efi_firmware: set EFI capsule dfu_alt_info env explicitly

The current implementation of EFI capsule update uses set_dfu_alt_info() to
set the dfu_alt_info environment variable with the settings it requires.
However, set_dfu_alt_info() is doing this for all DFU operations, even
those unrelated to capsule update.

Thus other uses of DFU, such as DFU boot which sets its own value for the
dfu_alt_info environment variable, will have that setting overwritten with
the capsule update setting. Similarly, any user defined value for the
dfu_alt_info environment variable would get overwritten when any DFU
operation was performed, including simply performing a "dfu 0 list"
command.

The solution is stop using the set_dfu_alt_info() mechanism to set the
dfu_alt_info environment variable and instead explicitly set it to the
capsule update's setting just before performing the capsule update's DFU
operation, and then restore the environment variable back to its original
value.

This patch implements the explicit setting and restoring of the
dfu_alt_info environment variable as part of the EFI capsule update
operation.

The fix is fully implemented in a subsequent patch that removes the capsule
update dfu_alt_info support in set_dfu_alt_info().

Signed-off-by: Jonathan Humphreys <j-humphreys@ti.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
index 5a754c9..0ffaf5c 100644 (file)
--- a/lib/efi_loader/efi_firmware.c
+++ b/lib/efi_loader/efi_firmware.c
@@ -649,8 +649,10 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
        efi_status_t (*progress)(efi_uintn_t completion),
        u16 **abort_reason)
 {
+       int ret;
        efi_status_t status;
        struct fmp_state state = { 0 };
+       char *orig_dfu_env;
 
        EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
                  image_size, vendor_code, progress, abort_reason);
@@ -663,7 +665,28 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
        if (status != EFI_SUCCESS)
                return EFI_EXIT(status);
 
-       if (fit_update(image))
+       orig_dfu_env = env_get("dfu_alt_info");
+       if (orig_dfu_env) {
+               orig_dfu_env = strdup(orig_dfu_env);
+               if (!orig_dfu_env) {
+                       log_err("strdup() failed!\n");
+                       return EFI_EXIT(EFI_OUT_OF_RESOURCES);
+               }
+       }
+       if (env_set("dfu_alt_info", update_info.dfu_string)) {
+               log_err("Unable to set env variable \"dfu_alt_info\"!\n");
+               free(orig_dfu_env);
+               return EFI_EXIT(EFI_DEVICE_ERROR);
+       }
+
+       ret = fit_update(image);
+
+       if (env_set("dfu_alt_info", orig_dfu_env))
+               log_warning("Unable to restore env variable \"dfu_alt_info\".  Further DFU operations may fail!\n");
+
+       free(orig_dfu_env);
+
+       if (ret)
                return EFI_EXIT(EFI_DEVICE_ERROR);
 
        efi_firmware_set_fmp_state_var(&state, image_index);
@@ -717,6 +740,7 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
        u8 dfu_alt_num;
        efi_status_t status;
        struct fmp_state state = { 0 };
+       char *orig_dfu_env;
 
        EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
                  image_size, vendor_code, progress, abort_reason);
@@ -747,8 +771,29 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
                }
        }
 
-       if (dfu_write_by_alt(dfu_alt_num, (void *)image, image_size,
-                            NULL, NULL))
+       orig_dfu_env = env_get("dfu_alt_info");
+       if (orig_dfu_env) {
+               orig_dfu_env = strdup(orig_dfu_env);
+               if (!orig_dfu_env) {
+                       log_err("strdup() failed!\n");
+                       return EFI_EXIT(EFI_OUT_OF_RESOURCES);
+               }
+       }
+       if (env_set("dfu_alt_info", update_info.dfu_string)) {
+               log_err("Unable to set env variable \"dfu_alt_info\"!\n");
+               free(orig_dfu_env);
+               return EFI_EXIT(EFI_DEVICE_ERROR);
+       }
+
+       ret = dfu_write_by_alt(dfu_alt_num, (void *)image, image_size,
+                              NULL, NULL);
+
+       if (env_set("dfu_alt_info", orig_dfu_env))
+               log_warning("Unable to restore env variable \"dfu_alt_info\".  Further DFU operations may fail!\n");
+
+       free(orig_dfu_env);
+
+       if (ret)
                return EFI_EXIT(EFI_DEVICE_ERROR);
 
        efi_firmware_set_fmp_state_var(&state, image_index);