The filename can be overridden but it expects a non-blocking source of entropy.
A typical invocation would be:
qemu -object rng-random,id=rng0 -device virtio-rng-pci,rng=rng0
This can also be used with /dev/urandom by using the command line:
qemu -object rng-random,filename=/dev/urandom,id=rng0 \
-device virtio-rng-pci,rng=rng0
Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
---
v1 -> v2
- merged header split patch into this one
---
backends/Makefile.objs | 2 +-
backends/rng-random.c | 161 ++++++++++++++++++++++++++++++++++++++++++++++
include/qemu/rng-random.h | 22 +++++++
3 files changed, 184 insertions(+), 1 deletion(-)
create mode 100644 backends/rng-random.c
create mode 100644 include/qemu/rng-random.h
diff --git a/backends/Makefile.objs b/backends/Makefile.objs
index 06e08c7..23ca19b 100644
--- a/backends/Makefile.objs
+++ b/backends/Makefile.objs
@@ -1 +1 @@
-common-obj-y += rng.o
+common-obj-y += rng.o rng-random.o
diff --git a/backends/rng-random.c b/backends/rng-random.c
new file mode 100644
index 0000000..8325686
--- /dev/null
+++ b/backends/rng-random.c
@@ -0,0 +1,161 @@
+/*
+ * QEMU Random Number Generator Backend
+ *
+ * Copyright IBM, Corp. 2012
+ *
+ * Authors:
+ * Anthony Liguori <aligu...@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-random.h"
+#include "qemu/rng.h"
+#include "qerror.h"
+#include "main-loop.h"
+
+struct RndRandom
+{
+ RngBackend parent;
+
+ int fd;
+ char *filename;
+
+ EntropyReceiveFunc *receive_func;
+ void *opaque;
+ size_t size;
+};
+
+/**
+ * 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)
+{
+ RndRandom *s = RNG_RANDOM(opaque);
+ uint8_t buffer[s->size];
+ ssize_t len;
+
+ len = read(s->fd, buffer, s->size);
+ g_assert(len != -1);
+
+ s->receive_func(s->opaque, buffer, s->size);
+ s->receive_func = NULL;
+
+ qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+}
+
+static void rng_random_request_entropy(RngBackend *b, size_t size,
+ EntropyReceiveFunc *receive_entropy,
+ void *opaque)
+{
+ RndRandom *s = RNG_RANDOM(b);
+
+ if (s->receive_func) {
+ s->receive_func(s->opaque, NULL, 0);
+ }
+
+ s->receive_func = receive_entropy;
+ s->opaque = opaque;
+ s->size = size;
+
+ qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
+}
+
+static void rng_random_opened(RngBackend *b, Error **errp)
+{
+ RndRandom *s = RNG_RANDOM(b);
+
+ if (s->filename == NULL) {
+ error_set(errp, QERR_INVALID_PARAMETER_VALUE,
+ "filename", "a valid filename");
+ } else {
+ s->fd = open(s->filename, O_RDONLY | O_NONBLOCK);
+
+ if (s->fd == -1) {
+ error_set(errp, QERR_OPEN_FILE_FAILED, s->filename);
+ }
+ }
+}
+
+static char *rng_random_get_filename(Object *obj, Error **errp)
+{
+ RndRandom *s = RNG_RANDOM(obj);
+
+ if (s->filename) {
+ return g_strdup(s->filename);
+ }
+
+ return NULL;
+}
+
+static void rng_random_set_filename(Object *obj, const char *filename,
+ Error **errp)
+{
+ RngBackend *b = RNG_BACKEND(obj);
+ RndRandom *s = RNG_RANDOM(obj);
+
+ if (b->opened) {
+ error_set(errp, QERR_PERMISSION_DENIED);
+ return;
+ }
+
+ if (s->filename) {
+ g_free(s->filename);
+ }
+
+ s->filename = g_strdup(filename);
+}
+
+static void rng_random_init(Object *obj)
+{
+ RndRandom *s = RNG_RANDOM(obj);
+
+ object_property_add_str(obj, "filename",
+ rng_random_get_filename,
+ rng_random_set_filename,
+ NULL);
+
+ s->filename = g_strdup("/dev/random");
+}
+
+static void rng_random_finalize(Object *obj)
+{
+ RndRandom *s = RNG_RANDOM(obj);
+
+ qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+
+ if (s->fd != -1) {
+ 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;
+}
+
+static TypeInfo rng_random_info = {
+ .name = TYPE_RNG_RANDOM,
+ .parent = TYPE_RNG_BACKEND,
+ .instance_size = sizeof(RndRandom),
+ .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);
diff --git a/include/qemu/rng-random.h b/include/qemu/rng-random.h
new file mode 100644
index 0000000..6249290
--- /dev/null
+++ b/include/qemu/rng-random.h
@@ -0,0 +1,22 @@
+/*
+ * QEMU Random Number Generator Backend
+ *
+ * Copyright IBM, Corp. 2012
+ *
+ * Authors:
+ * Anthony Liguori <aligu...@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.
+ */
+#ifndef QEMU_RNG_RANDOM_H
+#define QEMU_RNG_RANDOM_H
+
+#include "qemu/object.h"
+
+#define TYPE_RNG_RANDOM "rng-random"
+#define RNG_RANDOM(obj) OBJECT_CHECK(RndRandom, (obj), TYPE_RNG_RANDOM)
+
+typedef struct RndRandom RndRandom;
+
+#endif
--
1.8.0
