nvmet: change sn size and check validity

According to the NVM specification, the serial_number should be 20 bytes
(bytes 23:04 of the Identify Controller data structure), and should
contain only ASCII characters.

In accordance, the serial_number size is changed to 20 bytes and before
any attempt to store a new value in serial_number we check that the
input is valid - i.e. contains only ASCII characters, is not empty and
does not exceed 20 bytes.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Noam Gottlieb <ngottlieb@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/admin-cmd.c

@@ -357,9 +357,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	id->vid = 0;
 	id->ssvid = 0;
 
-	memset(id->sn, ' ', sizeof(id->sn));
-	bin2hex(id->sn, &ctrl->subsys->serial,
-		min(sizeof(ctrl->subsys->serial), sizeof(id->sn) / 2));
+	memcpy(id->sn, ctrl->subsys->serial, NVMET_SN_MAX_SIZE);
 	memcpy_and_pad(id->mn, sizeof(id->mn), subsys->model_number,
 		       strlen(subsys->model_number), ' ');
 	memcpy_and_pad(id->fr, sizeof(id->fr),

drivers/nvme/target/configfs.c

@@ -1030,24 +1030,43 @@ static ssize_t nvmet_subsys_attr_version_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_version);
 
+/* See Section 1.5 of NVMe 1.4 */
+static bool nvmet_is_ascii(const char c)
+{
+	return c >= 0x20 && c <= 0x7e;
+}
+
 static ssize_t nvmet_subsys_attr_serial_show(struct config_item *item,
 					     char *page)
 {
 	struct nvmet_subsys *subsys = to_subsys(item);
 
-	return snprintf(page, PAGE_SIZE, "%llx\n", subsys->serial);
+	return snprintf(page, PAGE_SIZE, "%s\n", subsys->serial);
 }
 
 static ssize_t nvmet_subsys_attr_serial_store(struct config_item *item,
 					      const char *page, size_t count)
 {
-	u64 serial;
+	struct nvmet_subsys *subsys = to_subsys(item);
+	int pos, len = strcspn(page, "\n");
 
-	if (sscanf(page, "%llx\n", &serial) != 1)
+	if (!len || len > NVMET_SN_MAX_SIZE) {
+		pr_err("Serial Number can not be empty or exceed %d Bytes\n",
+		       NVMET_SN_MAX_SIZE);
 		return -EINVAL;
+	}
+
+	for (pos = 0; pos < len; pos++) {
+		if (!nvmet_is_ascii(page[pos])) {
+			pr_err("Serial Number must contain only ASCII strings\n");
+			return -EINVAL;
+		}
+	}
 
 	down_write(&nvmet_config_sem);
-	to_subsys(item)->serial = serial;
+	mutex_lock(&subsys->lock);
+	memcpy_and_pad(subsys->serial, NVMET_SN_MAX_SIZE, page, len, ' ');
+	mutex_unlock(&subsys->lock);
 	up_write(&nvmet_config_sem);
 
 	return count;
@@ -1128,12 +1147,6 @@ static ssize_t nvmet_subsys_attr_model_show(struct config_item *item,
 	return ret;
 }
 
-/* See Section 1.5 of NVMe 1.4 */
-static bool nvmet_is_ascii(const char c)
-{
-	return c >= 0x20 && c <= 0x7e;
-}
-
 static ssize_t nvmet_subsys_attr_model_store_locked(struct nvmet_subsys *subsys,
 		const char *page, size_t count)
 {

drivers/nvme/target/core.c

@@ -1493,6 +1493,7 @@ struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
 		enum nvme_subsys_type type)
 {
 	struct nvmet_subsys *subsys;
+	char serial[NVMET_SN_MAX_SIZE / 2];
 
 	subsys = kzalloc(sizeof(*subsys), GFP_KERNEL);
 	if (!subsys)
@@ -1500,7 +1501,8 @@ struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
 
 	subsys->ver = NVMET_DEFAULT_VS;
 	/* generate a random serial number as our controllers are ephemeral: */
-	get_random_bytes(&subsys->serial, sizeof(subsys->serial));
+	get_random_bytes(&serial, sizeof(serial));
+	bin2hex(subsys->serial, &serial, sizeof(serial));
 
 	switch (type) {
 	case NVME_NQN_NVME:

drivers/nvme/target/discovery.c

@@ -262,9 +262,7 @@ static void nvmet_execute_disc_identify(struct nvmet_req *req)
 		goto out;
 	}
 
-	memset(id->sn, ' ', sizeof(id->sn));
-	bin2hex(id->sn, &ctrl->subsys->serial,
-		min(sizeof(ctrl->subsys->serial), sizeof(id->sn) / 2));
+	memcpy(id->sn, ctrl->subsys->serial, NVMET_SN_MAX_SIZE);
 	memset(id->fr, ' ', sizeof(id->fr));
 	memcpy_and_pad(id->mn, sizeof(id->mn), model, sizeof(model) - 1, ' ');
 	memcpy_and_pad(id->fr, sizeof(id->fr),

drivers/nvme/target/nvmet.h

@@ -28,6 +28,7 @@
 #define NVMET_NO_ERROR_LOC		((u16)-1)
 #define NVMET_DEFAULT_CTRL_MODEL	"Linux"
 #define NVMET_MN_MAX_SIZE		40
+#define NVMET_SN_MAX_SIZE		20
 
 /*
  * Supported optional AENs:
@@ -229,7 +230,7 @@ struct nvmet_subsys {
 	u16			max_qid;
 
 	u64			ver;
-	u64			serial;
+	char			serial[NVMET_SN_MAX_SIZE];
 	char			*subsysnqn;
 	bool			pi_support;