From 1d2b60a5545942b1376cb48c1d55843d71e3a08f Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Thu, 5 Jun 2014 18:08:57 -0700 Subject: [PATCH] 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 Cc: stable@vger.kernel.org # 3.1+ Signed-off-by: Nicholas Bellinger --- 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 155f33848aa6..19b842c3e0b3 100644 --- a/drivers/target/iscsi/iscsi_target_auth.c +++ b/drivers/target/iscsi/iscsi_target_auth.c @@ -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. */