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iscsi-target: Reject mutual authentication with reflected CHAP_C

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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>
This commit is contained in:
Nicholas Bellinger 2014-06-05 18:08:57 -07:00
parent 5256ffdbdc
commit 1d2b60a554
1 changed files with 10 additions and 0 deletions
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10
drivers/target/iscsi/iscsi_target_auth.c
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@ -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.
*/