[CentOS] Best configuration for encrypted software RAID 1?

Mon May 20 21:07:25 UTC 2013
SilverTip257 <silvertip257 at gmail.com>

On Fri, May 17, 2013 at 9:48 PM, Dave Johansen <davejohansen at gmail.com>wrote:

> On Fri, May 17, 2013 at 12:04 PM, SilverTip257 <silvertip257 at gmail.com>
> wrote:
> >
> > On Fri, May 17, 2013 at 12:42 PM, SilverTip257 <silvertip257 at gmail.com
> >wrote:
> >
> > > On Fri, May 17, 2013 at 11:21 AM, Dave Johansen <
> davejohansen at gmail.com>wrote:
> > >
> > >>
> > >> >
> > >> > [0] https://wiki.archlinux.org/index.php/Dm-crypt_with_LUKS
> > >>
> > >> Thanks for the feedback. I'm actually doing this through an Anaconda
> > >> config file and I'm using the following settings:
> > >>
> > >> part raid.boota --size=500 --ondisk sda
> > >> part raid.bootb --size=500 --ondisk sdb
> > >> raid /boot --fstype=ext4 --level=1 --device=md0 raid.boota raid.bootb
> > >> part raid.slasha --grow --size=500 --ondisk sda
> > >> part raid.slashb --grow --size=500 --ondisk sdb
> > >> raid / --fstype=ext4 --level=1 --encrypted --passphrase=<passphrase>
> > >> --device=md1 raid.slasha raid.slashb
> > >>
> > >> Is that the "right" way to do it? Or is there a configuration that
> > >> would work better?
> > >>
> > >
> > > That looks right.  Maybe somebody else will have a tip.
> > >
> >
> > You might also reference the advanced example here [0].
> >
> > [0]
> >
> http://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-kickstart2-options.html#s2-kickstart2-options-part-examples
>
> That example is helpful for the RAID stuff, but it doesn't show an
> example of encryption and so that's what my question is really about.
> Should the raid line have the encryption like I have in my example? Or
> should it be on each of the partitions? I'm just curious if there's a


It is impossible to encrypt /boot... (you only have one other partition =>
root)
Single LUKS volume = ease of management?  So I'm thinking LUKS with LVM
inside.

If you encrypt root, but don't encrypt swap you could be exposing data.
As far as I've seen if you encrypt root, then you encrypt swap and most/all
other partitions.  It really depends on what you want encrypted (remember
there will be some CPU cycles and additional I/O wait).


> pro/con to each of those options. My very basic/quick testing seemed
> to indicate that doing it on the raid line was the better solution,
>

** Where else would you place the encryption?  (Please list of scenarios.)
**

You'll notice I choose not to put the LUKS passphrase in plain text in the
kickstart config (Anaconda asks for one before partitioning the disks).

I have an example below with and without LVM.  I've done non-LVM encrypted
setups in the past, so I haven't tested that recently.  But the
raid+luks+lvm I kickstarted on a test VM (notice the virtio disks).


> but I was just wondering if anyone had experience with this?
>

# clears ALL partitions on ALL drives
clearpart --all --initlabel

# set up software raid arrays
part raid.01 --size=512 --asprimary --ondisk=vda
part raid.02 --size=512 --asprimary --ondisk=vdb
part raid.03 --size=1024 --asprimary --ondisk=vda
part raid.04 --size=1024 --asprimary --ondisk=vdb
part raid.05 --size=5120 --asprimary --grow --ondisk=vda
part raid.06 --size=5120 --asprimary --grow --ondisk=vdb

# set up partitions on the software raid array (no LVM)
#raid /boot --fstype=ext4 --level=RAID1 raid.01 raid.02
#raid swap --fstype=swap --level=RAID0 raid.03 raid.04 --encrypted
#raid / --fstype=ext4 --level=RAID1 raid.05 raid.06 --encrypted
#    #
# OR #
#    #
# set up partitions on the software raid array (with LVM)
raid /boot   --fstype=ext4 --device=md0 --level=RAID1 raid.01 raid.02
raid swap    --fstype=swap --device=md1 --level=RAID0 raid.03 raid.04
--encrypted
raid pv.01   --fstype=ext4 --device=md2 --level=RAID1 raid.05 raid.06
--encrypted

# actual LVM volume group and logical volumes
volgroup vg00 pv.01
logvol /       --vgname=vg00 --size=4096 --maxsize=6144 --grow
--fstype=ext4 --name=rootfs
logvol /home   --vgname=vg00 --size=512                 --grow
--fstype=ext4 --name=home



>
> Thanks,
> Dave
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>


I've noticed the same passphrase is used for both LUKS volumes (Anaconda
only asked for a passphrase once) -- swap and the LVM PV are separate
softraid MDs.

Hopefully this is helpful.

-- 
---~~.~~---
Mike
//  SilverTip257  //