linux-kernel - Re: O_NOLINK for open()

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:	Wed, 12 Sep 2007 14:46:41 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Brent Casavant <bcasavan@....com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: O_NOLINK for open()

Brent Casavant wrote:
> On Wed, 12 Sep 2007, H. Peter Anvin wrote:
> 
>> Brent Casavant wrote:
> 
>>> 	http://marc.info/?l=linux-kernel&m=93032806224160&w=2
>> This link talks about file flags handling.  I don't see the relevance to
>> this problem at all.  However, this is a very long thread, so if there
>> is anything specific that you want to point to, then please elucidate.
> 
> Oops, my mistake -- I pasted the wrong URL.  I meant this thread, this
> post in particular:
> 
> 	http://marc.info/?l=linux-kernel&m=88937224115435&w=2
> 
> Still, O_NOLINK would seem to be a valuable addition, and greatly
> simplify secure temporary file creation.
> 

Avoiding -- or at least detecting -- symlink racing with mkdir() is
relatively simple: run mkdir(), make sure you don't get EEXIST or
something like that, lstat() the resulting path -- it should be a
directory with all the right modes and ownerships.

I believe -- but I'm not certain -- that mkdtemp() in glibc will do all
this for you.  If not, I would consider that a glibc bug.

	-hpa
-
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/