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

Commit 8a254d90a775 ("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: bbc6d2c6ef22 ("efi: vars: Switch to new wrapper layer")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Aditya Garg <gargaditya08@live.com>

diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 433b615..0ba9f18 100644 (file)
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -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;
 }
 
 /**
@@ -196,26 +189,6 @@ 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
  *
  * Must be called with efivars_lock held. If @nonblocking is set, it will use
@@ -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;
 }