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-rw-r--r--pkg/sentry/kernel/msgqueue/BUILD36
-rw-r--r--pkg/sentry/kernel/msgqueue/msgqueue.go220
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
+}