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From: Jordan Glover <Golden_Miller83@protonmail.ch>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	"greg@kroah.com" <greg@kroah.com>,
	Kees Cook <keescook@google.com>,
	"salyzyn@android.com" <salyzyn@android.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"kernel-team@android.com" <kernel-team@android.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH] tracing: do not leak kernel addresses
Date: Fri, 27 Jul 2018 08:07:13 -0400	[thread overview]
Message-ID: <753E9YR1QhdsPhsFoYuXCwfUzfyntDrc_A93hMUkktMi7lbh3KUZMcbfqKVWUfi15zYhuiDFant-ROa4QNV5shx74ff4hGngq2BOJDv-hq4=@protonmail.ch> (raw)
In-Reply-To: <20180726181558.25a5c3b8@gandalf.local.home>

On July 27, 2018 12:15 AM, Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 26 Jul 2018 09:52:11 -0700
> Nick Desaulniers ndesaulniers@google.com wrote:
>
> > See the section "Kernel addresses" in
> > Documentation/security/self-protection. IIRC, the issue is that a
> > process may have CAP_SYSLOG but not necessarily CAP_SYS_ADMIN (so it
> > can read dmesg, but not necessarily issue a sysctl to change
> > kptr_restrict), get compromised and used to leak kernel addresses,
> > which can then be used to defeat KASLR.
>
> But the code doesn't go to dmesg. It's only available
> via /sys/kernel/debug/tracing/printk_formats which is only available
> via root. Nobody else has access to that directory.
>
> -- Steve

I think the point was that when we take capabilities into account the root
privileges aren't unequivocal anymore. The 'root' owned process with only
'CAP_SYSLOG' shouldn't have access to /sys/kernel/debug/tracing/printk_formats

Jordan

  reply	other threads:[~2018-07-27 12:07 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 20:22 [PATCH] tracing: do not leak kernel addresses Mark Salyzyn
2018-07-25 21:14 ` Nick Desaulniers
2018-07-26  1:07 ` Steven Rostedt
2018-07-26 15:14   ` Mark Salyzyn
2018-07-26 15:22     ` Steven Rostedt
2018-07-26 16:32       ` Nick Desaulniers
2018-07-26 16:37         ` Steven Rostedt
2018-07-26 16:59           ` Nick Desaulniers
2018-07-26 21:56             ` Nick Desaulniers
2018-07-26 15:31     ` Greg KH
2018-07-26 16:52       ` Nick Desaulniers
2018-07-26 22:15         ` Steven Rostedt
2018-07-27 12:07           ` Jordan Glover [this message]
2018-07-27 13:40             ` Jann Horn
2018-07-27 13:47               ` Steven Rostedt
2018-07-27 18:13                 ` Nick Desaulniers
2018-07-27 18:31                   ` Steven Rostedt
     [not found]                     ` <CAMx4XWv3OazvURuN1XU2+5C5tNDzPuTniMn_T=XTA4P8_uwS_A@mail.gmail.com>
2018-07-27 18:47                       ` Jann Horn
2018-07-27 18:58                         ` Jann Horn
2018-07-27 19:54                           ` Theodore Y. Ts'o
2018-07-27 20:11                             ` Steven Rostedt
2018-07-27 20:21                               ` Theodore Y. Ts'o
2018-07-27 20:53                                 ` Steven Rostedt
2018-07-27 22:05                                 ` Sandeep Patil
2018-07-28  0:04                                   ` Theodore Y. Ts'o
2018-07-30 14:35                                     ` Sandeep Patil

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