1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Common functions for kernel modules using Dell SMBIOS
4 *
5 * Copyright (c) Red Hat <mjg@redhat.com>
6 * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
7 * Copyright (c) 2014 Pali Rohár <pali@kernel.org>
8 *
9 * Based on documentation in the libsmbios package:
10 * Copyright (C) 2005-2014 Dell Inc.
11 */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/container_of.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/capability.h>
18 #include <linux/dmi.h>
19 #include <linux/err.h>
20 #include <linux/mutex.h>
21 #include <linux/platform_device.h>
22 #include <linux/slab.h>
23 #include "dell-smbios.h"
24
25 static u32 da_supported_commands;
26 static int da_num_tokens;
27 static struct platform_device *platform_device;
28 static struct calling_interface_token *da_tokens;
29 static struct token_sysfs_data *token_entries;
30 static struct attribute **token_attrs;
31 static DEFINE_MUTEX(smbios_mutex);
32
33 struct token_sysfs_data {
34 struct device_attribute location_attr;
35 struct device_attribute value_attr;
36 struct calling_interface_token *token;
37 };
38
39 struct smbios_device {
40 struct list_head list;
41 struct device *device;
42 int (*call_fn)(struct calling_interface_buffer *arg);
43 };
44
45 struct smbios_call {
46 u32 need_capability;
47 int cmd_class;
48 int cmd_select;
49 };
50
51 /* calls that are whitelisted for given capabilities */
52 static struct smbios_call call_whitelist[] = {
53 /* generally tokens are allowed, but may be further filtered or
54 * restricted by token blacklist or whitelist
55 */
56 {CAP_SYS_ADMIN, CLASS_TOKEN_READ, SELECT_TOKEN_STD},
57 {CAP_SYS_ADMIN, CLASS_TOKEN_READ, SELECT_TOKEN_AC},
58 {CAP_SYS_ADMIN, CLASS_TOKEN_READ, SELECT_TOKEN_BAT},
59 {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE, SELECT_TOKEN_STD},
60 {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE, SELECT_TOKEN_AC},
61 {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE, SELECT_TOKEN_BAT},
62 /* used by userspace: fwupdate */
63 {CAP_SYS_ADMIN, CLASS_ADMIN_PROP, SELECT_ADMIN_PROP},
64 /* used by userspace: fwupd */
65 {CAP_SYS_ADMIN, CLASS_INFO, SELECT_DOCK},
66 {CAP_SYS_ADMIN, CLASS_FLASH_INTERFACE, SELECT_FLASH_INTERFACE},
67 };
68
69 /* calls that are explicitly blacklisted */
70 static struct smbios_call call_blacklist[] = {
71 {0x0000, 1, 7}, /* manufacturing use */
72 {0x0000, 6, 5}, /* manufacturing use */
73 {0x0000, 11, 3}, /* write once */
74 {0x0000, 11, 7}, /* write once */
75 {0x0000, 11, 11}, /* write once */
76 {0x0000, 19, -1}, /* diagnostics */
77 /* handled by kernel: dell-laptop */
78 {0x0000, CLASS_INFO, SELECT_RFKILL},
79 {0x0000, CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT},
80 };
81
82 struct token_range {
83 u32 need_capability;
84 u16 min;
85 u16 max;
86 };
87
88 /* tokens that are whitelisted for given capabilities */
89 static struct token_range token_whitelist[] = {
90 /* used by userspace: fwupdate */
91 {CAP_SYS_ADMIN, CAPSULE_EN_TOKEN, CAPSULE_DIS_TOKEN},
92 /* can indicate to userspace that WMI is needed */
93 {0x0000, WSMT_EN_TOKEN, WSMT_DIS_TOKEN}
94 };
95
96 /* tokens that are explicitly blacklisted */
97 static struct token_range token_blacklist[] = {
98 {0x0000, 0x0058, 0x0059}, /* ME use */
99 {0x0000, 0x00CD, 0x00D0}, /* raid shadow copy */
100 {0x0000, 0x013A, 0x01FF}, /* sata shadow copy */
101 {0x0000, 0x0175, 0x0176}, /* write once */
102 {0x0000, 0x0195, 0x0197}, /* diagnostics */
103 {0x0000, 0x01DC, 0x01DD}, /* manufacturing use */
104 {0x0000, 0x027D, 0x0284}, /* diagnostics */
105 {0x0000, 0x02E3, 0x02E3}, /* manufacturing use */
106 {0x0000, 0x02FF, 0x02FF}, /* manufacturing use */
107 {0x0000, 0x0300, 0x0302}, /* manufacturing use */
108 {0x0000, 0x0325, 0x0326}, /* manufacturing use */
109 {0x0000, 0x0332, 0x0335}, /* fan control */
110 {0x0000, 0x0350, 0x0350}, /* manufacturing use */
111 {0x0000, 0x0363, 0x0363}, /* manufacturing use */
112 {0x0000, 0x0368, 0x0368}, /* manufacturing use */
113 {0x0000, 0x03F6, 0x03F7}, /* manufacturing use */
114 {0x0000, 0x049E, 0x049F}, /* manufacturing use */
115 {0x0000, 0x04A0, 0x04A3}, /* disagnostics */
116 {0x0000, 0x04E6, 0x04E7}, /* manufacturing use */
117 {0x0000, 0x4000, 0x7FFF}, /* internal BIOS use */
118 {0x0000, 0x9000, 0x9001}, /* internal BIOS use */
119 {0x0000, 0xA000, 0xBFFF}, /* write only */
120 {0x0000, 0xEFF0, 0xEFFF}, /* internal BIOS use */
121 /* handled by kernel: dell-laptop */
122 {0x0000, BRIGHTNESS_TOKEN, BRIGHTNESS_TOKEN},
123 {0x0000, KBD_LED_OFF_TOKEN, KBD_LED_AUTO_TOKEN},
124 {0x0000, KBD_LED_AC_TOKEN, KBD_LED_AC_TOKEN},
125 {0x0000, KBD_LED_AUTO_25_TOKEN, KBD_LED_AUTO_75_TOKEN},
126 {0x0000, KBD_LED_AUTO_100_TOKEN, KBD_LED_AUTO_100_TOKEN},
127 {0x0000, GLOBAL_MIC_MUTE_ENABLE, GLOBAL_MIC_MUTE_DISABLE},
128 };
129
130 static LIST_HEAD(smbios_device_list);
131
dell_smbios_error(int value)132 int dell_smbios_error(int value)
133 {
134 switch (value) {
135 case 0: /* Completed successfully */
136 return 0;
137 case -1: /* Completed with error */
138 return -EIO;
139 case -2: /* Function not supported */
140 return -ENXIO;
141 default: /* Unknown error */
142 return -EINVAL;
143 }
144 }
145 EXPORT_SYMBOL_GPL(dell_smbios_error);
146
dell_smbios_register_device(struct device * d,void * call_fn)147 int dell_smbios_register_device(struct device *d, void *call_fn)
148 {
149 struct smbios_device *priv;
150
151 priv = devm_kzalloc(d, sizeof(struct smbios_device), GFP_KERNEL);
152 if (!priv)
153 return -ENOMEM;
154 get_device(d);
155 priv->device = d;
156 priv->call_fn = call_fn;
157 mutex_lock(&smbios_mutex);
158 list_add_tail(&priv->list, &smbios_device_list);
159 mutex_unlock(&smbios_mutex);
160 dev_dbg(d, "Added device: %s\n", d->driver->name);
161 return 0;
162 }
163 EXPORT_SYMBOL_GPL(dell_smbios_register_device);
164
dell_smbios_unregister_device(struct device * d)165 void dell_smbios_unregister_device(struct device *d)
166 {
167 struct smbios_device *priv;
168
169 mutex_lock(&smbios_mutex);
170 list_for_each_entry(priv, &smbios_device_list, list) {
171 if (priv->device == d) {
172 list_del(&priv->list);
173 put_device(d);
174 break;
175 }
176 }
177 mutex_unlock(&smbios_mutex);
178 dev_dbg(d, "Remove device: %s\n", d->driver->name);
179 }
180 EXPORT_SYMBOL_GPL(dell_smbios_unregister_device);
181
dell_smbios_call_filter(struct device * d,struct calling_interface_buffer * buffer)182 int dell_smbios_call_filter(struct device *d,
183 struct calling_interface_buffer *buffer)
184 {
185 u16 t = 0;
186 int i;
187
188 /* can't make calls over 30 */
189 if (buffer->cmd_class > 30) {
190 dev_dbg(d, "class too big: %u\n", buffer->cmd_class);
191 return -EINVAL;
192 }
193
194 /* supported calls on the particular system */
195 if (!(da_supported_commands & (1 << buffer->cmd_class))) {
196 dev_dbg(d, "invalid command, supported commands: 0x%8x\n",
197 da_supported_commands);
198 return -EINVAL;
199 }
200
201 /* match against call blacklist */
202 for (i = 0; i < ARRAY_SIZE(call_blacklist); i++) {
203 if (buffer->cmd_class != call_blacklist[i].cmd_class)
204 continue;
205 if (buffer->cmd_select != call_blacklist[i].cmd_select &&
206 call_blacklist[i].cmd_select != -1)
207 continue;
208 dev_dbg(d, "blacklisted command: %u/%u\n",
209 buffer->cmd_class, buffer->cmd_select);
210 return -EINVAL;
211 }
212
213 /* if a token call, find token ID */
214
215 if ((buffer->cmd_class == CLASS_TOKEN_READ ||
216 buffer->cmd_class == CLASS_TOKEN_WRITE) &&
217 buffer->cmd_select < 3) {
218 /* tokens enabled ? */
219 if (!da_tokens) {
220 dev_dbg(d, "no token support on this system\n");
221 return -EINVAL;
222 }
223
224 /* find the matching token ID */
225 for (i = 0; i < da_num_tokens; i++) {
226 if (da_tokens[i].location != buffer->input[0])
227 continue;
228 t = da_tokens[i].tokenID;
229 break;
230 }
231
232 /* token call; but token didn't exist */
233 if (!t) {
234 dev_dbg(d, "token at location %04x doesn't exist\n",
235 buffer->input[0]);
236 return -EINVAL;
237 }
238
239 /* match against token blacklist */
240 for (i = 0; i < ARRAY_SIZE(token_blacklist); i++) {
241 if (!token_blacklist[i].min || !token_blacklist[i].max)
242 continue;
243 if (t >= token_blacklist[i].min &&
244 t <= token_blacklist[i].max)
245 return -EINVAL;
246 }
247
248 /* match against token whitelist */
249 for (i = 0; i < ARRAY_SIZE(token_whitelist); i++) {
250 if (!token_whitelist[i].min || !token_whitelist[i].max)
251 continue;
252 if (t < token_whitelist[i].min ||
253 t > token_whitelist[i].max)
254 continue;
255 if (!token_whitelist[i].need_capability ||
256 capable(token_whitelist[i].need_capability)) {
257 dev_dbg(d, "whitelisted token: %x\n", t);
258 return 0;
259 }
260
261 }
262 }
263 /* match against call whitelist */
264 for (i = 0; i < ARRAY_SIZE(call_whitelist); i++) {
265 if (buffer->cmd_class != call_whitelist[i].cmd_class)
266 continue;
267 if (buffer->cmd_select != call_whitelist[i].cmd_select)
268 continue;
269 if (!call_whitelist[i].need_capability ||
270 capable(call_whitelist[i].need_capability)) {
271 dev_dbg(d, "whitelisted capable command: %u/%u\n",
272 buffer->cmd_class, buffer->cmd_select);
273 return 0;
274 }
275 dev_dbg(d, "missing capability %d for %u/%u\n",
276 call_whitelist[i].need_capability,
277 buffer->cmd_class, buffer->cmd_select);
278
279 }
280
281 /* not in a whitelist, only allow processes with capabilities */
282 if (capable(CAP_SYS_RAWIO)) {
283 dev_dbg(d, "Allowing %u/%u due to CAP_SYS_RAWIO\n",
284 buffer->cmd_class, buffer->cmd_select);
285 return 0;
286 }
287
288 return -EACCES;
289 }
290 EXPORT_SYMBOL_GPL(dell_smbios_call_filter);
291
dell_smbios_call(struct calling_interface_buffer * buffer)292 int dell_smbios_call(struct calling_interface_buffer *buffer)
293 {
294 int (*call_fn)(struct calling_interface_buffer *) = NULL;
295 struct device *selected_dev = NULL;
296 struct smbios_device *priv;
297 int ret;
298
299 mutex_lock(&smbios_mutex);
300 list_for_each_entry(priv, &smbios_device_list, list) {
301 if (!selected_dev || priv->device->id >= selected_dev->id) {
302 dev_dbg(priv->device, "Trying device ID: %d\n",
303 priv->device->id);
304 call_fn = priv->call_fn;
305 selected_dev = priv->device;
306 }
307 }
308
309 if (!selected_dev) {
310 ret = -ENODEV;
311 pr_err("No dell-smbios drivers are loaded\n");
312 goto out_smbios_call;
313 }
314
315 ret = call_fn(buffer);
316
317 out_smbios_call:
318 mutex_unlock(&smbios_mutex);
319 return ret;
320 }
321 EXPORT_SYMBOL_GPL(dell_smbios_call);
322
dell_smbios_find_token(int tokenid)323 struct calling_interface_token *dell_smbios_find_token(int tokenid)
324 {
325 int i;
326
327 if (!da_tokens)
328 return NULL;
329
330 for (i = 0; i < da_num_tokens; i++) {
331 if (da_tokens[i].tokenID == tokenid)
332 return &da_tokens[i];
333 }
334
335 return NULL;
336 }
337 EXPORT_SYMBOL_GPL(dell_smbios_find_token);
338
339 static BLOCKING_NOTIFIER_HEAD(dell_laptop_chain_head);
340
dell_laptop_register_notifier(struct notifier_block * nb)341 int dell_laptop_register_notifier(struct notifier_block *nb)
342 {
343 return blocking_notifier_chain_register(&dell_laptop_chain_head, nb);
344 }
345 EXPORT_SYMBOL_GPL(dell_laptop_register_notifier);
346
dell_laptop_unregister_notifier(struct notifier_block * nb)347 int dell_laptop_unregister_notifier(struct notifier_block *nb)
348 {
349 return blocking_notifier_chain_unregister(&dell_laptop_chain_head, nb);
350 }
351 EXPORT_SYMBOL_GPL(dell_laptop_unregister_notifier);
352
dell_laptop_call_notifier(unsigned long action,void * data)353 void dell_laptop_call_notifier(unsigned long action, void *data)
354 {
355 blocking_notifier_call_chain(&dell_laptop_chain_head, action, data);
356 }
357 EXPORT_SYMBOL_GPL(dell_laptop_call_notifier);
358
parse_da_table(const struct dmi_header * dm)359 static void __init parse_da_table(const struct dmi_header *dm)
360 {
361 /* Final token is a terminator, so we don't want to copy it */
362 int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
363 struct calling_interface_token *new_da_tokens;
364 struct calling_interface_structure *table =
365 container_of(dm, struct calling_interface_structure, header);
366
367 /*
368 * 4 bytes of table header, plus 7 bytes of Dell header
369 * plus at least 6 bytes of entry
370 */
371
372 if (dm->length < 17)
373 return;
374
375 da_supported_commands = table->supportedCmds;
376
377 new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
378 sizeof(struct calling_interface_token),
379 GFP_KERNEL);
380
381 if (!new_da_tokens)
382 return;
383 da_tokens = new_da_tokens;
384
385 memcpy(da_tokens+da_num_tokens, table->tokens,
386 sizeof(struct calling_interface_token) * tokens);
387
388 da_num_tokens += tokens;
389 }
390
zero_duplicates(struct device * dev)391 static void zero_duplicates(struct device *dev)
392 {
393 int i, j;
394
395 for (i = 0; i < da_num_tokens; i++) {
396 if (da_tokens[i].tokenID == 0)
397 continue;
398 for (j = i+1; j < da_num_tokens; j++) {
399 if (da_tokens[j].tokenID == 0)
400 continue;
401 if (da_tokens[i].tokenID == da_tokens[j].tokenID) {
402 dev_dbg(dev, "Zeroing dup token ID %x(%x/%x)\n",
403 da_tokens[j].tokenID,
404 da_tokens[j].location,
405 da_tokens[j].value);
406 da_tokens[j].tokenID = 0;
407 }
408 }
409 }
410 }
411
find_tokens(const struct dmi_header * dm,void * dummy)412 static void __init find_tokens(const struct dmi_header *dm, void *dummy)
413 {
414 switch (dm->type) {
415 case 0xd4: /* Indexed IO */
416 case 0xd5: /* Protected Area Type 1 */
417 case 0xd6: /* Protected Area Type 2 */
418 break;
419 case 0xda: /* Calling interface */
420 parse_da_table(dm);
421 break;
422 }
423 }
424
location_show(struct device * dev,struct device_attribute * attr,char * buf)425 static ssize_t location_show(struct device *dev,
426 struct device_attribute *attr, char *buf)
427 {
428 struct token_sysfs_data *data = container_of(attr, struct token_sysfs_data, location_attr);
429
430 if (!capable(CAP_SYS_ADMIN))
431 return -EPERM;
432
433 return sysfs_emit(buf, "%08x", data->token->location);
434 }
435
value_show(struct device * dev,struct device_attribute * attr,char * buf)436 static ssize_t value_show(struct device *dev,
437 struct device_attribute *attr, char *buf)
438 {
439 struct token_sysfs_data *data = container_of(attr, struct token_sysfs_data, value_attr);
440
441 if (!capable(CAP_SYS_ADMIN))
442 return -EPERM;
443
444 return sysfs_emit(buf, "%08x", data->token->value);
445 }
446
447 static struct attribute_group smbios_attribute_group = {
448 .name = "tokens"
449 };
450
451 static struct platform_driver platform_driver = {
452 .driver = {
453 .name = "dell-smbios",
454 },
455 };
456
build_tokens_sysfs(struct platform_device * dev)457 static int build_tokens_sysfs(struct platform_device *dev)
458 {
459 char *location_name;
460 char *value_name;
461 int ret;
462 int i, j;
463
464 token_entries = kcalloc(da_num_tokens, sizeof(*token_entries), GFP_KERNEL);
465 if (!token_entries)
466 return -ENOMEM;
467
468 /* need to store both location and value + terminator*/
469 token_attrs = kcalloc((2 * da_num_tokens) + 1, sizeof(*token_attrs), GFP_KERNEL);
470 if (!token_attrs)
471 goto out_allocate_attrs;
472
473 for (i = 0, j = 0; i < da_num_tokens; i++) {
474 /* skip empty */
475 if (da_tokens[i].tokenID == 0)
476 continue;
477
478 token_entries[i].token = &da_tokens[i];
479
480 /* add location */
481 location_name = kasprintf(GFP_KERNEL, "%04x_location",
482 da_tokens[i].tokenID);
483 if (location_name == NULL)
484 goto out_unwind_strings;
485
486 sysfs_attr_init(&token_entries[i].location_attr.attr);
487 token_entries[i].location_attr.attr.name = location_name;
488 token_entries[i].location_attr.attr.mode = 0444;
489 token_entries[i].location_attr.show = location_show;
490 token_attrs[j++] = &token_entries[i].location_attr.attr;
491
492 /* add value */
493 value_name = kasprintf(GFP_KERNEL, "%04x_value",
494 da_tokens[i].tokenID);
495 if (value_name == NULL)
496 goto loop_fail_create_value;
497
498 sysfs_attr_init(&token_entries[i].value_attr.attr);
499 token_entries[i].value_attr.attr.name = value_name;
500 token_entries[i].value_attr.attr.mode = 0444;
501 token_entries[i].value_attr.show = value_show;
502 token_attrs[j++] = &token_entries[i].value_attr.attr;
503 continue;
504
505 loop_fail_create_value:
506 kfree(location_name);
507 goto out_unwind_strings;
508 }
509 smbios_attribute_group.attrs = token_attrs;
510
511 ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group);
512 if (ret)
513 goto out_unwind_strings;
514 return 0;
515
516 out_unwind_strings:
517 while (i--) {
518 kfree(token_entries[i].location_attr.attr.name);
519 kfree(token_entries[i].value_attr.attr.name);
520 }
521 kfree(token_attrs);
522 out_allocate_attrs:
523 kfree(token_entries);
524
525 return -ENOMEM;
526 }
527
free_group(struct platform_device * pdev)528 static void free_group(struct platform_device *pdev)
529 {
530 int i;
531
532 sysfs_remove_group(&pdev->dev.kobj,
533 &smbios_attribute_group);
534 for (i = 0; i < da_num_tokens; i++) {
535 kfree(token_entries[i].location_attr.attr.name);
536 kfree(token_entries[i].value_attr.attr.name);
537 }
538 kfree(token_attrs);
539 kfree(token_entries);
540 }
541
dell_smbios_init(void)542 static int __init dell_smbios_init(void)
543 {
544 int ret, wmi, smm;
545
546 if (!dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System", NULL) &&
547 !dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "www.dell.com", NULL)) {
548 pr_err("Unable to run on non-Dell system\n");
549 return -ENODEV;
550 }
551
552 dmi_walk(find_tokens, NULL);
553
554 ret = platform_driver_register(&platform_driver);
555 if (ret)
556 goto fail_platform_driver;
557
558 platform_device = platform_device_alloc("dell-smbios", 0);
559 if (!platform_device) {
560 ret = -ENOMEM;
561 goto fail_platform_device_alloc;
562 }
563 ret = platform_device_add(platform_device);
564 if (ret)
565 goto fail_platform_device_add;
566
567 /* register backends */
568 wmi = init_dell_smbios_wmi();
569 if (wmi)
570 pr_debug("Failed to initialize WMI backend: %d\n", wmi);
571 smm = init_dell_smbios_smm();
572 if (smm)
573 pr_debug("Failed to initialize SMM backend: %d\n", smm);
574 if (wmi && smm) {
575 pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
576 wmi, smm);
577 ret = -ENODEV;
578 goto fail_create_group;
579 }
580
581 if (da_tokens) {
582 /* duplicate tokens will cause problems building sysfs files */
583 zero_duplicates(&platform_device->dev);
584
585 ret = build_tokens_sysfs(platform_device);
586 if (ret)
587 goto fail_sysfs;
588 }
589
590 return 0;
591
592 fail_sysfs:
593 free_group(platform_device);
594
595 fail_create_group:
596 platform_device_del(platform_device);
597
598 fail_platform_device_add:
599 platform_device_put(platform_device);
600
601 fail_platform_device_alloc:
602 platform_driver_unregister(&platform_driver);
603
604 fail_platform_driver:
605 kfree(da_tokens);
606 return ret;
607 }
608
dell_smbios_exit(void)609 static void __exit dell_smbios_exit(void)
610 {
611 exit_dell_smbios_wmi();
612 exit_dell_smbios_smm();
613 mutex_lock(&smbios_mutex);
614 if (platform_device) {
615 if (da_tokens)
616 free_group(platform_device);
617 platform_device_unregister(platform_device);
618 platform_driver_unregister(&platform_driver);
619 }
620 kfree(da_tokens);
621 mutex_unlock(&smbios_mutex);
622 }
623
624 module_init(dell_smbios_init);
625 module_exit(dell_smbios_exit);
626
627 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
628 MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
629 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
630 MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");
631 MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
632 MODULE_LICENSE("GPL");
633