170 lines
4 KiB
C
170 lines
4 KiB
C
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/*
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* QEMU Random Number Generator Backend
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*
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* Copyright IBM, Corp. 2012
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "sysemu/rng.h"
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#include "chardev/char-fe.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/module.h"
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#include "qom/object.h"
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#define TYPE_RNG_EGD "rng-egd"
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OBJECT_DECLARE_SIMPLE_TYPE(RngEgd, RNG_EGD)
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struct RngEgd {
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RngBackend parent;
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CharBackend chr;
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char *chr_name;
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};
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static void rng_egd_request_entropy(RngBackend *b, RngRequest *req)
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{
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RngEgd *s = RNG_EGD(b);
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size_t size = req->size;
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while (size > 0) {
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uint8_t header[2];
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uint8_t len = MIN(size, 255);
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/* synchronous entropy request */
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header[0] = 0x02;
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header[1] = len;
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/* XXX this blocks entire thread. Rewrite to use
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* qemu_chr_fe_write and background I/O callbacks */
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qemu_chr_fe_write_all(&s->chr, header, sizeof(header));
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size -= len;
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}
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}
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static int rng_egd_chr_can_read(void *opaque)
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{
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RngEgd *s = RNG_EGD(opaque);
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RngRequest *req;
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int size = 0;
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QSIMPLEQ_FOREACH(req, &s->parent.requests, next) {
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size += req->size - req->offset;
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}
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return size;
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}
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static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
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{
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RngEgd *s = RNG_EGD(opaque);
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size_t buf_offset = 0;
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while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) {
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RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
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int len = MIN(size, req->size - req->offset);
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memcpy(req->data + req->offset, buf + buf_offset, len);
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buf_offset += len;
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req->offset += len;
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size -= len;
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if (req->offset == req->size) {
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req->receive_entropy(req->opaque, req->data, req->size);
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rng_backend_finalize_request(&s->parent, req);
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}
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}
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}
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static void rng_egd_opened(RngBackend *b, Error **errp)
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{
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RngEgd *s = RNG_EGD(b);
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Chardev *chr;
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if (s->chr_name == NULL) {
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error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
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"chardev", "a valid character device");
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return;
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}
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chr = qemu_chr_find(s->chr_name);
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if (chr == NULL) {
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error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
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"Device '%s' not found", s->chr_name);
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return;
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}
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if (!qemu_chr_fe_init(&s->chr, chr, errp)) {
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return;
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}
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/* FIXME we should resubmit pending requests when the CDS reconnects. */
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qemu_chr_fe_set_handlers(&s->chr, rng_egd_chr_can_read,
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rng_egd_chr_read, NULL, NULL, s, NULL, true);
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}
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static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
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{
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RngBackend *b = RNG_BACKEND(obj);
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RngEgd *s = RNG_EGD(b);
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if (b->opened) {
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error_setg(errp, QERR_PERMISSION_DENIED);
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} else {
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g_free(s->chr_name);
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s->chr_name = g_strdup(value);
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}
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}
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static char *rng_egd_get_chardev(Object *obj, Error **errp)
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{
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RngEgd *s = RNG_EGD(obj);
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Chardev *chr = qemu_chr_fe_get_driver(&s->chr);
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if (chr && chr->label) {
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return g_strdup(chr->label);
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}
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return NULL;
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}
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static void rng_egd_finalize(Object *obj)
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{
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RngEgd *s = RNG_EGD(obj);
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qemu_chr_fe_deinit(&s->chr, false);
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g_free(s->chr_name);
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}
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static void rng_egd_class_init(ObjectClass *klass, void *data)
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{
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RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
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rbc->request_entropy = rng_egd_request_entropy;
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rbc->opened = rng_egd_opened;
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object_class_property_add_str(klass, "chardev",
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rng_egd_get_chardev, rng_egd_set_chardev);
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}
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static const TypeInfo rng_egd_info = {
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.name = TYPE_RNG_EGD,
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.parent = TYPE_RNG_BACKEND,
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.instance_size = sizeof(RngEgd),
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.class_init = rng_egd_class_init,
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.instance_finalize = rng_egd_finalize,
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};
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static void register_types(void)
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{
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type_register_static(&rng_egd_info);
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}
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type_init(register_types);
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