[PATCH v4 1/2] libnvdimm/security: Support a zero-key for secure-erase

[Dave Jiang <dave.jiang@intel.com>]

Adding support to allow secure erase to happen when security state is not
enabled. Key data of 0's will be passed in.

Some other security commands already use zero keys. This is to unifiy
semantics cross commands with respect to using zero keys.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v4: No change

v3:
- Add note in commit header about syncing zero key usage. (Dan)

v2:
- Make patch header explicitly zero key (Dan)
- Declare global static zero key (Dan)
- Make nfit_test explicitly test zero key (Dan)

 drivers/nvdimm/security.c        |   17 ++++++++++++-----
 tools/testing/nvdimm/test/nfit.c |   11 +++++++++--
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
index f8bb746a549f..6bea6852bf27 100644
--- a/drivers/nvdimm/security.c
+++ b/drivers/nvdimm/security.c
@@ -22,6 +22,8 @@ static bool key_revalidate = true;
 module_param(key_revalidate, bool, 0444);
 MODULE_PARM_DESC(key_revalidate, "Require key validation at init.");
 
+static const char zero_key[NVDIMM_PASSPHRASE_LEN];
+
 static void *key_data(struct key *key)
 {
 	struct encrypted_key_payload *epayload = dereference_key_locked(key);
@@ -286,8 +288,9 @@ int nvdimm_security_erase(struct nvdimm *nvdimm, unsigned int keyid,
 {
 	struct device *dev = &nvdimm->dev;
 	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
-	struct key *key;
+	struct key *key = NULL;
 	int rc;
+	const void *data;
 
 	/* The bus lock should be held at the top level of the call stack */
 	lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
@@ -319,11 +322,15 @@ int nvdimm_security_erase(struct nvdimm *nvdimm, unsigned int keyid,
 		return -EOPNOTSUPP;
 	}
 
-	key = nvdimm_lookup_user_key(nvdimm, keyid, NVDIMM_BASE_KEY);
-	if (!key)
-		return -ENOKEY;
+	if (keyid != 0) {
+		key = nvdimm_lookup_user_key(nvdimm, keyid, NVDIMM_BASE_KEY);
+		if (!key)
+			return -ENOKEY;
+		data = key_data(key);
+	} else
+		data = zero_key;
 
-	rc = nvdimm->sec.ops->erase(nvdimm, key_data(key), pass_type);
+	rc = nvdimm->sec.ops->erase(nvdimm, data, pass_type);
 	dev_dbg(dev, "key: %d erase%s: %s\n", key_serial(key),
 			pass_type == NVDIMM_MASTER ? "(master)" : "(user)",
 			rc == 0 ? "success" : "fail");
diff --git a/tools/testing/nvdimm/test/nfit.c b/tools/testing/nvdimm/test/nfit.c
index b579f962451d..cad719876ef4 100644
--- a/tools/testing/nvdimm/test/nfit.c
+++ b/tools/testing/nvdimm/test/nfit.c
@@ -225,6 +225,8 @@ static struct workqueue_struct *nfit_wq;
 
 static struct gen_pool *nfit_pool;
 
+static const char zero_key[NVDIMM_PASSPHRASE_LEN];
+
 static struct nfit_test *to_nfit_test(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -1059,8 +1061,7 @@ static int nd_intel_test_cmd_secure_erase(struct nfit_test *t,
 	struct device *dev = &t->pdev.dev;
 	struct nfit_test_sec *sec = &dimm_sec_info[dimm];
 
-	if (!(sec->state & ND_INTEL_SEC_STATE_ENABLED) ||
-			(sec->state & ND_INTEL_SEC_STATE_FROZEN)) {
+	if (sec->state & ND_INTEL_SEC_STATE_FROZEN) {
 		nd_cmd->status = ND_INTEL_STATUS_INVALID_STATE;
 		dev_dbg(dev, "secure erase: wrong security state\n");
 	} else if (memcmp(nd_cmd->passphrase, sec->passphrase,
@@ -1068,6 +1069,12 @@ static int nd_intel_test_cmd_secure_erase(struct nfit_test *t,
 		nd_cmd->status = ND_INTEL_STATUS_INVALID_PASS;
 		dev_dbg(dev, "secure erase: wrong passphrase\n");
 	} else {
+		if (!(sec->state & ND_INTEL_SEC_STATE_ENABLED)
+				&& (memcmp(nd_cmd->passphrase, zero_key,
+					ND_INTEL_PASSPHRASE_SIZE) != 0)) {
+			dev_dbg(dev, "invalid zero key\n");
+			return 0;
+		}
 		memset(sec->passphrase, 0, ND_INTEL_PASSPHRASE_SIZE);
 		memset(sec->master_passphrase, 0, ND_INTEL_PASSPHRASE_SIZE);
 		sec->state = 0;

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