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From: Greg KH <gregkh@linuxfoundation.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Matthew Garrett <matthewgarrett@google.com>,
	James Morris <jmorris@namei.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	Linux API <linux-api@vger.kernel.org>,
	Matthew Garrett <mjg59@google.com>
Subject: Re: [PATCH V31 25/25] debugfs: Disable open() when kernel is locked down
Date: Wed, 27 Mar 2019 09:30:57 +0900	[thread overview]
Message-ID: <20190327003057.GA27311@kroah.com> (raw)
In-Reply-To: <CALCETrXDF2c2-gnOyNTnEn-uPAZp0AaSB_PB8e2y8jf7zo=Cyg@mail.gmail.com>

On Tue, Mar 26, 2019 at 12:20:24PM -0700, Andy Lutomirski wrote:
> On Tue, Mar 26, 2019 at 11:28 AM Matthew Garrett
> <matthewgarrett@google.com> wrote:
> >
> > From: Matthew Garrett <mjg59@google.com>
> >
> > debugfs has not been meaningfully audited in terms of ensuring that
> > userland cannot trample over the kernel. At Greg's request, disable
> > access to it entirely when the kernel is locked down. This is done at
> > open() time rather than init time as the kernel lockdown status may be
> > made stricter at runtime.
> 
> Ugh.  Some of those files are very useful.  Could this perhaps still
> allow O_RDONLY if we're in INTEGRITY mode?

Useful for what?  Debugging, sure, but for "normal operation", no kernel
functionality should ever require debugfs.  If it does, that's a bug and
should be fixed.

thanks,

greg k-h

  parent reply	other threads:[~2019-03-27  0:31 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-26 18:27 [PATCH V31 00/25] Add support for kernel lockdown Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 01/25] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 02/25] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 03/25] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 04/25] kexec_load: Disable at runtime if " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 05/25] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 06/25] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-06-21  6:34   ` Dave Young
2019-06-21 20:13     ` Matthew Garrett
2019-06-21 20:14       ` Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 07/25] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-06-21  6:43   ` Dave Young
2019-06-21 20:18     ` Matthew Garrett
2019-06-24  1:52       ` Dave Young
2019-06-24 21:06         ` Matthew Garrett
2019-06-24 21:27           ` Mimi Zohar
2019-06-25  0:02             ` Matthew Garrett
2019-06-25  1:46               ` Mimi Zohar
2019-06-25  2:51           ` Dave Young
2019-03-26 18:27 ` [PATCH V31 08/25] hibernate: Disable when " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 09/25] uswsusp: " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 10/25] PCI: Lock down BAR access " Matthew Garrett
2019-03-26 20:55   ` Andy Lutomirski
2019-03-26 21:19     ` Alex Williamson
2019-03-26 18:27 ` [PATCH V31 11/25] x86: Lock down IO port " Matthew Garrett
2019-03-26 20:56   ` Andy Lutomirski
2019-03-26 18:27 ` [PATCH V31 12/25] x86/msr: Restrict MSR " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 13/25] ACPI: Limit access to custom_method " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 14/25] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 15/25] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 16/25] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 17/25] Lock down TIOCSSERIAL Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 18/25] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 19/25] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-03-27 15:57   ` Steven Rostedt
2019-03-27 16:55     ` Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 20/25] Lock down /proc/kcore Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 21/25] Lock down kprobes when in confidentiality mode Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 22/25] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-03-26 19:21   ` Andy Lutomirski
2019-03-26 18:27 ` [PATCH V31 23/25] Lock down perf when " Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 24/25] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-03-26 18:27 ` [PATCH V31 25/25] debugfs: Disable open() when kernel is locked down Matthew Garrett
2019-03-26 19:20   ` Andy Lutomirski
2019-03-26 19:21     ` Matthew Garrett
2019-03-27  0:30     ` Greg KH [this message]
2019-03-27  4:29       ` Andy Lutomirski
2019-03-27  5:06         ` Greg KH
2019-03-27  5:29           ` Andy Lutomirski
2019-03-27  5:33             ` Greg KH
2019-03-27 16:53               ` James Morris
2019-03-27 17:39               ` Andy Lutomirski
2019-03-27 17:42                 ` Matthew Garrett
2019-03-27 18:29                   ` Greg KH
2019-03-27 18:31                 ` Greg KH
2019-03-27  0:31   ` Greg KH
2019-03-27  2:06     ` Matthew Garrett
2019-03-27  2:35       ` Greg KH

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