[PATCH 8/9] tee: optee: implement AVB named persistent values support

[Sascha Hauer <s.hauer@pengutronix.de>]

Android Verified Boot (AVB) 2.0 spec. revision 1.1 introduces support
for named persistent values that must be tamper evident and allows AVB
to store arbitrary key-value pairs.

While AVB itself is not implemented in barebox. this patch allows
barebox to access the persistent value store. This is useful on its
own and can also be used to test the RPMB access in barebox.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/tee/optee/Kconfig  |   9 +++
 drivers/tee/optee/Makefile |   1 +
 drivers/tee/optee/avb.c    | 189 +++++++++++++++++++++++++++++++++++++++++++++
 include/tee/avb.h          |   9 +++
 4 files changed, 208 insertions(+)

diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig
index 045be3cca4..805aba65ed 100644
--- a/drivers/tee/optee/Kconfig
+++ b/drivers/tee/optee/Kconfig
@@ -31,6 +31,15 @@ config OPTEE_DEVFS
 	  but it's useful for compiling libteeclient + optee_tests for
 	  use inside barebox to verify proper operation of CONFIG_OPTEE.
 
+config OPTEE_AVB_PERSISTENT_VALUES
+	bool "Android Verified Boot (AVB) persistent values support"
+	depends on OPTEE
+	help
+	  AVB 2.0 spec. revision 1.1 introduces support for named persistent values
+	  that must be tamper evident and allows AVB to store arbitrary key-value
+	  pairs. AVB itself is not implemented in barebox, but enabling this option
+	  allows barebox to use the AVB persistent value store.
+
 endif
 
 config OF_FIXUP_OPTEE
diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
index f68352aa4e..1fbeb39fb8 100644
--- a/drivers/tee/optee/Makefile
+++ b/drivers/tee/optee/Makefile
@@ -7,3 +7,4 @@ optee-objs += rpc.o
 optee-objs += device.o
 optee-objs += smc_abi.o
 obj-$(CONFIG_MCI_MMC_RPMB) += rpmb.o
+obj-$(CONFIG_OPTEE_AVB_PERSISTENT_VALUES) += avb.o
diff --git a/drivers/tee/optee/avb.c b/drivers/tee/optee/avb.c
new file mode 100644
index 0000000000..0adbee6258
--- /dev/null
+++ b/drivers/tee/optee/avb.c
@@ -0,0 +1,189 @@
+#include <linux/types.h>
+#include <tee/avb.h>
+#include <linux/tee_drv.h>
+
+#include "optee_private.h"
+
+#define TA_AVB_UUID UUID_INIT(0x023f8f1a, 0x292a, 0x432b, \
+                      0x8f, 0xc4, 0xde, 0x84, 0x71, 0x35, 0x80, 0x67)
+#define TEE_PARAM_ATTR_TYPE_MEMREF_INOUT       7       /* input and output */
+#define TA_AVB_CMD_READ_PERSIST_VALUE     4
+#define TEE_PARAM_ATTR_TYPE_MEMREF_INPUT       5
+#define TA_AVB_CMD_WRITE_PERSIST_VALUE    5
+
+static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+	if (ver->impl_id == TEE_IMPL_ID_OPTEE)
+		return 1;
+	else
+		return 0;
+}
+
+int avb_read_persistent_value(const char *name, size_t buffer_size,
+			      u8 *out_buffer, size_t *out_num_bytes_read)
+{
+	const uuid_t avb_uuid = TA_AVB_UUID;
+	int rc = 0;
+	struct tee_shm *shm_name;
+	struct tee_shm *shm_buf;
+	struct tee_param param[2];
+	size_t name_size = strlen(name) + 1;
+	struct tee_ioctl_open_session_arg sess_arg = {};
+	struct tee_context *ctx = NULL;
+	struct tee_ioctl_invoke_arg arg;
+
+	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
+	if (IS_ERR(ctx))
+		return -ENODEV;
+
+	export_uuid(sess_arg.uuid, &avb_uuid);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
+	sess_arg.num_params = 0;
+
+	rc = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {
+		pr_debug("%s device enumeration pseudo TA not found\n", __func__);
+		rc = 0;
+		goto out_ctx;
+	}
+
+	shm_name = tee_shm_alloc_kernel_buf(ctx, name_size);
+	if (IS_ERR(shm_name)) {
+		rc = -ENOMEM;
+		goto close_session;
+	}
+
+	shm_buf = tee_shm_alloc_kernel_buf(ctx, buffer_size);
+	if (IS_ERR(shm_buf)) {
+		rc = -ENOMEM;
+		goto free_name;
+	}
+
+	memcpy(shm_name->kaddr, name, name_size);
+
+	memset(param, 0, sizeof(param));
+	param[0].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT;
+	param[0].u.memref.shm = shm_name;
+	param[0].u.memref.size = name_size;
+	param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
+	param[1].u.memref.shm = shm_buf;
+	param[1].u.memref.size = buffer_size;
+
+	arg.func = TA_AVB_CMD_READ_PERSIST_VALUE;
+	arg.session = sess_arg.session;
+	arg.num_params = 2;
+
+	rc = tee_client_invoke_func(ctx, &arg, param);
+	if (rc)
+		goto out;
+	switch (arg.ret) {
+	case TEEC_SUCCESS:
+		rc = 0;
+		break;
+	case TEEC_ERROR_ITEM_NOT_FOUND:
+		rc = -ENOENT;
+		break;
+	default:
+		rc = -EINVAL;
+		break;
+	}
+	if (rc)
+		goto out;
+
+	if (param[1].u.memref.size > buffer_size) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	*out_num_bytes_read = param[1].u.memref.size;
+
+	memcpy(out_buffer, shm_buf->kaddr, *out_num_bytes_read);
+
+out:
+	tee_shm_free(shm_buf);
+free_name:
+	tee_shm_free(shm_name);
+close_session:
+	tee_client_close_session(ctx, sess_arg.session);
+out_ctx:
+	tee_client_close_context(ctx);
+
+	return rc;
+}
+
+int avb_write_persistent_value(const char *name, size_t value_size,
+			       const u8 *value)
+{
+	const uuid_t avb_uuid = TA_AVB_UUID;
+	int rc = 0;
+	struct tee_shm *shm_name;
+	struct tee_shm *shm_buf;
+	struct tee_param param[2];
+	struct tee_ioctl_open_session_arg sess_arg = {};
+	struct tee_context *ctx = NULL;
+	size_t name_size = strlen(name) + 1;
+	struct tee_ioctl_invoke_arg inv_arg;
+
+	if (!value_size)
+		return -EINVAL;
+
+	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
+	if (IS_ERR(ctx))
+		return -ENODEV;
+
+	export_uuid(sess_arg.uuid, &avb_uuid);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
+	sess_arg.num_params = 0;
+
+	rc = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {
+		pr_err("%s AVB TA not found\n", __func__);
+		goto out_ctx;
+	}
+
+	shm_name = tee_shm_alloc_kernel_buf(ctx, name_size);
+	if (IS_ERR(shm_name)) {
+		rc = -ENOMEM;
+		goto close_session;
+	}
+
+	shm_buf = tee_shm_alloc_kernel_buf(ctx, value_size);
+	if (IS_ERR(shm_buf)) {
+		rc = -ENOMEM;
+		goto free_name;
+	}
+
+	memcpy(shm_name->kaddr, name, name_size);
+	memcpy(shm_buf->kaddr, value, value_size);
+
+	memset(param, 0, sizeof(param));
+	param[0].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT;
+	param[0].u.memref.shm = shm_name;
+	param[0].u.memref.size = name_size;
+	param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT;
+	param[1].u.memref.shm = shm_buf;
+	param[1].u.memref.size = value_size;
+
+	inv_arg.func = TA_AVB_CMD_WRITE_PERSIST_VALUE;
+	inv_arg.session = sess_arg.session;
+	inv_arg.num_params = 2;
+
+	rc = tee_client_invoke_func(ctx, &inv_arg, param);
+	if (rc)
+		goto out;
+	if (inv_arg.ret) {
+		pr_err("invoke func failed with 0x%08x\n", inv_arg.ret);
+		rc = -EIO;
+	}
+
+out:
+	tee_shm_free(shm_buf);
+free_name:
+	tee_shm_free(shm_name);
+close_session:
+	tee_client_close_session(ctx, sess_arg.session);
+out_ctx:
+	tee_client_close_context(ctx);
+
+	return rc;
+}
diff --git a/include/tee/avb.h b/include/tee/avb.h
new file mode 100644
index 0000000000..3873b5c59b
--- /dev/null
+++ b/include/tee/avb.h
@@ -0,0 +1,9 @@
+#ifndef TEE_AVB_H
+#define TEE_AVB_H
+
+int avb_write_persistent_value(const char *name, size_t value_size,
+			       const u8 *value);
+int avb_read_persistent_value(const char *name, size_t buffer_size,
+			      u8 *out_buffer, size_t *out_num_bytes_read);
+
+#endif /* TEE_AVB_H */

-- 
2.39.5