an issue with macsec key agreement (machine falling out of sync?)
Moritz Wilhelmy
mw-hostap at barfooze.de
Fri Feb 23 06:30:56 PST 2024
Hi Jaap,
Our plan was to have about at least 32-64 machines on the same ethernet.
Thanks for the explanation and clarifying that I'm not imagining things
though! :)
Best regards,
Moritz
On Thu, Feb 22, 2024 at 08:15:56PM +0100, Jaap Keuter wrote:
> Hi,
>
> Yes, I’ve seen that too. Recently it seemed to have gotten better, but the issue is still there.
> Although I’ve been searching for it, I’ve only come across a single observation which lead to an idea for a change.
>
> --------------------------- src/pae/ieee802_1x_kay.c ---------------------------
> index b0a418ef0..442d487f7 100644
> @@ -1101,9 +1101,11 @@ ieee802_1x_mka_i_in_peerlist(struct ieee802_1x_mka_participant *participant,
> * values (i.e., peer having copied my MI,MN
> * from either of the last two MKPDUs that I
> * have sent). */
> - if (mn == participant->mn ||
> - (participant->mn > 1 &&
> - mn == participant->mn - 1))
> + /* BUG: This is shown to be too tight.
> + * With packets being send/received out of
> + * sequence this assumption is not valid.
> + * Adjusted to three. */
> + if (participant->mn + 3 >= mn)
> return true;
> }
> }
>
>
> I’ve created a test setup which allows you to experiment with this on a single linux host.
> https://gitlab.com/JaapKeuter/MACsec-sim
> Now it works fairly well with three nodes, but increasing to eight, for instance, shows the failure.
>
> Hope it helps.
>
>
> > On 21 Feb 2024, at 17:34, Moritz Wilhelmy <mw-hostap at barfooze.de> wrote:
> >
> > Hello,
> >
> > Before I will probably have to bury this macsec project at work I want
> > to report what appears to be a bug to me in wpa_supplicant's macsec key
> > agreement (MKA) implementation:
> >
> > I have 3 machines: ed0, ed1 and ed2, they all share the same
> > wpa_supplicant.conf with the same values for MKA pre-shared keys and
> > systemd unit that starts wpa_supplicant.
> >
> > Sometimes when I reboot all machines it works fine on start up, when I
> > ping the IPv6 link local multicast address ff02::1%macsec0 I get
> > response packets from all three machines:
> >
> > ed0# ping ff02::1%macsec0
> > PING ff02::1%macsec0(ff02::1%macsec0) 56 data bytes
> > 64 bytes from fe80::4801:e9ff:fe34:a268%macsec0: icmp_seq=1 ttl=64 time=0.117 ms
> > 64 bytes from fe80::747f:28ff:fedc:abaa%macsec0: icmp_seq=1 ttl=64 time=2.85 ms (DUP!)
> > 64 bytes from fe80::60a2:b8ff:fe98:ad8f%macsec0: icmp_seq=1 ttl=64 time=4.67 ms (DUP!)
> > ^C
> >
> > Other times one of the machines seems to have issues with key agreement
> > despite having the same shared key as the other machines (i.e. only one
> > DUP! response on pinging the multicast address):
> >
> > $ ssh ed1
> > Warning: Permanently added 'fe80::4801:e9ff:fe34:a268%eno1' (ED25519) to the list of known hosts.
> > ed1# ping ff02::1%macsec0
> > PING ff02::1%macsec0(ff02::1%macsec0) 56 data bytes
> > 64 bytes from fe80::4801:e9ff:fe34:a268%macsec0: icmp_seq=1 ttl=64 time=0.112 ms
> > 64 bytes from fe80::60a2:b8ff:fe98:ad8f%macsec0: icmp_seq=1 ttl=64 time=4.89 ms (DUP!) <--- second DUP! from the 3rd machine is missing
> > 64 bytes from fe80::4801:e9ff:fe34:a268%macsec0: icmp_seq=2 ttl=64 time=0.098 ms
> > 64 bytes from fe80::60a2:b8ff:fe98:ad8f%macsec0: icmp_seq=2 ttl=64 time=2.69 ms (DUP!)
> > ^C
> > --- ff02::1%macsec0 ping statistics ---
> > 2 packets transmitted, 2 received, +2 duplicates, 0% packet loss, time 1001ms
> > rtt min/avg/max/mdev = 0.098/1.947/4.890/1.999 ms
> > ed1# systemctl status wpa_supplicant
> > ● wpa_supplicant.service - WPA supplicant
> > Loaded: loaded (/lib/systemd/system/wpa_supplicant.service; enabled; vendor preset: disabled)
> > Active: active (running) since Sat 2024-02-10 16:07:19 UTC; 20s ago
> > Main PID: 496 (wpa_supplicant)
> > Tasks: 1 (limit: 404)
> > Memory: 4.9M
> > CGroup: /system.slice/wpa_supplicant.service
> > └─496 /usr/sbin/wpa_supplicant -u -i br0 -Dmacsec_linux -c /etc/wpa_supplicant.conf
> >
> > Feb 10 16:07:19 hostname systemd[1]: Starting WPA supplicant...
> > Feb 10 16:07:19 hostname wpa_supplicant[496]: Successfully initialized wpa_supplicant
> > Feb 10 16:07:19 hostname systemd[1]: Started WPA supplicant.
> > Feb 10 16:07:20 hostname wpa_supplicant[496]: br0: Associated with 01:80:c2:00:00:03
> > Feb 10 16:07:20 hostname wpa_supplicant[496]: br0: CTRL-EVENT-CONNECTED - Connection to 01:80:c2:00:00:03 completed [id=0 id_str=]
> > Feb 10 16:07:20 hostname wpa_supplicant[496]: br0: CTRL-EVENT-SUBNET-STATUS-UPDATE status=0
> > Feb 10 16:07:26 hostname wpa_supplicant[496]: KaY: duplicated SCI detected - maybe active attacker or peer selected new MI - ignore MKPDU
> > Feb 10 16:07:28 hostname wpa_supplicant[496]: KaY: duplicated SCI detected - maybe active attacker or peer selected new MI - ignore MKPDU
> > Feb 10 16:07:30 hostname wpa_supplicant[496]: KaY: duplicated SCI detected - maybe active attacker or peer selected new MI - ignore MKPDU
> > Feb 10 16:07:33 hostname wpa_supplicant[496]: KaY: Life time has not elapsed since prior SAK distributed
> > ed1# logout
> > Connection to fe80::4801:e9ff:fe34:a268%eno1 closed.
> >
> > $ ssh ed2
> > Warning: Permanently added 'fe80::60a2:b8ff:fe98:ad8f%eno1' (ED25519) to the list of known hosts.
> > ed2# systemctl status wpa_supplicant
> > ● wpa_supplicant.service - WPA supplicant
> > Loaded: loaded (/lib/systemd/system/wpa_supplicant.service; enabled; vendor preset: disabled)
> > Active: active (running) since Sat 2024-02-10 16:01:48 UTC; 47s ago
> > Main PID: 496 (wpa_supplicant)
> > Tasks: 1 (limit: 404)
> > Memory: 4.8M
> > CGroup: /system.slice/wpa_supplicant.service
> > └─496 /usr/sbin/wpa_supplicant -u -i br0 -Dmacsec_linux -c /etc/wpa_supplicant.conf
> >
> > Feb 10 16:01:47 hostname systemd[1]: Starting WPA supplicant...
> > Feb 10 16:01:48 hostname wpa_supplicant[496]: Successfully initialized wpa_supplicant
> > Feb 10 16:01:48 hostname systemd[1]: Started WPA supplicant.
> > Feb 10 16:01:48 hostname wpa_supplicant[496]: br0: Associated with 01:80:c2:00:00:03
> > Feb 10 16:01:48 hostname wpa_supplicant[496]: br0: CTRL-EVENT-CONNECTED - Connection to 01:80:c2:00:00:03 completed [id=0 id_str=]
> > Feb 10 16:01:48 hostname wpa_supplicant[496]: br0: CTRL-EVENT-SUBNET-STATUS-UPDATE status=0
> > Feb 10 16:01:54 hostname wpa_supplicant[496]: KaY: duplicated SCI detected - maybe active attacker or peer selected new MI - ignore MKPDU
> > Feb 10 16:01:56 hostname wpa_supplicant[496]: KaY: duplicated SCI detected - maybe active attacker or peer selected new MI - ignore MKPDU
> > ed2# logout
> > Connection to fe80::60a2:b8ff:fe98:ad8f%eno1 closed.
> >
> > $ ssh ed0
> > Warning: Permanently added 'fe80::747f:28ff:fedc:abaa%eno1' (ED25519) to the list of known hosts.
> > ed0# systemctl status wpa_supplicant
> > ● wpa_supplicant.service - WPA supplicant
> > Loaded: loaded (/lib/systemd/system/wpa_supplicant.service; enabled; vendor preset: disabled)
> > Active: active (running) since Sat 2024-02-10 16:07:00 UTC; 54s ago
> > Main PID: 495 (wpa_supplicant)
> > Tasks: 1 (limit: 404)
> > Memory: 4.8M
> > CGroup: /system.slice/wpa_supplicant.service
> > └─495 /usr/sbin/wpa_supplicant -u -i br0 -Dmacsec_linux -c /etc/wpa_supplicant.conf
> >
> > Feb 10 16:07:06 hostname wpa_supplicant[495]: KaY: The peer (73cec9c3a974289e25a335a4) is not my live peer - ignore MACsec SAK Use param>
> > Feb 10 16:07:06 hostname wpa_supplicant[495]: KaY: Discarding Rx MKPDU: decode of parameter set type (3) failed
> > Feb 10 16:07:06 hostname wpa_supplicant[495]: KaY: The peer (73cec9c3a974289e25a335a4) is not my live peer - ignore MACsec SAK Use param>
> > Feb 10 16:07:06 hostname wpa_supplicant[495]: KaY: Discarding Rx MKPDU: decode of parameter set type (3) failed
> > Feb 10 16:07:07 hostname wpa_supplicant[495]: KaY: The peer (73cec9c3a974289e25a335a4) is not my live peer - ignore MACsec SAK Use param>
> > Feb 10 16:07:07 hostname wpa_supplicant[495]: KaY: Discarding Rx MKPDU: decode of parameter set type (3) failed
> > Feb 10 16:07:09 hostname wpa_supplicant[495]: KaY: The peer (73cec9c3a974289e25a335a4) is not my live peer - ignore MACsec SAK Use param>
> > Feb 10 16:07:09 hostname wpa_supplicant[495]: KaY: Discarding Rx MKPDU: decode of parameter set type (3) failed
> > Feb 10 16:07:11 hostname wpa_supplicant[495]: KaY: The peer (73cec9c3a974289e25a335a4) is not my live peer - ignore MACsec SAK Use param>
> > Feb 10 16:07:11 hostname wpa_supplicant[495]: KaY: Discarding Rx MKPDU: decode of parameter set type (3) failed
> >
> > ^^^^ seems to me that the culprit in this case is ed0 that somehow fell
> > out of sync with the others if I'm reading this right, but I didn't
> > write this software so perhaps you tell me :)
> >
> > Are you aware of/have you encountered this issue before? Is there any
> > known solution/software version where it's fixed?
> >
> > Here's some more context and diagnostical info:
> >
> > ed0# wpa_supplicant -v
> > wpa_supplicant v2.10
> > Copyright (c) 2003-2022, Jouni Malinen <j at w1.fi> and contributors
> >
> > ed0# uname -a
> > Linux hostname 5.4.24 #1 SMP PREEMPT Thu Oct 7 08:39:19 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
> >
> > ed0# cat /sys/class/net/br0/bridge/group_fwd_mask
> > 0x8
> >
> > ed0# cat /etc/wpa_supplicant.conf
> > ctrl_interface=/var/run/wpa_supplicant
> > eapol_version=3
> > ap_scan=0
> > fast_reauth=1
> >
> > network={
> > key_mgmt=NONE
> > eapol_flags=0
> > macsec_policy=1
> >
> > mka_cak=35659df249c7c90fcaeb675ef59eb783
> > mka_ckn=83f447da8078c18a7bae35851a0349384e9da84ab45a705f304731f3dc7fee
> > }
> >
> >
> >
> > The file is left as copied from the [RedHat introduction][1] with some
> > keys filled in where they belong and then copied identically to all
> > three machines.
> >
> > Sorry I had to edit the logs to remove the hostname, I've signed an NDA.
> >
> > Best regards,
> >
> > Moritz
> >
> > [1]: https://developers.redhat.com/blog/2017/06/28/whats-new-in-macsec-setting-up-macsec-using-wpa_supplicant-and-optionally-networkmanager#
> >
> > _______________________________________________
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> > http://lists.infradead.org/mailman/listinfo/hostap
>
>
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