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

1 files changed, 15 insertions, 12 deletions

diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go
index 242eb5ecb..cb92b6eee 100644
--- a/pkg/sentry/vfs/dentry.go
+++ b/pkg/sentry/vfs/dentry.go
@@ -196,11 +196,12 @@ func (d *Dentry) OnZeroWatches(ctx context.Context) {
 // PrepareDeleteDentry must be called before attempting to delete the file
 // represented by d. If PrepareDeleteDentry succeeds, the caller must call
 // AbortDeleteDentry or CommitDeleteDentry depending on the deletion's outcome.
+// +checklocksacquire:d.mu
 func (vfs *VirtualFilesystem) PrepareDeleteDentry(mntns *MountNamespace, d *Dentry) error {
 	vfs.mountMu.Lock()
 	if mntns.mountpoints[d] != 0 {
 		vfs.mountMu.Unlock()
-		return linuxerr.EBUSY
+		return linuxerr.EBUSY // +checklocksforce: inconsistent return.
 	}
 	d.mu.Lock()
 	vfs.mountMu.Unlock()
@@ -211,14 +212,14 @@ func (vfs *VirtualFilesystem) PrepareDeleteDentry(mntns *MountNamespace, d *Dent
 
 // AbortDeleteDentry must be called after PrepareDeleteDentry if the deletion
 // fails.
-// +checklocks:d.mu
+// +checklocksrelease:d.mu
 func (vfs *VirtualFilesystem) AbortDeleteDentry(d *Dentry) {
 	d.mu.Unlock()
 }
 
 // CommitDeleteDentry must be called after PrepareDeleteDentry if the deletion
 // succeeds.
-// +checklocks:d.mu
+// +checklocksrelease:d.mu
 func (vfs *VirtualFilesystem) CommitDeleteDentry(ctx context.Context, d *Dentry) {
 	d.dead = true
 	d.mu.Unlock()
@@ -249,16 +250,18 @@ func (vfs *VirtualFilesystem) InvalidateDentry(ctx context.Context, d *Dentry) {
 // Preconditions:
 // * If to is not nil, it must be a child Dentry from the same Filesystem.
 // * from != to.
+// +checklocksacquire:from.mu
+// +checklocksacquire:to.mu
 func (vfs *VirtualFilesystem) PrepareRenameDentry(mntns *MountNamespace, from, to *Dentry) error {
 	vfs.mountMu.Lock()
 	if mntns.mountpoints[from] != 0 {
 		vfs.mountMu.Unlock()
-		return linuxerr.EBUSY
+		return linuxerr.EBUSY // +checklocksforce: no locks acquired.
 	}
 	if to != nil {
 		if mntns.mountpoints[to] != 0 {
 			vfs.mountMu.Unlock()
-			return linuxerr.EBUSY
+			return linuxerr.EBUSY // +checklocksforce: no locks acquired.
 		}
 		to.mu.Lock()
 	}
@@ -267,13 +270,13 @@ func (vfs *VirtualFilesystem) PrepareRenameDentry(mntns *MountNamespace, from, t
 	// Return with from.mu and to.mu locked, which will be unlocked by
 	// AbortRenameDentry, CommitRenameReplaceDentry, or
 	// CommitRenameExchangeDentry.
-	return nil
+	return nil // +checklocksforce: to may not be acquired.
 }
 
 // AbortRenameDentry must be called after PrepareRenameDentry if the rename
 // fails.
-// +checklocks:from.mu
-// +checklocks:to.mu
+// +checklocksrelease:from.mu
+// +checklocksrelease:to.mu
 func (vfs *VirtualFilesystem) AbortRenameDentry(from, to *Dentry) {
 	from.mu.Unlock()
 	if to != nil {
@@ -286,8 +289,8 @@ func (vfs *VirtualFilesystem) AbortRenameDentry(from, to *Dentry) {
 // that was replaced by from.
 //
 // Preconditions: PrepareRenameDentry was previously called on from and to.
-// +checklocks:from.mu
-// +checklocks:to.mu
+// +checklocksrelease:from.mu
+// +checklocksrelease:to.mu
 func (vfs *VirtualFilesystem) CommitRenameReplaceDentry(ctx context.Context, from, to *Dentry) {
 	from.mu.Unlock()
 	if to != nil {
@@ -303,8 +306,8 @@ func (vfs *VirtualFilesystem) CommitRenameReplaceDentry(ctx context.Context, fro
 // from and to are exchanged by rename(RENAME_EXCHANGE).
 //
 // Preconditions: PrepareRenameDentry was previously called on from and to.
-// +checklocks:from.mu
-// +checklocks:to.mu
+// +checklocksrelease:from.mu
+// +checklocksrelease:to.mu
 func (vfs *VirtualFilesystem) CommitRenameExchangeDentry(from, to *Dentry) {
 	from.mu.Unlock()
 	to.mu.Unlock()