diff options
| -rw-r--r-- | pkg/sentry/vfs/device.go | 29 | ||||
| -rw-r--r-- | pkg/sentry/vfs/vfs.go | 18 |
2 files changed, 43 insertions, 4 deletions
diff --git a/pkg/sentry/vfs/device.go b/pkg/sentry/vfs/device.go index cb672e36f..9f9d6e783 100644 --- a/pkg/sentry/vfs/device.go +++ b/pkg/sentry/vfs/device.go @@ -98,3 +98,32 @@ func (vfs *VirtualFilesystem) OpenDeviceSpecialFile(ctx context.Context, mnt *Mo } return rd.dev.Open(ctx, mnt, d, *opts) } + +// GetAnonBlockDevMinor allocates and returns an unused minor device number for +// an "anonymous" block device with major number 0. +func (vfs *VirtualFilesystem) GetAnonBlockDevMinor() (uint32, error) { + vfs.anonBlockDevMinorMu.Lock() + defer vfs.anonBlockDevMinorMu.Unlock() + minor := vfs.anonBlockDevMinorNext + const maxDevMinor = (1 << 20) - 1 + for minor < maxDevMinor { + if _, ok := vfs.anonBlockDevMinor[minor]; !ok { + vfs.anonBlockDevMinor[minor] = struct{}{} + vfs.anonBlockDevMinorNext = minor + 1 + return minor, nil + } + minor++ + } + return 0, syserror.EMFILE +} + +// PutAnonBlockDevMinor deallocates a minor device number returned by a +// previous call to GetAnonBlockDevMinor. +func (vfs *VirtualFilesystem) PutAnonBlockDevMinor(minor uint32) { + vfs.anonBlockDevMinorMu.Lock() + defer vfs.anonBlockDevMinorMu.Unlock() + delete(vfs.anonBlockDevMinor, minor) + if minor < vfs.anonBlockDevMinorNext { + vfs.anonBlockDevMinorNext = minor + } +} diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go index 1f21b0b31..1f6f56293 100644 --- a/pkg/sentry/vfs/vfs.go +++ b/pkg/sentry/vfs/vfs.go @@ -80,6 +80,14 @@ type VirtualFilesystem struct { devicesMu sync.RWMutex devices map[devTuple]*registeredDevice + // anonBlockDevMinor contains all allocated anonymous block device minor + // numbers. anonBlockDevMinorNext is a lower bound for the smallest + // unallocated anonymous block device number. anonBlockDevMinorNext and + // anonBlockDevMinor are protected by anonBlockDevMinorMu. + anonBlockDevMinorMu sync.Mutex + anonBlockDevMinorNext uint32 + anonBlockDevMinor map[uint32]struct{} + // fsTypes contains all registered FilesystemTypes. fsTypes is protected by // fsTypesMu. fsTypesMu sync.RWMutex @@ -94,10 +102,12 @@ type VirtualFilesystem struct { // New returns a new VirtualFilesystem with no mounts or FilesystemTypes. 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{}), + mountpoints: make(map[*Dentry]map[*Mount]struct{}), + devices: make(map[devTuple]*registeredDevice), + anonBlockDevMinorNext: 1, + anonBlockDevMinor: make(map[uint32]struct{}), + fsTypes: make(map[string]*registeredFilesystemType), + filesystems: make(map[*Filesystem]struct{}), } vfs.mounts.Init() return vfs |