diff options
Diffstat (limited to 'pkg/sentry')
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/BUILD | 4 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/dev.go | 28 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/fuse/fusefs.go | 200 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/vfs2/mount.go | 9 | ||||
| -rw-r--r-- | pkg/sentry/vfs/options.go | 11 |
5 files changed, 250 insertions, 2 deletions
diff --git a/pkg/sentry/fsimpl/fuse/BUILD b/pkg/sentry/fsimpl/fuse/BUILD index 3e00c2abb..737007748 100644 --- a/pkg/sentry/fsimpl/fuse/BUILD +++ b/pkg/sentry/fsimpl/fuse/BUILD @@ -6,13 +6,17 @@ go_library( name = "fuse", srcs = [ "dev.go", + "fusefs.go", ], visibility = ["//pkg/sentry:internal"], deps = [ "//pkg/abi/linux", "//pkg/context", + "//pkg/log", "//pkg/sentry/fsimpl/devtmpfs", + "//pkg/sentry/fsimpl/kernfs", "//pkg/sentry/kernel", + "//pkg/sentry/kernel/auth", "//pkg/sentry/vfs", "//pkg/syserror", "//pkg/usermem", diff --git a/pkg/sentry/fsimpl/fuse/dev.go b/pkg/sentry/fsimpl/fuse/dev.go index dc33268af..c9e12a94f 100644 --- a/pkg/sentry/fsimpl/fuse/dev.go +++ b/pkg/sentry/fsimpl/fuse/dev.go @@ -51,6 +51,9 @@ type DeviceFD struct { vfs.DentryMetadataFileDescriptionImpl vfs.NoLockFD + // mounted specifies whether a FUSE filesystem was mounted using the DeviceFD. + mounted bool + // TODO(gvisor.dev/issue/2987): Add all the data structures needed to enqueue // and deque requests, control synchronization and establish communication // between the FUSE kernel module and the /dev/fuse character device. @@ -61,26 +64,51 @@ func (fd *DeviceFD) Release() {} // PRead implements vfs.FileDescriptionImpl.PRead. func (fd *DeviceFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + return 0, syserror.ENOSYS } // Read implements vfs.FileDescriptionImpl.Read. func (fd *DeviceFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + return 0, syserror.ENOSYS } // PWrite implements vfs.FileDescriptionImpl.PWrite. func (fd *DeviceFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + return 0, syserror.ENOSYS } // Write implements vfs.FileDescriptionImpl.Write. func (fd *DeviceFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + return 0, syserror.ENOSYS } // Seek implements vfs.FileDescriptionImpl.Seek. func (fd *DeviceFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + return 0, syserror.ENOSYS } diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go new file mode 100644 index 000000000..f7775fb9b --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/fusefs.go @@ -0,0 +1,200 @@ +// 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 fuse implements fusefs. +package fuse + +import ( + "strconv" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Name is the default filesystem name. +const Name = "fuse" + +// FilesystemType implements vfs.FilesystemType. +type FilesystemType struct{} + +type filesystemOptions struct { + // userID specifies the numeric uid of the mount owner. + // This option should not be specified by the filesystem owner. + // It is set by libfuse (or, if libfuse is not used, must be set + // by the filesystem itself). For more information, see man page + // for fuse(8) + userID uint32 + + // groupID specifies the numeric gid of the mount owner. + // This option should not be specified by the filesystem owner. + // It is set by libfuse (or, if libfuse is not used, must be set + // by the filesystem itself). For more information, see man page + // for fuse(8) + groupID uint32 + + // rootMode specifies the the file mode of the filesystem's root. + rootMode linux.FileMode +} + +// filesystem implements vfs.FilesystemImpl. +type filesystem struct { + kernfs.Filesystem + devMinor uint32 + + // fuseFD is the FD returned when opening /dev/fuse. It is used for communication + // between the FUSE server daemon and the sentry fusefs. + fuseFD *DeviceFD + + // opts is the options the fusefs is initialized with. + opts filesystemOptions +} + +// Name implements vfs.FilesystemType.Name. +func (FilesystemType) Name() string { + return Name +} + +// GetFilesystem implements vfs.FilesystemType.GetFilesystem. +func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) { + devMinor, err := vfsObj.GetAnonBlockDevMinor() + if err != nil { + return nil, nil, err + } + + var fsopts filesystemOptions + mopts := vfs.GenericParseMountOptions(opts.Data) + deviceDescriptorStr, ok := mopts["fd"] + if !ok { + log.Warningf("%s.GetFilesystem: communication file descriptor N (obtained by opening /dev/fuse) must be specified as 'fd=N'", fsType.Name()) + return nil, nil, syserror.EINVAL + } + delete(mopts, "fd") + + deviceDescriptor, err := strconv.ParseInt(deviceDescriptorStr, 10 /* base */, 32 /* bitSize */) + if err != nil { + return nil, nil, err + } + + kernelTask := kernel.TaskFromContext(ctx) + if kernelTask == nil { + log.Warningf("%s.GetFilesystem: couldn't get kernel task from context", fsType.Name()) + return nil, nil, syserror.EINVAL + } + fuseFd := kernelTask.GetFileVFS2(int32(deviceDescriptor)) + + // Parse and set all the other supported FUSE mount options. + // TODO: Expand the supported mount options. + if userIDStr, ok := mopts["user_id"]; ok { + delete(mopts, "user_id") + userID, err := strconv.ParseUint(userIDStr, 10, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid user_id: user_id=%s", fsType.Name(), userIDStr) + return nil, nil, syserror.EINVAL + } + fsopts.userID = uint32(userID) + } + + if groupIDStr, ok := mopts["group_id"]; ok { + delete(mopts, "group_id") + groupID, err := strconv.ParseUint(groupIDStr, 10, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid group_id: group_id=%s", fsType.Name(), groupIDStr) + return nil, nil, syserror.EINVAL + } + fsopts.groupID = uint32(groupID) + } + + rootMode := linux.FileMode(0777) + modeStr, ok := mopts["rootmode"] + if ok { + delete(mopts, "rootmode") + mode, err := strconv.ParseUint(modeStr, 8, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid mode: %q", fsType.Name(), modeStr) + return nil, nil, syserror.EINVAL + } + rootMode = linux.FileMode(mode) + } + fsopts.rootMode = rootMode + + // Check for unparsed options. + if len(mopts) != 0 { + log.Warningf("%s.GetFilesystem: unknown options: %v", fsType.Name(), mopts) + return nil, nil, syserror.EINVAL + } + + // Mark the device as ready so it can be used. /dev/fuse can only be used if the FD was used to + // mount a FUSE filesystem. + fuseFD := fuseFd.Impl().(*DeviceFD) + fuseFD.mounted = true + + fs := &filesystem{ + devMinor: devMinor, + fuseFD: fuseFD, + opts: fsopts, + } + + fs.VFSFilesystem().Init(vfsObj, &fsType, fs) + + // TODO: dispatch a FUSE_INIT request to the FUSE daemon server before + // returning. Mount will not block on this dispatched request. + + // root is the fusefs root directory. + root := fs.newInode(creds, fsopts.rootMode) + + return fs.VFSFilesystem(), root.VFSDentry(), nil +} + +// Release implements vfs.FilesystemImpl.Release. +func (fs *filesystem) Release() { + fs.Filesystem.VFSFilesystem().VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor) + fs.Filesystem.Release() +} + +// Inode implements kernfs.Inode. +type Inode struct { + kernfs.InodeAttrs + kernfs.InodeNoDynamicLookup + kernfs.InodeNotSymlink + kernfs.InodeDirectoryNoNewChildren + kernfs.OrderedChildren + + locks vfs.FileLocks + + dentry kernfs.Dentry +} + +func (fs *filesystem) newInode(creds *auth.Credentials, mode linux.FileMode) *kernfs.Dentry { + i := &Inode{} + i.InodeAttrs.Init(creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0755) + i.OrderedChildren.Init(kernfs.OrderedChildrenOptions{}) + i.dentry.Init(i) + + return &i.dentry +} + +// Open implements kernfs.Inode.Open. +func (i *Inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) + if err != nil { + return nil, err + } + return fd.VFSFileDescription(), nil +} diff --git a/pkg/sentry/syscalls/linux/vfs2/mount.go b/pkg/sentry/syscalls/linux/vfs2/mount.go index adeaa39cc..ea337de7c 100644 --- a/pkg/sentry/syscalls/linux/vfs2/mount.go +++ b/pkg/sentry/syscalls/linux/vfs2/mount.go @@ -77,8 +77,7 @@ func Mount(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall // Silently allow MS_NOSUID, since we don't implement set-id bits // anyway. - const unsupportedFlags = linux.MS_NODEV | - linux.MS_NODIRATIME | linux.MS_STRICTATIME + const unsupportedFlags = linux.MS_NODIRATIME | linux.MS_STRICTATIME // Linux just allows passing any flags to mount(2) - it won't fail when // unknown or unsupported flags are passed. Since we don't implement @@ -94,6 +93,12 @@ func Mount(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall if flags&linux.MS_NOEXEC == linux.MS_NOEXEC { opts.Flags.NoExec = true } + if flags&linux.MS_NODEV == linux.MS_NODEV { + opts.Flags.NoDev = true + } + if flags&linux.MS_NOSUID == linux.MS_NOSUID { + opts.Flags.NoSUID = true + } if flags&linux.MS_RDONLY == linux.MS_RDONLY { opts.ReadOnly = true } diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go index f223aeda8..d37208a1f 100644 --- a/pkg/sentry/vfs/options.go +++ b/pkg/sentry/vfs/options.go @@ -79,6 +79,17 @@ type MountFlags struct { // NoATime is equivalent to MS_NOATIME and indicates that the // filesystem should not update access time in-place. NoATime bool + + // NoDev is equivalent to MS_NODEV and indicates that the + // filesystem should not allow access to devices (special files). + // TODO(gVisor.dev/issue/3186): respect this flag in non FUSE + // filesystems. + NoDev bool + + // NoSUID is equivalent to MS_NOSUID and indicates that the + // filesystem should not honor set-user-ID and set-group-ID bits or + // file capabilities when executing programs. + NoSUID bool } // MountOptions contains options to VirtualFilesystem.MountAt(). |