From: Pavel Machek <pavel@ucw.cz>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@linux-foundation.org, linux-man@vger.kernel.org,
linux-api@vger.kernel.org, jmorris@namei.org,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down
Date: Fri, 13 Apr 2018 22:22:41 +0200 [thread overview]
Message-ID: <20180413202241.GB4484@amd> (raw)
In-Reply-To: <152346403637.4030.15247096217928429102.stgit@warthog.procyon.org.uk>
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On Wed 2018-04-11 17:27:16, David Howells wrote:
> Disallow opening of debugfs files that might be used to muck around when
> the kernel is locked down as various drivers give raw access to hardware
> through debugfs. Given the effort of auditing all 2000 or so files and
> manually fixing each one as necessary, I've chosen to apply a heuristic
> instead. The following changes are made:
>
> (1) chmod and chown are disallowed on debugfs objects (though the root dir
> can be modified by mount and remount, but I'm not worried about that).
This has nothing to do with the lockdown goals, right? I find chown of
such files quite nice, to allow debugging without doing sudo all the time.
> (2) When the kernel is locked down, only files with the following criteria
> are permitted to be opened:
>
> - The file must have mode 00444
> - The file must not have ioctl methods
> - The file must not have mmap
Dunno. Would not it be nicer to go through the debugfs files and split
them into safe/unsafe varieties?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-04-13 20:22 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 16:24 [PATCH 00/24] security: Add kernel lockdown David Howells
2018-04-11 16:24 ` [PATCH 01/24] Add the ability to lock down access to the running kernel image David Howells
2018-04-11 16:44 ` Jann Horn
2018-04-11 17:37 ` Randy Dunlap
2018-04-11 18:50 ` Miguel Ojeda
2018-04-11 19:56 ` Greg KH
2018-04-11 17:49 ` David Howells
2018-04-11 18:09 ` Linus Torvalds
2018-04-11 18:35 ` Justin Forbes
2018-04-11 21:05 ` Jordan Glover
2018-04-11 22:38 ` Linus Torvalds
2018-04-12 13:09 ` Justin Forbes
2018-04-12 16:52 ` Linus Torvalds
2018-04-12 2:57 ` Andy Lutomirski
2018-04-11 16:24 ` [PATCH 02/24] Add a SysRq option to lift kernel lockdown David Howells
2018-04-11 17:05 ` Jann Horn
2018-04-13 20:22 ` Pavel Machek
2018-04-11 16:24 ` [PATCH 03/24] ima: require secure_boot rules in lockdown mode David Howells
2018-04-11 16:25 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells
2018-04-11 16:25 ` [PATCH 05/24] Restrict /dev/{mem, kmem, port} when " David Howells
2018-04-11 16:25 ` [PATCH 06/24] kexec_load: Disable at runtime if " David Howells
2018-04-11 19:00 ` Eric W. Biederman
2018-04-11 20:09 ` Mimi Zohar
2018-04-12 11:38 ` Mimi Zohar
2018-04-11 20:05 ` David Howells
2018-04-11 16:25 ` [PATCH 07/24] hibernate: Disable when " David Howells
2018-04-13 20:22 ` Pavel Machek
2018-04-19 14:38 ` David Howells
2018-04-22 14:34 ` Andy Lutomirski
2018-04-26 7:26 ` Pavel Machek
2018-04-26 7:34 ` Rafael J. Wysocki
2018-04-26 8:20 ` Jiri Kosina
2018-05-23 8:46 ` joeyli
2018-04-11 16:25 ` [PATCH 08/24] uswsusp: " David Howells
2018-04-11 16:25 ` [PATCH 09/24] PCI: Lock down BAR access " David Howells
2018-04-11 16:25 ` [PATCH 10/24] x86: Lock down IO port " David Howells
2018-04-11 16:25 ` [PATCH 11/24] x86/msr: Restrict MSR " David Howells
2018-04-11 16:25 ` [PATCH 12/24] ACPI: Limit access to custom_method " David Howells
2018-04-11 16:26 ` [PATCH 13/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells
2018-04-11 16:26 ` [PATCH 14/24] acpi: Disable ACPI table override if the kernel is " David Howells
2018-04-11 16:26 ` [PATCH 15/24] acpi: Disable APEI error injection " David Howells
2018-04-11 16:26 ` [PATCH 16/24] Prohibit PCMCIA CIS storage when " David Howells
2018-04-11 16:26 ` [PATCH 17/24] Lock down TIOCSSERIAL David Howells
2018-04-11 16:26 ` [PATCH 18/24] Lock down module params that specify hardware parameters (eg. ioport) David Howells
2018-04-11 17:22 ` Randy Dunlap
2018-04-11 16:26 ` [PATCH 19/24] x86/mmiotrace: Lock down the testmmiotrace module David Howells
2018-04-11 16:26 ` [PATCH 20/24] Lock down /proc/kcore David Howells
2018-04-11 16:26 ` [PATCH 21/24] Lock down kprobes David Howells
2018-04-11 16:27 ` [PATCH 22/24] bpf: Restrict kernel image access functions when the kernel is locked down David Howells
2018-04-11 16:27 ` [PATCH 23/24] Lock down perf David Howells
2018-04-11 16:27 ` [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down David Howells
2018-04-11 17:26 ` Randy Dunlap
2018-04-11 18:50 ` Eric W. Biederman
2018-04-11 19:54 ` Greg KH
2018-04-11 20:08 ` David Howells
2018-04-11 20:09 ` David Howells
2018-04-11 20:33 ` Greg KH
2018-04-12 2:54 ` Andy Lutomirski
2018-04-12 8:23 ` Greg KH
2018-04-12 14:19 ` Andy Lutomirski
2018-04-13 20:22 ` Pavel Machek [this message]
2018-04-19 14:35 ` David Howells
2018-05-10 11:01 ` Pavel Machek
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