David Anderson 358cd3fd92 ipn: fix incorrect change tracking for packet filter.
ORder of operations to trigger a problem:
 - Start an already authed tailscaled, verify you can ping stuff.
 - Run `tailscale up`. Notice you can no longer ping stuff.

The problem is that `tailscale up` stops the IPN state machine before
restarting it, which zeros out the packet filter but _not_ the packet
filter hash. Then, upon restarting IPN, the uncleared hash incorrectly
makes the code conclude that the filter doesn't need updating, and so
we stay with a zero filter (reject everything) for ever.

The fix is simply to update the filterHash correctly in all cases,
so that running -> stopped -> running correctly changes the filter
at every transition.

Signed-off-by: David Anderson <danderson@tailscale.com>
2020-07-31 19:12:45 -07:00
..