lightdm-guest-session prevents launching pcscd on-demand

[Lauri Võsandi]

On Ubuntu 12.04 the pcscd daemon is launched on demand by libpcsclite. I believe it relies on the setgid bit on /usr/sbin/pcscd for the process to gain proper rights to create /var/run/pcscd/pcscd.pid and /var/run/pcscd/pcscd.comm. Ubuntu guest account Apparmor profile prevents setgid bit taking action which means that under guest account it is not possible to use smartcards.

Running pcscd -f as guest user results in:

00000000 pcscdaemon.c:520:main() cannot create /var/run/pcscd/pcscd.pid: Permission denied
00000559 winscard_msg_srv.c:121:InitializeSocket() Unable to bind common socket: Permission denied
00000565 pcscdaemon.c:574:main() Error initializing pcscd.
00000581 pcscdaemon.c:658:clean_temp_files() Cannot remove /var/run/pcscd/pcscd.comm: No such file or directory
00000592 pcscdaemon.c:663:clean_temp_files() Cannot remove /var/run/pcscd/pcscd.pid: No such file or directory
00000604 pcscdaemon.c:658:clean_temp_files() Cannot remove /var/run/pcscd/pcscd.comm: No such file or directory
00000614 pcscdaemon.c:663:clean_temp_files() Cannot remove /var/run/pcscd/pcscd.pid: No such file or directory

As regular user it works as expected and card reader is recognized by opensc-tool -l

This bug is closely related to #1329923 and actually most of the nature of the problem is described there.

As a workaround I have reverted /etc/init.d/pcscd to pre 1.6.0 behaviour by commenting out exit 0 as the file itself suggests by running: sed -i -e 's/^exit 0$/#exit 0/' /etc/init.d/pcscd

This just means that the on-demand feature is disabled by launching pcscd during boot and everything works as expected

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.