Re: [9front] Booting with encrypted partitions

Re: [9front] Booting with encrypted partitions

[cinap_lenrek]

notice that this mechanism has nothing specitic to
disk/cryptsetup and is just a hook to get arbitrary
code run.

which is *FINE*. just in the wrong place for something
like cryptsetup and has the wrong name.

you see the main function in bootrc can get run multiple
times. which is not what you'd want i think.

... also what Ori said, the empty test is wrong.

but otherwise i'm not against such a hook, which could
be usefull for other things as well.

probably do it right after the configlocal line in boorc.
(and dont forget the </dev/cons redirection to make
prompts work).

any suggestions for a good name? $start? $setup?
$autoexec? $DEVICEHIGH?

the name probably depends on what OTHER hooks we'r going
to add in some strategic places. any suggestions?

--
cinap

Re: [9front] Booting with encrypted partitions

[petter9]

Glad to see some interest! Just to be clear. My goal here was primarily 
just to hack together something that scratches my itch, today.


Thanks for pointing out the flaw with the empty test.  I actually had it 
there before, but it got lost retyping it after reinstalling.  (Yes, my 
process sucks.)


Ori: I did consider briefly to make it work automatically for different 
setups.

Some quick thoughts that put me off:
* What if new crypto programs are introduced. Which one to use.
* What if someone has multiple plan9 installations on the same disk 
and/or several disks.
* Different filesystems may need different partitions decrypted. 
Maintain a list? Update with new filesystems.
* Different filesystems and multiple installations.
* Should one decrypt before or after partition is selected.

Felt a bit like a pandora's box to me.  (Could very well be i'm making 
problems that aren't actually here obviously.  I don't know.)

Having the user specify the decryption command themselves is the 
simplest and cleanest solution i could think of, random unverified 
concerns considered.  Not saying having it in plan9.ini like that is the 
right way to do it.  (But hey, step 1: get something that works;))


Cinap: Regarding having this in the main loop.  The scenario i had in 
mind there was the user aborting the password input (DEL) to type in 
some other partition in bootargs (multi-boot/usb).  And if that fails, 
just start all over again.


I'd be happy to help and experiment the next few days before i set this 
computer to work.  I'll try moving it around.


initcmd?


--
Petter

--
For the record.

diff -r 8f9f3ee2eacf sys/src/9/boot/bootrc
--- a/sys/src/9/boot/bootrc	Mon Nov 11 13:35:47 2019 -0800
+++ b/sys/src/9/boot/bootrc	Tue Nov 12 13:10:09 2019 +0100
@@ -65,6 +65,11 @@
  mt=()
  
  fn main{
+	if(! ~ $#decryptfs 0) {
+		echo $decryptfs
+		eval $decryptfs
+	}
+
  	mp=()
  	while(~ $#mp 0){
  		if(~ $#nobootprompt 0){



---plan9.ini---
decryptfs=disk/cryptsetup -i /dev/sdE0/fsworm /dev/sdE0/fscache 
/dev/sdE0/other
nobootprompt=local!/dev/fs/fscache
mouseport=ps2
monitor=x200
vgasize=1280x800x32
user=p

Re: [9front] Booting with encrypted partitions

[petter9]

I like having the hook before the loop now too, as cinap suggested.  In 
the scenario of a user having a partition decryption command in this 
hook and aborting the password prompt; they can now try their different 
boot options without having an annoying password prompt appearing all 
the time.  (The prompt is just a reboot away should they want it again.)

diff -r 8f9f3ee2eacf sys/src/9/boot/bootrc
--- a/sys/src/9/boot/bootrc	Mon Nov 11 13:35:47 2019 -0800
+++ b/sys/src/9/boot/bootrc	Wed Nov 20 11:55:12 2019 +0100
@@ -186,6 +186,12 @@
  # add partitions and binds
  configlocal
  
+# execute hook 'startcmd' from plan9.ini
+if(! ~ $#startcmd 0) {
+	echo $startcmd
+	eval $startcmd
+}
+
  while(){
  	@{main}



I went with 'startcmd', which is still open for debate..


I can help with updating the fqa if something like this patch is committed.


Come to think of; there's also the possibility of having a bootrc.local 
(mimicking termrc and cpurc).  I actually think that seems like a better 
path going forward, but i haven't made any attempts at that.


--
Petter

Re: [9front] Booting with encrypted partitions

[hiro]

if more ideas are needed:
perhaps refer to the next thing it precedes: "pre-bootprompt" ?
doesn't seem to be convention here, but i like that on other OS's the
order of execution is sometimes visible e.g. by having a number
prefixed, or in the style of pre-something/post-something scripts or
interface-up/interface-down....

Re: [9front] Booting with encrypted partitions

[ori]

> any suggestions for a good name? $start? $setup?
> $autoexec? $DEVICEHIGH?

startcmd is the best I can think of.

Re: [9front] Booting with encrypted partitions

[ori]

> Hi,
> 
> Got a bit tired of dropping to the shell and punching in the disk 
> decryption command on every boot.  This one:
>  > disk/cryptsetup -i /dev/sdE0/fsworm /dev/sdE0/fscache /dev/sdE0/other
> Also, one typo and the entire command must be retyped :/

If you attach patches inline, it's easier to review, and they'll still
be viewable years from now.

> So i made a change to the boot process to do that for me. Don't know if 
> something like this exist but it was anyway educational for me doing 
> this (noob) and i just thought i would share in case anyone is interested.
> 
> The change to the boot script,
> http://okturing.com/src/7221/body

>  diff -r 8f9f3ee2eacf sys/src/9/boot/bootrc
>  --- a/sys/src/9/boot/bootrc     Mon Nov 11 13:35:47 2019 -0800
>  +++ b/sys/src/9/boot/bootrc     Tue Nov 12 13:10:09 2019 +0100
>  @@ -65,6 +65,11 @@
>   mt=()
>   
>   fn main{
>  +       if(! ~ $decryptfs 0) {

This line isn't quite right -- you're checking if the content of '$decryptfs'
is 0, rather than whether the list has 0 elements. You need the '#' operator:

	if(! ~ $#decryptfs 0)

Other than that, it like it will work to me.

I'll let someone else more familiar with the boot process (cinap,
probably?) comment if there's a cleaner solution that doesn't add a
new knob. Ideally, I think we'd want:

	nobootprompt=crypt!local!/dev/sdE0/fscache

but I don't see a great way to get the args for disk/cryptsetup
out of that spec.