1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Turris Mox rWTM firmware driver
4 *
5 * Copyright (C) 2019 Marek Behún <kabel@kernel.org>
6 */
7
8 #include <linux/armada-37xx-rwtm-mailbox.h>
9 #include <linux/completion.h>
10 #include <linux/debugfs.h>
11 #include <linux/dma-mapping.h>
12 #include <linux/hw_random.h>
13 #include <linux/mailbox_client.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/slab.h>
19
20 #define DRIVER_NAME "turris-mox-rwtm"
21
22 /*
23 * The macros and constants below come from Turris Mox's rWTM firmware code.
24 * This firmware is open source and it's sources can be found at
25 * https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
26 */
27
28 #define MBOX_STS_SUCCESS (0 << 30)
29 #define MBOX_STS_FAIL (1 << 30)
30 #define MBOX_STS_BADCMD (2 << 30)
31 #define MBOX_STS_ERROR(s) ((s) & (3 << 30))
32 #define MBOX_STS_VALUE(s) (((s) >> 10) & 0xfffff)
33 #define MBOX_STS_CMD(s) ((s) & 0x3ff)
34
35 enum mbox_cmd {
36 MBOX_CMD_GET_RANDOM = 1,
37 MBOX_CMD_BOARD_INFO = 2,
38 MBOX_CMD_ECDSA_PUB_KEY = 3,
39 MBOX_CMD_HASH = 4,
40 MBOX_CMD_SIGN = 5,
41 MBOX_CMD_VERIFY = 6,
42
43 MBOX_CMD_OTP_READ = 7,
44 MBOX_CMD_OTP_WRITE = 8,
45 };
46
47 struct mox_kobject;
48
49 struct mox_rwtm {
50 struct device *dev;
51 struct mbox_client mbox_client;
52 struct mbox_chan *mbox;
53 struct mox_kobject *kobj;
54 struct hwrng hwrng;
55
56 struct armada_37xx_rwtm_rx_msg reply;
57
58 void *buf;
59 dma_addr_t buf_phys;
60
61 struct mutex busy;
62 struct completion cmd_done;
63
64 /* board information */
65 int has_board_info;
66 u64 serial_number;
67 int board_version, ram_size;
68 u8 mac_address1[6], mac_address2[6];
69
70 /* public key burned in eFuse */
71 int has_pubkey;
72 u8 pubkey[135];
73
74 #ifdef CONFIG_DEBUG_FS
75 /*
76 * Signature process. This is currently done via debugfs, because it
77 * does not conform to the sysfs standard "one file per attribute".
78 * It should be rewritten via crypto API once akcipher API is available
79 * from userspace.
80 */
81 struct dentry *debugfs_root;
82 u32 last_sig[34];
83 int last_sig_done;
84 #endif
85 };
86
87 struct mox_kobject {
88 struct kobject kobj;
89 struct mox_rwtm *rwtm;
90 };
91
rwtm_to_kobj(struct mox_rwtm * rwtm)92 static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
93 {
94 return &rwtm->kobj->kobj;
95 }
96
to_rwtm(struct kobject * kobj)97 static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
98 {
99 return container_of(kobj, struct mox_kobject, kobj)->rwtm;
100 }
101
mox_kobj_release(struct kobject * kobj)102 static void mox_kobj_release(struct kobject *kobj)
103 {
104 kfree(to_rwtm(kobj)->kobj);
105 }
106
107 static struct kobj_type mox_kobj_ktype = {
108 .release = mox_kobj_release,
109 .sysfs_ops = &kobj_sysfs_ops,
110 };
111
mox_kobj_create(struct mox_rwtm * rwtm)112 static int mox_kobj_create(struct mox_rwtm *rwtm)
113 {
114 rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
115 if (!rwtm->kobj)
116 return -ENOMEM;
117
118 kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
119 if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
120 kobject_put(rwtm_to_kobj(rwtm));
121 return -ENXIO;
122 }
123
124 rwtm->kobj->rwtm = rwtm;
125
126 return 0;
127 }
128
129 #define MOX_ATTR_RO(name, format, cat) \
130 static ssize_t \
131 name##_show(struct kobject *kobj, struct kobj_attribute *a, \
132 char *buf) \
133 { \
134 struct mox_rwtm *rwtm = to_rwtm(kobj); \
135 if (!rwtm->has_##cat) \
136 return -ENODATA; \
137 return sprintf(buf, format, rwtm->name); \
138 } \
139 static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)
140
141 MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
142 MOX_ATTR_RO(board_version, "%i\n", board_info);
143 MOX_ATTR_RO(ram_size, "%i\n", board_info);
144 MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
145 MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
146 MOX_ATTR_RO(pubkey, "%s\n", pubkey);
147
mox_get_status(enum mbox_cmd cmd,u32 retval)148 static int mox_get_status(enum mbox_cmd cmd, u32 retval)
149 {
150 if (MBOX_STS_CMD(retval) != cmd ||
151 MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
152 return -EIO;
153 else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
154 return -(int)MBOX_STS_VALUE(retval);
155 else
156 return MBOX_STS_VALUE(retval);
157 }
158
159 static const struct attribute *mox_rwtm_attrs[] = {
160 &mox_attr_serial_number.attr,
161 &mox_attr_board_version.attr,
162 &mox_attr_ram_size.attr,
163 &mox_attr_mac_address1.attr,
164 &mox_attr_mac_address2.attr,
165 &mox_attr_pubkey.attr,
166 NULL
167 };
168
mox_rwtm_rx_callback(struct mbox_client * cl,void * data)169 static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
170 {
171 struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
172 struct armada_37xx_rwtm_rx_msg *msg = data;
173
174 rwtm->reply = *msg;
175 complete(&rwtm->cmd_done);
176 }
177
reply_to_mac_addr(u8 * mac,u32 t1,u32 t2)178 static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
179 {
180 mac[0] = t1 >> 8;
181 mac[1] = t1;
182 mac[2] = t2 >> 24;
183 mac[3] = t2 >> 16;
184 mac[4] = t2 >> 8;
185 mac[5] = t2;
186 }
187
mox_get_board_info(struct mox_rwtm * rwtm)188 static int mox_get_board_info(struct mox_rwtm *rwtm)
189 {
190 struct armada_37xx_rwtm_tx_msg msg;
191 struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
192 int ret;
193
194 msg.command = MBOX_CMD_BOARD_INFO;
195 ret = mbox_send_message(rwtm->mbox, &msg);
196 if (ret < 0)
197 return ret;
198
199 ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
200 if (ret < 0)
201 return ret;
202
203 ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
204 if (ret < 0 && ret != -ENODATA) {
205 return ret;
206 } else if (ret == -ENODATA) {
207 dev_warn(rwtm->dev,
208 "Board does not have manufacturing information burned!\n");
209 } else {
210 rwtm->serial_number = reply->status[1];
211 rwtm->serial_number <<= 32;
212 rwtm->serial_number |= reply->status[0];
213 rwtm->board_version = reply->status[2];
214 rwtm->ram_size = reply->status[3];
215 reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
216 reply->status[5]);
217 reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
218 reply->status[7]);
219 rwtm->has_board_info = 1;
220
221 pr_info("Turris Mox serial number %016llX\n",
222 rwtm->serial_number);
223 pr_info(" board version %i\n", rwtm->board_version);
224 pr_info(" burned RAM size %i MiB\n", rwtm->ram_size);
225 }
226
227 msg.command = MBOX_CMD_ECDSA_PUB_KEY;
228 ret = mbox_send_message(rwtm->mbox, &msg);
229 if (ret < 0)
230 return ret;
231
232 ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
233 if (ret < 0)
234 return ret;
235
236 ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
237 if (ret < 0 && ret != -ENODATA) {
238 return ret;
239 } else if (ret == -ENODATA) {
240 dev_warn(rwtm->dev, "Board has no public key burned!\n");
241 } else {
242 u32 *s = reply->status;
243
244 rwtm->has_pubkey = 1;
245 sprintf(rwtm->pubkey,
246 "%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
247 ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
248 s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
249 }
250
251 return 0;
252 }
253
mox_hwrng_read(struct hwrng * rng,void * data,size_t max,bool wait)254 static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
255 {
256 struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
257 struct armada_37xx_rwtm_tx_msg msg;
258 int ret;
259
260 if (max > 4096)
261 max = 4096;
262
263 msg.command = MBOX_CMD_GET_RANDOM;
264 msg.args[0] = 1;
265 msg.args[1] = rwtm->buf_phys;
266 msg.args[2] = (max + 3) & ~3;
267
268 if (!wait) {
269 if (!mutex_trylock(&rwtm->busy))
270 return -EBUSY;
271 } else {
272 mutex_lock(&rwtm->busy);
273 }
274
275 ret = mbox_send_message(rwtm->mbox, &msg);
276 if (ret < 0)
277 goto unlock_mutex;
278
279 ret = wait_for_completion_interruptible(&rwtm->cmd_done);
280 if (ret < 0)
281 goto unlock_mutex;
282
283 ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
284 if (ret < 0)
285 goto unlock_mutex;
286
287 memcpy(data, rwtm->buf, max);
288 ret = max;
289
290 unlock_mutex:
291 mutex_unlock(&rwtm->busy);
292 return ret;
293 }
294
295 #ifdef CONFIG_DEBUG_FS
rwtm_debug_open(struct inode * inode,struct file * file)296 static int rwtm_debug_open(struct inode *inode, struct file *file)
297 {
298 file->private_data = inode->i_private;
299
300 return nonseekable_open(inode, file);
301 }
302
do_sign_read(struct file * file,char __user * buf,size_t len,loff_t * ppos)303 static ssize_t do_sign_read(struct file *file, char __user *buf, size_t len,
304 loff_t *ppos)
305 {
306 struct mox_rwtm *rwtm = file->private_data;
307 ssize_t ret;
308
309 /* only allow one read, of 136 bytes, from position 0 */
310 if (*ppos != 0)
311 return 0;
312
313 if (len < 136)
314 return -EINVAL;
315
316 if (!rwtm->last_sig_done)
317 return -ENODATA;
318
319 /* 2 arrays of 17 32-bit words are 136 bytes */
320 ret = simple_read_from_buffer(buf, len, ppos, rwtm->last_sig, 136);
321 rwtm->last_sig_done = 0;
322
323 return ret;
324 }
325
do_sign_write(struct file * file,const char __user * buf,size_t len,loff_t * ppos)326 static ssize_t do_sign_write(struct file *file, const char __user *buf,
327 size_t len, loff_t *ppos)
328 {
329 struct mox_rwtm *rwtm = file->private_data;
330 struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
331 struct armada_37xx_rwtm_tx_msg msg;
332 loff_t dummy = 0;
333 ssize_t ret;
334
335 /* the input is a SHA-512 hash, so exactly 64 bytes have to be read */
336 if (len != 64)
337 return -EINVAL;
338
339 /* if last result is not zero user has not read that information yet */
340 if (rwtm->last_sig_done)
341 return -EBUSY;
342
343 if (!mutex_trylock(&rwtm->busy))
344 return -EBUSY;
345
346 /*
347 * Here we have to send:
348 * 1. Address of the input to sign.
349 * The input is an array of 17 32-bit words, the first (most
350 * significat) is 0, the rest 16 words are copied from the SHA-512
351 * hash given by the user and converted from BE to LE.
352 * 2. Address of the buffer where ECDSA signature value R shall be
353 * stored by the rWTM firmware.
354 * 3. Address of the buffer where ECDSA signature value S shall be
355 * stored by the rWTM firmware.
356 */
357 memset(rwtm->buf, 0, 4);
358 ret = simple_write_to_buffer(rwtm->buf + 4, 64, &dummy, buf, len);
359 if (ret < 0)
360 goto unlock_mutex;
361 be32_to_cpu_array(rwtm->buf, rwtm->buf, 17);
362
363 msg.command = MBOX_CMD_SIGN;
364 msg.args[0] = 1;
365 msg.args[1] = rwtm->buf_phys;
366 msg.args[2] = rwtm->buf_phys + 68;
367 msg.args[3] = rwtm->buf_phys + 2 * 68;
368 ret = mbox_send_message(rwtm->mbox, &msg);
369 if (ret < 0)
370 goto unlock_mutex;
371
372 ret = wait_for_completion_interruptible(&rwtm->cmd_done);
373 if (ret < 0)
374 goto unlock_mutex;
375
376 ret = MBOX_STS_VALUE(reply->retval);
377 if (MBOX_STS_ERROR(reply->retval) != MBOX_STS_SUCCESS)
378 goto unlock_mutex;
379
380 /*
381 * Here we read the R and S values of the ECDSA signature
382 * computed by the rWTM firmware and convert their words from
383 * LE to BE.
384 */
385 memcpy(rwtm->last_sig, rwtm->buf + 68, 136);
386 cpu_to_be32_array(rwtm->last_sig, rwtm->last_sig, 34);
387 rwtm->last_sig_done = 1;
388
389 mutex_unlock(&rwtm->busy);
390 return len;
391 unlock_mutex:
392 mutex_unlock(&rwtm->busy);
393 return ret;
394 }
395
396 static const struct file_operations do_sign_fops = {
397 .owner = THIS_MODULE,
398 .open = rwtm_debug_open,
399 .read = do_sign_read,
400 .write = do_sign_write,
401 .llseek = no_llseek,
402 };
403
rwtm_register_debugfs(struct mox_rwtm * rwtm)404 static int rwtm_register_debugfs(struct mox_rwtm *rwtm)
405 {
406 struct dentry *root, *entry;
407
408 root = debugfs_create_dir("turris-mox-rwtm", NULL);
409
410 if (IS_ERR(root))
411 return PTR_ERR(root);
412
413 entry = debugfs_create_file_unsafe("do_sign", 0600, root, rwtm,
414 &do_sign_fops);
415 if (IS_ERR(entry))
416 goto err_remove;
417
418 rwtm->debugfs_root = root;
419
420 return 0;
421 err_remove:
422 debugfs_remove_recursive(root);
423 return PTR_ERR(entry);
424 }
425
rwtm_unregister_debugfs(struct mox_rwtm * rwtm)426 static void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
427 {
428 debugfs_remove_recursive(rwtm->debugfs_root);
429 }
430 #else
rwtm_register_debugfs(struct mox_rwtm * rwtm)431 static inline int rwtm_register_debugfs(struct mox_rwtm *rwtm)
432 {
433 return 0;
434 }
435
rwtm_unregister_debugfs(struct mox_rwtm * rwtm)436 static inline void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
437 {
438 }
439 #endif
440
turris_mox_rwtm_probe(struct platform_device * pdev)441 static int turris_mox_rwtm_probe(struct platform_device *pdev)
442 {
443 struct mox_rwtm *rwtm;
444 struct device *dev = &pdev->dev;
445 int ret;
446
447 rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
448 if (!rwtm)
449 return -ENOMEM;
450
451 rwtm->dev = dev;
452 rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
453 GFP_KERNEL);
454 if (!rwtm->buf)
455 return -ENOMEM;
456
457 ret = mox_kobj_create(rwtm);
458 if (ret < 0) {
459 dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
460 return ret;
461 }
462
463 ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
464 if (ret < 0) {
465 dev_err(dev, "Cannot create sysfs files!\n");
466 goto put_kobj;
467 }
468
469 platform_set_drvdata(pdev, rwtm);
470
471 mutex_init(&rwtm->busy);
472
473 rwtm->mbox_client.dev = dev;
474 rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;
475
476 rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
477 if (IS_ERR(rwtm->mbox)) {
478 ret = PTR_ERR(rwtm->mbox);
479 if (ret != -EPROBE_DEFER)
480 dev_err(dev, "Cannot request mailbox channel: %i\n",
481 ret);
482 goto remove_files;
483 }
484
485 init_completion(&rwtm->cmd_done);
486
487 ret = mox_get_board_info(rwtm);
488 if (ret < 0)
489 dev_warn(dev, "Cannot read board information: %i\n", ret);
490
491 rwtm->hwrng.name = DRIVER_NAME "_hwrng";
492 rwtm->hwrng.read = mox_hwrng_read;
493 rwtm->hwrng.priv = (unsigned long) rwtm;
494 rwtm->hwrng.quality = 1024;
495
496 ret = devm_hwrng_register(dev, &rwtm->hwrng);
497 if (ret < 0) {
498 dev_err(dev, "Cannot register HWRNG: %i\n", ret);
499 goto free_channel;
500 }
501
502 ret = rwtm_register_debugfs(rwtm);
503 if (ret < 0) {
504 dev_err(dev, "Failed creating debugfs entries: %i\n", ret);
505 goto free_channel;
506 }
507
508 return 0;
509
510 free_channel:
511 mbox_free_channel(rwtm->mbox);
512 remove_files:
513 sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
514 put_kobj:
515 kobject_put(rwtm_to_kobj(rwtm));
516 return ret;
517 }
518
turris_mox_rwtm_remove(struct platform_device * pdev)519 static int turris_mox_rwtm_remove(struct platform_device *pdev)
520 {
521 struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
522
523 rwtm_unregister_debugfs(rwtm);
524 sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
525 kobject_put(rwtm_to_kobj(rwtm));
526 mbox_free_channel(rwtm->mbox);
527
528 return 0;
529 }
530
531 static const struct of_device_id turris_mox_rwtm_match[] = {
532 { .compatible = "cznic,turris-mox-rwtm", },
533 { },
534 };
535
536 MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);
537
538 static struct platform_driver turris_mox_rwtm_driver = {
539 .probe = turris_mox_rwtm_probe,
540 .remove = turris_mox_rwtm_remove,
541 .driver = {
542 .name = DRIVER_NAME,
543 .of_match_table = turris_mox_rwtm_match,
544 },
545 };
546 module_platform_driver(turris_mox_rwtm_driver);
547
548 MODULE_LICENSE("GPL v2");
549 MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
550 MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
551