// SPDX-License-Identifier: GPL-2.0 #include <linux/types.h>#include <linux/kconfig.h>#include <linux/list.h>#include <linux/security.h>#include <linux/umh.h>#include <linux/sysctl.h>#include <linux/module.h> #include "fallback.h"#include "firmware.h" /* * firmware fallback mechanism */ /* * 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 int fw_sysfs_wait_timeout(struct fw_priv *fw_priv,  long timeout){	return __fw_state_wait_common(fw_priv, timeout);} static LIST_HEAD(pending_fw_head); void kill_pending_fw_fallback_reqs(bool kill_all){	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 (kill_all || !fw_priv->need_uevent)			 __fw_load_abort(fw_priv);	} 	if (kill_all)		fw_load_abort_all = true; 	mutex_unlock(&fw_lock);} /** * fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism * @fw_sysfs: firmware sysfs information for the firmware to load * @timeout: timeout to wait for the load * * In charge of constructing a sysfs fallback interface for firmware loading. **/static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, 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);	if (fw_load_abort_all || fw_state_is_aborted(fw_priv)) {		mutex_unlock(&fw_lock);		retval = -EINTR;		goto out;	} 	/*	 * device_add() exposes the loading interface before pending_list is	 * linked into pending_fw_head, so fw_state_done() may run first.	 */	if (fw_state_is_done(fw_priv)) {		mutex_unlock(&fw_lock);		goto out;	} 	list_add(&fw_priv->pending_list, &pending_fw_head);	mutex_unlock(&fw_lock); 	if (fw_priv->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 && retval != -ENOENT) {		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 if (fw_priv->is_paged_buf && !fw_priv->data)		retval = -ENOMEM; out:	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,				    u32 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 = fw_load_sysfs_fallback(fw_sysfs, timeout); 	if (!ret)		ret = assign_fw(firmware, device); out_unlock:	usermodehelper_read_unlock(); 	return ret;} static bool fw_force_sysfs_fallback(u32 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(u32 opt_flags){	int ret; 	if (fw_fallback_config.ignore_sysfs_fallback) {		pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");		return false;	} 	if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS))		return false; 	/* Also permit LSMs and IMA to fail firmware sysfs fallback */	ret = security_kernel_load_data(LOADING_FIRMWARE, true);	if (ret < 0)		return false; 	return fw_force_sysfs_fallback(opt_flags);} /** * firmware_fallback_sysfs() - use the fallback mechanism to find firmware * @fw: pointer to firmware image * @name: name of firmware file to look for * @device: device for which firmware is being loaded * @opt_flags: options to control firmware loading behaviour, as defined by *	       &enum fw_opt * @ret: return value from direct lookup which triggered the fallback mechanism * * This function is called if direct lookup for the firmware failed, it enables * a fallback mechanism through userspace by exposing a sysfs loading * interface. Userspace is in charge of loading the firmware through the sysfs * loading interface. This sysfs fallback mechanism may be disabled completely * on a system by setting the proc sysctl value ignore_sysfs_fallback to true. * If this is false we check if the internal API caller set the * @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback * mechanism. A system may want to enforce the sysfs fallback mechanism at all * times, it can do this by setting ignore_sysfs_fallback to false and * force_sysfs_fallback to true. * Enabling force_sysfs_fallback is functionally equivalent to build a kernel * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK. **/int firmware_fallback_sysfs(struct firmware *fw, const char *name,			    struct device *device,			    u32 opt_flags,			    int ret){	if (!fw_run_sysfs_fallback(opt_flags))		return ret; 	if (!(opt_flags & FW_OPT_NO_WARN))		dev_warn(device, "Falling back to sysfs fallback for: %s\n",				 name);	else		dev_dbg(device, "Falling back to sysfs fallback for: %s\n",				name);	return fw_load_from_user_helper(fw, name, device, opt_flags);}