[SCSI] iscsi_tcp: fix padding, data digests, and IO at weird offsets

iscsi_tcp calculates padding by using the expected transfer length. This
has the problem where if we have immediate data = no and initial R2T =
yes, and the transfer length ended up needing padding then we send:

1. header
2. padding which should have gone after data
3. data

Besides this bug, we also assume the target will always ask for nice
transfer lengths and the first burst length will always be a nice value.
As far as I can tell form the RFC this is not a requirement. It would be
silly to do this, but if someone did it we will end doing bad things.

Finally the last bug in that bit of code is in our handling of the
recalculation of data digests when we do not send a whole iscsi_buf in
one try. The bug here is that we call crypto_digest_final on a
iscsi_sendpage error, then when we send the rest of the iscsi_buf, we
doiscsi_data_digest_init and this causes the previous data digest to be
lost.

And to make matters worse, some of these bugs are replicated over and
over and over again for immediate data, solicited data and unsolicited
data. So the attached patch made over the iscsi git tree (see
kernel.org/git for details) which I updated today to include the patches
I said I merged, consolidates the sending of data, padding and digests
and calculation of data digests and fixes the above bugs.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 31 insertions, 6 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 9584cbc082f..fb65311c81d 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -325,6 +325,30 @@ static void iscsi_tmf_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 	wake_up(&conn->ehwait);
 }
 
+static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+			       char *data, int datalen)
+{
+	struct iscsi_reject *reject = (struct iscsi_reject *)hdr;
+	struct iscsi_hdr rejected_pdu;
+	uint32_t itt;
+
+	conn->exp_statsn = be32_to_cpu(reject->statsn) + 1;
+
+	if (reject->reason == ISCSI_REASON_DATA_DIGEST_ERROR) {
+		if (ntoh24(reject->dlength) > datalen)
+			return ISCSI_ERR_PROTO;
+
+		if (ntoh24(reject->dlength) >= sizeof(struct iscsi_hdr)) {
+			memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
+			itt = rejected_pdu.itt & ISCSI_ITT_MASK;
+			printk(KERN_ERR "itt 0x%x had pdu (op 0x%x) rejected "
+				"due to DataDigest error.\n", itt,
+				rejected_pdu.opcode);
+		}
+	}
+	return 0;
+}
+
 /**
  * __iscsi_complete_pdu - complete pdu
  * @conn: iscsi conn
@@ -436,6 +460,11 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 			break;
 		}
 	} else if (itt == ISCSI_RESERVED_TAG) {
+		rc = iscsi_check_assign_cmdsn(session,
+					     (struct iscsi_nopin*)hdr);
+		if (rc)
+			goto done;
+
 		switch(opcode) {
 		case ISCSI_OP_NOOP_IN:
 			if (datalen) {
@@ -443,11 +472,6 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 				break;
 			}
 
-			rc = iscsi_check_assign_cmdsn(session,
-						 (struct iscsi_nopin*)hdr);
-			if (rc)
-				break;
-
 			if (hdr->ttt == ISCSI_RESERVED_TAG)
 				break;
 
@@ -455,7 +479,8 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 				rc = ISCSI_ERR_CONN_FAILED;
 			break;
 		case ISCSI_OP_REJECT:
-			/* we need sth like iscsi_reject_rsp()*/
+			rc = iscsi_handle_reject(conn, hdr, data, datalen);
+			break;
 		case ISCSI_OP_ASYNC_EVENT:
 			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
 			/* we need sth like iscsi_async_event_rsp() */