153 lines
3.6 KiB
C
153 lines
3.6 KiB
C
/*
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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-random.h"
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#include "sysemu/rng.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/main-loop.h"
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#include "qemu/module.h"
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struct RngRandom
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{
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RngBackend parent;
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int fd;
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char *filename;
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};
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/**
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* A simple and incomplete backend to request entropy from /dev/random.
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*
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* This backend exposes an additional "filename" property that can be used to
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* set the filename to use to open the backend.
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*/
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static void entropy_available(void *opaque)
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{
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RngRandom *s = RNG_RANDOM(opaque);
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while (!QSIMPLEQ_EMPTY(&s->parent.requests)) {
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RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
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ssize_t len;
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len = read(s->fd, req->data, req->size);
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if (len < 0 && errno == EAGAIN) {
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return;
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}
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g_assert(len != -1);
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req->receive_entropy(req->opaque, req->data, len);
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rng_backend_finalize_request(&s->parent, req);
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}
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/* We've drained all requests, the fd handler can be reset. */
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qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
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}
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static void rng_random_request_entropy(RngBackend *b, RngRequest *req)
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{
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RngRandom *s = RNG_RANDOM(b);
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if (QSIMPLEQ_EMPTY(&s->parent.requests)) {
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/* If there are no pending requests yet, we need to
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* install our fd handler. */
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qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
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}
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}
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static void rng_random_opened(RngBackend *b, Error **errp)
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{
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RngRandom *s = RNG_RANDOM(b);
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if (s->filename == NULL) {
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error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
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"filename", "a valid filename");
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} else {
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s->fd = qemu_open(s->filename, O_RDONLY | O_NONBLOCK);
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if (s->fd == -1) {
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error_setg_file_open(errp, errno, s->filename);
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}
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}
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}
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static char *rng_random_get_filename(Object *obj, Error **errp)
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{
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RngRandom *s = RNG_RANDOM(obj);
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return g_strdup(s->filename);
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}
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static void rng_random_set_filename(Object *obj, const char *filename,
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Error **errp)
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{
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RngBackend *b = RNG_BACKEND(obj);
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RngRandom *s = RNG_RANDOM(obj);
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if (b->opened) {
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error_setg(errp, QERR_PERMISSION_DENIED);
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return;
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}
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g_free(s->filename);
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s->filename = g_strdup(filename);
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}
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static void rng_random_init(Object *obj)
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{
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RngRandom *s = RNG_RANDOM(obj);
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object_property_add_str(obj, "filename",
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rng_random_get_filename,
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rng_random_set_filename);
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s->filename = g_strdup("/dev/urandom");
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s->fd = -1;
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}
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static void rng_random_finalize(Object *obj)
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{
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RngRandom *s = RNG_RANDOM(obj);
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if (s->fd != -1) {
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qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
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qemu_close(s->fd);
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}
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g_free(s->filename);
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}
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static void rng_random_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_random_request_entropy;
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rbc->opened = rng_random_opened;
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}
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static const TypeInfo rng_random_info = {
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.name = TYPE_RNG_RANDOM,
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.parent = TYPE_RNG_BACKEND,
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.instance_size = sizeof(RngRandom),
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.class_init = rng_random_class_init,
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.instance_init = rng_random_init,
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.instance_finalize = rng_random_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_random_info);
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}
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type_init(register_types);
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