[PATCH v3 3/3] nvme-auth: always set valid seq_num in dhchap reply

[Mark O'Donovan <shiftee@posteo.net>]

Currently a seqnum of zero is sent during uni-directional
authentication. The zero value is reserved for the secure channel
feature which is not yet implemented.

Relevant extract from the spec:
The value 0h is used to indicate that bidirectional authentication
is not performed, but a challenge value C2 is carried in order to
generate a pre-shared key (PSK) for subsequent establishment of a
secure channel

Signed-off-by: Mark O'Donovan <shiftee@posteo.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>

---
v1: used incorrect prefix nvme-tcp
v2: added spec extract to commit message
v3: read the seq-num in nvme-target code

 drivers/nvme/host/auth.c               | 3 +--
 drivers/nvme/target/fabrics-cmd-auth.c | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/auth.c b/drivers/nvme/host/auth.c
index 8558a02865ac..7f6b2e99a78c 100644
--- a/drivers/nvme/host/auth.c
+++ b/drivers/nvme/host/auth.c
@@ -316,15 +316,14 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,
 		chap->bi_directional = true;
 		get_random_bytes(chap->c2, chap->hash_len);
 		data->cvalid = 1;
-		chap->s2 = nvme_auth_get_seqnum();
 		memcpy(data->rval + chap->hash_len, chap->c2,
 		       chap->hash_len);
 		dev_dbg(ctrl->device, "%s: qid %d ctrl challenge %*ph\n",
 			__func__, chap->qid, (int)chap->hash_len, chap->c2);
 	} else {
 		memset(chap->c2, 0, chap->hash_len);
-		chap->s2 = 0;
 	}
+	chap->s2 = nvme_auth_get_seqnum();
 	data->seqnum = cpu_to_le32(chap->s2);
 	if (chap->host_key_len) {
 		dev_dbg(ctrl->device, "%s: qid %d host public key %*ph\n",
diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
index 1d9854484e2e..eb7785be0ca7 100644
--- a/drivers/nvme/target/fabrics-cmd-auth.c
+++ b/drivers/nvme/target/fabrics-cmd-auth.c
@@ -163,11 +163,11 @@ static u16 nvmet_auth_reply(struct nvmet_req *req, void *d)
 		pr_debug("%s: ctrl %d qid %d challenge %*ph\n",
 			 __func__, ctrl->cntlid, req->sq->qid, data->hl,
 			 req->sq->dhchap_c2);
-		req->sq->dhchap_s2 = le32_to_cpu(data->seqnum);
 	} else {
 		req->sq->authenticated = true;
 		req->sq->dhchap_c2 = NULL;
 	}
+	req->sq->dhchap_s2 = le32_to_cpu(data->seqnum);
 
 	return 0;
 }
-- 
2.39.2