[mirror_ubuntu-jammy-kernel.git] / drivers / base / devcoredump.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright(c) 2014 Intel Mobile Communications GmbH
 * Copyright(c) 2015 Intel Deutschland GmbH
 *
 * 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 sysfs_emit(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)
{
	return memory_read_from_buffer(buffer, count, &offset, data, datalen);
}

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
 * @data: pointer to sg_table to free
 */
static void devcd_free_sgtable(void *data)
{
	_devcd_free_sgtable(data);
}

/**
 * devcd_read_from_sgtable - 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;

	/*
	 * These should normally not fail, but there is no problem
	 * continuing without the links, so just warn instead of
	 * failing.
	 */
	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
			      "failing_device") ||
	    sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
		              "devcoredump"))
		dev_warn(dev, "devcoredump create_link failed\n");

	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_coredumpsg - 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	* Author: Johannes Berg <johannes@sipsolutions.net>
	7	*/
	8	#include <linux/module.h>
	9	#include <linux/device.h>
	10	#include <linux/devcoredump.h>
	11	#include <linux/list.h>
	12	#include <linux/slab.h>
	13	#include <linux/fs.h>
	14	#include <linux/workqueue.h>
	15
d4533329 JB	16	static struct class devcd_class;
	17
	18	/* global disable flag, for security purposes */
	19	static bool devcd_disabled;
	20
833c9545 JB	21	/* if data isn't read by userspace after 5 minutes then delete it */
	22	#define DEVCD_TIMEOUT (HZ * 60 * 5)
	23
	24	struct devcd_entry {
	25	struct device devcd_dev;
52256637	26	void *data;
833c9545 JB	27	size_t datalen;
	28	struct module *owner;
	29	ssize_t (read)(char buffer, loff_t offset, size_t count,
52256637 AE	30	void *data, size_t datalen);
52256637 AE	31	void (free)(void data);
833c9545 JB	32	struct delayed_work del_wk;
	33	struct device *failing_dev;
	34	};
	35
	36	static struct devcd_entry dev_to_devcd(struct device dev)
	37	{
	38	return container_of(dev, struct devcd_entry, devcd_dev);
	39	}
	40
	41	static void devcd_dev_release(struct device *dev)
	42	{
	43	struct devcd_entry *devcd = dev_to_devcd(dev);
	44
	45	devcd->free(devcd->data);
	46	module_put(devcd->owner);
	47
	48	/*
	49	* this seems racy, but I don't see a notifier or such on
	50	* a struct device to know when it goes away?
	51	*/
	52	if (devcd->failing_dev->kobj.sd)
	53	sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
	54	"devcoredump");
	55
	56	put_device(devcd->failing_dev);
	57	kfree(devcd);
	58	}
	59
	60	static void devcd_del(struct work_struct *wk)
	61	{
	62	struct devcd_entry *devcd;
	63
	64	devcd = container_of(wk, struct devcd_entry, del_wk.work);
	65
	66	device_del(&devcd->devcd_dev);
	67	put_device(&devcd->devcd_dev);
	68	}
	69
	70	static ssize_t devcd_data_read(struct file filp, struct kobject kobj,
	71	struct bin_attribute *bin_attr,
	72	char *buffer, loff_t offset, size_t count)
	73	{
	74	struct device *dev = kobj_to_dev(kobj);
	75	struct devcd_entry *devcd = dev_to_devcd(dev);
	76
	77	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
	78	}
	79
	80	static ssize_t devcd_data_write(struct file filp, struct kobject kobj,
	81	struct bin_attribute *bin_attr,
	82	char *buffer, loff_t offset, size_t count)
	83	{
	84	struct device *dev = kobj_to_dev(kobj);
	85	struct devcd_entry *devcd = dev_to_devcd(dev);
	86
	87	mod_delayed_work(system_wq, &devcd->del_wk, 0);
	88
	89	return count;
	90	}
	91
	92	static struct bin_attribute devcd_attr_data = {
	93	.attr = { .name = "data", .mode = S_IRUSR \| S_IWUSR, },
	94	.size = 0,
	95	.read = devcd_data_read,
96	.write = devcd_data_write,
97	};
98
99	static struct bin_attribute *devcd_dev_bin_attrs[] = {
100	&devcd_attr_data, NULL,
101	};
102
103	static const struct attribute_group devcd_dev_group = {
104	.bin_attrs = devcd_dev_bin_attrs,
105	};
106
107	static const struct attribute_group *devcd_dev_groups[] = {
108	&devcd_dev_group, NULL,
109	};
110
d4533329 JB	111	static int devcd_free(struct device dev, void data)
	112	{
	113	struct devcd_entry *devcd = dev_to_devcd(dev);
	114
	115	flush_delayed_work(&devcd->del_wk);
	116	return 0;
	117	}
	118
	119	static ssize_t disabled_show(struct class class, struct class_attribute attr,
	120	char *buf)
	121	{
948b3edb	122	return sysfs_emit(buf, "%d\n", devcd_disabled);
d4533329 JB	123	}
	124
	125	static ssize_t disabled_store(struct class class, struct class_attribute attr,
	126	const char *buf, size_t count)
	127	{
	128	long tmp = simple_strtol(buf, NULL, 10);
	129
	130	/*
	131	* This essentially makes the attribute write-once, since you can't
	132	* go back to not having it disabled. This is intentional, it serves
	133	* as a system lockdown feature.
	134	*/
	135	if (tmp != 1)
	136	return -EINVAL;
	137
	138	devcd_disabled = true;
	139
	140	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	141
	142	return count;
	143	}
f76d2527	144	static CLASS_ATTR_RW(disabled);
d4533329	145
f76d2527 GKH	146	static struct attribute *devcd_class_attrs[] = {
	147	&class_attr_disabled.attr,
	148	NULL,
d4533329	149	};
f76d2527	150	ATTRIBUTE_GROUPS(devcd_class);
d4533329	151
833c9545 JB	152	static struct class devcd_class = {
	153	.name = "devcoredump",
	154	.owner = THIS_MODULE,
	155	.dev_release = devcd_dev_release,
	156	.dev_groups = devcd_dev_groups,
f76d2527	157	.class_groups = devcd_class_groups,
833c9545 JB	158	};
	159
	160	static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
52256637	161	void *data, size_t datalen)
833c9545	162	{
ce684d95	163	return memory_read_from_buffer(buffer, count, &offset, data, datalen);
833c9545 JB	164	}
833c9545 JB	165
52256637 AE	166	static void devcd_freev(void *data)
	167	{
	168	vfree(data);
	169	}
	170
833c9545 JB	171	/**
	172	* dev_coredumpv - create device coredump with vmalloc data
	173	* @dev: the struct device for the crashed device
	174	* @data: vmalloc data containing the device coredump
	175	* @datalen: length of the data
	176	* @gfp: allocation flags
	177	*
	178	* This function takes ownership of the vmalloc'ed data and will free
	179	* it when it is no longer used. See dev_coredumpm() for more information.
	180	*/
52256637	181	void dev_coredumpv(struct device dev, void data, size_t datalen,
833c9545 JB	182	gfp_t gfp)
833c9545 JB	183	{
52256637	184	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
833c9545 JB	185	}
	186	EXPORT_SYMBOL_GPL(dev_coredumpv);
	187
	188	static int devcd_match_failing(struct device dev, const void failing)
	189	{
	190	struct devcd_entry *devcd = dev_to_devcd(dev);
	191
	192	return devcd->failing_dev == failing;
	193	}
	194
52256637 AE	195	/**
	196	* devcd_free_sgtable - free all the memory of the given scatterlist table
	197	* (i.e. both pages and scatterlist instances)
	198	* NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
	199	* using the sg_chain function then that function should be called only once
	200	* on the chained table
cc710790	201	* @data: pointer to sg_table to free
52256637 AE	202	*/
	203	static void devcd_free_sgtable(void *data)
	204	{
	205	_devcd_free_sgtable(data);
	206	}
	207
	208	/**
cc710790	209	* devcd_read_from_sgtable - copy data from sg_table to a given buffer
52256637 AE	210	* and return the number of bytes read
	211	* @buffer: the buffer to copy the data to it
	212	* @buf_len: the length of the buffer
	213	* @data: the scatterlist table to copy from
	214	* @offset: start copy from @offset@ bytes from the head of the data
	215	* in the given scatterlist
	216	* @data_len: the length of the data in the sg_table
	217	*/
	218	static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
	219	size_t buf_len, void *data,
	220	size_t data_len)
	221	{
	222	struct scatterlist *table = data;
	223
	224	if (offset > data_len)
	225	return -EINVAL;
	226
	227	if (offset + buf_len > data_len)
	228	buf_len = data_len - offset;
	229	return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
	230	offset);
	231	}
	232
833c9545 JB	233	/**
	234	* dev_coredumpm - create device coredump with read/free methods
	235	* @dev: the struct device for the crashed device
	236	* @owner: the module that contains the read/free functions, use %THIS_MODULE
	237	* @data: data cookie for the @read/@free functions
	238	* @datalen: length of the data
	239	* @gfp: allocation flags
	240	* @read: function to read from the given buffer
	241	* @free: function to free the given buffer
	242	*
	243	* Creates a new device coredump for the given device. If a previous one hasn't
	244	* been read yet, the new coredump is discarded. The data lifetime is determined
	245	* by the device coredump framework and when it is no longer needed the @free
	246	* function will be called to free the data.
	247	*/
	248	void dev_coredumpm(struct device dev, struct module owner,
52256637	249	void *data, size_t datalen, gfp_t gfp,
833c9545	250	ssize_t (read)(char buffer, loff_t offset, size_t count,
52256637 AE	251	void *data, size_t datalen),
52256637 AE	252	void (free)(void data))
833c9545 JB	253	{
	254	static atomic_t devcd_count = ATOMIC_INIT(0);
	255	struct devcd_entry *devcd;
	256	struct device *existing;
	257
d4533329 JB	258	if (devcd_disabled)
	259	goto free;
	260
833c9545 JB	261	existing = class_find_device(&devcd_class, NULL, dev,
	262	devcd_match_failing);
	263	if (existing) {
	264	put_device(existing);
	265	goto free;
	266	}
	267
	268	if (!try_module_get(owner))
	269	goto free;
	270
	271	devcd = kzalloc(sizeof(*devcd), gfp);
	272	if (!devcd)
	273	goto put_module;
	274
	275	devcd->owner = owner;
	276	devcd->data = data;
	277	devcd->datalen = datalen;
	278	devcd->read = read;
	279	devcd->free = free;
	280	devcd->failing_dev = get_device(dev);
	281
	282	device_initialize(&devcd->devcd_dev);
	283
	284	dev_set_name(&devcd->devcd_dev, "devcd%d",
	285	atomic_inc_return(&devcd_count));
	286	devcd->devcd_dev.class = &devcd_class;
	287
	288	if (device_add(&devcd->devcd_dev))
	289	goto put_device;
	290
53f95c55 AB	291	/*
	292	* These should normally not fail, but there is no problem
	293	* continuing without the links, so just warn instead of
	294	* failing.
	295	*/
833c9545	296	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
53f95c55 AB	297	"failing_device") \|\|
	298	sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
	299	"devcoredump"))
	300	dev_warn(dev, "devcoredump create_link failed\n");
833c9545 JB	301
	302	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
	303	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
	304
	305	return;
	306	put_device:
	307	put_device(&devcd->devcd_dev);
	308	put_module:
	309	module_put(owner);
	310	free:
	311	free(data);
	312	}
	313	EXPORT_SYMBOL_GPL(dev_coredumpm);
	314
52256637	315	/**
2a77eec0	316	* dev_coredumpsg - create device coredump that uses scatterlist as data
52256637 AE	317	* parameter
	318	* @dev: the struct device for the crashed device
	319	* @table: the dump data
	320	* @datalen: length of the data
	321	* @gfp: allocation flags
	322	*
	323	* Creates a new device coredump for the given device. If a previous one hasn't
	324	* been read yet, the new coredump is discarded. The data lifetime is determined
	325	* by the device coredump framework and when it is no longer needed
	326	* it will free the data.
	327	*/
	328	void dev_coredumpsg(struct device dev, struct scatterlist table,
	329	size_t datalen, gfp_t gfp)
	330	{
	331	dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
	332	devcd_free_sgtable);
	333	}
	334	EXPORT_SYMBOL_GPL(dev_coredumpsg);
	335
833c9545 JB	336	static int __init devcoredump_init(void)
	337	{
	338	return class_register(&devcd_class);
	339	}
	340	__initcall(devcoredump_init);
	341
833c9545 JB	342	static void __exit devcoredump_exit(void)
	343	{
	344	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	345	class_unregister(&devcd_class);
	346	}
	347	__exitcall(devcoredump_exit);