/* * 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 "sysemu/rng.h" #include "sysemu/char.h" #include "qapi/qmp/qerror.h" #include "hw/qdev.h" /* just for DEFINE_PROP_CHR */ #define TYPE_RNG_EGD "rng-egd" #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD) typedef struct RngEgd { RngBackend parent; CharDriverState *chr; char *chr_name; GSList *requests; } RngEgd; typedef struct RngRequest { EntropyReceiveFunc *receive_entropy; uint8_t *data; void *opaque; size_t offset; size_t size; } RngRequest; static void rng_egd_request_entropy(RngBackend *b, size_t size, EntropyReceiveFunc *receive_entropy, void *opaque) { RngEgd *s = RNG_EGD(b); RngRequest *req; req = g_malloc(sizeof(*req)); req->offset = 0; req->size = size; req->receive_entropy = receive_entropy; req->opaque = opaque; req->data = g_malloc(req->size); while (size > 0) { uint8_t header[2]; uint8_t len = MIN(size, 255); /* synchronous entropy request */ header[0] = 0x02; header[1] = len; qemu_chr_fe_write(s->chr, header, sizeof(header)); size -= len; } s->requests = g_slist_append(s->requests, req); } static void rng_egd_free_request(RngRequest *req) { g_free(req->data); g_free(req); } static int rng_egd_chr_can_read(void *opaque) { RngEgd *s = RNG_EGD(opaque); GSList *i; int size = 0; for (i = s->requests; i; i = i->next) { RngRequest *req = i->data; 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 && s->requests) { RngRequest *req = s->requests->data; 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) { s->requests = g_slist_remove_link(s->requests, s->requests); req->receive_entropy(req->opaque, req->data, req->size); rng_egd_free_request(req); } } } static void rng_egd_free_requests(RngEgd *s) { GSList *i; for (i = s->requests; i; i = i->next) { rng_egd_free_request(i->data); } g_slist_free(s->requests); s->requests = NULL; } static void rng_egd_cancel_requests(RngBackend *b) { RngEgd *s = RNG_EGD(b); /* We simply delete the list of pending requests. If there is data in the * queue waiting to be read, this is okay, because there will always be * more data than we requested originally */ rng_egd_free_requests(s); } static void rng_egd_opened(RngBackend *b, Error **errp) { RngEgd *s = RNG_EGD(b); if (s->chr_name == NULL) { error_set(errp, QERR_INVALID_PARAMETER_VALUE, "chardev", "a valid character device"); return; } s->chr = qemu_chr_find(s->chr_name); if (s->chr == NULL) { error_set(errp, QERR_DEVICE_NOT_FOUND, s->chr_name); return; } if (qemu_chr_fe_claim(s->chr) != 0) { error_set(errp, QERR_DEVICE_IN_USE, s->chr_name); return; } /* FIXME we should resubmit pending requests when the CDS reconnects. */ qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read, NULL, s); } 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_set(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); if (s->chr && s->chr->label) { return g_strdup(s->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, NULL); } static void rng_egd_finalize(Object *obj) { RngEgd *s = RNG_EGD(obj); if (s->chr) { qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL); qemu_chr_fe_release(s->chr); } g_free(s->chr_name); rng_egd_free_requests(s); } static void rng_egd_class_init(ObjectClass *klass, void *data) { RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); rbc->request_entropy = rng_egd_request_entropy; rbc->cancel_requests = rng_egd_cancel_requests; 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);