drivers/base/devcoredump.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright(c) 2014 Intel Mobile Communications GmbH
  * Copyright(c) 2015 Intel Deutschland GmbH
  *
  * Contact Information:
  *  Intel Linux Wireless <ilw@linux.intel.com>
  * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
  *
  * Author: Johannes Berg <johannes@sipsolutions.net>
  */
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/devcoredump.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/workqueue.h>

 static struct class devcd_class;

 /* global disable flag, for security purposes */
 static bool devcd_disabled;

 /* if data isn't read by userspace after 5 minutes then delete it */
 #define DEVCD_TIMEOUT	(HZ * 60 * 5)

 struct devcd_entry {
 	struct device devcd_dev;
 	void *data;
 	size_t datalen;
 	struct module *owner;
 	ssize_t (*read)(char *buffer, loff_t offset, size_t count,
 			void *data, size_t datalen);
 	void (*free)(void *data);
 	struct delayed_work del_wk;
 	struct device *failing_dev;
 };

 static struct devcd_entry *dev_to_devcd(struct device *dev)
 {
 	return container_of(dev, struct devcd_entry, devcd_dev);
 }

 static void devcd_dev_release(struct device *dev)
 {
 	struct devcd_entry *devcd = dev_to_devcd(dev);

 	devcd->free(devcd->data);
 	module_put(devcd->owner);

 	/*
 	 * this seems racy, but I don't see a notifier or such on
 	 * a struct device to know when it goes away?
 	 */
 	if (devcd->failing_dev->kobj.sd)
 		sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
 				  "devcoredump");

 	put_device(devcd->failing_dev);
 	kfree(devcd);
 }

 static void devcd_del(struct work_struct *wk)
 {
 	struct devcd_entry *devcd;

 	devcd = container_of(wk, struct devcd_entry, del_wk.work);

 	device_del(&devcd->devcd_dev);
 	put_device(&devcd->devcd_dev);
 }

 static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
 			       struct bin_attribute *bin_attr,
 			       char *buffer, loff_t offset, size_t count)
 {
 	struct device *dev = kobj_to_dev(kobj);
 	struct devcd_entry *devcd = dev_to_devcd(dev);

 	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
 }

 static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
 				struct bin_attribute *bin_attr,
 				char *buffer, loff_t offset, size_t count)
 {
 	struct device *dev = kobj_to_dev(kobj);
 	struct devcd_entry *devcd = dev_to_devcd(dev);

 	mod_delayed_work(system_wq, &devcd->del_wk, 0);

 	return count;
 }

 static struct bin_attribute devcd_attr_data = {
 	.attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
 	.size = 0,
 	.read = devcd_data_read,
 	.write = devcd_data_write,
 };

 static struct bin_attribute *devcd_dev_bin_attrs[] = {
 	&devcd_attr_data, NULL,
 };

 static const struct attribute_group devcd_dev_group = {
 	.bin_attrs = devcd_dev_bin_attrs,
 };

 static const struct attribute_group *devcd_dev_groups[] = {
 	&devcd_dev_group, NULL,
 };

 static int devcd_free(struct device *dev, void *data)
 {
 	struct devcd_entry *devcd = dev_to_devcd(dev);

 	flush_delayed_work(&devcd->del_wk);
 	return 0;
 }

 static ssize_t disabled_show(struct class *class, struct class_attribute *attr,
 			     char *buf)
 {
 	return sprintf(buf, "%d\n", devcd_disabled);
 }

 static ssize_t disabled_store(struct class *class, struct class_attribute *attr,
 			      const char *buf, size_t count)
 {
 	long tmp = simple_strtol(buf, NULL, 10);

 	/*
 	 * This essentially makes the attribute write-once, since you can't
 	 * go back to not having it disabled. This is intentional, it serves
 	 * as a system lockdown feature.
 	 */
 	if (tmp != 1)
 		return -EINVAL;

 	devcd_disabled = true;

 	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);

 	return count;
 }
 static CLASS_ATTR_RW(disabled);

 static struct attribute *devcd_class_attrs[] = {
 	&class_attr_disabled.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(devcd_class);

 static struct class devcd_class = {
 	.name		= "devcoredump",
 	.owner		= THIS_MODULE,
 	.dev_release	= devcd_dev_release,
 	.dev_groups	= devcd_dev_groups,
 	.class_groups	= devcd_class_groups,
 };

 static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
 			   void *data, size_t datalen)
 {
 	if (offset > datalen)
 		return -EINVAL;

 	if (offset + count > datalen)
 		count = datalen - offset;

 	if (count)
 		memcpy(buffer, ((u8 *)data) + offset, count);

 	return count;
 }

 static void devcd_freev(void *data)
 {
 	vfree(data);
 }

 /**
  * dev_coredumpv - create device coredump with vmalloc data
  * @dev: the struct device for the crashed device
  * @data: vmalloc data containing the device coredump
  * @datalen: length of the data
  * @gfp: allocation flags
  *
  * This function takes ownership of the vmalloc'ed data and will free
  * it when it is no longer used. See dev_coredumpm() for more information.
  */
 void dev_coredumpv(struct device *dev, void *data, size_t datalen,
 		   gfp_t gfp)
 {
 	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
 }
 EXPORT_SYMBOL_GPL(dev_coredumpv);

 static int devcd_match_failing(struct device *dev, const void *failing)
 {
 	struct devcd_entry *devcd = dev_to_devcd(dev);

 	return devcd->failing_dev == failing;
 }

 /**
  * devcd_free_sgtable - free all the memory of the given scatterlist table
  * (i.e. both pages and scatterlist instances)
  * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
  * using the sg_chain function then that function should be called only once
  * on the chained table
  * @table: pointer to sg_table to free
  */
 static void devcd_free_sgtable(void *data)
 {
 	_devcd_free_sgtable(data);
 }

 /**
  * devcd_read_from_table - copy data from sg_table to a given buffer
  * and return the number of bytes read
  * @buffer: the buffer to copy the data to it
  * @buf_len: the length of the buffer
  * @data: the scatterlist table to copy from
  * @offset: start copy from @offset@ bytes from the head of the data
  *	in the given scatterlist
  * @data_len: the length of the data in the sg_table
  */
 static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
 				       size_t buf_len, void *data,
 				       size_t data_len)
 {
 	struct scatterlist *table = data;

 	if (offset > data_len)
 		return -EINVAL;

 	if (offset + buf_len > data_len)
 		buf_len = data_len - offset;
 	return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
 				  offset);
 }

 /**
  * dev_coredumpm - create device coredump with read/free methods
  * @dev: the struct device for the crashed device
  * @owner: the module that contains the read/free functions, use %THIS_MODULE
  * @data: data cookie for the @read/@free functions
  * @datalen: length of the data
  * @gfp: allocation flags
  * @read: function to read from the given buffer
  * @free: function to free the given buffer
  *
  * Creates a new device coredump for the given device. If a previous one hasn't
  * been read yet, the new coredump is discarded. The data lifetime is determined
  * by the device coredump framework and when it is no longer needed the @free
  * function will be called to free the data.
  */
 void dev_coredumpm(struct device *dev, struct module *owner,
 		   void *data, size_t datalen, gfp_t gfp,
 		   ssize_t (*read)(char *buffer, loff_t offset, size_t count,
 				   void *data, size_t datalen),
 		   void (*free)(void *data))
 {
 	static atomic_t devcd_count = ATOMIC_INIT(0);
 	struct devcd_entry *devcd;
 	struct device *existing;

 	if (devcd_disabled)
 		goto free;

 	existing = class_find_device(&devcd_class, NULL, dev,
 				     devcd_match_failing);
 	if (existing) {
 		put_device(existing);
 		goto free;
 	}

 	if (!try_module_get(owner))
 		goto free;

 	devcd = kzalloc(sizeof(*devcd), gfp);
 	if (!devcd)
 		goto put_module;

 	devcd->owner = owner;
 	devcd->data = data;
 	devcd->datalen = datalen;
 	devcd->read = read;
 	devcd->free = free;
 	devcd->failing_dev = get_device(dev);

 	device_initialize(&devcd->devcd_dev);

 	dev_set_name(&devcd->devcd_dev, "devcd%d",
 		     atomic_inc_return(&devcd_count));
 	devcd->devcd_dev.class = &devcd_class;

 	if (device_add(&devcd->devcd_dev))
 		goto put_device;

 	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
 			      "failing_device"))
 		/* nothing - symlink will be missing */;

 	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
 			      "devcoredump"))
 		/* nothing - symlink will be missing */;

 	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
 	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);

 	return;
  put_device:
 	put_device(&devcd->devcd_dev);
  put_module:
 	module_put(owner);
  free:
 	free(data);
 }
 EXPORT_SYMBOL_GPL(dev_coredumpm);

 /**
  * dev_coredumpmsg - create device coredump that uses scatterlist as data
  * parameter
  * @dev: the struct device for the crashed device
  * @table: the dump data
  * @datalen: length of the data
  * @gfp: allocation flags
  *
  * Creates a new device coredump for the given device. If a previous one hasn't
  * been read yet, the new coredump is discarded. The data lifetime is determined
  * by the device coredump framework and when it is no longer needed
  * it will free the data.
  */
 void dev_coredumpsg(struct device *dev, struct scatterlist *table,
 		    size_t datalen, gfp_t gfp)
 {
 	dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
 		      devcd_free_sgtable);
 }
 EXPORT_SYMBOL_GPL(dev_coredumpsg);

 static int __init devcoredump_init(void)
 {
 	return class_register(&devcd_class);
 }
 __initcall(devcoredump_init);

 static void __exit devcoredump_exit(void)
 {
 	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
 	class_unregister(&devcd_class);
 }
 __exitcall(devcoredump_exit);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright(c) 2014 Intel Mobile Communications GmbH
	* Copyright(c) 2015 Intel Deutschland GmbH
	*
	* Contact Information:
	* Intel Linux Wireless <ilw@linux.intel.com>
	* Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
	*
	* Author: Johannes Berg <johannes@sipsolutions.net>
	*/
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/devcoredump.h>
	#include <linux/list.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/workqueue.h>

	static struct class devcd_class;

	/* global disable flag, for security purposes */
	static bool devcd_disabled;

	/* if data isn't read by userspace after 5 minutes then delete it */
	#define DEVCD_TIMEOUT (HZ * 60 * 5)

	struct devcd_entry {
	struct device devcd_dev;
	void *data;
	size_t datalen;
	struct module *owner;
	ssize_t (read)(char buffer, loff_t offset, size_t count,
	void *data, size_t datalen);
	void (free)(void data);
	struct delayed_work del_wk;
	struct device *failing_dev;
	};

	static struct devcd_entry dev_to_devcd(struct device dev)
	{
	return container_of(dev, struct devcd_entry, devcd_dev);
	}

	static void devcd_dev_release(struct device *dev)
	{
	struct devcd_entry *devcd = dev_to_devcd(dev);

	devcd->free(devcd->data);
	module_put(devcd->owner);

	/*
	* this seems racy, but I don't see a notifier or such on
	* a struct device to know when it goes away?
	*/
	if (devcd->failing_dev->kobj.sd)
	sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
	"devcoredump");

	put_device(devcd->failing_dev);
	kfree(devcd);
	}

	static void devcd_del(struct work_struct *wk)
	{
	struct devcd_entry *devcd;

	devcd = container_of(wk, struct devcd_entry, del_wk.work);

	device_del(&devcd->devcd_dev);
	put_device(&devcd->devcd_dev);
	}

	static ssize_t devcd_data_read(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buffer, loff_t offset, size_t count)
	{
	struct device *dev = kobj_to_dev(kobj);
	struct devcd_entry *devcd = dev_to_devcd(dev);

	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
	}

	static ssize_t devcd_data_write(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buffer, loff_t offset, size_t count)
	{
	struct device *dev = kobj_to_dev(kobj);
	struct devcd_entry *devcd = dev_to_devcd(dev);

	mod_delayed_work(system_wq, &devcd->del_wk, 0);

	return count;
	}

	static struct bin_attribute devcd_attr_data = {
	.attr = { .name = "data", .mode = S_IRUSR \| S_IWUSR, },
	.size = 0,
	.read = devcd_data_read,
	.write = devcd_data_write,
	};

	static struct bin_attribute *devcd_dev_bin_attrs[] = {
	&devcd_attr_data, NULL,
	};

	static const struct attribute_group devcd_dev_group = {
	.bin_attrs = devcd_dev_bin_attrs,
	};

	static const struct attribute_group *devcd_dev_groups[] = {
	&devcd_dev_group, NULL,
	};

	static int devcd_free(struct device dev, void data)
	{
	struct devcd_entry *devcd = dev_to_devcd(dev);

	flush_delayed_work(&devcd->del_wk);
	return 0;
	}

	static ssize_t disabled_show(struct class class, struct class_attribute attr,
	char *buf)
	{
	return sprintf(buf, "%d\n", devcd_disabled);
	}

	static ssize_t disabled_store(struct class class, struct class_attribute attr,
	const char *buf, size_t count)
	{
	long tmp = simple_strtol(buf, NULL, 10);

	/*
	* This essentially makes the attribute write-once, since you can't
	* go back to not having it disabled. This is intentional, it serves
	* as a system lockdown feature.
	*/
	if (tmp != 1)
	return -EINVAL;

	devcd_disabled = true;

	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);

	return count;
	}
	static CLASS_ATTR_RW(disabled);

	static struct attribute *devcd_class_attrs[] = {
	&class_attr_disabled.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(devcd_class);

	static struct class devcd_class = {
	.name = "devcoredump",
	.owner = THIS_MODULE,
	.dev_release = devcd_dev_release,
	.dev_groups = devcd_dev_groups,
	.class_groups = devcd_class_groups,
	};

	static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
	void *data, size_t datalen)
	{
	if (offset > datalen)
	return -EINVAL;

	if (offset + count > datalen)
	count = datalen - offset;

	if (count)
	memcpy(buffer, ((u8 *)data) + offset, count);

	return count;
	}

	static void devcd_freev(void *data)
	{
	vfree(data);
	}

	/**
	* dev_coredumpv - create device coredump with vmalloc data
	* @dev: the struct device for the crashed device
	* @data: vmalloc data containing the device coredump
	* @datalen: length of the data
	* @gfp: allocation flags
	*
	* This function takes ownership of the vmalloc'ed data and will free
	* it when it is no longer used. See dev_coredumpm() for more information.
	*/
	void dev_coredumpv(struct device dev, void data, size_t datalen,
	gfp_t gfp)
	{
	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
	}
	EXPORT_SYMBOL_GPL(dev_coredumpv);

	static int devcd_match_failing(struct device dev, const void failing)
	{
	struct devcd_entry *devcd = dev_to_devcd(dev);

	return devcd->failing_dev == failing;
	}

	/**
	* devcd_free_sgtable - free all the memory of the given scatterlist table
	* (i.e. both pages and scatterlist instances)
	* NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
	* using the sg_chain function then that function should be called only once
	* on the chained table
	* @table: pointer to sg_table to free
	*/
	static void devcd_free_sgtable(void *data)
	{
	_devcd_free_sgtable(data);
	}

	/**
	* devcd_read_from_table - copy data from sg_table to a given buffer
	* and return the number of bytes read
	* @buffer: the buffer to copy the data to it
	* @buf_len: the length of the buffer
	* @data: the scatterlist table to copy from
	* @offset: start copy from @offset@ bytes from the head of the data
	* in the given scatterlist
	* @data_len: the length of the data in the sg_table
	*/
	static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
	size_t buf_len, void *data,
	size_t data_len)
	{
	struct scatterlist *table = data;

	if (offset > data_len)
	return -EINVAL;

	if (offset + buf_len > data_len)
	buf_len = data_len - offset;
	return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
	offset);
	}

	/**
	* dev_coredumpm - create device coredump with read/free methods
	* @dev: the struct device for the crashed device
	* @owner: the module that contains the read/free functions, use %THIS_MODULE
	* @data: data cookie for the @read/@free functions
	* @datalen: length of the data
	* @gfp: allocation flags
	* @read: function to read from the given buffer
	* @free: function to free the given buffer
	*
	* Creates a new device coredump for the given device. If a previous one hasn't
	* been read yet, the new coredump is discarded. The data lifetime is determined
	* by the device coredump framework and when it is no longer needed the @free
	* function will be called to free the data.
	*/
	void dev_coredumpm(struct device dev, struct module owner,
	void *data, size_t datalen, gfp_t gfp,
	ssize_t (read)(char buffer, loff_t offset, size_t count,
	void *data, size_t datalen),
	void (free)(void data))
	{
	static atomic_t devcd_count = ATOMIC_INIT(0);
	struct devcd_entry *devcd;
	struct device *existing;

	if (devcd_disabled)
	goto free;

	existing = class_find_device(&devcd_class, NULL, dev,
	devcd_match_failing);
	if (existing) {
	put_device(existing);
	goto free;
	}

	if (!try_module_get(owner))
	goto free;

	devcd = kzalloc(sizeof(*devcd), gfp);
	if (!devcd)
	goto put_module;

	devcd->owner = owner;
	devcd->data = data;
	devcd->datalen = datalen;
	devcd->read = read;
	devcd->free = free;
	devcd->failing_dev = get_device(dev);

	device_initialize(&devcd->devcd_dev);

	dev_set_name(&devcd->devcd_dev, "devcd%d",
	atomic_inc_return(&devcd_count));
	devcd->devcd_dev.class = &devcd_class;

	if (device_add(&devcd->devcd_dev))
	goto put_device;

	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
	"failing_device"))
	/* nothing - symlink will be missing */;

	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
	"devcoredump"))
	/* nothing - symlink will be missing */;

	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);

	return;
	put_device:
	put_device(&devcd->devcd_dev);
	put_module:
	module_put(owner);
	free:
	free(data);
	}
	EXPORT_SYMBOL_GPL(dev_coredumpm);

	/**
	* dev_coredumpmsg - create device coredump that uses scatterlist as data
	* parameter
	* @dev: the struct device for the crashed device
	* @table: the dump data
	* @datalen: length of the data
	* @gfp: allocation flags
	*
	* Creates a new device coredump for the given device. If a previous one hasn't
	* been read yet, the new coredump is discarded. The data lifetime is determined
	* by the device coredump framework and when it is no longer needed
	* it will free the data.
	*/
	void dev_coredumpsg(struct device dev, struct scatterlist table,
	size_t datalen, gfp_t gfp)
	{
	dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
	devcd_free_sgtable);
	}
	EXPORT_SYMBOL_GPL(dev_coredumpsg);

	static int __init devcoredump_init(void)
	{
	return class_register(&devcd_class);
	}
	__initcall(devcoredump_init);

	static void __exit devcoredump_exit(void)
	{
	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	class_unregister(&devcd_class);
	}
	__exitcall(devcoredump_exit);