1 files changed, 661 insertions, 0 deletions

diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
new file mode 100644
index 000000000000..9b65837256d6
--- /dev/null
+++ b/drivers/base/firmware_loader/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 "fallback.h"
+#include "firmware.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);
+}