From upstream's changelog:

  * main: annotate init/exit functions to save memory
  * selftest: remove antique siphash self test
  * haskell: re-add updated haskell example
  * socket: use ip_rt_put instead of dst_release
  * device: avoid double icmp send on routing loop
  * compat: clean up cruft
  * global: cleanup IP header checking
  * compat: do not export symbols unnecessarily
  
  Various cleanups and updates.
  
  * device: netdevice destruction logic change for 4.12
  
  When Linux 4.12 is released next week, we're good to go.
  
  * device: only use one sleep notifier
  
  Rather than have a separate sleep notification for every interface, we now
  have a single notifier for every interface. This improves performance,
  especially when creating many interfaces at once.
  
  * device: remove icmp conntrack hacks
  
  We're moving hacks upstream the proper way, and then backporting them to
  compat.
  
  * receive: extend rate limiting to 1 second after under load detection
  
  After we determine that we're under load, we now wait 1 second before not
  being under load again, a timer which is global across all interfaces on a
  given system.
  
  * curve25519: satisfy sparse and use short types
  * curve25519: keep certain sandy2x functions in C
  
  Certain functions have been made into C, which should improve stack frames and
  reliability.
  
  * ratelimiter: rewrite from scratch
  
  This is a big change. We no longer rely on x_tables or xt_hashlimit, instead
  using a super minimal and sleek token bucket ratelimiter. This works much
  better than the old cruft and should allow us to run more places. It also has
  the benefit of being global, so that it's possible to have thousands of
  interfaces without killing the system with separate GCs and vmallocs, which is
  what happened prior.
  
  * socket: verify saddr belongs to interface
  
  We now more quickly react to changes of the v4 routing table, by ensuring that
  the sticky source address is actually still valid.
  
  * wg-quick: properly match IPv6 endpoint
  
  wg-quick now works better with IPv6.
  
  * wg-quick: use printf -v instead of namerefs for bash 4.2
  
  This adds support for old bash, which means wg-quick should be generically
  "bash 4 and up". I'm not happy about this but EL7 uses old bash, so we're
  stuck with it.
  
  * compat: support EL7.3
  
  Support for RHEL, CentOS, ScientificLinux, and so forth.
  
  * compat: support Ubuntu 14.04
  
  An old crufty Ubuntu is now supported, since it's LTS.