drivers/base/devcoredump.c

   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
  35 static struct class devcd_class;
  36
  37 /* global disable flag, for security purposes */
  38 static 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
  43 struct 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
  55 static struct devcd_entry *dev_to_devcd(struct device *dev)
  56 {
  57         return container_of(dev, struct devcd_entry, devcd_dev);
  58 }
  59
  60 static 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
  79 static 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
  89 static 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
  99 static 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
 111 static 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
 118 static struct bin_attribute *devcd_dev_bin_attrs[] = {
 119         &devcd_attr_data, NULL,
 120 };
 121
 122 static const struct attribute_group devcd_dev_group = {
 123         .bin_attrs = devcd_dev_bin_attrs,
 124 };
 125
 126 static const struct attribute_group *devcd_dev_groups[] = {
 127         &devcd_dev_group, NULL,
 128 };
 129
 130 static 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
 138 static 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
 144 static 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 }
 163
 164 static struct class_attribute devcd_class_attrs[] = {
 165         __ATTR_RW(disabled),
 166         __ATTR_NULL
 167 };
 168
 169 static struct class devcd_class = {
 170         .name           = "devcoredump",
 171         .owner          = THIS_MODULE,
 172         .dev_release    = devcd_dev_release,
 173         .dev_groups     = devcd_dev_groups,
 174         .class_attrs    = devcd_class_attrs,
 175 };
 176
 177 static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
 178                            void *data, size_t datalen)
 179 {
 180         if (offset > datalen)
 181                 return -EINVAL;
 182
 183         if (offset + count > datalen)
 184                 count = datalen - offset;
 185
 186         if (count)
 187                 memcpy(buffer, ((u8 *)data) + offset, count);
 188
 189         return count;
 190 }
 191
 192 static void devcd_freev(void *data)
 193 {
 194         vfree(data);
 195 }
 196
 197 /**
 198  * dev_coredumpv - create device coredump with vmalloc data
 199  * @dev: the struct device for the crashed device
 200  * @data: vmalloc data containing the device coredump
 201  * @datalen: length of the data
 202  * @gfp: allocation flags
 203  *
 204  * This function takes ownership of the vmalloc'ed data and will free
 205  * it when it is no longer used. See dev_coredumpm() for more information.
 206  */
 207 void dev_coredumpv(struct device *dev, void *data, size_t datalen,
 208                    gfp_t gfp)
 209 {
 210         dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
 211 }
 212 EXPORT_SYMBOL_GPL(dev_coredumpv);
 213
 214 static int devcd_match_failing(struct device *dev, const void *failing)
 215 {
 216         struct devcd_entry *devcd = dev_to_devcd(dev);
 217
 218         return devcd->failing_dev == failing;
 219 }
 220
 221 /**
 222  * devcd_free_sgtable - free all the memory of the given scatterlist table
 223  * (i.e. both pages and scatterlist instances)
 224  * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
 225  * using the sg_chain function then that function should be called only once
 226  * on the chained table
 227  * @table: pointer to sg_table to free
 228  */
 229 static void devcd_free_sgtable(void *data)
 230 {
 231         _devcd_free_sgtable(data);
 232 }
 233
 234 /**
 235  * devcd_read_from_table - copy data from sg_table to a given buffer
 236  * and return the number of bytes read
 237  * @buffer: the buffer to copy the data to it
 238  * @buf_len: the length of the buffer
 239  * @data: the scatterlist table to copy from
 240  * @offset: start copy from @offset@ bytes from the head of the data
 241  *      in the given scatterlist
 242  * @data_len: the length of the data in the sg_table
 243  */
 244 static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
 245                                        size_t buf_len, void *data,
 246                                        size_t data_len)
 247 {
 248         struct scatterlist *table = data;
 249
 250         if (offset > data_len)
 251                 return -EINVAL;
 252
 253         if (offset + buf_len > data_len)
 254                 buf_len = data_len - offset;
 255         return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
 256                                   offset);
 257 }
 258
 259 /**
 260  * dev_coredumpm - create device coredump with read/free methods
 261  * @dev: the struct device for the crashed device
 262  * @owner: the module that contains the read/free functions, use %THIS_MODULE
 263  * @data: data cookie for the @read/@free functions
 264  * @datalen: length of the data
 265  * @gfp: allocation flags
 266  * @read: function to read from the given buffer
 267  * @free: function to free the given buffer
 268  *
 269  * Creates a new device coredump for the given device. If a previous one hasn't
 270  * been read yet, the new coredump is discarded. The data lifetime is determined
 271  * by the device coredump framework and when it is no longer needed the @free
 272  * function will be called to free the data.
 273  */
 274 void dev_coredumpm(struct device *dev, struct module *owner,
 275                    void *data, size_t datalen, gfp_t gfp,
 276                    ssize_t (*read)(char *buffer, loff_t offset, size_t count,
 277                                    void *data, size_t datalen),
 278                    void (*free)(void *data))
 279 {
 280         static atomic_t devcd_count = ATOMIC_INIT(0);
 281         struct devcd_entry *devcd;
 282         struct device *existing;
 283
 284         if (devcd_disabled)
 285                 goto free;
 286
 287         existing = class_find_device(&devcd_class, NULL, dev,
 288                                      devcd_match_failing);
 289         if (existing) {
 290                 put_device(existing);
 291                 goto free;
 292         }
 293
 294         if (!try_module_get(owner))
 295                 goto free;
 296
 297         devcd = kzalloc(sizeof(*devcd), gfp);
 298         if (!devcd)
 299                 goto put_module;
 300
 301         devcd->owner = owner;
 302         devcd->data = data;
 303         devcd->datalen = datalen;
 304         devcd->read = read;
 305         devcd->free = free;
 306         devcd->failing_dev = get_device(dev);
 307
 308         device_initialize(&devcd->devcd_dev);
 309
 310         dev_set_name(&devcd->devcd_dev, "devcd%d",
 311                      atomic_inc_return(&devcd_count));
 312         devcd->devcd_dev.class = &devcd_class;
 313
 314         if (device_add(&devcd->devcd_dev))
 315                 goto put_device;
 316
 317         if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
 318                               "failing_device"))
 319                 /* nothing - symlink will be missing */;
 320
 321         if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
 322                               "devcoredump"))
 323                 /* nothing - symlink will be missing */;
 324
 325         INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
 326         schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
 327
 328         return;
 329  put_device:
 330         put_device(&devcd->devcd_dev);
 331  put_module:
 332         module_put(owner);
 333  free:
 334         free(data);
 335 }
 336 EXPORT_SYMBOL_GPL(dev_coredumpm);
 337
 338 /**
 339  * dev_coredumpmsg - create device coredump that uses scatterlist as data
 340  * parameter
 341  * @dev: the struct device for the crashed device
 342  * @table: the dump data
 343  * @datalen: length of the data
 344  * @gfp: allocation flags
 345  *
 346  * Creates a new device coredump for the given device. If a previous one hasn't
 347  * been read yet, the new coredump is discarded. The data lifetime is determined
 348  * by the device coredump framework and when it is no longer needed
 349  * it will free the data.
 350  */
 351 void dev_coredumpsg(struct device *dev, struct scatterlist *table,
 352                     size_t datalen, gfp_t gfp)
 353 {
 354         dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
 355                       devcd_free_sgtable);
 356 }
 357 EXPORT_SYMBOL_GPL(dev_coredumpsg);
 358
 359 static int __init devcoredump_init(void)
 360 {
 361         return class_register(&devcd_class);
 362 }
 363 __initcall(devcoredump_init);
 364
 365 static void __exit devcoredump_exit(void)
 366 {
 367         class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
 368         class_unregister(&devcd_class);
 369 }
 370 __exitcall(devcoredump_exit);