Moving to the new SA only after receiving the DELETE for the old SA was
not ideal as it rendered the new SA unusable (because it simply didn't
exist in the manager) if the DELETE was delayed/got dropped.
This happens if the peer deletes the redundant SA before we are able to
handle the response. The deleted SA will be in state CHILD_INSTALLED but
we don't want to trigger the child_updown() event for it or recreate it.
Generally, we will not find the CHILD_SA by searching for it with the
outbound SPI (the initiator of the DELETE sent its inbound SPI) - and if
we found a CHILD_SA it would most likely be the wrong one (one in which
we used the same inbound SPI as the peer used for the one it deletes).
And we don't actually want to destroy the CHILD_SA at this point as we
know we already initiated a DELETE ourselves, which means that task
still has a reference to it and will destroy the CHILD_SA when it
receives the response from the other peer.
If two CHILD_SAs with mark=%unique are created concurrently they could
otherwise end up with either the same mark or different marks in both
directions.
This is the case for the IKE_SA_INIT and the initial IKEv1 messages, which
are pre-generated in tasks as at least parts of it are used to generate
the AUTH payload. The IKE_SA_INIT message will never be fragmented, but
the IKEv1 messages might be, so we can't just call generate_message().
Fixes#1478.
Some peers send an INITIAL_CONTACT notify after they received our XAuth
username. The XAuth task waiting for the third XAuth message handles
this incorrectly and closes the IKE_SA as no configuration payloads are
contained in the message. We queue the INFORMATIONAL until the XAuth
exchange is complete to avoid this issue.
Fixes#1434.
This provides a fix if symmetrically overlapping policies are
installed as e.g. the case in the ikev2/ip-two-pools-db scenario:
carol 10.3.0.1/32 ----- 10.3.0.0/16, 10.4.0.0/16 moon
alice 10.4.0.1/32 ----- 10.3.0.0/16, 10.4.0.0/16 moon
Among others, the following FWD policies are installed on moon:
src 10.3.0.1/32 dst 10.4.0.0/16
...
tmpl ...
src 10.4.0.0/16 dst 10.3.0.1/32
...
src 10.4.0.1/32 dst 10.3.0.0/16
...
tmpl ...
src 10.3.0.0/16 dst 10.4.0.1/32
...
Because the network prefixes are the same for all of these they all have the
same priority. Due to that it depends on the install order which policy gets
used. For instance, a packet from 10.3.0.1 to 10.4.0.1 will match the
first as well as the last policy. However, when handling the inbound
packet we have to use the first one as the packet will otherwise be
dropped due to a template mismatch. And we can't install templates with
the "outbound" FWD policies as that would prevent using different
IPsec modes or e.g. IPComp on only one of multiple SAs.
Instead we install the "outbound" FWD policies with a lower priority
than the "inbound" FWD policies so the latter are preferred. But we use
a higher priority than default drop policies would use (in case they'd
be defined with the same subnets).
If there is currently no route to reach the other peer we just default
to left=%any. The local address is only really used to resolve
leftsubnet=%dynamic anyway (and perhaps for MIPv6 proxy transport mode).
Fixes#1375.
An old (already rekeyed) CHILD_SA would get switched back into CHILD_REKEYING
state. And we actually want to change the currently installed CHILD_SA to
that state and later CHILD_REKEYED and properly call e.g. child_rekey() and
not do this again with an old CHILD_SA. Instead let's only check installed
or currently rekeying CHILD_SAs (in case of a rekey collision). It's also
uncommon that there is a CHILD_SA in state CHILD_REKEYED but none in state
CHILD_INSTALLED or CHILD_REKEYING, which could happen if e.g. a peer deleted
and recreated a CHILD_SA after a rekeying. But in that case we don't want
to treat the new CHILD_SA as rekeying (e.g. in regards to events on the bus).
If there is a DROP shunt that matches outbound forwarded traffic it
would get dropped as the FWD policy we install only matches decrypted
inbound traffic. That's because the Linux kernel first checks the FWD
policies before looking up the OUT policy and SA to encrypt the packets.
A thread might check out a new IKE_SA via checkout_new() or
checkout_by_config() and start initiating it while the daemon is
terminating and the IKE_SA manager is flushed by the main thread.
That SA is not tracked yet so the main thread is not waiting for it and
the other thread is able to check it in and creating an entry after flush()
already terminated causing a memory leak.
Fixes#1348.
We do these checks after the SA is fully established.
When establishing an SA the responder is always able to install the
CHILD_SA created with the IKE_SA before the initiator can do so.
During make-before-break reauthentication this could cause traffic sent
by the responder to get dropped if the installation of the SA on the
initiator is delayed e.g. by OCSP/CRL checks.
In particular, if the OCSP/CRL URIs are reachable via IPsec tunnel (e.g.
with rightsubnet=0.0.0.0/0) the initiator is unable to reach them during
make-before-break reauthentication as it wouldn't be able to decrypt the
response that the responder sends using the new CHILD_SA.
By delaying the revocation checks until the make-before-break
reauthentication is completed we avoid the problems described above.
Since this only affects reauthentication, not the original IKE_SA, and the
delay until the checks are performed is usually not that long this
doesn't impose much of a reduction in the overall security.
On failure the SA is deleted and reestablished as configured. The task
is activated after the REAUTH_COMPLETE task so a make-before-break reauth
is completed before the new SA might get torn down.
This allows for different signature schemes for IKE authentication and
trustchain verification.
Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
An attacker could blindly send a message with invalid nonce data (or none
at all) to DoS an initiator if we just destroy the SA. To prevent this we
ignore the message and wait for the one by the correct responder.
Tobias Brunner