acpi/nfit, libnvdimm/security: Add security DSM overwrite support

Add support for the NVDIMM_FAMILY_INTEL "ovewrite" capability as
described by the Intel DSM spec v1.7. This will allow triggering of
overwrite on Intel NVDIMMs. The overwrite operation can take tens of
minutes. When the overwrite DSM is issued successfully, the NVDIMMs will
be unaccessible. The kernel will do backoff polling to detect when the
overwrite process is completed. According to the DSM spec v1.7, the 128G
NVDIMMs can take up to 15mins to perform overwrite and larger DIMMs will
take longer.

Given that overwrite puts the DIMM in an indeterminate state until it
completes introduce the NDD_SECURITY_OVERWRITE flag to prevent other
operations from executing when overwrite is happening. The
NDD_WORK_PENDING flag is added to denote that there is a device reference
on the nvdimm device for an async workqueue thread context.

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

1 files changed, 30 insertions, 2 deletions

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index bc432b7c17b8..6affa270abd3 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -395,7 +395,8 @@ static ssize_t security_show(struct device *dev,
 	C( OP_FREEZE,		"freeze",	1),	\
 	C( OP_DISABLE,		"disable",	2),	\
 	C( OP_UPDATE,		"update",	3),	\
-	C( OP_ERASE,		"erase",	2)
+	C( OP_ERASE,		"erase",	2),	\
+	C( OP_OVERWRITE,	"overwrite",	2)
 #undef C
 #define C(a, b, c) a
 enum nvdimmsec_op_ids { OPS };
@@ -452,6 +453,9 @@ static ssize_t __security_store(struct device *dev, const char *buf, size_t len)
 	} else if (i == OP_ERASE) {
 		dev_dbg(dev, "erase %u\n", key);
 		rc = nvdimm_security_erase(nvdimm, key);
+	} else if (i == OP_OVERWRITE) {
+		dev_dbg(dev, "overwrite %u\n", key);
+		rc = nvdimm_security_overwrite(nvdimm, key);
 	} else
 		return -EINVAL;
 
@@ -503,7 +507,8 @@ static umode_t nvdimm_visible(struct kobject *kobj, struct attribute *a, int n)
 	/* Are there any state mutation ops? */
 	if (nvdimm->sec.ops->freeze || nvdimm->sec.ops->disable
 			|| nvdimm->sec.ops->change_key
-			|| nvdimm->sec.ops->erase)
+			|| nvdimm->sec.ops->erase
+			|| nvdimm->sec.ops->overwrite)
 		return a->mode;
 	return 0444;
 }
@@ -546,6 +551,8 @@ struct nvdimm *__nvdimm_create(struct nvdimm_bus *nvdimm_bus,
 	dev->devt = MKDEV(nvdimm_major, nvdimm->id);
 	dev->groups = groups;
 	nvdimm->sec.ops = sec_ops;
+	nvdimm->sec.overwrite_tmo = 0;
+	INIT_DELAYED_WORK(&nvdimm->dwork, nvdimm_security_overwrite_query);
 	/*
 	 * Security state must be initialized before device_add() for
 	 * attribute visibility.
@@ -557,6 +564,22 @@ struct nvdimm *__nvdimm_create(struct nvdimm_bus *nvdimm_bus,
 }
 EXPORT_SYMBOL_GPL(__nvdimm_create);
 
+int nvdimm_security_setup_events(struct nvdimm *nvdimm)
+{
+	nvdimm->sec.overwrite_state = sysfs_get_dirent(nvdimm->dev.kobj.sd,
+			"security");
+	if (!nvdimm->sec.overwrite_state)
+		return -ENODEV;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvdimm_security_setup_events);
+
+int nvdimm_in_overwrite(struct nvdimm *nvdimm)
+{
+	return test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
+}
+EXPORT_SYMBOL_GPL(nvdimm_in_overwrite);
+
 int nvdimm_security_freeze(struct nvdimm *nvdimm)
 {
 	int rc;
@@ -569,6 +592,11 @@ int nvdimm_security_freeze(struct nvdimm *nvdimm)
 	if (nvdimm->sec.state < 0)
 		return -EIO;
 
+	if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
+		dev_warn(&nvdimm->dev, "Overwrite operation in progress.\n");
+		return -EBUSY;
+	}
+
 	rc = nvdimm->sec.ops->freeze(nvdimm);
 	nvdimm->sec.state = nvdimm_security_state(nvdimm);