This can happen if an IKE_SA is initiated to a static IP before DHCP is
done. Instead of failing the initiation, we either fake a NAT situation
(for IPv4) or disable NAT-D (for IPv6 where NATs and UDP-encap are not
widely used or supported).
This also removes the old fallbacks to determine the source address(es).
A source address lookup is done in ike_sa_t::resolve_hosts() (wasn't the
case initially) and enumerating local IPs (which was added even earlier)
could still lead to issues if e.g. LAN addresses are available but the
WAN address that's later used is not yet (in which case only the responder
would detect a NAT and UDP-encap would be configured asymmetrically).
To force UDP-encap locally in case there is no actual NAT, we store this
as COND_NAT_HERE instead of COND_NAT_FAKE. This ensures DPDs will contain
NAT-D notifies and we can later remove the state via MOBIKE. We trigger
a MOBIKE update after such a DPD by registering a changed NAT mapping after
checking for a disappearing local NAT, which is very unlikely to happen
outside of a MOBIKE update (where that flag is not checked).
Without this, the authentication succeeded if the server sent an early
EAP-Success message for mutual, key-generating EAP methods like EAP-TLS,
which may be used in EAP-only scenarios but would complete without server
or client authentication. For clients configured for such EAP-only
scenarios, a rogue server could capture traffic after the tunnel is
established or even access hosts behind the client. For non-mutual EAP
methods, public key server authentication has been enforced for a while.
A server previously could also crash a client by sending an EAP-Success
immediately without initiating an actual EAP method.
Fixes: 0706c39cda ("added support for EAP methods not establishing an MSK")
Fixes: CVE-2021-45079
This is useful for kernel implementations where the ordering of SAs
is unpredictable and the new SA might otherwise not be used until the
DELETE response has been received, which is not ideal as the responder
might not keep the old SA around that long. On Linux, it makes no
difference as we switch to the new outbound SA immediately because the
updated outbound policy references its SPI.
Currently the length of vendor ID Cisco VPN Concentrator is 16
bytes but the string has only 13+1 bytes. The actual vendor
ID has 16 bytes with a prefix length of 14 bytes and two version
bytes.
Fixes: 6c49ddfbca ("ike: Add additional Vendor IDs for third-party implementations")
If we initiated a make-before-break reauthentication and the peer
concurrently deletes the IKE_SA (e.g. because it uses break-before-make
reauthentication), we would create a duplicate IKE_SA (the condition forces
a recreation of all existing CHILD_SAs because reestablish() is also called
to complete a break-before-make reauthentication).
The addresses observed by the client behind the NAT are exactly the same if
the NAT router gets restarted.
Fixes: 2b255f01af ("ike-mobike: Use ike_sa_t::update_hosts() to trigger events")
This now includes all key material derived for IKE_SAs in the order
defined in the RFC:
{SK_d | SK_ai | SK_ar | SK_ei | SK_er | SK_pi | SK_pr}
= prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr)
Signed-off-by: Thomas Egerer <[email protected]>
For some that are followed by unknown data (e.g. detailed version
information) we only do a prefix match.
Co-authored-by: Tobias Brunner <[email protected]>
Closesstrongswan/strongswan#393.
If rekeying and reauthetication coincided, the reauth job could get
scheduled to run immediately i.e. before checkin() was called. So the
new IKE_SA would not get reauthenticated, however, the further delayed
delete job would later find the new IKE_SA and delete it.
We don't actually check that SA out (i.e. it's not registered with the
manager). That was originally different but had to be changed with
86993d6b90 to avoid that SAs created for rekeying don't block other
threads on the manager.
This allows more fine grained control over what's updated and does not
require multiple calls of the method. Plus we'll be able to use it in
the ike-mobike task.
If we are already deleting the old/redundant CHILD_SA, we must not
migrate the child-create task as that would destroy the new CHILD_SA we
already moved to the IKE_SA.
Fixes#3644.
The message_t object used for defragmentation was only cleared after
all fragments have been received and the message was delivered. So
if we received only some fragments of a retransmitted message, the
fragments of the next message were not processed (message_t returns
INVALID_ARG if the message ID does not match causing the message to
get ignored). This rendered the IKE_SA unusable as the client
obviously never retransmitted the fragments of that previous message
after it received our response.
We create the child_sa_t object when initiating the CREATE_CHILD_SA
request, however, the IP addresses/ports might have changed once we
eventually receive the response (potentially to a retransmit sent to
a different address). So update them before installing the SA and
policies.
If the local address changed too and depending on the kernel
implementation, the temporary SA created to allocate the inbound SPI
might remain as it can't be updated. This could cause issues if e.g.
the address switches back before that SA expired (the updated inbound
SA conflicts with the temporary one), or if that happens close together
and the expire (having to wait for the address update) causes the
updated SA to get deleted.
Fixes#3164.
A new global option enables sending this vendor ID to prevent Cisco
devices from narrowing the initiator's local traffic selector to the
requested virtual IP, so e.g. 0.0.0.0/0 can be used instead.
This has been tested with a "tunnel mode ipsec ipv4" Cisco template but
should also work for GRE encapsulation.
Closesstrongswan/strongswan#180.
If a MOBIKE task is deferred, the retransmission counter is reset to 0
when reinitiating. So if there were retransmits before, this alert would
not be triggered if a response is received now without retransmits.
Retransmission jobs for old requests for which we already received a
response previously left the impression that messages were sent more
recently than was actually the case.
task_manager_t always defined INVALID_STATE as possible return value if
no retransmit was sent, this just was never actually returned.
I guess we could further differentiate between actual invalid states
(e.g. if we already received the response) and when we don't send a
retransmit for other reasons e.g. because the IKE_SA became stale.
Due to the exponential backoff a high number of retransmits only
makes sense if retransmit_limit is set. However, even with that there
was a problem.
We first calculated the timeout for the next retransmit and only then
compared that to the configured limit. Depending on the configured
base and timeout the calculation overflowed the range of uint32_t after
a relatively low number of retransmits (with the default values after 23)
causing the timeout to first get lower (on a high level) before constantly
resulting in 0 (with the default settings after 60 retransmits).
Since that's obviously lower than any configured limit, all remaining
retransmits were then sent without any delay, causing a lot of concurrent
messages if the number of retransmits was high.
This change determines the maximum number of retransmits until an
overflow occurs based on the configuration and defaults to UINT32_MAX
if that value is exceeded. Note that since the timeout is in milliseconds
UINT32_MAX equals nearly 50 days.
The calculation in task_manager_total_retransmit_timeout() uses a double
variable and the result is in seconds so the maximum number would be higher
there (with the default settings 1205). However, we want its result to
be based on the actual IKE retransmission behavior.
Some peers apparently don't send the notify and still expect to
authenticate with EAP-only authentication. This option allows forcing
the configured use of EAP-only authentication in that scenario.
If such a task was active while reestablishing it will get queued on the
new IKE_SA. If the DH group is already set, the DH groups won't be
stripped from the proposals and a KE payload will be sent, which is invalid
during IKE_AUTH. We don't want to reset the group if the task is part of a
child-rekey task.
Charon refuses to make use of algorithms IDs from the private space
for unknown peer implementations [1]. If you chose to ignore and violate
that section of the RFC since you *know* your peers *must* support those
private IDs, there's no way to disable that behavior.
With this commit a strongswan.conf option is introduced which allows to
deliberately ignore parts of section 3.12 from the standard.
[1] http://tools.ietf.org/html/rfc7296#section-3.12
Signed-off-by: Thomas Egerer <[email protected]>
RFC 7296, section 2.21.3:
If a peer parsing a request notices that it is badly formatted (after
it has passed the message authentication code checks and window
checks) and it returns an INVALID_SYNTAX notification, then this
error notification is considered fatal in both peers, meaning that
the IKE SA is deleted without needing an explicit Delete payload.
RFC 7296, section 2.21.3:
If a peer parsing a request notices that it is badly formatted (after
it has passed the message authentication code checks and window
checks) and it returns an INVALID_SYNTAX notification, then this
error notification is considered fatal in both peers, meaning that
the IKE SA is deleted without needing an explicit Delete payload.
This avoids having to register certificates with authority/ca backends
beforehand, which is tricky for intermediate CA certificates loaded
themselves via authority/ca sections. On the other hand, the form of
these URLs can't be determined by config backends anymore (not an issue
for the two current implementations, no idea if custom implementations
ever made use of that possibility). If that became necessary, we could
perhaps pass the certificate to the CDP enumerator or add a new method
to the credential_set_t interface.
This avoids having to call strip_dh() in child_cfg_t::get_proposals().
It also inverts the ALLOW_PRIVATE flag (i.e. makes it SKIP_PRIVATE) so
nothing has to be supplied to clone complete proposals.
During proposal selection with ike/child_cfgs a couple of boolean
variables can be set (e.g. private, prefer_self, strip_dh). To simplify
the addition of new parameters, these functions now use a set of flags
instead of indiviual boolean values.
Signed-off-by: Thomas Egerer <[email protected]>
There seem to be servers around that, upon receiving a delete from the
client, instead of responding with an empty INFORMATIONAL, send a delete
themselves.
Previously, the initiator would install the SA in transport mode if the
peer sent back the USE_TRANSPORT_MODE notify, even if that was not
requested originally.
Previously, attributes in an incorrectly sent CFG_REPLY would still be passed
to attribute handlers. This does not prevent handlers from receiving
unrequested attributes if they requested at least one other.
Tobias Brunner