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-egd.c (4131B)

      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#include "qom/object.h"
     20
     21#define TYPE_RNG_EGD "rng-egd"
     22OBJECT_DECLARE_SIMPLE_TYPE(RngEgd, RNG_EGD)
     23
     24struct RngEgd {
     25    RngBackend parent;
     26
     27    CharBackend chr;
     28    char *chr_name;
     29};
     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_finalize(Object *obj)
    139{
    140    RngEgd *s = RNG_EGD(obj);
    141
    142    qemu_chr_fe_deinit(&s->chr, false);
    143    g_free(s->chr_name);
    144}
    145
    146static void rng_egd_class_init(ObjectClass *klass, void *data)
    147{
    148    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
    149
    150    rbc->request_entropy = rng_egd_request_entropy;
    151    rbc->opened = rng_egd_opened;
    152    object_class_property_add_str(klass, "chardev",
    153                                  rng_egd_get_chardev, rng_egd_set_chardev);
    154}
    155
    156static const TypeInfo rng_egd_info = {
    157    .name = TYPE_RNG_EGD,
    158    .parent = TYPE_RNG_BACKEND,
    159    .instance_size = sizeof(RngEgd),
    160    .class_init = rng_egd_class_init,
    161    .instance_finalize = rng_egd_finalize,
    162};
    163
    164static void register_types(void)
    165{
    166    type_register_static(&rng_egd_info);
    167}
    168
    169type_init(register_types);