Commit 0c542edd authored by Jeremy Kerr's avatar Jeremy Kerr Committed by Matt Fleming
Browse files

efi: Handle deletions and size changes in efivarfs_write_file 



A write to an efivarfs file will not always result in a variable of
'count' size after the EFI SetVariable() call. We may have appended to
the existing data (ie, with the EFI_VARIABLE_APPEND_WRITE attribute), or
even have deleted the variable (with an authenticated variable update,
with a zero datasize).

This change re-reads the updated variable from firmware, to check for
size changes and deletions. In the latter case, we need to drop the
dentry.

Signed-off-by: default avatarJeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent 5d9db883

drivers/firmware/efivars.c

+39 −10
Original line number Diff line number Diff line
@@ -658,6 +658,7 @@ static ssize_t efivarfs_file_write(struct file *file, 
	u32 attributes;

	struct inode *inode = file->f_mapping->host;

	int datasize = count - sizeof(attributes);

	unsigned long newdatasize;



	if (count < sizeof(attributes))

		return -EINVAL;
@@ -696,32 +697,60 @@ static ssize_t efivarfs_file_write(struct file *file, 


	switch (status) {

	case EFI_SUCCESS:

		mutex_lock(&inode->i_mutex);

		i_size_write(inode, count);

		mutex_unlock(&inode->i_mutex);

		break;

	case EFI_INVALID_PARAMETER:

		count = -EINVAL;

		break;

		goto out;

	case EFI_OUT_OF_RESOURCES:

		count = -ENOSPC;

		break;

		goto out;

	case EFI_DEVICE_ERROR:

		count = -EIO;

		break;

		goto out;

	case EFI_WRITE_PROTECTED:

		count = -EROFS;

		break;

		goto out;

	case EFI_SECURITY_VIOLATION:

		count = -EACCES;

		break;

		goto out;

	case EFI_NOT_FOUND:

		count = -ENOENT;

		break;

		goto out;

	default:

		count = -EINVAL;

		break;

		goto out;

	}



	/*

	 * Writing to the variable may have caused a change in size (which

	 * could either be an append or an overwrite), or the variable to be

	 * deleted. Perform a GetVariable() so we can tell what actually

	 * happened.

	 */

	newdatasize = 0;

	status = efivars->ops->get_variable(var->var.VariableName,

					    &var->var.VendorGuid,

					    NULL, &newdatasize,

					    NULL);



	if (status == EFI_BUFFER_TOO_SMALL) {

		mutex_lock(&inode->i_mutex);

		i_size_write(inode, newdatasize + sizeof(attributes));

		mutex_unlock(&inode->i_mutex);



	} else if (status == EFI_NOT_FOUND) {

		spin_lock(&efivars->lock);

		list_del(&var->list);

		spin_unlock(&efivars->lock);

		efivar_unregister(var);

		drop_nlink(inode);

		dput(file->f_dentry);



	} else {

		pr_warn("efivarfs: inconsistent EFI variable implementation? "

				"status = %lx\n", status);

	}



out:

	kfree(data);

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