1 files changed, 661 insertions, 0 deletions

diff --git a/drivers/base/firmware_fallback.c b/drivers/base/firmware_fallback.c
new file mode 100644
index 000000000000..47690207e0ee
--- /dev/null
+++ b/drivers/base/firmware_fallback.c
@@ -0,0 +1,661 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/types.h>
+#include <linux/kconfig.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/highmem.h>
+#include <linux/umh.h>
+
+#include "firmware_fallback.h"
+#include "firmware_loader.h"
+
+/*
+ * firmware fallback mechanism
+ */
+
+extern struct firmware_fallback_config fw_fallback_config;
+
+/* These getters are vetted to use int properly */
+static inline int __firmware_loading_timeout(void)
+{
+	return fw_fallback_config.loading_timeout;
+}
+
+/* These setters are vetted to use int properly */
+static void __fw_fallback_set_timeout(int timeout)
+{
+	fw_fallback_config.loading_timeout = timeout;
+}
+
+/*
+ * use small loading timeout for caching devices' firmware because all these
+ * firmware images have been loaded successfully at lease once, also system is
+ * ready for completing firmware loading now. The maximum size of firmware in
+ * current distributions is about 2M bytes, so 10 secs should be enough.
+ */
+void fw_fallback_set_cache_timeout(void)
+{
+	fw_fallback_config.old_timeout = __firmware_loading_timeout();
+	__fw_fallback_set_timeout(10);
+}
+
+/* Restores the timeout to the value last configured during normal operation */
+void fw_fallback_set_default_timeout(void)
+{
+	__fw_fallback_set_timeout(fw_fallback_config.old_timeout);
+}
+
+static long firmware_loading_timeout(void)
+{
+	return __firmware_loading_timeout() > 0 ?
+		__firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
+}
+
+static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
+{
+	return __fw_state_check(fw_priv, FW_STATUS_DONE);
+}
+
+static inline bool fw_sysfs_loading(struct fw_priv *fw_priv)
+{
+	return __fw_state_check(fw_priv, FW_STATUS_LOADING);
+}
+
+static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv,  long timeout)
+{
+	return __fw_state_wait_common(fw_priv, timeout);
+}
+
+struct fw_sysfs {
+	bool nowait;
+	struct device dev;
+	struct fw_priv *fw_priv;
+	struct firmware *fw;
+};
+
+static struct fw_sysfs *to_fw_sysfs(struct device *dev)
+{
+	return container_of(dev, struct fw_sysfs, dev);
+}
+
+static void __fw_load_abort(struct fw_priv *fw_priv)
+{
+	/*
+	 * There is a small window in which user can write to 'loading'
+	 * between loading done and disappearance of 'loading'
+	 */
+	if (fw_sysfs_done(fw_priv))
+		return;
+
+	list_del_init(&fw_priv->pending_list);
+	fw_state_aborted(fw_priv);
+}
+
+static void fw_load_abort(struct fw_sysfs *fw_sysfs)
+{
+	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
+
+	__fw_load_abort(fw_priv);
+}
+
+static LIST_HEAD(pending_fw_head);
+
+void kill_pending_fw_fallback_reqs(bool only_kill_custom)
+{
+	struct fw_priv *fw_priv;
+	struct fw_priv *next;
+
+	mutex_lock(&fw_lock);
+	list_for_each_entry_safe(fw_priv, next, &pending_fw_head,
+				 pending_list) {
+		if (!fw_priv->need_uevent || !only_kill_custom)
+			 __fw_load_abort(fw_priv);
+	}
+	mutex_unlock(&fw_lock);
+}
+
+static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
+			    char *buf)
+{
+	return sprintf(buf, "%d\n", __firmware_loading_timeout());
+}
+
+/**
+ * firmware_timeout_store - set number of seconds to wait for firmware
+ * @class: device class pointer
+ * @attr: device attribute pointer
+ * @buf: buffer to scan for timeout value
+ * @count: number of bytes in @buf
+ *
+ *	Sets the number of seconds to wait for the firmware.  Once
+ *	this expires an error will be returned to the driver and no
+ *	firmware will be provided.
+ *
+ *	Note: zero means 'wait forever'.
+ **/
+static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
+			     const char *buf, size_t count)
+{
+	int tmp_loading_timeout = simple_strtol(buf, NULL, 10);
+
+	if (tmp_loading_timeout < 0)
+		tmp_loading_timeout = 0;
+
+	__fw_fallback_set_timeout(tmp_loading_timeout);
+
+	return count;
+}
+static CLASS_ATTR_RW(timeout);
+
+static struct attribute *firmware_class_attrs[] = {
+	&class_attr_timeout.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(firmware_class);
+
+static void fw_dev_release(struct device *dev)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+
+	kfree(fw_sysfs);
+}
+
+static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env *env)
+{
+	if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
+		return -ENOMEM;
+	if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
+		return -ENOMEM;
+	if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	int err = 0;
+
+	mutex_lock(&fw_lock);
+	if (fw_sysfs->fw_priv)
+		err = do_firmware_uevent(fw_sysfs, env);
+	mutex_unlock(&fw_lock);
+	return err;
+}
+
+static struct class firmware_class = {
+	.name		= "firmware",
+	.class_groups	= firmware_class_groups,
+	.dev_uevent	= firmware_uevent,
+	.dev_release	= fw_dev_release,
+};
+
+int register_sysfs_loader(void)
+{
+	return class_register(&firmware_class);
+}
+
+void unregister_sysfs_loader(void)
+{
+	class_unregister(&firmware_class);
+}
+
+static ssize_t firmware_loading_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	int loading = 0;
+
+	mutex_lock(&fw_lock);
+	if (fw_sysfs->fw_priv)
+		loading = fw_sysfs_loading(fw_sysfs->fw_priv);
+	mutex_unlock(&fw_lock);
+
+	return sprintf(buf, "%d\n", loading);
+}
+
+/* Some architectures don't have PAGE_KERNEL_RO */
+#ifndef PAGE_KERNEL_RO
+#define PAGE_KERNEL_RO PAGE_KERNEL
+#endif
+
+/* one pages buffer should be mapped/unmapped only once */
+static int map_fw_priv_pages(struct fw_priv *fw_priv)
+{
+	if (!fw_priv->is_paged_buf)
+		return 0;
+
+	vunmap(fw_priv->data);
+	fw_priv->data = vmap(fw_priv->pages, fw_priv->nr_pages, 0,
+			     PAGE_KERNEL_RO);
+	if (!fw_priv->data)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * firmware_loading_store - set value in the 'loading' control file
+ * @dev: device pointer
+ * @attr: device attribute pointer
+ * @buf: buffer to scan for loading control value
+ * @count: number of bytes in @buf
+ *
+ *	The relevant values are:
+ *
+ *	 1: Start a load, discarding any previous partial load.
+ *	 0: Conclude the load and hand the data to the driver code.
+ *	-1: Conclude the load with an error and discard any written data.
+ **/
+static ssize_t firmware_loading_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t written = count;
+	int loading = simple_strtol(buf, NULL, 10);
+	int i;
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (fw_state_is_aborted(fw_priv))
+		goto out;
+
+	switch (loading) {
+	case 1:
+		/* discarding any previous partial load */
+		if (!fw_sysfs_done(fw_priv)) {
+			for (i = 0; i < fw_priv->nr_pages; i++)
+				__free_page(fw_priv->pages[i]);
+			vfree(fw_priv->pages);
+			fw_priv->pages = NULL;
+			fw_priv->page_array_size = 0;
+			fw_priv->nr_pages = 0;
+			fw_state_start(fw_priv);
+		}
+		break;
+	case 0:
+		if (fw_sysfs_loading(fw_priv)) {
+			int rc;
+
+			/*
+			 * Several loading requests may be pending on
+			 * one same firmware buf, so let all requests
+			 * see the mapped 'buf->data' once the loading
+			 * is completed.
+			 * */
+			rc = map_fw_priv_pages(fw_priv);
+			if (rc)
+				dev_err(dev, "%s: map pages failed\n",
+					__func__);
+			else
+				rc = security_kernel_post_read_file(NULL,
+						fw_priv->data, fw_priv->size,
+						READING_FIRMWARE);
+
+			/*
+			 * Same logic as fw_load_abort, only the DONE bit
+			 * is ignored and we set ABORT only on failure.
+			 */
+			list_del_init(&fw_priv->pending_list);
+			if (rc) {
+				fw_state_aborted(fw_priv);
+				written = rc;
+			} else {
+				fw_state_done(fw_priv);
+			}
+			break;
+		}
+		/* fallthrough */
+	default:
+		dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
+		/* fallthrough */
+	case -1:
+		fw_load_abort(fw_sysfs);
+		break;
+	}
+out:
+	mutex_unlock(&fw_lock);
+	return written;
+}
+
+static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
+
+static void firmware_rw_data(struct fw_priv *fw_priv, char *buffer,
+			   loff_t offset, size_t count, bool read)
+{
+	if (read)
+		memcpy(buffer, fw_priv->data + offset, count);
+	else
+		memcpy(fw_priv->data + offset, buffer, count);
+}
+
+static void firmware_rw(struct fw_priv *fw_priv, char *buffer,
+			loff_t offset, size_t count, bool read)
+{
+	while (count) {
+		void *page_data;
+		int page_nr = offset >> PAGE_SHIFT;
+		int page_ofs = offset & (PAGE_SIZE-1);
+		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
+
+		page_data = kmap(fw_priv->pages[page_nr]);
+
+		if (read)
+			memcpy(buffer, page_data + page_ofs, page_cnt);
+		else
+			memcpy(page_data + page_ofs, buffer, page_cnt);
+
+		kunmap(fw_priv->pages[page_nr]);
+		buffer += page_cnt;
+		offset += page_cnt;
+		count -= page_cnt;
+	}
+}
+
+static ssize_t firmware_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 fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t ret_count;
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (!fw_priv || fw_sysfs_done(fw_priv)) {
+		ret_count = -ENODEV;
+		goto out;
+	}
+	if (offset > fw_priv->size) {
+		ret_count = 0;
+		goto out;
+	}
+	if (count > fw_priv->size - offset)
+		count = fw_priv->size - offset;
+
+	ret_count = count;
+
+	if (fw_priv->data)
+		firmware_rw_data(fw_priv, buffer, offset, count, true);
+	else
+		firmware_rw(fw_priv, buffer, offset, count, true);
+
+out:
+	mutex_unlock(&fw_lock);
+	return ret_count;
+}
+
+static int fw_realloc_pages(struct fw_sysfs *fw_sysfs, int min_size)
+{
+	struct fw_priv *fw_priv= fw_sysfs->fw_priv;
+	int pages_needed = PAGE_ALIGN(min_size) >> PAGE_SHIFT;
+
+	/* If the array of pages is too small, grow it... */
+	if (fw_priv->page_array_size < pages_needed) {
+		int new_array_size = max(pages_needed,
+					 fw_priv->page_array_size * 2);
+		struct page **new_pages;
+
+		new_pages = vmalloc(new_array_size * sizeof(void *));
+		if (!new_pages) {
+			fw_load_abort(fw_sysfs);
+			return -ENOMEM;
+		}
+		memcpy(new_pages, fw_priv->pages,
+		       fw_priv->page_array_size * sizeof(void *));
+		memset(&new_pages[fw_priv->page_array_size], 0, sizeof(void *) *
+		       (new_array_size - fw_priv->page_array_size));
+		vfree(fw_priv->pages);
+		fw_priv->pages = new_pages;
+		fw_priv->page_array_size = new_array_size;
+	}
+
+	while (fw_priv->nr_pages < pages_needed) {
+		fw_priv->pages[fw_priv->nr_pages] =
+			alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
+
+		if (!fw_priv->pages[fw_priv->nr_pages]) {
+			fw_load_abort(fw_sysfs);
+			return -ENOMEM;
+		}
+		fw_priv->nr_pages++;
+	}
+	return 0;
+}
+
+/**
+ * firmware_data_write - write method for firmware
+ * @filp: open sysfs file
+ * @kobj: kobject for the device
+ * @bin_attr: bin_attr structure
+ * @buffer: buffer being written
+ * @offset: buffer offset for write in total data store area
+ * @count: buffer size
+ *
+ *	Data written to the 'data' attribute will be later handed to
+ *	the driver as a firmware image.
+ **/
+static ssize_t firmware_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 fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t retval;
+
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (!fw_priv || fw_sysfs_done(fw_priv)) {
+		retval = -ENODEV;
+		goto out;
+	}
+
+	if (fw_priv->data) {
+		if (offset + count > fw_priv->allocated_size) {
+			retval = -ENOMEM;
+			goto out;
+		}
+		firmware_rw_data(fw_priv, buffer, offset, count, false);
+		retval = count;
+	} else {
+		retval = fw_realloc_pages(fw_sysfs, offset + count);
+		if (retval)
+			goto out;
+
+		retval = count;
+		firmware_rw(fw_priv, buffer, offset, count, false);
+	}
+
+	fw_priv->size = max_t(size_t, offset + count, fw_priv->size);
+out:
+	mutex_unlock(&fw_lock);
+	return retval;
+}
+
+static struct bin_attribute firmware_attr_data = {
+	.attr = { .name = "data", .mode = 0644 },
+	.size = 0,
+	.read = firmware_data_read,
+	.write = firmware_data_write,
+};
+
+static struct attribute *fw_dev_attrs[] = {
+	&dev_attr_loading.attr,
+	NULL
+};
+
+static struct bin_attribute *fw_dev_bin_attrs[] = {
+	&firmware_attr_data,
+	NULL
+};
+
+static const struct attribute_group fw_dev_attr_group = {
+	.attrs = fw_dev_attrs,
+	.bin_attrs = fw_dev_bin_attrs,
+};
+
+static const struct attribute_group *fw_dev_attr_groups[] = {
+	&fw_dev_attr_group,
+	NULL
+};
+
+static struct fw_sysfs *
+fw_create_instance(struct firmware *firmware, const char *fw_name,
+		   struct device *device, unsigned int opt_flags)
+{
+	struct fw_sysfs *fw_sysfs;
+	struct device *f_dev;
+
+	fw_sysfs = kzalloc(sizeof(*fw_sysfs), GFP_KERNEL);
+	if (!fw_sysfs) {
+		fw_sysfs = ERR_PTR(-ENOMEM);
+		goto exit;
+	}
+
+	fw_sysfs->nowait = !!(opt_flags & FW_OPT_NOWAIT);
+	fw_sysfs->fw = firmware;
+	f_dev = &fw_sysfs->dev;
+
+	device_initialize(f_dev);
+	dev_set_name(f_dev, "%s", fw_name);
+	f_dev->parent = device;
+	f_dev->class = &firmware_class;
+	f_dev->groups = fw_dev_attr_groups;
+exit:
+	return fw_sysfs;
+}
+
+/* load a firmware via user helper */
+static int _request_firmware_load(struct fw_sysfs *fw_sysfs,
+				  unsigned int opt_flags, long timeout)
+{
+	int retval = 0;
+	struct device *f_dev = &fw_sysfs->dev;
+	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
+
+	/* fall back on userspace loading */
+	if (!fw_priv->data)
+		fw_priv->is_paged_buf = true;
+
+	dev_set_uevent_suppress(f_dev, true);
+
+	retval = device_add(f_dev);
+	if (retval) {
+		dev_err(f_dev, "%s: device_register failed\n", __func__);
+		goto err_put_dev;
+	}
+
+	mutex_lock(&fw_lock);
+	list_add(&fw_priv->pending_list, &pending_fw_head);
+	mutex_unlock(&fw_lock);
+
+	if (opt_flags & FW_OPT_UEVENT) {
+		fw_priv->need_uevent = true;
+		dev_set_uevent_suppress(f_dev, false);
+		dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_name);
+		kobject_uevent(&fw_sysfs->dev.kobj, KOBJ_ADD);
+	} else {
+		timeout = MAX_JIFFY_OFFSET;
+	}
+
+	retval = fw_sysfs_wait_timeout(fw_priv, timeout);
+	if (retval < 0) {
+		mutex_lock(&fw_lock);
+		fw_load_abort(fw_sysfs);
+		mutex_unlock(&fw_lock);
+	}
+
+	if (fw_state_is_aborted(fw_priv)) {
+		if (retval == -ERESTARTSYS)
+			retval = -EINTR;
+		else
+			retval = -EAGAIN;
+	} else if (fw_priv->is_paged_buf && !fw_priv->data)
+		retval = -ENOMEM;
+
+	device_del(f_dev);
+err_put_dev:
+	put_device(f_dev);
+	return retval;
+}
+
+static int fw_load_from_user_helper(struct firmware *firmware,
+				    const char *name, struct device *device,
+				    unsigned int opt_flags)
+{
+	struct fw_sysfs *fw_sysfs;
+	long timeout;
+	int ret;
+
+	timeout = firmware_loading_timeout();
+	if (opt_flags & FW_OPT_NOWAIT) {
+		timeout = usermodehelper_read_lock_wait(timeout);
+		if (!timeout) {
+			dev_dbg(device, "firmware: %s loading timed out\n",
+				name);
+			return -EBUSY;
+		}
+	} else {
+		ret = usermodehelper_read_trylock();
+		if (WARN_ON(ret)) {
+			dev_err(device, "firmware: %s will not be loaded\n",
+				name);
+			return ret;
+		}
+	}
+
+	fw_sysfs = fw_create_instance(firmware, name, device, opt_flags);
+	if (IS_ERR(fw_sysfs)) {
+		ret = PTR_ERR(fw_sysfs);
+		goto out_unlock;
+	}
+
+	fw_sysfs->fw_priv = firmware->priv;
+	ret = _request_firmware_load(fw_sysfs, opt_flags, timeout);
+
+	if (!ret)
+		ret = assign_fw(firmware, device, opt_flags);
+
+out_unlock:
+	usermodehelper_read_unlock();
+
+	return ret;
+}
+
+static bool fw_force_sysfs_fallback(unsigned int opt_flags)
+{
+	if (fw_fallback_config.force_sysfs_fallback)
+		return true;
+	if (!(opt_flags & FW_OPT_USERHELPER))
+		return false;
+	return true;
+}
+
+static bool fw_run_sysfs_fallback(unsigned int opt_flags)
+{
+	if ((opt_flags & FW_OPT_NOFALLBACK))
+		return false;
+
+	return fw_force_sysfs_fallback(opt_flags);
+}
+
+int fw_sysfs_fallback(struct firmware *fw, const char *name,
+		      struct device *device,
+		      unsigned int opt_flags,
+		      int ret)
+{
+	if (!fw_run_sysfs_fallback(opt_flags))
+		return ret;
+
+	dev_warn(device, "Falling back to user helper\n");
+	return fw_load_from_user_helper(fw, name, device, opt_flags);
+}