linux-kernel - Re: [PATCH v3] vfs: new O

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20091207122346.6d18a8e1@lxorguk.ukuu.org.uk>
Date:	Mon, 7 Dec 2009 12:23:46 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	miklos@...redi.hu, luto@....edu, akpm@...ux-foundation.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] vfs: new O_NODE open flag

The standard udev unload is a true open barrier so has an implicit
revoke() caused by the fact you cannot keep a handle to the filename open
during the udev sequence (or the old driver would be pinned by a refcount
and not unload).

This isn't about hard links, its about object and handle lifetimes.
Ownership is also involved in the case of things like a tty device (so if
you can fchmod down the handle you can break the security model).

It only works because you have a true revoke (by virtue of refcounting in
the kernel driver modules)

Alan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/