1 files changed, 47 insertions, 3 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index b288843e6b42..37300e972a39 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -162,7 +162,8 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
 	enum ovl_path_type type;
 	struct path realpath;
 	const struct cred *old_cred;
-	bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
+	struct inode *inode = d_inode(dentry);
+	bool is_dir = S_ISDIR(inode->i_mode);
 	int fsid = 0;
 	int err;
 	bool metacopy_blocks = false;
@@ -175,6 +176,9 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
 	if (err)
 		goto out;
 
+	/* Report the effective immutable/append-only STATX flags */
+	generic_fill_statx_attr(inode, stat);
+
 	/*
 	 * For non-dir or same fs, we use st_ino of the copy up origin.
 	 * This guaranties constant st_dev/st_ino across copy up.
@@ -542,6 +546,7 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
 	struct inode *inode = d_inode(dentry);
 	struct path upperpath;
 	const struct cred *old_cred;
+	unsigned int flags;
 	int err;
 
 	err = ovl_want_write(dentry);
@@ -553,15 +558,49 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
 		ovl_path_real(dentry, &upperpath);
 
 		old_cred = ovl_override_creds(inode->i_sb);
-		err = ovl_real_fileattr_set(&upperpath, fa);
+		/*
+		 * Store immutable/append-only flags in xattr and clear them
+		 * in upper fileattr (in case they were set by older kernel)
+		 * so children of "ovl-immutable" directories lower aliases of
+		 * "ovl-immutable" hardlinks could be copied up.
+		 * Clear xattr when flags are cleared.
+		 */
+		err = ovl_set_protattr(inode, upperpath.dentry, fa);
+		if (!err)
+			err = ovl_real_fileattr_set(&upperpath, fa);
 		revert_creds(old_cred);
-		ovl_copyflags(ovl_inode_real(inode), inode);
+
+		/*
+		 * Merge real inode flags with inode flags read from
+		 * overlay.protattr xattr
+		 */
+		flags = ovl_inode_real(inode)->i_flags & OVL_COPY_I_FLAGS_MASK;
+
+		BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
+		flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
+		inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
 	}
 	ovl_drop_write(dentry);
 out:
 	return err;
 }
 
+/* Convert inode protection flags to fileattr flags */
+static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
+{
+	BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
+	BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
+
+	if (inode->i_flags & S_APPEND) {
+		fa->flags |= FS_APPEND_FL;
+		fa->fsx_xflags |= FS_XFLAG_APPEND;
+	}
+	if (inode->i_flags & S_IMMUTABLE) {
+		fa->flags |= FS_IMMUTABLE_FL;
+		fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
+	}
+}
+
 int ovl_real_fileattr_get(struct path *realpath, struct fileattr *fa)
 {
 	int err;
@@ -584,6 +623,7 @@ int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 
 	old_cred = ovl_override_creds(inode->i_sb);
 	err = ovl_real_fileattr_get(&realpath, fa);
+	ovl_fileattr_prot_flags(inode, fa);
 	revert_creds(old_cred);
 
 	return err;
@@ -1136,6 +1176,10 @@ struct inode *ovl_get_inode(struct super_block *sb,
 		}
 	}
 
+	/* Check for immutable/append-only inode flags in xattr */
+	if (upperdentry)
+		ovl_check_protattr(inode, upperdentry);
+
 	if (inode->i_state & I_NEW)
 		unlock_new_inode(inode);
 out: