[PATCH v1 1/2] cmd: nvedit_efi: use efi_auth_var_get_guid() for the default GUID

[Heinrich Schuchardt]

On 7/14/26 11:48, Aristo Chen wrote:
> do_env_set_efi() hand rolls the mapping from well known variable names
> to their default vendor GUID and has already drifted from the canonical
> name_type[] table in efi_var_common.c: it does not know "dbr", so
> "env set -e dbr" operates on the variable under EFI_GLOBAL_VARIABLE_GUID
> instead of the image security database GUID, silently creating a
> variable that nothing will ever consume.
> 
> Convert the variable name to UTF-16 before selecting the GUID and let
> efi_auth_var_get_guid() do the lookup. That function knows all
> authenticated variables including "dbr" and falls back to
> EFI_GLOBAL_VARIABLE_GUID for any other name, so behaviour is unchanged
> for "db", "dbx", "dbt" and non-authenticated variables. Future
> additions to the table now apply to the shell command automatically.
> 
> Since the conversion now happens before the value parsing loop, free
> the UTF-16 name at the common exit label so the error path there does
> not leak it.
> 
> Also drop the unmap_sysmem() call right after efi_set_variable_int():
> the common exit path already unmaps the value for the -i case and frees
> it otherwise, so the value was unmapped twice. On sandbox the second
> call triggers a spurious "Address not mapped" warning for addresses
> that get a tagged mapping.
> 
> Signed-off-by: Aristo Chen <aristo.chen at canonical.com>

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

> ---
>   cmd/nvedit_efi.c | 22 ++++++++--------------
>   1 file changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/cmd/nvedit_efi.c b/cmd/nvedit_efi.c
> index 3a36f94775b..f38802e4f4d 100644
> --- a/cmd/nvedit_efi.c
> +++ b/cmd/nvedit_efi.c
> @@ -448,13 +448,14 @@ int do_env_set_efi(struct cmd_tbl *cmdtp, int flag, int argc,
>   		return CMD_RET_USAGE;
>   
>   	var_name = argv[0];
> -	if (default_guid) {
> -		if (!strcmp(var_name, "db") || !strcmp(var_name, "dbx") ||
> -		    !strcmp(var_name, "dbt"))
> -			guid = efi_guid_image_security_database;
> -		else
> -			guid = efi_global_variable_guid;
> +	var_name16 = efi_convert_string(var_name);
> +	if (!var_name16) {
> +		printf("## Out of memory\n");
> +		ret = CMD_RET_FAILURE;
> +		goto out;
>   	}
> +	if (default_guid)
> +		guid = *efi_auth_var_get_guid(var_name16);
>   
>   	if (verbose) {
>   		printf("GUID: %pUl (%pUs)\n", &guid, &guid);
> @@ -479,16 +480,8 @@ int do_env_set_efi(struct cmd_tbl *cmdtp, int flag, int argc,
>   			       16, 1, value, size, true);
>   	}
>   
> -	var_name16 = efi_convert_string(var_name);
> -	if (!var_name16) {
> -		printf("## Out of memory\n");
> -		ret = CMD_RET_FAILURE;
> -		goto out;
> -	}
>   	ret = efi_set_variable_int(var_name16, &guid, attributes, size, value,
>   				   true);
> -	free(var_name16);
> -	unmap_sysmem(value);
>   	if (ret == EFI_SUCCESS) {
>   		ret = CMD_RET_SUCCESS;
>   	} else {
> @@ -518,6 +511,7 @@ int do_env_set_efi(struct cmd_tbl *cmdtp, int flag, int argc,
>   		ret = CMD_RET_FAILURE;
>   	}
>   out:
> +	free(var_name16);
>   	if (value_on_memory)
>   		unmap_sysmem(value);
>   	else