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// 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 linux
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/marshal/primitive"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/kernel/ipc"
"gvisor.dev/gvisor/pkg/sentry/kernel/msgqueue"
)
// Msgget implements msgget(2).
func Msgget(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
key := ipc.Key(args[0].Int())
flag := args[1].Int()
private := key == linux.IPC_PRIVATE
create := flag&linux.IPC_CREAT == linux.IPC_CREAT
exclusive := flag&linux.IPC_EXCL == linux.IPC_EXCL
mode := linux.FileMode(flag & 0777)
r := t.IPCNamespace().MsgqueueRegistry()
queue, err := r.FindOrCreate(t, key, mode, private, create, exclusive)
if err != nil {
return 0, nil, err
}
return uintptr(queue.ID()), nil, nil
}
// Msgsnd implements msgsnd(2).
func Msgsnd(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := ipc.ID(args[0].Int())
msgAddr := args[1].Pointer()
size := args[2].Int64()
flag := args[3].Int()
if size < 0 || size > linux.MSGMAX {
return 0, nil, linuxerr.EINVAL
}
wait := flag&linux.IPC_NOWAIT != linux.IPC_NOWAIT
pid := int32(t.ThreadGroup().ID())
buf := linux.MsgBuf{
Text: make([]byte, size),
}
if _, err := buf.CopyIn(t, msgAddr); err != nil {
return 0, nil, err
}
queue, err := t.IPCNamespace().MsgqueueRegistry().FindByID(id)
if err != nil {
return 0, nil, err
}
msg := msgqueue.Message{
Type: int64(buf.Type),
Text: buf.Text,
Size: uint64(size),
}
return 0, nil, queue.Send(t, msg, t, wait, pid)
}
// Msgrcv implements msgrcv(2).
func Msgrcv(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := ipc.ID(args[0].Int())
msgAddr := args[1].Pointer()
size := args[2].Int64()
mType := args[3].Int64()
flag := args[4].Int()
wait := flag&linux.IPC_NOWAIT != linux.IPC_NOWAIT
except := flag&linux.MSG_EXCEPT == linux.MSG_EXCEPT
truncate := flag&linux.MSG_NOERROR == linux.MSG_NOERROR
msgCopy := flag&linux.MSG_COPY == linux.MSG_COPY
msg, err := receive(t, id, mType, size, msgCopy, wait, truncate, except)
if err != nil {
return 0, nil, err
}
buf := linux.MsgBuf{
Type: primitive.Int64(msg.Type),
Text: msg.Text,
}
if _, err := buf.CopyOut(t, msgAddr); err != nil {
return 0, nil, err
}
return uintptr(msg.Size), nil, nil
}
// receive returns a message from the queue with the given ID. If msgCopy is
// true, a message is copied from the queue without being removed. Otherwise,
// a message is removed from the queue and returned.
func receive(t *kernel.Task, id ipc.ID, mType int64, maxSize int64, msgCopy, wait, truncate, except bool) (*msgqueue.Message, error) {
pid := int32(t.ThreadGroup().ID())
queue, err := t.IPCNamespace().MsgqueueRegistry().FindByID(id)
if err != nil {
return nil, err
}
if msgCopy {
if wait || except {
return nil, linuxerr.EINVAL
}
return queue.Copy(mType)
}
return queue.Receive(t, t, mType, maxSize, wait, truncate, except, pid)
}
// Msgctl implements msgctl(2).
func Msgctl(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := ipc.ID(args[0].Int())
cmd := args[1].Int()
buf := args[2].Pointer()
creds := auth.CredentialsFromContext(t)
r := t.IPCNamespace().MsgqueueRegistry()
switch cmd {
case linux.IPC_INFO:
info := r.IPCInfo(t)
_, err := info.CopyOut(t, buf)
return 0, nil, err
case linux.MSG_INFO:
msgInfo := r.MsgInfo(t)
_, err := msgInfo.CopyOut(t, buf)
return 0, nil, err
case linux.IPC_RMID:
return 0, nil, r.Remove(id, creds)
}
// Remaining commands use a queue.
queue, err := r.FindByID(id)
if err != nil {
return 0, nil, err
}
switch cmd {
case linux.MSG_STAT:
// Technically, we should be treating id as "an index into the kernel's
// internal array that maintains information about all shared memory
// segments on the system". Since we don't track segments in an array,
// we'll just pretend the msqid is the index and do the same thing as
// IPC_STAT. Linux also uses the index as the msqid.
fallthrough
case linux.IPC_STAT:
stat, err := queue.Stat(t)
if err != nil {
return 0, nil, err
}
_, err = stat.CopyOut(t, buf)
return 0, nil, err
case linux.MSG_STAT_ANY:
stat, err := queue.StatAny(t)
if err != nil {
return 0, nil, err
}
_, err = stat.CopyOut(t, buf)
return 0, nil, err
case linux.IPC_SET:
var ds linux.MsqidDS
if _, err := ds.CopyIn(t, buf); err != nil {
return 0, nil, linuxerr.EINVAL
}
err := queue.Set(t, &ds)
return 0, nil, err
default:
return 0, nil, linuxerr.EINVAL
}
}
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