 @@ func (k *Kernel) resumeTimeLocked() {
 			}
 		}
 		if t.fdTable != nil {
-			t.fdTable.forEach(func(_ int32, file *fs.File, _ FDFlags) {
+			t.fdTable.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
 				if tfd, ok := file.FileOperations.(*timerfd.TimerOperations); ok {
 					tfd.ResumeTimer()
 				}
diff --git a/pkg/sentry/kernel/memevent/BUILD b/pkg/sentry/kernel/memevent/BUILD
index 7f36252a9..4486848d2 100644
--- a/pkg/sentry/kernel/memevent/BUILD
+++ b/pkg/sentry/kernel/memevent/BUILD
@@ -1,13 +1,10 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
-load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
-load("@rules_cc//cc:defs.bzl", "cc_proto_library")
+load("//tools:defs.bzl", "go_library", "proto_library")
 
 package(licenses = ["notice"])
 
 go_library(
     name = "memevent",
     srcs = ["memory_events.go"],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/memevent",
     visibility = ["//:sandbox"],
     deps = [
         ":memory_events_go_proto",
@@ -21,20 +18,7 @@ go_library(
 )
 
 proto_library(
-    name = "memory_events_proto",
+    name = "memory_events",
     srcs = ["memory_events.proto"],
     visibility = ["//visibility:public"],
 )
-
-cc_proto_library(
-    name = "memory_events_cc_proto",
-    visibility = ["//visibility:public"],
-    deps = [":memory_events_proto"],
-)
-
-go_proto_library(
-    name = "memory_events_go_proto",
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/memevent/memory_events_go_proto",
-    proto = ":memory_events_proto",
-    visibility = ["//visibility:public"],
-)
diff --git a/pkg/sentry/kernel/pipe/BUILD b/pkg/sentry/kernel/pipe/BUILD
index 5eeaeff66..4c049d5b4 100644
--- a/pkg/sentry/kernel/pipe/BUILD
+++ b/pkg/sentry/kernel/pipe/BUILD
@@ -1,6 +1,5 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -30,21 +29,20 @@ go_library(
         "vfs.go",
         "writer.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/pipe",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
         "//pkg/amutex",
+        "//pkg/context",
+        "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/context",
         "//pkg/sentry/device",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/fsutil",
-        "//pkg/sentry/safemem",
-        "//pkg/sentry/usermem",
         "//pkg/sentry/vfs",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
@@ -57,13 +55,13 @@ go_test(
         "node_test.go",
         "pipe_test.go",
     ],
-    embed = [":pipe"],
+    library = ":pipe",
     deps = [
-        "//pkg/sentry/context",
-        "//pkg/sentry/context/contexttest",
+        "//pkg/context",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/fs",
-        "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
diff --git a/pkg/sentry/kernel/pipe/buffer.go b/pkg/sentry/kernel/pipe/buffer.go
index 1c0f34269..fe3be5dbd 100644
--- a/pkg/sentry/kernel/pipe/buffer.go
+++ b/pkg/sentry/kernel/pipe/buffer.go
@@ -17,7 +17,7 @@ package pipe
 import (
 	"io"
 
-	"gvisor.dev/gvisor/pkg/sentry/safemem"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sync"
 )
 
diff --git a/pkg/sentry/kernel/pipe/buffer_test.go b/pkg/sentry/kernel/pipe/buffer_test.go
index ee1b90115..4d54b8b8f 100644
--- a/pkg/sentry/kernel/pipe/buffer_test.go
+++ b/pkg/sentry/kernel/pipe/buffer_test.go
@@ -18,7 +18,7 @@ import (
 	"testing"
 	"unsafe"
 
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 func TestBufferSize(t *testing.T) {
diff --git a/pkg/sentry/kernel/pipe/node.go b/pkg/sentry/kernel/pipe/node.go
index 716f589af..4b688c627 100644
--- a/pkg/sentry/kernel/pipe/node.go
+++ b/pkg/sentry/kernel/pipe/node.go
@@ -16,7 +16,7 @@ package pipe
 
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.dev/gvisor/pkg/sync"
diff --git a/pkg/sentry/kernel/pipe/node_test.go b/pkg/sentry/kernel/pipe/node_test.go
index 16fa80abe..ab75a87ff 100644
--- a/pkg/sentry/kernel/pipe/node_test.go
+++ b/pkg/sentry/kernel/pipe/node_test.go
@@ -18,11 +18,11 @@ import (
 	"testing"
 	"time"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 type sleeper struct {
diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go
index e4fd7d420..08410283f 100644
--- a/pkg/sentry/kernel/pipe/pipe.go
+++ b/pkg/sentry/kernel/pipe/pipe.go
@@ -20,7 +20,7 @@ import (
 	"sync/atomic"
 	"syscall"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
diff --git a/pkg/sentry/kernel/pipe/pipe_test.go b/pkg/sentry/kernel/pipe/pipe_test.go
index e3a14b665..bda739dbe 100644
--- a/pkg/sentry/kernel/pipe/pipe_test.go
+++ b/pkg/sentry/kernel/pipe/pipe_test.go
@@ -18,9 +18,9 @@ import (
 	"bytes"
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/pipe/pipe_util.go b/pkg/sentry/kernel/pipe/pipe_util.go
index 8394eb78b..80158239e 100644
--- a/pkg/sentry/kernel/pipe/pipe_util.go
+++ b/pkg/sentry/kernel/pipe/pipe_util.go
@@ -21,10 +21,10 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/amutex"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/pipe/reader_writer.go b/pkg/sentry/kernel/pipe/reader_writer.go
index b4d29fc77..b2b5691ee 100644
--- a/pkg/sentry/kernel/pipe/reader_writer.go
+++ b/pkg/sentry/kernel/pipe/reader_writer.go
@@ -17,11 +17,11 @@ package pipe
 import (
 	"io"
 
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // ReaderWriter satisfies the FileOperations interface and services both
diff --git a/pkg/sentry/kernel/pipe/vfs.go b/pkg/sentry/kernel/pipe/vfs.go
index 6f83e3cee..a5675bd70 100644
--- a/pkg/sentry/kernel/pipe/vfs.go
+++ b/pkg/sentry/kernel/pipe/vfs.go
@@ -16,12 +16,12 @@ package pipe
 
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/ptrace.go b/pkg/sentry/kernel/ptrace.go
index 3be171cdc..35ad97d5d 100644
--- a/pkg/sentry/kernel/ptrace.go
+++ b/pkg/sentry/kernel/ptrace.go
@@ -20,8 +20,8 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // ptraceOptions are the subset of options controlling a task's ptrace behavior
diff --git a/pkg/sentry/kernel/ptrace_amd64.go b/pkg/sentry/kernel/ptrace_amd64.go
index 5514cf432..cef1276ec 100644
--- a/pkg/sentry/kernel/ptrace_amd64.go
+++ b/pkg/sentry/kernel/ptrace_amd64.go
@@ -18,8 +18,8 @@ package kernel
 
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // ptraceArch implements arch-specific ptrace commands.
diff --git a/pkg/sentry/kernel/ptrace_arm64.go b/pkg/sentry/kernel/ptrace_arm64.go
index 61e412911..d971b96b3 100644
--- a/pkg/sentry/kernel/ptrace_arm64.go
+++ b/pkg/sentry/kernel/ptrace_arm64.go
@@ -17,8 +17,8 @@
 package kernel
 
 import (
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // ptraceArch implements arch-specific ptrace commands.
diff --git a/pkg/sentry/kernel/rseq.go b/pkg/sentry/kernel/rseq.go
index b14429854..efebfd872 100644
--- a/pkg/sentry/kernel/rseq.go
+++ b/pkg/sentry/kernel/rseq.go
@@ -19,8 +19,8 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/sentry/hostcpu"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Restartable sequences.
diff --git a/pkg/sentry/kernel/sched/BUILD b/pkg/sentry/kernel/sched/BUILD
index 98ea7a0d8..1b82e087b 100644
--- a/pkg/sentry/kernel/sched/BUILD
+++ b/pkg/sentry/kernel/sched/BUILD
@@ -1,5 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 
 package(licenses = ["notice"])
 
@@ -9,7 +8,6 @@ go_library(
         "cpuset.go",
         "sched.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/sched",
     visibility = ["//pkg/sentry:internal"],
 )
 
@@ -17,5 +15,5 @@ go_test(
     name = "sched_test",
     size = "small",
     srcs = ["cpuset_test.go"],
-    embed = [":sched"],
+    library = ":sched",
 )
diff --git a/pkg/sentry/kernel/seccomp.go b/pkg/sentry/kernel/seccomp.go
index 2347dcf36..c38c5a40c 100644
--- a/pkg/sentry/kernel/seccomp.go
+++ b/pkg/sentry/kernel/seccomp.go
@@ -21,8 +21,8 @@ import (
 	"gvisor.dev/gvisor/pkg/binary"
 	"gvisor.dev/gvisor/pkg/bpf"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 const maxSyscallFilterInstructions = 1 << 15
diff --git a/pkg/sentry/kernel/semaphore/BUILD b/pkg/sentry/kernel/semaphore/BUILD
index 13a961594..65e5427c1 100644
--- a/pkg/sentry/kernel/semaphore/BUILD
+++ b/pkg/sentry/kernel/semaphore/BUILD
@@ -1,6 +1,5 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -22,12 +21,11 @@ go_library(
         "semaphore.go",
         "waiter_list.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/semaphore",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/context",
         "//pkg/log",
-        "//pkg/sentry/context",
         "//pkg/sentry/fs",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/kernel/time",
@@ -40,11 +38,11 @@ go_test(
     name = "semaphore_test",
     size = "small",
     srcs = ["semaphore_test.go"],
-    embed = [":semaphore"],
+    library = ":semaphore",
     deps = [
         "//pkg/abi/linux",
-        "//pkg/sentry/context",
-        "//pkg/sentry/context/contexttest",
+        "//pkg/context",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/kernel/auth",
         "//pkg/syserror",
     ],
diff --git a/pkg/sentry/kernel/semaphore/semaphore.go b/pkg/sentry/kernel/semaphore/semaphore.go
index 18299814e..1000f3287 100644
--- a/pkg/sentry/kernel/semaphore/semaphore.go
+++ b/pkg/sentry/kernel/semaphore/semaphore.go
@@ -19,8 +19,8 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
diff --git a/pkg/sentry/kernel/semaphore/semaphore_test.go b/pkg/sentry/kernel/semaphore/semaphore_test.go
index c235f6ca4..e47acefdf 100644
--- a/pkg/sentry/kernel/semaphore/semaphore_test.go
+++ b/pkg/sentry/kernel/semaphore/semaphore_test.go
@@ -18,8 +18,8 @@ import (
 	"testing"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
diff --git a/pkg/sentry/kernel/shm/BUILD b/pkg/sentry/kernel/shm/BUILD
index 7321b22ed..bfd779837 100644
--- a/pkg/sentry/kernel/shm/BUILD
+++ b/pkg/sentry/kernel/shm/BUILD
@@ -1,4 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -8,13 +8,12 @@ go_library(
         "device.go",
         "shm.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/shm",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/context",
         "//pkg/log",
         "//pkg/refs",
-        "//pkg/sentry/context",
         "//pkg/sentry/device",
         "//pkg/sentry/fs",
         "//pkg/sentry/kernel/auth",
@@ -23,8 +22,8 @@ go_library(
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
         "//pkg/sentry/usage",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
     ],
 )
diff --git a/pkg/sentry/kernel/shm/shm.go b/pkg/sentry/kernel/shm/shm.go
index 8ddef7eb8..208569057 100644
--- a/pkg/sentry/kernel/shm/shm.go
+++ b/pkg/sentry/kernel/shm/shm.go
@@ -37,9 +37,9 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/refs"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
@@ -47,9 +47,9 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Key represents a shm segment key. Analogous to a file name.
diff --git a/pkg/sentry/kernel/signalfd/BUILD b/pkg/sentry/kernel/signalfd/BUILD
index 89e4d84b1..3eb78e91b 100644
--- a/pkg/sentry/kernel/signalfd/BUILD
+++ b/pkg/sentry/kernel/signalfd/BUILD
@@ -1,23 +1,22 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
 
-package(licenses = ["notice"])
+licenses(["notice"])
 
 go_library(
     name = "signalfd",
     srcs = ["signalfd.go"],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/signalfd",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
         "//pkg/binary",
-        "//pkg/sentry/context",
+        "//pkg/context",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/anon",
         "//pkg/sentry/fs/fsutil",
         "//pkg/sentry/kernel",
-        "//pkg/sentry/usermem",
         "//pkg/sync",
         "//pkg/syserror",
+        "//pkg/usermem",
         "//pkg/waiter",
     ],
 )
diff --git a/pkg/sentry/kernel/signalfd/signalfd.go b/pkg/sentry/kernel/signalfd/signalfd.go
index 28be4a939..8243bb93e 100644
--- a/pkg/sentry/kernel/signalfd/signalfd.go
+++ b/pkg/sentry/kernel/signalfd/signalfd.go
@@ -18,14 +18,14 @@ package signalfd
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/binary"
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/anon"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/syscalls.go b/pkg/sentry/kernel/syscalls.go
index d2d01add4..93c4fe969 100644
--- a/pkg/sentry/kernel/syscalls.go
+++ b/pkg/sentry/kernel/syscalls.go
@@ -21,8 +21,8 @@ import (
 	"gvisor.dev/gvisor/pkg/abi"
 	"gvisor.dev/gvisor/pkg/bits"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // maxSyscallNum is the highest supported syscall number.
diff --git a/pkg/sentry/kernel/task.go b/pkg/sentry/kernel/task.go
index 978d66da8..981e8c7fe 100644
--- a/pkg/sentry/kernel/task.go
+++ b/pkg/sentry/kernel/task.go
@@ -21,8 +21,8 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/bpf"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/inet"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
@@ -35,8 +35,9 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/unimpl"
 	"gvisor.dev/gvisor/pkg/sentry/uniqueid"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
@@ -743,6 +744,14 @@ func (t *Task) GetFile(fd int32) *fs.File {
 	return f
 }
 
+// GetFileVFS2 is a convenience wrapper for t.FDTable().GetVFS2.
+//
+// Precondition: same as FDTable.Get.
+func (t *Task) GetFileVFS2(fd int32) *vfs.FileDescription {
+	f, _ := t.fdTable.GetVFS2(fd)
+	return f
+}
+
 // NewFDs is a convenience wrapper for t.FDTable().NewFDs.
 //
 // This automatically passes the task as the context.
diff --git a/pkg/sentry/kernel/task_clone.go b/pkg/sentry/kernel/task_clone.go
index 247bd4aba..53d4d211b 100644
--- a/pkg/sentry/kernel/task_clone.go
+++ b/pkg/sentry/kernel/task_clone.go
@@ -17,8 +17,8 @@ package kernel
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/bpf"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // SharingOptions controls what resources are shared by a new task created by
diff --git a/pkg/sentry/kernel/task_context.go b/pkg/sentry/kernel/task_context.go
index bb5560acf..2d6e7733c 100644
--- a/pkg/sentry/kernel/task_context.go
+++ b/pkg/sentry/kernel/task_context.go
@@ -18,13 +18,13 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/futex"
 	"gvisor.dev/gvisor/pkg/sentry/loader"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserr"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 var errNoSyscalls = syserr.New("no syscall table found", linux.ENOEXEC)
diff --git a/pkg/sentry/kernel/task_exec.go b/pkg/sentry/kernel/task_exec.go
index fa6528386..8f57a34a6 100644
--- a/pkg/sentry/kernel/task_exec.go
+++ b/pkg/sentry/kernel/task_exec.go
@@ -69,6 +69,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
@@ -198,7 +199,7 @@ func (r *runSyscallAfterExecStop) execute(t *Task) taskRunState {
 	t.tg.pidns.owner.mu.Unlock()
 
 	// Remove FDs with the CloseOnExec flag set.
-	t.fdTable.RemoveIf(func(file *fs.File, flags FDFlags) bool {
+	t.fdTable.RemoveIf(func(_ *fs.File, _ *vfs.FileDescription, flags FDFlags) bool {
 		return flags.CloseOnExec
 	})
 
diff --git a/pkg/sentry/kernel/task_futex.go b/pkg/sentry/kernel/task_futex.go
index c211b5b74..a53e77c9f 100644
--- a/pkg/sentry/kernel/task_futex.go
+++ b/pkg/sentry/kernel/task_futex.go
@@ -16,7 +16,7 @@ package kernel
 
 import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel/futex"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Futex returns t's futex manager.
diff --git a/pkg/sentry/kernel/task_log.go b/pkg/sentry/kernel/task_log.go
index 0fb3661de..41259210c 100644
--- a/pkg/sentry/kernel/task_log.go
+++ b/pkg/sentry/kernel/task_log.go
@@ -20,7 +20,7 @@ import (
 	"sort"
 
 	"gvisor.dev/gvisor/pkg/log"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 const (
diff --git a/pkg/sentry/kernel/task_run.go b/pkg/sentry/kernel/task_run.go
index 6357273d3..5568c91bc 100644
--- a/pkg/sentry/kernel/task_run.go
+++ b/pkg/sentry/kernel/task_run.go
@@ -26,7 +26,7 @@ import (
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // A taskRunState is a reified state in the task state machine. See README.md
diff --git a/pkg/sentry/kernel/task_signals.go b/pkg/sentry/kernel/task_signals.go
index 39cd1340d..8802db142 100644
--- a/pkg/sentry/kernel/task_signals.go
+++ b/pkg/sentry/kernel/task_signals.go
@@ -26,8 +26,8 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	ucspb "gvisor.dev/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
diff --git a/pkg/sentry/kernel/task_start.go b/pkg/sentry/kernel/task_start.go
index 58af16ee2..de838beef 100644
--- a/pkg/sentry/kernel/task_start.go
+++ b/pkg/sentry/kernel/task_start.go
@@ -21,8 +21,8 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel/futex"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/sched"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // TaskConfig defines the configuration of a new Task (see below).
diff --git a/pkg/sentry/kernel/task_syscall.go b/pkg/sentry/kernel/task_syscall.go
index 3180f5560..d555d69a8 100644
--- a/pkg/sentry/kernel/task_syscall.go
+++ b/pkg/sentry/kernel/task_syscall.go
@@ -25,8 +25,8 @@ import (
 	"gvisor.dev/gvisor/pkg/metric"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // SyscallRestartErrno represents a ERESTART* errno defined in the Linux's kernel
diff --git a/pkg/sentry/kernel/task_usermem.go b/pkg/sentry/kernel/task_usermem.go
index 518bfe1bd..2bf3ce8a8 100644
--- a/pkg/sentry/kernel/task_usermem.go
+++ b/pkg/sentry/kernel/task_usermem.go
@@ -18,8 +18,8 @@ import (
 	"math"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // MAX_RW_COUNT is the maximum size in bytes of a single read or write.
diff --git a/pkg/sentry/kernel/time/BUILD b/pkg/sentry/kernel/time/BUILD
index 4e4de0512..7ba7dc50c 100644
--- a/pkg/sentry/kernel/time/BUILD
+++ b/pkg/sentry/kernel/time/BUILD
@@ -1,4 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -8,11 +8,10 @@ go_library(
         "context.go",
         "time.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/kernel/time",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
-        "//pkg/sentry/context",
+        "//pkg/context",
         "//pkg/sync",
         "//pkg/syserror",
         "//pkg/waiter",
diff --git a/pkg/sentry/kernel/time/context.go b/pkg/sentry/kernel/time/context.go
index 8ef483dd3..00b729d88 100644
--- a/pkg/sentry/kernel/time/context.go
+++ b/pkg/sentry/kernel/time/context.go
@@ -15,7 +15,7 @@
 package time
 
 import (
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 )
 
 // contextID is the time package's type for context.Context.Value keys.
diff --git a/pkg/sentry/kernel/timekeeper_test.go b/pkg/sentry/kernel/timekeeper_test.go
index 849c5b646..cf2f7ca72 100644
--- a/pkg/sentry/kernel/timekeeper_test.go
+++ b/pkg/sentry/kernel/timekeeper_test.go
@@ -17,12 +17,12 @@ package kernel
 import (
 	"testing"
 
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	sentrytime "gvisor.dev/gvisor/pkg/sentry/time"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // mockClocks is a sentrytime.Clocks that simply returns the times in the
diff --git a/pkg/sentry/kernel/tty.go b/pkg/sentry/kernel/tty.go
index 464d2306a..d0e0810e8 100644
--- a/pkg/sentry/kernel/tty.go
+++ b/pkg/sentry/kernel/tty.go
@@ -33,6 +33,8 @@ type TTY struct {
 // TTY returns the thread group's controlling terminal. If nil, there is no
 // controlling terminal.
 func (tg *ThreadGroup) TTY() *TTY {
+	tg.pidns.owner.mu.RLock()
+	defer tg.pidns.owner.mu.RUnlock()
 	tg.signalHandlers.mu.Lock()
 	defer tg.signalHandlers.mu.Unlock()
 	return tg.tty
diff --git a/pkg/sentry/kernel/vdso.go b/pkg/sentry/kernel/vdso.go
index fdd10c56c..f1b3c212c 100644
--- a/pkg/sentry/kernel/vdso.go
+++ b/pkg/sentry/kernel/vdso.go
@@ -18,10 +18,10 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/binary"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/safemem"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // vdsoParams are the parameters exposed to the VDSO.