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-rwxr-xr-xpkg/sentry/vfs/device.go100
-rwxr-xr-xpkg/sentry/vfs/file_description.go101
-rwxr-xr-xpkg/sentry/vfs/file_description_impl_util.go15
-rwxr-xr-xpkg/sentry/vfs/filesystem.go21
-rwxr-xr-xpkg/sentry/vfs/vfs.go6
5 files changed, 235 insertions, 8 deletions
diff --git a/pkg/sentry/vfs/device.go b/pkg/sentry/vfs/device.go
new file mode 100755
index 000000000..cb672e36f
--- /dev/null
+++ b/pkg/sentry/vfs/device.go
@@ -0,0 +1,100 @@
+// Copyright 2019 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 vfs
+
+import (
+ "fmt"
+
+ "gvisor.dev/gvisor/pkg/sentry/context"
+ "gvisor.dev/gvisor/pkg/syserror"
+)
+
+// DeviceKind indicates whether a device is a block or character device.
+type DeviceKind uint32
+
+const (
+ // BlockDevice indicates a block device.
+ BlockDevice DeviceKind = iota
+
+ // CharDevice indicates a character device.
+ CharDevice
+)
+
+// String implements fmt.Stringer.String.
+func (kind DeviceKind) String() string {
+ switch kind {
+ case BlockDevice:
+ return "block"
+ case CharDevice:
+ return "character"
+ default:
+ return fmt.Sprintf("invalid device kind %d", kind)
+ }
+}
+
+type devTuple struct {
+ kind DeviceKind
+ major uint32
+ minor uint32
+}
+
+// A Device backs device special files.
+type Device interface {
+ // Open returns a FileDescription representing this device.
+ Open(ctx context.Context, mnt *Mount, d *Dentry, opts OpenOptions) (*FileDescription, error)
+}
+
+type registeredDevice struct {
+ dev Device
+ opts RegisterDeviceOptions
+}
+
+// RegisterDeviceOptions contains options to
+// VirtualFilesystem.RegisterDevice().
+type RegisterDeviceOptions struct {
+ // GroupName is the name shown for this device registration in
+ // /proc/devices. If GroupName is empty, this registration will not be
+ // shown in /proc/devices.
+ GroupName string
+}
+
+// RegisterDevice registers the given Device in vfs with the given major and
+// minor device numbers.
+func (vfs *VirtualFilesystem) RegisterDevice(kind DeviceKind, major, minor uint32, dev Device, opts *RegisterDeviceOptions) error {
+ tup := devTuple{kind, major, minor}
+ vfs.devicesMu.Lock()
+ defer vfs.devicesMu.Unlock()
+ if existing, ok := vfs.devices[tup]; ok {
+ return fmt.Errorf("%s device number (%d, %d) is already registered to device type %T", kind, major, minor, existing.dev)
+ }
+ vfs.devices[tup] = &registeredDevice{
+ dev: dev,
+ opts: *opts,
+ }
+ return nil
+}
+
+// OpenDeviceSpecialFile returns a FileDescription representing the given
+// device.
+func (vfs *VirtualFilesystem) OpenDeviceSpecialFile(ctx context.Context, mnt *Mount, d *Dentry, kind DeviceKind, major, minor uint32, opts *OpenOptions) (*FileDescription, error) {
+ tup := devTuple{kind, major, minor}
+ vfs.devicesMu.RLock()
+ defer vfs.devicesMu.RUnlock()
+ rd, ok := vfs.devices[tup]
+ if !ok {
+ return nil, syserror.ENXIO
+ }
+ return rd.dev.Open(ctx, mnt, d, *opts)
+}
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 0b053201a..6afe280bc 100755
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -61,11 +61,25 @@ type FileDescriptionOptions struct {
// If AllowDirectIO is true, allow O_DIRECT to be set on the file. This is
// usually only the case if O_DIRECT would actually have an effect.
AllowDirectIO bool
+
+ // If UseDentryMetadata is true, calls to FileDescription methods that
+ // interact with file and filesystem metadata (Stat, SetStat, StatFS,
+ // Listxattr, Getxattr, Setxattr, Removexattr) are implemented by calling
+ // the corresponding FilesystemImpl methods instead of the corresponding
+ // FileDescriptionImpl methods.
+ //
+ // UseDentryMetadata is intended for file descriptions that are implemented
+ // outside of individual filesystems, such as pipes, sockets, and device
+ // special files. FileDescriptions for which UseDentryMetadata is true may
+ // embed DentryMetadataFileDescriptionImpl to obtain appropriate
+ // implementations of FileDescriptionImpl methods that should not be
+ // called.
+ UseDentryMetadata bool
}
-// Init must be called before first use of fd. It takes ownership of references
-// on mnt and d held by the caller. statusFlags is the initial file description
-// status flags, which is usually the full set of flags passed to open(2).
+// Init must be called before first use of fd. It takes references on mnt and
+// d. statusFlags is the initial file description status flags, which is
+// usually the full set of flags passed to open(2).
func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mnt *Mount, d *Dentry, opts *FileDescriptionOptions) {
fd.refs = 1
fd.statusFlags = statusFlags | linux.O_LARGEFILE
@@ -73,6 +87,7 @@ func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mn
mount: mnt,
dentry: d,
}
+ fd.vd.IncRef()
fd.opts = *opts
fd.impl = impl
}
@@ -140,7 +155,7 @@ func (fd *FileDescription) SetStatusFlags(ctx context.Context, creds *auth.Crede
// sense. However, the check as actually implemented seems to be "O_APPEND
// cannot be changed if the file is marked as append-only".
if (flags^oldFlags)&linux.O_APPEND != 0 {
- stat, err := fd.impl.Stat(ctx, StatOptions{
+ stat, err := fd.Stat(ctx, StatOptions{
// There is no mask bit for stx_attributes.
Mask: 0,
// Linux just reads inode::i_flags directly.
@@ -154,7 +169,7 @@ func (fd *FileDescription) SetStatusFlags(ctx context.Context, creds *auth.Crede
}
}
if (flags&linux.O_NOATIME != 0) && (oldFlags&linux.O_NOATIME == 0) {
- stat, err := fd.impl.Stat(ctx, StatOptions{
+ stat, err := fd.Stat(ctx, StatOptions{
Mask: linux.STATX_UID,
// Linux's inode_owner_or_capable() just reads inode::i_uid
// directly.
@@ -348,17 +363,47 @@ func (fd *FileDescription) OnClose(ctx context.Context) error {
// Stat returns metadata for the file represented by fd.
func (fd *FileDescription) Stat(ctx context.Context, opts StatOptions) (linux.Statx, error) {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ stat, err := fd.vd.mount.fs.impl.StatAt(ctx, rp, opts)
+ vfsObj.putResolvingPath(rp)
+ return stat, err
+ }
return fd.impl.Stat(ctx, opts)
}
// SetStat updates metadata for the file represented by fd.
func (fd *FileDescription) SetStat(ctx context.Context, opts SetStatOptions) error {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ err := fd.vd.mount.fs.impl.SetStatAt(ctx, rp, opts)
+ vfsObj.putResolvingPath(rp)
+ return err
+ }
return fd.impl.SetStat(ctx, opts)
}
// StatFS returns metadata for the filesystem containing the file represented
// by fd.
func (fd *FileDescription) StatFS(ctx context.Context) (linux.Statfs, error) {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ statfs, err := fd.vd.mount.fs.impl.StatFSAt(ctx, rp)
+ vfsObj.putResolvingPath(rp)
+ return statfs, err
+ }
return fd.impl.StatFS(ctx)
}
@@ -417,6 +462,16 @@ func (fd *FileDescription) Ioctl(ctx context.Context, uio usermem.IO, args arch.
// Listxattr returns all extended attribute names for the file represented by
// fd.
func (fd *FileDescription) Listxattr(ctx context.Context) ([]string, error) {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ names, err := fd.vd.mount.fs.impl.ListxattrAt(ctx, rp)
+ vfsObj.putResolvingPath(rp)
+ return names, err
+ }
names, err := fd.impl.Listxattr(ctx)
if err == syserror.ENOTSUP {
// Linux doesn't actually return ENOTSUP in this case; instead,
@@ -431,18 +486,48 @@ func (fd *FileDescription) Listxattr(ctx context.Context) ([]string, error) {
// Getxattr returns the value associated with the given extended attribute for
// the file represented by fd.
func (fd *FileDescription) Getxattr(ctx context.Context, name string) (string, error) {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ val, err := fd.vd.mount.fs.impl.GetxattrAt(ctx, rp, name)
+ vfsObj.putResolvingPath(rp)
+ return val, err
+ }
return fd.impl.Getxattr(ctx, name)
}
// Setxattr changes the value associated with the given extended attribute for
// the file represented by fd.
func (fd *FileDescription) Setxattr(ctx context.Context, opts SetxattrOptions) error {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ err := fd.vd.mount.fs.impl.SetxattrAt(ctx, rp, opts)
+ vfsObj.putResolvingPath(rp)
+ return err
+ }
return fd.impl.Setxattr(ctx, opts)
}
// Removexattr removes the given extended attribute from the file represented
// by fd.
func (fd *FileDescription) Removexattr(ctx context.Context, name string) error {
+ if fd.opts.UseDentryMetadata {
+ vfsObj := fd.vd.mount.vfs
+ rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{
+ Root: fd.vd,
+ Start: fd.vd,
+ })
+ err := fd.vd.mount.fs.impl.RemovexattrAt(ctx, rp, name)
+ vfsObj.putResolvingPath(rp)
+ return err
+ }
return fd.impl.Removexattr(ctx, name)
}
@@ -464,7 +549,7 @@ func (fd *FileDescription) MappedName(ctx context.Context) string {
// DeviceID implements memmap.MappingIdentity.DeviceID.
func (fd *FileDescription) DeviceID() uint64 {
- stat, err := fd.impl.Stat(context.Background(), StatOptions{
+ stat, err := fd.Stat(context.Background(), StatOptions{
// There is no STATX_DEV; we assume that Stat will return it if it's
// available regardless of mask.
Mask: 0,
@@ -480,7 +565,7 @@ func (fd *FileDescription) DeviceID() uint64 {
// InodeID implements memmap.MappingIdentity.InodeID.
func (fd *FileDescription) InodeID() uint64 {
- stat, err := fd.impl.Stat(context.Background(), StatOptions{
+ stat, err := fd.Stat(context.Background(), StatOptions{
Mask: linux.STATX_INO,
// fs/proc/task_mmu.c:show_map_vma() just reads inode::i_ino directly.
Sync: linux.AT_STATX_DONT_SYNC,
@@ -493,5 +578,5 @@ func (fd *FileDescription) InodeID() uint64 {
// Msync implements memmap.MappingIdentity.Msync.
func (fd *FileDescription) Msync(ctx context.Context, mr memmap.MappableRange) error {
- return fd.impl.Sync(ctx)
+ return fd.Sync(ctx)
}
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index de782e577..66eb57bc2 100755
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -177,6 +177,21 @@ func (DirectoryFileDescriptionDefaultImpl) Write(ctx context.Context, src userme
return 0, syserror.EISDIR
}
+// DentryMetadataFileDescriptionImpl may be embedded by implementations of
+// FileDescriptionImpl for which FileDescriptionOptions.UseDentryMetadata is
+// true to obtain implementations of Stat and SetStat that panic.
+type DentryMetadataFileDescriptionImpl struct{}
+
+// Stat implements FileDescriptionImpl.Stat.
+func (DentryMetadataFileDescriptionImpl) Stat(ctx context.Context, opts StatOptions) (linux.Statx, error) {
+ panic("illegal call to DentryMetadataFileDescriptionImpl.Stat")
+}
+
+// SetStat implements FileDescriptionImpl.SetStat.
+func (DentryMetadataFileDescriptionImpl) SetStat(ctx context.Context, opts SetStatOptions) error {
+ panic("illegal call to DentryMetadataFileDescriptionImpl.SetStat")
+}
+
// DynamicBytesFileDescriptionImpl may be embedded by implementations of
// FileDescriptionImpl that represent read-only regular files whose contents
// are backed by a bytes.Buffer that is regenerated when necessary, consistent
diff --git a/pkg/sentry/vfs/filesystem.go b/pkg/sentry/vfs/filesystem.go
index 89bd58864..ea78f555b 100755
--- a/pkg/sentry/vfs/filesystem.go
+++ b/pkg/sentry/vfs/filesystem.go
@@ -418,17 +418,38 @@ type FilesystemImpl interface {
UnlinkAt(ctx context.Context, rp *ResolvingPath) error
// ListxattrAt returns all extended attribute names for the file at rp.
+ //
+ // Errors:
+ //
+ // - If extended attributes are not supported by the filesystem,
+ // ListxattrAt returns nil. (See FileDescription.Listxattr for an
+ // explanation.)
ListxattrAt(ctx context.Context, rp *ResolvingPath) ([]string, error)
// GetxattrAt returns the value associated with the given extended
// attribute for the file at rp.
+ //
+ // Errors:
+ //
+ // - If extended attributes are not supported by the filesystem, GetxattrAt
+ // returns ENOTSUP.
GetxattrAt(ctx context.Context, rp *ResolvingPath, name string) (string, error)
// SetxattrAt changes the value associated with the given extended
// attribute for the file at rp.
+ //
+ // Errors:
+ //
+ // - If extended attributes are not supported by the filesystem, SetxattrAt
+ // returns ENOTSUP.
SetxattrAt(ctx context.Context, rp *ResolvingPath, opts SetxattrOptions) error
// RemovexattrAt removes the given extended attribute from the file at rp.
+ //
+ // Errors:
+ //
+ // - If extended attributes are not supported by the filesystem,
+ // RemovexattrAt returns ENOTSUP.
RemovexattrAt(ctx context.Context, rp *ResolvingPath, name string) error
// PrependPath prepends a path from vd to vd.Mount().Root() to b.
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index a3bdb5805..ea2db7031 100755
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -75,6 +75,11 @@ type VirtualFilesystem struct {
// mountpoints is analogous to Linux's mountpoint_hashtable.
mountpoints map[*Dentry]map[*Mount]struct{}
+ // devices contains all registered Devices. devices is protected by
+ // devicesMu.
+ devicesMu sync.RWMutex
+ devices map[devTuple]*registeredDevice
+
// fsTypes contains all registered FilesystemTypes. fsTypes is protected by
// fsTypesMu.
fsTypesMu sync.RWMutex
@@ -90,6 +95,7 @@ type VirtualFilesystem struct {
func New() *VirtualFilesystem {
vfs := &VirtualFilesystem{
mountpoints: make(map[*Dentry]map[*Mount]struct{}),
+ devices: make(map[devTuple]*registeredDevice),
fsTypes: make(map[string]*registeredFilesystemType),
filesystems: make(map[*Filesystem]struct{}),
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-17 18:45:48 +0000