diff options
author | Dean Deng <deandeng@google.com> | 2020-06-23 18:31:53 -0700 |
---|---|---|
committer | gVisor bot <gvisor-bot@google.com> | 2020-06-23 18:33:04 -0700 |
commit | 65a587dedf1a30b3614a66532d2b448026b9c540 (patch) | |
tree | 425422cc8115fa4534dba7e270becfd2d4201723 /pkg/sentry/vfs | |
parent | acf519a77b480e8d974186568bd66eaa89bac024 (diff) |
Complete inotify IN_EXCL_UNLINK implementation in VFS2.
Events were only skipped on parent directories after their children were
unlinked; events on the unlinked file itself need to be skipped as well.
As a result, all Watches.Notify() calls need to know whether the dentry where
the call came from was unlinked.
Updates #1479.
PiperOrigin-RevId: 317979476
Diffstat (limited to 'pkg/sentry/vfs')
-rw-r--r-- | pkg/sentry/vfs/inotify.go | 39 |
1 files changed, 16 insertions, 23 deletions
diff --git a/pkg/sentry/vfs/inotify.go b/pkg/sentry/vfs/inotify.go index 36e7a3767..6043a0566 100644 --- a/pkg/sentry/vfs/inotify.go +++ b/pkg/sentry/vfs/inotify.go @@ -467,21 +467,16 @@ func (w *Watches) Remove(id uint64) { delete(w.ws, id) } -// Notify queues a new event with all watches in this set. -func (w *Watches) Notify(name string, events, cookie uint32, et EventType) { - w.NotifyWithExclusions(name, events, cookie, et, false) -} - -// NotifyWithExclusions queues a new event with watches in this set. Watches -// with IN_EXCL_UNLINK are skipped if the event is coming from a child that -// has been unlinked. -func (w *Watches) NotifyWithExclusions(name string, events, cookie uint32, et EventType, unlinked bool) { +// Notify queues a new event with watches in this set. Watches with +// IN_EXCL_UNLINK are skipped if the event is coming from a child that has been +// unlinked. +func (w *Watches) Notify(name string, events, cookie uint32, et EventType, unlinked bool) { // N.B. We don't defer the unlocks because Notify is in the hot path of // all IO operations, and the defer costs too much for small IO // operations. w.mu.RLock() for _, watch := range w.ws { - if unlinked && watch.ExcludeUnlinkedChildren() && et == PathEvent { + if unlinked && watch.ExcludeUnlinked() && et == PathEvent { continue } watch.Notify(name, events, cookie) @@ -492,7 +487,7 @@ func (w *Watches) NotifyWithExclusions(name string, events, cookie uint32, et Ev // HandleDeletion is called when the watch target is destroyed to emit // the appropriate events. func (w *Watches) HandleDeletion() { - w.Notify("", linux.IN_DELETE_SELF, 0, InodeEvent) + w.Notify("", linux.IN_DELETE_SELF, 0, InodeEvent, true /* unlinked */) // 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 @@ -539,14 +534,12 @@ func (w *Watch) OwnerID() uint64 { return w.owner.id } -// ExcludeUnlinkedChildren indicates whether the watched object should continue -// to be notified of events of its children after they have been unlinked, e.g. -// for an open file descriptor. +// ExcludeUnlinked indicates whether the watched object should continue to be +// notified of events originating from a path that has been unlinked. // -// TODO(gvisor.dev/issue/1479): Implement IN_EXCL_UNLINK. -// We can do this by keeping track of the set of unlinked children in Watches -// to skip notification. -func (w *Watch) ExcludeUnlinkedChildren() bool { +// For example, if "foo/bar" is opened and then unlinked, operations on the +// open fd may be ignored by watches on "foo" and "foo/bar" with IN_EXCL_UNLINK. +func (w *Watch) ExcludeUnlinked() bool { return atomic.LoadUint32(&w.mask)&linux.IN_EXCL_UNLINK != 0 } @@ -710,10 +703,10 @@ func InotifyEventFromStatMask(mask uint32) uint32 { // parent/child notifications, the child is notified first in this case. func InotifyRemoveChild(self, parent *Watches, name string) { if self != nil { - self.Notify("", linux.IN_ATTRIB, 0, InodeEvent) + self.Notify("", linux.IN_ATTRIB, 0, InodeEvent, true /* unlinked */) } if parent != nil { - parent.Notify(name, linux.IN_DELETE, 0, InodeEvent) + parent.Notify(name, linux.IN_DELETE, 0, InodeEvent, true /* unlinked */) } } @@ -726,13 +719,13 @@ func InotifyRename(ctx context.Context, renamed, oldParent, newParent *Watches, } cookie := uniqueid.InotifyCookie(ctx) if oldParent != nil { - oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent) + oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent, false /* unlinked */) } if newParent != nil { - newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent) + newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent, false /* unlinked */) } // Somewhat surprisingly, self move events do not have a cookie. if renamed != nil { - renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent) + renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent, false /* unlinked */) } } |