As we set the remote port to 0, we'd get a mapping change message with
every packet. Setting the threshold avoids all kernel messages after the
first, which we suppress explicitly as well.
This might make debugging easier and also ensures that a possible
fallback SA without CPU ID is established first when reestablishing
an IKE_SA. Because even if such an SA is established first initially,
that might change later depending on when per-CPU SAs are rekeyed.
Not sure if this combination does make sense as the plugin itself would
be a major bottleneck.
Similar to the connmark plugin, PREROUTING rules list SPIs or UDP ports,
which would be necessary for all SAs while the OUTPUT rules would only be
required once.
The combination probably doesn't make much sense.
The OUTPUT rules would definitely only be required once, while the INPUT
and PREROUTING rules list individual SPIs and/or UDP ports, which would
be necessary for all SAs.
By the way, the rules in PREROUTING might actually not be necessary
anymore if the set_mark_in option was used for such SAs.
This uses the sequence number from acquires when installing the SA. This
allows handling narrowing properly by changing the reqid and still
removing the temporary state in the kernel. It also changes that
traffic selectors are reused during rekeying/recreation/reauthentication,
so narrowed selectors won't return to the wider configured TS because
there won't be any TS from triggering packets to narrow again.
Besides the previous key exchange method, this will allow us to also
reuse the previous traffic selectors. Some data is still passed in
separate methods as some are set even when there is no previous SA and
others are not set in all cases.
The interface for queue_child() now optionally takes the previous
Child SA to handle both recreations and initiations from scratch.
This fixes cases where `start_action = trap|start` is used and an acquire
is triggered while the SA is initiated (granted if narrowing is expected,
that's not a recommended configuration as the responder can only use
the first config when there is no packet TS). The resulting second
create-child task will potentially get dropped by the duplicate check,
so the temporary state won't get removed and traffic is blocked until
that expires, neither can acquires get triggered for traffic that doesn't
match the initial SA's policies.
This was the case before bce0c5fd74a0 ("child-create: Update CHILD_SA IP
addresses before installation") and allows listeners to consider the
traffic selectors of the SA that's about to get installed.
The addresses are actually the endpoints of the SA, not information on
the matched packet (except that the RFC says to set the ports and
protocol of the packet in the source address, which the Linux kernel
doesn't do). So these are useless, unless transport mode is used, where
the addresses are needed for the wildcard trap policy use case.
The RFC mentions a PROXY address (a single one, not two), that could
apparently be something like the source address in tunnel mode.
However, the description of how this is used in the RFC is quite weird
and neither Linux nor FreeBSD send such an attribute in SADB_ACQUIRE.
Note that while PF_KEYv2 also uses sequence numbers to identify acquires,
which we currently don't use correctly by the way, it does not include
information about the packet that triggered an acquire. What we receive
in src and dst, and currently forward as traffic selectors, are actually
the designated endpoints of the SA. So especially in tunnel mode this is
useless to do narrowing on the responder (these addresses might not even
match the configured TS).
With the sequence numbers we don't have to maintain the reqid to delete
the temporary state.
One exception is with labels. There we currently only install trap
policies with the generic label. SAs created from those don't have
policies installed, so we have to reuse the reqid of the trap even if
narrowing occurs.
And as before, we reuse the reqid without checking traffic selectors if
sequence numbers are not supported.
Note that if a CHILD_SA is manually initiated (i.e. has no sequence
number assigned) right before an acquire is triggered, there are several
possible outcomes depending on whether narrowing occurs. If there is no
narrowing, the same reqid is assigned and the kernel will remove the
temporary SA when the SA is installed (no seq => reqid match).
Afterwards, the queued duplicate CHILD_SA is destroyed and the acquire
state in the trap manager gets removed. If there is narrowing, a new
reqid is allocated, so the installation of the SA will not remove the
temporary state. However, due to the narrowing, the duplicate check
fails and when the duplicate is installed (with sequence number), the
temporary state is deleted (as is the state in the trap manager).
Optionally with "dynamic" traffic selectors resolved. A new method
is added for those cases where we actually want to select potentially
narrowed traffic selectors using a supplied list. The latter now also
always logs details, while the former does not.
