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authorAnthony Liguori <aliguori@us.ibm.com>2012-06-25 13:13:31 -0500
committerAnthony Liguori <aliguori@us.ibm.com>2012-11-16 08:36:13 -0600
commit1da2738f5566263177d09c1b9eaf7cbeeb17e815 (patch)
tree43a5e8ef46231913ac66edb90afe584ce5a5aa35 /backends/rng-egd.c
parent5c74521d249486fa3e749dbbf6d56a70d4d7235f (diff)
rng-egd: introduce EGD compliant RNG backend
This backend talks EGD to a CharDriverState. A typical way to invoke this would be: qemu -chardev socket,host=localhost,port=1024,id=chr0 \ -object rng-egd,chardev=chr0,id=egd0 \ -device virtio-rng-pci,rng=egd0 Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'backends/rng-egd.c')
-rw-r--r--backends/rng-egd.c215
1 files changed, 215 insertions, 0 deletions
diff --git a/backends/rng-egd.c b/backends/rng-egd.c
new file mode 100644
index 0000000000..ec5835839a
--- /dev/null
+++ b/backends/rng-egd.c
@@ -0,0 +1,215 @@
+/*
+ * 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/rng.h"
+#include "qemu-char.h"
+#include "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);
+
+ while (size > 0 && s->requests) {
+ RngRequest *req = s->requests->data;
+ int len = MIN(size, req->size - req->offset);
+
+ memcpy(req->data + req->offset, buf, 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_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
+ */
+ g_slist_free_full(s->requests,
+ (GDestroyNotify)rng_egd_free_request);
+ s->requests = NULL;
+}
+
+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;
+ }
+
+ /* 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);
+ }
+
+ g_free(s->chr_name);
+
+ g_slist_free_full(s->requests, (GDestroyNotify)rng_egd_free_request);
+ s->requests = NULL;
+}
+
+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 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);