qemu/backends/rng-egd.c
Amos Kong 1eb1bd9eaf rng-egd: offset the point when repeatedly read from the buffer
The buffer content might be read out more than once, currently
we just repeatedly read the first data block, buffer offset is
missing.

Cc: qemu-stable@nongnu.org
Signed-off-by: Amos Kong <akong@redhat.com>
Message-id: 1385023371-8198-3-git-send-email-akong@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
2013-11-21 07:55:37 -08:00

232 lines
5.2 KiB
C

/*
* 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 {
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);