linuxdebug/drivers/firmware/turris-mox-rwtm.c

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2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: GPL-2.0
/*
* Turris Mox rWTM firmware driver
*
* Copyright (C) 2019 Marek Behún <kabel@kernel.org>
*/
#include <linux/armada-37xx-rwtm-mailbox.h>
#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/hw_random.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#define DRIVER_NAME "turris-mox-rwtm"
/*
* The macros and constants below come from Turris Mox's rWTM firmware code.
* This firmware is open source and it's sources can be found at
* https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
*/
#define MBOX_STS_SUCCESS (0 << 30)
#define MBOX_STS_FAIL (1 << 30)
#define MBOX_STS_BADCMD (2 << 30)
#define MBOX_STS_ERROR(s) ((s) & (3 << 30))
#define MBOX_STS_VALUE(s) (((s) >> 10) & 0xfffff)
#define MBOX_STS_CMD(s) ((s) & 0x3ff)
enum mbox_cmd {
MBOX_CMD_GET_RANDOM = 1,
MBOX_CMD_BOARD_INFO = 2,
MBOX_CMD_ECDSA_PUB_KEY = 3,
MBOX_CMD_HASH = 4,
MBOX_CMD_SIGN = 5,
MBOX_CMD_VERIFY = 6,
MBOX_CMD_OTP_READ = 7,
MBOX_CMD_OTP_WRITE = 8,
};
struct mox_kobject;
struct mox_rwtm {
struct device *dev;
struct mbox_client mbox_client;
struct mbox_chan *mbox;
struct mox_kobject *kobj;
struct hwrng hwrng;
struct armada_37xx_rwtm_rx_msg reply;
void *buf;
dma_addr_t buf_phys;
struct mutex busy;
struct completion cmd_done;
/* board information */
int has_board_info;
u64 serial_number;
int board_version, ram_size;
u8 mac_address1[6], mac_address2[6];
/* public key burned in eFuse */
int has_pubkey;
u8 pubkey[135];
#ifdef CONFIG_DEBUG_FS
/*
* Signature process. This is currently done via debugfs, because it
* does not conform to the sysfs standard "one file per attribute".
* It should be rewritten via crypto API once akcipher API is available
* from userspace.
*/
struct dentry *debugfs_root;
u32 last_sig[34];
int last_sig_done;
#endif
};
struct mox_kobject {
struct kobject kobj;
struct mox_rwtm *rwtm;
};
static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
{
return &rwtm->kobj->kobj;
}
static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
{
return container_of(kobj, struct mox_kobject, kobj)->rwtm;
}
static void mox_kobj_release(struct kobject *kobj)
{
kfree(to_rwtm(kobj)->kobj);
}
static struct kobj_type mox_kobj_ktype = {
.release = mox_kobj_release,
.sysfs_ops = &kobj_sysfs_ops,
};
static int mox_kobj_create(struct mox_rwtm *rwtm)
{
rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
if (!rwtm->kobj)
return -ENOMEM;
kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
kobject_put(rwtm_to_kobj(rwtm));
return -ENXIO;
}
rwtm->kobj->rwtm = rwtm;
return 0;
}
#define MOX_ATTR_RO(name, format, cat) \
static ssize_t \
name##_show(struct kobject *kobj, struct kobj_attribute *a, \
char *buf) \
{ \
struct mox_rwtm *rwtm = to_rwtm(kobj); \
if (!rwtm->has_##cat) \
return -ENODATA; \
return sprintf(buf, format, rwtm->name); \
} \
static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)
MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
MOX_ATTR_RO(board_version, "%i\n", board_info);
MOX_ATTR_RO(ram_size, "%i\n", board_info);
MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
MOX_ATTR_RO(pubkey, "%s\n", pubkey);
static int mox_get_status(enum mbox_cmd cmd, u32 retval)
{
if (MBOX_STS_CMD(retval) != cmd)
return -EIO;
else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
return -(int)MBOX_STS_VALUE(retval);
else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
return -ENOSYS;
else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
return -EIO;
else
return MBOX_STS_VALUE(retval);
}
static const struct attribute *mox_rwtm_attrs[] = {
&mox_attr_serial_number.attr,
&mox_attr_board_version.attr,
&mox_attr_ram_size.attr,
&mox_attr_mac_address1.attr,
&mox_attr_mac_address2.attr,
&mox_attr_pubkey.attr,
NULL
};
static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
{
struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
struct armada_37xx_rwtm_rx_msg *msg = data;
rwtm->reply = *msg;
complete(&rwtm->cmd_done);
}
static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
{
mac[0] = t1 >> 8;
mac[1] = t1;
mac[2] = t2 >> 24;
mac[3] = t2 >> 16;
mac[4] = t2 >> 8;
mac[5] = t2;
}
static int mox_get_board_info(struct mox_rwtm *rwtm)
{
struct armada_37xx_rwtm_tx_msg msg;
struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
int ret;
msg.command = MBOX_CMD_BOARD_INFO;
ret = mbox_send_message(rwtm->mbox, &msg);
if (ret < 0)
return ret;
ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
if (ret < 0)
return ret;
ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
if (ret == -ENODATA) {
dev_warn(rwtm->dev,
"Board does not have manufacturing information burned!\n");
} else if (ret == -ENOSYS) {
dev_notice(rwtm->dev,
"Firmware does not support the BOARD_INFO command\n");
} else if (ret < 0) {
return ret;
} else {
rwtm->serial_number = reply->status[1];
rwtm->serial_number <<= 32;
rwtm->serial_number |= reply->status[0];
rwtm->board_version = reply->status[2];
rwtm->ram_size = reply->status[3];
reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
reply->status[5]);
reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
reply->status[7]);
rwtm->has_board_info = 1;
pr_info("Turris Mox serial number %016llX\n",
rwtm->serial_number);
pr_info(" board version %i\n", rwtm->board_version);
pr_info(" burned RAM size %i MiB\n", rwtm->ram_size);
}
msg.command = MBOX_CMD_ECDSA_PUB_KEY;
ret = mbox_send_message(rwtm->mbox, &msg);
if (ret < 0)
return ret;
ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
if (ret < 0)
return ret;
ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
if (ret == -ENODATA) {
dev_warn(rwtm->dev, "Board has no public key burned!\n");
} else if (ret == -ENOSYS) {
dev_notice(rwtm->dev,
"Firmware does not support the ECDSA_PUB_KEY command\n");
} else if (ret < 0) {
return ret;
} else {
u32 *s = reply->status;
rwtm->has_pubkey = 1;
sprintf(rwtm->pubkey,
"%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
}
return 0;
}
static int check_get_random_support(struct mox_rwtm *rwtm)
{
struct armada_37xx_rwtm_tx_msg msg;
int ret;
msg.command = MBOX_CMD_GET_RANDOM;
msg.args[0] = 1;
msg.args[1] = rwtm->buf_phys;
msg.args[2] = 4;
ret = mbox_send_message(rwtm->mbox, &msg);
if (ret < 0)
return ret;
ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
if (ret < 0)
return ret;
return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
}
static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
struct armada_37xx_rwtm_tx_msg msg;
int ret;
if (max > 4096)
max = 4096;
msg.command = MBOX_CMD_GET_RANDOM;
msg.args[0] = 1;
msg.args[1] = rwtm->buf_phys;
msg.args[2] = (max + 3) & ~3;
if (!wait) {
if (!mutex_trylock(&rwtm->busy))
return -EBUSY;
} else {
mutex_lock(&rwtm->busy);
}
ret = mbox_send_message(rwtm->mbox, &msg);
if (ret < 0)
goto unlock_mutex;
ret = wait_for_completion_interruptible(&rwtm->cmd_done);
if (ret < 0)
goto unlock_mutex;
ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
if (ret < 0)
goto unlock_mutex;
memcpy(data, rwtm->buf, max);
ret = max;
unlock_mutex:
mutex_unlock(&rwtm->busy);
return ret;
}
#ifdef CONFIG_DEBUG_FS
static int rwtm_debug_open(struct inode *inode, struct file *file)
{
file->private_data = inode->i_private;
return nonseekable_open(inode, file);
}
static ssize_t do_sign_read(struct file *file, char __user *buf, size_t len,
loff_t *ppos)
{
struct mox_rwtm *rwtm = file->private_data;
ssize_t ret;
/* only allow one read, of 136 bytes, from position 0 */
if (*ppos != 0)
return 0;
if (len < 136)
return -EINVAL;
if (!rwtm->last_sig_done)
return -ENODATA;
/* 2 arrays of 17 32-bit words are 136 bytes */
ret = simple_read_from_buffer(buf, len, ppos, rwtm->last_sig, 136);
rwtm->last_sig_done = 0;
return ret;
}
static ssize_t do_sign_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
struct mox_rwtm *rwtm = file->private_data;
struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
struct armada_37xx_rwtm_tx_msg msg;
loff_t dummy = 0;
ssize_t ret;
/* the input is a SHA-512 hash, so exactly 64 bytes have to be read */
if (len != 64)
return -EINVAL;
/* if last result is not zero user has not read that information yet */
if (rwtm->last_sig_done)
return -EBUSY;
if (!mutex_trylock(&rwtm->busy))
return -EBUSY;
/*
* Here we have to send:
* 1. Address of the input to sign.
* The input is an array of 17 32-bit words, the first (most
* significat) is 0, the rest 16 words are copied from the SHA-512
* hash given by the user and converted from BE to LE.
* 2. Address of the buffer where ECDSA signature value R shall be
* stored by the rWTM firmware.
* 3. Address of the buffer where ECDSA signature value S shall be
* stored by the rWTM firmware.
*/
memset(rwtm->buf, 0, 4);
ret = simple_write_to_buffer(rwtm->buf + 4, 64, &dummy, buf, len);
if (ret < 0)
goto unlock_mutex;
be32_to_cpu_array(rwtm->buf, rwtm->buf, 17);
msg.command = MBOX_CMD_SIGN;
msg.args[0] = 1;
msg.args[1] = rwtm->buf_phys;
msg.args[2] = rwtm->buf_phys + 68;
msg.args[3] = rwtm->buf_phys + 2 * 68;
ret = mbox_send_message(rwtm->mbox, &msg);
if (ret < 0)
goto unlock_mutex;
ret = wait_for_completion_interruptible(&rwtm->cmd_done);
if (ret < 0)
goto unlock_mutex;
ret = MBOX_STS_VALUE(reply->retval);
if (MBOX_STS_ERROR(reply->retval) != MBOX_STS_SUCCESS)
goto unlock_mutex;
/*
* Here we read the R and S values of the ECDSA signature
* computed by the rWTM firmware and convert their words from
* LE to BE.
*/
memcpy(rwtm->last_sig, rwtm->buf + 68, 136);
cpu_to_be32_array(rwtm->last_sig, rwtm->last_sig, 34);
rwtm->last_sig_done = 1;
mutex_unlock(&rwtm->busy);
return len;
unlock_mutex:
mutex_unlock(&rwtm->busy);
return ret;
}
static const struct file_operations do_sign_fops = {
.owner = THIS_MODULE,
.open = rwtm_debug_open,
.read = do_sign_read,
.write = do_sign_write,
.llseek = no_llseek,
};
static int rwtm_register_debugfs(struct mox_rwtm *rwtm)
{
struct dentry *root, *entry;
root = debugfs_create_dir("turris-mox-rwtm", NULL);
if (IS_ERR(root))
return PTR_ERR(root);
entry = debugfs_create_file_unsafe("do_sign", 0600, root, rwtm,
&do_sign_fops);
if (IS_ERR(entry))
goto err_remove;
rwtm->debugfs_root = root;
return 0;
err_remove:
debugfs_remove_recursive(root);
return PTR_ERR(entry);
}
static void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
{
debugfs_remove_recursive(rwtm->debugfs_root);
}
#else
static inline int rwtm_register_debugfs(struct mox_rwtm *rwtm)
{
return 0;
}
static inline void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
{
}
#endif
static int turris_mox_rwtm_probe(struct platform_device *pdev)
{
struct mox_rwtm *rwtm;
struct device *dev = &pdev->dev;
int ret;
rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
if (!rwtm)
return -ENOMEM;
rwtm->dev = dev;
rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
GFP_KERNEL);
if (!rwtm->buf)
return -ENOMEM;
ret = mox_kobj_create(rwtm);
if (ret < 0) {
dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
return ret;
}
ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
if (ret < 0) {
dev_err(dev, "Cannot create sysfs files!\n");
goto put_kobj;
}
platform_set_drvdata(pdev, rwtm);
mutex_init(&rwtm->busy);
rwtm->mbox_client.dev = dev;
rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;
rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
if (IS_ERR(rwtm->mbox)) {
ret = PTR_ERR(rwtm->mbox);
if (ret != -EPROBE_DEFER)
dev_err(dev, "Cannot request mailbox channel: %i\n",
ret);
goto remove_files;
}
init_completion(&rwtm->cmd_done);
ret = mox_get_board_info(rwtm);
if (ret < 0)
dev_warn(dev, "Cannot read board information: %i\n", ret);
ret = check_get_random_support(rwtm);
if (ret < 0) {
dev_notice(dev,
"Firmware does not support the GET_RANDOM command\n");
goto free_channel;
}
rwtm->hwrng.name = DRIVER_NAME "_hwrng";
rwtm->hwrng.read = mox_hwrng_read;
rwtm->hwrng.priv = (unsigned long) rwtm;
rwtm->hwrng.quality = 1024;
ret = devm_hwrng_register(dev, &rwtm->hwrng);
if (ret < 0) {
dev_err(dev, "Cannot register HWRNG: %i\n", ret);
goto free_channel;
}
ret = rwtm_register_debugfs(rwtm);
if (ret < 0) {
dev_err(dev, "Failed creating debugfs entries: %i\n", ret);
goto free_channel;
}
dev_info(dev, "HWRNG successfully registered\n");
return 0;
free_channel:
mbox_free_channel(rwtm->mbox);
remove_files:
sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
put_kobj:
kobject_put(rwtm_to_kobj(rwtm));
return ret;
}
static int turris_mox_rwtm_remove(struct platform_device *pdev)
{
struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
rwtm_unregister_debugfs(rwtm);
sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
kobject_put(rwtm_to_kobj(rwtm));
mbox_free_channel(rwtm->mbox);
return 0;
}
static const struct of_device_id turris_mox_rwtm_match[] = {
{ .compatible = "cznic,turris-mox-rwtm", },
{ .compatible = "marvell,armada-3700-rwtm-firmware", },
{ },
};
MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);
static struct platform_driver turris_mox_rwtm_driver = {
.probe = turris_mox_rwtm_probe,
.remove = turris_mox_rwtm_remove,
.driver = {
.name = DRIVER_NAME,
.of_match_table = turris_mox_rwtm_match,
},
};
module_platform_driver(turris_mox_rwtm_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");