From: Harald Freudenberger freude@linux.ibm.com
commit af40322e90d4e0093569eceb7d3a28ab635f3e75 upstream.
All kind of administrative requests should not been retried. Some card firmware detects this and assumes a replay attack. This patch checks on failure if the low level functions indicate a retry (EAGAIN) and checks for the ADMIN flag set on the request message. If this both are true, the response code for this message is changed to EIO to make sure the zcrypt API layer does not attempt to retry the request. As of now the ADMIN flag is set for a request message when - for EP11 the field 'flags' of the EP11 CPRB struct has the leftmost bit set. - for CCA when the CPRB minor version is 'T3', 'T5', 'T6' or 'T7'.
Please note that the do-not-retry only applies to a request which has been sent to the card (= has been successfully enqueued) but the reply indicates some kind of failure and by default it would be replied. It is totally fine to retry a request if a previous attempt to enqueue the msg into the firmware queue had some kind of failure and thus the card has never seen this request.
Reported-by: Frank Uhlig Frank.Uhlig1@ibm.com Signed-off-by: Harald Freudenberger freude@linux.ibm.com Reviewed-by: Holger Dengler dengler@linux.ibm.com Cc: stable@vger.kernel.org Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/crypto/zcrypt_msgtype6.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/s390/crypto/zcrypt_msgtype6.c +++ b/drivers/s390/crypto/zcrypt_msgtype6.c @@ -1188,6 +1188,9 @@ static long zcrypt_msgtype6_send_cprb(bo ap_cancel_message(zq->queue, ap_msg); }
+ if (rc == -EAGAIN && ap_msg->flags & AP_MSG_FLAG_ADMIN) + rc = -EIO; /* do not retry administrative requests */ + out: if (rc) ZCRYPT_DBF_DBG("%s send cprb at dev=%02x.%04x rc=%d\n", @@ -1308,6 +1311,9 @@ static long zcrypt_msgtype6_send_ep11_cp ap_cancel_message(zq->queue, ap_msg); }
+ if (rc == -EAGAIN && ap_msg->flags & AP_MSG_FLAG_ADMIN) + rc = -EIO; /* do not retry administrative requests */ + out: if (rc) ZCRYPT_DBF_DBG("%s send cprb at dev=%02x.%04x rc=%d\n",