diff options
Diffstat (limited to 'pkg/sentry/kernel/msgqueue')
-rw-r--r-- | pkg/sentry/kernel/msgqueue/BUILD | 36 | ||||
-rw-r--r-- | pkg/sentry/kernel/msgqueue/msgqueue.go | 220 |
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 +} |