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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 return memory_read_from_buffer(buffer, count, &offset, data, datalen);
168}
169
170static void devcd_freev(void *data)
171{
172 vfree(data);
173}
174
175/**
176 * dev_coredumpv - create device coredump with vmalloc data
177 * @dev: the struct device for the crashed device
178 * @data: vmalloc data containing the device coredump
179 * @datalen: length of the data
180 * @gfp: allocation flags
181 *
182 * This function takes ownership of the vmalloc'ed data and will free
183 * it when it is no longer used. See dev_coredumpm() for more information.
184 */
185void dev_coredumpv(struct device *dev, void *data, size_t datalen,
186 gfp_t gfp)
187{
188 dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
189}
190EXPORT_SYMBOL_GPL(dev_coredumpv);
191
192static int devcd_match_failing(struct device *dev, const void *failing)
193{
194 struct devcd_entry *devcd = dev_to_devcd(dev);
195
196 return devcd->failing_dev == failing;
197}
198
199/**
200 * devcd_free_sgtable - free all the memory of the given scatterlist table
201 * (i.e. both pages and scatterlist instances)
202 * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
203 * using the sg_chain function then that function should be called only once
204 * on the chained table
205 * @table: pointer to sg_table to free
206 */
207static void devcd_free_sgtable(void *data)
208{
209 _devcd_free_sgtable(data);
210}
211
212/**
213 * devcd_read_from_table - copy data from sg_table to a given buffer
214 * and return the number of bytes read
215 * @buffer: the buffer to copy the data to it
216 * @buf_len: the length of the buffer
217 * @data: the scatterlist table to copy from
218 * @offset: start copy from @offset@ bytes from the head of the data
219 * in the given scatterlist
220 * @data_len: the length of the data in the sg_table
221 */
222static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
223 size_t buf_len, void *data,
224 size_t data_len)
225{
226 struct scatterlist *table = data;
227
228 if (offset > data_len)
229 return -EINVAL;
230
231 if (offset + buf_len > data_len)
232 buf_len = data_len - offset;
233 return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
234 offset);
235}
236
237/**
238 * dev_coredumpm - create device coredump with read/free methods
239 * @dev: the struct device for the crashed device
240 * @owner: the module that contains the read/free functions, use %THIS_MODULE
241 * @data: data cookie for the @read/@free functions
242 * @datalen: length of the data
243 * @gfp: allocation flags
244 * @read: function to read from the given buffer
245 * @free: function to free the given buffer
246 *
247 * Creates a new device coredump for the given device. If a previous one hasn't
248 * been read yet, the new coredump is discarded. The data lifetime is determined
249 * by the device coredump framework and when it is no longer needed the @free
250 * function will be called to free the data.
251 */
252void dev_coredumpm(struct device *dev, struct module *owner,
253 void *data, size_t datalen, gfp_t gfp,
254 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
255 void *data, size_t datalen),
256 void (*free)(void *data))
257{
258 static atomic_t devcd_count = ATOMIC_INIT(0);
259 struct devcd_entry *devcd;
260 struct device *existing;
261
262 if (devcd_disabled)
263 goto free;
264
265 existing = class_find_device(&devcd_class, NULL, dev,
266 devcd_match_failing);
267 if (existing) {
268 put_device(existing);
269 goto free;
270 }
271
272 if (!try_module_get(owner))
273 goto free;
274
275 devcd = kzalloc(sizeof(*devcd), gfp);
276 if (!devcd)
277 goto put_module;
278
279 devcd->owner = owner;
280 devcd->data = data;
281 devcd->datalen = datalen;
282 devcd->read = read;
283 devcd->free = free;
284 devcd->failing_dev = get_device(dev);
285
286 device_initialize(&devcd->devcd_dev);
287
288 dev_set_name(&devcd->devcd_dev, "devcd%d",
289 atomic_inc_return(&devcd_count));
290 devcd->devcd_dev.class = &devcd_class;
291
292 if (device_add(&devcd->devcd_dev))
293 goto put_device;
294
295 if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
296 "failing_device"))
297 /* nothing - symlink will be missing */;
298
299 if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
300 "devcoredump"))
301 /* nothing - symlink will be missing */;
302
303 INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
304 schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
305
306 return;
307 put_device:
308 put_device(&devcd->devcd_dev);
309 put_module:
310 module_put(owner);
311 free:
312 free(data);
313}
314EXPORT_SYMBOL_GPL(dev_coredumpm);
315
316/**
317 * dev_coredumpsg - create device coredump that uses scatterlist as data
318 * parameter
319 * @dev: the struct device for the crashed device
320 * @table: the dump data
321 * @datalen: length of the data
322 * @gfp: allocation flags
323 *
324 * Creates a new device coredump for the given device. If a previous one hasn't
325 * been read yet, the new coredump is discarded. The data lifetime is determined
326 * by the device coredump framework and when it is no longer needed
327 * it will free the data.
328 */
329void dev_coredumpsg(struct device *dev, struct scatterlist *table,
330 size_t datalen, gfp_t gfp)
331{
332 dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
333 devcd_free_sgtable);
334}
335EXPORT_SYMBOL_GPL(dev_coredumpsg);
336
337static int __init devcoredump_init(void)
338{
339 return class_register(&devcd_class);
340}
341__initcall(devcoredump_init);
342
343static void __exit devcoredump_exit(void)
344{
345 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
346 class_unregister(&devcd_class);
347}
348__exitcall(devcoredump_exit);