Commit f11a74b4 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi: efivars: Fix variable writes with unsupported query_variable_store() 



Commit 8a254d90 ("efi: efivars: Fix variable writes without
query_variable_store()") addressed an issue that was introduced during
the EFI variable store refactor, where alternative implementations of
the efivars layer that lacked query_variable_store() would no longer
work.

Unfortunately, there is another case to consider here, which was missed:
if the efivars layer is backed by the EFI runtime services as usual, but
the EFI implementation predates the introduction of QueryVariableInfo(),
we will return EFI_UNSUPPORTED, and this is no longer being dealt with
correctly.

So let's fix this, and while at it, clean up the code a bit, by merging
the check_var_size() routines as well as their callers.

Cc: <stable@vger.kernel.org> # v6.0
Fixes: bbc6d2c6 ("efi: vars: Switch to new wrapper layer")
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Tested-by: default avatarAditya Garg <gargaditya08@live.com>
parent 7d866e38

drivers/firmware/efi/vars.c

+20 −48
Original line number Diff line number Diff line
@@ -21,29 +21,22 @@ static struct efivars *__efivars; 


static DEFINE_SEMAPHORE(efivars_lock);



static efi_status_t check_var_size(u32 attributes, unsigned long size)

{

	const struct efivar_operations *fops;



	fops = __efivars->ops;



	if (!fops->query_variable_store)

		return (size <= SZ_64K) ? EFI_SUCCESS : EFI_OUT_OF_RESOURCES;



	return fops->query_variable_store(attributes, size, false);

}



static

efi_status_t check_var_size_nonblocking(u32 attributes, unsigned long size)

static efi_status_t check_var_size(bool nonblocking, u32 attributes,

				   unsigned long size)

{

	const struct efivar_operations *fops;

	efi_status_t status;



	fops = __efivars->ops;



	if (!fops->query_variable_store)

		status = EFI_UNSUPPORTED;

	else

		status = fops->query_variable_store(attributes, size,

						    nonblocking);

	if (status == EFI_UNSUPPORTED)

		return (size <= SZ_64K) ? EFI_SUCCESS : EFI_OUT_OF_RESOURCES;



	return fops->query_variable_store(attributes, size, true);

	return status;

}



/**
@@ -195,26 +188,6 @@ efi_status_t efivar_get_next_variable(unsigned long *name_size, 
}

EXPORT_SYMBOL_NS_GPL(efivar_get_next_variable, EFIVAR);



/*

 * efivar_set_variable_blocking() - local helper function for set_variable

 *

 * Must be called with efivars_lock held.

 */

static efi_status_t

efivar_set_variable_blocking(efi_char16_t *name, efi_guid_t *vendor,

			     u32 attr, unsigned long data_size, void *data)

{

	efi_status_t status;



	if (data_size > 0) {

		status = check_var_size(attr, data_size +

					      ucs2_strsize(name, 1024));

		if (status != EFI_SUCCESS)

			return status;

	}

	return __efivars->ops->set_variable(name, vendor, attr, data_size, data);

}



/*

 * efivar_set_variable_locked() - set a variable identified by name/vendor

 *
@@ -228,23 +201,21 @@ efi_status_t efivar_set_variable_locked(efi_char16_t *name, efi_guid_t *vendor, 
	efi_set_variable_t *setvar;

	efi_status_t status;



	if (!nonblocking)

		return efivar_set_variable_blocking(name, vendor, attr,

						    data_size, data);

	if (data_size > 0) {

		status = check_var_size(nonblocking, attr,

					data_size + ucs2_strsize(name, 1024));

		if (status != EFI_SUCCESS)

			return status;

	}



	/*

	 * If no _nonblocking variant exists, the ordinary one

	 * is assumed to be non-blocking.

	 */

	setvar = __efivars->ops->set_variable_nonblocking ?:

		 __efivars->ops->set_variable;

	setvar = __efivars->ops->set_variable_nonblocking;

	if (!setvar || !nonblocking)

		 setvar = __efivars->ops->set_variable;



	if (data_size > 0) {

		status = check_var_size_nonblocking(attr, data_size +

							  ucs2_strsize(name, 1024));

		if (status != EFI_SUCCESS)

			return status;

	}

	return setvar(name, vendor, attr, data_size, data);

}

EXPORT_SYMBOL_NS_GPL(efivar_set_variable_locked, EFIVAR);
@@ -264,7 +235,8 @@ efi_status_t efivar_set_variable(efi_char16_t *name, efi_guid_t *vendor, 
	if (efivar_lock())

		return EFI_ABORTED;



	status = efivar_set_variable_blocking(name, vendor, attr, data_size, data);

	status = efivar_set_variable_locked(name, vendor, attr, data_size,

					    data, false);

	efivar_unlock();

	return status;

}