Cups wont print to smb-shared printer requiring user authentication via kerberos

[Thomas Schweikle]

Setup:
- Print server part of an AD domain. Print server requires authentication.
- Ubuntu client with cups-server. The client is part of the AD domain. The client does not share printers (and never will).
- User authenticated by AD within the AD domain.
- Now user wants to print. Printer is set up:
<DefaultPrinter KONICA-MINOLTA-C364Series-OpenOffice-PPD>
UUID urn:uuid:85b0f3b3-67a2-3385-7fd2-57ac93c0f837
AuthInfoRequired none
Info KONICA MINOLTA C364e
Location E017
MakeModel KONICA MINOLTA C364SeriesPS(P)
DeviceURI smb://<server>/drucker-muc
PortMonitor tbcp
State Idle
StateTime 1576145797
ConfigTime 1576146371
Type 8401100
Accepting Yes
Shared No
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
OpPolicy default
ErrorPolicy retry-job
Option print-quality 3
</DefaultPrinter>

Since AuthInfoRequired is set to "none" cups thinks everyone can print and no authentication would be necessary. That's not true: the printer requires authentication. Maybe a bug.

This print server requires any user to be authenticated and have a kerberos ticket. This is true. The user has a kerberos ticket and this user is allowed to print. The users kerberos ticket cache is available in memory and in /tmp/krb5_<uid>.keytab. CUPS does not seem to take it into account. May be a bug too.

Changing "AuthInfoRequired" from "none" to "username,password" allows cups to print. But this has to be done editing /etc/cups/printers.conf. The web printer configuration just does not allow to set anything else than "none". This is a bug.

Documentation misses what "AuthInfoRequired" has to be set for if kerberos authentication will be used. This is a bug too!

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: cups 2.2.12-2ubuntu1
ProcVersionSignature: Ubuntu 5.3.0-24.26-generic 5.3.10
Uname: Linux 5.3.0-24-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
Date: Thu Dec 12 13:54:01 2019
InstallationDate: Installed on 2019-09-09 (93 days ago)
InstallationMedia: Xubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
Lpstat:
 device for KONICA-MINOLTA-C364Series-OpenOffice-PPD: smb://srvmfg02-muc.bfs.de/drucker-muc
 device for PDF: cups-pdf:/
Lsusb:
 Bus 002 Device 003: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
 Bus 002 Device 002: ID 0e0f:0003 VMware, Inc. Virtual Mouse
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: VMware, Inc. VMware Virtual Platform
Papersize: letter
PpdFiles:
 Error: command ['fgrep', '-H', '*NickName', '/etc/cups/ppd/PDF.ppd', '/etc/cups/ppd/KONICA-MINOLTA-C364Series-OpenOffice-PPD.ppd'] failed with exit code 2: grep: /etc/cups/ppd/PDF.ppd: Permission denied
 grep: /etc/cups/ppd/KONICA-MINOLTA-C364Series-OpenOffice-PPD.ppd: Permission denied
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-5.3.0-24-generic root=UUID=f99c1b40-4de7-4f4c-9d3f-c32918aa952c ro rootflags=subvol=@ quiet splash
SourcePackage: cups
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/29/2019
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: 6.00
dmi.board.name: 440BX Desktop Reference Platform
dmi.board.vendor: Intel Corporation
dmi.board.version: None
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 1
dmi.chassis.vendor: No Enclosure
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd07/29/2019:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:
dmi.product.name: VMware Virtual Platform
dmi.product.version: None
dmi.sys.vendor: VMware, Inc.

[Thomas Schweikle (tps)]

Solved upstream with later versions of cups