1/*
  2 * This file is provided under the GPLv2 license.
  3 *
  4 * GPL LICENSE SUMMARY
  5 *
  6 * Copyright(c) 2014 Intel Mobile Communications GmbH
  7 * Copyright(c) 2015 Intel Deutschland GmbH
  8 *
  9 * This program is free software; you can redistribute it and/or modify
 10 * it under the terms of version 2 of the GNU General Public License as
 11 * published by the Free Software Foundation.
 12 *
 13 * This program is distributed in the hope that it will be useful, but
 14 * WITHOUT ANY WARRANTY; without even the implied warranty of
 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 16 * General Public License for more details.
 17 *
 18 * The full GNU General Public License is included in this distribution
 19 * in the file called COPYING.
 20 *
 21 * Contact Information:
 22 *  Intel Linux Wireless <ilw@linux.intel.com>
 23 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 24 *
 25 * Author: Johannes Berg <johannes@sipsolutions.net>
 26 */
 27#include <linux/module.h>
 28#include <linux/device.h>
 29#include <linux/devcoredump.h>
 30#include <linux/list.h>
 31#include <linux/slab.h>
 32#include <linux/fs.h>
 33#include <linux/workqueue.h>
 34
 35static struct class devcd_class;
 36
 37/* global disable flag, for security purposes */
 38static bool devcd_disabled;
 39
 40/* if data isn't read by userspace after 5 minutes then delete it */
 41#define DEVCD_TIMEOUT	(HZ * 60 * 5)
 42
 43struct devcd_entry {
 44	struct device devcd_dev;
 45	void *data;
 46	size_t datalen;
 47	struct module *owner;
 48	ssize_t (*read)(char *buffer, loff_t offset, size_t count,
 49			void *data, size_t datalen);
 50	void (*free)(void *data);
 51	struct delayed_work del_wk;
 52	struct device *failing_dev;
 53};
 54
 55static struct devcd_entry *dev_to_devcd(struct device *dev)
 56{
 57	return container_of(dev, struct devcd_entry, devcd_dev);
 58}
 59
 60static void devcd_dev_release(struct device *dev)
 61{
 62	struct devcd_entry *devcd = dev_to_devcd(dev);
 63
 64	devcd->free(devcd->data);
 65	module_put(devcd->owner);
 66
 67	/*
 68	 * this seems racy, but I don't see a notifier or such on
 69	 * a struct device to know when it goes away?
 70	 */
 71	if (devcd->failing_dev->kobj.sd)
 72		sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
 73				  "devcoredump");
 74
 75	put_device(devcd->failing_dev);
 76	kfree(devcd);
 77}
 78
 79static void devcd_del(struct work_struct *wk)
 80{
 81	struct devcd_entry *devcd;
 82
 83	devcd = container_of(wk, struct devcd_entry, del_wk.work);
 84
 85	device_del(&devcd->devcd_dev);
 86	put_device(&devcd->devcd_dev);
 87}
 88
 89static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
 90			       struct bin_attribute *bin_attr,
 91			       char *buffer, loff_t offset, size_t count)
 92{
 93	struct device *dev = kobj_to_dev(kobj);
 94	struct devcd_entry *devcd = dev_to_devcd(dev);
 95
 96	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
 97}
 98
 99static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
100				struct bin_attribute *bin_attr,
101				char *buffer, loff_t offset, size_t count)
102{
103	struct device *dev = kobj_to_dev(kobj);
104	struct devcd_entry *devcd = dev_to_devcd(dev);
105
106	mod_delayed_work(system_wq, &devcd->del_wk, 0);
107
108	return count;
109}
110
111static struct bin_attribute devcd_attr_data = {
112	.attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
113	.size = 0,
114	.read = devcd_data_read,
115	.write = devcd_data_write,
116};
117
118static struct bin_attribute *devcd_dev_bin_attrs[] = {
119	&devcd_attr_data, NULL,
120};
121
122static const struct attribute_group devcd_dev_group = {
123	.bin_attrs = devcd_dev_bin_attrs,
124};
125
126static const struct attribute_group *devcd_dev_groups[] = {
127	&devcd_dev_group, NULL,
128};
129
130static int devcd_free(struct device *dev, void *data)
131{
132	struct devcd_entry *devcd = dev_to_devcd(dev);
133
134	flush_delayed_work(&devcd->del_wk);
135	return 0;
136}
137
138static ssize_t disabled_show(struct class *class, struct class_attribute *attr,
139			     char *buf)
140{
141	return sprintf(buf, "%d\n", devcd_disabled);
142}
143
144static ssize_t disabled_store(struct class *class, struct class_attribute *attr,
145			      const char *buf, size_t count)
146{
147	long tmp = simple_strtol(buf, NULL, 10);
148
149	/*
150	 * This essentially makes the attribute write-once, since you can't
151	 * go back to not having it disabled. This is intentional, it serves
152	 * as a system lockdown feature.
153	 */
154	if (tmp != 1)
155		return -EINVAL;
156
157	devcd_disabled = true;
158
159	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
160
161	return count;
162}
163static CLASS_ATTR_RW(disabled);
164
165static struct attribute *devcd_class_attrs[] = {
166	&class_attr_disabled.attr,
167	NULL,
168};
169ATTRIBUTE_GROUPS(devcd_class);
170
171static struct class devcd_class = {
172	.name		= "devcoredump",
173	.owner		= THIS_MODULE,
174	.dev_release	= devcd_dev_release,
175	.dev_groups	= devcd_dev_groups,
176	.class_groups	= devcd_class_groups,
177};
178
179static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
180			   void *data, size_t datalen)
181{
182	if (offset > datalen)
183		return -EINVAL;
184
185	if (offset + count > datalen)
186		count = datalen - offset;
187
188	if (count)
189		memcpy(buffer, ((u8 *)data) + offset, count);
190
191	return count;
192}
193
194static void devcd_freev(void *data)
195{
196	vfree(data);
197}
198
199/**
200 * dev_coredumpv - create device coredump with vmalloc data
201 * @dev: the struct device for the crashed device
202 * @data: vmalloc data containing the device coredump
203 * @datalen: length of the data
204 * @gfp: allocation flags
205 *
206 * This function takes ownership of the vmalloc'ed data and will free
207 * it when it is no longer used. See dev_coredumpm() for more information.
208 */
209void dev_coredumpv(struct device *dev, void *data, size_t datalen,
210		   gfp_t gfp)
211{
212	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
213}
214EXPORT_SYMBOL_GPL(dev_coredumpv);
215
216static int devcd_match_failing(struct device *dev, const void *failing)
217{
218	struct devcd_entry *devcd = dev_to_devcd(dev);
219
220	return devcd->failing_dev == failing;
221}
222
223/**
224 * devcd_free_sgtable - free all the memory of the given scatterlist table
225 * (i.e. both pages and scatterlist instances)
226 * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
227 * using the sg_chain function then that function should be called only once
228 * on the chained table
229 * @table: pointer to sg_table to free
230 */
231static void devcd_free_sgtable(void *data)
232{
233	_devcd_free_sgtable(data);
234}
235
236/**
237 * devcd_read_from_table - copy data from sg_table to a given buffer
238 * and return the number of bytes read
239 * @buffer: the buffer to copy the data to it
240 * @buf_len: the length of the buffer
241 * @data: the scatterlist table to copy from
242 * @offset: start copy from @offset@ bytes from the head of the data
243 *	in the given scatterlist
244 * @data_len: the length of the data in the sg_table
245 */
246static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
247				       size_t buf_len, void *data,
248				       size_t data_len)
249{
250	struct scatterlist *table = data;
251
252	if (offset > data_len)
253		return -EINVAL;
254
255	if (offset + buf_len > data_len)
256		buf_len = data_len - offset;
257	return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
258				  offset);
259}
260
261/**
262 * dev_coredumpm - create device coredump with read/free methods
263 * @dev: the struct device for the crashed device
264 * @owner: the module that contains the read/free functions, use %THIS_MODULE
265 * @data: data cookie for the @read/@free functions
266 * @datalen: length of the data
267 * @gfp: allocation flags
268 * @read: function to read from the given buffer
269 * @free: function to free the given buffer
270 *
271 * Creates a new device coredump for the given device. If a previous one hasn't
272 * been read yet, the new coredump is discarded. The data lifetime is determined
273 * by the device coredump framework and when it is no longer needed the @free
274 * function will be called to free the data.
275 */
276void dev_coredumpm(struct device *dev, struct module *owner,
277		   void *data, size_t datalen, gfp_t gfp,
278		   ssize_t (*read)(char *buffer, loff_t offset, size_t count,
279				   void *data, size_t datalen),
280		   void (*free)(void *data))
281{
282	static atomic_t devcd_count = ATOMIC_INIT(0);
283	struct devcd_entry *devcd;
284	struct device *existing;
285
286	if (devcd_disabled)
287		goto free;
288
289	existing = class_find_device(&devcd_class, NULL, dev,
290				     devcd_match_failing);
291	if (existing) {
292		put_device(existing);
293		goto free;
294	}
295
296	if (!try_module_get(owner))
297		goto free;
298
299	devcd = kzalloc(sizeof(*devcd), gfp);
300	if (!devcd)
301		goto put_module;
302
303	devcd->owner = owner;
304	devcd->data = data;
305	devcd->datalen = datalen;
306	devcd->read = read;
307	devcd->free = free;
308	devcd->failing_dev = get_device(dev);
309
310	device_initialize(&devcd->devcd_dev);
311
312	dev_set_name(&devcd->devcd_dev, "devcd%d",
313		     atomic_inc_return(&devcd_count));
314	devcd->devcd_dev.class = &devcd_class;
315
316	if (device_add(&devcd->devcd_dev))
317		goto put_device;
318
319	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
320			      "failing_device"))
321		/* nothing - symlink will be missing */;
322
323	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
324			      "devcoredump"))
325		/* nothing - symlink will be missing */;
326
327	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
328	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
329
330	return;
331 put_device:
332	put_device(&devcd->devcd_dev);
333 put_module:
334	module_put(owner);
335 free:
336	free(data);
337}
338EXPORT_SYMBOL_GPL(dev_coredumpm);
339
340/**
341 * dev_coredumpmsg - create device coredump that uses scatterlist as data
342 * parameter
343 * @dev: the struct device for the crashed device
344 * @table: the dump data
345 * @datalen: length of the data
346 * @gfp: allocation flags
347 *
348 * Creates a new device coredump for the given device. If a previous one hasn't
349 * been read yet, the new coredump is discarded. The data lifetime is determined
350 * by the device coredump framework and when it is no longer needed
351 * it will free the data.
352 */
353void dev_coredumpsg(struct device *dev, struct scatterlist *table,
354		    size_t datalen, gfp_t gfp)
355{
356	dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
357		      devcd_free_sgtable);
358}
359EXPORT_SYMBOL_GPL(dev_coredumpsg);
360
361static int __init devcoredump_init(void)
362{
363	return class_register(&devcd_class);
364}
365__initcall(devcoredump_init);
366
367static void __exit devcoredump_exit(void)
368{
369	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
370	class_unregister(&devcd_class);
371}
372__exitcall(devcoredump_exit);