Archipelago » qemu

/*

 * 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-random.h"

#include "qemu/rng.h"

#include "qapi/qmp/qerror.h"

#include "qemu/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, len);

    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 = qemu_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) {

        qemu_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 const 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);