No interface to access Network Security Service database (nssdb)

[Eero Aaltonen]

Prompted by the fact that after upgrade to Ubuntu 22.04, smart card authentication in the firefox snap is no longer working.

I have an already configured Network Security Services database in ${HOME}/.pki/nssdb with OpenSC
( https://github.com/OpenSC/OpenSC ) library /usr/lib/x86_64-linux-gnu/opensc-pkcs11.so registered as a PKCS#11 module.

Listing certificates from my token with `certutil -d sql:${HOME}/.pki/nssdb -L -h TOKEN_LABEL` works normally.

It seems that the firefox snap is unable to access the .pki directory; attempting to access file:///home/USER/.pki/ results in "Access to the file was denied" message.

I also did not spot any interfaces in
https://snapcraft.io/docs/network-interfaces
or
https://snapcraft.io/docs/security-interfaces
related to Network Security Services

My impression is that this would require either:
A) adding an interface to access the users current NSSDB
B) adding a new isolated but persistent nssdb to the firefox snap.

I'll note that Evolution is a second application using nssdb, and it works normally.