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SubjectRe: [PATCH v2 2/2] firmware_class: perform new LSM checks
At Mon, 21 Jul 2014 12:06:41 -0700,
Kees Cook wrote:
>
> This attaches LSM hooks to the existing firmware loading interfaces:
> filesystem-found firmware and demand-loaded blobs.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> drivers/base/firmware_class.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index d276e33880be..7399bab71ced 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -28,6 +28,7 @@
> #include <linux/suspend.h>
> #include <linux/syscore_ops.h>
> #include <linux/reboot.h>
> +#include <linux/security.h>
>
> #include <generated/utsrelease.h>
>
> @@ -308,12 +309,17 @@ static int fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf)
> if (rc != size) {
> if (rc > 0)
> rc = -EIO;
> - vfree(buf);
> - return rc;
> + goto fail;
> }
> + rc = security_kernel_fw_from_file(file, buf, size);
> + if (rc)
> + goto fail;
> fw_buf->data = buf;
> fw_buf->size = size;
> return 0;
> +fail:
> + vfree(buf);
> + return rc;
> }
>
> static int fw_get_filesystem_firmware(struct device *device,
> @@ -640,6 +646,12 @@ static ssize_t firmware_loading_store(struct device *dev,
> break;
> case 0:
> if (test_bit(FW_STATUS_LOADING, &fw_buf->status)) {
> + if (security_kernel_fw_from_file(NULL, fw_buf->data,
> + fw_buf->size)) {
> + fw_load_abort(fw_priv);
> + break;
> + }
> set_bit(FW_STATUS_DONE, &fw_buf->status);
> clear_bit(FW_STATUS_LOADING, &fw_buf->status);

security_kernel_fw_from_file() should be called after
fw_map_pages_buf() call (that is found after these lines).
Otherwise fw_buf->buf won't contain a valid buffer pointer.


Takashi


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