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Date: Thu, 31 Dec 2009 00:57:49 -0800 From: ebiederm@...ssion.com (Eric W. Biederman) To: Alan Cox <alan@...rguk.ukuu.org.uk> Cc: "Serge E. Hallyn" <serue@...ibm.com>, "Andrew G. Morgan" <morgan@...nel.org>, Bryan Donlan <bdonlan@...il.com>, Benny Amorsen <benny+usenet@...rsen.dk>, Michael Stone <michael@...top.org>, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, linux-security-module@...r.kernel.org, Andi Kleen <andi@...stfloor.org>, David Lang <david@...g.hm>, Oliver Hartkopp <socketcan@...tkopp.net>, Herbert Xu <herbert@...dor.apana.org.au>, Valdis Kletnieks <Valdis.Kletnieks@...edu>, Evgeniy Polyakov <zbr@...emap.net>, "C. Scott Ananian" <cscott@...ott.net>, James Morris <jmorris@...ei.org>, Bernie Innocenti <bernie@...ewiz.org>, Mark Seaborn <mrs@...hic-beasts.com>, Randy Dunlap <randy.dunlap@...cle.com>, Américo Wang <xiyou.wangcong@...il.com>, Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>, Samir Bellabes <sam@...ack.fr>, Casey Schaufler <casey@...aufler-ca.com>, Pavel Machek <pavel@....cz>, Al Viro <viro@...iv.linux.org.uk> Subject: Re: [RFC][PATCH v3] Unprivileged: Disable raising of privileges Alan Cox <alan@...rguk.ukuu.org.uk> writes: > On Wed, 30 Dec 2009 13:36:57 -0800 > ebiederm@...ssion.com (Eric W. Biederman) wrote: > >> Alan Cox <alan@...rguk.ukuu.org.uk> writes: >> >> >> Added bprm->nosuid to make remove the need to add >> >> duplicate error prone checks. This ensures that >> >> the disabling of suid executables is exactly the >> >> same as MNT_NOSUID. >> > >> > Another fine example of why we have security hooks so that we don't get a >> > kernel full of other "random security idea of the day" hacks. >> >> Well it comes from plan 9. Except there they just simply did not >> implement suid. What causes you to think dropping the ability >> to execute suid executables is a random security idea of the day? > > Well to be fair its random regurgitated security idea of every year or > two. > > More to the point - we have security_* hooks so this kind of continuous > security proposal turdstream can stay out of the main part of the kernel. > > Cleaning up the mechanism by which NOSUID is handled in kernel seems a > good idea. Adding wacky new prctls and gunk for it doesn't, and belongs > in whatever security model you are using via the security hooks. I am more than happy to make this a proper system call, instead of a prctl. The way this code is evolving that seems to be the clean way to handle this. No point in hiding the functionality away in a corner in shame. In my book SUID applications are the root of all evil. They are exploitable if you twist their environment in a way they have not hardened themselves against, and simply supporting them prevents a lot of good features from being used by ordinary applications. To get SUID out of my way I have to do something. A disable SUID from this process and it's children is a simple and direct way there. My other path is much more complicated. As this also has security related uses it seems even better as a feature. Eric -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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