+int may_setattr(struct user_namespace *mnt_userns, struct inode *inode,
+ unsigned int ia_valid)
+{
+ int error;
+
+ if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ return -EPERM;
+ }
+
+ /*
+ * If utimes(2) and friends are called with times == NULL (or both
+ * times are UTIME_NOW), then we need to check for write permission
+ */
+ if (ia_valid & ATTR_TOUCH) {
+ if (IS_IMMUTABLE(inode))
+ return -EPERM;
+
+ if (!inode_owner_or_capable(mnt_userns, inode)) {
+ error = inode_permission(mnt_userns, inode, MAY_WRITE);
+ if (error)
+ return error;
+ }
+ }
+ return 0;
+}
+EXPORT_SYMBOL(may_setattr);
+