On Thu, 10 Sep 2020 at 01:54, Kees Cook keescook@chromium.org wrote:

On non-EFI systems, it wasn't possible to test the platform firmware loader because it will have never set "checked_fw" during __init. Instead, allow the test code to override this check. Additionally split the declarations into a private symbol namespace so there is greater enforcement of the symbol visibility.

Fixes: 548193cba2a7 ("test_firmware: add support for firmware_request_platform") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org

---

This is split out from the larger kernel_read_file series: https://lore.kernel.org/lkml/20200729175845.1745471-1-keescook@chromium.org/ specifically this was: https://lore.kernel.org/lkml/20200729175845.1745471-2-keescook@chromium.org/

I've dropped the review tags, since this is changing the "how" of the patch...

drivers/firmware/efi/embedded-firmware.c | 10 +++++----- include/linux/efi_embedded_fw.h | 6 ++---- lib/test_firmware.c | 9 +++++++++ 3 files changed, 16 insertions(+), 9 deletions(-)

Acked-by: Ard Biesheuvel ardb@kernel.org

diff --git a/drivers/firmware/efi/embedded-firmware.c b/drivers/firmware/efi/embedded-firmware.c index a1b199de9006..84e32634ed6c 100644 --- a/drivers/firmware/efi/embedded-firmware.c +++ b/drivers/firmware/efi/embedded-firmware.c @@ -16,9 +16,9 @@

/* Exported for use by lib/test_firmware.c only */ LIST_HEAD(efi_embedded_fw_list); -EXPORT_SYMBOL_GPL(efi_embedded_fw_list);

-static bool checked_for_fw; +EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_list, TEST_FIRMWARE); +bool efi_embedded_fw_checked; +EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_checked, TEST_FIRMWARE);

static const struct dmi_system_id * const embedded_fw_table[] = { #ifdef CONFIG_TOUCHSCREEN_DMI @@ -119,14 +119,14 @@ void __init efi_check_for_embedded_firmwares(void) } }

•   checked_for_fw = true;
  

•   efi_embedded_fw_checked = true;
  

}

int efi_get_embedded_fw(const char *name, const u8 **data, size_t *size) { struct efi_embedded_fw *iter, *fw = NULL;

•   if (!checked_for_fw) {
  

•   if (!efi_embedded_fw_checked) {
            pr_warn("Warning %s called while we did not check for embedded fw\n",
                    __func__);
            return -ENOENT;
  

diff --git a/include/linux/efi_embedded_fw.h b/include/linux/efi_embedded_fw.h index 57eac5241303..a97a12bb2c9e 100644 --- a/include/linux/efi_embedded_fw.h +++ b/include/linux/efi_embedded_fw.h @@ -8,8 +8,8 @@ #define EFI_EMBEDDED_FW_PREFIX_LEN 8

/*

• • This struct and efi_embedded_fw_list are private to the efi-embedded fw
• • implementation they are in this header for use by lib/test_firmware.c only!

• • This struct is private to the efi-embedded fw implementation.
• • They are in this header for use by lib/test_firmware.c only!
  */

struct efi_embedded_fw { struct list_head list; @@ -18,8 +18,6 @@ struct efi_embedded_fw { size_t length; };

-extern struct list_head efi_embedded_fw_list;

/**

• struct efi_embedded_fw_desc - This struct is used by the EFI embedded-fw

•                           code to search for embedded firmwares.
  

diff --git a/lib/test_firmware.c b/lib/test_firmware.c index 9fee2b93a8d1..06c955057756 100644 --- a/lib/test_firmware.c +++ b/lib/test_firmware.c @@ -26,6 +26,8 @@ #include <linux/vmalloc.h> #include <linux/efi_embedded_fw.h>

+MODULE_IMPORT_NS(TEST_FIRMWARE);

#define TEST_FIRMWARE_NAME "test-firmware.bin" #define TEST_FIRMWARE_NUM_REQS 4 #define TEST_FIRMWARE_BUF_SIZE SZ_1K @@ -489,6 +491,9 @@ static ssize_t trigger_request_store(struct device *dev, static DEVICE_ATTR_WO(trigger_request);

#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE +extern struct list_head efi_embedded_fw_list; +extern bool efi_embedded_fw_checked;

static ssize_t trigger_request_platform_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) @@ -501,6 +506,7 @@ static ssize_t trigger_request_platform_store(struct device *dev, }; struct efi_embedded_fw efi_embedded_fw; const struct firmware *firmware = NULL;

•   bool saved_efi_embedded_fw_checked;
    char *name;
    int rc;
  
  

@@ -513,6 +519,8 @@ static ssize_t trigger_request_platform_store(struct device *dev, efi_embedded_fw.data = (void *)test_data; efi_embedded_fw.length = sizeof(test_data); list_add(&efi_embedded_fw.list, &efi_embedded_fw_list);

•   saved_efi_embedded_fw_checked = efi_embedded_fw_checked;
  

•   efi_embedded_fw_checked = true;
  
    pr_info("loading '%s'\n", name);
    rc = firmware_request_platform(&firmware, name, dev);
  

@@ -530,6 +538,7 @@ static ssize_t trigger_request_platform_store(struct device *dev, rc = count;

out:

•   efi_embedded_fw_checked = saved_efi_embedded_fw_checked;
    release_firmware(firmware);
    list_del(&efi_embedded_fw.list);
    kfree(name);
  

-- 2.25.1