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 static CLASS_ATTR_RW(disabled);
 164
 165 static struct attribute *devcd_class_attrs[] = {
 166         &class_attr_disabled.attr,
 167         NULL,
 168 };
 169 ATTRIBUTE_GROUPS(devcd_class);
 170
 171 static 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
 179 static 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
 194 static 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  */
 209 void 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 }
 214 EXPORT_SYMBOL_GPL(dev_coredumpv);
 215
 216 static 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  */
 231 static 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  */
 246 static 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  */
 276 void 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 }
 338 EXPORT_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  */
 353 void 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 }
 359 EXPORT_SYMBOL_GPL(dev_coredumpsg);
 360
 361 static int __init devcoredump_init(void)
 362 {
 363         return class_register(&devcd_class);
 364 }
 365 __initcall(devcoredump_init);
 366
 367 static 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);