nvmet: lock config semaphore when accessing DH-HMAC-CHAP key

When the DH-HMAC-CHAP key is accessed via configfs we need to take the
config semaphore as a reconnect might be running at the same time.
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/target/auth.c

@@ -44,6 +44,7 @@ int nvmet_auth_set_key(struct nvmet_host *host, const char *secret,
 	dhchap_secret = kstrdup(secret, GFP_KERNEL);
 	if (!dhchap_secret)
 		return -ENOMEM;
+	down_write(&nvmet_config_sem);
 	if (set_ctrl) {
 		kfree(host->dhchap_ctrl_secret);
 		host->dhchap_ctrl_secret = strim(dhchap_secret);
@@ -53,6 +54,7 @@ int nvmet_auth_set_key(struct nvmet_host *host, const char *secret,
 		host->dhchap_secret = strim(dhchap_secret);
 		host->dhchap_key_hash = key_hash;
 	}
+	up_write(&nvmet_config_sem);
 	return 0;
 }
 

drivers/nvme/target/configfs.c

@@ -1990,11 +1990,17 @@ static struct config_group nvmet_ports_group;
 static ssize_t nvmet_host_dhchap_key_show(struct config_item *item,
 		char *page)
 {
-	u8 *dhchap_secret = to_host(item)->dhchap_secret;
+	u8 *dhchap_secret;
+	ssize_t ret;
 
+	down_read(&nvmet_config_sem);
+	dhchap_secret = to_host(item)->dhchap_secret;
 	if (!dhchap_secret)
-		return sprintf(page, "\n");
-	return sprintf(page, "%s\n", dhchap_secret);
+		ret = sprintf(page, "\n");
+	else
+		ret = sprintf(page, "%s\n", dhchap_secret);
+	up_read(&nvmet_config_sem);
+	return ret;
 }
 
 static ssize_t nvmet_host_dhchap_key_store(struct config_item *item,
@@ -2018,10 +2024,16 @@ static ssize_t nvmet_host_dhchap_ctrl_key_show(struct config_item *item,
 		char *page)
 {
 	u8 *dhchap_secret = to_host(item)->dhchap_ctrl_secret;
+	ssize_t ret;
 
+	down_read(&nvmet_config_sem);
+	dhchap_secret = to_host(item)->dhchap_ctrl_secret;
 	if (!dhchap_secret)
-		return sprintf(page, "\n");
-	return sprintf(page, "%s\n", dhchap_secret);
+		ret = sprintf(page, "\n");
+	else
+		ret = sprintf(page, "%s\n", dhchap_secret);
+	up_read(&nvmet_config_sem);
+	return ret;
 }
 
 static ssize_t nvmet_host_dhchap_ctrl_key_store(struct config_item *item,