[Bug 1612135] [NEW] CIFS client: access problems after updating to kernel 4.4.0-3*-generic

[Chris van Run]

Public bug reported:

Expected: being able to mount subfilesystems via cifs mount.
What happens: permission denied even though there is permission

I am denied access to the subfilesystems on a samba server. The top
level filesystem itself is unaffected but dfs links seem to run into
'Operation not permitted' problems. When accessing the subfilesystem on
the mount as root it mounts correctly. The standard user is then also
able to access the subfilesystem.

This only happens when the client uses kernel 4.4.0-34 (#53). When I
revert my client to an older kernel (4.4.0-21) everything works. Using
the older kernel the normal user can directly ls into the subfilesystem.

This is bug is very similar to bug #1603719
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1603719). However,
the released fix (in 4.4.0-33.52) does not seem to fix it for cifs.

Extra info:
Ubuntu 16.04.1 LTS
cifs-utils version: 2:6.4-1ubuntu1
Mount options are minimal: sec=krb5,uid=XXXX,cruid=XXX

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.15
ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
Uname: Linux 4.4.0-34-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: KDE
Date: Thu Aug 11 10:32:20 2016
InstallationDate: Installed on 2016-04-28 (104 days ago)
InstallationMedia: Kubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.update-motd.d.91-release-upgrade: [deleted]

** Affects: cifs-utils (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug cifs-utils xenial

** Package changed: ubuntu-release-upgrader (Ubuntu) => cifs-utils
(Ubuntu)

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https://bugs.launchpad.net/bugs/1612135

Title:
  CIFS client: access problems after updating to kernel 4.4.0-3*-generic

Status in cifs-utils package in Ubuntu:
  New

Bug description:
  Expected: being able to mount subfilesystems via cifs mount.
  What happens: permission denied even though there is permission

  I am denied access to the subfilesystems on a samba server. The top
  level filesystem itself is unaffected but dfs links seem to run into
  'Operation not permitted' problems. When accessing the subfilesystem
  on the mount as root it mounts correctly. The standard user is then
  also able to access the subfilesystem.

  This only happens when the client uses kernel 4.4.0-34 (#53). When I
  revert my client to an older kernel (4.4.0-21) everything works. Using
  the older kernel the normal user can directly ls into the
  subfilesystem.

  This is bug is very similar to bug #1603719
  (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1603719).
  However, the released fix (in 4.4.0-33.52) does not seem to fix it for
  cifs.

  Extra info:
  Ubuntu 16.04.1 LTS
  cifs-utils version: 2:6.4-1ubuntu1
  Mount options are minimal: sec=krb5,uid=XXXX,cruid=XXX

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ubuntu-release-upgrader-core 1:16.04.15
  ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
  Uname: Linux 4.4.0-34-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: KDE
  Date: Thu Aug 11 10:32:20 2016
  InstallationDate: Installed on 2016-04-28 (104 days ago)
  InstallationMedia: Kubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  PackageArchitecture: all
  ProcEnviron:
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: ubuntu-release-upgrader
  Symptom: ubuntu-release-upgrader
  UpgradeStatus: No upgrade log present (probably fresh install)
  modified.conffile..etc.update-motd.d.91-release-upgrade: [deleted]

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