// 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);