linux-kernel - Re: fanotify as syscalls

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]

Date:	Tue, 22 Sep 2009 09:04:44 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Andreas Gruenbacher <agruen@...e.de>
cc:	Jamie Lokier <jamie@...reable.org>, Eric Paris <eparis@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Evgeniy Polyakov <zbr@...emap.net>,
	David Miller <davem@...emloft.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org,
	viro@...iv.linux.org.uk, alan@...ux.intel.com, hch@...radead.org
Subject: Re: fanotify as syscalls

On Tue, 22 Sep 2009, Andreas Gruenbacher wrote:

> The fatal flaw of syscall interception is race conditions: you look up a 
> pathname in your interception layer; then when you call into the proper 
> syscall, the kernel again looks up the same pathname. There is no way to 
> guarantee that you end up at the same object in both lookups. The security 
> and fsnotify hooks are placed in the appropriate spots to avoid exactly that.

Fatal? You mean, for this corner case that the anti-malware industry lived 
with for so much time (in Linux and Windows), you're prepared in pushing 
all the logic that is currently implemented into their modules, into the 
kernel?
This includes process whitelisting, path whitelisting, caches, userspace 
access API definition, and so on? On top of providing a generally more 
limited interception.
Why don't we instead offer a lower and broader level of interception, 
letting the users decide if such fatal flaw needs to be addressed or 
not, in their modules?
They get a broader inteception layer, with the option to decide if or if 
not address certain scenarios, and we get less code inside the kernel.
A win/win situation, if you ask me.

- Davide

--
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/