Re: [PATCH 2/5] seccomp: Introduce addfd ioctl to seccomp user notifier
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2020-05-25 00:05:49
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On Sun, May 24, 2020 at 04:39:39PM -0700, Sargun Dhillon wrote:
+static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
+{
+ int ret;
+
+ /*
+ * Remove the notification, and reset the list pointers, indicating
+ * that it has been handled.
+ */
+ list_del_init(&addfd->list);
+
+ ret = security_file_receive(addfd->file);
+ if (ret)
+ goto out;
+
+ if (addfd->fd >= 0) {
+ ret = replace_fd(addfd->fd, addfd->file, addfd->flags);
+ if (ret >= 0)
+ fput(addfd->file);
+ } else {
+ ret = get_unused_fd_flags(addfd->flags);
+ if (ret >= 0)
+ fd_install(ret, addfd->file);
Bad refcounting rules. *IF* we go with anything of that sort (and I'm not
convinced that the entire series makes sense), it's better to have more
uniform rules re reference consumption/disposal.
Make the destructor of addfd *ALWAYS* drop its reference. And have this
function go
if (addfd->fd >= 0) {
ret = replace_fd(addfd->fd, addfd->file, addfd->flags);
} else {
ret = get_unused_fd_flags(addfd->flags);
if (ret >= 0)
fd_install(ret, get_file(addfd->file));
}