linux-kernel - Re: [PATCH] nextfd(2)

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, 6 Apr 2012 23:16:02 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
	torvalds@...ux-foundation.org, drepper@...il.com,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] nextfd(2)

On Fri, Apr 06, 2012 at 09:14:17AM -0700, H. Peter Anvin wrote:
> On 04/06/2012 02:54 AM, Alexey Dobriyan wrote:
> > 
> > I agree, this particular changelog may be somewhat out of line.
> > 
> > But I find it little hypocritical that kernel developers add CONFIG_PROC_FS,
> > fix compilation problems associated with it, do not mount proc by default,
> > do not mark it unmountable somehow and
> > then say procless setups aren't worth it.
> > 
> 
> Aren't worth *optimizing for*.  But yes, CONFIG_PROC_FS is pretty much a
> historic relic at this point, and probably should just be dropped.

What to do with automounting /proc so it availablility would match
syscall availability?

> > Without proc knowledge about fdtable is gathered linearly and still unreliable.
> > With nextfd(2), even procful environments could lose several failure branches.
> 
> What?  Please explain how on Earth this would "lose several failure
> branches."

closefrom(3) written via nextfd(2) loop is reliable and doesn't fail.
closefrom(3) written via /proc/self/fd is reliable and can fail (including ENOMEM).
closefrom(3) written via close(fd++) is unreliable.

If programmer adds nextfd(2) loop before any closefrom(3) code
he currently uses, there will be less failures.
--
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/