Re: [RFC][PATCH v3] Unprivileged: Disable raising of privileges

[Samir Bellabes <sam@synack.fr>]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> Well to be fair its random regurgitated security idea of every year or
> two.

true, last year the same kind of discussion occurs with the 'personal
firewall' aka a network MAC.
http://marc.info/?t=123247387500003&r=3&w=2
http://marc.info/?t=123187029200001&r=2&w=2

> More to the point - we have security_* hooks so this kind of continuous
> security proposal turdstream can stay out of the main part of the kernel.

indeed, LSM framework was design to be the abstraction tool. the 3
design rules were : 

0. truly generic, where using a different security model is merely a
   matter of loading a different kernel module;
1. conceptually simple, minimally invasive, and efficient; and
2. able to support the existing POSIX.1e capabilities logic as an
   optional security module.

so, 'minimally invasive' is keyword. what's why I don't understand the
purpose of this kind of patch, even if I see the goal to achieve:

 int security_socket_connect(struct socket *sock, struct sockaddr *address, int addrlen)
 {
-	return security_ops->socket_connect(sock, address, addrlen);
+	int ret = 0;
+
+	ret = security_ops->socket_connect(sock, address, addrlen);
+	if (ret)
+		goto out;
+
+#ifdef CONFIG_SECURITY_DISABLENETWORK
+	ret = disablenetwork_security_socket_connect(sock, address, addrlen);
+	if (ret)
+		goto out;
+#endif
+
+out:
+	return ret;
 }

This really seems to be a kind of stacking, but it's not. So are we
going to move LSM framework to support stacking, or are we respecting
the rules of LSM framework (respecting the abstract hooks) ?
This change makes LSM framework no more generic at all.