[PATCH v15 09/16] acpi/nfit, libnvdimm: Add enable/update passphrase support for Intel nvdimms

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

Add support for enabling and updating passphrase on the Intel nvdimms.
The passphrase is the an encrypted key in the kernel user keyring.
We trigger the update via writing "update <old_keyid> <new_keyid>" to the
sysfs attribute "security". If no <old_keyid> exists (for enabling
security) then a 0 should be used.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/dimm_devs.c |   11 ++++++--
 drivers/nvdimm/nd-core.h   |    2 ++
 drivers/nvdimm/security.c  |   58 +++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 7f42cc4e119b..1cc3a6af3d0e 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -392,8 +392,9 @@ static ssize_t security_show(struct device *dev,
 }
 
 #define OPS						\
-	C( OP_FREEZE,        "freeze",        1),	\
-	C( OP_DISABLE,       "disable",       2)
+	C( OP_FREEZE,		"freeze",	1),	\
+	C( OP_DISABLE,		"disable",	2),	\
+	C( OP_UPDATE,		"update",	3)
 #undef C
 #define C(a, b, c) a
 enum nvdimmsec_op_ids { OPS };
@@ -444,6 +445,9 @@ static ssize_t __security_store(struct device *dev, const char *buf, size_t len)
 	} else if (i == OP_DISABLE) {
 		dev_dbg(dev, "disable %u\n", key);
 		rc = nvdimm_security_disable(nvdimm, key);
+	} else if (i == OP_UPDATE) {
+		dev_dbg(dev, "update %u %u\n", key, newkey);
+		rc = nvdimm_security_update(nvdimm, key, newkey);
 	} else
 		return -EINVAL;
 
@@ -493,7 +497,8 @@ static umode_t nvdimm_visible(struct kobject *kobj, struct attribute *a, int n)
 	if (nvdimm->sec.state < 0)
 		return 0;
 	/* Are there any state mutation ops? */
-	if (nvdimm->sec.ops->freeze || nvdimm->sec.ops->disable)
+	if (nvdimm->sec.ops->freeze || nvdimm->sec.ops->disable
+			|| nvdimm->sec.ops->change_key)
 		return a->mode;
 	return 0444;
 }
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index 93e63c12ea45..ca020793a419 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -58,6 +58,8 @@ static inline enum nvdimm_security_state nvdimm_security_state(
 }
 int nvdimm_security_freeze(struct nvdimm *nvdimm);
 int nvdimm_security_disable(struct nvdimm *nvdimm, unsigned int keyid);
+int nvdimm_security_update(struct nvdimm *nvdimm, unsigned int keyid,
+		unsigned int new_keyid);
 
 /**
  * struct blk_alloc_info - tracking info for BLK dpa scanning
diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
index 55d8806a5040..654b64fe7e9d 100644
--- a/drivers/nvdimm/security.c
+++ b/drivers/nvdimm/security.c
@@ -15,6 +15,9 @@
 #include "nd-core.h"
 #include "nd.h"
 
+#define NVDIMM_BASE_KEY		0
+#define NVDIMM_NEW_KEY		1
+
 static bool key_revalidate = true;
 module_param(key_revalidate, bool, 0444);
 MODULE_PARM_DESC(key_revalidate, "Require key validation at init.");
@@ -70,7 +73,7 @@ static struct key *nvdimm_request_key(struct nvdimm *nvdimm)
 }
 
 static struct key *nvdimm_lookup_user_key(struct nvdimm *nvdimm,
-		key_serial_t id)
+		key_serial_t id, int subclass)
 {
 	key_ref_t keyref;
 	struct key *key;
@@ -86,10 +89,10 @@ static struct key *nvdimm_lookup_user_key(struct nvdimm *nvdimm,
 		key_put(key);
 		return NULL;
 	}
-	dev_dbg(dev, "%s: key found: %#x\n", __func__, key_serial(key));
 
+	dev_dbg(dev, "%s: key found: %#x\n", __func__, key_serial(key));
 
-	down_read(&key->sem);
+	down_read_nested(&key->sem, subclass);
 	epayload = dereference_key_locked(key);
 	if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
 		up_read(&key->sem);
@@ -197,7 +200,7 @@ int nvdimm_security_disable(struct nvdimm *nvdimm, unsigned int keyid)
 		return -EIO;
 	}
 
-	key = nvdimm_lookup_user_key(nvdimm, keyid);
+	key = nvdimm_lookup_user_key(nvdimm, keyid, NVDIMM_BASE_KEY);
 	if (!key)
 		return -ENOKEY;
 
@@ -209,3 +212,50 @@ int nvdimm_security_disable(struct nvdimm *nvdimm, unsigned int keyid)
 	nvdimm->sec.state = nvdimm_security_state(nvdimm);
 	return rc;
 }
+
+int nvdimm_security_update(struct nvdimm *nvdimm, unsigned int keyid,
+		unsigned int new_keyid)
+{
+	struct device *dev = &nvdimm->dev;
+	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+	struct key *key, *newkey;
+	int rc;
+
+	/* The bus lock should be held at the top level of the call stack */
+	lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
+
+	if (!nvdimm->sec.ops || !nvdimm->sec.ops->change_key
+			|| nvdimm->sec.state < 0)
+		return -EIO;
+
+	if (nvdimm->sec.state >= NVDIMM_SECURITY_FROZEN) {
+		dev_warn(dev, "Incorrect security state: %d\n",
+				nvdimm->sec.state);
+		return -EIO;
+	}
+
+	if (keyid == 0)
+		key = NULL;
+	else {
+		key = nvdimm_lookup_user_key(nvdimm, keyid, NVDIMM_BASE_KEY);
+		if (!key)
+			return -ENOKEY;
+	}
+
+	newkey = nvdimm_lookup_user_key(nvdimm, new_keyid, NVDIMM_NEW_KEY);
+	if (!newkey) {
+		nvdimm_put_key(key);
+		return -ENOKEY;
+	}
+
+	rc = nvdimm->sec.ops->change_key(nvdimm, key ? key_data(key) : NULL,
+			key_data(newkey));
+	dev_dbg(dev, "key: %d %d update: %s\n",
+			key_serial(key), key_serial(newkey),
+			rc == 0 ? "success" : "fail");
+
+	nvdimm_put_key(newkey);
+	nvdimm_put_key(key);
+	nvdimm->sec.state = nvdimm_security_state(nvdimm);
+	return rc;
+}

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