[linux.git] / drivers / base / devcoredump.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright(c) 2014 Intel Mobile Communications GmbH
 * Copyright(c) 2015 Intel Deutschland GmbH
 *
 * Contact Information:
 *  Intel Linux Wireless <[email protected]>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 * Author: Johannes Berg <[email protected]>
 */
#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);
Commit	Line	Data
989d42e8	1	// SPDX-License-Identifier: GPL-2.0
833c9545	2	/*
833c9545	3	* Copyright(c) 2014 Intel Mobile Communications GmbH
52256637	4	* Copyright(c) 2015 Intel Deutschland GmbH
833c9545	5	*
833c9545 JB	6	* Contact Information:
	7	* Intel Linux Wireless <[email protected]>
	8	* Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
	9	*
	10	* Author: Johannes Berg <[email protected]>
	11	*/
	12	#include <linux/module.h>
	13	#include <linux/device.h>
	14	#include <linux/devcoredump.h>
	15	#include <linux/list.h>
	16	#include <linux/slab.h>
	17	#include <linux/fs.h>
	18	#include <linux/workqueue.h>
	19
d4533329 JB	20	static struct class devcd_class;
	21
	22	/* global disable flag, for security purposes */
	23	static bool devcd_disabled;
	24
833c9545 JB	25	/* if data isn't read by userspace after 5 minutes then delete it */
	26	#define DEVCD_TIMEOUT (HZ * 60 * 5)
	27
	28	struct devcd_entry {
	29	struct device devcd_dev;
52256637	30	void *data;
833c9545 JB	31	size_t datalen;
	32	struct module *owner;
	33	ssize_t (read)(char buffer, loff_t offset, size_t count,
52256637 AE	34	void *data, size_t datalen);
52256637 AE	35	void (free)(void data);
833c9545 JB	36	struct delayed_work del_wk;
	37	struct device *failing_dev;
	38	};
	39
	40	static struct devcd_entry dev_to_devcd(struct device dev)
	41	{
	42	return container_of(dev, struct devcd_entry, devcd_dev);
	43	}
	44
	45	static void devcd_dev_release(struct device *dev)
	46	{
	47	struct devcd_entry *devcd = dev_to_devcd(dev);
	48
	49	devcd->free(devcd->data);
	50	module_put(devcd->owner);
	51
	52	/*
	53	* this seems racy, but I don't see a notifier or such on
	54	* a struct device to know when it goes away?
	55	*/
	56	if (devcd->failing_dev->kobj.sd)
	57	sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
	58	"devcoredump");
	59
	60	put_device(devcd->failing_dev);
	61	kfree(devcd);
	62	}
	63
	64	static void devcd_del(struct work_struct *wk)
	65	{
	66	struct devcd_entry *devcd;
	67
	68	devcd = container_of(wk, struct devcd_entry, del_wk.work);
	69
	70	device_del(&devcd->devcd_dev);
	71	put_device(&devcd->devcd_dev);
	72	}
	73
	74	static ssize_t devcd_data_read(struct file filp, struct kobject kobj,
	75	struct bin_attribute *bin_attr,
	76	char *buffer, loff_t offset, size_t count)
	77	{
	78	struct device *dev = kobj_to_dev(kobj);
	79	struct devcd_entry *devcd = dev_to_devcd(dev);
	80
	81	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
	82	}
	83
	84	static ssize_t devcd_data_write(struct file filp, struct kobject kobj,
	85	struct bin_attribute *bin_attr,
	86	char *buffer, loff_t offset, size_t count)
	87	{
	88	struct device *dev = kobj_to_dev(kobj);
	89	struct devcd_entry *devcd = dev_to_devcd(dev);
	90
	91	mod_delayed_work(system_wq, &devcd->del_wk, 0);
	92
	93	return count;
	94	}
	95
	96	static struct bin_attribute devcd_attr_data = {
	97	.attr = { .name = "data", .mode = S_IRUSR \| S_IWUSR, },
	98	.size = 0,
	99	.read = devcd_data_read,
100	.write = devcd_data_write,
101	};
102
103	static struct bin_attribute *devcd_dev_bin_attrs[] = {
104	&devcd_attr_data, NULL,
105	};
106
107	static const struct attribute_group devcd_dev_group = {
108	.bin_attrs = devcd_dev_bin_attrs,
109	};
110
111	static const struct attribute_group *devcd_dev_groups[] = {
112	&devcd_dev_group, NULL,
113	};
114
d4533329 JB	115	static int devcd_free(struct device dev, void data)
	116	{
	117	struct devcd_entry *devcd = dev_to_devcd(dev);
	118
	119	flush_delayed_work(&devcd->del_wk);
	120	return 0;
	121	}
	122
	123	static ssize_t disabled_show(struct class class, struct class_attribute attr,
	124	char *buf)
	125	{
	126	return sprintf(buf, "%d\n", devcd_disabled);
	127	}
	128
	129	static ssize_t disabled_store(struct class class, struct class_attribute attr,
	130	const char *buf, size_t count)
	131	{
	132	long tmp = simple_strtol(buf, NULL, 10);
	133
	134	/*
	135	* This essentially makes the attribute write-once, since you can't
	136	* go back to not having it disabled. This is intentional, it serves
	137	* as a system lockdown feature.
	138	*/
	139	if (tmp != 1)
	140	return -EINVAL;
	141
	142	devcd_disabled = true;
	143
	144	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	145
	146	return count;
	147	}
f76d2527	148	static CLASS_ATTR_RW(disabled);
d4533329	149
f76d2527 GKH	150	static struct attribute *devcd_class_attrs[] = {
	151	&class_attr_disabled.attr,
	152	NULL,
d4533329	153	};
f76d2527	154	ATTRIBUTE_GROUPS(devcd_class);
d4533329	155
833c9545 JB	156	static struct class devcd_class = {
	157	.name = "devcoredump",
	158	.owner = THIS_MODULE,
	159	.dev_release = devcd_dev_release,
	160	.dev_groups = devcd_dev_groups,
f76d2527	161	.class_groups = devcd_class_groups,
833c9545 JB	162	};
	163
	164	static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
52256637	165	void *data, size_t datalen)
833c9545 JB	166	{
	167	if (offset > datalen)
	168	return -EINVAL;
	169
	170	if (offset + count > datalen)
	171	count = datalen - offset;
	172
	173	if (count)
	174	memcpy(buffer, ((u8 *)data) + offset, count);
	175
	176	return count;
	177	}
	178
52256637 AE	179	static void devcd_freev(void *data)
	180	{
	181	vfree(data);
	182	}
	183
833c9545 JB	184	/**
	185	* dev_coredumpv - create device coredump with vmalloc data
	186	* @dev: the struct device for the crashed device
	187	* @data: vmalloc data containing the device coredump
	188	* @datalen: length of the data
	189	* @gfp: allocation flags
	190	*
	191	* This function takes ownership of the vmalloc'ed data and will free
	192	* it when it is no longer used. See dev_coredumpm() for more information.
	193	*/
52256637	194	void dev_coredumpv(struct device dev, void data, size_t datalen,
833c9545 JB	195	gfp_t gfp)
833c9545 JB	196	{
52256637	197	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
833c9545 JB	198	}
	199	EXPORT_SYMBOL_GPL(dev_coredumpv);
	200
	201	static int devcd_match_failing(struct device dev, const void failing)
	202	{
	203	struct devcd_entry *devcd = dev_to_devcd(dev);
	204
	205	return devcd->failing_dev == failing;
	206	}
	207
52256637 AE	208	/**
	209	* devcd_free_sgtable - free all the memory of the given scatterlist table
	210	* (i.e. both pages and scatterlist instances)
	211	* NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
	212	* using the sg_chain function then that function should be called only once
	213	* on the chained table
	214	* @table: pointer to sg_table to free
	215	*/
	216	static void devcd_free_sgtable(void *data)
	217	{
	218	_devcd_free_sgtable(data);
	219	}
	220
	221	/**
	222	* devcd_read_from_table - copy data from sg_table to a given buffer
	223	* and return the number of bytes read
	224	* @buffer: the buffer to copy the data to it
	225	* @buf_len: the length of the buffer
	226	* @data: the scatterlist table to copy from
	227	* @offset: start copy from @offset@ bytes from the head of the data
	228	* in the given scatterlist
	229	* @data_len: the length of the data in the sg_table
	230	*/
	231	static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
	232	size_t buf_len, void *data,
	233	size_t data_len)
	234	{
	235	struct scatterlist *table = data;
	236
	237	if (offset > data_len)
	238	return -EINVAL;
	239
	240	if (offset + buf_len > data_len)
	241	buf_len = data_len - offset;
	242	return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
	243	offset);
	244	}
	245
833c9545 JB	246	/**
	247	* dev_coredumpm - create device coredump with read/free methods
	248	* @dev: the struct device for the crashed device
	249	* @owner: the module that contains the read/free functions, use %THIS_MODULE
	250	* @data: data cookie for the @read/@free functions
	251	* @datalen: length of the data
	252	* @gfp: allocation flags
	253	* @read: function to read from the given buffer
	254	* @free: function to free the given buffer
	255	*
	256	* Creates a new device coredump for the given device. If a previous one hasn't
	257	* been read yet, the new coredump is discarded. The data lifetime is determined
	258	* by the device coredump framework and when it is no longer needed the @free
	259	* function will be called to free the data.
	260	*/
	261	void dev_coredumpm(struct device dev, struct module owner,
52256637	262	void *data, size_t datalen, gfp_t gfp,
833c9545	263	ssize_t (read)(char buffer, loff_t offset, size_t count,
52256637 AE	264	void *data, size_t datalen),
52256637 AE	265	void (free)(void data))
833c9545 JB	266	{
	267	static atomic_t devcd_count = ATOMIC_INIT(0);
	268	struct devcd_entry *devcd;
	269	struct device *existing;
	270
d4533329 JB	271	if (devcd_disabled)
	272	goto free;
	273
833c9545 JB	274	existing = class_find_device(&devcd_class, NULL, dev,
	275	devcd_match_failing);
	276	if (existing) {
	277	put_device(existing);
	278	goto free;
	279	}
	280
	281	if (!try_module_get(owner))
	282	goto free;
	283
	284	devcd = kzalloc(sizeof(*devcd), gfp);
	285	if (!devcd)
	286	goto put_module;
	287
	288	devcd->owner = owner;
	289	devcd->data = data;
	290	devcd->datalen = datalen;
	291	devcd->read = read;
	292	devcd->free = free;
	293	devcd->failing_dev = get_device(dev);
	294
	295	device_initialize(&devcd->devcd_dev);
	296
	297	dev_set_name(&devcd->devcd_dev, "devcd%d",
	298	atomic_inc_return(&devcd_count));
	299	devcd->devcd_dev.class = &devcd_class;
	300
	301	if (device_add(&devcd->devcd_dev))
	302	goto put_device;
	303
	304	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
	305	"failing_device"))
	306	/* nothing - symlink will be missing */;
	307
	308	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
	309	"devcoredump"))
	310	/* nothing - symlink will be missing */;
	311
	312	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
	313	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
	314
	315	return;
	316	put_device:
	317	put_device(&devcd->devcd_dev);
	318	put_module:
	319	module_put(owner);
	320	free:
	321	free(data);
	322	}
	323	EXPORT_SYMBOL_GPL(dev_coredumpm);
	324
52256637 AE	325	/**
	326	* dev_coredumpmsg - create device coredump that uses scatterlist as data
	327	* parameter
	328	* @dev: the struct device for the crashed device
	329	* @table: the dump data
	330	* @datalen: length of the data
	331	* @gfp: allocation flags
	332	*
	333	* Creates a new device coredump for the given device. If a previous one hasn't
	334	* been read yet, the new coredump is discarded. The data lifetime is determined
	335	* by the device coredump framework and when it is no longer needed
	336	* it will free the data.
	337	*/
	338	void dev_coredumpsg(struct device dev, struct scatterlist table,
	339	size_t datalen, gfp_t gfp)
	340	{
	341	dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
	342	devcd_free_sgtable);
	343	}
	344	EXPORT_SYMBOL_GPL(dev_coredumpsg);
	345
833c9545 JB	346	static int __init devcoredump_init(void)
	347	{
	348	return class_register(&devcd_class);
	349	}
	350	__initcall(devcoredump_init);
	351
833c9545 JB	352	static void __exit devcoredump_exit(void)
	353	{
	354	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	355	class_unregister(&devcd_class);
	356	}
	357	__exitcall(devcoredump_exit);