cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

rng-random.c (3739B)

      1/*
      2 * QEMU Random Number Generator Backend
      3 *
      4 * Copyright IBM, Corp. 2012
      5 *
      6 * Authors:
      7 *  Anthony Liguori   <aliguori@us.ibm.com>
      8 *
      9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
     10 * See the COPYING file in the top-level directory.
     11 */
     12
     13#include "qemu/osdep.h"
     14#include "sysemu/rng-random.h"
     15#include "sysemu/rng.h"
     16#include "qapi/error.h"
     17#include "qapi/qmp/qerror.h"
     18#include "qemu/main-loop.h"
     19#include "qemu/module.h"
     20
     21struct RngRandom
     22{
     23    RngBackend parent;
     24
     25    int fd;
     26    char *filename;
     27};
     28
     29/**
     30 * A simple and incomplete backend to request entropy from /dev/random.
     31 *
     32 * This backend exposes an additional "filename" property that can be used to
     33 * set the filename to use to open the backend.
     34 */
     35
     36static void entropy_available(void *opaque)
     37{
     38    RngRandom *s = RNG_RANDOM(opaque);
     39
     40    while (!QSIMPLEQ_EMPTY(&s->parent.requests)) {
     41        RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
     42        ssize_t len;
     43
     44        len = read(s->fd, req->data, req->size);
     45        if (len < 0 && errno == EAGAIN) {
     46            return;
     47        }
     48        g_assert(len != -1);
     49
     50        req->receive_entropy(req->opaque, req->data, len);
     51
     52        rng_backend_finalize_request(&s->parent, req);
     53    }
     54
     55    /* We've drained all requests, the fd handler can be reset. */
     56    qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
     57}
     58
     59static void rng_random_request_entropy(RngBackend *b, RngRequest *req)
     60{
     61    RngRandom *s = RNG_RANDOM(b);
     62
     63    if (QSIMPLEQ_EMPTY(&s->parent.requests)) {
     64        /* If there are no pending requests yet, we need to
     65         * install our fd handler. */
     66        qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
     67    }
     68}
     69
     70static void rng_random_opened(RngBackend *b, Error **errp)
     71{
     72    RngRandom *s = RNG_RANDOM(b);
     73
     74    if (s->filename == NULL) {
     75        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
     76                   "filename", "a valid filename");
     77    } else {
     78        s->fd = qemu_open_old(s->filename, O_RDONLY | O_NONBLOCK);
     79        if (s->fd == -1) {
     80            error_setg_file_open(errp, errno, s->filename);
     81        }
     82    }
     83}
     84
     85static char *rng_random_get_filename(Object *obj, Error **errp)
     86{
     87    RngRandom *s = RNG_RANDOM(obj);
     88
     89    return g_strdup(s->filename);
     90}
     91
     92static void rng_random_set_filename(Object *obj, const char *filename,
     93                                 Error **errp)
     94{
     95    RngBackend *b = RNG_BACKEND(obj);
     96    RngRandom *s = RNG_RANDOM(obj);
     97
     98    if (b->opened) {
     99        error_setg(errp, QERR_PERMISSION_DENIED);
    100        return;
    101    }
    102
    103    g_free(s->filename);
    104    s->filename = g_strdup(filename);
    105}
    106
    107static void rng_random_init(Object *obj)
    108{
    109    RngRandom *s = RNG_RANDOM(obj);
    110
    111    s->filename = g_strdup("/dev/urandom");
    112    s->fd = -1;
    113}
    114
    115static void rng_random_finalize(Object *obj)
    116{
    117    RngRandom *s = RNG_RANDOM(obj);
    118
    119    if (s->fd != -1) {
    120        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
    121        qemu_close(s->fd);
    122    }
    123
    124    g_free(s->filename);
    125}
    126
    127static void rng_random_class_init(ObjectClass *klass, void *data)
    128{
    129    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
    130
    131    rbc->request_entropy = rng_random_request_entropy;
    132    rbc->opened = rng_random_opened;
    133    object_class_property_add_str(klass, "filename",
    134                                  rng_random_get_filename,
    135                                  rng_random_set_filename);
    136
    137}
    138
    139static const TypeInfo rng_random_info = {
    140    .name = TYPE_RNG_RANDOM,
    141    .parent = TYPE_RNG_BACKEND,
    142    .instance_size = sizeof(RngRandom),
    143    .class_init = rng_random_class_init,
    144    .instance_init = rng_random_init,
    145    .instance_finalize = rng_random_finalize,
    146};
    147
    148static void register_types(void)
    149{
    150    type_register_static(&rng_random_info);
    151}
    152
    153type_init(register_types);