[PATCH v7 06/11] char: rpmb: add RPMB simulation device

[Tomas Winkler]

The RPMB partition simulation device is a virtual device that
provides simulation of the RPMB protocol and use kernel memory
as storage.

Be aware it doesn't promise any real security. This driver is
suitable only for testing of the RPMB subsystem or RPMB
applications prior to RPMB key provisioning, as RPMB key
programming can be performed only once in the life time of the
storage device.

The module currently supports two configuration options via
module parameters
1. max_wr_blks: for specifying max blocks that can be written
in a single command
2. daunits:  used to set storage capacity in 128K units.

V2: remove .owner setting, it is set automatically
V3: 1. Add shutdown handler (similar to ufshcd)
    2. Commit message fix
V4: Use select RPMB in Kconfg to ensure valid configuration.
V5: Revamp the code using the sequence command.
V6: 1. Be more verbose about some errors, after all this is a testing
    module.
    2. Fix RPMB_READ_DATA:
       a. The number of blocks for eMMC request frame should be 0
       b. Fix missing return before bailing on error
       c. Copy all the frames back
    3. Fix RPMB_WRITE_DATA:
       a. Compute MAC on result packet
       b. Also address should be set in the result frame.
    4. Remove platform device
    5. Update the commit message
V7: Resend.

Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
---
 drivers/char/rpmb/Kconfig    |  17 +
 drivers/char/rpmb/Makefile   |   1 +
 drivers/char/rpmb/rpmb_sim.c | 744 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 762 insertions(+)
 create mode 100644 drivers/char/rpmb/rpmb_sim.c

diff --git a/drivers/char/rpmb/Kconfig b/drivers/char/rpmb/Kconfig
index 6794be9fcc5e..533d813e9ed5 100644
--- a/drivers/char/rpmb/Kconfig
+++ b/drivers/char/rpmb/Kconfig
@@ -13,3 +13,20 @@ config RPMB_INTF_DEV
 	help
 	  Say yes here if you want to access RPMB from user space
 	  via character device interface /dev/rpmb%d
+
+
+config RPMB_SIM
+	tristate "RPMB partition device simulator"
+	default n
+	select RPMB
+	select CRYPTO_SHA256
+	select CRYPTO_HMAC
+	help
+	  RPMB partition simulation device is a virtual device that
+	  provides simulation of the RPMB protocol and use kernel memory
+	  as storage.
+
+	  Be aware it doesn't promise any real security. This driver is
+	  suitable only for testing of the RPMB subsystem or RPMB applications
+	  prior to RPMB key provisioning.
+          Most people should say N here.
diff --git a/drivers/char/rpmb/Makefile b/drivers/char/rpmb/Makefile
index b5dc087b1299..81f924fd9a87 100644
--- a/drivers/char/rpmb/Makefile
+++ b/drivers/char/rpmb/Makefile
@@ -1,5 +1,6 @@
 obj-$(CONFIG_RPMB) += rpmb.o
 rpmb-objs += core.o
 rpmb-$(CONFIG_RPMB_INTF_DEV) += cdev.o
+obj-$(CONFIG_RPMB_SIM) += rpmb_sim.o
 
 ccflags-y += -D__CHECK_ENDIAN__
diff --git a/drivers/char/rpmb/rpmb_sim.c b/drivers/char/rpmb/rpmb_sim.c
new file mode 100644
index 000000000000..429a08bd67d7
--- /dev/null
+++ b/drivers/char/rpmb/rpmb_sim.c
@@ -0,0 +1,744 @@
+/******************************************************************************
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2016 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * The full GNU General Public License is included in this distribution
+ * in the file called LICENSE.GPL.
+ *
+ * Contact Information:
+ *	Intel Corporation.
+ *	linux-mei@xxxxxxxxxxxxxxx
+ *	http://www.intel.com
+ *
+ * BSD LICENSE
+ *
+ * Copyright(c) 2016 Intel Corporation. All rights reserved.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *  * Neither the name Intel Corporation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *****************************************************************************/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <crypto/hash.h>
+#include <linux/scatterlist.h>
+#include <linux/sizes.h>
+
+#include <linux/rpmb.h>
+
+static const char id[] = "RPMB:SIM";
+#define CAPACITY_UNIT SZ_128K
+#define CAPACITY_MIN  SZ_128K
+#define CAPACITY_MAX  SZ_16M
+#define BLK_UNIT      SZ_256
+
+static unsigned int max_wr_blks = 2;
+module_param(max_wr_blks, uint, 0644);
+MODULE_PARM_DESC(max_wr_blks, "max blocks that can be written in a single command (default: 2)");
+
+static unsigned int daunits = 1;
+module_param(daunits, uint, 0644);
+MODULE_PARM_DESC(daunits, "number of data area units of 128K (default: 1)");
+
+struct blk {
+	u8 data[BLK_UNIT];
+};
+
+/**
+ * struct rpmb_sim_dev
+ *
+ * @dev:  back pointer device
+ * @rdev: rpmb device
+ * @auth_key: Authentication key register which is used to authenticate
+ *            accesses when MAC is calculated;
+ * @auth_key_set: true if auth key was set
+ * @write_counter: Counter value for the total amount of successful
+ *             authenticated data write requests made by the host.
+ *             The initial value of this register after production is 00000000h.
+ *             The value will be incremented by one along with each successful
+ *             programming access. The value cannot be reset. After the counter
+ *             has reached the maximum value of FFFFFFFFh,
+ *             it will not be incremented anymore (overflow prevention)
+ * @hash_tfm:  hmac(sha256) tfm
+ *
+ * @res_frames: frame that holds the result of the last write operation
+ * @out_frames: next read operation result frames
+ * @out_frames_cnt: number of the output frames
+ *
+ * @capacity: size of the partition in bytes multiple of 128K
+ * @blkcnt:   block count
+ * @da:       data area in blocks
+ */
+struct rpmb_sim_dev {
+	struct device *dev;
+	struct rpmb_dev *rdev;
+	u8 auth_key[32];
+	bool auth_key_set;
+	u32 write_counter;
+	struct crypto_shash *hash_tfm;
+
+	struct rpmb_frame res_frames[1];
+	struct rpmb_frame *out_frames;
+	unsigned int out_frames_cnt;
+
+	size_t capacity;
+	size_t blkcnt;
+	struct blk *da;
+};
+
+static __be16 op_result(struct rpmb_sim_dev *rsdev, u16 result)
+{
+	if (!rsdev->auth_key_set)
+		return cpu_to_be16(RPMB_ERR_NO_KEY);
+
+	if (rsdev->write_counter == 0xFFFFFFFF)
+		result |=  RPMB_ERR_COUNTER_EXPIRED;
+
+	return cpu_to_be16(result);
+}
+
+static __be16 req_to_resp(u16 req)
+{
+	return cpu_to_be16(RPMB_REQ2RESP(req));
+}
+
+static int rpmb_sim_calc_hmac(struct rpmb_sim_dev *rsdev,
+			      struct rpmb_frame *frames,
+			      unsigned int blks, u8 *mac)
+{
+	SHASH_DESC_ON_STACK(desc, rsdev->hash_tfm);
+	int i;
+	int ret;
+
+	desc->tfm = rsdev->hash_tfm;
+	desc->flags = 0;
+
+	ret = crypto_shash_init(desc);
+	if (ret)
+		goto out;
+
+	for (i = 0; i < blks; i++) {
+		ret = crypto_shash_update(desc, frames[i].data, hmac_data_len);
+		if (ret)
+			goto out;
+	}
+	ret = crypto_shash_final(desc, mac);
+out:
+	if (ret)
+		dev_err(rsdev->dev, "digest error = %d", ret);
+
+	return ret;
+}
+
+static int rpmb_op_not_programmed(struct rpmb_sim_dev *rsdev, u16 req)
+{
+	struct rpmb_frame *res_frame = rsdev->res_frames;
+
+	res_frame->req_resp = req_to_resp(req);
+	res_frame->result = op_result(rsdev, RPMB_ERR_NO_KEY);
+
+	dev_err(rsdev->dev, "not programmed\n");
+
+	return 0;
+}
+
+static int rpmb_op_program_key(struct rpmb_sim_dev *rsdev,
+			       struct rpmb_frame *in_frame, u32 cnt)
+{
+	struct rpmb_frame *res_frame = rsdev->res_frames;
+	u16 req;
+	int ret;
+	u16 err = RPMB_ERR_OK;
+
+	req = be16_to_cpu(in_frame[0].req_resp);
+
+	if (req != RPMB_PROGRAM_KEY)
+		return -EINVAL;
+
+	if (cnt != 1) {
+		dev_err(rsdev->dev, "wrong number of frames %d != 1\n", cnt);
+		return -EINVAL;
+	}
+
+	if (rsdev->auth_key_set) {
+		dev_err(rsdev->dev, "key allread set\n");
+		err = RPMB_ERR_WRITE;
+		goto out;
+	}
+
+	ret = crypto_shash_setkey(rsdev->hash_tfm, in_frame[0].key_mac, 32);
+	if (ret) {
+		dev_err(rsdev->dev, "set key failed = %d\n", ret);
+		err = RPMB_ERR_GENERAL;
+		goto out;
+	}
+
+	dev_dbg(rsdev->dev, "digest size %u\n",
+		crypto_shash_digestsize(rsdev->hash_tfm));
+
+	memcpy(rsdev->auth_key, in_frame[0].key_mac, 32);
+	rsdev->auth_key_set = true;
+out:
+
+	memset(res_frame, 0, sizeof(struct rpmb_frame));
+	res_frame->req_resp = req_to_resp(req);
+	res_frame->result = op_result(rsdev, err);
+
+	return 0;
+}
+
+static int rpmb_op_get_wr_counter(struct rpmb_sim_dev *rsdev,
+				  struct rpmb_frame *in_frame, u32 cnt)
+{
+	struct rpmb_frame *frame;
+	int ret = 0;
+	u16 req;
+	u16 err;
+
+	req = be16_to_cpu(in_frame[0].req_resp);
+	if (req != RPMB_GET_WRITE_COUNTER)
+		return -EINVAL;
+
+	if (cnt != 1) {
+		dev_err(rsdev->dev, "wrong number of frames %d != 1\n", cnt);
+		return -EINVAL;
+	}
+
+	frame = kcalloc(1, sizeof(struct rpmb_frame), GFP_KERNEL);
+	if (!frame) {
+		err = RPMB_ERR_READ;
+		ret = -ENOMEM;
+		rsdev->out_frames = rsdev->res_frames;
+		rsdev->out_frames_cnt = cnt;
+		goto out;
+	}
+
+	rsdev->out_frames = frame;
+	rsdev->out_frames_cnt = cnt;
+
+	frame->req_resp = req_to_resp(req);
+	frame->write_counter = cpu_to_be32(rsdev->write_counter);
+	memcpy(frame->nonce, in_frame[0].nonce, 16);
+
+	err = RPMB_ERR_OK;
+	if (rpmb_sim_calc_hmac(rsdev, frame, cnt, frame->key_mac))
+		err = RPMB_ERR_READ;
+
+out:
+	rsdev->out_frames[0].req_resp = req_to_resp(req);
+	rsdev->out_frames[0].result = op_result(rsdev, err);
+
+	return ret;
+}
+
+static int rpmb_op_write_data(struct rpmb_sim_dev *rsdev,
+			      struct rpmb_frame *in_frame, u32 cnt)
+{
+	struct rpmb_frame *res_frame = rsdev->res_frames;
+	u8 mac[32];
+	u16 req, err, addr, blks;
+	unsigned int i;
+	int ret = 0;
+
+	req = be16_to_cpu(in_frame[0].req_resp);
+	if (req != RPMB_WRITE_DATA)
+		return -EINVAL;
+
+	if (rsdev->write_counter == 0xFFFFFFFF) {
+		err = RPMB_ERR_WRITE;
+		goto out;
+	}
+
+	blks = be16_to_cpu(in_frame[0].block_count);
+	if (blks == 0 || blks > cnt) {
+		dev_err(rsdev->dev, "wrong number of frames %u > %u\n",
+			blks, cnt);
+		ret = -EINVAL;
+		err = RPMB_ERR_GENERAL;
+		goto out;
+	}
+
+	if (blks > max_wr_blks) {
+		err = RPMB_ERR_WRITE;
+		goto out;
+	}
+
+	addr = be16_to_cpu(in_frame[0].addr);
+	if (addr >= rsdev->blkcnt) {
+		err = RPMB_ERR_ADDRESS;
+		goto out;
+	}
+
+	if (rpmb_sim_calc_hmac(rsdev, in_frame, blks, mac)) {
+		err = RPMB_ERR_AUTH;
+		goto out;
+	}
+
+	/* mac is in the last frame */
+	if (memcmp(mac, in_frame[blks - 1].key_mac, sizeof(mac)) != 0) {
+		err = RPMB_ERR_AUTH;
+		goto out;
+	}
+
+	if (be32_to_cpu(in_frame[0].write_counter) != rsdev->write_counter) {
+		err = RPMB_ERR_COUNTER;
+		goto out;
+	}
+
+	if (addr + blks > rsdev->blkcnt) {
+		err = RPMB_ERR_WRITE;
+		goto out;
+	}
+
+	dev_dbg(rsdev->dev, "Writing = %u blokcs at addr = 0x%X\n", blks, addr);
+	err = RPMB_ERR_OK;
+	for (i = 0; i < blks; i++)
+		memcpy(rsdev->da[addr + i].data, in_frame[i].data, BLK_UNIT);
+
+	rsdev->write_counter++;
+
+	memset(res_frame, 0, sizeof(struct rpmb_frame));
+	res_frame->req_resp = req_to_resp(req);
+	res_frame->write_counter = cpu_to_be32(rsdev->write_counter);
+	res_frame->addr = cpu_to_be16(addr);
+	if (rpmb_sim_calc_hmac(rsdev, res_frame, 1, res_frame->key_mac))
+		err = RPMB_ERR_READ;
+
+out:
+	if (err != RPMB_ERR_OK) {
+		memset(res_frame, 0, sizeof(struct rpmb_frame));
+		res_frame->req_resp = req_to_resp(req);
+	}
+	res_frame->result = op_result(rsdev, err);
+
+	return ret;
+}
+
+static int rpmb_do_read_data(struct rpmb_sim_dev *rsdev,
+			     struct rpmb_frame *in_frame, u32 cnt)
+{
+	struct rpmb_frame *res_frame = rsdev->res_frames;
+	struct rpmb_frame *out_frames = NULL;
+	u8 mac[32];
+	u16 req, err, addr, blks;
+	unsigned int i;
+	int ret;
+
+	req = be16_to_cpu(in_frame->req_resp);
+	if (req != RPMB_READ_DATA)
+		return -EINVAL;
+
+	/* eMMc intentially set 0 here */
+	blks = be16_to_cpu(in_frame->block_count);
+	blks = blks ?: cnt;
+	if (blks > cnt) {
+		dev_err(rsdev->dev, "wrong number of frames cnt %u\n", blks);
+		ret = -EINVAL;
+		err = RPMB_ERR_GENERAL;
+		goto out;
+	}
+
+	out_frames = kcalloc(blks, sizeof(struct rpmb_frame), GFP_KERNEL);
+	if (!out_frames) {
+		ret = -ENOMEM;
+		err = RPMB_ERR_READ;
+		goto out;
+	}
+
+	ret = 0;
+	addr = be16_to_cpu(in_frame[0].addr);
+	if (addr >= rsdev->blkcnt) {
+		err = RPMB_ERR_ADDRESS;
+		goto out;
+	}
+
+	if (addr + blks > rsdev->blkcnt) {
+		err = RPMB_ERR_READ;
+		goto out;
+	}
+
+	dev_dbg(rsdev->dev, "reading = %u blokcs at addr = 0x%X\n", blks, addr);
+	for (i = 0; i < blks; i++) {
+		memcpy(out_frames[i].data, rsdev->da[addr + i].data, BLK_UNIT);
+		memcpy(out_frames[i].nonce, in_frame[0].nonce, 16);
+		out_frames[i].req_resp = req_to_resp(req);
+		out_frames[i].addr = in_frame[0].addr;
+		out_frames[i].block_count = cpu_to_be16(blks);
+	}
+
+	if (rpmb_sim_calc_hmac(rsdev, out_frames, blks, mac)) {
+		err = RPMB_ERR_AUTH;
+		goto out;
+	}
+
+	memcpy(out_frames[blks - 1].key_mac, mac, sizeof(mac));
+
+	err = RPMB_ERR_OK;
+	for (i = 0; i < blks; i++)
+		out_frames[i].result = op_result(rsdev, err);
+
+	rsdev->out_frames = out_frames;
+	rsdev->out_frames_cnt = cnt;
+
+	return 0;
+
+out:
+	memset(res_frame, 0, sizeof(struct rpmb_frame));
+	res_frame->req_resp = req_to_resp(req);
+	res_frame->result = op_result(rsdev, err);
+	kfree(out_frames);
+	rsdev->out_frames = res_frame;
+	rsdev->out_frames_cnt = 1;
+
+	return ret;
+}
+
+static int rpmb_op_read_data(struct rpmb_sim_dev *rsdev,
+			     struct rpmb_frame *in_frame, u32 cnt)
+{
+	struct rpmb_frame *res_frame = rsdev->res_frames;
+	u16 req;
+
+	req = be16_to_cpu(in_frame->req_resp);
+	if (req != RPMB_READ_DATA)
+		return -EINVAL;
+
+	memcpy(res_frame, in_frame, sizeof(*res_frame));
+
+	rsdev->out_frames = res_frame;
+	rsdev->out_frames_cnt = 1;
+
+	return 0;
+}
+
+static int rpmb_op_result_read(struct rpmb_sim_dev *rsdev,
+			       struct rpmb_frame *frames, u32 cnt)
+{
+	u16 req = be16_to_cpu(frames[0].req_resp);
+	u16 blks = be16_to_cpu(frames[0].block_count);
+
+	if (req != RPMB_RESULT_READ)
+		return -EINVAL;
+
+	if (blks != 0) {
+		dev_err(rsdev->dev, "wrong number of frames %u != 0\n",  blks);
+		return -EINVAL;
+	}
+
+	rsdev->out_frames = rsdev->res_frames;
+	rsdev->out_frames_cnt = 1;
+	return 0;
+}
+
+static int rpmb_sim_write(struct rpmb_sim_dev *rsdev,
+			  struct rpmb_frame *frames, u32 cnt)
+{
+	u16 req;
+	int ret;
+
+	if (!frames || !cnt)
+		return -EINVAL;
+
+	req = be16_to_cpu(frames[0].req_resp);
+	if (!rsdev->auth_key_set && req != RPMB_PROGRAM_KEY)
+		return rpmb_op_not_programmed(rsdev, req);
+
+	switch (req) {
+	case RPMB_PROGRAM_KEY:
+		dev_dbg(rsdev->dev, "rpmb: program key\n");
+		ret = rpmb_op_program_key(rsdev, frames, cnt);
+		break;
+	case RPMB_WRITE_DATA:
+		dev_dbg(rsdev->dev, "rpmb: write data\n");
+		ret = rpmb_op_write_data(rsdev, frames, cnt);
+		break;
+	case RPMB_GET_WRITE_COUNTER:
+		dev_dbg(rsdev->dev, "rpmb: get write counter\n");
+		ret = rpmb_op_get_wr_counter(rsdev, frames, cnt);
+		break;
+	case RPMB_READ_DATA:
+		dev_dbg(rsdev->dev, "rpmb: read data\n");
+		ret = rpmb_op_read_data(rsdev, frames, cnt);
+		break;
+	case RPMB_RESULT_READ:
+		dev_dbg(rsdev->dev, "rpmb: result read\n");
+		ret = rpmb_op_result_read(rsdev, frames, cnt);
+		break;
+	default:
+		dev_err(rsdev->dev, "unsupported command %u\n", req);
+		ret = -EINVAL;
+		break;
+	}
+
+	dev_dbg(rsdev->dev, "rpmb: ret=%d\n", ret);
+
+	return ret;
+}
+
+static int rpmb_sim_read(struct rpmb_sim_dev *rsdev,
+			 struct rpmb_frame *frames, u32 cnt)
+{
+	int i;
+
+	if (!frames || !cnt)
+		return -EINVAL;
+
+	if (!rsdev->out_frames || rsdev->out_frames_cnt == 0) {
+		dev_err(rsdev->dev, "out_frames are not set\n");
+		return -EINVAL;
+	}
+
+	if (rsdev->out_frames->req_resp == cpu_to_be16(RPMB_READ_DATA))
+		rpmb_do_read_data(rsdev, rsdev->out_frames, cnt);
+
+	for (i = 0; i < min_t(u32, rsdev->out_frames_cnt, cnt); i++)
+		memcpy(&frames[i], &rsdev->out_frames[i], sizeof(frames[i]));
+
+	if (rsdev->out_frames != rsdev->res_frames)
+		kfree(rsdev->out_frames);
+
+	rsdev->out_frames = NULL;
+	rsdev->out_frames_cnt = 0;
+	dev_dbg(rsdev->dev, "rpmb: cnt=%d\n", cnt);
+
+	return 0;
+}
+
+static int rpmb_sim_cmd_seq(struct device *dev,
+			    struct rpmb_cmd *cmds, u32 ncmds)
+{
+	struct rpmb_sim_dev *rsdev;
+	int i;
+	int ret;
+	struct rpmb_cmd *cmd;
+
+	if (!dev)
+		return -EINVAL;
+
+	dev_err(dev, "rpmb_cmd_seq\n");
+
+	rsdev = dev_get_drvdata(dev);
+
+	if (!rsdev)
+		return -EINVAL;
+
+	for (ret = 0, i = 0; i < ncmds && !ret; i++) {
+		cmd = &cmds[i];
+		if (cmd->flags & RPMB_F_WRITE)
+			ret = rpmb_sim_write(rsdev, cmd->frames, cmd->nframes);
+		else
+			ret = rpmb_sim_read(rsdev, cmd->frames, cmd->nframes);
+	}
+	return ret;
+}
+
+static struct rpmb_ops rpmb_sim_ops = {
+	.cmd_seq = rpmb_sim_cmd_seq,
+	.type = RPMB_TYPE_EMMC,
+};
+
+static int rpmb_sim_hmac_256_alloc(struct rpmb_sim_dev *rsdev)
+{
+	struct crypto_shash *hash_tfm;
+
+	hash_tfm = crypto_alloc_shash("hmac(sha256)", 0, 0);
+	if (IS_ERR(hash_tfm))
+		return PTR_ERR(hash_tfm);
+
+	rsdev->hash_tfm = hash_tfm;
+
+	dev_dbg(rsdev->dev, "hamac(sha256) registered\n");
+	return 0;
+}
+
+static void rpmb_sim_hmac_256_free(struct rpmb_sim_dev *rsdev)
+{
+	if (rsdev->hash_tfm)
+		crypto_free_shash(rsdev->hash_tfm);
+
+	rsdev->hash_tfm = NULL;
+}
+
+static int rpmb_sim_probe(struct device *dev)
+{
+	struct rpmb_sim_dev *rsdev;
+	int ret;
+
+	rsdev = kzalloc(sizeof(*rsdev), GFP_KERNEL);
+	if (!rsdev)
+		return -ENOMEM;
+
+	rsdev->dev = dev;
+
+	ret = rpmb_sim_hmac_256_alloc(rsdev);
+	if (ret)
+		goto err;
+
+	rsdev->capacity = CAPACITY_UNIT * daunits;
+	rsdev->blkcnt  = rsdev->capacity / BLK_UNIT;
+	rsdev->da = kzalloc(rsdev->capacity, GFP_KERNEL);
+	if (!rsdev->da) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	rpmb_sim_ops.dev_id_len = strlen(id);
+	rpmb_sim_ops.dev_id = id;
+	rpmb_sim_ops.reliable_wr_cnt = max_wr_blks;
+
+	rsdev->rdev = rpmb_dev_register(rsdev->dev, &rpmb_sim_ops);
+	if (IS_ERR(rsdev->rdev)) {
+		ret = PTR_ERR(rsdev->rdev);
+		goto err;
+	}
+
+	dev_info(dev, "registered RPMB capacity = %zu of %zu blocks\n",
+		 rsdev->capacity, rsdev->blkcnt);
+
+	dev_set_drvdata(dev, rsdev);
+
+	return 0;
+err:
+	rpmb_sim_hmac_256_free(rsdev);
+	if (rsdev)
+		kfree(rsdev->da);
+	kfree(rsdev);
+	return ret;
+}
+
+static int rpmb_sim_remove(struct device *dev)
+{
+	struct rpmb_sim_dev *rsdev;
+
+	rsdev = dev_get_drvdata(dev);
+
+	rpmb_dev_unregister(rsdev->dev);
+
+	dev_set_drvdata(dev, NULL);
+
+	rpmb_sim_hmac_256_free(rsdev);
+
+	kfree(rsdev->da);
+	kfree(rsdev);
+	return 0;
+}
+
+static void rpmb_sim_shutdown(struct device *dev)
+{
+	rpmb_sim_remove(dev);
+}
+
+static int rpmb_sim_match(struct device *dev, struct device_driver *drv)
+{
+	return 1;
+}
+
+static struct bus_type rpmb_sim_bus = {
+	.name = "rpmb_sim",
+	.match = rpmb_sim_match,
+};
+
+static struct device_driver rpmb_sim_drv = {
+	.name  = "rpmb_sim",
+	.probe = rpmb_sim_probe,
+	.remove = rpmb_sim_remove,
+	.shutdown = rpmb_sim_shutdown,
+};
+
+static void rpmb_sim_dev_release(struct device *dev)
+{
+}
+
+static struct device rpmb_sim_dev;
+
+static int __init rpmb_sim_init(void)
+{
+	int ret;
+	struct device *dev = &rpmb_sim_dev;
+	struct device_driver *drv = &rpmb_sim_drv;
+
+	ret = bus_register(&rpmb_sim_bus);
+	if (ret)
+		return ret;
+
+	dev->bus = &rpmb_sim_bus;
+	dev->release = rpmb_sim_dev_release;
+	dev_set_name(dev, "%s", "rpmb_sim");
+	ret = device_register(dev);
+	if (ret) {
+		pr_err("device register failed %d\n", ret);
+		goto err_device;
+	}
+
+	drv->bus = &rpmb_sim_bus;
+	ret = driver_register(drv);
+	if (ret) {
+		pr_err("driver register failed %d\n", ret);
+		goto err_driver;
+	}
+
+	return 0;
+
+err_driver:
+	device_unregister(dev);
+err_device:
+	bus_unregister(&rpmb_sim_bus);
+	return ret;
+}
+
+static void __exit rpmb_sim_exit(void)
+{
+	struct device *dev = &rpmb_sim_dev;
+	struct device_driver *drv = &rpmb_sim_drv;
+
+	device_unregister(dev);
+	driver_unregister(drv);
+	bus_unregister(&rpmb_sim_bus);
+}
+
+module_init(rpmb_sim_init);
+module_exit(rpmb_sim_exit);
+
+MODULE_AUTHOR("Tomas Winkler <tomas.winkler@xxxxxxxxx");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("rpmb_sim:rpmb_sim");
-- 
2.7.4