Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 428 insertions, 0 deletions

diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c
new file mode 100644
index 000000000..7e2d1f0d9
--- /dev/null
+++ b/drivers/base/devcoredump.c
@@ -0,0 +1,428 @@
+// 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);
+	dev_set_uevent_suppress(&devcd->devcd_dev, true);
+	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");
+
+	dev_set_uevent_suppress(&devcd->devcd_dev, false);
+	kobject_uevent(&devcd->devcd_dev.kobj, KOBJ_ADD);
+	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);