236 lines
6.3 KiB
C
236 lines
6.3 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/types.h>
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#include <linux/kconfig.h>
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#include <linux/list.h>
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#include <linux/security.h>
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#include <linux/umh.h>
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#include <linux/sysctl.h>
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#include <linux/module.h>
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#include "fallback.h"
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#include "firmware.h"
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/*
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* firmware fallback mechanism
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*/
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/*
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* use small loading timeout for caching devices' firmware because all these
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* firmware images have been loaded successfully at lease once, also system is
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* ready for completing firmware loading now. The maximum size of firmware in
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* current distributions is about 2M bytes, so 10 secs should be enough.
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*/
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void fw_fallback_set_cache_timeout(void)
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{
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fw_fallback_config.old_timeout = __firmware_loading_timeout();
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__fw_fallback_set_timeout(10);
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}
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/* Restores the timeout to the value last configured during normal operation */
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void fw_fallback_set_default_timeout(void)
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{
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__fw_fallback_set_timeout(fw_fallback_config.old_timeout);
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}
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static long firmware_loading_timeout(void)
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{
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return __firmware_loading_timeout() > 0 ?
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__firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
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}
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static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv, long timeout)
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{
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return __fw_state_wait_common(fw_priv, timeout);
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}
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static LIST_HEAD(pending_fw_head);
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void kill_pending_fw_fallback_reqs(bool only_kill_custom)
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{
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struct fw_priv *fw_priv;
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struct fw_priv *next;
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mutex_lock(&fw_lock);
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list_for_each_entry_safe(fw_priv, next, &pending_fw_head,
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pending_list) {
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if (!fw_priv->need_uevent || !only_kill_custom)
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__fw_load_abort(fw_priv);
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}
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mutex_unlock(&fw_lock);
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}
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/**
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* fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism
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* @fw_sysfs: firmware sysfs information for the firmware to load
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* @timeout: timeout to wait for the load
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*
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* In charge of constructing a sysfs fallback interface for firmware loading.
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**/
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static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout)
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{
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int retval = 0;
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struct device *f_dev = &fw_sysfs->dev;
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struct fw_priv *fw_priv = fw_sysfs->fw_priv;
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/* fall back on userspace loading */
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if (!fw_priv->data)
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fw_priv->is_paged_buf = true;
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dev_set_uevent_suppress(f_dev, true);
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retval = device_add(f_dev);
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if (retval) {
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dev_err(f_dev, "%s: device_register failed\n", __func__);
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goto err_put_dev;
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}
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mutex_lock(&fw_lock);
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if (fw_state_is_aborted(fw_priv)) {
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mutex_unlock(&fw_lock);
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retval = -EINTR;
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goto out;
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}
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list_add(&fw_priv->pending_list, &pending_fw_head);
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mutex_unlock(&fw_lock);
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if (fw_priv->opt_flags & FW_OPT_UEVENT) {
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fw_priv->need_uevent = true;
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dev_set_uevent_suppress(f_dev, false);
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dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_name);
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kobject_uevent(&fw_sysfs->dev.kobj, KOBJ_ADD);
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} else {
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timeout = MAX_JIFFY_OFFSET;
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}
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retval = fw_sysfs_wait_timeout(fw_priv, timeout);
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if (retval < 0 && retval != -ENOENT) {
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mutex_lock(&fw_lock);
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fw_load_abort(fw_sysfs);
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mutex_unlock(&fw_lock);
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}
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if (fw_state_is_aborted(fw_priv)) {
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if (retval == -ERESTARTSYS)
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retval = -EINTR;
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} else if (fw_priv->is_paged_buf && !fw_priv->data)
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retval = -ENOMEM;
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out:
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device_del(f_dev);
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err_put_dev:
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put_device(f_dev);
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return retval;
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}
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static int fw_load_from_user_helper(struct firmware *firmware,
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const char *name, struct device *device,
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u32 opt_flags)
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{
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struct fw_sysfs *fw_sysfs;
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long timeout;
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int ret;
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timeout = firmware_loading_timeout();
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if (opt_flags & FW_OPT_NOWAIT) {
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timeout = usermodehelper_read_lock_wait(timeout);
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if (!timeout) {
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dev_dbg(device, "firmware: %s loading timed out\n",
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name);
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return -EBUSY;
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}
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} else {
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ret = usermodehelper_read_trylock();
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if (WARN_ON(ret)) {
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dev_err(device, "firmware: %s will not be loaded\n",
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name);
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return ret;
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}
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}
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fw_sysfs = fw_create_instance(firmware, name, device, opt_flags);
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if (IS_ERR(fw_sysfs)) {
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ret = PTR_ERR(fw_sysfs);
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goto out_unlock;
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}
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fw_sysfs->fw_priv = firmware->priv;
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ret = fw_load_sysfs_fallback(fw_sysfs, timeout);
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if (!ret)
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ret = assign_fw(firmware, device);
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out_unlock:
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usermodehelper_read_unlock();
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return ret;
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}
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static bool fw_force_sysfs_fallback(u32 opt_flags)
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{
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if (fw_fallback_config.force_sysfs_fallback)
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return true;
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if (!(opt_flags & FW_OPT_USERHELPER))
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return false;
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return true;
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}
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static bool fw_run_sysfs_fallback(u32 opt_flags)
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{
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int ret;
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if (fw_fallback_config.ignore_sysfs_fallback) {
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pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
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return false;
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}
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if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS))
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return false;
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/* Also permit LSMs and IMA to fail firmware sysfs fallback */
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ret = security_kernel_load_data(LOADING_FIRMWARE, true);
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if (ret < 0)
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return false;
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return fw_force_sysfs_fallback(opt_flags);
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}
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/**
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* firmware_fallback_sysfs() - use the fallback mechanism to find firmware
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* @fw: pointer to firmware image
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* @name: name of firmware file to look for
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* @device: device for which firmware is being loaded
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* @opt_flags: options to control firmware loading behaviour, as defined by
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* &enum fw_opt
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* @ret: return value from direct lookup which triggered the fallback mechanism
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*
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* This function is called if direct lookup for the firmware failed, it enables
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* a fallback mechanism through userspace by exposing a sysfs loading
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* interface. Userspace is in charge of loading the firmware through the sysfs
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* loading interface. This sysfs fallback mechanism may be disabled completely
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* on a system by setting the proc sysctl value ignore_sysfs_fallback to true.
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* If this is false we check if the internal API caller set the
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* @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback
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* mechanism. A system may want to enforce the sysfs fallback mechanism at all
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* times, it can do this by setting ignore_sysfs_fallback to false and
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* force_sysfs_fallback to true.
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* Enabling force_sysfs_fallback is functionally equivalent to build a kernel
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* with CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
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**/
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int firmware_fallback_sysfs(struct firmware *fw, const char *name,
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struct device *device,
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u32 opt_flags,
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int ret)
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{
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if (!fw_run_sysfs_fallback(opt_flags))
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return ret;
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if (!(opt_flags & FW_OPT_NO_WARN))
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dev_warn(device, "Falling back to sysfs fallback for: %s\n",
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name);
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else
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dev_dbg(device, "Falling back to sysfs fallback for: %s\n",
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name);
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return fw_load_from_user_helper(fw, name, device, opt_flags);
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}
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