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// Copyright 2018 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/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/ipc"
"gvisor.dev/gvisor/pkg/sentry/kernel/shm"
)
// Shmget implements shmget(2).
func Shmget(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
key := ipc.Key(args[0].Int())
size := uint64(args[1].SizeT())
flag := args[2].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)
pid := int32(t.ThreadGroup().ID())
r := t.IPCNamespace().ShmRegistry()
segment, err := r.FindOrCreate(t, pid, key, size, mode, private, create, exclusive)
if err != nil {
return 0, nil, err
}
defer segment.DecRef(t)
return uintptr(segment.ID()), nil, nil
}
// findSegment retrieves a shm segment by the given id.
//
// findSegment returns a reference on Shm.
func findSegment(t *kernel.Task, id ipc.ID) (*shm.Shm, error) {
r := t.IPCNamespace().ShmRegistry()
segment := r.FindByID(id)
if segment == nil {
// No segment with provided id.
return nil, linuxerr.EINVAL
}
return segment, nil
}
// Shmat implements shmat(2).
func Shmat(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := ipc.ID(args[0].Int())
addr := args[1].Pointer()
flag := args[2].Int()
segment, err := findSegment(t, id)
if err != nil {
return 0, nil, linuxerr.EINVAL
}
defer segment.DecRef(t)
opts, err := segment.ConfigureAttach(t, addr, shm.AttachOpts{
Execute: flag&linux.SHM_EXEC == linux.SHM_EXEC,
Readonly: flag&linux.SHM_RDONLY == linux.SHM_RDONLY,
Remap: flag&linux.SHM_REMAP == linux.SHM_REMAP,
})
if err != nil {
return 0, nil, err
}
addr, err = t.MemoryManager().MMap(t, opts)
return uintptr(addr), nil, err
}
// Shmdt implements shmdt(2).
func Shmdt(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
err := t.MemoryManager().DetachShm(t, addr)
return 0, nil, err
}
// Shmctl implements shmctl(2).
func Shmctl(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()
r := t.IPCNamespace().ShmRegistry()
switch cmd {
case linux.SHM_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 shmid is the index and do the same thing as
// IPC_STAT. Linux also uses the index as the shmid.
fallthrough
case linux.IPC_STAT:
segment, err := findSegment(t, id)
if err != nil {
return 0, nil, linuxerr.EINVAL
}
defer segment.DecRef(t)
stat, err := segment.IPCStat(t)
if err == nil {
_, err = stat.CopyOut(t, buf)
}
return 0, nil, err
case linux.IPC_INFO:
params := r.IPCInfo()
_, err := params.CopyOut(t, buf)
return 0, nil, err
case linux.SHM_INFO:
info := r.ShmInfo()
_, err := info.CopyOut(t, buf)
return 0, nil, err
}
// Remaining commands refer to a specific segment.
segment, err := findSegment(t, id)
if err != nil {
return 0, nil, linuxerr.EINVAL
}
defer segment.DecRef(t)
switch cmd {
case linux.IPC_SET:
var ds linux.ShmidDS
if _, err = ds.CopyIn(t, buf); err != nil {
return 0, nil, err
}
err := segment.Set(t, &ds)
return 0, nil, err
case linux.IPC_RMID:
segment.MarkDestroyed(t)
return 0, nil, nil
case linux.SHM_LOCK, linux.SHM_UNLOCK:
// We currently do not support memory locking anywhere.
// mlock(2)/munlock(2) are currently stubbed out as no-ops so do the
// same here.
t.Kernel().EmitUnimplementedEvent(t, sysno)
return 0, nil, nil
default:
return 0, nil, linuxerr.EINVAL
}
}
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