diff options
-rw-r--r-- | pkg/sentry/fsimpl/ext/dentry.go | 11 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/gofer/directory.go | 1 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/gofer/filesystem.go | 59 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 73 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/kernfs/kernfs.go | 7 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/overlay/overlay.go | 5 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/tmpfs/directory.go | 4 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/tmpfs/filesystem.go | 12 | ||||
-rw-r--r-- | pkg/sentry/fsimpl/tmpfs/tmpfs.go | 19 | ||||
-rw-r--r-- | pkg/sentry/syscalls/linux/vfs2/inotify.go | 7 | ||||
-rw-r--r-- | pkg/sentry/vfs/anonfs.go | 7 | ||||
-rw-r--r-- | pkg/sentry/vfs/dentry.go | 32 | ||||
-rw-r--r-- | pkg/sentry/vfs/inotify.go | 108 | ||||
-rw-r--r-- | pkg/sentry/vfs/vfs.go | 3 | ||||
-rw-r--r-- | test/syscalls/linux/BUILD | 1 | ||||
-rw-r--r-- | test/syscalls/linux/inotify.cc | 251 |
16 files changed, 523 insertions, 77 deletions
diff --git a/pkg/sentry/fsimpl/ext/dentry.go b/pkg/sentry/fsimpl/ext/dentry.go index 6bd1a9fc6..55902322a 100644 --- a/pkg/sentry/fsimpl/ext/dentry.go +++ b/pkg/sentry/fsimpl/ext/dentry.go @@ -63,12 +63,17 @@ func (d *dentry) DecRef() { // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. // -// TODO(gvisor.dev/issue/1479): Implement inotify. -func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {} +// TODO(b/134676337): Implement inotify. +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {} // Watches implements vfs.DentryImpl.Watches. // -// TODO(gvisor.dev/issue/1479): Implement inotify. +// TODO(b/134676337): Implement inotify. func (d *dentry) Watches() *vfs.Watches { return nil } + +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +// +// TODO(b/134676337): Implement inotify. +func (d *dentry) OnZeroWatches() {} diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go index 480510b2a..5d83fe363 100644 --- a/pkg/sentry/fsimpl/gofer/directory.go +++ b/pkg/sentry/fsimpl/gofer/directory.go @@ -138,6 +138,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba fd.dirents = ds } + d.InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent) if d.cachedMetadataAuthoritative() { d.touchAtime(fd.vfsfd.Mount()) } diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index f065c4bad..0321fd384 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -371,6 +371,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir } parent.touchCMtime() parent.dirents = nil + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent) return nil } if fs.opts.interop == InteropModeShared { @@ -400,6 +405,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir } parent.touchCMtime() parent.dirents = nil + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent) return nil } @@ -530,6 +540,18 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b return err } } + + // Generate inotify events for rmdir or unlink. + if dir { + parent.watches.Notify(name, linux.IN_DELETE|linux.IN_ISDIR, 0, vfs.InodeEvent) + } else { + var cw *vfs.Watches + if child != nil { + cw = &child.watches + } + vfs.InotifyRemoveChild(cw, &parent.watches, name) + } + if child != nil { vfsObj.CommitDeleteDentry(&child.vfsd) child.setDeleted() @@ -1018,6 +1040,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } childVFSFD = &fd.vfsfd } + d.watches.Notify(name, linux.IN_CREATE, 0, vfs.PathEvent) return childVFSFD, nil } @@ -1203,6 +1226,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa newParent.incLinks() } } + vfs.InotifyRename(ctx, &renamed.watches, &oldParent.watches, &newParent.watches, oldName, newName, renamed.isDir()) return nil } @@ -1215,12 +1239,21 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + if err := d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()) + fs.renameMuRUnlockAndCheckCaching(&ds) + + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + d.InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // StatAt implements vfs.FilesystemImpl.StatAt. @@ -1344,24 +1377,38 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.setxattr(ctx, rp.Credentials(), &opts) + if err := d.setxattr(ctx, rp.Credentials(), &opts); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(&ds) + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt. func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + if err := d.removexattr(ctx, rp.Credentials(), name); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.removexattr(ctx, rp.Credentials(), name) + fs.renameMuRUnlockAndCheckCaching(&ds) + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // PrependPath implements vfs.FilesystemImpl.PrependPath. diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index 43c8153a4..c6c284ff3 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -665,6 +665,9 @@ type dentry struct { pipe *pipe.VFSPipe locks vfs.FileLocks + + // Inotify watches for this dentry. + watches vfs.Watches } // dentryAttrMask returns a p9.AttrMask enabling all attributes used by the @@ -947,6 +950,8 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin } else { atomic.StoreInt64(&d.atime, dentryTimestampFromStatx(stat.Atime)) } + // Restore mask bits that we cleared earlier. + stat.Mask |= linux.STATX_ATIME } if setLocalMtime { if stat.Mtime.Nsec == linux.UTIME_NOW { @@ -954,6 +959,8 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin } else { atomic.StoreInt64(&d.mtime, dentryTimestampFromStatx(stat.Mtime)) } + // Restore mask bits that we cleared earlier. + stat.Mask |= linux.STATX_MTIME } atomic.StoreInt64(&d.ctime, now) if stat.Mask&linux.STATX_SIZE != 0 { @@ -1051,15 +1058,34 @@ func (d *dentry) decRefLocked() { } // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. -// -// TODO(gvisor.dev/issue/1479): Implement inotify. -func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {} +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) { + if d.isDir() { + events |= linux.IN_ISDIR + } + + d.fs.renameMu.RLock() + // The ordering below is important, Linux always notifies the parent first. + if d.parent != nil { + d.parent.watches.NotifyWithExclusions(d.name, events, cookie, et, d.isDeleted()) + } + d.watches.Notify("", events, cookie, et) + d.fs.renameMu.RUnlock() +} // Watches implements vfs.DentryImpl.Watches. -// -// TODO(gvisor.dev/issue/1479): Implement inotify. func (d *dentry) Watches() *vfs.Watches { - return nil + return &d.watches +} + +// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches. +// +// If no watches are left on this dentry and it has no references, cache it. +func (d *dentry) OnZeroWatches() { + if atomic.LoadInt64(&d.refs) == 0 { + d.fs.renameMu.Lock() + d.checkCachingLocked() + d.fs.renameMu.Unlock() + } } // checkCachingLocked should be called after d's reference count becomes 0 or it @@ -1093,6 +1119,9 @@ func (d *dentry) checkCachingLocked() { // Deleted and invalidated dentries with zero references are no longer // reachable by path resolution and should be dropped immediately. if d.vfsd.IsDead() { + if d.isDeleted() { + d.watches.HandleDeletion() + } if d.cached { d.fs.cachedDentries.Remove(d) d.fs.cachedDentriesLen-- @@ -1101,6 +1130,14 @@ func (d *dentry) checkCachingLocked() { d.destroyLocked() return } + // If d still has inotify watches and it is not deleted or invalidated, we + // cannot cache it and allow it to be evicted. Otherwise, we will lose its + // watches, even if a new dentry is created for the same file in the future. + // Note that the size of d.watches cannot concurrently transition from zero + // to non-zero, because adding a watch requires holding a reference on d. + if d.watches.Size() > 0 { + return + } // If d is already cached, just move it to the front of the LRU. if d.cached { d.fs.cachedDentries.Remove(d) @@ -1277,7 +1314,7 @@ func (d *dentry) userXattrSupported() bool { return filetype == linux.S_IFREG || filetype == linux.S_IFDIR } -// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDirectory(). +// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDir(). func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool) error { // O_TRUNC unconditionally requires us to obtain a new handle (opened with // O_TRUNC). @@ -1422,7 +1459,13 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu // SetStat implements vfs.FileDescriptionImpl.SetStat. func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { - return fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()) + if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()); err != nil { + return err + } + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + fd.dentry().InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // Listxattr implements vfs.FileDescriptionImpl.Listxattr. @@ -1437,12 +1480,22 @@ func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOption // Setxattr implements vfs.FileDescriptionImpl.Setxattr. func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error { - return fd.dentry().setxattr(ctx, auth.CredentialsFromContext(ctx), &opts) + d := fd.dentry() + if err := d.setxattr(ctx, auth.CredentialsFromContext(ctx), &opts); err != nil { + return err + } + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // Removexattr implements vfs.FileDescriptionImpl.Removexattr. func (fd *fileDescription) Removexattr(ctx context.Context, name string) error { - return fd.dentry().removexattr(ctx, auth.CredentialsFromContext(ctx), name) + d := fd.dentry() + if err := d.removexattr(ctx, auth.CredentialsFromContext(ctx), name); err != nil { + return err + } + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // LockBSD implements vfs.FileDescriptionImpl.LockBSD. diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go index 07a9dc830..55349f2a3 100644 --- a/pkg/sentry/fsimpl/kernfs/kernfs.go +++ b/pkg/sentry/fsimpl/kernfs/kernfs.go @@ -228,7 +228,7 @@ func (d *Dentry) destroy() { // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. // // TODO(gvisor.dev/issue/1479): Implement inotify. -func (d *Dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {} +func (d *Dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {} // Watches implements vfs.DentryImpl.Watches. // @@ -237,6 +237,11 @@ func (d *Dentry) Watches() *vfs.Watches { return nil } +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +// +// TODO(gvisor.dev/issue/1479): Implement inotify. +func (d *Dentry) OnZeroWatches() {} + // InsertChild inserts child into the vfs dentry cache with the given name under // this dentry. This does not update the directory inode, so calling this on // its own isn't sufficient to insert a child into a directory. InsertChild diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go index e11a3ff19..e720d4825 100644 --- a/pkg/sentry/fsimpl/overlay/overlay.go +++ b/pkg/sentry/fsimpl/overlay/overlay.go @@ -528,6 +528,11 @@ func (d *dentry) Watches() *vfs.Watches { return nil } +// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches. +// +// TODO(gvisor.dev/issue/1479): Implement inotify. +func (d *dentry) OnZeroWatches() {} + // iterLayers invokes yield on each layer comprising d, from top to bottom. If // any call to yield returns false, iterLayer stops iteration. func (d *dentry) iterLayers(yield func(vd vfs.VirtualDentry, isUpper bool) bool) { diff --git a/pkg/sentry/fsimpl/tmpfs/directory.go b/pkg/sentry/fsimpl/tmpfs/directory.go index 913b8a6c5..b172abc15 100644 --- a/pkg/sentry/fsimpl/tmpfs/directory.go +++ b/pkg/sentry/fsimpl/tmpfs/directory.go @@ -79,7 +79,6 @@ func (dir *directory) removeChildLocked(child *dentry) { dir.iterMu.Lock() dir.childList.Remove(child) dir.iterMu.Unlock() - child.unlinked = true } type directoryFD struct { @@ -107,13 +106,14 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba fs := fd.filesystem() dir := fd.inode().impl.(*directory) + defer fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent) + // fs.mu is required to read d.parent and dentry.name. fs.mu.RLock() defer fs.mu.RUnlock() dir.iterMu.Lock() defer dir.iterMu.Unlock() - fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent) fd.inode().touchAtime(fd.vfsfd.Mount()) if fd.off == 0 { diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go index 637d84e04..85d8e37b2 100644 --- a/pkg/sentry/fsimpl/tmpfs/filesystem.go +++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go @@ -638,14 +638,16 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error // SetStatAt implements vfs.FilesystemImpl.SetStatAt. func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() return err } if err := d.inode.setStat(ctx, rp.Credentials(), &opts.Stat); err != nil { + fs.mu.RUnlock() return err } + fs.mu.RUnlock() if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { d.InotifyWithParent(ev, 0, vfs.InodeEvent) @@ -788,14 +790,16 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt // SetxattrAt implements vfs.FilesystemImpl.SetxattrAt. func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() return err } if err := d.inode.setxattr(rp.Credentials(), &opts); err != nil { + fs.mu.RUnlock() return err } + fs.mu.RUnlock() d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) return nil @@ -804,14 +808,16 @@ func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt // RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt. func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() return err } if err := d.inode.removexattr(rp.Credentials(), name); err != nil { + fs.mu.RUnlock() return err } + fs.mu.RUnlock() d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) return nil diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go index a94333ee0..a85bfc968 100644 --- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go +++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go @@ -215,11 +215,6 @@ type dentry struct { // filesystem.mu. name string - // unlinked indicates whether this dentry has been unlinked from its parent. - // It is only set to true on an unlink operation, and never set from true to - // false. unlinked is protected by filesystem.mu. - unlinked bool - // dentryEntry (ugh) links dentries into their parent directory.childList. dentryEntry @@ -259,18 +254,20 @@ func (d *dentry) DecRef() { } // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. -func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) { +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) { if d.inode.isDir() { events |= linux.IN_ISDIR } + d.inode.fs.mu.RLock() // The ordering below is important, Linux always notifies the parent first. if d.parent != nil { - // Note that d.parent or d.name may be stale if there is a concurrent - // rename operation. Inotify does not provide consistency guarantees. - d.parent.inode.watches.NotifyWithExclusions(d.name, events, cookie, et, d.unlinked) + // tmpfs never calls VFS.InvalidateDentry(), so d.vfsd.IsDead() indicates + // that d was deleted. + d.parent.inode.watches.NotifyWithExclusions(d.name, events, cookie, et, d.vfsd.IsDead()) } d.inode.watches.Notify("", events, cookie, et) + d.inode.fs.mu.RUnlock() } // Watches implements vfs.DentryImpl.Watches. @@ -278,6 +275,9 @@ func (d *dentry) Watches() *vfs.Watches { return &d.inode.watches } +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +func (d *dentry) OnZeroWatches() {} + // inode represents a filesystem object. type inode struct { // fs is the owning filesystem. fs is immutable. @@ -336,7 +336,6 @@ func (i *inode) init(impl interface{}, fs *filesystem, kuid auth.KUID, kgid auth i.ctime = now i.mtime = now // i.nlink initialized by caller - i.watches = vfs.Watches{} i.impl = impl } diff --git a/pkg/sentry/syscalls/linux/vfs2/inotify.go b/pkg/sentry/syscalls/linux/vfs2/inotify.go index 7d50b6a16..74e5287b7 100644 --- a/pkg/sentry/syscalls/linux/vfs2/inotify.go +++ b/pkg/sentry/syscalls/linux/vfs2/inotify.go @@ -116,8 +116,11 @@ func InotifyAddWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kern } defer d.DecRef() - fd = ino.AddWatch(d.Dentry(), mask) - return uintptr(fd), nil, err + fd, err = ino.AddWatch(d.Dentry(), mask) + if err != nil { + return 0, nil, err + } + return uintptr(fd), nil, nil } // InotifyRmWatch implements the inotify_rm_watch() syscall. diff --git a/pkg/sentry/vfs/anonfs.go b/pkg/sentry/vfs/anonfs.go index b7c6b60b8..746af03ec 100644 --- a/pkg/sentry/vfs/anonfs.go +++ b/pkg/sentry/vfs/anonfs.go @@ -301,7 +301,7 @@ func (d *anonDentry) DecRef() { // InotifyWithParent implements DentryImpl.InotifyWithParent. // // TODO(gvisor.dev/issue/1479): Implement inotify. -func (d *anonDentry) InotifyWithParent(events uint32, cookie uint32, et EventType) {} +func (d *anonDentry) InotifyWithParent(events, cookie uint32, et EventType) {} // Watches implements DentryImpl.Watches. // @@ -309,3 +309,8 @@ func (d *anonDentry) InotifyWithParent(events uint32, cookie uint32, et EventTyp func (d *anonDentry) Watches() *Watches { return nil } + +// OnZeroWatches implements Dentry.OnZeroWatches. +// +// TODO(gvisor.dev/issue/1479): Implement inotify. +func (d *anonDentry) OnZeroWatches() {} diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go index 24af13eb1..cea3e6955 100644 --- a/pkg/sentry/vfs/dentry.go +++ b/pkg/sentry/vfs/dentry.go @@ -113,12 +113,29 @@ type DentryImpl interface { // // Note that the events may not actually propagate up to the user, depending // on the event masks. - InotifyWithParent(events uint32, cookie uint32, et EventType) + InotifyWithParent(events, cookie uint32, et EventType) // Watches returns the set of inotify watches for the file corresponding to // the Dentry. Dentries that are hard links to the same underlying file // share the same watches. + // + // Watches may return nil if the dentry belongs to a FilesystemImpl that + // does not support inotify. If an implementation returns a non-nil watch + // set, it must always return a non-nil watch set. Likewise, if an + // implementation returns a nil watch set, it must always return a nil watch + // set. + // + // The caller does not need to hold a reference on the dentry. Watches() *Watches + + // OnZeroWatches is called whenever the number of watches on a dentry drops + // to zero. This is needed by some FilesystemImpls (e.g. gofer) to manage + // dentry lifetime. + // + // The caller does not need to hold a reference on the dentry. OnZeroWatches + // may acquire inotify locks, so to prevent deadlock, no inotify locks should + // be held by the caller. + OnZeroWatches() } // IncRef increments d's reference count. @@ -149,17 +166,26 @@ func (d *Dentry) isMounted() bool { return atomic.LoadUint32(&d.mounts) != 0 } -// InotifyWithParent notifies all watches on the inodes for this dentry and +// InotifyWithParent notifies all watches on the targets represented by d and // its parent of events. -func (d *Dentry) InotifyWithParent(events uint32, cookie uint32, et EventType) { +func (d *Dentry) InotifyWithParent(events, cookie uint32, et EventType) { d.impl.InotifyWithParent(events, cookie, et) } // Watches returns the set of inotify watches associated with d. +// +// Watches will return nil if d belongs to a FilesystemImpl that does not +// support inotify. func (d *Dentry) Watches() *Watches { return d.impl.Watches() } +// OnZeroWatches performs cleanup tasks whenever the number of watches on a +// dentry drops to zero. +func (d *Dentry) OnZeroWatches() { + d.impl.OnZeroWatches() +} + // The following functions are exported so that filesystem implementations can // use them. The vfs package, and users of VFS, should not call these // functions. diff --git a/pkg/sentry/vfs/inotify.go b/pkg/sentry/vfs/inotify.go index 7fa7d2d0c..36e7a3767 100644 --- a/pkg/sentry/vfs/inotify.go +++ b/pkg/sentry/vfs/inotify.go @@ -49,9 +49,6 @@ const ( // Inotify represents an inotify instance created by inotify_init(2) or // inotify_init1(2). Inotify implements FileDescriptionImpl. // -// Lock ordering: -// Inotify.mu -> Watches.mu -> Inotify.evMu -// // +stateify savable type Inotify struct { vfsfd FileDescription @@ -122,17 +119,31 @@ func NewInotifyFD(ctx context.Context, vfsObj *VirtualFilesystem, flags uint32) // Release implements FileDescriptionImpl.Release. Release removes all // watches and frees all resources for an inotify instance. func (i *Inotify) Release() { + var ds []*Dentry // We need to hold i.mu to avoid a race with concurrent calls to // Inotify.handleDeletion from Watches. There's no risk of Watches // accessing this Inotify after the destructor ends, because we remove all // references to it below. i.mu.Lock() - defer i.mu.Unlock() for _, w := range i.watches { // Remove references to the watch from the watches set on the target. We // don't need to worry about the references from i.watches, since this // file description is about to be destroyed. - w.set.Remove(i.id) + d := w.target + ws := d.Watches() + // Watchable dentries should never return a nil watch set. + if ws == nil { + panic("Cannot remove watch from an unwatchable dentry") + } + ws.Remove(i.id) + if ws.Size() == 0 { + ds = append(ds, d) + } + } + i.mu.Unlock() + + for _, d := range ds { + d.OnZeroWatches() } } @@ -272,20 +283,19 @@ func (i *Inotify) queueEvent(ev *Event) { // newWatchLocked creates and adds a new watch to target. // -// Precondition: i.mu must be locked. -func (i *Inotify) newWatchLocked(target *Dentry, mask uint32) *Watch { - targetWatches := target.Watches() +// Precondition: i.mu must be locked. ws must be the watch set for target d. +func (i *Inotify) newWatchLocked(d *Dentry, ws *Watches, mask uint32) *Watch { w := &Watch{ - owner: i, - wd: i.nextWatchIDLocked(), - set: targetWatches, - mask: mask, + owner: i, + wd: i.nextWatchIDLocked(), + target: d, + mask: mask, } // Hold the watch in this inotify instance as well as the watch set on the // target. i.watches[w.wd] = w - targetWatches.Add(w) + ws.Add(w) return w } @@ -312,7 +322,9 @@ func (i *Inotify) handleDeletion(w *Watch) { // AddWatch constructs a new inotify watch and adds it to the target. It // returns the watch descriptor returned by inotify_add_watch(2). -func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 { +// +// The caller must hold a reference on target. +func (i *Inotify) AddWatch(target *Dentry, mask uint32) (int32, error) { // Note: Locking this inotify instance protects the result returned by // Lookup() below. With the lock held, we know for sure the lookup result // won't become stale because it's impossible for *this* instance to @@ -320,8 +332,14 @@ func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 { i.mu.Lock() defer i.mu.Unlock() + ws := target.Watches() + if ws == nil { + // While Linux supports inotify watches on all filesystem types, watches on + // filesystems like kernfs are not generally useful, so we do not. + return 0, syserror.EPERM + } // Does the target already have a watch from this inotify instance? - if existing := target.Watches().Lookup(i.id); existing != nil { + if existing := ws.Lookup(i.id); existing != nil { newmask := mask if mask&linux.IN_MASK_ADD != 0 { // "Add (OR) events to watch mask for this pathname if it already @@ -329,12 +347,12 @@ func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 { newmask |= atomic.LoadUint32(&existing.mask) } atomic.StoreUint32(&existing.mask, newmask) - return existing.wd + return existing.wd, nil } // No existing watch, create a new watch. - w := i.newWatchLocked(target, mask) - return w.wd + w := i.newWatchLocked(target, ws, mask) + return w.wd, nil } // RmWatch looks up an inotify watch for the given 'wd' and configures the @@ -353,9 +371,19 @@ func (i *Inotify) RmWatch(wd int32) error { delete(i.watches, wd) // Remove the watch from the watch target. - w.set.Remove(w.OwnerID()) + ws := w.target.Watches() + // AddWatch ensures that w.target has a non-nil watch set. + if ws == nil { + panic("Watched dentry cannot have nil watch set") + } + ws.Remove(w.OwnerID()) + remaining := ws.Size() i.mu.Unlock() + if remaining == 0 { + w.target.OnZeroWatches() + } + // Generate the event for the removal. i.queueEvent(newEvent(wd, "", linux.IN_IGNORED, 0)) @@ -374,6 +402,13 @@ type Watches struct { ws map[uint64]*Watch } +// Size returns the number of watches held by w. +func (w *Watches) Size() int { + w.mu.Lock() + defer w.mu.Unlock() + return len(w.ws) +} + // Lookup returns the watch owned by an inotify instance with the given id. // Returns nil if no such watch exists. // @@ -459,10 +494,6 @@ func (w *Watches) NotifyWithExclusions(name string, events, cookie uint32, et Ev func (w *Watches) HandleDeletion() { w.Notify("", linux.IN_DELETE_SELF, 0, InodeEvent) - // TODO(gvisor.dev/issue/1479): This doesn't work because maps are not copied - // by value. Ideally, we wouldn't have this circular locking so we can just - // notify of IN_DELETE_SELF in the same loop below. - // // We can't hold w.mu while calling watch.handleDeletion to preserve lock // ordering w.r.t to the owner inotify instances. Instead, atomically move // the watches map into a local variable so we can iterate over it safely. @@ -495,9 +526,8 @@ type Watch struct { // Descriptor for this watch. This is unique across an inotify instance. wd int32 - // set is the watch set containing this watch. It belongs to the target file - // of this watch. - set *Watches + // target is a dentry representing the watch target. Its watch set contains this watch. + target *Dentry // Events being monitored via this watch. Must be accessed with atomic // memory operations. @@ -606,7 +636,7 @@ func (e *Event) setName(name string) { func (e *Event) sizeOf() int { s := inotifyEventBaseSize + int(e.len) if s < inotifyEventBaseSize { - panic("overflow") + panic("Overflowed event size") } return s } @@ -676,11 +706,15 @@ func InotifyEventFromStatMask(mask uint32) uint32 { } // InotifyRemoveChild sends the appriopriate notifications to the watch sets of -// the child being removed and its parent. +// the child being removed and its parent. Note that unlike most pairs of +// parent/child notifications, the child is notified first in this case. func InotifyRemoveChild(self, parent *Watches, name string) { - self.Notify("", linux.IN_ATTRIB, 0, InodeEvent) - parent.Notify(name, linux.IN_DELETE, 0, InodeEvent) - // TODO(gvisor.dev/issue/1479): implement IN_EXCL_UNLINK. + if self != nil { + self.Notify("", linux.IN_ATTRIB, 0, InodeEvent) + } + if parent != nil { + parent.Notify(name, linux.IN_DELETE, 0, InodeEvent) + } } // InotifyRename sends the appriopriate notifications to the watch sets of the @@ -691,8 +725,14 @@ func InotifyRename(ctx context.Context, renamed, oldParent, newParent *Watches, dirEv = linux.IN_ISDIR } cookie := uniqueid.InotifyCookie(ctx) - oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent) - newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent) + if oldParent != nil { + oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent) + } + if newParent != nil { + newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent) + } // Somewhat surprisingly, self move events do not have a cookie. - renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent) + if renamed != nil { + renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent) + } } diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go index 9acca8bc7..58c7ad778 100644 --- a/pkg/sentry/vfs/vfs.go +++ b/pkg/sentry/vfs/vfs.go @@ -24,6 +24,9 @@ // Locks acquired by FilesystemImpls between Prepare{Delete,Rename}Dentry and Commit{Delete,Rename*}Dentry // VirtualFilesystem.filesystemsMu // EpollInstance.mu +// Inotify.mu +// Watches.mu +// Inotify.evMu // VirtualFilesystem.fsTypesMu // // Locking Dentry.mu in multiple Dentries requires holding diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD index 078e4a284..7282d675e 100644 --- a/test/syscalls/linux/BUILD +++ b/test/syscalls/linux/BUILD @@ -974,6 +974,7 @@ cc_binary( "//test/util:thread_util", "@com_google_absl//absl/strings", "@com_google_absl//absl/strings:str_format", + "@com_google_absl//absl/synchronization", "@com_google_absl//absl/time", ], ) diff --git a/test/syscalls/linux/inotify.cc b/test/syscalls/linux/inotify.cc index 1d1a7171d..13e096e9c 100644 --- a/test/syscalls/linux/inotify.cc +++ b/test/syscalls/linux/inotify.cc @@ -29,6 +29,7 @@ #include "absl/strings/str_cat.h" #include "absl/strings/str_format.h" #include "absl/strings/str_join.h" +#include "absl/synchronization/mutex.h" #include "absl/time/clock.h" #include "absl/time/time.h" #include "test/util/epoll_util.h" @@ -1305,7 +1306,7 @@ TEST(Inotify, UtimesGeneratesAttribEvent) { const int wd = ASSERT_NO_ERRNO_AND_VALUE( InotifyAddWatch(fd.get(), root.path(), IN_ALL_EVENTS)); - struct timeval times[2] = {{1, 0}, {2, 0}}; + const struct timeval times[2] = {{1, 0}, {2, 0}}; EXPECT_THAT(futimes(file1_fd.get(), times), SyscallSucceeds()); const std::vector<Event> events = @@ -2018,7 +2019,7 @@ TEST(Inotify, ExcludeUnlinkInodeEvents_NoRandomSave) { Event(IN_MODIFY, wd, Basename(file.path())), })); - struct timeval times[2] = {{1, 0}, {2, 0}}; + const struct timeval times[2] = {{1, 0}, {2, 0}}; ASSERT_THAT(futimes(fd.get(), times), SyscallSucceeds()); events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get())); EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd, Basename(file.path()))})); @@ -2030,6 +2031,252 @@ TEST(Inotify, ExcludeUnlinkInodeEvents_NoRandomSave) { EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd, Basename(file.path()))})); } +// This test helps verify that the lock order of filesystem and inotify locks +// is respected when inotify instances and watch targets are concurrently being +// destroyed. +TEST(InotifyTest, InotifyAndTargetDestructionDoNotDeadlock_NoRandomSave) { + const DisableSave ds; // Too many syscalls. + + // A file descriptor protected by a mutex. This ensures that while a + // descriptor is in use, it cannot be closed and reused for a different file + // description. + struct atomic_fd { + int fd; + absl::Mutex mu; + }; + + // Set up initial inotify instances. + constexpr int num_fds = 3; + std::vector<atomic_fd> fds(num_fds); + for (int i = 0; i < num_fds; i++) { + int fd; + ASSERT_THAT(fd = inotify_init1(IN_NONBLOCK), SyscallSucceeds()); + fds[i].fd = fd; + } + + // Set up initial watch targets. + std::vector<std::string> paths; + for (int i = 0; i < 3; i++) { + paths.push_back(NewTempAbsPath()); + ASSERT_THAT(mknod(paths[i].c_str(), S_IFREG | 0600, 0), SyscallSucceeds()); + } + + constexpr absl::Duration runtime = absl::Seconds(4); + + // Constantly replace each inotify instance with a new one. + auto replace_fds = [&] { + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + for (auto& afd : fds) { + int new_fd; + ASSERT_THAT(new_fd = inotify_init1(IN_NONBLOCK), SyscallSucceeds()); + absl::MutexLock l(&afd.mu); + ASSERT_THAT(close(afd.fd), SyscallSucceeds()); + afd.fd = new_fd; + for (auto& p : paths) { + // inotify_add_watch may fail if the file at p was deleted. + ASSERT_THAT(inotify_add_watch(afd.fd, p.c_str(), IN_ALL_EVENTS), + AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT))); + } + } + sched_yield(); + } + }; + + std::list<ScopedThread> ts; + for (int i = 0; i < 3; i++) { + ts.emplace_back(replace_fds); + } + + // Constantly replace each watch target with a new one. + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + for (auto& p : paths) { + ASSERT_THAT(unlink(p.c_str()), SyscallSucceeds()); + ASSERT_THAT(mknod(p.c_str(), S_IFREG | 0600, 0), SyscallSucceeds()); + } + sched_yield(); + } +} + +// This test helps verify that the lock order of filesystem and inotify locks +// is respected when adding/removing watches occurs concurrently with the +// removal of their targets. +TEST(InotifyTest, AddRemoveUnlinkDoNotDeadlock_NoRandomSave) { + const DisableSave ds; // Too many syscalls. + + // Set up inotify instances. + constexpr int num_fds = 3; + std::vector<int> fds(num_fds); + for (int i = 0; i < num_fds; i++) { + ASSERT_THAT(fds[i] = inotify_init1(IN_NONBLOCK), SyscallSucceeds()); + } + + // Set up initial watch targets. + std::vector<std::string> paths; + for (int i = 0; i < 3; i++) { + paths.push_back(NewTempAbsPath()); + ASSERT_THAT(mknod(paths[i].c_str(), S_IFREG | 0600, 0), SyscallSucceeds()); + } + + constexpr absl::Duration runtime = absl::Seconds(1); + + // Constantly add/remove watches for each inotify instance/watch target pair. + auto add_remove_watches = [&] { + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + for (int fd : fds) { + for (auto& p : paths) { + // Do not assert on inotify_add_watch and inotify_rm_watch. They may + // fail if the file at p was deleted. inotify_add_watch may also fail + // if another thread beat us to adding a watch. + const int wd = inotify_add_watch(fd, p.c_str(), IN_ALL_EVENTS); + if (wd > 0) { + inotify_rm_watch(fd, wd); + } + } + } + sched_yield(); + } + }; + + std::list<ScopedThread> ts; + for (int i = 0; i < 15; i++) { + ts.emplace_back(add_remove_watches); + } + + // Constantly replace each watch target with a new one. + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + for (auto& p : paths) { + ASSERT_THAT(unlink(p.c_str()), SyscallSucceeds()); + ASSERT_THAT(mknod(p.c_str(), S_IFREG | 0600, 0), SyscallSucceeds()); + } + sched_yield(); + } +} + +// This test helps verify that the lock order of filesystem and inotify locks +// is respected when many inotify events and filesystem operations occur +// simultaneously. +TEST(InotifyTest, NotifyNoDeadlock_NoRandomSave) { + const DisableSave ds; // Too many syscalls. + + const TempPath parent = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); + const std::string dir = parent.path(); + + // mu protects file, which will change on rename. + absl::Mutex mu; + std::string file = NewTempAbsPathInDir(dir); + ASSERT_THAT(mknod(file.c_str(), 0644 | S_IFREG, 0), SyscallSucceeds()); + + const absl::Duration runtime = absl::Milliseconds(300); + + // Add/remove watches on dir and file. + ScopedThread add_remove_watches([&] { + const FileDescriptor ifd = + ASSERT_NO_ERRNO_AND_VALUE(InotifyInit1(IN_NONBLOCK)); + int dir_wd = ASSERT_NO_ERRNO_AND_VALUE( + InotifyAddWatch(ifd.get(), dir, IN_ALL_EVENTS)); + int file_wd; + { + absl::ReaderMutexLock l(&mu); + file_wd = ASSERT_NO_ERRNO_AND_VALUE( + InotifyAddWatch(ifd.get(), file, IN_ALL_EVENTS)); + } + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + ASSERT_THAT(inotify_rm_watch(ifd.get(), file_wd), SyscallSucceeds()); + ASSERT_THAT(inotify_rm_watch(ifd.get(), dir_wd), SyscallSucceeds()); + dir_wd = ASSERT_NO_ERRNO_AND_VALUE( + InotifyAddWatch(ifd.get(), dir, IN_ALL_EVENTS)); + { + absl::ReaderMutexLock l(&mu); + file_wd = ASSERT_NO_ERRNO_AND_VALUE( + InotifyAddWatch(ifd.get(), file, IN_ALL_EVENTS)); + } + sched_yield(); + } + }); + + // Modify attributes on dir and file. + ScopedThread stats([&] { + int fd, dir_fd; + { + absl::ReaderMutexLock l(&mu); + ASSERT_THAT(fd = open(file.c_str(), O_RDONLY), SyscallSucceeds()); + } + ASSERT_THAT(dir_fd = open(dir.c_str(), O_RDONLY | O_DIRECTORY), + SyscallSucceeds()); + const struct timeval times[2] = {{1, 0}, {2, 0}}; + + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + { + absl::ReaderMutexLock l(&mu); + EXPECT_THAT(utimes(file.c_str(), times), SyscallSucceeds()); + } + EXPECT_THAT(futimes(fd, times), SyscallSucceeds()); + EXPECT_THAT(utimes(dir.c_str(), times), SyscallSucceeds()); + EXPECT_THAT(futimes(dir_fd, times), SyscallSucceeds()); + sched_yield(); + } + }); + + // Modify extended attributes on dir and file. + ScopedThread xattrs([&] { + // TODO(gvisor.dev/issue/1636): Support extended attributes in runsc gofer. + if (!IsRunningOnGvisor()) { + int fd; + { + absl::ReaderMutexLock l(&mu); + ASSERT_THAT(fd = open(file.c_str(), O_RDONLY), SyscallSucceeds()); + } + + const char* name = "user.test"; + int val = 123; + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + { + absl::ReaderMutexLock l(&mu); + ASSERT_THAT( + setxattr(file.c_str(), name, &val, sizeof(val), /*flags=*/0), + SyscallSucceeds()); + ASSERT_THAT(removexattr(file.c_str(), name), SyscallSucceeds()); + } + + ASSERT_THAT(fsetxattr(fd, name, &val, sizeof(val), /*flags=*/0), + SyscallSucceeds()); + ASSERT_THAT(fremovexattr(fd, name), SyscallSucceeds()); + sched_yield(); + } + } + }); + + // Read and write file's contents. Read and write dir's entries. + ScopedThread read_write([&] { + int fd; + { + absl::ReaderMutexLock l(&mu); + ASSERT_THAT(fd = open(file.c_str(), O_RDWR), SyscallSucceeds()); + } + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + int val = 123; + ASSERT_THAT(write(fd, &val, sizeof(val)), SyscallSucceeds()); + ASSERT_THAT(read(fd, &val, sizeof(val)), SyscallSucceeds()); + TempPath new_file = + ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileIn(dir)); + ASSERT_NO_ERRNO(ListDir(dir, false)); + new_file.reset(); + sched_yield(); + } + }); + + // Rename file. + for (auto start = absl::Now(); absl::Now() - start < runtime;) { + const std::string new_path = NewTempAbsPathInDir(dir); + { + absl::WriterMutexLock l(&mu); + ASSERT_THAT(rename(file.c_str(), new_path.c_str()), SyscallSucceeds()); + file = new_path; + } + sched_yield(); + } +} + } // namespace } // namespace testing } // namespace gvisor |