From 18a7e1309decb9bc09879e337adbc00f81d420c5 Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Fri, 24 Jan 2020 17:06:30 -0800 Subject: [PATCH] Add support for device special files to VFS2 tmpfs. PiperOrigin-RevId: 291471892 --- pkg/sentry/fsimpl/tmpfs/BUILD | 1 + pkg/sentry/fsimpl/tmpfs/device_file.go | 39 +++++++++++++++++++++++ pkg/sentry/fsimpl/tmpfs/filesystem.go | 43 ++++++++++++++------------ pkg/sentry/fsimpl/tmpfs/tmpfs.go | 30 ++++++++++++++---- 4 files changed, 88 insertions(+), 25 deletions(-) create mode 100644 pkg/sentry/fsimpl/tmpfs/device_file.go diff --git a/pkg/sentry/fsimpl/tmpfs/BUILD b/pkg/sentry/fsimpl/tmpfs/BUILD index 7601c7c04..691476b4f 100644 --- a/pkg/sentry/fsimpl/tmpfs/BUILD +++ b/pkg/sentry/fsimpl/tmpfs/BUILD @@ -20,6 +20,7 @@ go_library( name = "tmpfs", srcs = [ "dentry_list.go", + "device_file.go", "directory.go", "filesystem.go", "named_pipe.go", diff --git a/pkg/sentry/fsimpl/tmpfs/device_file.go b/pkg/sentry/fsimpl/tmpfs/device_file.go new file mode 100644 index 000000000..84b181b90 --- /dev/null +++ b/pkg/sentry/fsimpl/tmpfs/device_file.go @@ -0,0 +1,39 @@ +// 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 tmpfs + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" +) + +type deviceFile struct { + inode inode + kind vfs.DeviceKind + major uint32 + minor uint32 +} + +func (fs *filesystem) newDeviceFile(creds *auth.Credentials, mode linux.FileMode, kind vfs.DeviceKind, major, minor uint32) *inode { + file := &deviceFile{ + kind: kind, + major: major, + minor: minor, + } + file.inode.init(file, fs, creds, mode) + file.inode.nlink = 1 // from parent directory + return &file.inode +} diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go index a9f66a42a..d726f03c5 100644 --- a/pkg/sentry/fsimpl/tmpfs/filesystem.go +++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go @@ -228,23 +228,26 @@ func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v // MknodAt implements vfs.FilesystemImpl.MknodAt. func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { return fs.doCreateAt(rp, false /* dir */, func(parent *dentry, name string) error { + var childInode *inode switch opts.Mode.FileType() { case 0, linux.S_IFREG: - child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode)) - parent.vfsd.InsertChild(&child.vfsd, name) - parent.inode.impl.(*directory).childList.PushBack(child) - return nil + childInode = fs.newRegularFile(rp.Credentials(), opts.Mode) case linux.S_IFIFO: - child := fs.newDentry(fs.newNamedPipe(rp.Credentials(), opts.Mode)) - parent.vfsd.InsertChild(&child.vfsd, name) - parent.inode.impl.(*directory).childList.PushBack(child) - return nil - case linux.S_IFBLK, linux.S_IFCHR, linux.S_IFSOCK: + childInode = fs.newNamedPipe(rp.Credentials(), opts.Mode) + case linux.S_IFBLK: + childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.BlockDevice, opts.DevMajor, opts.DevMinor) + case linux.S_IFCHR: + childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.CharDevice, opts.DevMajor, opts.DevMinor) + case linux.S_IFSOCK: // Not yet supported. return syserror.EPERM default: return syserror.EINVAL } + child := fs.newDentry(childInode) + parent.vfsd.InsertChild(&child.vfsd, name) + parent.inode.impl.(*directory).childList.PushBack(child) + return nil }) } @@ -264,7 +267,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf if err != nil { return nil, err } - return d.open(ctx, rp, opts.Flags, false /* afterCreate */) + return d.open(ctx, rp, &opts, false /* afterCreate */) } mustCreate := opts.Flags&linux.O_EXCL != 0 @@ -279,7 +282,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf if mustCreate { return nil, syserror.EEXIST } - return start.open(ctx, rp, opts.Flags, false /* afterCreate */) + return start.open(ctx, rp, &opts, false /* afterCreate */) } afterTrailingSymlink: parent, err := walkParentDirLocked(rp, start) @@ -313,7 +316,7 @@ afterTrailingSymlink: child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode)) parent.vfsd.InsertChild(&child.vfsd, name) parent.inode.impl.(*directory).childList.PushBack(child) - return child.open(ctx, rp, opts.Flags, true) + return child.open(ctx, rp, &opts, true) } if err != nil { return nil, err @@ -327,11 +330,11 @@ afterTrailingSymlink: if mustCreate { return nil, syserror.EEXIST } - return child.open(ctx, rp, opts.Flags, false) + return child.open(ctx, rp, &opts, false) } -func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32, afterCreate bool) (*vfs.FileDescription, error) { - ats := vfs.AccessTypesForOpenFlags(flags) +func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions, afterCreate bool) (*vfs.FileDescription, error) { + ats := vfs.AccessTypesForOpenFlags(opts.Flags) if !afterCreate { if err := d.inode.checkPermissions(rp.Credentials(), ats, d.inode.isDir()); err != nil { return nil, err @@ -340,10 +343,10 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32, switch impl := d.inode.impl.(type) { case *regularFile: var fd regularFileFD - if err := fd.vfsfd.Init(&fd, flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } - if flags&linux.O_TRUNC != 0 { + if opts.Flags&linux.O_TRUNC != 0 { impl.mu.Lock() impl.data.Truncate(0, impl.memFile) atomic.StoreUint64(&impl.size, 0) @@ -356,7 +359,7 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32, return nil, syserror.EISDIR } var fd directoryFD - if err := fd.vfsfd.Init(&fd, flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } return &fd.vfsfd, nil @@ -364,7 +367,9 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32, // Can't open symlinks without O_PATH (which is unimplemented). return nil, syserror.ELOOP case *namedPipe: - return newNamedPipeFD(ctx, impl, rp, &d.vfsd, flags) + return newNamedPipeFD(ctx, impl, rp, &d.vfsd, opts.Flags) + case *deviceFile: + return rp.VirtualFilesystem().OpenDeviceSpecialFile(ctx, rp.Mount(), &d.vfsd, impl.kind, impl.major, impl.minor, opts) default: panic(fmt.Sprintf("unknown inode type: %T", d.inode.impl)) } diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go index 1d4889c89..515f033f2 100644 --- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go +++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go @@ -149,6 +149,10 @@ type inode struct { ctime int64 // nanoseconds mtime int64 // nanoseconds + // Only meaningful for device special files. + rdevMajor uint32 + rdevMinor uint32 + impl interface{} // immutable } @@ -269,6 +273,15 @@ func (i *inode) statTo(stat *linux.Statx) { stat.Blocks = allocatedBlocksForSize(stat.Size) case *namedPipe: stat.Mode |= linux.S_IFIFO + case *deviceFile: + switch impl.kind { + case vfs.BlockDevice: + stat.Mode |= linux.S_IFBLK + case vfs.CharDevice: + stat.Mode |= linux.S_IFCHR + } + stat.RdevMajor = impl.major + stat.RdevMinor = impl.minor default: panic(fmt.Sprintf("unknown inode type: %T", i.impl)) } @@ -309,12 +322,8 @@ func (i *inode) setStat(stat linux.Statx) error { } case *directory: return syserror.EISDIR - case *symlink: - return syserror.EINVAL - case *namedPipe: - // Nothing. default: - panic(fmt.Sprintf("unknown inode type: %T", i.impl)) + return syserror.EINVAL } } if mask&linux.STATX_ATIME != 0 { @@ -353,13 +362,22 @@ func allocatedBlocksForSize(size uint64) uint64 { } func (i *inode) direntType() uint8 { - switch i.impl.(type) { + switch impl := i.impl.(type) { case *regularFile: return linux.DT_REG case *directory: return linux.DT_DIR case *symlink: return linux.DT_LNK + case *deviceFile: + switch impl.kind { + case vfs.BlockDevice: + return linux.DT_BLK + case vfs.CharDevice: + return linux.DT_CHR + default: + panic(fmt.Sprintf("unknown vfs.DeviceKind: %v", impl.kind)) + } default: panic(fmt.Sprintf("unknown inode type: %T", i.impl)) }