[PATCH v2 01/18] test_firmware: Test platform fw loading on non-EFI systems

Kees Cook
2020-07-22T19:30:34Z

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 header file so it 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>
---
drivers/firmware/efi/embedded-firmware.c | 21 ++++++++++++++++-----
drivers/firmware/efi/embedded-firmware.h | 19 +++++++++++++++++++
include/linux/efi_embedded_fw.h | 13 -------------
lib/test_firmware.c | 5 +++++
4 files changed, 40 insertions(+), 18 deletions(-)
create mode 100644 drivers/firmware/efi/embedded-firmware.h

diff --git a/drivers/firmware/efi/embedded-firmware.c b/drivers/firmware/efi/embedded-firmware.c
index a1b199de9006..0fb03cd0a5a2 100644
--- a/drivers/firmware/efi/embedded-firmware.c
+++ b/drivers/firmware/efi/embedded-firmware.c
@@ -14,11 +14,22 @@
#include <linux/vmalloc.h>
#include <crypto/sha.h>

+#include "embedded-firmware.h"
+
+#ifdef CONFIG_TEST_FIRMWARE
+# define EFI_EMBEDDED_FW_VISIBILITY
+#else
+# define EFI_EMBEDDED_FW_VISIBILITY static
+#endif
+
+EFI_EMBEDDED_FW_VISIBILITY LIST_HEAD(efi_embedded_fw_list);
+EFI_EMBEDDED_FW_VISIBILITY bool efi_embedded_fw_checked;
+
/* Exported for use by lib/test_firmware.c only */
-LIST_HEAD(efi_embedded_fw_list);
+#ifdef CONFIG_TEST_FIRMWARE
EXPORT_SYMBOL_GPL(efi_embedded_fw_list);
-
-static bool checked_for_fw;
+EXPORT_SYMBOL_GPL(efi_embedded_fw_checked);
+#endif

static const struct dmi_system_id * const embedded_fw_table[] = {
#ifdef CONFIG_TOUCHSCREEN_DMI
@@ -119,14 +130,14 @@ 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/drivers/firmware/efi/embedded-firmware.h b/drivers/firmware/efi/embedded-firmware.h
new file mode 100644
index 000000000000..34113316d068
--- /dev/null
+++ b/drivers/firmware/efi/embedded-firmware.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EFI_EMBEDDED_FW_INTERNAL_H_
+#define _EFI_EMBEDDED_FW_INTERNAL_H_
+
+/*
+ * This struct and efi_embedded_fw_list are private to the efi-embedded fw
+ * implementation they only in separate header for use by lib/test_firmware.c.
+ */
+struct efi_embedded_fw {
+ struct list_head list;
+ const char *name;
+ const u8 *data;
+ size_t length;
+};
+
+extern struct list_head efi_embedded_fw_list;
+extern bool efi_embedded_fw_checked;
+
+#endif /* _EFI_EMBEDDED_FW_INTERNAL_H_ */
diff --git a/include/linux/efi_embedded_fw.h b/include/linux/efi_embedded_fw.h
index 57eac5241303..4ad5db9f5312 100644
--- a/include/linux/efi_embedded_fw.h
+++ b/include/linux/efi_embedded_fw.h
@@ -7,19 +7,6 @@

#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!
- */
-struct efi_embedded_fw {
- struct list_head list;
- const char *name;
- const u8 *data;
- 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..62af792e151c 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -489,6 +489,7 @@ static ssize_t trigger_request_store(struct device *dev,
static DEVICE_ATTR_WO(trigger_request);

#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+#include "../drivers/firmware/efi/embedded-firmware.h"
static ssize_t trigger_request_platform_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@@ -501,6 +502,7 @@ 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 +515,8 @@ 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 +534,7 @@ 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);