acpi/nfit, libnvdimm: Add unlock of nvdimm support for Intel DIMMs

Add support to unlock the dimm via the kernel key management APIs. The
passphrase is expected to be pulled from userspace through keyutils.
The key management and sysfs attributes are libnvdimm generic.

Encrypted keys are used to protect the nvdimm passphrase at rest. The
master key can be a trusted-key sealed in a TPM, preferred, or an
encrypted-key, more flexible, but more exposure to a potential attacker.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 109 insertions, 0 deletions

diff --git a/drivers/acpi/nfit/intel.c b/drivers/acpi/nfit/intel.c
index f98d680d1a39..38f2cb364853 100644
--- a/drivers/acpi/nfit/intel.c
+++ b/drivers/acpi/nfit/intel.c
@@ -3,6 +3,7 @@
 #include <linux/libnvdimm.h>
 #include <linux/ndctl.h>
 #include <linux/acpi.h>
+#include <asm/smp.h>
 #include "intel.h"
 #include "nfit.h"
 
@@ -75,8 +76,116 @@ static int intel_security_freeze(struct nvdimm *nvdimm)
 	return 0;
 }
 
+static int intel_security_change_key(struct nvdimm *nvdimm,
+		const struct nvdimm_key_data *old_data,
+		const struct nvdimm_key_data *new_data)
+{
+	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
+	struct {
+		struct nd_cmd_pkg pkg;
+		struct nd_intel_set_passphrase cmd;
+	} nd_cmd = {
+		.pkg = {
+			.nd_command = NVDIMM_INTEL_SET_PASSPHRASE,
+			.nd_family = NVDIMM_FAMILY_INTEL,
+			.nd_size_in = ND_INTEL_PASSPHRASE_SIZE * 2,
+			.nd_size_out = ND_INTEL_STATUS_SIZE,
+			.nd_fw_size = ND_INTEL_STATUS_SIZE,
+		},
+	};
+	int rc;
+
+	if (!test_bit(NVDIMM_INTEL_SET_PASSPHRASE, &nfit_mem->dsm_mask))
+		return -ENOTTY;
+
+	if (old_data)
+		memcpy(nd_cmd.cmd.old_pass, old_data->data,
+				sizeof(nd_cmd.cmd.old_pass));
+	memcpy(nd_cmd.cmd.new_pass, new_data->data,
+			sizeof(nd_cmd.cmd.new_pass));
+	rc = nvdimm_ctl(nvdimm, ND_CMD_CALL, &nd_cmd, sizeof(nd_cmd), NULL);
+	if (rc < 0)
+		return rc;
+
+	switch (nd_cmd.cmd.status) {
+	case 0:
+		return 0;
+	case ND_INTEL_STATUS_INVALID_PASS:
+		return -EINVAL;
+	case ND_INTEL_STATUS_NOT_SUPPORTED:
+		return -EOPNOTSUPP;
+	case ND_INTEL_STATUS_INVALID_STATE:
+	default:
+		return -EIO;
+	}
+}
+
+static void nvdimm_invalidate_cache(void);
+
+static int intel_security_unlock(struct nvdimm *nvdimm,
+		const struct nvdimm_key_data *key_data)
+{
+	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
+	struct {
+		struct nd_cmd_pkg pkg;
+		struct nd_intel_unlock_unit cmd;
+	} nd_cmd = {
+		.pkg = {
+			.nd_command = NVDIMM_INTEL_UNLOCK_UNIT,
+			.nd_family = NVDIMM_FAMILY_INTEL,
+			.nd_size_in = ND_INTEL_PASSPHRASE_SIZE,
+			.nd_size_out = ND_INTEL_STATUS_SIZE,
+			.nd_fw_size = ND_INTEL_STATUS_SIZE,
+		},
+	};
+	int rc;
+
+	if (!test_bit(NVDIMM_INTEL_UNLOCK_UNIT, &nfit_mem->dsm_mask))
+		return -ENOTTY;
+
+	memcpy(nd_cmd.cmd.passphrase, key_data->data,
+			sizeof(nd_cmd.cmd.passphrase));
+	rc = nvdimm_ctl(nvdimm, ND_CMD_CALL, &nd_cmd, sizeof(nd_cmd), NULL);
+	if (rc < 0)
+		return rc;
+	switch (nd_cmd.cmd.status) {
+	case 0:
+		break;
+	case ND_INTEL_STATUS_INVALID_PASS:
+		return -EINVAL;
+	default:
+		return -EIO;
+	}
+
+	/* DIMM unlocked, invalidate all CPU caches before we read it */
+	nvdimm_invalidate_cache();
+
+	return 0;
+}
+
+/*
+ * TODO: define a cross arch wbinvd equivalent when/if
+ * NVDIMM_FAMILY_INTEL command support arrives on another arch.
+ */
+#ifdef CONFIG_X86
+static void nvdimm_invalidate_cache(void)
+{
+	wbinvd_on_all_cpus();
+}
+#else
+static void nvdimm_invalidate_cache(void)
+{
+	WARN_ON_ONCE("cache invalidation required after unlock\n");
+}
+#endif
+
 static const struct nvdimm_security_ops __intel_security_ops = {
 	.state = intel_security_state,
 	.freeze = intel_security_freeze,
+	.change_key = intel_security_change_key,
+#ifdef CONFIG_X86
+	.unlock = intel_security_unlock,
+#endif
 };
+
 const struct nvdimm_security_ops *intel_security_ops = &__intel_security_ops;