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Subject[PATCH 5.8 161/177] test_firmware: Test platform fw loading on non-EFI systems
Date
From: Kees Cook <keescook@chromium.org>

commit baaabecfc80fad255f866563b53b8c7a3eec176e upstream.

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>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200909225354.3118328-1-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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(-)

--- 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_firmw
}
}

- 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;
--- 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.
--- 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 @@ out:
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_
};
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_
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_
rc = count;

out:
+ efi_embedded_fw_checked = saved_efi_embedded_fw_checked;
release_firmware(firmware);
list_del(&efi_embedded_fw.list);
kfree(name);

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