/* * 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_old(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); 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; object_class_property_add_str(klass, "filename", rng_random_get_filename, rng_random_set_filename); } 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);