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Date: Mon, 12 Jun 2017 20:15:06 +0200
From: Casper.Dik@...cle.com
To: oss-security@...ts.openwall.com
Subject: Re: Vixie/ISC Cron group crontab to root escalation 


>On Jun 9,  6:27pm, solar@...nwall.com (Solar Designer) wrote:
>-- Subject: Re: [oss-security] Vixie/ISC Cron group crontab to root escalatio
>
>| Oh, I did in fact mention this in the private discussion, so I'll quote:
>| 
>| | Another detail: somehow in Owl we introduced lstat() prior to open, and
>| | check lstat()'s struct for all the required properties before proceeding
>| | with open() with O_NOFOLLOW.  Then we check that st_dev/st_ino stayed
>| | the same.  We also kept the post-open() checks.  I don't recall exactly
>| | why we added this, but maybe because of the possibility of side-effects
>| | on open() for hard links to device files (like with tape drives).  And
>| | it looks like we neglected to add the same for at jobs (perhaps didn't
>| | revisit this when support for at jobs appeared via our update to later
>| | OpenBSD code) - maybe we should.
>
>Thanks, perhaps a comment in the code can't hurt...
>Or even O_NODEV which does not exist, or O_PATH (linux only)..

As there is a O_DIRECTORY it would be more orthogonal to have O_REGULAR 
(open only a regular file).  But that becomes more and more icky as we're 
running out of 32 bits of O_*)

Casper

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