/* * 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.h" #include "chardev/char-fe.h" #include "qapi/error.h" #include "qapi/qmp/qerror.h" #include "qemu/module.h" #define TYPE_RNG_EGD "rng-egd" #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD) typedef struct RngEgd { RngBackend parent; CharBackend chr; char *chr_name; } RngEgd; static void rng_egd_request_entropy(RngBackend *b, RngRequest *req) { RngEgd *s = RNG_EGD(b); size_t size = req->size; while (size > 0) { uint8_t header[2]; uint8_t len = MIN(size, 255); /* synchronous entropy request */ header[0] = 0x02; header[1] = len; /* XXX this blocks entire thread. Rewrite to use * qemu_chr_fe_write and background I/O callbacks */ qemu_chr_fe_write_all(&s->chr, header, sizeof(header)); size -= len; } } static int rng_egd_chr_can_read(void *opaque) { RngEgd *s = RNG_EGD(opaque); RngRequest *req; int size = 0; QSIMPLEQ_FOREACH(req, &s->parent.requests, next) { size += req->size - req->offset; } return size; } static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size) { RngEgd *s = RNG_EGD(opaque); size_t buf_offset = 0; while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) { RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests); int len = MIN(size, req->size - req->offset); memcpy(req->data + req->offset, buf + buf_offset, len); buf_offset += len; req->offset += len; size -= len; if (req->offset == req->size) { req->receive_entropy(req->opaque, req->data, req->size); rng_backend_finalize_request(&s->parent, req); } } } static void rng_egd_opened(RngBackend *b, Error **errp) { RngEgd *s = RNG_EGD(b); Chardev *chr; if (s->chr_name == NULL) { error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "chardev", "a valid character device"); return; } chr = qemu_chr_find(s->chr_name); if (chr == NULL) { error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, "Device '%s' not found", s->chr_name); return; } if (!qemu_chr_fe_init(&s->chr, chr, errp)) { return; } /* FIXME we should resubmit pending requests when the CDS reconnects. */ qemu_chr_fe_set_handlers(&s->chr, rng_egd_chr_can_read, rng_egd_chr_read, NULL, NULL, s, NULL, true); } static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp) { RngBackend *b = RNG_BACKEND(obj); RngEgd *s = RNG_EGD(b); if (b->opened) { error_setg(errp, QERR_PERMISSION_DENIED); } else { g_free(s->chr_name); s->chr_name = g_strdup(value); } } static char *rng_egd_get_chardev(Object *obj, Error **errp) { RngEgd *s = RNG_EGD(obj); Chardev *chr = qemu_chr_fe_get_driver(&s->chr); if (chr && chr->label) { return g_strdup(chr->label); } return NULL; } static void rng_egd_init(Object *obj) { object_property_add_str(obj, "chardev", rng_egd_get_chardev, rng_egd_set_chardev); } static void rng_egd_finalize(Object *obj) { RngEgd *s = RNG_EGD(obj); qemu_chr_fe_deinit(&s->chr, false); g_free(s->chr_name); } static void rng_egd_class_init(ObjectClass *klass, void *data) { RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); rbc->request_entropy = rng_egd_request_entropy; rbc->opened = rng_egd_opened; } static const TypeInfo rng_egd_info = { .name = TYPE_RNG_EGD, .parent = TYPE_RNG_BACKEND, .instance_size = sizeof(RngEgd), .class_init = rng_egd_class_init, .instance_init = rng_egd_init, .instance_finalize = rng_egd_finalize, }; static void register_types(void) { type_register_static(&rng_egd_info); } type_init(register_types);