[linux-2.6-block.git] / drivers / base / devcoredump.c

/*
 * This file is provided under the GPLv2 license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2014 Intel Mobile Communications GmbH
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * The full GNU General Public License is included in this distribution
 * in the file called COPYING.
 *
 * 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;
	const void *data;
	size_t datalen;
	struct module *owner;
	ssize_t (*read)(char *buffer, loff_t offset, size_t count,
			const void *data, size_t datalen);
	void (*free)(const 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 struct class_attribute devcd_class_attrs[] = {
	__ATTR_RW(disabled),
	__ATTR_NULL
};

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

static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
			   const 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;
}

/**
 * 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, const void *data, size_t datalen,
		   gfp_t gfp)
{
	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
}
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;
}

/**
 * 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,
		   const void *data, size_t datalen, gfp_t gfp,
		   ssize_t (*read)(char *buffer, loff_t offset, size_t count,
				   const void *data, size_t datalen),
		   void (*free)(const 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);

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
833c9545 JB	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	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of version 2 of the GNU General Public License as
	10	* published by the Free Software Foundation.
	11	*
	12	* This program is distributed in the hope that it will be useful, but
	13	* WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* General Public License for more details.
	16	*
	17	* The full GNU General Public License is included in this distribution
	18	* in the file called COPYING.
	19	*
	20	* Contact Information:
	21	* Intel Linux Wireless <ilw@linux.intel.com>
	22	* Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
	23	*
	24	* Author: Johannes Berg <johannes@sipsolutions.net>
	25	*/
	26	#include <linux/module.h>
	27	#include <linux/device.h>
	28	#include <linux/devcoredump.h>
	29	#include <linux/list.h>
	30	#include <linux/slab.h>
	31	#include <linux/fs.h>
	32	#include <linux/workqueue.h>
	33
d4533329 JB	34	static struct class devcd_class;
	35
	36	/* global disable flag, for security purposes */
	37	static bool devcd_disabled;
	38
833c9545 JB	39	/* if data isn't read by userspace after 5 minutes then delete it */
	40	#define DEVCD_TIMEOUT (HZ * 60 * 5)
	41
	42	struct devcd_entry {
	43	struct device devcd_dev;
	44	const void *data;
	45	size_t datalen;
	46	struct module *owner;
	47	ssize_t (read)(char buffer, loff_t offset, size_t count,
	48	const void *data, size_t datalen);
	49	void (free)(const void data);
	50	struct delayed_work del_wk;
	51	struct device *failing_dev;
	52	};
	53
	54	static struct devcd_entry dev_to_devcd(struct device dev)
	55	{
	56	return container_of(dev, struct devcd_entry, devcd_dev);
	57	}
	58
	59	static void devcd_dev_release(struct device *dev)
	60	{
	61	struct devcd_entry *devcd = dev_to_devcd(dev);
	62
	63	devcd->free(devcd->data);
	64	module_put(devcd->owner);
	65
	66	/*
	67	* this seems racy, but I don't see a notifier or such on
	68	* a struct device to know when it goes away?
	69	*/
	70	if (devcd->failing_dev->kobj.sd)
	71	sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
	72	"devcoredump");
	73
	74	put_device(devcd->failing_dev);
	75	kfree(devcd);
	76	}
	77
	78	static void devcd_del(struct work_struct *wk)
	79	{
	80	struct devcd_entry *devcd;
	81
	82	devcd = container_of(wk, struct devcd_entry, del_wk.work);
	83
	84	device_del(&devcd->devcd_dev);
	85	put_device(&devcd->devcd_dev);
	86	}
	87
	88	static ssize_t devcd_data_read(struct file filp, struct kobject kobj,
	89	struct bin_attribute *bin_attr,
	90	char *buffer, loff_t offset, size_t count)
	91	{
	92	struct device *dev = kobj_to_dev(kobj);
	93	struct devcd_entry *devcd = dev_to_devcd(dev);
	94
	95	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
	96	}
	97
	98	static ssize_t devcd_data_write(struct file filp, struct kobject kobj,
	99	struct bin_attribute *bin_attr,
	100	char *buffer, loff_t offset, size_t count)
	101	{
	102	struct device *dev = kobj_to_dev(kobj);
103	struct devcd_entry *devcd = dev_to_devcd(dev);
104
105	mod_delayed_work(system_wq, &devcd->del_wk, 0);
106
107	return count;
108	}
109
110	static struct bin_attribute devcd_attr_data = {
111	.attr = { .name = "data", .mode = S_IRUSR \| S_IWUSR, },
112	.size = 0,
113	.read = devcd_data_read,
114	.write = devcd_data_write,
115	};
116
117	static struct bin_attribute *devcd_dev_bin_attrs[] = {
118	&devcd_attr_data, NULL,
119	};
120
121	static const struct attribute_group devcd_dev_group = {
122	.bin_attrs = devcd_dev_bin_attrs,
123	};
124
125	static const struct attribute_group *devcd_dev_groups[] = {
126	&devcd_dev_group, NULL,
127	};
128
d4533329 JB	129	static int devcd_free(struct device dev, void data)
	130	{
	131	struct devcd_entry *devcd = dev_to_devcd(dev);
	132
	133	flush_delayed_work(&devcd->del_wk);
	134	return 0;
	135	}
	136
	137	static ssize_t disabled_show(struct class class, struct class_attribute attr,
	138	char *buf)
	139	{
	140	return sprintf(buf, "%d\n", devcd_disabled);
	141	}
	142
	143	static ssize_t disabled_store(struct class class, struct class_attribute attr,
	144	const char *buf, size_t count)
	145	{
	146	long tmp = simple_strtol(buf, NULL, 10);
	147
	148	/*
	149	* This essentially makes the attribute write-once, since you can't
	150	* go back to not having it disabled. This is intentional, it serves
	151	* as a system lockdown feature.
	152	*/
	153	if (tmp != 1)
	154	return -EINVAL;
	155
	156	devcd_disabled = true;
	157
	158	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	159
	160	return count;
	161	}
	162
	163	static struct class_attribute devcd_class_attrs[] = {
	164	__ATTR_RW(disabled),
	165	__ATTR_NULL
	166	};
	167
833c9545 JB	168	static struct class devcd_class = {
	169	.name = "devcoredump",
	170	.owner = THIS_MODULE,
	171	.dev_release = devcd_dev_release,
	172	.dev_groups = devcd_dev_groups,
d4533329	173	.class_attrs = devcd_class_attrs,
833c9545 JB	174	};
	175
	176	static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
	177	const void *data, size_t datalen)
	178	{
	179	if (offset > datalen)
	180	return -EINVAL;
	181
	182	if (offset + count > datalen)
	183	count = datalen - offset;
	184
	185	if (count)
	186	memcpy(buffer, ((u8 *)data) + offset, count);
	187
	188	return count;
	189	}
	190
	191	/**
	192	* dev_coredumpv - create device coredump with vmalloc data
	193	* @dev: the struct device for the crashed device
	194	* @data: vmalloc data containing the device coredump
	195	* @datalen: length of the data
	196	* @gfp: allocation flags
	197	*
	198	* This function takes ownership of the vmalloc'ed data and will free
	199	* it when it is no longer used. See dev_coredumpm() for more information.
	200	*/
	201	void dev_coredumpv(struct device dev, const void data, size_t datalen,
	202	gfp_t gfp)
	203	{
	204	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
	205	}
	206	EXPORT_SYMBOL_GPL(dev_coredumpv);
	207
	208	static int devcd_match_failing(struct device dev, const void failing)
	209	{
	210	struct devcd_entry *devcd = dev_to_devcd(dev);
	211
	212	return devcd->failing_dev == failing;
	213	}
	214
	215	/**
	216	* dev_coredumpm - create device coredump with read/free methods
	217	* @dev: the struct device for the crashed device
	218	* @owner: the module that contains the read/free functions, use %THIS_MODULE
	219	* @data: data cookie for the @read/@free functions
	220	* @datalen: length of the data
	221	* @gfp: allocation flags
	222	* @read: function to read from the given buffer
	223	* @free: function to free the given buffer
	224	*
	225	* Creates a new device coredump for the given device. If a previous one hasn't
	226	* been read yet, the new coredump is discarded. The data lifetime is determined
	227	* by the device coredump framework and when it is no longer needed the @free
	228	* function will be called to free the data.
	229	*/
	230	void dev_coredumpm(struct device dev, struct module owner,
	231	const void *data, size_t datalen, gfp_t gfp,
	232	ssize_t (read)(char buffer, loff_t offset, size_t count,
	233	const void *data, size_t datalen),
	234	void (free)(const void data))
	235	{
	236	static atomic_t devcd_count = ATOMIC_INIT(0);
	237	struct devcd_entry *devcd;
238	struct device *existing;
239
d4533329 JB	240	if (devcd_disabled)
	241	goto free;
	242
833c9545 JB	243	existing = class_find_device(&devcd_class, NULL, dev,
	244	devcd_match_failing);
	245	if (existing) {
	246	put_device(existing);
	247	goto free;
	248	}
	249
	250	if (!try_module_get(owner))
	251	goto free;
	252
	253	devcd = kzalloc(sizeof(*devcd), gfp);
	254	if (!devcd)
	255	goto put_module;
	256
	257	devcd->owner = owner;
	258	devcd->data = data;
	259	devcd->datalen = datalen;
	260	devcd->read = read;
	261	devcd->free = free;
	262	devcd->failing_dev = get_device(dev);
	263
	264	device_initialize(&devcd->devcd_dev);
	265
	266	dev_set_name(&devcd->devcd_dev, "devcd%d",
	267	atomic_inc_return(&devcd_count));
	268	devcd->devcd_dev.class = &devcd_class;
	269
	270	if (device_add(&devcd->devcd_dev))
	271	goto put_device;
	272
	273	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
	274	"failing_device"))
	275	/* nothing - symlink will be missing */;
	276
	277	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
	278	"devcoredump"))
	279	/* nothing - symlink will be missing */;
	280
	281	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
	282	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
	283
	284	return;
	285	put_device:
	286	put_device(&devcd->devcd_dev);
	287	put_module:
	288	module_put(owner);
	289	free:
	290	free(data);
	291	}
	292	EXPORT_SYMBOL_GPL(dev_coredumpm);
	293
	294	static int __init devcoredump_init(void)
	295	{
	296	return class_register(&devcd_class);
	297	}
	298	__initcall(devcoredump_init);
	299
833c9545 JB	300	static void __exit devcoredump_exit(void)
	301	{
	302	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
	303	class_unregister(&devcd_class);
	304	}
	305	__exitcall(devcoredump_exit);