linux-kernel - Re: [patch] x86, ptrace: require admin privileges for ptrace BTS extension

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]

Message-ID: <7c86c4470812220523y7ccca8cag40f758393017cf7c@mail.gmail.com>
Date:	Mon, 22 Dec 2008 14:23:38 +0100
From:	"stephane eranian" <eranian@...glemail.com>
To:	"Markus Metzger" <markus.t.metzger@...el.com>
Cc:	hpa@...or.com, linux-kernel@...r.kernel.org, mingo@...e.hu,
	tglx@...utronix.de, markus.t.metzger@...il.com, roland@...hat.com,
	akpm@...ux-foundation.org, mtk.manpages@...il.com,
	juan.villacis@...el.com
Subject: Re: [patch] x86, ptrace: require admin privileges for ptrace BTS extension

Markus,

On Mon, Dec 22, 2008 at 1:02 PM, Markus Metzger
<markus.t.metzger@...el.com> wrote:
> Require admin privileges for ptrace BTS extension.
>
Can you explain the motivations for this?

I thought the BTS extension was a per-process functionality.
So how come I can debug and single step my process without
admin privilege and I cannot capture its own branches. Does this
have to do with user vs. kernel execution of the proces (BTS
captures everything if I recall)?

Thanks.

>
> Reported-by: Ingo Molnar <mingo@...e.hu>
> Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>
> ---
>
> Index: gits/arch/x86/kernel/ptrace.c
> ===================================================================
> --- gits.orig/arch/x86/kernel/ptrace.c  2008-12-22 09:09:25.000000000 +0100
> +++ gits/arch/x86/kernel/ptrace.c       2008-12-22 11:03:01.000000000 +0100
> @@ -21,6 +21,7 @@
>  #include <linux/audit.h>
>  #include <linux/seccomp.h>
>  #include <linux/signal.h>
> +#include <linux/capability.h>
>
>  #include <asm/uaccess.h>
>  #include <asm/pgtable.h>
> @@ -742,6 +743,10 @@
>        struct ptrace_bts_config cfg;
>        int error = 0;
>
> +       error = -EPERM;
> +       if (!capable(CAP_SYS_ADMIN))
> +               goto errout;
> +
>        error = -EOPNOTSUPP;
>        if (!bts_cfg.sizeof_bts)
>                goto errout;
> ---------------------------------------------------------------------
> Intel GmbH
> Dornacher Strasse 1
> 85622 Feldkirchen/Muenchen Germany
> Sitz der Gesellschaft: Feldkirchen bei Muenchen
> Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer
> Registergericht: Muenchen HRB 47456 Ust.-IdNr.
> VAT Registration No.: DE129385895
> Citibank Frankfurt (BLZ 502 109 00) 600119052
>
> This e-mail and any attachments may contain confidential material for
> the sole use of the intended recipient(s). Any review or distribution
> by others is strictly prohibited. If you are not the intended
> recipient, please contact the sender and delete all copies.
>
>
--
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/