| /* |
| * QEMU Random Number Generator Backend |
| * |
| * Copyright IBM, Corp. 2012 |
| * |
| * Authors: |
| * Anthony Liguori <aliguori@us.ibm.com> |
| * |
| * 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/osdep.h" |
| #include "sysemu/rng-random.h" |
| #include "sysemu/rng.h" |
| #include "qapi/error.h" |
| #include "qapi/qmp/qerror.h" |
| #include "qemu/main-loop.h" |
| #include "qemu/module.h" |
| |
| struct RngRandom |
| { |
| RngBackend parent; |
| |
| int fd; |
| char *filename; |
| }; |
| |
| /** |
| * 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) |
| { |
| RngRandom *s = RNG_RANDOM(opaque); |
| |
| while (!QSIMPLEQ_EMPTY(&s->parent.requests)) { |
| RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests); |
| ssize_t len; |
| |
| len = read(s->fd, req->data, req->size); |
| if (len < 0 && errno == EAGAIN) { |
| return; |
| } |
| g_assert(len != -1); |
| |
| req->receive_entropy(req->opaque, req->data, len); |
| |
| rng_backend_finalize_request(&s->parent, req); |
| } |
| |
| /* We've drained all requests, the fd handler can be reset. */ |
| qemu_set_fd_handler(s->fd, NULL, NULL, NULL); |
| } |
| |
| static void rng_random_request_entropy(RngBackend *b, RngRequest *req) |
| { |
| RngRandom *s = RNG_RANDOM(b); |
| |
| if (QSIMPLEQ_EMPTY(&s->parent.requests)) { |
| /* If there are no pending requests yet, we need to |
| * install our fd handler. */ |
| qemu_set_fd_handler(s->fd, entropy_available, NULL, s); |
| } |
| } |
| |
| static void rng_random_opened(RngBackend *b, Error **errp) |
| { |
| RngRandom *s = RNG_RANDOM(b); |
| |
| if (s->filename == NULL) { |
| error_setg(errp, QERR_INVALID_PARAMETER_VALUE, |
| "filename", "a valid filename"); |
| } else { |
| s->fd = qemu_open(s->filename, O_RDONLY | O_NONBLOCK); |
| if (s->fd == -1) { |
| error_setg_file_open(errp, errno, s->filename); |
| } |
| } |
| } |
| |
| static char *rng_random_get_filename(Object *obj, Error **errp) |
| { |
| RngRandom *s = RNG_RANDOM(obj); |
| |
| return g_strdup(s->filename); |
| } |
| |
| static void rng_random_set_filename(Object *obj, const char *filename, |
| Error **errp) |
| { |
| RngBackend *b = RNG_BACKEND(obj); |
| RngRandom *s = RNG_RANDOM(obj); |
| |
| if (b->opened) { |
| error_setg(errp, QERR_PERMISSION_DENIED); |
| return; |
| } |
| |
| g_free(s->filename); |
| s->filename = g_strdup(filename); |
| } |
| |
| static void rng_random_init(Object *obj) |
| { |
| RngRandom *s = RNG_RANDOM(obj); |
| |
| object_property_add_str(obj, "filename", |
| rng_random_get_filename, |
| rng_random_set_filename); |
| |
| s->filename = g_strdup("/dev/urandom"); |
| s->fd = -1; |
| } |
| |
| static void rng_random_finalize(Object *obj) |
| { |
| RngRandom *s = RNG_RANDOM(obj); |
| |
| if (s->fd != -1) { |
| qemu_set_fd_handler(s->fd, NULL, NULL, NULL); |
| qemu_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 const TypeInfo rng_random_info = { |
| .name = TYPE_RNG_RANDOM, |
| .parent = TYPE_RNG_BACKEND, |
| .instance_size = sizeof(RngRandom), |
| .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); |