1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Turris Mox rWTM firmware driver
4 *
5 * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
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 return -EIO;
152 else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
153 return -(int)MBOX_STS_VALUE(retval);
154 else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
155 return -ENOSYS;
156 else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
157 return -EIO;
158 else
159 return MBOX_STS_VALUE(retval);
160 }
161
162 static const struct attribute *mox_rwtm_attrs[] = {
163 &mox_attr_serial_number.attr,
164 &mox_attr_board_version.attr,
165 &mox_attr_ram_size.attr,
166 &mox_attr_mac_address1.attr,
167 &mox_attr_mac_address2.attr,
168 &mox_attr_pubkey.attr,
169 NULL
170 };
171
mox_rwtm_rx_callback(struct mbox_client * cl,void * data)172 static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
173 {
174 struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
175 struct armada_37xx_rwtm_rx_msg *msg = data;
176
177 rwtm->reply = *msg;
178 complete(&rwtm->cmd_done);
179 }
180
reply_to_mac_addr(u8 * mac,u32 t1,u32 t2)181 static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
182 {
183 mac[0] = t1 >> 8;
184 mac[1] = t1;
185 mac[2] = t2 >> 24;
186 mac[3] = t2 >> 16;
187 mac[4] = t2 >> 8;
188 mac[5] = t2;
189 }
190
mox_get_board_info(struct mox_rwtm * rwtm)191 static int mox_get_board_info(struct mox_rwtm *rwtm)
192 {
193 struct armada_37xx_rwtm_tx_msg msg;
194 struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
195 int ret;
196
197 msg.command = MBOX_CMD_BOARD_INFO;
198 ret = mbox_send_message(rwtm->mbox, &msg);
199 if (ret < 0)
200 return ret;
201
202 ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
203 if (ret < 0)
204 return ret;
205
206 ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
207 if (ret == -ENODATA) {
208 dev_warn(rwtm->dev,
209 "Board does not have manufacturing information burned!\n");
210 } else if (ret == -ENOSYS) {
211 dev_notice(rwtm->dev,
212 "Firmware does not support the BOARD_INFO command\n");
213 } else if (ret < 0) {
214 return ret;
215 } else {
216 rwtm->serial_number = reply->status[1];
217 rwtm->serial_number <<= 32;
218 rwtm->serial_number |= reply->status[0];
219 rwtm->board_version = reply->status[2];
220 rwtm->ram_size = reply->status[3];
221 reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
222 reply->status[5]);
223 reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
224 reply->status[7]);
225 rwtm->has_board_info = 1;
226
227 pr_info("Turris Mox serial number %016llX\n",
228 rwtm->serial_number);
229 pr_info(" board version %i\n", rwtm->board_version);
230 pr_info(" burned RAM size %i MiB\n", rwtm->ram_size);
231 }
232
233 msg.command = MBOX_CMD_ECDSA_PUB_KEY;
234 ret = mbox_send_message(rwtm->mbox, &msg);
235 if (ret < 0)
236 return ret;
237
238 ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
239 if (ret < 0)
240 return ret;
241
242 ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
243 if (ret == -ENODATA) {
244 dev_warn(rwtm->dev, "Board has no public key burned!\n");
245 } else if (ret == -ENOSYS) {
246 dev_notice(rwtm->dev,
247 "Firmware does not support the ECDSA_PUB_KEY command\n");
248 } else if (ret < 0) {
249 return ret;
250 } else {
251 u32 *s = reply->status;
252
253 rwtm->has_pubkey = 1;
254 sprintf(rwtm->pubkey,
255 "%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
256 ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
257 s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
258 }
259
260 return 0;
261 }
262
check_get_random_support(struct mox_rwtm * rwtm)263 static int check_get_random_support(struct mox_rwtm *rwtm)
264 {
265 struct armada_37xx_rwtm_tx_msg msg;
266 int ret;
267
268 msg.command = MBOX_CMD_GET_RANDOM;
269 msg.args[0] = 1;
270 msg.args[1] = rwtm->buf_phys;
271 msg.args[2] = 4;
272
273 ret = mbox_send_message(rwtm->mbox, &msg);
274 if (ret < 0)
275 return ret;
276
277 ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
278 if (ret < 0)
279 return ret;
280
281 return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
282 }
283
mox_hwrng_read(struct hwrng * rng,void * data,size_t max,bool wait)284 static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
285 {
286 struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
287 struct armada_37xx_rwtm_tx_msg msg;
288 int ret;
289
290 if (max > 4096)
291 max = 4096;
292
293 msg.command = MBOX_CMD_GET_RANDOM;
294 msg.args[0] = 1;
295 msg.args[1] = rwtm->buf_phys;
296 msg.args[2] = (max + 3) & ~3;
297
298 if (!wait) {
299 if (!mutex_trylock(&rwtm->busy))
300 return -EBUSY;
301 } else {
302 mutex_lock(&rwtm->busy);
303 }
304
305 ret = mbox_send_message(rwtm->mbox, &msg);
306 if (ret < 0)
307 goto unlock_mutex;
308
309 ret = wait_for_completion_interruptible(&rwtm->cmd_done);
310 if (ret < 0)
311 goto unlock_mutex;
312
313 ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
314 if (ret < 0)
315 goto unlock_mutex;
316
317 memcpy(data, rwtm->buf, max);
318 ret = max;
319
320 unlock_mutex:
321 mutex_unlock(&rwtm->busy);
322 return ret;
323 }
324
325 #ifdef CONFIG_DEBUG_FS
rwtm_debug_open(struct inode * inode,struct file * file)326 static int rwtm_debug_open(struct inode *inode, struct file *file)
327 {
328 file->private_data = inode->i_private;
329
330 return nonseekable_open(inode, file);
331 }
332
do_sign_read(struct file * file,char __user * buf,size_t len,loff_t * ppos)333 static ssize_t do_sign_read(struct file *file, char __user *buf, size_t len,
334 loff_t *ppos)
335 {
336 struct mox_rwtm *rwtm = file->private_data;
337 ssize_t ret;
338
339 /* only allow one read, of 136 bytes, from position 0 */
340 if (*ppos != 0)
341 return 0;
342
343 if (len < 136)
344 return -EINVAL;
345
346 if (!rwtm->last_sig_done)
347 return -ENODATA;
348
349 /* 2 arrays of 17 32-bit words are 136 bytes */
350 ret = simple_read_from_buffer(buf, len, ppos, rwtm->last_sig, 136);
351 rwtm->last_sig_done = 0;
352
353 return ret;
354 }
355
do_sign_write(struct file * file,const char __user * buf,size_t len,loff_t * ppos)356 static ssize_t do_sign_write(struct file *file, const char __user *buf,
357 size_t len, loff_t *ppos)
358 {
359 struct mox_rwtm *rwtm = file->private_data;
360 struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
361 struct armada_37xx_rwtm_tx_msg msg;
362 loff_t dummy = 0;
363 ssize_t ret;
364
365 /* the input is a SHA-512 hash, so exactly 64 bytes have to be read */
366 if (len != 64)
367 return -EINVAL;
368
369 /* if last result is not zero user has not read that information yet */
370 if (rwtm->last_sig_done)
371 return -EBUSY;
372
373 if (!mutex_trylock(&rwtm->busy))
374 return -EBUSY;
375
376 /*
377 * Here we have to send:
378 * 1. Address of the input to sign.
379 * The input is an array of 17 32-bit words, the first (most
380 * significat) is 0, the rest 16 words are copied from the SHA-512
381 * hash given by the user and converted from BE to LE.
382 * 2. Address of the buffer where ECDSA signature value R shall be
383 * stored by the rWTM firmware.
384 * 3. Address of the buffer where ECDSA signature value S shall be
385 * stored by the rWTM firmware.
386 */
387 memset(rwtm->buf, 0, 4);
388 ret = simple_write_to_buffer(rwtm->buf + 4, 64, &dummy, buf, len);
389 if (ret < 0)
390 goto unlock_mutex;
391 be32_to_cpu_array(rwtm->buf, rwtm->buf, 17);
392
393 msg.command = MBOX_CMD_SIGN;
394 msg.args[0] = 1;
395 msg.args[1] = rwtm->buf_phys;
396 msg.args[2] = rwtm->buf_phys + 68;
397 msg.args[3] = rwtm->buf_phys + 2 * 68;
398 ret = mbox_send_message(rwtm->mbox, &msg);
399 if (ret < 0)
400 goto unlock_mutex;
401
402 ret = wait_for_completion_interruptible(&rwtm->cmd_done);
403 if (ret < 0)
404 goto unlock_mutex;
405
406 ret = MBOX_STS_VALUE(reply->retval);
407 if (MBOX_STS_ERROR(reply->retval) != MBOX_STS_SUCCESS)
408 goto unlock_mutex;
409
410 /*
411 * Here we read the R and S values of the ECDSA signature
412 * computed by the rWTM firmware and convert their words from
413 * LE to BE.
414 */
415 memcpy(rwtm->last_sig, rwtm->buf + 68, 136);
416 cpu_to_be32_array(rwtm->last_sig, rwtm->last_sig, 34);
417 rwtm->last_sig_done = 1;
418
419 mutex_unlock(&rwtm->busy);
420 return len;
421 unlock_mutex:
422 mutex_unlock(&rwtm->busy);
423 return ret;
424 }
425
426 static const struct file_operations do_sign_fops = {
427 .owner = THIS_MODULE,
428 .open = rwtm_debug_open,
429 .read = do_sign_read,
430 .write = do_sign_write,
431 .llseek = no_llseek,
432 };
433
rwtm_register_debugfs(struct mox_rwtm * rwtm)434 static int rwtm_register_debugfs(struct mox_rwtm *rwtm)
435 {
436 struct dentry *root, *entry;
437
438 root = debugfs_create_dir("turris-mox-rwtm", NULL);
439
440 if (IS_ERR(root))
441 return PTR_ERR(root);
442
443 entry = debugfs_create_file_unsafe("do_sign", 0600, root, rwtm,
444 &do_sign_fops);
445 if (IS_ERR(entry))
446 goto err_remove;
447
448 rwtm->debugfs_root = root;
449
450 return 0;
451 err_remove:
452 debugfs_remove_recursive(root);
453 return PTR_ERR(entry);
454 }
455
rwtm_unregister_debugfs(struct mox_rwtm * rwtm)456 static void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
457 {
458 debugfs_remove_recursive(rwtm->debugfs_root);
459 }
460 #else
rwtm_register_debugfs(struct mox_rwtm * rwtm)461 static inline int rwtm_register_debugfs(struct mox_rwtm *rwtm)
462 {
463 return 0;
464 }
465
rwtm_unregister_debugfs(struct mox_rwtm * rwtm)466 static inline void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
467 {
468 }
469 #endif
470
turris_mox_rwtm_probe(struct platform_device * pdev)471 static int turris_mox_rwtm_probe(struct platform_device *pdev)
472 {
473 struct mox_rwtm *rwtm;
474 struct device *dev = &pdev->dev;
475 int ret;
476
477 rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
478 if (!rwtm)
479 return -ENOMEM;
480
481 rwtm->dev = dev;
482 rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
483 GFP_KERNEL);
484 if (!rwtm->buf)
485 return -ENOMEM;
486
487 ret = mox_kobj_create(rwtm);
488 if (ret < 0) {
489 dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
490 return ret;
491 }
492
493 ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
494 if (ret < 0) {
495 dev_err(dev, "Cannot create sysfs files!\n");
496 goto put_kobj;
497 }
498
499 platform_set_drvdata(pdev, rwtm);
500
501 mutex_init(&rwtm->busy);
502
503 rwtm->mbox_client.dev = dev;
504 rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;
505
506 rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
507 if (IS_ERR(rwtm->mbox)) {
508 ret = PTR_ERR(rwtm->mbox);
509 if (ret != -EPROBE_DEFER)
510 dev_err(dev, "Cannot request mailbox channel: %i\n",
511 ret);
512 goto remove_files;
513 }
514
515 init_completion(&rwtm->cmd_done);
516
517 ret = mox_get_board_info(rwtm);
518 if (ret < 0)
519 dev_warn(dev, "Cannot read board information: %i\n", ret);
520
521 ret = check_get_random_support(rwtm);
522 if (ret < 0) {
523 dev_notice(dev,
524 "Firmware does not support the GET_RANDOM command\n");
525 goto free_channel;
526 }
527
528 rwtm->hwrng.name = DRIVER_NAME "_hwrng";
529 rwtm->hwrng.read = mox_hwrng_read;
530 rwtm->hwrng.priv = (unsigned long) rwtm;
531 rwtm->hwrng.quality = 1024;
532
533 ret = devm_hwrng_register(dev, &rwtm->hwrng);
534 if (ret < 0) {
535 dev_err(dev, "Cannot register HWRNG: %i\n", ret);
536 goto free_channel;
537 }
538
539 ret = rwtm_register_debugfs(rwtm);
540 if (ret < 0) {
541 dev_err(dev, "Failed creating debugfs entries: %i\n", ret);
542 goto free_channel;
543 }
544
545 dev_info(dev, "HWRNG successfully registered\n");
546
547 return 0;
548
549 free_channel:
550 mbox_free_channel(rwtm->mbox);
551 remove_files:
552 sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
553 put_kobj:
554 kobject_put(rwtm_to_kobj(rwtm));
555 return ret;
556 }
557
turris_mox_rwtm_remove(struct platform_device * pdev)558 static int turris_mox_rwtm_remove(struct platform_device *pdev)
559 {
560 struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
561
562 rwtm_unregister_debugfs(rwtm);
563 sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
564 kobject_put(rwtm_to_kobj(rwtm));
565 mbox_free_channel(rwtm->mbox);
566
567 return 0;
568 }
569
570 static const struct of_device_id turris_mox_rwtm_match[] = {
571 { .compatible = "cznic,turris-mox-rwtm", },
572 { .compatible = "marvell,armada-3700-rwtm-firmware", },
573 { },
574 };
575
576 MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);
577
578 static struct platform_driver turris_mox_rwtm_driver = {
579 .probe = turris_mox_rwtm_probe,
580 .remove = turris_mox_rwtm_remove,
581 .driver = {
582 .name = DRIVER_NAME,
583 .of_match_table = turris_mox_rwtm_match,
584 },
585 };
586 module_platform_driver(turris_mox_rwtm_driver);
587
588 MODULE_LICENSE("GPL v2");
589 MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
590 MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
591