From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D42FC433F5 for ; Tue, 9 Nov 2021 18:53:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43D2161179 for ; Tue, 9 Nov 2021 18:53:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242800AbhKIS4D (ORCPT ); Tue, 9 Nov 2021 13:56:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242667AbhKIS4B (ORCPT ); Tue, 9 Nov 2021 13:56:01 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9EC5C061764 for ; Tue, 9 Nov 2021 10:53:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8iCLiLBN5Xl0oh6P9wFFDC6J3HOu+dEV+gfu75yUkRU=; b=glI9A+YbXxeP7aTXB5FSORb8sj x5fa1qgHtI54Fk/tFGb355mhXOT4wPyD94aUM7HAG6PVqjFf8qFxu/4hWRTjKizux3OFlzkKQqaRH uaBlMxwp4vPom7mnR7lPVz9A7dAQN1FKTKTFrUpO4gR9tf6AOzWWj7MGsDBF/Gpqf9i9PiauRL19F ID8ycUBo09dEZ0ZxXmoiHUO3A9zcJAdMzCwux3MKV8eyGW4xfFHfvfdJQSuNHp6bOowFLyi2e8GmP 6uV1buJR4byykdQM5MVM4q9E5EzJj0uUKBsDttJ2ttm+PQBEOVMd2wMuRudC8gCkE4Z8ZeggOAZyV oFoC1aRQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mkWEz-00F74y-IF; Tue, 09 Nov 2021 18:53:05 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 32A173000DD; Tue, 9 Nov 2021 19:53:05 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 20119212EE599; Tue, 9 Nov 2021 19:53:05 +0100 (CET) Date: Tue, 9 Nov 2021 19:53:05 +0100 From: Peter Zijlstra To: Ard Biesheuvel Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Josh Poimboeuf , Jason Baron , Steven Rostedt , Mark Rutland , Kees Cook Subject: Re: [RFC PATCH 3/7] static_call: use helper to access non-exported key Message-ID: References: <20211109164549.1724710-1-ardb@kernel.org> <20211109164549.1724710-4-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211109164549.1724710-4-ardb@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 09, 2021 at 05:45:45PM +0100, Ard Biesheuvel wrote: > @@ -196,13 +190,21 @@ extern long __static_call_return0(void); > EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name)); \ > EXPORT_SYMBOL_GPL(STATIC_CALL_TRAMP(name)) > > +#define EXPORT_STATIC_CALL_GETKEY_HELPER(name) \ > + struct static_call_key *STATIC_CALL_GETKEY(name)(void) { \ > + BUG_ON(!core_kernel_text( \ > + (unsigned long)__builtin_return_address(0))); \ > + return &STATIC_CALL_KEY(name); \ > + } \ > + EXPORT_SYMBOL_GPL(STATIC_CALL_GETKEY(name)) So if I were a nevarious module, I would look up the above symbol from kallsyms (it is exported and easily obtainable) and then simply read the text to discover the key address and we're in business.