linux/drivers/base/firmware_loader/fallback.c

657 lines
16 KiB
C

// 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 "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);
}
/**
* 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_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)
{
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, enum fw_opt 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
* @opt_flags: flags of options, FW_OPT_*
* @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,
enum fw_opt 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,
enum fw_opt 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, 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(enum fw_opt 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(enum fw_opt 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);
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
* @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,
enum fw_opt 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);
}