linux-kernel - Re: [PATCH] Don't mlock guardpage if the stack is growing up

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: <4DCA4C05.4030803@redhat.com>
Date:	Wed, 11 May 2011 10:42:45 +0200
From:	Milan Broz <mbroz@...hat.com>
To:	Alasdair G Kergon <agk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Matthew Wilcox <matthew@....cx>,
	Zdenek Kabelac <zkabelac@...hat.com>,
	Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>,
	linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org,
	Hugh Dickins <hughd@...gle.com>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH] Don't mlock guardpage if the stack is growing up

On 05/11/2011 12:57 AM, Alasdair G Kergon wrote:
> (What other software packages make use of mlockall() and under what
> circumstances?)

Another one is cryptsetup for commands which manipulate with keys
in memory.
(Users of libcryptetup library are not forced to lock memory, it is optional
call. But cryptsetup itself as libcryptsetup library user always locks memory.)

And I am not happy with mlockall() as well but the lvm2 workaround
is quite complicated.

Basically it wants to lock memory with explicitly allocated keys
(this can be rewritten to use specific locked page though) but it
also need to lock various libdevmapper buffers when issuing dmcrypt
cfg ioctl (mapping table and messages contains key). So that's why
mlockall(MCL_CURRENT|MCL_FUTURE) was the simplest way (and no problems
reported yet).
(No that it is perfect but better than nothing... Of course
more important is to wipe memory with keys after use.)

Milan
--
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/