3 files changed, 635 insertions, 0 deletions
diff --git a/pkg/sentry/kernel/msgqueue/message_list.go b/pkg/sentry/kernel/msgqueue/message_list.go
new file mode 100644
index 000000000..f2f2292e7
--- /dev/null
+++ b/pkg/sentry/kernel/msgqueue/message_list.go
@@ -0,0 +1,221 @@
+package msgqueue
+
+// ElementMapper provides an identity mapping by default.
+//
+// This can be replaced to provide a struct that maps elements to linker
+// objects, if they are not the same. An ElementMapper is not typically
+// required if: Linker is left as is, Element is left as is, or Linker and
+// Element are the same type.
+type msgElementMapper struct{}
+
+// linkerFor maps an Element to a Linker.
+//
+// This default implementation should be inlined.
+//
+//go:nosplit
+func (msgElementMapper) linkerFor(elem *Message) *Message { return elem }
+
+// List is an intrusive list. Entries can be added to or removed from the list
+// in O(1) time and with no additional memory allocations.
+//
+// The zero value for List is an empty list ready to use.
+//
+// To iterate over a list (where l is a List):
+//      for e := l.Front(); e != nil; e = e.Next() {
+// 		// do something with e.
+//      }
+//
+// +stateify savable
+type msgList struct {
+	head *Message
+	tail *Message
+}
+
+// Reset resets list l to the empty state.
+func (l *msgList) Reset() {
+	l.head = nil
+	l.tail = nil
+}
+
+// Empty returns true iff the list is empty.
+//
+//go:nosplit
+func (l *msgList) Empty() bool {
+	return l.head == nil
+}
+
+// Front returns the first element of list l or nil.
+//
+//go:nosplit
+func (l *msgList) Front() *Message {
+	return l.head
+}
+
+// Back returns the last element of list l or nil.
+//
+//go:nosplit
+func (l *msgList) Back() *Message {
+	return l.tail
+}
+
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+//
+//go:nosplit
+func (l *msgList) Len() (count int) {
+	for e := l.Front(); e != nil; e = (msgElementMapper{}.linkerFor(e)).Next() {
+		count++
+	}
+	return count
+}
+
+// PushFront inserts the element e at the front of list l.
+//
+//go:nosplit
+func (l *msgList) PushFront(e *Message) {
+	linker := msgElementMapper{}.linkerFor(e)
+	linker.SetNext(l.head)
+	linker.SetPrev(nil)
+	if l.head != nil {
+		msgElementMapper{}.linkerFor(l.head).SetPrev(e)
+	} else {
+		l.tail = e
+	}
+
+	l.head = e
+}
+
+// PushBack inserts the element e at the back of list l.
+//
+//go:nosplit
+func (l *msgList) PushBack(e *Message) {
+	linker := msgElementMapper{}.linkerFor(e)
+	linker.SetNext(nil)
+	linker.SetPrev(l.tail)
+	if l.tail != nil {
+		msgElementMapper{}.linkerFor(l.tail).SetNext(e)
+	} else {
+		l.head = e
+	}
+
+	l.tail = e
+}
+
+// PushBackList inserts list m at the end of list l, emptying m.
+//
+//go:nosplit
+func (l *msgList) PushBackList(m *msgList) {
+	if l.head == nil {
+		l.head = m.head
+		l.tail = m.tail
+	} else if m.head != nil {
+		msgElementMapper{}.linkerFor(l.tail).SetNext(m.head)
+		msgElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
+
+		l.tail = m.tail
+	}
+	m.head = nil
+	m.tail = nil
+}
+
+// InsertAfter inserts e after b.
+//
+//go:nosplit
+func (l *msgList) InsertAfter(b, e *Message) {
+	bLinker := msgElementMapper{}.linkerFor(b)
+	eLinker := msgElementMapper{}.linkerFor(e)
+
+	a := bLinker.Next()
+
+	eLinker.SetNext(a)
+	eLinker.SetPrev(b)
+	bLinker.SetNext(e)
+
+	if a != nil {
+		msgElementMapper{}.linkerFor(a).SetPrev(e)
+	} else {
+		l.tail = e
+	}
+}
+
+// InsertBefore inserts e before a.
+//
+//go:nosplit
+func (l *msgList) InsertBefore(a, e *Message) {
+	aLinker := msgElementMapper{}.linkerFor(a)
+	eLinker := msgElementMapper{}.linkerFor(e)
+
+	b := aLinker.Prev()
+	eLinker.SetNext(a)
+	eLinker.SetPrev(b)
+	aLinker.SetPrev(e)
+
+	if b != nil {
+		msgElementMapper{}.linkerFor(b).SetNext(e)
+	} else {
+		l.head = e
+	}
+}
+
+// Remove removes e from l.
+//
+//go:nosplit
+func (l *msgList) Remove(e *Message) {
+	linker := msgElementMapper{}.linkerFor(e)
+	prev := linker.Prev()
+	next := linker.Next()
+
+	if prev != nil {
+		msgElementMapper{}.linkerFor(prev).SetNext(next)
+	} else if l.head == e {
+		l.head = next
+	}
+
+	if next != nil {
+		msgElementMapper{}.linkerFor(next).SetPrev(prev)
+	} else if l.tail == e {
+		l.tail = prev
+	}
+
+	linker.SetNext(nil)
+	linker.SetPrev(nil)
+}
+
+// Entry is a default implementation of Linker. Users can add anonymous fields
+// of this type to their structs to make them automatically implement the
+// methods needed by List.
+//
+// +stateify savable
+type msgEntry struct {
+	next *Message
+	prev *Message
+}
+
+// Next returns the entry that follows e in the list.
+//
+//go:nosplit
+func (e *msgEntry) Next() *Message {
+	return e.next
+}
+
+// Prev returns the entry that precedes e in the list.
+//
+//go:nosplit
+func (e *msgEntry) Prev() *Message {
+	return e.prev
+}
+
+// SetNext assigns 'entry' as the entry that follows e in the list.
+//
+//go:nosplit
+func (e *msgEntry) SetNext(elem *Message) {
+	e.next = elem
+}
+
+// SetPrev assigns 'entry' as the entry that precedes e in the list.
+//
+//go:nosplit
+func (e *msgEntry) SetPrev(elem *Message) {
+	e.prev = elem
+}
diff --git a/pkg/sentry/kernel/msgqueue/msgqueue.go b/pkg/sentry/kernel/msgqueue/msgqueue.go
new file mode 100644
index 000000000..3ce926950
--- /dev/null
+++ b/pkg/sentry/kernel/msgqueue/msgqueue.go
@@ -0,0 +1,220 @@
+// Copyright 2021 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 msgqueue implements System V message queues.
+package msgqueue
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
+	"gvisor.dev/gvisor/pkg/sentry/fs"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/ipc"
+	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
+	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+	// System-wide limit for maximum number of queues.
+	maxQueues = linux.MSGMNI
+
+	// Maximum size of a queue in bytes.
+	maxQueueBytes = linux.MSGMNB
+
+	// Maximum size of a message in bytes.
+	maxMessageBytes = linux.MSGMAX
+)
+
+// Registry contains a set of message queues that can be referenced using keys
+// or IDs.
+//
+// +stateify savable
+type Registry struct {
+	// mu protects all the fields below.
+	mu sync.Mutex `state:"nosave"`
+
+	// reg defines basic fields and operations needed for all SysV registries.
+	reg *ipc.Registry
+}
+
+// NewRegistry returns a new Registry ready to be used.
+func NewRegistry(userNS *auth.UserNamespace) *Registry {
+	return &Registry{
+		reg: ipc.NewRegistry(userNS),
+	}
+}
+
+// Queue represents a SysV message queue, described by sysvipc(7).
+//
+// +stateify savable
+type Queue struct {
+	// registry is the registry owning this queue. Immutable.
+	registry *Registry
+
+	// mu protects all the fields below.
+	mu sync.Mutex `state:"nosave"`
+
+	// dead is set to true when a queue is removed from the registry and should
+	// not be used. Operations on the queue should check dead, and return
+	// EIDRM if set to true.
+	dead bool
+
+	// obj defines basic fields that should be included in all SysV IPC objects.
+	obj *ipc.Object
+
+	// senders holds a queue of blocked message senders. Senders are notified
+	// when enough space is available in the queue to insert their message.
+	senders waiter.Queue
+
+	// receivers holds a queue of blocked receivers. Receivers are notified
+	// when a new message is inserted into the queue and can be received.
+	receivers waiter.Queue
+
+	// messages is a list of sent messages.
+	messages msgList
+
+	// sendTime is the last time a msgsnd was perfomed.
+	sendTime ktime.Time
+
+	// receiveTime is the last time a msgrcv was performed.
+	receiveTime ktime.Time
+
+	// changeTime is the last time the queue was modified using msgctl.
+	changeTime ktime.Time
+
+	// byteCount is the current number of message bytes in the queue.
+	byteCount uint64
+
+	// messageCount is the current number of messages in the queue.
+	messageCount uint64
+
+	// maxBytes is the maximum allowed number of bytes in the queue, and is also
+	// used as a limit for the number of total possible messages.
+	maxBytes uint64
+
+	// sendPID is the PID of the process that performed the last msgsnd.
+	sendPID int32
+
+	// receivePID is the PID of the process that performed the last msgrcv.
+	receivePID int32
+}
+
+// Message represents a message exchanged through a Queue via msgsnd(2) and
+// msgrcv(2).
+//
+// +stateify savable
+type Message struct {
+	msgEntry
+
+	// mType is an integer representing the type of the sent message.
+	mType int64
+
+	// mText is an untyped block of memory.
+	mText []byte
+
+	// mSize is the size of mText.
+	mSize uint64
+}
+
+// FindOrCreate creates a new message queue or returns an existing one. See
+// msgget(2).
+func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, mode linux.FileMode, private, create, exclusive bool) (*Queue, error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if !private {
+		queue, err := r.reg.Find(ctx, key, mode, create, exclusive)
+		if err != nil {
+			return nil, err
+		}
+
+		if queue != nil {
+			return queue.(*Queue), nil
+		}
+	}
+
+	// Check system-wide limits.
+	if r.reg.ObjectCount() >= maxQueues {
+		return nil, linuxerr.ENOSPC
+	}
+
+	return r.newQueueLocked(ctx, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode))
+}
+
+// newQueueLocked creates a new queue using the given fields. An error is
+// returned if there're no more available identifiers.
+//
+// Precondition: r.mu must be held.
+func (r *Registry) newQueueLocked(ctx context.Context, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions) (*Queue, error) {
+	q := &Queue{
+		registry:    r,
+		obj:         ipc.NewObject(r.reg.UserNS, key, creator, creator, perms),
+		sendTime:    ktime.ZeroTime,
+		receiveTime: ktime.ZeroTime,
+		changeTime:  ktime.NowFromContext(ctx),
+		maxBytes:    maxQueueBytes,
+	}
+
+	err := r.reg.Register(q)
+	if err != nil {
+		return nil, err
+	}
+	return q, nil
+}
+
+// Remove removes the queue with specified ID. All waiters (readers and
+// writers) and writers will be awakened and fail. Remove will return an error
+// if the ID is invalid, or the the user doesn't have privileges.
+func (r *Registry) Remove(id ipc.ID, creds *auth.Credentials) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.reg.Remove(id, creds)
+	return nil
+}
+
+// Lock implements ipc.Mechanism.Lock.
+func (q *Queue) Lock() {
+	q.mu.Lock()
+}
+
+// Unlock implements ipc.mechanism.Unlock.
+//
+// +checklocksignore
+func (q *Queue) Unlock() {
+	q.mu.Unlock()
+}
+
+// Object implements ipc.Mechanism.Object.
+func (q *Queue) Object() *ipc.Object {
+	return q.obj
+}
+
+// Destroy implements ipc.Mechanism.Destroy.
+func (q *Queue) Destroy() {
+	q.dead = true
+
+	// Notify waiters. Senders and receivers will try to run, and return an
+	// error (EIDRM). Waiters should remove themselves from the queue after
+	// waking up.
+	q.senders.Notify(waiter.EventOut)
+	q.receivers.Notify(waiter.EventIn)
+}
+
+// ID returns queue's ID.
+func (q *Queue) ID() ipc.ID {
+	return q.obj.ID
+}
diff --git a/pkg/sentry/kernel/msgqueue/msgqueue_state_autogen.go b/pkg/sentry/kernel/msgqueue/msgqueue_state_autogen.go
new file mode 100644
index 000000000..3dfcd09cb
--- /dev/null
+++ b/pkg/sentry/kernel/msgqueue/msgqueue_state_autogen.go
@@ -0,0 +1,194 @@
+// automatically generated by stateify.
+
+package msgqueue
+
+import (
+	"gvisor.dev/gvisor/pkg/state"
+)
+
+func (l *msgList) StateTypeName() string {
+	return "pkg/sentry/kernel/msgqueue.msgList"
+}
+
+func (l *msgList) StateFields() []string {
+	return []string{
+		"head",
+		"tail",
+	}
+}
+
+func (l *msgList) beforeSave() {}
+
+// +checklocksignore
+func (l *msgList) StateSave(stateSinkObject state.Sink) {
+	l.beforeSave()
+	stateSinkObject.Save(0, &l.head)
+	stateSinkObject.Save(1, &l.tail)
+}
+
+func (l *msgList) afterLoad() {}
+
+// +checklocksignore
+func (l *msgList) StateLoad(stateSourceObject state.Source) {
+	stateSourceObject.Load(0, &l.head)
+	stateSourceObject.Load(1, &l.tail)
+}
+
+func (e *msgEntry) StateTypeName() string {
+	return "pkg/sentry/kernel/msgqueue.msgEntry"
+}
+
+func (e *msgEntry) StateFields() []string {
+	return []string{
+		"next",
+		"prev",
+	}
+}
+
+func (e *msgEntry) beforeSave() {}
+
+// +checklocksignore
+func (e *msgEntry) StateSave(stateSinkObject state.Sink) {
+	e.beforeSave()
+	stateSinkObject.Save(0, &e.next)
+	stateSinkObject.Save(1, &e.prev)
+}
+
+func (e *msgEntry) afterLoad() {}
+
+// +checklocksignore
+func (e *msgEntry) StateLoad(stateSourceObject state.Source) {
+	stateSourceObject.Load(0, &e.next)
+	stateSourceObject.Load(1, &e.prev)
+}
+
+func (r *Registry) StateTypeName() string {
+	return "pkg/sentry/kernel/msgqueue.Registry"
+}
+
+func (r *Registry) StateFields() []string {
+	return []string{
+		"reg",
+	}
+}
+
+func (r *Registry) beforeSave() {}
+
+// +checklocksignore
+func (r *Registry) StateSave(stateSinkObject state.Sink) {
+	r.beforeSave()
+	stateSinkObject.Save(0, &r.reg)
+}
+
+func (r *Registry) afterLoad() {}
+
+// +checklocksignore
+func (r *Registry) StateLoad(stateSourceObject state.Source) {
+	stateSourceObject.Load(0, &r.reg)
+}
+
+func (q *Queue) StateTypeName() string {
+	return "pkg/sentry/kernel/msgqueue.Queue"
+}
+
+func (q *Queue) StateFields() []string {
+	return []string{
+		"registry",
+		"dead",
+		"obj",
+		"senders",
+		"receivers",
+		"messages",
+		"sendTime",
+		"receiveTime",
+		"changeTime",
+		"byteCount",
+		"messageCount",
+		"maxBytes",
+		"sendPID",
+		"receivePID",
+	}
+}
+
+func (q *Queue) beforeSave() {}
+
+// +checklocksignore
+func (q *Queue) StateSave(stateSinkObject state.Sink) {
+	q.beforeSave()
+	stateSinkObject.Save(0, &q.registry)
+	stateSinkObject.Save(1, &q.dead)
+	stateSinkObject.Save(2, &q.obj)
+	stateSinkObject.Save(3, &q.senders)
+	stateSinkObject.Save(4, &q.receivers)
+	stateSinkObject.Save(5, &q.messages)
+	stateSinkObject.Save(6, &q.sendTime)
+	stateSinkObject.Save(7, &q.receiveTime)
+	stateSinkObject.Save(8, &q.changeTime)
+	stateSinkObject.Save(9, &q.byteCount)
+	stateSinkObject.Save(10, &q.messageCount)
+	stateSinkObject.Save(11, &q.maxBytes)
+	stateSinkObject.Save(12, &q.sendPID)
+	stateSinkObject.Save(13, &q.receivePID)
+}
+
+func (q *Queue) afterLoad() {}
+
+// +checklocksignore
+func (q *Queue) StateLoad(stateSourceObject state.Source) {
+	stateSourceObject.Load(0, &q.registry)
+	stateSourceObject.Load(1, &q.dead)
+	stateSourceObject.Load(2, &q.obj)
+	stateSourceObject.Load(3, &q.senders)
+	stateSourceObject.Load(4, &q.receivers)
+	stateSourceObject.Load(5, &q.messages)
+	stateSourceObject.Load(6, &q.sendTime)
+	stateSourceObject.Load(7, &q.receiveTime)
+	stateSourceObject.Load(8, &q.changeTime)
+	stateSourceObject.Load(9, &q.byteCount)
+	stateSourceObject.Load(10, &q.messageCount)
+	stateSourceObject.Load(11, &q.maxBytes)
+	stateSourceObject.Load(12, &q.sendPID)
+	stateSourceObject.Load(13, &q.receivePID)
+}
+
+func (m *Message) StateTypeName() string {
+	return "pkg/sentry/kernel/msgqueue.Message"
+}
+
+func (m *Message) StateFields() []string {
+	return []string{
+		"msgEntry",
+		"mType",
+		"mText",
+		"mSize",
+	}
+}
+
+func (m *Message) beforeSave() {}
+
+// +checklocksignore
+func (m *Message) StateSave(stateSinkObject state.Sink) {
+	m.beforeSave()
+	stateSinkObject.Save(0, &m.msgEntry)
+	stateSinkObject.Save(1, &m.mType)
+	stateSinkObject.Save(2, &m.mText)
+	stateSinkObject.Save(3, &m.mSize)
+}
+
+func (m *Message) afterLoad() {}
+
+// +checklocksignore
+func (m *Message) StateLoad(stateSourceObject state.Source) {
+	stateSourceObject.Load(0, &m.msgEntry)
+	stateSourceObject.Load(1, &m.mType)
+	stateSourceObject.Load(2, &m.mText)
+	stateSourceObject.Load(3, &m.mSize)
+}
+
+func init() {
+	state.Register((*msgList)(nil))
+	state.Register((*msgEntry)(nil))
+	state.Register((*Registry)(nil))
+	state.Register((*Queue)(nil))
+	state.Register((*Message)(nil))
+}