From 8dcedc953a610b97efe9f68ac8fecf5e15a7e26b Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Wed, 29 Jan 2020 10:08:25 -0800 Subject: Add //pkg/sentry/devices/memdev. PiperOrigin-RevId: 292165063 --- pkg/abi/linux/dev.go | 3 ++ pkg/sentry/devices/memdev/BUILD | 28 +++++++++++ pkg/sentry/devices/memdev/full.go | 75 ++++++++++++++++++++++++++++++ pkg/sentry/devices/memdev/memdev.go | 59 ++++++++++++++++++++++++ pkg/sentry/devices/memdev/null.go | 76 ++++++++++++++++++++++++++++++ pkg/sentry/devices/memdev/random.go | 92 +++++++++++++++++++++++++++++++++++++ pkg/sentry/devices/memdev/zero.go | 88 +++++++++++++++++++++++++++++++++++ 7 files changed, 421 insertions(+) create mode 100644 pkg/sentry/devices/memdev/BUILD create mode 100644 pkg/sentry/devices/memdev/full.go create mode 100644 pkg/sentry/devices/memdev/memdev.go create mode 100644 pkg/sentry/devices/memdev/null.go create mode 100644 pkg/sentry/devices/memdev/random.go create mode 100644 pkg/sentry/devices/memdev/zero.go diff --git a/pkg/abi/linux/dev.go b/pkg/abi/linux/dev.go index 421e11256..89f9a793f 100644 --- a/pkg/abi/linux/dev.go +++ b/pkg/abi/linux/dev.go @@ -36,6 +36,9 @@ func DecodeDeviceID(rdev uint32) (uint16, uint32) { // // See Documentations/devices.txt and uapi/linux/major.h. const ( + // MEM_MAJOR is the major device number for "memory" character devices. + MEM_MAJOR = 1 + // TTYAUX_MAJOR is the major device number for alternate TTY devices. TTYAUX_MAJOR = 5 diff --git a/pkg/sentry/devices/memdev/BUILD b/pkg/sentry/devices/memdev/BUILD new file mode 100644 index 000000000..abe58f818 --- /dev/null +++ b/pkg/sentry/devices/memdev/BUILD @@ -0,0 +1,28 @@ +load("//tools:defs.bzl", "go_library") + +licenses(["notice"]) + +go_library( + name = "memdev", + srcs = [ + "full.go", + "memdev.go", + "null.go", + "random.go", + "zero.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/rand", + "//pkg/safemem", + "//pkg/sentry/fsimpl/devtmpfs", + "//pkg/sentry/memmap", + "//pkg/sentry/mm", + "//pkg/sentry/pgalloc", + "//pkg/sentry/vfs", + "//pkg/syserror", + "//pkg/usermem", + ], +) diff --git a/pkg/sentry/devices/memdev/full.go b/pkg/sentry/devices/memdev/full.go new file mode 100644 index 000000000..c7e197691 --- /dev/null +++ b/pkg/sentry/devices/memdev/full.go @@ -0,0 +1,75 @@ +// Copyright 2020 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 memdev + +import ( + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" +) + +const fullDevMinor = 7 + +// fullDevice implements vfs.Device for /dev/full. +type fullDevice struct{} + +// Open implements vfs.Device.Open. +func (fullDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd := &fullFD{} + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// fullFD implements vfs.FileDescriptionImpl for /dev/full. +type fullFD struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *fullFD) Release() { + // noop +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *fullFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + return dst.ZeroOut(ctx, dst.NumBytes()) +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *fullFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + return dst.ZeroOut(ctx, dst.NumBytes()) +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *fullFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + return 0, syserror.ENOSPC +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *fullFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + return 0, syserror.ENOSPC +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *fullFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + return 0, nil +} diff --git a/pkg/sentry/devices/memdev/memdev.go b/pkg/sentry/devices/memdev/memdev.go new file mode 100644 index 000000000..5759900c4 --- /dev/null +++ b/pkg/sentry/devices/memdev/memdev.go @@ -0,0 +1,59 @@ +// Copyright 2020 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 memdev implements "mem" character devices, as implemented in Linux +// by drivers/char/mem.c and drivers/char/random.c. +package memdev + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/devtmpfs" + "gvisor.dev/gvisor/pkg/sentry/vfs" +) + +// Register registers all devices implemented by this package in vfsObj. +func Register(vfsObj *vfs.VirtualFilesystem) error { + for minor, dev := range map[uint32]vfs.Device{ + nullDevMinor: nullDevice{}, + zeroDevMinor: zeroDevice{}, + fullDevMinor: fullDevice{}, + randomDevMinor: randomDevice{}, + urandomDevMinor: randomDevice{}, + } { + if err := vfsObj.RegisterDevice(vfs.CharDevice, linux.MEM_MAJOR, minor, dev, &vfs.RegisterDeviceOptions{ + GroupName: "mem", + }); err != nil { + return err + } + } + return nil +} + +// CreateDevtmpfsFiles creates device special files in dev representing all +// devices implemented by this package. +func CreateDevtmpfsFiles(ctx context.Context, dev *devtmpfs.Accessor) error { + for minor, name := range map[uint32]string{ + nullDevMinor: "null", + zeroDevMinor: "zero", + fullDevMinor: "full", + randomDevMinor: "random", + urandomDevMinor: "urandom", + } { + if err := dev.CreateDeviceFile(ctx, name, vfs.CharDevice, linux.MEM_MAJOR, minor, 0666 /* mode */); err != nil { + return err + } + } + return nil +} diff --git a/pkg/sentry/devices/memdev/null.go b/pkg/sentry/devices/memdev/null.go new file mode 100644 index 000000000..33d060d02 --- /dev/null +++ b/pkg/sentry/devices/memdev/null.go @@ -0,0 +1,76 @@ +// Copyright 2020 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 memdev + +import ( + "io" + + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/usermem" +) + +const nullDevMinor = 3 + +// nullDevice implements vfs.Device for /dev/null. +type nullDevice struct{} + +// Open implements vfs.Device.Open. +func (nullDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd := &nullFD{} + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// nullFD implements vfs.FileDescriptionImpl for /dev/null. +type nullFD struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *nullFD) Release() { + // noop +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *nullFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + return 0, io.EOF +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *nullFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + return 0, io.EOF +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *nullFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + return src.NumBytes(), nil +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *nullFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + return src.NumBytes(), nil +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *nullFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + return 0, nil +} diff --git a/pkg/sentry/devices/memdev/random.go b/pkg/sentry/devices/memdev/random.go new file mode 100644 index 000000000..acfa23149 --- /dev/null +++ b/pkg/sentry/devices/memdev/random.go @@ -0,0 +1,92 @@ +// Copyright 2020 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 memdev + +import ( + "sync/atomic" + + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/rand" + "gvisor.dev/gvisor/pkg/safemem" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/usermem" +) + +const ( + randomDevMinor = 8 + urandomDevMinor = 9 +) + +// randomDevice implements vfs.Device for /dev/random and /dev/urandom. +type randomDevice struct{} + +// Open implements vfs.Device.Open. +func (randomDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd := &randomFD{} + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// randomFD implements vfs.FileDescriptionImpl for /dev/random. +type randomFD struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl + + // off is the "file offset". off is accessed using atomic memory + // operations. + off int64 +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *randomFD) Release() { + // noop +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *randomFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + return dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader}) +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *randomFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + n, err := dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader}) + atomic.AddInt64(&fd.off, n) + return n, err +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *randomFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + // In Linux, this mixes the written bytes into the entropy pool; we just + // throw them away. + return src.NumBytes(), nil +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *randomFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + atomic.AddInt64(&fd.off, src.NumBytes()) + return src.NumBytes(), nil +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *randomFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + // Linux: drivers/char/random.c:random_fops.llseek == urandom_fops.llseek + // == noop_llseek + return atomic.LoadInt64(&fd.off), nil +} diff --git a/pkg/sentry/devices/memdev/zero.go b/pkg/sentry/devices/memdev/zero.go new file mode 100644 index 000000000..3b1372b9e --- /dev/null +++ b/pkg/sentry/devices/memdev/zero.go @@ -0,0 +1,88 @@ +// Copyright 2020 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 memdev + +import ( + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/memmap" + "gvisor.dev/gvisor/pkg/sentry/mm" + "gvisor.dev/gvisor/pkg/sentry/pgalloc" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/usermem" +) + +const zeroDevMinor = 5 + +// zeroDevice implements vfs.Device for /dev/zero. +type zeroDevice struct{} + +// Open implements vfs.Device.Open. +func (zeroDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd := &zeroFD{} + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// zeroFD implements vfs.FileDescriptionImpl for /dev/zero. +type zeroFD struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *zeroFD) Release() { + // noop +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *zeroFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + return dst.ZeroOut(ctx, dst.NumBytes()) +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *zeroFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + return dst.ZeroOut(ctx, dst.NumBytes()) +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *zeroFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + return src.NumBytes(), nil +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *zeroFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + return src.NumBytes(), nil +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *zeroFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + return 0, nil +} + +// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. +func (fd *zeroFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error { + m, err := mm.NewSharedAnonMappable(opts.Length, pgalloc.MemoryFileProviderFromContext(ctx)) + if err != nil { + return err + } + opts.MappingIdentity = m + opts.Mappable = m + return nil +} -- cgit v1.2.3