Commit 1d2b60a5 authored Jun 05, 2014 by Nicholas Bellinger

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@calsoftinc.com>
Cc: stable@vger.kernel.org # 3.1+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

parent 5256ffdb

drivers/target/iscsi/iscsi_target_auth.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -351,6 +351,16 @@ static int chap_server_compute_md5(
		pr_err("Unable to convert incoming challenge\n");
		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.
		*/