libnvdimm/security: Introduce a 'frozen' attribute

In the process of debugging a system with an NVDIMM that was failing to
unlock it was found that the kernel is reporting 'locked' while the DIMM
security interface is 'frozen'. Unfortunately the security state is
tracked internally as an enum which prevents it from communicating the
difference between 'locked' and 'locked + frozen'. It follows that the
enum also prevents the kernel from communicating 'unlocked + frozen'
which would be useful for debugging why security operations like 'change
passphrase' are disabled.

Ditch the security state enum for a set of flags and introduce a new
sysfs attribute explicitly for the 'frozen' state. The regression risk
is low because the 'frozen' state was already blocked behind the
'locked' state, but will need to revisit if there were cases where
applications need 'frozen' to show up in the primary 'security'
attribute. The expectation is that communicating 'frozen' is mostly a
helper for debug and status monitoring.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Link: https://lore.kernel.org/r/156686729474.184120.5835135644278860826.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index 0ac52b6eb00e..da2bbfd56d9f 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -39,21 +39,32 @@ struct nvdimm {
 	const char *dimm_id;
 	struct {
 		const struct nvdimm_security_ops *ops;
-		enum nvdimm_security_state state;
-		enum nvdimm_security_state ext_state;
+		unsigned long flags;
+		unsigned long ext_flags;
 		unsigned int overwrite_tmo;
 		struct kernfs_node *overwrite_state;
 	} sec;
 	struct delayed_work dwork;
 };
 
-static inline enum nvdimm_security_state nvdimm_security_state(
+static inline unsigned long nvdimm_security_flags(
 		struct nvdimm *nvdimm, enum nvdimm_passphrase_type ptype)
 {
+	u64 flags;
+	const u64 state_flags = 1UL << NVDIMM_SECURITY_DISABLED
+		| 1UL << NVDIMM_SECURITY_LOCKED
+		| 1UL << NVDIMM_SECURITY_UNLOCKED
+		| 1UL << NVDIMM_SECURITY_OVERWRITE;
+
 	if (!nvdimm->sec.ops)
-		return -ENXIO;
+		return 0;
 
-	return nvdimm->sec.ops->state(nvdimm, ptype);
+	flags = nvdimm->sec.ops->get_flags(nvdimm, ptype);
+	/* disabled, locked, unlocked, and overwrite are mutually exclusive */
+	dev_WARN_ONCE(&nvdimm->dev, hweight64(flags & state_flags) > 1,
+			"reported invalid security state: %#llx\n",
+			(unsigned long long) flags);
+	return flags;
 }
 int nvdimm_security_freeze(struct nvdimm *nvdimm);
 #if IS_ENABLED(CONFIG_NVDIMM_KEYS)