scsi: target: core: Add emulation for REPORT IDENTIFYING INFORMATION

Add emulation for REPORT IDENTIFYING INFORMATION command using the
configfs file 'pd_text_id_info' in target core module. The configfs file
is created in /sys/kernel/config/target/core/<backend type>/
<backing_store_name>/wwn/.

An emulation function, spc_emulate_report_id_info(), is defined to
return the identification string based on the contents of
'pd_text_id_info'.

The details of the REPORT IDENTIFYING INFORMATION command is defined in
section 6.32 of SPC4.

[mkp: checkpatch tweaks]

Signed-off-by: Gulam Mohamed <gulam.mohamed@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://patch.msgid.link/20251201110716.227588-1-gulam.mohamed@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

3 files changed, 140 insertions, 0 deletions

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index f7868b41c5e6..eb5bc3f1673b 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -1741,6 +1741,54 @@ static ssize_t target_wwn_vpd_protocol_identifier_show(struct config_item *item,
 	return len;
 }
 
+static ssize_t target_wwn_pd_text_id_info_show(struct config_item *item,
+		char *page)
+{
+	return sysfs_emit(page, "%s\n", &to_t10_wwn(item)->pd_text_id_info[0]);
+}
+
+static ssize_t target_wwn_pd_text_id_info_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct t10_wwn *t10_wwn = to_t10_wwn(item);
+	struct se_device *dev = t10_wwn->t10_dev;
+
+	/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
+	unsigned char buf[PD_TEXT_ID_INFO_LEN + 2];
+	char *stripped;
+
+	/*
+	 * Check to see if any active exports exist.  If they do exist, fail
+	 * here as changing this information on the fly (underneath the
+	 * initiator side OS dependent multipath code) could cause negative
+	 * effects.
+	 */
+	if (dev->export_count) {
+		pr_err("Unable to set the peripheral device text id info while active %d exports exist\n",
+			dev->export_count);
+		return -EINVAL;
+	}
+
+	if (strscpy(buf, page, sizeof(buf)) < 0)
+		return -EOVERFLOW;
+
+	/* Strip any newline added from userspace. */
+	stripped = strstrip(buf);
+	if (strlen(stripped) >= PD_TEXT_ID_INFO_LEN) {
+		pr_err("Emulated peripheral device text id info exceeds PD_TEXT_ID_INFO_LEN: " __stringify(PD_TEXT_ID_INFO_LEN "\n"));
+		return -EOVERFLOW;
+	}
+
+	BUILD_BUG_ON(sizeof(dev->t10_wwn.pd_text_id_info) != PD_TEXT_ID_INFO_LEN);
+	strscpy(dev->t10_wwn.pd_text_id_info, stripped,
+	       sizeof(dev->t10_wwn.pd_text_id_info));
+
+	pr_debug("Target_Core_ConfigFS: Set emulated peripheral dev text id info:"
+		  " %s\n", dev->t10_wwn.pd_text_id_info);
+
+	return count;
+}
+
 /*
  * Generic wrapper for dumping VPD identifiers by association.
  */
@@ -1797,6 +1845,7 @@ CONFIGFS_ATTR_RO(target_wwn_, vpd_protocol_identifier);
 CONFIGFS_ATTR_RO(target_wwn_, vpd_assoc_logical_unit);
 CONFIGFS_ATTR_RO(target_wwn_, vpd_assoc_target_port);
 CONFIGFS_ATTR_RO(target_wwn_, vpd_assoc_scsi_target_device);
+CONFIGFS_ATTR(target_wwn_, pd_text_id_info);
 
 static struct configfs_attribute *target_core_dev_wwn_attrs[] = {
 	&target_wwn_attr_vendor_id,
@@ -1808,6 +1857,7 @@ static struct configfs_attribute *target_core_dev_wwn_attrs[] = {
 	&target_wwn_attr_vpd_assoc_logical_unit,
 	&target_wwn_attr_vpd_assoc_target_port,
 	&target_wwn_attr_vpd_assoc_scsi_target_device,
+	&target_wwn_attr_pd_text_id_info,
 	NULL,
 };
 
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index fe2b888bcb43..f20bc6ea019b 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -25,6 +25,8 @@
 #include "target_core_ua.h"
 #include "target_core_xcopy.h"
 
+#define PD_TEXT_ID_INFO_HDR_LEN	4
+
 static void spc_fill_alua_data(struct se_lun *lun, unsigned char *buf)
 {
 	struct t10_alua_tg_pt_gp *tg_pt_gp;
@@ -1999,6 +2001,18 @@ static const struct target_opcode_descriptor tcm_opcode_report_supp_opcodes = {
 	.enabled = spc_rsoc_enabled,
 };
 
+static struct target_opcode_descriptor tcm_opcode_report_identifying_information = {
+	.support = SCSI_SUPPORT_FULL,
+	.serv_action_valid = 1,
+	.opcode = MAINTENANCE_IN,
+	.service_action = MI_REPORT_IDENTIFYING_INFORMATION,
+	.cdb_size = 12,
+	.usage_bits = {MAINTENANCE_IN, MI_REPORT_IDENTIFYING_INFORMATION,
+		       0x00, 0x00,
+		       0x00, 0x00, 0xff, 0xff,
+		       0xff, 0xff, 0xff, SCSI_CONTROL_MASK},
+};
+
 static bool tcm_is_set_tpg_enabled(const struct target_opcode_descriptor *descr,
 				   struct se_cmd *cmd)
 {
@@ -2086,6 +2100,7 @@ static const struct target_opcode_descriptor *tcm_supported_opcodes[] = {
 	&tcm_opcode_report_target_pgs,
 	&tcm_opcode_report_supp_opcodes,
 	&tcm_opcode_set_tpg,
+	&tcm_opcode_report_identifying_information,
 };
 
 static int
@@ -2303,6 +2318,72 @@ out:
 	return ret;
 }
 
+static sense_reason_t
+spc_fill_pd_text_id_info(struct se_cmd *cmd, u8 *cdb)
+{
+	struct se_device *dev = cmd->se_dev;
+	unsigned char *buf;
+	unsigned char *rbuf;
+	u32 buf_len;
+	u16 data_len;
+
+	buf_len = get_unaligned_be32(&cdb[6]);
+	if (buf_len < PD_TEXT_ID_INFO_HDR_LEN)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+	data_len = strlen(dev->t10_wwn.pd_text_id_info);
+	if (data_len > 0)
+		/* trailing null */
+		data_len += 1;
+
+	data_len = data_len + PD_TEXT_ID_INFO_HDR_LEN;
+
+	if (data_len < buf_len)
+		buf_len = data_len;
+
+	buf = kzalloc(buf_len, GFP_KERNEL);
+	if (!buf) {
+		pr_err("Unable to allocate response buffer for IDENTITY INFO\n");
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	}
+
+	scnprintf(&buf[PD_TEXT_ID_INFO_HDR_LEN], buf_len - PD_TEXT_ID_INFO_HDR_LEN, "%s",
+		 dev->t10_wwn.pd_text_id_info);
+
+	put_unaligned_be16(data_len, &buf[2]);
+
+	rbuf = transport_kmap_data_sg(cmd);
+	if (!rbuf) {
+		pr_err("transport_kmap_data_sg() failed in %s\n", __func__);
+		kfree(buf);
+		return TCM_OUT_OF_RESOURCES;
+	}
+
+	memcpy(rbuf, buf, buf_len);
+	transport_kunmap_data_sg(cmd);
+	kfree(buf);
+
+	target_complete_cmd_with_length(cmd, SAM_STAT_GOOD, buf_len);
+	return TCM_NO_SENSE;
+}
+
+static sense_reason_t
+spc_emulate_report_id_info(struct se_cmd *cmd)
+{
+	u8 *cdb = cmd->t_task_cdb;
+	sense_reason_t rc;
+
+	switch ((cdb[10] >> 1)) {
+	case 2:
+		rc = spc_fill_pd_text_id_info(cmd, cdb);
+		break;
+	default:
+		return TCM_UNSUPPORTED_SCSI_OPCODE;
+	}
+
+	return rc;
+}
+
 sense_reason_t
 spc_parse_cdb(struct se_cmd *cmd, unsigned int *size)
 {
@@ -2442,6 +2523,11 @@ spc_parse_cdb(struct se_cmd *cmd, unsigned int *size)
 			    MI_REPORT_SUPPORTED_OPERATION_CODES)
 				cmd->execute_cmd =
 					spc_emulate_report_supp_op_codes;
+			if ((cdb[1] & 0x1f) ==
+			    MI_REPORT_IDENTIFYING_INFORMATION) {
+				cmd->execute_cmd =
+					spc_emulate_report_id_info;
+			}
 			*size = get_unaligned_be32(&cdb[6]);
 		} else {
 			/*
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 7016d93fa383..b62d5fcce950 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -108,6 +108,9 @@
 #define SE_MODE_PAGE_BUF			512
 #define SE_SENSE_BUF				96
 
+/* Peripheral Device Text Identification Information */
+#define PD_TEXT_ID_INFO_LEN			256
+
 enum target_submit_type {
 	/* Use the fabric driver's default submission type */
 	TARGET_FABRIC_DEFAULT_SUBMIT,
@@ -348,6 +351,7 @@ struct t10_wwn {
 	struct se_device *t10_dev;
 	struct config_group t10_wwn_group;
 	struct list_head t10_vpd_list;
+	char pd_text_id_info[PD_TEXT_ID_INFO_LEN];
 };
 
 struct t10_pr_registration {