April 19th, 2019

U2F and Firefox on Funtoo

U2F is pretty neat. It can be used locally on a machine for authentication and for two factor authentication on websites. There are even plugins for using it on WordPress powered websites. At the time this article was written, Firefox does not enable U2F by default. Though, that looks to be changing with Firefox 68.

Enable U2F in Firefox

Enabling U2F in Firefox is fairly straightforward. In the URL bar enter: about:config. Then search for u2f. There should be an entry: security.webauth.u2f, set it to true.

Install pam_u2f

However, simply enabling U2F in Firefox is not enough for a U2F device to work. To get everything working, pam_u2f needs to be installed. On Funtoo, this is quite simple:

emerge -av pam_u2f

After installing pam_u2f, Firefox should now be able to query your U2F key.

March 22nd, 2019

XDM/SDDM Slow Startup Followup

Posted by John Havlik in General

As reference previously, recently, the XPS 15 9530 had an issue in startup where the login prompt in the shell was available but XDM/SDDM did not start until several key presses later. Waiting for it to start was a futile effort—once waited over 30 minutes to no avail. A full system reinstall did not help either.

Digging into the dmesg output revealed something interesting:

[83.413293] random: crng init done
[83.413299] random: 7 urandom warning(s) missed due to ratelimiting

It was taking over a minute and a half for random to generate enough entropy. And, this was with the keyboard getting mashed! Apparently, this is a relatively common issue to run into.

Since the XPS 15 9530 has a Haswell core CPU with RDRAND instruction support, an easy way around this is to enable “Trust CPU Vendor” in the kernel config:

CONFIG_RANDOM_TRUST_CPU=y

Now, this is not without consequence. There is concern that Intel’s RDRAND implementation was inappropriately influenced by external parties. An alternative workaround is to install haveged. This has its own issues—it is a software solution to inflate entropy. Finally, on the Gentoo forums, the recommendation is to continue to mash the keyboard until userland applications are updated with to more appropriate entropy requirements.