nvme-auth: don't keep long lived 4k dhchap buffer

dhchap structure is per-queue, it is wasteful to keep it for the entire
lifetime of the queue. Allocate it dynamically and get rid of it after
authentication. We don't need kzalloc because all accessors are clearing
it before writing to it.

Also, remove redundant chap buf_size which is always 4096, use a define
instead.
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/auth.c

@@ -13,6 +13,8 @@
 #include "fabrics.h"
 #include <linux/nvme-auth.h>
 
+#define CHAP_BUF_SIZE 4096
+
 struct nvme_dhchap_queue_context {
 	struct list_head entry;
 	struct work_struct auth_work;
@@ -20,7 +22,6 @@ struct nvme_dhchap_queue_context {
 	struct crypto_shash *shash_tfm;
 	struct crypto_kpp *dh_tfm;
 	void *buf;
-	size_t buf_size;
 	int qid;
 	int error;
 	u32 s1;
@@ -112,7 +113,7 @@ static int nvme_auth_set_dhchap_negotiate_data(struct nvme_ctrl *ctrl,
 	struct nvmf_auth_dhchap_negotiate_data *data = chap->buf;
 	size_t size = sizeof(*data) + sizeof(union nvmf_auth_protocol);
 
-	if (chap->buf_size < size) {
+	if (size > CHAP_BUF_SIZE) {
 		chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
 		return -EINVAL;
 	}
@@ -147,7 +148,7 @@ static int nvme_auth_process_dhchap_challenge(struct nvme_ctrl *ctrl,
 	const char *gid_name = nvme_auth_dhgroup_name(data->dhgid);
 	const char *hmac_name, *kpp_name;
 
-	if (chap->buf_size < size) {
+	if (size > CHAP_BUF_SIZE) {
 		chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
 		return NVME_SC_INVALID_FIELD;
 	}
@@ -302,7 +303,7 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,
 	if (chap->host_key_len)
 		size += chap->host_key_len;
 
-	if (chap->buf_size < size) {
+	if (size > CHAP_BUF_SIZE) {
 		chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
 		return -EINVAL;
 	}
@@ -347,7 +348,7 @@ static int nvme_auth_process_dhchap_success1(struct nvme_ctrl *ctrl,
 	if (ctrl->ctrl_key)
 		size += chap->hash_len;
 
-	if (chap->buf_size < size) {
+	if (size > CHAP_BUF_SIZE) {
 		chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
 		return NVME_SC_INVALID_FIELD;
 	}
@@ -674,6 +675,8 @@ static void nvme_auth_reset_dhchap(struct nvme_dhchap_queue_context *chap)
 	chap->transaction = 0;
 	memset(chap->c1, 0, sizeof(chap->c1));
 	memset(chap->c2, 0, sizeof(chap->c2));
+	kfree(chap->buf);
+	chap->buf = NULL;
 }
 
 static void nvme_auth_free_dhchap(struct nvme_dhchap_queue_context *chap)
@@ -683,7 +686,6 @@ static void nvme_auth_free_dhchap(struct nvme_dhchap_queue_context *chap)
 		crypto_free_shash(chap->shash_tfm);
 	if (chap->dh_tfm)
 		crypto_free_kpp(chap->dh_tfm);
-	kfree(chap->buf);
 	kfree(chap);
 }
 
@@ -695,6 +697,16 @@ static void nvme_queue_auth_work(struct work_struct *work)
 	size_t tl;
 	int ret = 0;
 
+	/*
+	 * Allocate a large enough buffer for the entire negotiation:
+	 * 4k is enough to ffdhe8192.
+	 */
+	chap->buf = kmalloc(CHAP_BUF_SIZE, GFP_KERNEL);
+	if (!chap->buf) {
+		chap->error = -ENOMEM;
+		return;
+	}
+
 	chap->transaction = ctrl->transaction++;
 
 	/* DH-HMAC-CHAP Step 1: send negotiate */
@@ -716,8 +728,9 @@ static void nvme_queue_auth_work(struct work_struct *work)
 	dev_dbg(ctrl->device, "%s: qid %d receive challenge\n",
 		__func__, chap->qid);
 
-	memset(chap->buf, 0, chap->buf_size);
-	ret = nvme_auth_submit(ctrl, chap->qid, chap->buf, chap->buf_size, false);
+	memset(chap->buf, 0, CHAP_BUF_SIZE);
+	ret = nvme_auth_submit(ctrl, chap->qid, chap->buf, CHAP_BUF_SIZE,
+			       false);
 	if (ret) {
 		dev_warn(ctrl->device,
 			 "qid %d failed to receive challenge, %s %d\n",
@@ -779,8 +792,9 @@ static void nvme_queue_auth_work(struct work_struct *work)
 	dev_dbg(ctrl->device, "%s: qid %d receive success1\n",
 		__func__, chap->qid);
 
-	memset(chap->buf, 0, chap->buf_size);
-	ret = nvme_auth_submit(ctrl, chap->qid, chap->buf, chap->buf_size, false);
+	memset(chap->buf, 0, CHAP_BUF_SIZE);
+	ret = nvme_auth_submit(ctrl, chap->qid, chap->buf, CHAP_BUF_SIZE,
+			       false);
 	if (ret) {
 		dev_warn(ctrl->device,
 			 "qid %d failed to receive success1, %s %d\n",
@@ -876,19 +890,6 @@ int nvme_auth_negotiate(struct nvme_ctrl *ctrl, int qid)
 	}
 	chap->qid = qid;
 	chap->ctrl = ctrl;
-
-	/*
-	 * Allocate a large enough buffer for the entire negotiation:
-	 * 4k should be enough to ffdhe8192.
-	 */
-	chap->buf_size = 4096;
-	chap->buf = kzalloc(chap->buf_size, GFP_KERNEL);
-	if (!chap->buf) {
-		mutex_unlock(&ctrl->dhchap_auth_mutex);
-		kfree(chap);
-		return -ENOMEM;
-	}
-
 	INIT_WORK(&chap->auth_work, nvme_queue_auth_work);
 	list_add(&chap->entry, &ctrl->dhchap_auth_list);
 	mutex_unlock(&ctrl->dhchap_auth_mutex);