1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright(c) 2014 Intel Mobile Communications GmbH
4 * Copyright(c) 2015 Intel Deutschland GmbH
5 *
6 * Contact Information:
7 * Intel Linux Wireless <ilw@linux.intel.com>
8 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
9 *
10 * Author: Johannes Berg <johannes@sipsolutions.net>
11 */
12#include <linux/module.h>
13#include <linux/device.h>
14#include <linux/devcoredump.h>
15#include <linux/list.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18#include <linux/workqueue.h>
19
20static struct class devcd_class;
21
22/* global disable flag, for security purposes */
23static bool devcd_disabled;
24
25/* if data isn't read by userspace after 5 minutes then delete it */
26#define DEVCD_TIMEOUT (HZ * 60 * 5)
27
28struct devcd_entry {
29 struct device devcd_dev;
30 void *data;
31 size_t datalen;
32 struct module *owner;
33 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
34 void *data, size_t datalen);
35 void (*free)(void *data);
36 struct delayed_work del_wk;
37 struct device *failing_dev;
38};
39
40static struct devcd_entry *dev_to_devcd(struct device *dev)
41{
42 return container_of(dev, struct devcd_entry, devcd_dev);
43}
44
45static void devcd_dev_release(struct device *dev)
46{
47 struct devcd_entry *devcd = dev_to_devcd(dev);
48
49 devcd->free(devcd->data);
50 module_put(devcd->owner);
51
52 /*
53 * this seems racy, but I don't see a notifier or such on
54 * a struct device to know when it goes away?
55 */
56 if (devcd->failing_dev->kobj.sd)
57 sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
58 "devcoredump");
59
60 put_device(devcd->failing_dev);
61 kfree(devcd);
62}
63
64static void devcd_del(struct work_struct *wk)
65{
66 struct devcd_entry *devcd;
67
68 devcd = container_of(wk, struct devcd_entry, del_wk.work);
69
70 device_del(&devcd->devcd_dev);
71 put_device(&devcd->devcd_dev);
72}
73
74static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
75 struct bin_attribute *bin_attr,
76 char *buffer, loff_t offset, size_t count)
77{
78 struct device *dev = kobj_to_dev(kobj);
79 struct devcd_entry *devcd = dev_to_devcd(dev);
80
81 return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
82}
83
84static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
85 struct bin_attribute *bin_attr,
86 char *buffer, loff_t offset, size_t count)
87{
88 struct device *dev = kobj_to_dev(kobj);
89 struct devcd_entry *devcd = dev_to_devcd(dev);
90
91 mod_delayed_work(system_wq, &devcd->del_wk, 0);
92
93 return count;
94}
95
96static struct bin_attribute devcd_attr_data = {
97 .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
98 .size = 0,
99 .read = devcd_data_read,
100 .write = devcd_data_write,
101};
102
103static struct bin_attribute *devcd_dev_bin_attrs[] = {
104 &devcd_attr_data, NULL,
105};
106
107static const struct attribute_group devcd_dev_group = {
108 .bin_attrs = devcd_dev_bin_attrs,
109};
110
111static const struct attribute_group *devcd_dev_groups[] = {
112 &devcd_dev_group, NULL,
113};
114
115static int devcd_free(struct device *dev, void *data)
116{
117 struct devcd_entry *devcd = dev_to_devcd(dev);
118
119 flush_delayed_work(&devcd->del_wk);
120 return 0;
121}
122
123static ssize_t disabled_show(struct class *class, struct class_attribute *attr,
124 char *buf)
125{
126 return sprintf(buf, "%d\n", devcd_disabled);
127}
128
129static ssize_t disabled_store(struct class *class, struct class_attribute *attr,
130 const char *buf, size_t count)
131{
132 long tmp = simple_strtol(buf, NULL, 10);
133
134 /*
135 * This essentially makes the attribute write-once, since you can't
136 * go back to not having it disabled. This is intentional, it serves
137 * as a system lockdown feature.
138 */
139 if (tmp != 1)
140 return -EINVAL;
141
142 devcd_disabled = true;
143
144 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
145
146 return count;
147}
148static CLASS_ATTR_RW(disabled);
149
150static struct attribute *devcd_class_attrs[] = {
151 &class_attr_disabled.attr,
152 NULL,
153};
154ATTRIBUTE_GROUPS(devcd_class);
155
156static struct class devcd_class = {
157 .name = "devcoredump",
158 .owner = THIS_MODULE,
159 .dev_release = devcd_dev_release,
160 .dev_groups = devcd_dev_groups,
161 .class_groups = devcd_class_groups,
162};
163
164static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
165 void *data, size_t datalen)
166{
167 if (offset > datalen)
168 return -EINVAL;
169
170 if (offset + count > datalen)
171 count = datalen - offset;
172
173 if (count)
174 memcpy(buffer, ((u8 *)data) + offset, count);
175
176 return count;
177}
178
179static void devcd_freev(void *data)
180{
181 vfree(data);
182}
183
184/**
185 * dev_coredumpv - create device coredump with vmalloc data
186 * @dev: the struct device for the crashed device
187 * @data: vmalloc data containing the device coredump
188 * @datalen: length of the data
189 * @gfp: allocation flags
190 *
191 * This function takes ownership of the vmalloc'ed data and will free
192 * it when it is no longer used. See dev_coredumpm() for more information.
193 */
194void dev_coredumpv(struct device *dev, void *data, size_t datalen,
195 gfp_t gfp)
196{
197 dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
198}
199EXPORT_SYMBOL_GPL(dev_coredumpv);
200
201static int devcd_match_failing(struct device *dev, const void *failing)
202{
203 struct devcd_entry *devcd = dev_to_devcd(dev);
204
205 return devcd->failing_dev == failing;
206}
207
208/**
209 * devcd_free_sgtable - free all the memory of the given scatterlist table
210 * (i.e. both pages and scatterlist instances)
211 * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
212 * using the sg_chain function then that function should be called only once
213 * on the chained table
214 * @table: pointer to sg_table to free
215 */
216static void devcd_free_sgtable(void *data)
217{
218 _devcd_free_sgtable(data);
219}
220
221/**
222 * devcd_read_from_table - copy data from sg_table to a given buffer
223 * and return the number of bytes read
224 * @buffer: the buffer to copy the data to it
225 * @buf_len: the length of the buffer
226 * @data: the scatterlist table to copy from
227 * @offset: start copy from @offset@ bytes from the head of the data
228 * in the given scatterlist
229 * @data_len: the length of the data in the sg_table
230 */
231static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
232 size_t buf_len, void *data,
233 size_t data_len)
234{
235 struct scatterlist *table = data;
236
237 if (offset > data_len)
238 return -EINVAL;
239
240 if (offset + buf_len > data_len)
241 buf_len = data_len - offset;
242 return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
243 offset);
244}
245
246/**
247 * dev_coredumpm - create device coredump with read/free methods
248 * @dev: the struct device for the crashed device
249 * @owner: the module that contains the read/free functions, use %THIS_MODULE
250 * @data: data cookie for the @read/@free functions
251 * @datalen: length of the data
252 * @gfp: allocation flags
253 * @read: function to read from the given buffer
254 * @free: function to free the given buffer
255 *
256 * Creates a new device coredump for the given device. If a previous one hasn't
257 * been read yet, the new coredump is discarded. The data lifetime is determined
258 * by the device coredump framework and when it is no longer needed the @free
259 * function will be called to free the data.
260 */
261void dev_coredumpm(struct device *dev, struct module *owner,
262 void *data, size_t datalen, gfp_t gfp,
263 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
264 void *data, size_t datalen),
265 void (*free)(void *data))
266{
267 static atomic_t devcd_count = ATOMIC_INIT(0);
268 struct devcd_entry *devcd;
269 struct device *existing;
270
271 if (devcd_disabled)
272 goto free;
273
274 existing = class_find_device(&devcd_class, NULL, dev,
275 devcd_match_failing);
276 if (existing) {
277 put_device(existing);
278 goto free;
279 }
280
281 if (!try_module_get(owner))
282 goto free;
283
284 devcd = kzalloc(sizeof(*devcd), gfp);
285 if (!devcd)
286 goto put_module;
287
288 devcd->owner = owner;
289 devcd->data = data;
290 devcd->datalen = datalen;
291 devcd->read = read;
292 devcd->free = free;
293 devcd->failing_dev = get_device(dev);
294
295 device_initialize(&devcd->devcd_dev);
296
297 dev_set_name(&devcd->devcd_dev, "devcd%d",
298 atomic_inc_return(&devcd_count));
299 devcd->devcd_dev.class = &devcd_class;
300
301 if (device_add(&devcd->devcd_dev))
302 goto put_device;
303
304 if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
305 "failing_device"))
306 /* nothing - symlink will be missing */;
307
308 if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
309 "devcoredump"))
310 /* nothing - symlink will be missing */;
311
312 INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
313 schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
314
315 return;
316 put_device:
317 put_device(&devcd->devcd_dev);
318 put_module:
319 module_put(owner);
320 free:
321 free(data);
322}
323EXPORT_SYMBOL_GPL(dev_coredumpm);
324
325/**
326 * dev_coredumpmsg - create device coredump that uses scatterlist as data
327 * parameter
328 * @dev: the struct device for the crashed device
329 * @table: the dump data
330 * @datalen: length of the data
331 * @gfp: allocation flags
332 *
333 * Creates a new device coredump for the given device. If a previous one hasn't
334 * been read yet, the new coredump is discarded. The data lifetime is determined
335 * by the device coredump framework and when it is no longer needed
336 * it will free the data.
337 */
338void dev_coredumpsg(struct device *dev, struct scatterlist *table,
339 size_t datalen, gfp_t gfp)
340{
341 dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
342 devcd_free_sgtable);
343}
344EXPORT_SYMBOL_GPL(dev_coredumpsg);
345
346static int __init devcoredump_init(void)
347{
348 return class_register(&devcd_class);
349}
350__initcall(devcoredump_init);
351
352static void __exit devcoredump_exit(void)
353{
354 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
355 class_unregister(&devcd_class);
356}
357__exitcall(devcoredump_exit);
358