Hi Tejas,
On Thu, 2014-06-05 at 15:40 +0530, Tejas Vaykole wrote:
> Hi,
> The iSCSI target is expected to send a Login reject when it receives the
> CHAP_C value which target or initiator
> has used in previous attempts for authentication (as stated in RFC
> 1994,section 4.1). However ,
> i find that LIO is accepting the reuse of CHAP_C values,and sends a
> Login success which is an error.
> RFC 1994 section 4.1
> -------------<snip>--------------
> The Challenge Value MUST be changed each time a Challenge is sent.
> Originators MUST NOT reuse the CHAP
> challenge sent by the Responder for the other direction of a
> bidirectional authentication. Responders MUST
> check for this condition and close the iSCSI TCP connection if it occurs.
> -------------<snip>--------------
>
> i have attached the pcap for the same.
>
Thanks for reporting. I'm applying the following patch to address this
case. Please test + confirm.
Thank you,
--nab
>From 57e9e7d1084bb8a364ef9d91d9531cd987ff9048 Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Thu, 5 Jun 2014 18:08:57 -0700
Subject: [PATCH 19/19] iscsi-target: Reject mutual authentication with
reflected CHAP_C
This patch adds an explicit check in chap_server_compute_md5() to ensure
the CHAP_C value received from the initiator during mutual authentication
does not match the original CHAP_C provided by the target.
This is in line with RFC-3720, section 8.2.1:
Originators MUST NOT reuse the CHAP challenge sent by the Responder
for the other direction of a bidirectional authentication.
Responders MUST check for this condition and close the iSCSI TCP
connection if it occurs.
Reported-by: Tejas Vaykole <tejas.vaykole@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 3.1+
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/iscsi/iscsi_target_auth.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/target/iscsi/iscsi_target_auth.c b/drivers/target/iscsi/iscsi_target_auth.c
index ec00042..635fc5e 100644
--- a/drivers/target/iscsi/iscsi_target_auth.c
+++ b/drivers/target/iscsi/iscsi_target_auth.c
@@ -344,6 +344,16 @@ static int chap_server_compute_md5(
goto out;
}
/*
+ * During mutual authentication, the CHAP_C generated by the
+ * initiator must not match the original CHAP_C generated by
+ * the target.
+ */
+ if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
+ pr_err("initiator CHAP_C matches target CHAP_C, failing"
+ " login attempt\n");
+ goto out;
+ }
+ /*
* Generate CHAP_N and CHAP_R for mutual authentication.
*/
tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
--
1.7.10.4
--
To unsubscribe from this list: send the line "unsubscribe target-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
