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); 371