Re: [PATCH v2] lkdtm/bugs: Don't expect thread termination without CONFIG_UBSAN_TRAP

From: Kees Cook
Date: Wed Apr 13 2022 - 17:21:35 EST


On Wed, Apr 13, 2022 at 05:01:31PM -0400, Konstantin Ryabitsev wrote:
> On Wed, Apr 13, 2022 at 06:29:36AM +0000, Christophe Leroy wrote:
> > I have a [patatt] section in .gitconfig which contains:
> > signingkey = ed25519:xxxxxxxx
> > selector = xxxxxxxx (the same value as above)
> >
> > What should I do now for you to get the key ? I don't even know where
> > the key is stored in my computer.
>
> Your key is stored in ~/.local/share/patatt, but you don't really need to do
> anything, Kees can do the following:
>
> b4 kr --show-keys 363b58690e907c677252467a94fe49444c80ea76.1649704381.git.christophe.leroy@xxxxxxxxxx

Ah-ha, excellent.

>
> For now, this just provides instructions on what to do with the key:
>
> christophe.leroy@xxxxxxxxxx: (unknown)
> keytype: ed25519
> pubkey: HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0=
> krpath: ed25519/csgroup.eu/christophe.leroy/20211009
> fullpath: /home/user/.local/share/b4/keyring/ed25519/csgroup.eu/christophe.leroy/20211009

"fullpath" seems misleading for my config, given:

[patatt]
...
keyringsrc = ~/korg/pgpkeys/.keyring

Shouldn't this report fullpath as:

/home/kees/korg/pgpkeys/.keyring/ed25519/csgroup.eu/christophe.leroy/20211009

And as a side note, should I prefer .local/share/b4/keyring over adding
keys to a branch of the kernel keyring git tree?

> ---
> For ed25519 keys:
> echo [pubkey] > [fullpath]
>
> So, for Kees to start being aware of your key, he needs to do:
>
> mkdir -p /home/user/.local/share/b4/keyring/ed25519/csgroup.eu/christophe.leroy
> echo HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= > /home/user/.local/share/b4/keyring/ed25519/csgroup.eu/christophe.leroy/20211009
>
> I know this is awkward and clunky right now. Future versions of b4 will
> streamline keyring management to make it a lot easier, I promise.

Thanks for this walk-through! I think I managed this in the past with
another ed25519 key, but I failed to figure it out this time. ;)

Now it works! :)

✓ [PATCH v2] lkdtm/bugs: Don't expect thread termination without
CONFIG_UBSAN_TRAP
+ Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
+ Link: https://lore.kernel.org/r/363b58690e907c677252467a94fe49444c80ea76.1649704381.git.christophe.leroy@xxxxxxxxxx
---
✓ Signed: ed25519/christophe.leroy@xxxxxxxxxx


--
Kees Cook