// 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; /* * Here, mutex is required to serialize the calls to del_wk work between * user/kernel space which happens when devcd is added with device_add() * and that sends uevent to user space. User space reads the uevents, * and calls to devcd_data_write() which try to modify the work which is * not even initialized/queued from devcoredump. * * * * cpu0(X) cpu1(Y) * * dev_coredump() uevent sent to user space * device_add() ======================> user space process Y reads the * uevents writes to devcd fd * which results into writes to * * devcd_data_write() * mod_delayed_work() * try_to_grab_pending() * del_timer() * debug_assert_init() * INIT_DELAYED_WORK() * schedule_delayed_work() * * * Also, mutex alone would not be enough to avoid scheduling of * del_wk work after it get flush from a call to devcd_free() * mentioned as below. * * disabled_store() * devcd_free() * mutex_lock() devcd_data_write() * flush_delayed_work() * mutex_unlock() * mutex_lock() * mod_delayed_work() * mutex_unlock() * So, delete_work flag is required. */ struct mutex mutex; bool delete_work; 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); mutex_lock(&devcd->mutex); if (!devcd->delete_work) { devcd->delete_work = true; mod_delayed_work(system_wq, &devcd->del_wk, 0); } mutex_unlock(&devcd->mutex); 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); mutex_lock(&devcd->mutex); if (!devcd->delete_work) devcd->delete_work = true; flush_delayed_work(&devcd->del_wk); mutex_unlock(&devcd->mutex); return 0;} static ssize_t disabled_show(const struct class *class, const struct class_attribute *attr, char *buf){ return sysfs_emit(buf, "%d\n", devcd_disabled);} /* * * disabled_store() worker() * class_for_each_device(&devcd_class, * NULL, NULL, devcd_free) * ... * ... * while ((dev = class_dev_iter_next(&iter)) * devcd_del() * device_del() * put_device() <- last reference * error = fn(dev, data) devcd_dev_release() * devcd_free(dev, data) kfree(devcd) * mutex_lock(&devcd->mutex); * * * In the above diagram, It looks like disabled_store() would be racing with parallely * running devcd_del() and result in memory abort while acquiring devcd->mutex which * is called after kfree of devcd memory after dropping its last reference with * put_device(). However, this will not happens as fn(dev, data) runs * with its own reference to device via klist_node so it is not its last reference. * so, above situation would not occur. */ static ssize_t disabled_store(const struct class *class, const 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", .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); devcd->delete_work = false; mutex_init(&devcd->mutex); device_initialize(&devcd->devcd_dev); dev_set_name(&devcd->devcd_dev, "devcd%d", atomic_inc_return(&devcd_count)); devcd->devcd_dev.class = &devcd_class; mutex_lock(&devcd->mutex); 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); mutex_unlock(&devcd->mutex); return; put_device: put_device(&devcd->devcd_dev); mutex_unlock(&devcd->mutex); 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);
// 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;
/*
* Here, mutex is required to serialize the calls to del_wk work between
* user/kernel space which happens when devcd is added with device_add()
* and that sends uevent to user space. User space reads the uevents,
* and calls to devcd_data_write() which try to modify the work which is
* not even initialized/queued from devcoredump.
*
*
*
* cpu0(X) cpu1(Y)
*
* dev_coredump() uevent sent to user space
* device_add() ======================> user space process Y reads the
* uevents writes to devcd fd
* which results into writes to
*
* devcd_data_write()
* mod_delayed_work()
* try_to_grab_pending()
* del_timer()
* debug_assert_init()
* INIT_DELAYED_WORK()
* schedule_delayed_work()
*
*
* Also, mutex alone would not be enough to avoid scheduling of
* del_wk work after it get flush from a call to devcd_free()
* mentioned as below.
*
* disabled_store()
* devcd_free()
* mutex_lock() devcd_data_write()
* flush_delayed_work()
* mutex_unlock()
* mutex_lock()
* mod_delayed_work()
* mutex_unlock()
* So, delete_work flag is required.
*/
struct mutex mutex;
bool delete_work;
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);
mutex_lock(&devcd->mutex);
if (!devcd->delete_work) {
devcd->delete_work = true;
mod_delayed_work(system_wq, &devcd->del_wk, 0);
}
mutex_unlock(&devcd->mutex);
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);
mutex_lock(&devcd->mutex);
if (!devcd->delete_work)
devcd->delete_work = true;
flush_delayed_work(&devcd->del_wk);
mutex_unlock(&devcd->mutex);
return 0;
}
static ssize_t disabled_show(const struct class *class, const struct class_attribute *attr,
char *buf)
{
return sysfs_emit(buf, "%d\n", devcd_disabled);
}
/*
*
* disabled_store() worker()
* class_for_each_device(&devcd_class,
* NULL, NULL, devcd_free)
* ...
* ...
* while ((dev = class_dev_iter_next(&iter))
* devcd_del()
* device_del()
* put_device() <- last reference
* error = fn(dev, data) devcd_dev_release()
* devcd_free(dev, data) kfree(devcd)
* mutex_lock(&devcd->mutex);
*
*
* In the above diagram, It looks like disabled_store() would be racing with parallely
* running devcd_del() and result in memory abort while acquiring devcd->mutex which
* is called after kfree of devcd memory after dropping its last reference with
* put_device(). However, this will not happens as fn(dev, data) runs
* with its own reference to device via klist_node so it is not its last reference.
* so, above situation would not occur.
*/
static ssize_t disabled_store(const struct class *class, const 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",
.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);
devcd->delete_work = false;
mutex_init(&devcd->mutex);
device_initialize(&devcd->devcd_dev);
dev_set_name(&devcd->devcd_dev, "devcd%d",
atomic_inc_return(&devcd_count));
devcd->devcd_dev.class = &devcd_class;
mutex_lock(&devcd->mutex);
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);
mutex_unlock(&devcd->mutex);
return;
put_device:
put_device(&devcd->devcd_dev);
mutex_unlock(&devcd->mutex);
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);