DGNum/hostapd
6
0
Fork 0
Code Issues Pull requests 1 Projects Releases Packages Wiki Activity Actions

mka: Fix lowest acceptable Packet Number (LPN) calculation and use

Browse source 
The purpose of the Lowest Acceptable PN (lpn) parameters in the MACsec
SAK Use parameter set is to enforce delay protection. Per IEEE Std
802.1X-2010, Clause 9, "Each SecY uses MKA to communicate the lowest PN
used for transmission with the SAK within the last two seconds, allowing
receivers to bound transmission delays."

When encoding the SAK Use parameter set the KaY should set llpn and olpn
to the lowest PN transmitted by the latest SAK and oldest SAK (if
active) within the last two seconds. Because MKPDUs are transmitted
every 2 seconds (MKA_HELLO_TIME), the solution implemented here
calculates lpn based on the txsc->next_pn read during the previous MKPDU
transmit.

Upon receiving and decoding a SAK Use parameter set with delay
protection enabled, the KaY will update the SecY's lpn if the delay
protect lpn is greater than the SecY's current lpn (which is a product
of last PN received and replay protection and window size).

Signed-off-by: Michael Siedzik <msiedzik@extremenetworks.com>
This commit is contained in:
Mike Siedzik 2018-02-20 14:28:39 -05:00 • committed by Jouni Malinen
parent d9a0a72229
commit 2fc0675683
8 changed files with 144 additions and 27 deletions
Download patch file Download diff file Expand all files Collapse all files

1
src/pae/ieee802_1x_kay.h
View file

@ -150,6 +150,7 @@ struct ieee802_1x_kay_ctx {
int (*get_receive_lowest_pn)(void *ctx, struct receive_sa *sa);
int (*get_transmit_next_pn)(void *ctx, struct transmit_sa *sa);
int (*set_transmit_next_pn)(void *ctx, struct transmit_sa *sa);
int (*set_receive_lowest_pn)(void *ctx, struct receive_sa *sa);
int (*create_receive_sc)(void *ctx, struct receive_sc *sc,
enum validate_frames vf,
enum confidentiality_offset co);