Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752226AbbG3QLy (ORCPT ); Thu, 30 Jul 2015 12:11:54 -0400 Received: from mga11.intel.com ([192.55.52.93]:9497 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750877AbbG3QLw (ORCPT ); Thu, 30 Jul 2015 12:11:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,577,1432623600"; d="scan'208";a="774596454" Message-ID: <1438272704.11322.13.camel@intel.com> Subject: Re: [RFC PATCH 05/16] x86/efi: Get entropy through EFI random number generator protocol From: Matt Fleming To: "Lee, Chun-Yi" CC: , , , "Rafael J. Wysocki" , "Matthew Garrett" , Len Brown , Pavel Machek , Josh Boyer , "Vojtech Pavlik" , Jiri Kosina , "H. Peter Anvin" , "Lee, Chun-Yi" Date: Thu, 30 Jul 2015 17:11:44 +0100 In-Reply-To: <1437056730-15247-6-git-send-email-jlee@suse.com> References: <1437056730-15247-1-git-send-email-jlee@suse.com> <1437056730-15247-6-git-send-email-jlee@suse.com> Organization: Intel Corporation (UK) Ltd. - Registered No. 1134945 - Pipers Way, Swindon SN3 1RJ Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 (3.12.11-1.fc21) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [163.33.239.181] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3191 Lines: 110 On Thu, 2015-07-16 at 22:25 +0800, Lee, Chun-Yi wrote: > To grab random numbers through EFI protocol as one of the entropies > source of swsusp key, this patch adds the logic for accessing EFI RNG > (random number generator) protocol that's introduced since UEFI 2.4. > > Signed-off-by: Lee, Chun-Yi > --- > arch/x86/boot/compressed/efi_random.c | 193 ++++++++++++++++++++++++++++++++++ > include/linux/efi.h | 46 ++++++++ > 2 files changed, 239 insertions(+) [...] > @@ -2,6 +2,191 @@ > > #include > #include > +#include > + > +static efi_status_t efi_locate_rng(efi_system_table_t *sys_table, > + void ***rng_handle) > +{ > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; > + unsigned long size = 0; > + efi_status_t status; > + > + status = efi_call_early(locate_handle, > + EFI_LOCATE_BY_PROTOCOL, > + &rng_proto, NULL, &size, *rng_handle); > + > + if (status == EFI_BUFFER_TOO_SMALL) { > + status = efi_call_early(allocate_pool, > + EFI_LOADER_DATA, > + size, (void **)rng_handle); > + > + if (status != EFI_SUCCESS) { > + efi_printk(sys_table, " Failed to alloc mem for rng_handle"); > + return status; > + } > + > + status = efi_call_early(locate_handle, > + EFI_LOCATE_BY_PROTOCOL, &rng_proto, > + NULL, &size, *rng_handle); > + } > + > + if (status != EFI_SUCCESS) { > + efi_printk(sys_table, " Failed to locate EFI_RNG_PROTOCOL"); > + goto free_handle; > + } > + > + return EFI_SUCCESS; > + > +free_handle: > + efi_call_early(free_pool, *rng_handle); > + > + return status; > +} I would suggest setting *rng_handle = NULL at the beginning of this function just because if we ever forget to set it that way in the caller this free_pool call might do screwy things. > +static bool efi_rng_supported(efi_system_table_t *sys_table) > +{ > + const struct efi_config *efi_early = __efi_early(); > + u32 random = 0; > + efi_status_t status; > + void **rng_handle = NULL; > + > + status = efi_locate_rng(sys_table, &rng_handle); > + if (status != EFI_SUCCESS) > + return false; > + > + if (efi_early->is64) > + random = efi_rng_supported64(sys_table, rng_handle); > + else > + random = efi_rng_supported32(sys_table, rng_handle); > + > + efi_call_early(free_pool, rng_handle); > + > + return random; Oops, 'random' isn't a bool but it should be. > @@ -51,6 +236,14 @@ static unsigned long get_random_long(unsigned long entropy, > use_i8254 = false; > } > > + if (efi_rng_supported(sys_table)) { > + efi_printk(sys_table, " EFI_RNG"); > + raw = efi_get_rng(sys_table); > + if (raw) > + random ^= raw; > + use_i8254 = false; > + } > + > if (use_i8254) { > efi_printk(sys_table, " i8254"); > random ^= i8254(); Have you looked at the tradeoff in terms of boot time for building a key array in 'unsigned long' chunks as opposed to passing the array and size directly for the RNG protocol? -- 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/