acpi/nfit, libnvdimm: Introduce nvdimm_security_ops

Some NVDIMMs, like the ones defined by the NVDIMM_FAMILY_INTEL command
set, expose a security capability to lock the DIMMs at poweroff and
require a passphrase to unlock them. The security model is derived from
ATA security. In anticipation of other DIMMs implementing a similar
scheme, and to abstract the core security implementation away from the
device-specific details, introduce nvdimm_security_ops.

Initially only a status retrieval operation, ->state(), is defined,
along with the base infrastructure and definitions for future
operations.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

3 files changed, 63 insertions, 1 deletions

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 9743d8083538..eae17d8ee539 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -331,6 +331,12 @@ struct nvdimm_bus *to_nvdimm_bus(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(to_nvdimm_bus);
 
+struct nvdimm_bus *nvdimm_to_bus(struct nvdimm *nvdimm)
+{
+	return to_nvdimm_bus(nvdimm->dev.parent);
+}
+EXPORT_SYMBOL_GPL(nvdimm_to_bus);
+
 struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
 		struct nvdimm_bus_descriptor *nd_desc)
 {
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 508dd405f84f..9609b671311b 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -370,23 +370,60 @@ static ssize_t available_slots_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(available_slots);
 
+static ssize_t security_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nvdimm *nvdimm = to_nvdimm(dev);
+
+	switch (nvdimm->sec.state) {
+	case NVDIMM_SECURITY_DISABLED:
+		return sprintf(buf, "disabled\n");
+	case NVDIMM_SECURITY_UNLOCKED:
+		return sprintf(buf, "unlocked\n");
+	case NVDIMM_SECURITY_LOCKED:
+		return sprintf(buf, "locked\n");
+	case NVDIMM_SECURITY_FROZEN:
+		return sprintf(buf, "frozen\n");
+	case NVDIMM_SECURITY_OVERWRITE:
+		return sprintf(buf, "overwrite\n");
+	}
+
+	return -ENOTTY;
+}
+static DEVICE_ATTR_RO(security);
+
 static struct attribute *nvdimm_attributes[] = {
 	&dev_attr_state.attr,
 	&dev_attr_flags.attr,
 	&dev_attr_commands.attr,
 	&dev_attr_available_slots.attr,
+	&dev_attr_security.attr,
 	NULL,
 };
 
+static umode_t nvdimm_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, typeof(*dev), kobj);
+	struct nvdimm *nvdimm = to_nvdimm(dev);
+
+	if (a != &dev_attr_security.attr)
+		return a->mode;
+	if (nvdimm->sec.state < 0)
+		return 0;
+	return a->mode;
+}
+
 struct attribute_group nvdimm_attribute_group = {
 	.attrs = nvdimm_attributes,
+	.is_visible = nvdimm_visible,
 };
 EXPORT_SYMBOL_GPL(nvdimm_attribute_group);
 
 struct nvdimm *__nvdimm_create(struct nvdimm_bus *nvdimm_bus,
 		void *provider_data, const struct attribute_group **groups,
 		unsigned long flags, unsigned long cmd_mask, int num_flush,
-		struct resource *flush_wpq, const char *dimm_id)
+		struct resource *flush_wpq, const char *dimm_id,
+		const struct nvdimm_security_ops *sec_ops)
 {
 	struct nvdimm *nvdimm = kzalloc(sizeof(*nvdimm), GFP_KERNEL);
 	struct device *dev;
@@ -413,6 +450,12 @@ struct nvdimm *__nvdimm_create(struct nvdimm_bus *nvdimm_bus,
 	dev->type = &nvdimm_device_type;
 	dev->devt = MKDEV(nvdimm_major, nvdimm->id);
 	dev->groups = groups;
+	nvdimm->sec.ops = sec_ops;
+	/*
+	 * Security state must be initialized before device_add() for
+	 * attribute visibility.
+	 */
+	nvdimm->sec.state = nvdimm_security_state(nvdimm);
 	nd_device_register(dev);
 
 	return nvdimm;
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index ff26876e6ea3..1919f5c0d581 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -42,8 +42,21 @@ struct nvdimm {
 	int id, num_flush;
 	struct resource *flush_wpq;
 	const char *dimm_id;
+	struct {
+		const struct nvdimm_security_ops *ops;
+		enum nvdimm_security_state state;
+	} sec;
 };
 
+static inline enum nvdimm_security_state nvdimm_security_state(
+		struct nvdimm *nvdimm)
+{
+	if (!nvdimm->sec.ops)
+		return -ENXIO;
+
+	return nvdimm->sec.ops->state(nvdimm);
+}
+
 /**
  * struct blk_alloc_info - tracking info for BLK dpa scanning
  * @nd_mapping: blk region mapping boundaries