LXR qemu/backends/rng-egd.c

   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.h"
  15#include "chardev/char-fe.h"
  16#include "qapi/error.h"
  17#include "qapi/qmp/qerror.h"
  18#include "qemu/module.h"
  19
  20#define TYPE_RNG_EGD "rng-egd"
  21#define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD)
  22
  23typedef struct RngEgd
  24{
  25    RngBackend parent;
  26
  27    CharBackend chr;
  28    char *chr_name;
  29} RngEgd;
  30
  31static void rng_egd_request_entropy(RngBackend *b, RngRequest *req)
  32{
  33    RngEgd *s = RNG_EGD(b);
  34    size_t size = req->size;
  35
  36    while (size > 0) {
  37        uint8_t header[2];
  38        uint8_t len = MIN(size, 255);
  39
  40        /* synchronous entropy request */
  41        header[0] = 0x02;
  42        header[1] = len;
  43
  44        /* XXX this blocks entire thread. Rewrite to use
  45         * qemu_chr_fe_write and background I/O callbacks */
  46        qemu_chr_fe_write_all(&s->chr, header, sizeof(header));
  47
  48        size -= len;
  49    }
  50}
  51
  52static int rng_egd_chr_can_read(void *opaque)
  53{
  54    RngEgd *s = RNG_EGD(opaque);
  55    RngRequest *req;
  56    int size = 0;
  57
  58    QSIMPLEQ_FOREACH(req, &s->parent.requests, next) {
  59        size += req->size - req->offset;
  60    }
  61
  62    return size;
  63}
  64
  65static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
  66{
  67    RngEgd *s = RNG_EGD(opaque);
  68    size_t buf_offset = 0;
  69
  70    while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) {
  71        RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
  72        int len = MIN(size, req->size - req->offset);
  73
  74        memcpy(req->data + req->offset, buf + buf_offset, len);
  75        buf_offset += len;
  76        req->offset += len;
  77        size -= len;
  78
  79        if (req->offset == req->size) {
  80            req->receive_entropy(req->opaque, req->data, req->size);
  81
  82            rng_backend_finalize_request(&s->parent, req);
  83        }
  84    }
  85}
  86
  87static void rng_egd_opened(RngBackend *b, Error **errp)
  88{
  89    RngEgd *s = RNG_EGD(b);
  90    Chardev *chr;
  91
  92    if (s->chr_name == NULL) {
  93        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
  94                   "chardev", "a valid character device");
  95        return;
  96    }
  97
  98    chr = qemu_chr_find(s->chr_name);
  99    if (chr == NULL) {
 100        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
 101                  "Device '%s' not found", s->chr_name);
 102        return;
 103    }
 104    if (!qemu_chr_fe_init(&s->chr, chr, errp)) {
 105        return;
 106    }
 107
 108    /* FIXME we should resubmit pending requests when the CDS reconnects. */
 109    qemu_chr_fe_set_handlers(&s->chr, rng_egd_chr_can_read,
 110                             rng_egd_chr_read, NULL, NULL, s, NULL, true);
 111}
 112
 113static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
 114{
 115    RngBackend *b = RNG_BACKEND(obj);
 116    RngEgd *s = RNG_EGD(b);
 117
 118    if (b->opened) {
 119        error_setg(errp, QERR_PERMISSION_DENIED);
 120    } else {
 121        g_free(s->chr_name);
 122        s->chr_name = g_strdup(value);
 123    }
 124}
 125
 126static char *rng_egd_get_chardev(Object *obj, Error **errp)
 127{
 128    RngEgd *s = RNG_EGD(obj);
 129    Chardev *chr = qemu_chr_fe_get_driver(&s->chr);
 130
 131    if (chr && chr->label) {
 132        return g_strdup(chr->label);
 133    }
 134
 135    return NULL;
 136}
 137
 138static void rng_egd_init(Object *obj)
 139{
 140    object_property_add_str(obj, "chardev",
 141                            rng_egd_get_chardev, rng_egd_set_chardev,
 142                            NULL);
 143}
 144
 145static void rng_egd_finalize(Object *obj)
 146{
 147    RngEgd *s = RNG_EGD(obj);
 148
 149    qemu_chr_fe_deinit(&s->chr, false);
 150    g_free(s->chr_name);
 151}
 152
 153static void rng_egd_class_init(ObjectClass *klass, void *data)
 154{
 155    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
 156
 157    rbc->request_entropy = rng_egd_request_entropy;
 158    rbc->opened = rng_egd_opened;
 159}
 160
 161static const TypeInfo rng_egd_info = {
 162    .name = TYPE_RNG_EGD,
 163    .parent = TYPE_RNG_BACKEND,
 164    .instance_size = sizeof(RngEgd),
 165    .class_init = rng_egd_class_init,
 166    .instance_init = rng_egd_init,
 167    .instance_finalize = rng_egd_finalize,
 168};
 169
 170static void register_types(void)
 171{
 172    type_register_static(&rng_egd_info);
 173}
 174
 175type_init(register_types);
 176