[Bug 1845909] Re: [SRU] IPv6 link local address is assigned even when LinkLocalAddressing=no|ipv4

[Dan Streetman]

** Description changed:

  [impact]
  
- when a networkd interface is configured with LinkLocalAddressing=no,
- networkd still assigns a link-local address to it
+ in some situations when a networkd interface is configured with
+ LinkLocalAddressing=no, networkd still assigns a link-local address to
+ it
  
  [test case]
  
  see comment 3.
  
  note I was only able to reproduce this at boot time; if the vlan
  interface is removed (i.e. 'sudo ip l del pppoe') and then networkd
  restarted, the pppoe interface is created and does not have a link-local
- address.
+ address.  This is due to this bug being triggered by timing, as a vlan
+ interface is raised by the kernel when its parent interface is raised,
+ in this case by networkd itself.
  
  [regression potential]
  
- this moves the point when ipv6ll is configured; regressions would most
- likely involve failure to correctly configure an ipv6ll address when
- desired.
+ this changes how ipv6ll addresses are managed and dropped, as well as
+ changing when foreign addresses are dropped (later in config process).
+ Any regressions would likely be around incorrectly setting ipv6ll
+ addresses, or complete failure to complete interface configuration.
+ 
+ [scope]
+ 
+ this is fixed upstream by:
+ https://github.com/systemd/systemd/pull/13927
+ 
+ and also requires the upstream PR referenced in the original description:
+ upstream patch: https://github.com/systemd/systemd/pull/13565
+ 
+ this is required for focal (uploaded already), eoan, and bionic.  It may
+ be required for xenial.
  
  [other info]
  
- this bug was attempted to be fixed by 'debian/patches/networkd-honour-LinkLocalAddressing.patch' from upstream issue 9890, using a commit that does not correctly fix the issue and was never accepted upstream:
- https://github.com/systemd/systemd/issues/9890#issuecomment-455168751
- 
- this SRU completely reverts that patch, and adds the correct fix which
- was merged upstream:
- https://github.com/systemd/systemd/commit/0e2fdb83bb5e22047e0c7cc058b415d0e93f02cf
- 
- that commit is already included in Eoan so this sru is needed only for
- Disco.
+ Note, the original description below is incorrect, the issue/patch it
+ references is not enough to fix this issue.
  
  original description:
  
  --
  
  upstream issue: https://github.com/systemd/systemd/issues/12886
  upstream patch: https://github.com/systemd/systemd/pull/13565
  
  The upstream fix will be available in systemd 244.
  Backport please. Thanks.

** Changed in: systemd (Ubuntu Eoan)
       Status: Incomplete => In Progress

** Changed in: systemd (Ubuntu Bionic)
       Status: Incomplete => In Progress

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https://bugs.launchpad.net/bugs/1845909

Title:
  [SRU] IPv6 link local address is assigned even when
  LinkLocalAddressing=no|ipv4

Status in systemd:
  New
Status in systemd package in Ubuntu:
  In Progress
Status in systemd source package in Bionic:
  In Progress
Status in systemd source package in Disco:
  Won't Fix
Status in systemd source package in Eoan:
  In Progress
Status in systemd source package in Focal:
  In Progress

Bug description:
  [impact]

  in some situations when a networkd interface is configured with
  LinkLocalAddressing=no, networkd still assigns a link-local address to
  it

  [test case]

  see comment 3.

  note I was only able to reproduce this at boot time; if the vlan
  interface is removed (i.e. 'sudo ip l del pppoe') and then networkd
  restarted, the pppoe interface is created and does not have a link-
  local address.  This is due to this bug being triggered by timing, as
  a vlan interface is raised by the kernel when its parent interface is
  raised, in this case by networkd itself.

  [regression potential]

  this changes how ipv6ll addresses are managed and dropped, as well as
  changing when foreign addresses are dropped (later in config process).
  Any regressions would likely be around incorrectly setting ipv6ll
  addresses, or complete failure to complete interface configuration.

  [scope]

  this is fixed upstream by:
  https://github.com/systemd/systemd/pull/13927

  and also requires the upstream PR referenced in the original description:
  upstream patch: https://github.com/systemd/systemd/pull/13565

  this is required for focal (uploaded already), eoan, and bionic.  It
  may be required for xenial.

  [other info]

  Note, the original description below is incorrect, the issue/patch it
  references is not enough to fix this issue.

  original description:

  --

  upstream issue: https://github.com/systemd/systemd/issues/12886
  upstream patch: https://github.com/systemd/systemd/pull/13565

  The upstream fix will be available in systemd 244.
  Backport please. Thanks.

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