1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/types.h>
  4#include <linux/kconfig.h>
  5#include <linux/list.h>
  6#include <linux/slab.h>
  7#include <linux/security.h>
  8#include <linux/highmem.h>
  9#include <linux/umh.h>
 10#include <linux/sysctl.h>
 11#include <linux/vmalloc.h>
 12#include <linux/module.h>
 13
 14#include "fallback.h"
 15#include "firmware.h"
 16
 17/*
 18 * firmware fallback mechanism
 19 */
 20
 21MODULE_IMPORT_NS(FIRMWARE_LOADER_PRIVATE);
 22
 23extern struct firmware_fallback_config fw_fallback_config;
 24
 25/* These getters are vetted to use int properly */
 26static inline int __firmware_loading_timeout(void)
 27{
 28	return fw_fallback_config.loading_timeout;
 29}
 30
 31/* These setters are vetted to use int properly */
 32static void __fw_fallback_set_timeout(int timeout)
 33{
 34	fw_fallback_config.loading_timeout = timeout;
 35}
 36
 37/*
 38 * use small loading timeout for caching devices' firmware because all these
 39 * firmware images have been loaded successfully at lease once, also system is
 40 * ready for completing firmware loading now. The maximum size of firmware in
 41 * current distributions is about 2M bytes, so 10 secs should be enough.
 42 */
 43void fw_fallback_set_cache_timeout(void)
 44{
 45	fw_fallback_config.old_timeout = __firmware_loading_timeout();
 46	__fw_fallback_set_timeout(10);
 47}
 48
 49/* Restores the timeout to the value last configured during normal operation */
 50void fw_fallback_set_default_timeout(void)
 51{
 52	__fw_fallback_set_timeout(fw_fallback_config.old_timeout);
 53}
 54
 55static long firmware_loading_timeout(void)
 56{
 57	return __firmware_loading_timeout() > 0 ?
 58		__firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
 59}
 60
 61static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
 62{
 63	return __fw_state_check(fw_priv, FW_STATUS_DONE);
 64}
 65
 66static inline bool fw_sysfs_loading(struct fw_priv *fw_priv)
 67{
 68	return __fw_state_check(fw_priv, FW_STATUS_LOADING);
 69}
 70
 71static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv,  long timeout)
 72{
 73	return __fw_state_wait_common(fw_priv, timeout);
 74}
 75
 76struct fw_sysfs {
 77	bool nowait;
 78	struct device dev;
 79	struct fw_priv *fw_priv;
 80	struct firmware *fw;
 81};
 82
 83static struct fw_sysfs *to_fw_sysfs(struct device *dev)
 84{
 85	return container_of(dev, struct fw_sysfs, dev);
 86}
 87
 88static void __fw_load_abort(struct fw_priv *fw_priv)
 89{
 90	/*
 91	 * There is a small window in which user can write to 'loading'
 92	 * between loading done and disappearance of 'loading'
 93	 */
 94	if (fw_sysfs_done(fw_priv))
 95		return;
 96
 97	list_del_init(&fw_priv->pending_list);
 98	fw_state_aborted(fw_priv);
 99}
100
101static void fw_load_abort(struct fw_sysfs *fw_sysfs)
102{
103	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
104
105	__fw_load_abort(fw_priv);
106}
107
108static LIST_HEAD(pending_fw_head);
109
110void kill_pending_fw_fallback_reqs(bool only_kill_custom)
111{
112	struct fw_priv *fw_priv;
113	struct fw_priv *next;
114
115	mutex_lock(&fw_lock);
116	list_for_each_entry_safe(fw_priv, next, &pending_fw_head,
117				 pending_list) {
118		if (!fw_priv->need_uevent || !only_kill_custom)
119			 __fw_load_abort(fw_priv);
120	}
121	mutex_unlock(&fw_lock);
122}
123
124static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
125			    char *buf)
126{
127	return sprintf(buf, "%d\n", __firmware_loading_timeout());
128}
129
130/**
131 * firmware_timeout_store() - set number of seconds to wait for firmware
132 * @class: device class pointer
133 * @attr: device attribute pointer
134 * @buf: buffer to scan for timeout value
135 * @count: number of bytes in @buf
136 *
137 *	Sets the number of seconds to wait for the firmware.  Once
138 *	this expires an error will be returned to the driver and no
139 *	firmware will be provided.
140 *
141 *	Note: zero means 'wait forever'.
142 **/
143static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
144			     const char *buf, size_t count)
145{
146	int tmp_loading_timeout = simple_strtol(buf, NULL, 10);
147
148	if (tmp_loading_timeout < 0)
149		tmp_loading_timeout = 0;
150
151	__fw_fallback_set_timeout(tmp_loading_timeout);
152
153	return count;
154}
155static CLASS_ATTR_RW(timeout);
156
157static struct attribute *firmware_class_attrs[] = {
158	&class_attr_timeout.attr,
159	NULL,
160};
161ATTRIBUTE_GROUPS(firmware_class);
162
163static void fw_dev_release(struct device *dev)
164{
165	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
166
167	kfree(fw_sysfs);
168}
169
170static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env *env)
171{
172	if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
173		return -ENOMEM;
174	if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
175		return -ENOMEM;
176	if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
177		return -ENOMEM;
178
179	return 0;
180}
181
182static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
183{
184	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
185	int err = 0;
186
187	mutex_lock(&fw_lock);
188	if (fw_sysfs->fw_priv)
189		err = do_firmware_uevent(fw_sysfs, env);
190	mutex_unlock(&fw_lock);
191	return err;
192}
193
194static struct class firmware_class = {
195	.name		= "firmware",
196	.class_groups	= firmware_class_groups,
197	.dev_uevent	= firmware_uevent,
198	.dev_release	= fw_dev_release,
199};
200
201int register_sysfs_loader(void)
202{
203	return class_register(&firmware_class);
204}
205
206void unregister_sysfs_loader(void)
207{
208	class_unregister(&firmware_class);
209}
210
211static ssize_t firmware_loading_show(struct device *dev,
212				     struct device_attribute *attr, char *buf)
213{
214	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
215	int loading = 0;
216
217	mutex_lock(&fw_lock);
218	if (fw_sysfs->fw_priv)
219		loading = fw_sysfs_loading(fw_sysfs->fw_priv);
220	mutex_unlock(&fw_lock);
221
222	return sprintf(buf, "%d\n", loading);
223}
224
225/**
226 * firmware_loading_store() - set value in the 'loading' control file
227 * @dev: device pointer
228 * @attr: device attribute pointer
229 * @buf: buffer to scan for loading control value
230 * @count: number of bytes in @buf
231 *
232 *	The relevant values are:
233 *
234 *	 1: Start a load, discarding any previous partial load.
235 *	 0: Conclude the load and hand the data to the driver code.
236 *	-1: Conclude the load with an error and discard any written data.
237 **/
238static ssize_t firmware_loading_store(struct device *dev,
239				      struct device_attribute *attr,
240				      const char *buf, size_t count)
241{
242	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
243	struct fw_priv *fw_priv;
244	ssize_t written = count;
245	int loading = simple_strtol(buf, NULL, 10);
246
247	mutex_lock(&fw_lock);
248	fw_priv = fw_sysfs->fw_priv;
249	if (fw_state_is_aborted(fw_priv))
250		goto out;
251
252	switch (loading) {
253	case 1:
254		/* discarding any previous partial load */
255		if (!fw_sysfs_done(fw_priv)) {
256			fw_free_paged_buf(fw_priv);
257			fw_state_start(fw_priv);
258		}
259		break;
260	case 0:
261		if (fw_sysfs_loading(fw_priv)) {
262			int rc;
263
264			/*
265			 * Several loading requests may be pending on
266			 * one same firmware buf, so let all requests
267			 * see the mapped 'buf->data' once the loading
268			 * is completed.
269			 * */
270			rc = fw_map_paged_buf(fw_priv);
271			if (rc)
272				dev_err(dev, "%s: map pages failed\n",
273					__func__);
274			else
275				rc = security_kernel_post_read_file(NULL,
276						fw_priv->data, fw_priv->size,
277						READING_FIRMWARE);
278
279			/*
280			 * Same logic as fw_load_abort, only the DONE bit
281			 * is ignored and we set ABORT only on failure.
282			 */
283			list_del_init(&fw_priv->pending_list);
284			if (rc) {
285				fw_state_aborted(fw_priv);
286				written = rc;
287			} else {
288				fw_state_done(fw_priv);
289			}
290			break;
291		}
292		fallthrough;
293	default:
294		dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
295		fallthrough;
296	case -1:
297		fw_load_abort(fw_sysfs);
298		break;
299	}
300out:
301	mutex_unlock(&fw_lock);
302	return written;
303}
304
305static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
306
307static void firmware_rw_data(struct fw_priv *fw_priv, char *buffer,
308			   loff_t offset, size_t count, bool read)
309{
310	if (read)
311		memcpy(buffer, fw_priv->data + offset, count);
312	else
313		memcpy(fw_priv->data + offset, buffer, count);
314}
315
316static void firmware_rw(struct fw_priv *fw_priv, char *buffer,
317			loff_t offset, size_t count, bool read)
318{
319	while (count) {
320		void *page_data;
321		int page_nr = offset >> PAGE_SHIFT;
322		int page_ofs = offset & (PAGE_SIZE-1);
323		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
324
325		page_data = kmap(fw_priv->pages[page_nr]);
326
327		if (read)
328			memcpy(buffer, page_data + page_ofs, page_cnt);
329		else
330			memcpy(page_data + page_ofs, buffer, page_cnt);
331
332		kunmap(fw_priv->pages[page_nr]);
333		buffer += page_cnt;
334		offset += page_cnt;
335		count -= page_cnt;
336	}
337}
338
339static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
340				  struct bin_attribute *bin_attr,
341				  char *buffer, loff_t offset, size_t count)
342{
343	struct device *dev = kobj_to_dev(kobj);
344	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
345	struct fw_priv *fw_priv;
346	ssize_t ret_count;
347
348	mutex_lock(&fw_lock);
349	fw_priv = fw_sysfs->fw_priv;
350	if (!fw_priv || fw_sysfs_done(fw_priv)) {
351		ret_count = -ENODEV;
352		goto out;
353	}
354	if (offset > fw_priv->size) {
355		ret_count = 0;
356		goto out;
357	}
358	if (count > fw_priv->size - offset)
359		count = fw_priv->size - offset;
360
361	ret_count = count;
362
363	if (fw_priv->data)
364		firmware_rw_data(fw_priv, buffer, offset, count, true);
365	else
366		firmware_rw(fw_priv, buffer, offset, count, true);
367
368out:
369	mutex_unlock(&fw_lock);
370	return ret_count;
371}
372
373static int fw_realloc_pages(struct fw_sysfs *fw_sysfs, int min_size)
374{
375	int err;
376
377	err = fw_grow_paged_buf(fw_sysfs->fw_priv,
378				PAGE_ALIGN(min_size) >> PAGE_SHIFT);
379	if (err)
380		fw_load_abort(fw_sysfs);
381	return err;
382}
383
384/**
385 * firmware_data_write() - write method for firmware
386 * @filp: open sysfs file
387 * @kobj: kobject for the device
388 * @bin_attr: bin_attr structure
389 * @buffer: buffer being written
390 * @offset: buffer offset for write in total data store area
391 * @count: buffer size
392 *
393 *	Data written to the 'data' attribute will be later handed to
394 *	the driver as a firmware image.
395 **/
396static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
397				   struct bin_attribute *bin_attr,
398				   char *buffer, loff_t offset, size_t count)
399{
400	struct device *dev = kobj_to_dev(kobj);
401	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
402	struct fw_priv *fw_priv;
403	ssize_t retval;
404
405	if (!capable(CAP_SYS_RAWIO))
406		return -EPERM;
407
408	mutex_lock(&fw_lock);
409	fw_priv = fw_sysfs->fw_priv;
410	if (!fw_priv || fw_sysfs_done(fw_priv)) {
411		retval = -ENODEV;
412		goto out;
413	}
414
415	if (fw_priv->data) {
416		if (offset + count > fw_priv->allocated_size) {
417			retval = -ENOMEM;
418			goto out;
419		}
420		firmware_rw_data(fw_priv, buffer, offset, count, false);
421		retval = count;
422	} else {
423		retval = fw_realloc_pages(fw_sysfs, offset + count);
424		if (retval)
425			goto out;
426
427		retval = count;
428		firmware_rw(fw_priv, buffer, offset, count, false);
429	}
430
431	fw_priv->size = max_t(size_t, offset + count, fw_priv->size);
432out:
433	mutex_unlock(&fw_lock);
434	return retval;
435}
436
437static struct bin_attribute firmware_attr_data = {
438	.attr = { .name = "data", .mode = 0644 },
439	.size = 0,
440	.read = firmware_data_read,
441	.write = firmware_data_write,
442};
443
444static struct attribute *fw_dev_attrs[] = {
445	&dev_attr_loading.attr,
446	NULL
447};
448
449static struct bin_attribute *fw_dev_bin_attrs[] = {
450	&firmware_attr_data,
451	NULL
452};
453
454static const struct attribute_group fw_dev_attr_group = {
455	.attrs = fw_dev_attrs,
456	.bin_attrs = fw_dev_bin_attrs,
457};
458
459static const struct attribute_group *fw_dev_attr_groups[] = {
460	&fw_dev_attr_group,
461	NULL
462};
463
464static struct fw_sysfs *
465fw_create_instance(struct firmware *firmware, const char *fw_name,
466		   struct device *device, u32 opt_flags)
467{
468	struct fw_sysfs *fw_sysfs;
469	struct device *f_dev;
470
471	fw_sysfs = kzalloc(sizeof(*fw_sysfs), GFP_KERNEL);
472	if (!fw_sysfs) {
473		fw_sysfs = ERR_PTR(-ENOMEM);
474		goto exit;
475	}
476
477	fw_sysfs->nowait = !!(opt_flags & FW_OPT_NOWAIT);
478	fw_sysfs->fw = firmware;
479	f_dev = &fw_sysfs->dev;
480
481	device_initialize(f_dev);
482	dev_set_name(f_dev, "%s", fw_name);
483	f_dev->parent = device;
484	f_dev->class = &firmware_class;
485	f_dev->groups = fw_dev_attr_groups;
486exit:
487	return fw_sysfs;
488}
489
490/**
491 * fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism
492 * @fw_sysfs: firmware sysfs information for the firmware to load
493 * @opt_flags: flags of options, FW_OPT_*
494 * @timeout: timeout to wait for the load
495 *
496 * In charge of constructing a sysfs fallback interface for firmware loading.
497 **/
498static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs,
499				  u32 opt_flags, long timeout)
500{
501	int retval = 0;
502	struct device *f_dev = &fw_sysfs->dev;
503	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
504
505	/* fall back on userspace loading */
506	if (!fw_priv->data)
507		fw_priv->is_paged_buf = true;
508
509	dev_set_uevent_suppress(f_dev, true);
510
511	retval = device_add(f_dev);
512	if (retval) {
513		dev_err(f_dev, "%s: device_register failed\n", __func__);
514		goto err_put_dev;
515	}
516
517	mutex_lock(&fw_lock);
518	list_add(&fw_priv->pending_list, &pending_fw_head);
519	mutex_unlock(&fw_lock);
520
521	if (opt_flags & FW_OPT_UEVENT) {
522		fw_priv->need_uevent = true;
523		dev_set_uevent_suppress(f_dev, false);
524		dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_name);
525		kobject_uevent(&fw_sysfs->dev.kobj, KOBJ_ADD);
526	} else {
527		timeout = MAX_JIFFY_OFFSET;
528	}
529
530	retval = fw_sysfs_wait_timeout(fw_priv, timeout);
531	if (retval < 0 && retval != -ENOENT) {
532		mutex_lock(&fw_lock);
533		fw_load_abort(fw_sysfs);
534		mutex_unlock(&fw_lock);
535	}
536
537	if (fw_state_is_aborted(fw_priv)) {
538		if (retval == -ERESTARTSYS)
539			retval = -EINTR;
540		else
541			retval = -EAGAIN;
542	} else if (fw_priv->is_paged_buf && !fw_priv->data)
543		retval = -ENOMEM;
544
545	device_del(f_dev);
546err_put_dev:
547	put_device(f_dev);
548	return retval;
549}
550
551static int fw_load_from_user_helper(struct firmware *firmware,
552				    const char *name, struct device *device,
553				    u32 opt_flags)
554{
555	struct fw_sysfs *fw_sysfs;
556	long timeout;
557	int ret;
558
559	timeout = firmware_loading_timeout();
560	if (opt_flags & FW_OPT_NOWAIT) {
561		timeout = usermodehelper_read_lock_wait(timeout);
562		if (!timeout) {
563			dev_dbg(device, "firmware: %s loading timed out\n",
564				name);
565			return -EBUSY;
566		}
567	} else {
568		ret = usermodehelper_read_trylock();
569		if (WARN_ON(ret)) {
570			dev_err(device, "firmware: %s will not be loaded\n",
571				name);
572			return ret;
573		}
574	}
575
576	fw_sysfs = fw_create_instance(firmware, name, device, opt_flags);
577	if (IS_ERR(fw_sysfs)) {
578		ret = PTR_ERR(fw_sysfs);
579		goto out_unlock;
580	}
581
582	fw_sysfs->fw_priv = firmware->priv;
583	ret = fw_load_sysfs_fallback(fw_sysfs, opt_flags, timeout);
584
585	if (!ret)
586		ret = assign_fw(firmware, device, opt_flags);
587
588out_unlock:
589	usermodehelper_read_unlock();
590
591	return ret;
592}
593
594static bool fw_force_sysfs_fallback(u32 opt_flags)
595{
596	if (fw_fallback_config.force_sysfs_fallback)
597		return true;
598	if (!(opt_flags & FW_OPT_USERHELPER))
599		return false;
600	return true;
601}
602
603static bool fw_run_sysfs_fallback(u32 opt_flags)
604{
605	int ret;
606
607	if (fw_fallback_config.ignore_sysfs_fallback) {
608		pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
609		return false;
610	}
611
612	if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS))
613		return false;
614
615	/* Also permit LSMs and IMA to fail firmware sysfs fallback */
616	ret = security_kernel_load_data(LOADING_FIRMWARE);
617	if (ret < 0)
618		return false;
619
620	return fw_force_sysfs_fallback(opt_flags);
621}
622
623/**
624 * firmware_fallback_sysfs() - use the fallback mechanism to find firmware
625 * @fw: pointer to firmware image
626 * @name: name of firmware file to look for
627 * @device: device for which firmware is being loaded
628 * @opt_flags: options to control firmware loading behaviour
629 * @ret: return value from direct lookup which triggered the fallback mechanism
630 *
631 * This function is called if direct lookup for the firmware failed, it enables
632 * a fallback mechanism through userspace by exposing a sysfs loading
633 * interface. Userspace is in charge of loading the firmware through the sysfs
634 * loading interface. This sysfs fallback mechanism may be disabled completely
635 * on a system by setting the proc sysctl value ignore_sysfs_fallback to true.
636 * If this is false we check if the internal API caller set the
637 * @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback
638 * mechanism. A system may want to enforce the sysfs fallback mechanism at all
639 * times, it can do this by setting ignore_sysfs_fallback to false and
640 * force_sysfs_fallback to true.
641 * Enabling force_sysfs_fallback is functionally equivalent to build a kernel
642 * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
643 **/
644int firmware_fallback_sysfs(struct firmware *fw, const char *name,
645			    struct device *device,
646			    u32 opt_flags,
647			    int ret)
648{
649	if (!fw_run_sysfs_fallback(opt_flags))
650		return ret;
651
652	if (!(opt_flags & FW_OPT_NO_WARN))
653		dev_warn(device, "Falling back to sysfs fallback for: %s\n",
654				 name);
655	else
656		dev_dbg(device, "Falling back to sysfs fallback for: %s\n",
657				name);
658	return fw_load_from_user_helper(fw, name, device, opt_flags);
659}