[PATCH v4 4/8] firmware: add call to LSM hook before firmware sysfs fallback

[Luis R. Rodriguez]

On Tue, May 29, 2018 at 02:01:56PM -0400, Mimi Zohar wrote:
> Add an LSM hook prior to allowing firmware sysfs fallback loading.

Acked-by: Luis R. Rodriguez <mcgrof at kernel.org>

> Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
> Cc: Luis R. Rodriguez <mcgrof at suse.com>
> Cc: David Howells <dhowells at redhat.com>
> Cc: Kees Cook <keescook at chromium.org>
> 
> Changelog v4:
> - call new LSM security_kernel_arg hook
> 
> Changelog v2:
> - call security_kernel_read_blob()
> - rename the READING_FIRMWARE_FALLBACK kernel_read_file_id enumeration to
> READING_FIRMWARE_FALLBACK_SYSFS.
> ---
>  drivers/base/firmware_loader/fallback.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
> index 358354148dec..2443bda81631 100644
> --- a/drivers/base/firmware_loader/fallback.c
> +++ b/drivers/base/firmware_loader/fallback.c
> @@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags)
>  
>  static bool fw_run_sysfs_fallback(unsigned int 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;
> @@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags)
>  	if ((opt_flags & FW_OPT_NOFALLBACK))
>  		return false;
>  
> +	/* Also permit LSMs and IMA to fail firmware sysfs fallback */
> +	ret = security_kernel_load_data(LOADING_FIRMWARE);
> +	if (ret < 0)
> +		return ret;
> +
>  	return fw_force_sysfs_fallback(opt_flags);
>  }
>  
> -- 
> 2.7.5
> 
> 

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