linux-kernel - Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation, pathname matching

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20070616002012.GH2616@elf.ucw.cz>
Date:	Sat, 16 Jun 2007 02:20:12 +0200
From:	Pavel Machek <pavel@....cz>
To:	david@...g.hm
Cc:	Greg KH <greg@...ah.com>, Crispin Cowan <crispin@...ell.com>,
	Andreas Gruenbacher <agruen@...e.de>,
	Stephen Smalley <sds@...ho.nsa.gov>, jjohansen@...e.de,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation, pathname matching

Hi!

> >>Under the restorecon proposal, the web site would be horribly broken
> >>until restorecon finishes, as various random pages are or are not
> >>accessible to Apache.
> >
> >Usually you don't do that by doing a 'mv' otherwise you are almost
> >guaranteed stale and mixed up content for some period of time, not to
> >mention the issues surrounding paths that might be messed up.
> 
> on the contrary, useing 'mv' is by far the cleanest way to do this.
> 
> mv htdocs htdocs.old;mv htdocs.new htdocs
> 
> this makes two atomic changes to the filesystem, but can generate 
> thousands to millions of permission changes as a result.

Ok, so mv gets slower for big trees... and open() gets faster for deep
trees. Previously, open in current directory was one atomic read of
directory entry, now it has to read directory, and its parent, and its
parent parent, and its...

(Or am I wrong and getting full path does not need to bring anything
in, not even in cache-cold case?)

So, proposed solution has different performance tradeoffs, but should
still be a win -- opens are more common than moves.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
-
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/