Merge pull request #6108 from sudo-sturbia:msgqueue/syscalls

PiperOrigin-RevId: 386323389

2 files changed, 256 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/msgqueue/BUILD b/pkg/sentry/kernel/msgqueue/BUILD
new file mode 100644
index 000000000..5ec11e1f6
--- /dev/null
+++ b/pkg/sentry/kernel/msgqueue/BUILD
@@ -0,0 +1,36 @@
+load("//tools:defs.bzl", "go_library")
+load("//tools/go_generics:defs.bzl", "go_template_instance")
+
+package(licenses = ["notice"])
+
+go_template_instance(
+    name = "message_list",
+    out = "message_list.go",
+    package = "msgqueue",
+    prefix = "msg",
+    template = "//pkg/ilist:generic_list",
+    types = {
+        "Element": "*Message",
+        "Linker": "*Message",
+    },
+)
+
+go_library(
+    name = "msgqueue",
+    srcs = [
+        "message_list.go",
+        "msgqueue.go",
+    ],
+    visibility = ["//pkg/sentry:internal"],
+    deps = [
+        "//pkg/abi/linux",
+        "//pkg/context",
+        "//pkg/errors/linuxerr",
+        "//pkg/sentry/fs",
+        "//pkg/sentry/kernel/auth",
+        "//pkg/sentry/kernel/ipc",
+        "//pkg/sentry/kernel/time",
+        "//pkg/sync",
+        "//pkg/waiter",
+    ],
+)
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
+}