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This change has been made by an automated script, maintained by the
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** Changed in: linux (Ubuntu)
       Status: New => Incomplete

** Tags added: eoan

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https://bugs.launchpad.net/bugs/1862858

Title:
  CIFS acesses DFS referral with wrong Kerberos ticket

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  kubuntu 19.10 with kernel 5.3.0-29-generic and64.

  This looks like a regression in the kernel CIFS module after the 4.15 & 5.0 
kernels.
  These earlier kernels follow the DFS referrals without error.

  The problem:
  - Use mount.cifs with kerberos authentication to mount a samba server hosting 
a DFS root.
    You will get a KRB ticket for the "dfs_root" machine.
  - Attempt to access a host a host via a DFS referral (call this "target_host")
  - Access will fail with "Permission Denied".
  - Use Wireshark to monitor CIFS and KRB traffic.
  - The kernel attempts to authenticate to "target_host" using the KRB ticket 
for "dfs_root".
  Note:
   - A DFS target running Win2008R2 will reply with 
STATUS_MORE_PROCESSING_REQUIRED, then the
     kernel will get a KRB ticket for "target_host" and use it.
     The connection is then successful.
   - A DFS target running Samba 4.7.6 will reply with STATUS_LOGON_FAILURE.
     The connection fails.

  Expected Result:
  - Successful connection.
  - The kernel should get a KRB ticket for "target_host" and use it.
    (This is what kernels 4.15 and 5.0 do [and a Windows client])

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