linux-kernel - Re: what is necessary for directory hard links

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]

Date:	Fri, 21 Jul 2006 14:49:12 -0400
From:	"Horst H. von Brand" <vonbrand@....utfsm.cl>
To:	"Joshua Hudson" <joshudson@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: what is necessary for directory hard links 

Joshua Hudson <joshudson@...il.com> wrote:
> This patch is the sum total of all that I had to change in the kernel
> VFS layer to support hard links to directories

Can't be done, as it creates the possibility of loops. The "only files can
be hardlinked" idea makes garbage collection (== deleting of unreachable
objects) simple: Just check the number of references.

Detecting unconnected subgraphs uses a /lot/ of memory; and much worse, you
have to stop (almost) all filesystem activity while doing it.

Besides, the flow "root down through directories" gives a natural order in
which to go locking stuff when needed; if there can be loops, the system
could easily deadlock.
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

-
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/