Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752303AbbHTU00 (ORCPT ); Thu, 20 Aug 2015 16:26:26 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:33139 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751753AbbHTU0Y (ORCPT ); Thu, 20 Aug 2015 16:26:24 -0400 Date: Thu, 20 Aug 2015 21:26:20 +0100 From: Matt Fleming To: "Lee, Chun-Yi" Cc: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Matthew Garrett , Len Brown , Pavel Machek , Josh Boyer , Vojtech Pavlik , Matt Fleming , Jiri Kosina , "H. Peter Anvin" , Ingo Molnar , "Lee, Chun-Yi" Subject: Re: [PATCH v2 05/16] x86/efi: Get entropy through EFI random number generator protocol Message-ID: <20150820202620.GF2567@codeblueprint.co.uk> References: <1439273796-25359-1-git-send-email-jlee@suse.com> <1439273796-25359-6-git-send-email-jlee@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1439273796-25359-6-git-send-email-jlee@suse.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1400 Lines: 38 On Tue, 11 Aug, at 02:16:25PM, Lee, Chun-Yi wrote: > + > +static unsigned long efi_get_rng64(efi_system_table_t *sys_table, > + void **rng_handle) > +{ > + const struct efi_config *efi_early = __efi_early(); > + efi_rng_protocol_64 *rng = NULL; > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; > + u64 *handles = (u64 *)(unsigned long)rng_handle; > + efi_status_t status; > + unsigned long rng_number; > + > + status = efi_call_early(handle_protocol, handles[0], > + &rng_proto, (void **)&rng); > + if (status != EFI_SUCCESS) > + efi_printk(sys_table, "Failed to get EFI_RNG_PROTOCOL handles\n"); > + > + if (status == EFI_SUCCESS && rng) { > + status = efi_early->call((unsigned long)rng->get_rng, rng, NULL, > + sizeof(rng_number), &rng_number); Actually, one thing just occurred to me - you're not passing an RNGAlgorithm value and are relying upon the firmware's default implementation. I don't think that's a safe bet, the default could be anything and might vary across implementations. Can we do a little better here and pick a "preferred" algorithm instead of the default? -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/