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

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Commit 8a254d90a7 ("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: bbc6d2c6ef ("efi: vars: Switch to new wrapper layer")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Aditya Garg <gargaditya08@live.com>
This commit is contained in:
Ard Biesheuvel 2022-10-27 15:52:31 +02:00
parent 7d866e38c7
commit f11a74b45d
1 changed files with 20 additions and 48 deletions

68
drivers/firmware/efi/vars.c
View File

@ -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)
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, false);
}
static
efi_status_t check_var_size_nonblocking(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, 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;
}