From patchwork Fri Oct 26 14:43:38 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anthony Liguori X-Patchwork-Id: 194498 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 506B02C008A for ; Sat, 27 Oct 2012 01:45:33 +1100 (EST) Received: from localhost ([::1]:52258 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TRlAB-0002nS-Gj for incoming@patchwork.ozlabs.org; Fri, 26 Oct 2012 10:45:31 -0400 Received: from eggs.gnu.org ([208.118.235.92]:56910) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TRl9S-0001Kf-Lz for qemu-devel@nongnu.org; Fri, 26 Oct 2012 10:44:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TRl9R-0007Nc-Ak for qemu-devel@nongnu.org; Fri, 26 Oct 2012 10:44:46 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:42664) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TRl9Q-0007MH-LL for qemu-devel@nongnu.org; Fri, 26 Oct 2012 10:44:45 -0400 Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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X-Received-From: 122.248.162.9 Cc: Amit Shah , Paolo Bonzini , Anthony Liguori , Andreas Faerber , "H. Peter Anvin" Subject: [Qemu-devel] [PATCH 4/6] rng-random: add an RNG backend that uses /dev/random X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The filename can be overridden but it expects a non-blocking source of entropy. A typical invocation would be: qemu -object rng-random,id=rng0 -device virtio-rng-pci,rng=rng0 This can also be used with /dev/urandom by using the command line: qemu -object rng-random,filename=/dev/urandom,id=rng0 \ -device virtio-rng-pci,rng=rng0 Signed-off-by: Anthony Liguori --- backends/Makefile.objs | 2 +- backends/rng-random.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 164 insertions(+), 1 deletion(-) create mode 100644 backends/rng-random.c diff --git a/backends/Makefile.objs b/backends/Makefile.objs index 06e08c7..23ca19b 100644 --- a/backends/Makefile.objs +++ b/backends/Makefile.objs @@ -1 +1 @@ -common-obj-y += rng.o +common-obj-y += rng.o rng-random.o diff --git a/backends/rng-random.c b/backends/rng-random.c new file mode 100644 index 0000000..6b6e4b4 --- /dev/null +++ b/backends/rng-random.c @@ -0,0 +1,163 @@ +/* + * QEMU Random Number Generator Backend + * + * Copyright IBM, Corp. 2012 + * + * Authors: + * Anthony Liguori + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "qemu/rng.h" +#include "qerror.h" +#include "main-loop.h" + +#define TYPE_RNG_RANDOM "rng-random" +#define RNG_RANDOM(obj) OBJECT_CHECK(RndRandom, (obj), TYPE_RNG_RANDOM) + +typedef struct RndRandom +{ + RngBackend parent; + + int fd; + char *filename; + + EntropyReceiveFunc *receive_func; + void *opaque; + size_t size; +} RndRandom; + +/** + * A simple and incomplete backend to request entropy from /dev/random. + * + * This backend exposes an additional "filename" property that can be used to + * set the filename to use to open the backend. + */ + +static void entropy_available(void *opaque) +{ + RndRandom *s = RNG_RANDOM(opaque); + uint8_t buffer[s->size]; + ssize_t len; + + len = read(s->fd, buffer, s->size); + g_assert(len != -1); + + s->receive_func(s->opaque, buffer, s->size); + s->receive_func = NULL; + + qemu_set_fd_handler(s->fd, NULL, NULL, NULL); +} + +static void rng_random_request_entropy(RngBackend *b, size_t size, + EntropyReceiveFunc *receive_entropy, + void *opaque) +{ + RndRandom *s = RNG_RANDOM(b); + + if (s->receive_func) { + s->receive_func(s->opaque, NULL, 0); + } + + s->receive_func = receive_entropy; + s->opaque = opaque; + s->size = size; + + qemu_set_fd_handler(s->fd, entropy_available, NULL, s); +} + +static void rng_random_opened(RngBackend *b, Error **errp) +{ + RndRandom *s = RNG_RANDOM(b); + + if (s->filename == NULL) { + error_set(errp, QERR_INVALID_PARAMETER_VALUE, + "filename", "a valid filename"); + } else { + s->fd = open(s->filename, O_RDONLY | O_NONBLOCK); + + if (s->fd == -1) { + error_set(errp, QERR_OPEN_FILE_FAILED, s->filename); + } + } +} + +static char *rng_random_get_filename(Object *obj, Error **errp) +{ + RndRandom *s = RNG_RANDOM(obj); + + if (s->filename) { + return g_strdup(s->filename); + } + + return NULL; +} + +static void rng_random_set_filename(Object *obj, const char *filename, + Error **errp) +{ + RngBackend *b = RNG_BACKEND(obj); + RndRandom *s = RNG_RANDOM(obj); + + if (b->opened) { + error_set(errp, QERR_PERMISSION_DENIED); + return; + } + + if (s->filename) { + g_free(s->filename); + } + + s->filename = g_strdup(filename); +} + +static void rng_random_init(Object *obj) +{ + RndRandom *s = RNG_RANDOM(obj); + + object_property_add_str(obj, "filename", + rng_random_get_filename, + rng_random_set_filename, + NULL); + + s->filename = g_strdup("/dev/random"); +} + +static void rng_random_finalize(Object *obj) +{ + RndRandom *s = RNG_RANDOM(obj); + + qemu_set_fd_handler(s->fd, NULL, NULL, NULL); + + if (s->fd != -1) { + close(s->fd); + } + + g_free(s->filename); +} + +static void rng_random_class_init(ObjectClass *klass, void *data) +{ + RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); + + rbc->request_entropy = rng_random_request_entropy; + rbc->opened = rng_random_opened; +} + +static TypeInfo rng_random_info = { + .name = TYPE_RNG_RANDOM, + .parent = TYPE_RNG_BACKEND, + .instance_size = sizeof(RndRandom), + .class_init = rng_random_class_init, + .instance_init = rng_random_init, + .instance_finalize = rng_random_finalize, +}; + +static void register_types(void) +{ + type_register_static(&rng_random_info); +} + +type_init(register_types);