netdev - Re: [RFC][PATCH] netlink: Only check file credentials for implicit destinations

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Date:	Sun, 25 May 2014 17:32:55 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	"Jorge Boncompte [DTI2]" <jorge@...2.net>,
	Jiri Benc <jbenc@...hat.com>,
	David Miller <davem@...emloft.net>,
	Vivek Goyal <vgoyal@...hat.com>,
	Simo Sorce <ssorce@...hat.com>,
	"security@...nel.org" <security@...nel.org>,
	Network Development <netdev@...r.kernel.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Michael Kerrisk-manpages <mtk.manpages@...il.com>
Subject: Re: [RFC][PATCH] netlink: Only check file credentials for implicit destinations

On Sun, May 25, 2014 at 4:44 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> But I agree that since connect on sockets is really the equivalent of
> open on files, and unprivileged users can change where a socket is
> connected to, using a struct cred captured at connect() time is better
> than the struct cred captured at socket() time.

Ack. Conceptually, "connect/listen" really ends up being the
equivalent to pathname lookup, not so much "socket()", which just
mostly creates the placeholder for future work.

That would also be very much consistent with making "sendto" look at
current creds rather than cached creds (but only _if_ it has an
address, of course - using "sendto(... , NULL, 0)" should _not_
somehow be different from "send()"). So I think that from a
sensibility and "please explain the semantics to me" standpoint, that
would be sane semantics.

              Linus
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