diff options
Diffstat (limited to 'backends/rng-egd.c')
| -rw-r--r-- | backends/rng-egd.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/backends/rng-egd.c b/backends/rng-egd.c new file mode 100644 index 00000000..6c134096 --- /dev/null +++ b/backends/rng-egd.c @@ -0,0 +1,233 @@ +/* + * 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_setg(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, ERROR_CLASS_DEVICE_NOT_FOUND, + "Device '%s' not found", s->chr_name); + return; + } + + if (qemu_chr_fe_claim(s->chr) != 0) { + error_setg(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_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); + + 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); |