Merge release-20200622.1-67-gbd43368f4 (automated)

3 files changed, 38 insertions, 14 deletions

diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go
index 5d83fe363..8c7c8e1b3 100644
--- a/pkg/sentry/fsimpl/gofer/directory.go
+++ b/pkg/sentry/fsimpl/gofer/directory.go
@@ -85,6 +85,7 @@ func (d *dentry) createSyntheticChildLocked(opts *createSyntheticOpts) {
 	d2 := &dentry{
 		refs:      1, // held by d
 		fs:        d.fs,
+		ino:       d.fs.nextSyntheticIno(),
 		mode:      uint32(opts.mode),
 		uid:       uint32(opts.kuid),
 		gid:       uint32(opts.kgid),
@@ -184,13 +185,13 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) {
 		{
 			Name:    ".",
 			Type:    linux.DT_DIR,
-			Ino:     d.ino,
+			Ino:     uint64(d.ino),
 			NextOff: 1,
 		},
 		{
 			Name:    "..",
 			Type:    uint8(atomic.LoadUint32(&parent.mode) >> 12),
-			Ino:     parent.ino,
+			Ino:     uint64(parent.ino),
 			NextOff: 2,
 		},
 	}
@@ -226,7 +227,7 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) {
 				}
 				dirent := vfs.Dirent{
 					Name:    p9d.Name,
-					Ino:     p9d.QID.Path,
+					Ino:     uint64(inoFromPath(p9d.QID.Path)),
 					NextOff: int64(len(dirents) + 1),
 				}
 				// p9 does not expose 9P2000.U's DMDEVICE, DMNAMEDPIPE, or
@@ -259,7 +260,7 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) {
 			dirents = append(dirents, vfs.Dirent{
 				Name:    child.name,
 				Type:    uint8(atomic.LoadUint32(&child.mode) >> 12),
-				Ino:     child.ino,
+				Ino:     uint64(child.ino),
 				NextOff: int64(len(dirents) + 1),
 			})
 		}
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 7bcc99b29..cd5f5049e 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -214,9 +214,8 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
 		return nil, err
 	}
 	if child != nil {
-		if !file.isNil() && qid.Path == child.ino {
-			// The file at this path hasn't changed. Just update cached
-			// metadata.
+		if !file.isNil() && inoFromPath(qid.Path) == child.ino {
+			// The file at this path hasn't changed. Just update cached metadata.
 			file.close(ctx)
 			child.updateFromP9Attrs(attrMask, &attr)
 			return child, nil
@@ -1499,3 +1498,7 @@ func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDe
 	defer fs.renameMu.RUnlock()
 	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
 }
+
+func (fs *filesystem) nextSyntheticIno() inodeNumber {
+	return inodeNumber(atomic.AddUint64(&fs.syntheticSeq, 1) | syntheticInoMask)
+}
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 8e74e60a5..2b83094cd 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -110,6 +110,26 @@ type filesystem struct {
 	syncMu           sync.Mutex
 	syncableDentries map[*dentry]struct{}
 	specialFileFDs   map[*specialFileFD]struct{}
+
+	// syntheticSeq stores a counter to used to generate unique inodeNumber for
+	// synthetic dentries.
+	syntheticSeq uint64
+}
+
+// inodeNumber represents inode number reported in Dirent.Ino. For regular
+// dentries, it comes from QID.Path from the 9P server. Synthetic dentries
+// have have their inodeNumber generated sequentially, with the MSB reserved to
+// prevent conflicts with regular dentries.
+type inodeNumber uint64
+
+// Reserve MSB for synthetic mounts.
+const syntheticInoMask = uint64(1) << 63
+
+func inoFromPath(path uint64) inodeNumber {
+	if path&syntheticInoMask != 0 {
+		log.Warningf("Dropping MSB from ino, collision is possible. Original: %d, new: %d", path, path&^syntheticInoMask)
+	}
+	return inodeNumber(path &^ syntheticInoMask)
 }
 
 type filesystemOptions struct {
@@ -585,11 +605,11 @@ type dentry struct {
 	// Cached metadata; protected by metadataMu and accessed using atomic
 	// memory operations unless otherwise specified.
 	metadataMu sync.Mutex
-	ino        uint64 // immutable
-	mode       uint32 // type is immutable, perms are mutable
-	uid        uint32 // auth.KUID, but stored as raw uint32 for sync/atomic
-	gid        uint32 // auth.KGID, but ...
-	blockSize  uint32 // 0 if unknown
+	ino        inodeNumber // immutable
+	mode       uint32      // type is immutable, perms are mutable
+	uid        uint32      // auth.KUID, but stored as raw uint32 for sync/atomic
+	gid        uint32      // auth.KGID, but ...
+	blockSize  uint32      // 0 if unknown
 	// Timestamps, all nsecs from the Unix epoch.
 	atime int64
 	mtime int64
@@ -704,7 +724,7 @@ func (fs *filesystem) newDentry(ctx context.Context, file p9file, qid p9.QID, ma
 	d := &dentry{
 		fs:        fs,
 		file:      file,
-		ino:       qid.Path,
+		ino:       inoFromPath(qid.Path),
 		mode:      uint32(attr.Mode),
 		uid:       uint32(fs.opts.dfltuid),
 		gid:       uint32(fs.opts.dfltgid),
@@ -846,7 +866,7 @@ func (d *dentry) statTo(stat *linux.Statx) {
 	stat.UID = atomic.LoadUint32(&d.uid)
 	stat.GID = atomic.LoadUint32(&d.gid)
 	stat.Mode = uint16(atomic.LoadUint32(&d.mode))
-	stat.Ino = d.ino
+	stat.Ino = uint64(d.ino)
 	stat.Size = atomic.LoadUint64(&d.size)
 	// This is consistent with regularFileFD.Seek(), which treats regular files
 	// as having no holes.