The previous code had some issues because it handled each child config
separately. Not only was this quite inefficient because all IKE_SAs had
to be enumerated for every config, it also caused problems with the check
for other CHILD_SAs in order to decide whether to delete the IKE_SA or
not. Because CHILD_SAs are deleted with an INFORMATIONAL exchange, they
are not immediately gone. This caused a race condition and with more
than one child config and SAs the IKE_SA could be kept because it
could appear as if other, unrelated CHILD_SAs were still there.
Another race condition, which is fixed by the previous commit, occurred
when only changing child configs. Then it could happen that the code
deemed the IKE_SA empty and a delete for it was queued. If that happened
while the IKE_SA was deleting one of the CHILD_SAs (or was busy with some
other exchange), the IKE_SA was not switched to IKE_DELETING. So it
looked usable and create-child tasks for the updated configs might have
gotten queued. Unfortunately, once the ike-delete task is eventually
executed, these tasks would be gone and the replacement CHILD_SAs never
created. This commit additionally avoids actually deleting the IKE_SA
even if all child configs change or get removed if any new CHILD_SAs are
to be initiated.
Tobias Brunner
7bfaa9acb6