[Bug 1929101] [NEW] systemd-networkd can't set ip6tnl interface mode as any

[Yakov Shiryaev]

Public bug reported:

systemd-networkd provides "Mode=" configuration for a virtual device of
"Kind=ip6tnl". But setting mode to "any" doesn't work, tunnel mode stay
as ipv6/ipv6:

20/05/21 18:08:33 darkyman at mnt-myt-focal ~ > ip -6 tun show
ip6tnl0: ipv6/ipv6 remote :: local :: encaplimit 0 hoplimit inherit tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)

I'm expecting it to be in any/ipv6 mode like:

ip6tnl0: any/ipv6 remote :: local :: encaplimit 0 hoplimit inherit
tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)

Config file attached (00-ip6tnl0.netdev), I'm using systemd `systemd 245 (245.4-4ubuntu3.6)` on a `Ubuntu 20.04.2 LTS`.
Currently I'm using systemd service as a workaround this issue, which sets mode to "any" by calling

/usr/sbin/ip -6 tunnel change ip6tnl0 mode any

And that's what networkctl thinks about this tunnel interface

● 7: ip6tnl0                                                                 
             Link File: /usr/lib/systemd/network/99-default.link             
          Network File: /etc/systemd/network/01-ip6tnl0.network              
                  Type: tunnel6                                              
                 State: degraded (configured)
                   MTU: 9000 (min: 68, max: 65407)                           
  Queue Length (Tx/Rx): 1/1                                                  
               Address: fe80::3063:1eff:febf:8aaa                            

May 20 17:55:36 mnt-myt-focal.example.com systemd-udevd[1062]: ip6tnl0: Could not generate persistent MAC: No data available
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev ready
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev could not be created: Invalid argument
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: IPv6 successfully enabled
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Link UP
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained carrier
May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained IPv6LL

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "systemd-networkd ip6tnl configuration"
   https://bugs.launchpad.net/bugs/1929101/+attachment/5499022/+files/00-ip6tunl0.netdev

** Description changed:

  systemd-networkd provides "Mode=" configuration for a virtual device of
  "Kind=ip6tnl". But setting mode to "any" doesn't work, tunnel mode stay
  as ipv6/ipv6:
  
  20/05/21 18:08:33 darkyman at mnt-myt-focal ~ > ip -6 tun show
  ip6tnl0: ipv6/ipv6 remote :: local :: encaplimit 0 hoplimit inherit tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)
  
  I'm expecting it to be in any/ipv6 mode like:
  
  ip6tnl0: any/ipv6 remote :: local :: encaplimit 0 hoplimit inherit
  tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)
  
  Config file attached (00-ip6tnl0.netdev), I'm using systemd `systemd 245 (245.4-4ubuntu3.6)` on a `Ubuntu 20.04.2 LTS`.
  Currently I'm using systemd service as a workaround this issue, which sets mode to "any" by calling
  
  /usr/sbin/ip -6 tunnel change ip6tnl0 mode any
+ 
+ And that's what networkctl thinks about this tunnel interface
+ 
+ ● 7: ip6tnl0                                                                 
+              Link File: /usr/lib/systemd/network/99-default.link             
+           Network File: /etc/systemd/network/01-ip6tnl0.network              
+                   Type: tunnel6                                              
+                  State: degraded (configured)
+                    MTU: 9000 (min: 68, max: 65407)                           
+   Queue Length (Tx/Rx): 1/1                                                  
+                Address: fe80::3063:1eff:febf:8aaa                            
+ 
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-udevd[1062]: ip6tnl0: Could not generate persistent MAC: No data available
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev ready
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev could not be created: Invalid argument
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: IPv6 successfully enabled
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Link UP
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained carrier
+ May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained IPv6LL

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https://bugs.launchpad.net/bugs/1929101

Title:
  systemd-networkd can't set ip6tnl interface mode as any

Status in systemd package in Ubuntu:
  New

Bug description:
  systemd-networkd provides "Mode=" configuration for a virtual device
  of "Kind=ip6tnl". But setting mode to "any" doesn't work, tunnel mode
  stay as ipv6/ipv6:

  20/05/21 18:08:33 darkyman at mnt-myt-focal ~ > ip -6 tun show
  ip6tnl0: ipv6/ipv6 remote :: local :: encaplimit 0 hoplimit inherit tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)

  I'm expecting it to be in any/ipv6 mode like:

  ip6tnl0: any/ipv6 remote :: local :: encaplimit 0 hoplimit inherit
  tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)

  Config file attached (00-ip6tnl0.netdev), I'm using systemd `systemd 245 (245.4-4ubuntu3.6)` on a `Ubuntu 20.04.2 LTS`.
  Currently I'm using systemd service as a workaround this issue, which sets mode to "any" by calling

  /usr/sbin/ip -6 tunnel change ip6tnl0 mode any

  And that's what networkctl thinks about this tunnel interface

  ● 7: ip6tnl0                                                                 
               Link File: /usr/lib/systemd/network/99-default.link             
            Network File: /etc/systemd/network/01-ip6tnl0.network              
                    Type: tunnel6                                              
                   State: degraded (configured)
                     MTU: 9000 (min: 68, max: 65407)                           
    Queue Length (Tx/Rx): 1/1                                                  
                 Address: fe80::3063:1eff:febf:8aaa                            

  May 20 17:55:36 mnt-myt-focal.example.com systemd-udevd[1062]: ip6tnl0: Could not generate persistent MAC: No data available
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev ready
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: netdev could not be created: Invalid argument
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: IPv6 successfully enabled
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Link UP
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained carrier
  May 20 17:55:36 mnt-myt-focal.example.com systemd-networkd[1008]: ip6tnl0: Gained IPv6LL

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