| // 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; |
| } |
| 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); |
| } |