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From: Daniel Micay <danielmicay@gmail.com>
To: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [kernel-hardening] [PATCH 3/4] Make static usermode helper binaries constant
Date: Thu, 15 Dec 2016 19:14:22 -0500	[thread overview]
Message-ID: <1481847262.1054.3.camel@gmail.com> (raw)
In-Reply-To: <1481846720.1054.1.camel@gmail.com>

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> So for statics, I think `static const char *` wins due to allowing
> merging (although it doesn't matter here). For non-statics, you end up
> with extra pointer constants. Those could get removed, but Linux
> doesn't
> have -fvisibility=hidden and I'm not sure how clever linkers are.
> Maybe
> setting up -fvisibility=hidden to work with monolithic non-module-
> enabled builds could actually be realistic. Expect it'd remove a fair
> bit of bloat but not sure how much would need to be marked as non-
> hidden 
> other than the userspace ABI.

-fvisibility=hidden + LTO would be really awesome though, since that
doesn't depend on the cleverness of linkers. So much that could be
ripped out of real world monolithic builds. Kinda getting off-topic now
though. LTO is pretty scary from a security perspective due to how much
worse undefined behavior that was previously harmless can get.

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  reply	other threads:[~2016-12-16  0:14 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-14 18:50 [kernel-hardening] [RFC 0/4] make call_usermodehelper a bit more "safe" Greg KH
2016-12-14 18:50 ` [kernel-hardening] [PATCH 1/4] kmod: make usermodehelper path a const string Greg KH
2016-12-14 18:50 ` [kernel-hardening] [PATCH 2/4] drbd: rename "usermode_helper" to "drbd_usermode_helper" Greg KH
2016-12-14 18:50 ` [kernel-hardening] [PATCH 3/4] Make static usermode helper binaries constant Greg KH
2016-12-14 19:11   ` Greg KH
2016-12-14 20:29   ` Rich Felker
2016-12-14 20:54     ` Greg KH
2016-12-15 17:54       ` Greg KH
2016-12-15 20:51         ` Daniel Micay
2016-12-15 21:18           ` Greg KH
2016-12-16  0:05             ` Daniel Micay
2016-12-16  0:14               ` Daniel Micay [this message]
2016-12-14 18:51 ` [kernel-hardening] [RFC 4/4] Introduce CONFIG_READONLY_USERMODEHELPER Greg KH
2016-12-14 20:31   ` [kernel-hardening] " Kees Cook
2016-12-14 20:57     ` Greg KH
2016-12-14 19:25 ` [kernel-hardening] [RFC 0/4] make call_usermodehelper a bit more "safe" Mark Rutland
2016-12-14 20:16   ` Kees Cook
2016-12-14 21:28 ` Jason A. Donenfeld
2016-12-14 23:16   ` Greg Kroah-Hartman
2016-12-16  1:02 ` [kernel-hardening] " NeilBrown
2016-12-16 12:49   ` Greg KH
2016-12-19 13:34     ` Jiri Kosina
2016-12-20  9:27       ` Greg KH
2016-12-20 10:27         ` Jiri Kosina
2016-12-20 10:31           ` Jiri Kosina
2016-12-20 10:48             ` Greg KH

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