On Fri, Feb 23, 2018 at 6:46 PM, Luis R. Rodriguez <mcgrof@xxxxxxxxxx> wrote:
> The timeout is a fallback construct, so we can just stuff the
> timeout configuration under struct firmware_fallback_config.
>
> While at it, add a few helpers which vets the use of getting or
> setting the timeout as an int. The main use of the timeout is
> to set a timeout for completion, and that is used as an unsigned
> long. There a few cases however where it makes sense to get or
> set the timeout as an int, the helpers annotate these use cases
> have been properly vetted for.
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
-Kees
> ---
> drivers/base/firmware_loader.c | 46 ++++++++++++++++++++++++++++++------------
> 1 file changed, 33 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/base/firmware_loader.c b/drivers/base/firmware_loader.c
> index 2d819875348d..9757f9fff01e 100644
> --- a/drivers/base/firmware_loader.c
> +++ b/drivers/base/firmware_loader.c
> @@ -266,21 +266,38 @@ static inline bool fw_state_is_aborted(struct fw_priv *fw_priv)
> *
> * @force_sysfs_fallback: force the sysfs fallback mechanism to be used
> * as if one had enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.
> + * @old_timeout: for internal use
> + * @loading_timeout: the timeout to wait for the fallback mechanism before
> + * giving up, in seconds.
> */
> struct firmware_fallback_config {
> - bool force_sysfs_fallback;
> + const bool force_sysfs_fallback;
> + int old_timeout;
> + int loading_timeout;
> };
>
> -static const struct firmware_fallback_config fw_fallback_config = {
> +static struct firmware_fallback_config fw_fallback_config = {
> .force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
> + .loading_timeout = 60,
> + .old_timeout = 60,
> };
>
> -static int old_timeout;
> -static int loading_timeout = 60; /* In seconds */
> +/* 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;
> +}
>
> static inline long firmware_loading_timeout(void)
> {
> - return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
> + return __firmware_loading_timeout() > 0 ?
> + __firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
> }
>
> /*
> @@ -291,14 +308,14 @@ static inline long firmware_loading_timeout(void)
> */
> static void fw_fallback_set_cache_timeout(void)
> {
> - old_timeout = loading_timeout;
> - loading_timeout = 10;
> + fw_fallback_config.old_timeout = __firmware_loading_timeout();
> + __fw_fallback_set_timeout(10);
> }
>
> /* Restores the timeout to the value last configured during normal operation */
> static void fw_fallback_set_default_timeout(void)
> {
> - loading_timeout = old_timeout;
> + __fw_fallback_set_timeout(fw_fallback_config.old_timeout);
> }
>
> static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
> @@ -677,7 +694,7 @@ static void kill_pending_fw_fallback_reqs(bool only_kill_custom)
> static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
> char *buf)
> {
> - return sprintf(buf, "%d\n", loading_timeout);
> + return sprintf(buf, "%d\n", __firmware_loading_timeout());
> }
>
> /**
> @@ -696,9 +713,12 @@ static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
> static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
> const char *buf, size_t count)
> {
> - loading_timeout = simple_strtol(buf, NULL, 10);
> - if (loading_timeout < 0)
> - loading_timeout = 0;
> + 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;
> }
> @@ -721,7 +741,7 @@ static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env
> {
> if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
> return -ENOMEM;
> - if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
> + if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
> return -ENOMEM;
> if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
> return -ENOMEM;
> --
> 2.16.2
>
--
Kees Cook
Pixel Security
