diff options
Diffstat (limited to 'drivers/base/firmware_loader/fallback.c')
| -rw-r--r-- | drivers/base/firmware_loader/fallback.c | 660 |
1 files changed, 660 insertions, 0 deletions
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c new file mode 100644 index 000000000..0fdd18ce2 --- /dev/null +++ b/drivers/base/firmware_loader/fallback.c @@ -0,0 +1,660 @@ +// 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 <linux/sysctl.h> +#include <linux/vmalloc.h> +#include <linux/module.h> + +#include "fallback.h" +#include "firmware.h" + +/* + * firmware fallback mechanism + */ + +MODULE_IMPORT_NS(FIRMWARE_LOADER_PRIVATE); + +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/aborted and disappearance of 'loading' + */ + if (fw_state_is_aborted(fw_priv) || fw_sysfs_done(fw_priv)) + return; + + 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 sysfs_emit(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 sysfs_emit(buf, "%d\n", loading); +} + +/** + * 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); + + 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)) { + fw_free_paged_buf(fw_priv); + 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 = fw_map_paged_buf(fw_priv); + if (rc) + dev_err(dev, "%s: map pages failed\n", + __func__); + else + rc = security_kernel_post_load_data(fw_priv->data, + fw_priv->size, + LOADING_FIRMWARE, "blob"); + + /* + * Same logic as fw_load_abort, only the DONE bit + * is ignored and we set ABORT only on failure. + */ + 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) +{ + int err; + + err = fw_grow_paged_buf(fw_sysfs->fw_priv, + PAGE_ALIGN(min_size) >> PAGE_SHIFT); + if (err) + fw_load_abort(fw_sysfs); + return err; +} + +/** + * 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, u32 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; +} + +/** + * 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_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); +} |