This change performs the algorithm rejection in the corresponding NAS
handler for 5G, since the protocol definitions differ between LTE and
5G, regarding NIA0/EIA0 user plane traffic.
Therefore, for 5G NIA0 is rejected, since it is not allowed under normal
circumstances, while LTE user plane traffic can indeed have EIA0
selected.
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
It is not allowed to accept an unauthenticated SMC message,
as this effectively bypasses all security measures and
enables a malicioius attacker to compromise the confidentiality
and integrity of exchanged messages.
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
Co-authored-by: Guido Casati <hello@guidocasati.com>
Retrieving the mac is necessary during the handling of the SMC, since the
context is generated from the specified keys therein. Therefore, it is
necessary to check the MAC right after generation and ensure the authenticity
of the message. If it is not given, the message must be rejected.
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
Co-authored-by: Guido Casati <hello@guidocasati.com>
This is necessary to indicate to the Core network, that
the security mode command procedure has failed.
Check for the security context presence when generating the Security Mode
reject message: according to 3GPP TS 24.501 5.4.2.5 "NAS security mode command
not accepted by the UE" The UE shall send a SECURITY MODE REJECT containing
a 5GMM cause that typically indicates one of the following cause values:
(23) UE security capabilities mismatch
(24) security mode rejected, unspecified
The message shall be protected if a security context is available
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
Co-authored-by: Guido Casati <hello@guidocasati.com>
This change adds lengths checks to the received registration reject
message and also performs a bounds check for the received cause.
Since the cause is not checked, any string in the memory can be
dereferenced, possibly leading to DoS.
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
The change addresses the SM message type retrieval for DL NAS Transport
messages. The assumption of an offset 17 = 7 (MM Sec) + 3 (MM Plain) + 1
(IEI) + 2 (Len) + 4 (SM) is correct.
However, if the DL NAS Transport is received in a plain header, the
lengths would not add up anymore. (This is not complying with the
standard, so not allowed, but possible). The check for the length is
necessary to not process arbitrary memory contents beyond the
`pdu_buffer`.
Signed-off-by: Eduard Vlad <eduard.vlad@rwth-aachen.de>
Eduard Vlad