257 lines
8.3 KiB
Go
257 lines
8.3 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package binder implements Android Binder IPC module.
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package binder
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import (
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"sync"
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
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"gvisor.googlesource.com/gvisor/pkg/sentry/memmap"
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"gvisor.googlesource.com/gvisor/pkg/sentry/pgalloc"
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"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usage"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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"gvisor.googlesource.com/gvisor/pkg/waiter"
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)
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const (
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currentProtocolVersion = 8
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// mmapSizeLimit is the upper limit for mapped memory size in Binder.
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mmapSizeLimit = 4 * 1024 * 1024 // 4MB
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)
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// Device implements fs.InodeOperations.
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//
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// +stateify savable
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type Device struct {
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fsutil.InodeGenericChecker `state:"nosave"`
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fsutil.InodeNoExtendedAttributes `state:"nosave"`
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fsutil.InodeNoopRelease `state:"nosave"`
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fsutil.InodeNoopTruncate `state:"nosave"`
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fsutil.InodeNoopWriteOut `state:"nosave"`
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fsutil.InodeNotDirectory `state:"nosave"`
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fsutil.InodeNotMappable `state:"nosave"`
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fsutil.InodeNotSocket `state:"nosave"`
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fsutil.InodeNotSymlink `state:"nosave"`
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fsutil.InodeVirtual `state:"nosave"`
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fsutil.InodeSimpleAttributes
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}
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var _ fs.InodeOperations = (*Device)(nil)
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// NewDevice creates and intializes a Device structure.
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func NewDevice(ctx context.Context, owner fs.FileOwner, fp fs.FilePermissions) *Device {
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return &Device{
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InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fp, 0),
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}
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}
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// GetFile implements fs.InodeOperations.GetFile.
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//
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// TODO: Add functionality to GetFile: Additional fields will be
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// needed in the Device structure, initialize them here. Also, Device will need
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// to keep track of the created Procs in order to implement BINDER_READ_WRITE
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// ioctl.
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func (bd *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
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return fs.NewFile(ctx, d, flags, &Proc{
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bd: bd,
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task: kernel.TaskFromContext(ctx),
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mfp: pgalloc.MemoryFileProviderFromContext(ctx),
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}), nil
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}
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// Proc implements fs.FileOperations and fs.IoctlGetter.
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//
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// +stateify savable
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type Proc struct {
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waiter.AlwaysReady `state:"nosave"`
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fsutil.FileNoFsync `state:"nosave"`
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fsutil.FileNotDirReaddir `state:"nosave"`
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bd *Device
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task *kernel.Task
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mfp pgalloc.MemoryFileProvider
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// mu protects fr.
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mu sync.Mutex `state:"nosave"`
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// mapped is memory allocated from mfp.MemoryFile() by AddMapping.
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mapped platform.FileRange
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}
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// Release implements fs.FileOperations.Release.
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func (bp *Proc) Release() {
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bp.mu.Lock()
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defer bp.mu.Unlock()
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if bp.mapped.Length() != 0 {
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bp.mfp.MemoryFile().DecRef(bp.mapped)
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}
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}
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// Seek implements fs.FileOperations.Seek.
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//
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// Binder doesn't support seek operation (unless in debug mode).
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func (bp *Proc) Seek(ctx context.Context, file *fs.File, whence fs.SeekWhence, offset int64) (int64, error) {
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return offset, syserror.EOPNOTSUPP
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}
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// Read implements fs.FileOperations.Read.
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//
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// Binder doesn't support read operation (unless in debug mode).
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func (bp *Proc) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
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return 0, syserror.EOPNOTSUPP
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}
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// Write implements fs.FileOperations.Write.
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//
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// Binder doesn't support write operation.
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func (bp *Proc) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
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return 0, syserror.EOPNOTSUPP
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}
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// Flush implements fs.FileOperations.Flush.
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//
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// TODO: Implement.
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func (bp *Proc) Flush(ctx context.Context, file *fs.File) error {
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return nil
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}
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// ConfigureMMap implements fs.FileOperations.ConfigureMMap.
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func (bp *Proc) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MMapOpts) error {
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// Compare drivers/android/binder.c:binder_mmap().
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if caller := kernel.TaskFromContext(ctx); caller != bp.task {
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return syserror.EINVAL
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}
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if opts.Length > mmapSizeLimit {
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opts.Length = mmapSizeLimit
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}
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opts.MaxPerms.Write = false
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// TODO: Binder sets VM_DONTCOPY, preventing the created vma
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// from being copied across fork(), but we don't support this yet. As
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// a result, MMs containing a Binder mapping cannot be forked (MM.Fork will
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// fail when AddMapping returns EBUSY).
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return fsutil.GenericConfigureMMap(file, bp, opts)
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}
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// Ioctl implements fs.FileOperations.Ioctl.
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//
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// TODO: Implement.
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func (bp *Proc) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
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// Switch on ioctl request.
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switch uint32(args[1].Int()) {
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case linux.BinderVersionIoctl:
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ver := &linux.BinderVersion{
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ProtocolVersion: currentProtocolVersion,
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}
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// Copy result to user-space.
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_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), ver, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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return 0, err
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case linux.BinderWriteReadIoctl:
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// TODO: Implement.
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fallthrough
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case linux.BinderSetIdleTimeoutIoctl:
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// TODO: Implement.
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fallthrough
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case linux.BinderSetMaxThreadsIoctl:
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// TODO: Implement.
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fallthrough
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case linux.BinderSetIdlePriorityIoctl:
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// TODO: Implement.
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fallthrough
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case linux.BinderSetContextMgrIoctl:
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// TODO: Implement.
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fallthrough
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case linux.BinderThreadExitIoctl:
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// TODO: Implement.
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return 0, syserror.ENOSYS
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default:
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// Ioctls irrelevant to Binder.
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return 0, syserror.EINVAL
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}
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}
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// AddMapping implements memmap.Mappable.AddMapping.
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func (bp *Proc) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, _ bool) error {
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bp.mu.Lock()
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defer bp.mu.Unlock()
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if bp.mapped.Length() != 0 {
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// mmap has been called before, which binder_mmap() doesn't like.
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return syserror.EBUSY
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}
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// Binder only allocates and maps a single page up-front
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// (drivers/android/binder.c:binder_mmap() => binder_update_page_range()).
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fr, err := bp.mfp.MemoryFile().Allocate(usermem.PageSize, usage.Anonymous)
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if err != nil {
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return err
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}
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bp.mapped = fr
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return nil
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}
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// RemoveMapping implements memmap.Mappable.RemoveMapping.
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func (*Proc) RemoveMapping(context.Context, memmap.MappingSpace, usermem.AddrRange, uint64, bool) {
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// Nothing to do. Notably, we don't free bp.mapped to allow another mmap.
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}
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// CopyMapping implements memmap.Mappable.CopyMapping.
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func (bp *Proc) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR usermem.AddrRange, offset uint64, _ bool) error {
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// Nothing to do. Notably, this is one case where CopyMapping isn't
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// equivalent to AddMapping, as AddMapping would return EBUSY.
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return nil
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}
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// Translate implements memmap.Mappable.Translate.
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func (bp *Proc) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) {
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// TODO: In addition to the page initially allocated and mapped
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// in AddMapping (Linux: binder_mmap), Binder allocates and maps pages for
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// each transaction (Linux: binder_ioctl => binder_ioctl_write_read =>
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// binder_thread_write => binder_transaction => binder_alloc_buf =>
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// binder_update_page_range). Since we don't actually implement
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// BinderWriteReadIoctl (Linux: BINDER_WRITE_READ), we only ever have the
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// first page.
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var err error
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if required.End > usermem.PageSize {
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err = &memmap.BusError{syserror.EFAULT}
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}
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if required.Start == 0 {
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return []memmap.Translation{
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{
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Source: memmap.MappableRange{0, usermem.PageSize},
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File: bp.mfp.MemoryFile(),
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Offset: bp.mapped.Start,
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},
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}, err
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}
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return nil, err
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}
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// InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
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func (bp *Proc) InvalidateUnsavable(ctx context.Context) error {
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return nil
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}
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