diff options
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/save_restore.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/special_file.go | 96 |
2 files changed, 100 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/gofer/save_restore.go b/pkg/sentry/fsimpl/gofer/save_restore.go index e67422a2f..8dcbc61ed 100644 --- a/pkg/sentry/fsimpl/gofer/save_restore.go +++ b/pkg/sentry/fsimpl/gofer/save_restore.go @@ -158,6 +158,10 @@ func (d *dentryPlatformFile) afterLoad() { // afterLoad is invoked by stateify. func (fd *specialFileFD) afterLoad() { fd.handle.fd = -1 + if fd.hostFileMapper.IsInited() { + // Ensure that we don't call fd.hostFileMapper.Init() again. + fd.hostFileMapperInitOnce.Do(func() {}) + } } // CompleteRestore implements diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go index 8e3c41808..a8d47b65b 100644 --- a/pkg/sentry/fsimpl/gofer/special_file.go +++ b/pkg/sentry/fsimpl/gofer/special_file.go @@ -22,9 +22,13 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/errors/linuxerr" "gvisor.dev/gvisor/pkg/fdnotifier" + "gvisor.dev/gvisor/pkg/hostarch" "gvisor.dev/gvisor/pkg/metric" "gvisor.dev/gvisor/pkg/p9" + "gvisor.dev/gvisor/pkg/safemem" + "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" "gvisor.dev/gvisor/pkg/sentry/fsmetric" + "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/usermem" @@ -74,6 +78,16 @@ type specialFileFD struct { bufMu sync.Mutex `state:"nosave"` haveBuf uint32 buf []byte + + // If handle.fd >= 0, hostFileMapper caches mappings of handle.fd, and + // hostFileMapperInitOnce is used to initialize it on first use. + hostFileMapperInitOnce sync.Once `state:"nosave"` + hostFileMapper fsutil.HostFileMapper + + // If handle.fd >= 0, fileRefs counts references on memmap.File offsets. + // fileRefs is protected by fileRefsMu. + fileRefsMu sync.Mutex `state:"nosave"` + fileRefs fsutil.FrameRefSet } func newSpecialFileFD(h handle, mnt *vfs.Mount, d *dentry, flags uint32) (*specialFileFD, error) { @@ -392,3 +406,85 @@ func (fd *specialFileFD) sync(ctx context.Context, forFilesystemSync bool) error } return nil } + +// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. +func (fd *specialFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error { + if fd.handle.fd < 0 || fd.filesystem().opts.forcePageCache { + return linuxerr.ENODEV + } + // After this point, fd may be used as a memmap.Mappable and memmap.File. + fd.hostFileMapperInitOnce.Do(fd.hostFileMapper.Init) + return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts) +} + +// AddMapping implements memmap.Mappable.AddMapping. +func (fd *specialFileFD) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar hostarch.AddrRange, offset uint64, writable bool) error { + fd.hostFileMapper.IncRefOn(memmap.MappableRange{offset, offset + uint64(ar.Length())}) + return nil +} + +// RemoveMapping implements memmap.Mappable.RemoveMapping. +func (fd *specialFileFD) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar hostarch.AddrRange, offset uint64, writable bool) { + fd.hostFileMapper.DecRefOn(memmap.MappableRange{offset, offset + uint64(ar.Length())}) +} + +// CopyMapping implements memmap.Mappable.CopyMapping. +func (fd *specialFileFD) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR hostarch.AddrRange, offset uint64, writable bool) error { + return fd.AddMapping(ctx, ms, dstAR, offset, writable) +} + +// Translate implements memmap.Mappable.Translate. +func (fd *specialFileFD) Translate(ctx context.Context, required, optional memmap.MappableRange, at hostarch.AccessType) ([]memmap.Translation, error) { + mr := optional + if fd.filesystem().opts.limitHostFDTranslation { + mr = maxFillRange(required, optional) + } + return []memmap.Translation{ + { + Source: mr, + File: fd, + Offset: mr.Start, + Perms: hostarch.AnyAccess, + }, + }, nil +} + +// InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable. +func (fd *specialFileFD) InvalidateUnsavable(ctx context.Context) error { + return nil +} + +// IncRef implements memmap.File.IncRef. +func (fd *specialFileFD) IncRef(fr memmap.FileRange) { + fd.fileRefsMu.Lock() + defer fd.fileRefsMu.Unlock() + fd.fileRefs.IncRefAndAccount(fr) +} + +// DecRef implements memmap.File.DecRef. +func (fd *specialFileFD) DecRef(fr memmap.FileRange) { + fd.fileRefsMu.Lock() + defer fd.fileRefsMu.Unlock() + fd.fileRefs.DecRefAndAccount(fr) +} + +// MapInternal implements memmap.File.MapInternal. +func (fd *specialFileFD) MapInternal(fr memmap.FileRange, at hostarch.AccessType) (safemem.BlockSeq, error) { + fd.requireHostFD() + return fd.hostFileMapper.MapInternal(fr, int(fd.handle.fd), at.Write) +} + +// FD implements memmap.File.FD. +func (fd *specialFileFD) FD() int { + fd.requireHostFD() + return int(fd.handle.fd) +} + +func (fd *specialFileFD) requireHostFD() { + if fd.handle.fd < 0 { + // This is possible if fd was successfully mmapped before saving, then + // was restored without a host FD. This is unrecoverable: without a + // host FD, we can't mmap this file post-restore. + panic("gofer.specialFileFD can no longer be memory-mapped without a host FD") + } +} |