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

Luis R. Rodriguez
2018-06-01T18:19:16Z

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@kernel.org>

> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> Cc: Luis R. Rodriguez <mcgrof@suse.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: Kees Cook <keescook@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
>
>

--
Do not panic