From 16b751b6c610ec2c5a913cb8a818e9239ee7da71 Mon Sep 17 00:00:00 2001 From: Adin Scannell Date: Thu, 1 Jul 2021 15:05:28 -0700 Subject: Mix checklocks and atomic analyzers. This change makes the checklocks analyzer considerable more powerful, adding: * The ability to traverse complex structures, e.g. to have multiple nested fields as part of the annotation. * The ability to resolve simple anonymous functions and closures, and perform lock analysis across these invocations. This does not apply to closures that are passed elsewhere, since it is not possible to know the context in which they might be invoked. * The ability to annotate return values in addition to receivers and other parameters, with the same complex structures noted above. * Ignoring locking semantics for "fresh" objects, i.e. objects that are allocated in the local frame (typically a new-style function). * Sanity checking of locking state across block transitions and returns, to ensure that no unexpected locks are held. Note that initially, most of these findings are excluded by a comprehensive nogo.yaml. The findings that are included are fundamental lock violations. The changes here should be relatively low risk, minor refactorings to either include necessary annotations to simplify the code structure (in general removing closures in favor of methods) so that the analyzer can be easily track the lock state. This change additional includes two changes to nogo itself: * Sanity checking of all types to ensure that the binary and ast-derived types have a consistent objectpath, to prevent the bug above from occurring silently (and causing much confusion). This also requires a trick in order to ensure that serialized facts are consumable downstream. This can be removed with https://go-review.googlesource.com/c/tools/+/331789 merged. * A minor refactoring to isolation the objdump settings in its own package. This was originally used to implement the sanity check above, but this information is now being passed another way. The minor refactor is preserved however, since it cleans up the code slightly and is minimal risk. PiperOrigin-RevId: 382613300 --- pkg/sentry/fsimpl/gofer/filesystem.go | 16 +++++++++------- pkg/sentry/fsimpl/gofer/gofer.go | 18 ++++++++++++------ pkg/sentry/fsimpl/gofer/revalidate.go | 10 ++++++---- pkg/sentry/fsimpl/gofer/symlink.go | 2 +- pkg/sentry/fsimpl/kernfs/filesystem.go | 4 ++-- pkg/sentry/fsimpl/overlay/filesystem.go | 4 ++-- pkg/sentry/fsimpl/verity/filesystem.go | 2 ++ 7 files changed, 34 insertions(+), 22 deletions(-) (limited to 'pkg/sentry/fsimpl') diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index 237d17921..652e5fe77 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -147,6 +147,7 @@ func putDentrySlice(ds *[]*dentry) { // but dentry slices are allocated lazily, and it's much easier to say "defer // fs.renameMuRUnlockAndCheckCaching(&ds)" than "defer func() { // fs.renameMuRUnlockAndCheckCaching(ds) }()" to work around this. +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuRUnlockAndCheckCaching(ctx context.Context, dsp **[]*dentry) { fs.renameMu.RUnlock() if *dsp == nil { @@ -159,6 +160,7 @@ func (fs *filesystem) renameMuRUnlockAndCheckCaching(ctx context.Context, dsp ** putDentrySlice(*dsp) } +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuUnlockAndCheckCaching(ctx context.Context, ds **[]*dentry) { if *ds == nil { fs.renameMu.Unlock() @@ -540,7 +542,7 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b if child.syntheticChildren != 0 { // This is definitely not an empty directory, irrespective of // fs.opts.interop. - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: PrepareDeleteDentry called if child != nil. return linuxerr.ENOTEMPTY } // If InteropModeShared is in effect and the first call to @@ -550,12 +552,12 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b // still exist) would be a waste of time. if child.cachedMetadataAuthoritative() { if !child.isDir() { - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above. return syserror.ENOTDIR } for _, grandchild := range child.children { if grandchild != nil { - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above. return linuxerr.ENOTEMPTY } } @@ -565,12 +567,12 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b } else { // child must be a non-directory file. if child != nil && child.isDir() { - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above. return syserror.EISDIR } if rp.MustBeDir() { if child != nil { - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above. } return syserror.ENOTDIR } @@ -583,7 +585,7 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b err = parent.file.unlinkAt(ctx, name, flags) if err != nil { if child != nil { - vfsObj.AbortDeleteDentry(&child.vfsd) + vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above. } return err } @@ -601,7 +603,7 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b } if child != nil { - vfsObj.CommitDeleteDentry(ctx, &child.vfsd) + vfsObj.CommitDeleteDentry(ctx, &child.vfsd) // +checklocksforce: see above. child.setDeleted() if child.isSynthetic() { parent.syntheticChildren-- diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index fe4c2e0e1..2f85215d9 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -947,10 +947,10 @@ func (d *dentry) cachedMetadataAuthoritative() bool { // updateFromP9Attrs is called to update d's metadata after an update from the // remote filesystem. // Precondition: d.metadataMu must be locked. +// +checklocks:d.metadataMu func (d *dentry) updateFromP9AttrsLocked(mask p9.AttrMask, attr *p9.Attr) { if mask.Mode { if got, want := uint32(attr.Mode.FileType()), d.fileType(); got != want { - d.metadataMu.Unlock() panic(fmt.Sprintf("gofer.dentry file type changed from %#o to %#o", want, got)) } atomic.StoreUint32(&d.mode, uint32(attr.Mode)) @@ -989,6 +989,7 @@ func (d *dentry) updateFromP9AttrsLocked(mask p9.AttrMask, attr *p9.Attr) { // Preconditions: !d.isSynthetic(). // Preconditions: d.metadataMu is locked. +// +checklocks:d.metadataMu func (d *dentry) refreshSizeLocked(ctx context.Context) error { d.handleMu.RLock() @@ -1020,6 +1021,7 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error { // Preconditions: // * !d.isSynthetic(). // * d.metadataMu is locked. +// +checklocks:d.metadataMu func (d *dentry) updateFromGetattrLocked(ctx context.Context) error { // Use d.readFile or d.writeFile, which represent 9P FIDs that have been // opened, in preference to d.file, which represents a 9P fid that has not. @@ -1044,7 +1046,8 @@ func (d *dentry) updateFromGetattrLocked(ctx context.Context) error { _, attrMask, attr, err := file.getAttr(ctx, dentryAttrMask()) if handleMuRLocked { - d.handleMu.RUnlock() // must be released before updateFromP9AttrsLocked() + // handleMu must be released before updateFromP9AttrsLocked(). + d.handleMu.RUnlock() // +checklocksforce: complex case. } if err != nil { return err @@ -1470,7 +1473,7 @@ func (d *dentry) checkCachingLocked(ctx context.Context, renameMuWriteLocked boo if d.isDeleted() { d.watches.HandleDeletion(ctx) } - d.destroyLocked(ctx) + d.destroyLocked(ctx) // +checklocksforce: renameMu must be acquired at this point. return } // If d still has inotify watches and it is not deleted or invalidated, it @@ -1498,7 +1501,7 @@ func (d *dentry) checkCachingLocked(ctx context.Context, renameMuWriteLocked boo delete(d.parent.children, d.name) d.parent.dirMu.Unlock() } - d.destroyLocked(ctx) + d.destroyLocked(ctx) // +checklocksforce: see above. return } @@ -1527,7 +1530,7 @@ func (d *dentry) checkCachingLocked(ctx context.Context, renameMuWriteLocked boo d.fs.renameMu.Lock() defer d.fs.renameMu.Unlock() } - d.fs.evictCachedDentryLocked(ctx) + d.fs.evictCachedDentryLocked(ctx) // +checklocksforce: see above. } } @@ -1544,6 +1547,7 @@ func (d *dentry) removeFromCacheLocked() { // Precondition: fs.renameMu must be locked for writing; it may be temporarily // unlocked. +// +checklocks:fs.renameMu func (fs *filesystem) evictAllCachedDentriesLocked(ctx context.Context) { for fs.cachedDentriesLen != 0 { fs.evictCachedDentryLocked(ctx) @@ -1552,6 +1556,7 @@ func (fs *filesystem) evictAllCachedDentriesLocked(ctx context.Context) { // Preconditions: // * fs.renameMu must be locked for writing; it may be temporarily unlocked. +// +checklocks:fs.renameMu func (fs *filesystem) evictCachedDentryLocked(ctx context.Context) { fs.cacheMu.Lock() victim := fs.cachedDentries.Back() @@ -1588,7 +1593,7 @@ func (fs *filesystem) evictCachedDentryLocked(ctx context.Context) { // will try to acquire fs.renameMu (which we have already acquired). Hence, // fs.renameMu will synchronize the destroy attempts. victim.cachingMu.Unlock() - victim.destroyLocked(ctx) + victim.destroyLocked(ctx) // +checklocksforce: owned as precondition, victim.fs == fs. } // destroyLocked destroys the dentry. @@ -1598,6 +1603,7 @@ func (fs *filesystem) evictCachedDentryLocked(ctx context.Context) { // * d.refs == 0. // * d.parent.children[d.name] != d, i.e. d is not reachable by path traversal // from its former parent dentry. +// +checklocks:d.fs.renameMu func (d *dentry) destroyLocked(ctx context.Context) { switch atomic.LoadInt64(&d.refs) { case 0: diff --git a/pkg/sentry/fsimpl/gofer/revalidate.go b/pkg/sentry/fsimpl/gofer/revalidate.go index 8f81f0822..226790a11 100644 --- a/pkg/sentry/fsimpl/gofer/revalidate.go +++ b/pkg/sentry/fsimpl/gofer/revalidate.go @@ -247,16 +247,16 @@ func (fs *filesystem) revalidateHelper(ctx context.Context, vfsObj *vfs.VirtualF if found && !d.isSynthetic() { // First dentry is where the search is starting, just update attributes // since it cannot be replaced. - d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr) + d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr) // +checklocksforce: acquired by lockAllMetadata. } - d.metadataMu.Unlock() + d.metadataMu.Unlock() // +checklocksforce: see above. continue } // Note that synthetic dentries will always fails the comparison check // below. if !found || d.qidPath != stats[i].QID.Path { - d.metadataMu.Unlock() + d.metadataMu.Unlock() // +checklocksforce: see above. if !found && d.isSynthetic() { // We have a synthetic file, and no remote file has arisen to replace // it. @@ -298,7 +298,7 @@ func (fs *filesystem) revalidateHelper(ctx context.Context, vfsObj *vfs.VirtualF } // The file at this path hasn't changed. Just update cached metadata. - d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr) + d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr) // +checklocksforce: see above. d.metadataMu.Unlock() } @@ -354,6 +354,7 @@ func (r *revalidateState) add(name string, d *dentry) { r.dentries = append(r.dentries, d) } +// +checklocksignore func (r *revalidateState) lockAllMetadata() { for _, d := range r.dentries { d.metadataMu.Lock() @@ -372,6 +373,7 @@ func (r *revalidateState) popFront() *dentry { // reset releases all metadata locks and resets all fields to allow this // instance to be reused. +// +checklocksignore func (r *revalidateState) reset() { if r.locked { // Unlock any remaining dentries. diff --git a/pkg/sentry/fsimpl/gofer/symlink.go b/pkg/sentry/fsimpl/gofer/symlink.go index 2ec819f86..dbd834c67 100644 --- a/pkg/sentry/fsimpl/gofer/symlink.go +++ b/pkg/sentry/fsimpl/gofer/symlink.go @@ -41,7 +41,7 @@ func (d *dentry) readlink(ctx context.Context, mnt *vfs.Mount) (string, error) { d.haveTarget = true d.target = target } - d.dataMu.Unlock() + d.dataMu.Unlock() // +checklocksforce: guaranteed locked from above. } return target, err } diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go index 38c2b6df1..20d2526ad 100644 --- a/pkg/sentry/fsimpl/kernfs/filesystem.go +++ b/pkg/sentry/fsimpl/kernfs/filesystem.go @@ -752,7 +752,7 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa fs.deferDecRef(replaced) replaceVFSD = replaced.VFSDentry() } - virtfs.CommitRenameReplaceDentry(ctx, srcVFSD, replaceVFSD) + virtfs.CommitRenameReplaceDentry(ctx, srcVFSD, replaceVFSD) // +checklocksforce: to may be nil, that's okay. return nil } @@ -788,7 +788,7 @@ func (fs *Filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error defer mntns.DecRef(ctx) vfsd := d.VFSDentry() if err := virtfs.PrepareDeleteDentry(mntns, vfsd); err != nil { - return err + return err // +checklocksforce: vfsd is not locked. } if err := parentDentry.inode.RmDir(ctx, d.name, d.inode); err != nil { diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go index 41207211a..77f9affc1 100644 --- a/pkg/sentry/fsimpl/overlay/filesystem.go +++ b/pkg/sentry/fsimpl/overlay/filesystem.go @@ -87,7 +87,7 @@ func putDentrySlice(ds *[]*dentry) { // fs.renameMuRUnlockAndCheckDrop(&ds)" than "defer func() { // fs.renameMuRUnlockAndCheckDrop(ds) }()" to work around this. // -// +checklocks:fs.renameMu +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuRUnlockAndCheckDrop(ctx context.Context, dsp **[]*dentry) { fs.renameMu.RUnlock() if *dsp == nil { @@ -113,7 +113,7 @@ func (fs *filesystem) renameMuRUnlockAndCheckDrop(ctx context.Context, dsp **[]* putDentrySlice(*dsp) } -// +checklocks:fs.renameMu +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuUnlockAndCheckDrop(ctx context.Context, ds **[]*dentry) { if *ds == nil { fs.renameMu.Unlock() diff --git a/pkg/sentry/fsimpl/verity/filesystem.go b/pkg/sentry/fsimpl/verity/filesystem.go index e4bfbd3c9..358a66072 100644 --- a/pkg/sentry/fsimpl/verity/filesystem.go +++ b/pkg/sentry/fsimpl/verity/filesystem.go @@ -75,6 +75,7 @@ func putDentrySlice(ds *[]*dentry) { // but dentry slices are allocated lazily, and it's much easier to say "defer // fs.renameMuRUnlockAndCheckDrop(&ds)" than "defer func() { // fs.renameMuRUnlockAndCheckDrop(ds) }()" to work around this. +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuRUnlockAndCheckDrop(ctx context.Context, ds **[]*dentry) { fs.renameMu.RUnlock() if *ds == nil { @@ -90,6 +91,7 @@ func (fs *filesystem) renameMuRUnlockAndCheckDrop(ctx context.Context, ds **[]*d putDentrySlice(*ds) } +// +checklocksrelease:fs.renameMu func (fs *filesystem) renameMuUnlockAndCheckDrop(ctx context.Context, ds **[]*dentry) { if *ds == nil { fs.renameMu.Unlock() -- cgit v1.2.3