5 files changed, 37 insertions, 7 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index b6cd3fbd7837..2860ab3ccc6b 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -300,7 +300,7 @@ static int ovl_set_size(struct ovl_fs *ofs,
 		.ia_size = stat->size,
 	};
 
-	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
+	return ovl_do_notify_change(ofs, upperdentry, &attr);
 }
 
 static int ovl_set_timestamps(struct ovl_fs *ofs, struct dentry *upperdentry,
@@ -313,7 +313,7 @@ static int ovl_set_timestamps(struct ovl_fs *ofs, struct dentry *upperdentry,
 		.ia_mtime = stat->mtime,
 	};
 
-	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
+	return ovl_do_notify_change(ofs, upperdentry, &attr);
 }
 
 int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
@@ -326,7 +326,7 @@ int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
 			.ia_valid = ATTR_MODE,
 			.ia_mode = stat->mode,
 		};
-		err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, &attr);
 	}
 	if (!err) {
 		struct iattr attr = {
@@ -334,7 +334,7 @@ int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
 			.ia_uid = stat->uid,
 			.ia_gid = stat->gid,
 		};
-		err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, &attr);
 	}
 	if (!err)
 		ovl_set_timestamps(ofs, upperdentry, stat);
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 3a870bc8366c..8f7917474ee2 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -514,7 +514,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 			.ia_mode = cattr->mode,
 		};
 		inode_lock(newdentry->d_inode);
-		err = notify_change(&init_user_ns, newdentry, &attr, NULL);
+		err = ovl_do_notify_change(ofs, newdentry, &attr);
 		inode_unlock(newdentry->d_inode);
 		if (err)
 			goto out_cleanup;
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 40210d6d451d..4527bb8d52ea 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -21,6 +21,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		struct iattr *attr)
 {
 	int err;
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
 	bool full_copy_up = false;
 	struct dentry *upperdentry;
 	const struct cred *old_cred;
@@ -77,7 +78,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 		inode_lock(upperdentry->d_inode);
 		old_cred = ovl_override_creds(dentry->d_sb);
-		err = notify_change(&init_user_ns, upperdentry, attr, NULL);
+		err = ovl_do_notify_change(ofs, upperdentry, attr);
 		revert_creds(old_cred);
 		if (!err)
 			ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d6405c2046ed..bc81f279b170 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -122,6 +122,35 @@ static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
 	return ovl_xattr_table[ox][ofs->config.userxattr];
 }
 
+/*
+ * When changing ownership of an upper object map the intended ownership
+ * according to the upper layer's idmapping. When an upper mount idmaps files
+ * that are stored on-disk as owned by id 1001 to id 1000 this means stat on
+ * this object will report it as being owned by id 1000 when calling stat via
+ * the upper mount.
+ * In order to change ownership of an object so stat reports id 1000 when
+ * called on an idmapped upper mount the value written to disk - i.e., the
+ * value stored in ia_*id - must 1001. The mount mapping helper will thus take
+ * care to map 1000 to 1001.
+ * The mnt idmapping helpers are nops if the upper layer isn't idmapped.
+ */
+static inline int ovl_do_notify_change(struct ovl_fs *ofs,
+				       struct dentry *upperdentry,
+				       struct iattr *attr)
+{
+	struct user_namespace *upper_mnt_userns = ovl_upper_mnt_userns(ofs);
+	struct user_namespace *fs_userns = i_user_ns(d_inode(upperdentry));
+
+	if (attr->ia_valid & ATTR_UID)
+		attr->ia_uid = mapped_kuid_user(upper_mnt_userns,
+						fs_userns, attr->ia_uid);
+	if (attr->ia_valid & ATTR_GID)
+		attr->ia_gid = mapped_kgid_user(upper_mnt_userns,
+						fs_userns, attr->ia_gid);
+
+	return notify_change(upper_mnt_userns, upperdentry, attr, NULL);
+}
+
 static inline int ovl_do_rmdir(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry)
 {
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 307a36af7b4f..432ef060d2ab 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -821,7 +821,7 @@ retry:
 
 		/* Clear any inherited mode bits */
 		inode_lock(work->d_inode);
-		err = notify_change(&init_user_ns, work, &attr, NULL);
+		err = ovl_do_notify_change(ofs, work, &attr);
 		inode_unlock(work->d_inode);
 		if (err)
 			goto out_dput;