ThinkFinger
Related articles
ThinkFinger is a driver for the SGS Thomson Microelectronics fingerprint reader found in older IBM/Lenovo ThinkPads.
ThinkWiki has a list of various fingerprint readers found in ThinkPads. Newer models using different readers might not work with ThinkFinger.
Contents
Installation
Install thinkfinger from the official repositories.
Configuration
TF-Tool
Use tf-tool to test ThinkFinger. You will have to run this as root because a direct access to the usb devices is needed. Run tf-tool --acquire to generate a test.bir and tf-tool --verify to see if it identifies you correctly. tf-tool --add-user <username> acquires and stores your fingerprint in /etc/pam_thinkfinger/username.bir, which is needed for an authentication with pam.
Pam
PAM is the Pluggable Authentication Module, invented by Sun.
/etc/pam.d/login
Change the file /etc/pam.d/login to look like this if you want to use your fingerprint to authenticate yourself on logon:
#%PAM-1.0 auth sufficient pam_thinkfinger.so auth required pam_unix.so use_first_pass nullok_secure account required pam_unix.so password required pam_unix.so session required pam_unix.so
/etc/pam.d/su
Change this file to confirm the su command with a finger-swipe!
#%PAM-1.0 auth sufficient pam_rootok.so auth sufficient pam_thinkfinger.so auth required pam_unix.so nullok_secure try_first_pass account required pam_unix.so session required pam_unix.so
/etc/pam.d/sudo
Change this file to confirm the sudo command with a finger-swipe!
#%PAM-1.0 auth sufficient pam_thinkfinger.so auth required pam_unix.so nullok_secure try_first_pass auth required pam_nologin.so
/etc/pam.d/xscreensaver
XScreensaver is a bit tricky. First, configure PAM with a file "/etc/pam.d/xscreensaver" containing :
auth sufficient pam_thinkfinger.so auth required pam_unix_auth.so try_first_pass
But it still wont work with only that because xscreensaver cannot read/write from /dev/misc/uinput and /dev/bus/usb*. A udev rule must be written to authorize a new group read/write access.
First, create a new group. I suggest "fingerprint":
> sudo groupadd fingerprint Add the user you want to be able to unlock xscreensaver with the fingerprint reader to the group: > sudo gpasswd -a <user> fingerprint
Don't forget to logout and login again!
Search for "uinput" and "bus/usb" in your udev rules directory :
> grep -in uinput /etc/udev/rules.d/* /etc/udev/rules.d/udev.rules:222:KERNEL=="uinput", NAME="misc/%k", SYMLINK+="%k" /etc/udev/rules.d/udev.rules:263:KERNEL=="uinput", NAME="input/%k" > grep -in "bus/usb" /etc/udev/rules.d/* /etc/udev/rules.d/udev.rules:318:SUBSYSTEM=="usb_device", ACTION=="add", PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev};printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", NAME="%c", MODE="0664" /etc/udev/rules.d/udev.rules:320:SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0664"
Now copy the previous lines (222, 318 and 320 from /etc/udev/rules.d/udev.rules) to a new udev rules file. I suggest /etc/udev/rules.d/99my.rules
KERNEL=="uinput", NAME="misc/%k", SYMLINK+="%k", MODE="0660", GROUP="fingerprint" SUBSYSTEM=="usb_device", ACTION=="add", PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev};printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", NAME="%c", MODE="0664", GROUP="fingerprint" SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0664", GROUP="fingerprint"
The difference between the rules in /etc/udev/rules.d/99my.rules and those in /etc/udev/rules.d/udev.rules should only be the addition of MODE="0664", GROUP="fingerprint" or MODE="0660", GROUP="fingerprint" at the end of the lines.
After this you must actually give your user permissions to access his own fingerprint file, this can be done as in the following:
> chown $USERNAME:root /etc/pam_thinkfinger/$USERNAME.bir > chmod 400 /etc/pam_thinkfinger/$USERNAME.bir > chmod o+x /etc/pam_thinkfinger
Yes that last one is opening up a directory for execution to everyone so if you are super paranoid you might consider that a security flaw, just putting the warning out there.
The last part is about xscreensaver. If you check xscreensaver file, you will see it is setuid to root :
> ls -l /usr/bin/xscreensaver -rwsr-sr-x 1 root root 217K aoû 2 20:47 /usr/bin/xscreensaver
Because of this, xscreensaver wont be able to unlock with the fingerprint reader. You need to remove the setuid root with :
> sudo chmod -s /usr/bin/xscreensaver > ls -l /usr/bin/xscreensaver -rwxr-xr-x 1 root root 217K aoû 2 20:47 /usr/bin/xscreensaver
That's it!
/etc/pam.d/gdm
[I am not an expert in PAMs but this works, This section may need corrections]
Edit /etc/pam.d/gdm as done in sections 3.1 and 3.2
add as the first line in the file: auth sufficient pam_thinkfinger.so
Modify: auth required pam_unix.so ==> auth required pam_unix.so use_first_pass nullok_secure
/etc/pam.d/xdm
Change /etc/pam.d/xdm to look like this:
#%PAM-1.0 auth sufficient pam_thinkfinger.so auth required pam_unix.so use_first_pass nullok_secure auth required pam_nologin.so auth required pam_env.so account required pam_unix.so password required pam_unix.so session required pam_unix.so session required pam_limits.so
SLiM
To have thinkfinger support for the SLiM Login Manager you need to activate PAM support:
Get the package source of the slim package from ABS and change the "make" line in the PKGBUILD:
make USE_PAM=1 || return 1
Rebuild the package and install it.
Then create a file /etc/pam.d/slim:
#%PAM-1.0 auth sufficient pam_thinkfinger.so auth requisite pam_nologin.so auth required pam_env.so auth required pam_unix.so account required pam_unix.so session required pam_limits.so session required pam_unix.so password required pam_unix.so
Now restart slim and swipe your finger.
Alternative fingerprint reader software
Fprint is an alternative fingerprint reader software that works with some of the newer ThinkPad fingerprint readers.
See also
- http://www.thinkwiki.org/wiki/Talk:How_to_enable_the_fingerprint_reader
- http://thinkfinger.sourceforge.net/
- https://bbs.archlinux.org/viewtopic.php?id=36134
- http://www.thinkwiki.org/wiki/How_to_enable_the_fingerprint_reader_with_ThinkFinger
- http://www.thinkwiki.org/index.php?title=Installing_Ubuntu_6.06_on_a_ThinkPad_T43#Fingerprint_Reader