mm: implement prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME)

PiperOrigin-RevId: 696324755

pkg/abi/linux/prctl.go

@@ -149,6 +149,12 @@ const (
 	PR_SCHED_CORE_SCOPE_THREAD       = 0
 	PR_SCHED_CORE_SCOPE_THREAD_GROUP = 1
 
+	// PR_SET_VMA sets VMA names.
+	PR_SET_VMA           = 0x53564d41
+	PR_SET_VMA_ANON_NAME = 0
+	// From kernel/sys.c:
+	ANON_VMA_NAME_MAX_LEN = 80
+
 	// PR_SET_PTRACER allows a specific process (or any, if PR_SET_PTRACER_ANY is
 	// specified) to ptrace the current task.
 	PR_SET_PTRACER     = 0x59616d61

pkg/sentry/fsimpl/erofs/BUILD

@@ -14,6 +14,7 @@ go_template_instance(
     template = "//pkg/sentry/vfs/genericfstree:generic_fstree",
     types = {
         "Dentry": "dentry",
+        "Filesystem": "filesystem",
     },
 )
 
@@ -70,6 +71,7 @@ go_library(
         "//pkg/sentry/memmap",
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/vfs",
+        "//pkg/sync",
         "//pkg/usermem",
     ],
 )

pkg/sentry/fsimpl/erofs/erofs.go

@@ -19,7 +19,6 @@ import (
 	"os"
 	"runtime"
 	"strconv"
-	"sync"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
@@ -30,6 +29,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 // Name is the filesystem name. It is part of the interface used by users,
@@ -72,6 +72,9 @@ type filesystem struct {
 	// reduce the lock contention. Bucket is chosen based on the hash calculation
 	// on nid in filesystem.inodeBucket.
 	inodeBuckets []inodeBucket
+
+	// ancestryMu is required by genericfstree.
+	ancestryMu sync.RWMutex `state:"nosave"`
 }
 
 // InternalFilesystemOptions may be passed as

pkg/sentry/fsimpl/erofs/filesystem.go

@@ -430,15 +430,15 @@ func (fs *filesystem) RemoveXattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 
 // PrependPath implements vfs.FilesystemImpl.PrependPath.
 func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
-	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
+	return genericPrependPath(fs, vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
+}
+
+// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
+func (fs *filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
+	return genericIsDescendant(fs, vfsroot.Dentry(), vd.Dentry().Impl().(*dentry))
 }
 
 // MountOptions implements vfs.FilesystemImpl.MountOptions.
 func (fs *filesystem) MountOptions() string {
 	return fs.mopts
 }
-
-// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
-func (fs *filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
-	return genericIsDescendant(vfsroot.Dentry(), vd.Dentry().Impl().(*dentry))
-}

pkg/sentry/fsimpl/gofer/BUILD

@@ -49,6 +49,7 @@ go_template_instance(
     template = "//pkg/sentry/vfs/genericfstree:generic_fstree",
     types = {
         "Dentry": "dentry",
+        "Filesystem": "filesystem",
     },
 )
 

pkg/sentry/fsimpl/gofer/dentry_impl.go

@@ -538,14 +538,14 @@ func (d *dentry) restoreFile(ctx context.Context, opts *vfs.CompleteRestoreOptio
 		inode, err := controlFD.Walk(ctx, d.name)
 		if err != nil {
 			if !dt.isDir() || !dt.forMountpoint {
-				return fmt.Errorf("failed to walk %q of type %x: %w", genericDebugPathname(d), dt.fileType(), err)
+				return fmt.Errorf("failed to walk %q of type %x: %w", genericDebugPathname(d.fs, d), dt.fileType(), err)
 			}
 
 			// Recreate directories that were created during volume mounting, since
 			// during restore we don't attempt to remount them.
 			inode, err = controlFD.MkdirAt(ctx, d.name, linux.FileMode(d.mode.Load()), lisafs.UID(d.uid.Load()), lisafs.GID(d.gid.Load()))
 			if err != nil {
-				return fmt.Errorf("failed to create mountpoint directory at %q: %w", genericDebugPathname(d), err)
+				return fmt.Errorf("failed to create mountpoint directory at %q: %w", genericDebugPathname(d.fs, d), err)
 			}
 		}
 		return dt.restoreFile(ctx, &inode, opts)
@@ -558,21 +558,21 @@ func (d *dentry) restoreFile(ctx context.Context, opts *vfs.CompleteRestoreOptio
 		})
 		if err != nil {
 			if !dt.isDir() || !dt.forMountpoint {
-				return fmt.Errorf("failed to walk %q of type %x: %w", genericDebugPathname(d), dt.fileType(), err)
+				return fmt.Errorf("failed to walk %q of type %x: %w", genericDebugPathname(d.fs, d), dt.fileType(), err)
 			}
 
 			// Recreate directories that were created during volume mounting, since
 			// during restore we don't attempt to remount them.
 			if err := unix.Mkdirat(controlFD, d.name, d.mode.Load()); err != nil {
-				return fmt.Errorf("failed to create mountpoint directory at %q: %w", genericDebugPathname(d), err)
+				return fmt.Errorf("failed to create mountpoint directory at %q: %w", genericDebugPathname(d.fs, d), err)
 			}
 
 			// Try again...
 			childFD, err = tryOpen(func(flags int) (int, error) {
 				return unix.Openat(controlFD, d.name, flags, 0)
 			})
 			if err != nil {
-				return fmt.Errorf("failed to open %q: %w", genericDebugPathname(d), err)
+				return fmt.Errorf("failed to open %q: %w", genericDebugPathname(d.fs, d), err)
 			}
 		}
 		return dt.restoreFile(ctx, childFD, opts)

pkg/sentry/fsimpl/gofer/directfs_dentry.go

@@ -452,7 +452,7 @@ func (d *directfsDentry) getCreatedChild(name string, uid, gid int, isDir bool)
 	deleteChild := func() {
 		// Best effort attempt to remove the newly created child on failure.
 		if err := unix.Unlinkat(d.controlFD, name, unlinkFlags); err != nil {
-			log.Warningf("error unlinking newly created child %q after failure: %v", filepath.Join(genericDebugPathname(&d.dentry), name), err)
+			log.Warningf("error unlinking newly created child %q after failure: %v", filepath.Join(genericDebugPathname(d.fs, &d.dentry), name), err)
 		}
 	}
 
@@ -518,7 +518,7 @@ func (d *directfsDentry) bindAt(ctx context.Context, name string, creds *auth.Cr
 	hbep := opts.Endpoint.(transport.HostBoundEndpoint)
 	if err := hbep.SetBoundSocketFD(ctx, boundSocketFD); err != nil {
 		if err := unix.Unlinkat(d.controlFD, name, 0); err != nil {
-			log.Warningf("error unlinking newly created socket %q after failure: %v", filepath.Join(genericDebugPathname(&d.dentry), name), err)
+			log.Warningf("error unlinking newly created socket %q after failure: %v", filepath.Join(genericDebugPathname(d.fs, &d.dentry), name), err)
 		}
 		return nil, err
 	}
@@ -593,7 +593,7 @@ func (d *directfsDentry) getDirentsLocked(recordDirent func(name string, key ino
 		// TODO(gvisor.dev/issue/6665): Get rid of per-dirent stat.
 		stat, err := fsutil.StatAt(d.controlFD, name)
 		if err != nil {
-			log.Warningf("Getdent64: skipping file %q with failed stat, err: %v", path.Join(genericDebugPathname(&d.dentry), name), err)
+			log.Warningf("Getdent64: skipping file %q with failed stat, err: %v", path.Join(genericDebugPathname(d.fs, &d.dentry), name), err)
 			return
 		}
 		recordDirent(name, inoKeyFromStat(&stat), ftype)
@@ -650,7 +650,7 @@ func (d *directfsDentry) restoreFile(ctx context.Context, controlFD int, opts *v
 	var stat unix.Stat_t
 	if err := unix.Fstat(controlFD, &stat); err != nil {
 		_ = unix.Close(controlFD)
-		return fmt.Errorf("failed to stat %q: %w", genericDebugPathname(&d.dentry), err)
+		return fmt.Errorf("failed to stat %q: %w", genericDebugPathname(d.fs, &d.dentry), err)
 	}
 
 	d.controlFD = controlFD
@@ -672,12 +672,12 @@ func (d *directfsDentry) restoreFile(ctx context.Context, controlFD int, opts *v
 	if d.isRegularFile() {
 		if opts.ValidateFileSizes {
 			if d.size.RacyLoad() != uint64(stat.Size) {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: size changed from %d to %d", genericDebugPathname(&d.dentry), d.size.Load(), stat.Size)}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: size changed from %d to %d", genericDebugPathname(d.fs, &d.dentry), d.size.Load(), stat.Size)}
 			}
 		}
 		if opts.ValidateFileModificationTimestamps {
 			if want := dentryTimestampFromUnix(stat.Mtim); d.mtime.RacyLoad() != want {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime changed from %+v to %+v", genericDebugPathname(&d.dentry), linux.NsecToStatxTimestamp(d.mtime.RacyLoad()), linux.NsecToStatxTimestamp(want))}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime changed from %+v to %+v", genericDebugPathname(d.fs, &d.dentry), linux.NsecToStatxTimestamp(d.mtime.RacyLoad()), linux.NsecToStatxTimestamp(want))}
 			}
 		}
 	}
@@ -687,7 +687,7 @@ func (d *directfsDentry) restoreFile(ctx context.Context, controlFD int, opts *v
 
 	if rw, ok := d.fs.savedDentryRW[&d.dentry]; ok {
 		if err := d.ensureSharedHandle(ctx, rw.read, rw.write, false /* trunc */); err != nil {
-			return fmt.Errorf("failed to restore file handles (read=%t, write=%t) for %q: %w", rw.read, rw.write, genericDebugPathname(&d.dentry), err)
+			return fmt.Errorf("failed to restore file handles (read=%t, write=%t) for %q: %w", rw.read, rw.write, genericDebugPathname(d.fs, &d.dentry), err)
 		}
 	}
 

pkg/sentry/fsimpl/gofer/directory.go

@@ -51,8 +51,7 @@ func (d *dentry) isDir() bool {
 // +checklocks:d.childrenMu
 func (d *dentry) cacheNewChildLocked(child *dentry, name string) {
 	d.IncRef() // reference held by child on its parent
-	child.parent.Store(d)
-	child.name = name
+	genericSetParentAndName(d.fs, child, d, name)
 	if d.children == nil {
 		d.children = make(map[string]*dentry)
 	} else if c, ok := d.children[name]; ok {

pkg/sentry/fsimpl/gofer/filesystem.go

@@ -1418,7 +1418,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		return err
 	}
 	if renamed.isDir() {
-		if renamed == newParent || genericIsAncestorDentry(renamed, newParent) {
+		if renamed == newParent || genericIsAncestorDentry(fs, renamed, newParent) {
 			return linuxerr.EINVAL
 		}
 		if oldParent != newParent {
@@ -1456,7 +1456,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 			if !renamed.isDir() {
 				return linuxerr.EISDIR
 			}
-			if genericIsAncestorDentry(replaced, renamed) {
+			if genericIsAncestorDentry(fs, replaced, renamed) {
 				return linuxerr.ENOTEMPTY
 			}
 		} else {
@@ -1738,9 +1738,12 @@ func (fs *filesystem) RemoveXattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 
 // PrependPath implements vfs.FilesystemImpl.PrependPath.
 func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
-	fs.renameMu.RLock()
-	defer fs.renameMu.RUnlock()
-	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
+	return genericPrependPath(fs, vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
+}
+
+// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
+func (fs *filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
+	return genericIsDescendant(fs, vfsroot.Dentry(), vd.Dentry().Impl().(*dentry))
 }
 
 type mopt struct {
@@ -1804,8 +1807,3 @@ func (fs *filesystem) MountOptions() string {
 	}
 	return strings.Join(opts, ",")
 }
-
-// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
-func (fs *filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
-	return genericIsDescendant(vfsroot.Dentry(), vd.Dentry().Impl().(*dentry))
-}

pkg/sentry/fsimpl/gofer/gofer.go

@@ -25,11 +25,12 @@
 //	        dentry.childrenMu
 //	        filesystem.syncMu
 //	        dentry.metadataMu
-//	          *** "memmap.Mappable locks" below this point
+//	          *** "memmap.Mappable/MappingIdentity locks" below this point
 //	          dentry.mapsMu
 //	            *** "memmap.Mappable locks taken by Translate" below this point
 //	            dentry.handleMu
 //	              dentry.dataMu
+//	          filesystem.ancestryMu
 //	          filesystem.inoMu
 //	specialFileFD.mu
 //	  specialFileFD.bufMu
@@ -218,6 +219,10 @@ type filesystem struct {
 	//		it is reachable from its parent).
 	renameMu sync.RWMutex `state:"nosave"`
 
+	// ancestryMu additionally protects dentry.parent and dentry.name as
+	// required by genericfstree.
+	ancestryMu sync.RWMutex `state:"nosave"`
+
 	dentryCache *dentryCache
 
 	// syncableDentries contains all non-synthetic dentries. specialFileFDs

pkg/sentry/fsimpl/gofer/lisafs_dentry.go

@@ -547,18 +547,18 @@ func (d *lisafsDentry) restoreFile(ctx context.Context, inode *lisafs.Inode, opt
 	if d.isRegularFile() {
 		if opts.ValidateFileSizes {
 			if inode.Stat.Mask&linux.STATX_SIZE == 0 {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: file size not available", genericDebugPathname(&d.dentry))}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: file size not available", genericDebugPathname(d.fs, &d.dentry))}
 			}
 			if d.size.RacyLoad() != inode.Stat.Size {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: size changed from %d to %d", genericDebugPathname(&d.dentry), d.size.Load(), inode.Stat.Size)}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: file size validation failed: size changed from %d to %d", genericDebugPathname(d.fs, &d.dentry), d.size.Load(), inode.Stat.Size)}
 			}
 		}
 		if opts.ValidateFileModificationTimestamps {
 			if inode.Stat.Mask&linux.STATX_MTIME == 0 {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime not available", genericDebugPathname(&d.dentry))}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime not available", genericDebugPathname(d.fs, &d.dentry))}
 			}
 			if want := dentryTimestamp(inode.Stat.Mtime); d.mtime.RacyLoad() != want {
-				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime changed from %+v to %+v", genericDebugPathname(&d.dentry), linux.NsecToStatxTimestamp(d.mtime.RacyLoad()), linux.NsecToStatxTimestamp(want))}
+				return vfs.ErrCorruption{fmt.Errorf("gofer.dentry(%q).restoreFile: mtime validation failed: mtime changed from %+v to %+v", genericDebugPathname(d.fs, &d.dentry), linux.NsecToStatxTimestamp(d.mtime.RacyLoad()), linux.NsecToStatxTimestamp(want))}
 			}
 		}
 	}
@@ -568,7 +568,7 @@ func (d *lisafsDentry) restoreFile(ctx context.Context, inode *lisafs.Inode, opt
 
 	if rw, ok := d.fs.savedDentryRW[&d.dentry]; ok {
 		if err := d.ensureSharedHandle(ctx, rw.read, rw.write, false /* trunc */); err != nil {
-			return fmt.Errorf("failed to restore file handles (read=%t, write=%t) for %q: %w", rw.read, rw.write, genericDebugPathname(&d.dentry), err)
+			return fmt.Errorf("failed to restore file handles (read=%t, write=%t) for %q: %w", rw.read, rw.write, genericDebugPathname(d.fs, &d.dentry), err)
 		}
 	}
 

pkg/sentry/fsimpl/gofer/save_restore.go

@@ -130,7 +130,7 @@ func (d *dentry) prepareSaveRecursive(ctx context.Context) error {
 // beforeSave is invoked by stateify.
 func (d *dentry) beforeSave() {
 	if d.vfsd.IsDead() {
-		panic(fmt.Sprintf("gofer.dentry(%q).beforeSave: deleted and invalidated dentries can't be restored", genericDebugPathname(d)))
+		panic(fmt.Sprintf("gofer.dentry(%q).beforeSave: deleted and invalidated dentries can't be restored", genericDebugPathname(d.fs, d)))
 	}
 }
 
@@ -260,15 +260,15 @@ func (fd *specialFileFD) completeRestore(ctx context.Context) error {
 	d := fd.dentry()
 	h, err := d.openHandle(ctx, fd.vfsfd.IsReadable(), fd.vfsfd.IsWritable(), false /* trunc */)
 	if err != nil {
-		return fmt.Errorf("failed to open handle for specialFileFD for %q: %w", genericDebugPathname(d), err)
+		return fmt.Errorf("failed to open handle for specialFileFD for %q: %w", genericDebugPathname(d.fs, d), err)
 	}
 	fd.handle = h
 
 	ftype := d.fileType()
 	fd.haveQueue = (ftype == linux.S_IFIFO || ftype == linux.S_IFSOCK) && fd.handle.fd >= 0
 	if fd.haveQueue {
 		if err := fdnotifier.AddFD(fd.handle.fd, &fd.queue); err != nil {
-			return fmt.Errorf("failed to add FD to fdnotified for %q: %w", genericDebugPathname(d), err)
+			return fmt.Errorf("failed to add FD to fdnotified for %q: %w", genericDebugPathname(d.fs, d), err)
 		}
 	}
 

pkg/sentry/fsimpl/kernfs/BUILD

@@ -26,6 +26,7 @@ go_template_instance(
     template = "//pkg/sentry/vfs/genericfstree:generic_fstree",
     types = {
         "Dentry": "Dentry",
+        "Filesystem": "Filesystem",
     },
 )
 
@@ -86,10 +87,10 @@ go_template_instance(
 )
 
 declare_rwmutex(
-    name = "filesystem_mutex",
-    out = "filesystem_mutex.go",
+    name = "ancestry_mutex",
+    out = "ancestry_mutex.go",
     package = "kernfs",
-    prefix = "filesystem",
+    prefix = "ancestry",
 )
 
 declare_mutex(
@@ -99,9 +100,17 @@ declare_mutex(
     prefix = "deferredDecRefs",
 )
 
+declare_rwmutex(
+    name = "filesystem_mutex",
+    out = "filesystem_mutex.go",
+    package = "kernfs",
+    prefix = "filesystem",
+)
+
 go_library(
     name = "kernfs",
     srcs = [
+        "ancestry_mutex.go",
         "deferred_dec_refs_mutex.go",
         "dentry_list.go",
         "dynamic_bytes_file.go",

pkg/sentry/fsimpl/kernfs/filesystem.go

@@ -1089,9 +1089,12 @@ func (fs *Filesystem) RemoveXattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 
 // PrependPath implements vfs.FilesystemImpl.PrependPath.
 func (fs *Filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
-	fs.mu.RLock()
-	defer fs.mu.RUnlock()
-	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*Dentry), b)
+	return genericPrependPath(fs, vfsroot, vd.Mount(), vd.Dentry().Impl().(*Dentry), b)
+}
+
+// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
+func (fs *Filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
+	return genericIsDescendant(fs, vfsroot.Dentry(), vd.Dentry().Impl().(*Dentry))
 }
 
 func (fs *Filesystem) deferDecRefVD(ctx context.Context, vd vfs.VirtualDentry) {
@@ -1106,8 +1109,3 @@ func (fs *Filesystem) deferDecRefVD(ctx context.Context, vd vfs.VirtualDentry) {
 		vd.DecRef(ctx)
 	}
 }
-
-// IsDescendant implements vfs.FilesystemImpl.IsDescendant.
-func (fs *Filesystem) IsDescendant(vfsroot, vd vfs.VirtualDentry) bool {
-	return genericIsDescendant(vfsroot.Dentry(), vd.Dentry().Impl().(*Dentry))
-}