aboutsummaryrefslogtreecommitdiff
path: root/backends/rng-egd.c
blob: 9e5a5366f7f69399f76dbf612905b0c98b963d30 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
/*
 * 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 "sysemu/rng.h"
#include "sysemu/char.h"
#include "qapi/qmp/qerror.h"
#include "hw/qdev.h" /* just for DEFINE_PROP_CHR */

#define TYPE_RNG_EGD "rng-egd"
#define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD)

typedef struct RngEgd
{
    RngBackend parent;

    CharDriverState *chr;
    char *chr_name;

    GSList *requests;
} RngEgd;

typedef struct RngRequest
{
    EntropyReceiveFunc *receive_entropy;
    uint8_t *data;
    void *opaque;
    size_t offset;
    size_t size;
} RngRequest;

static void rng_egd_request_entropy(RngBackend *b, size_t size,
                                    EntropyReceiveFunc *receive_entropy,
                                    void *opaque)
{
    RngEgd *s = RNG_EGD(b);
    RngRequest *req;

    req = g_malloc(sizeof(*req));

    req->offset = 0;
    req->size = size;
    req->receive_entropy = receive_entropy;
    req->opaque = opaque;
    req->data = g_malloc(req->size);

    while (size > 0) {
        uint8_t header[2];
        uint8_t len = MIN(size, 255);

        /* synchronous entropy request */
        header[0] = 0x02;
        header[1] = len;

        qemu_chr_fe_write(s->chr, header, sizeof(header));

        size -= len;
    }

    s->requests = g_slist_append(s->requests, req);
}

static void rng_egd_free_request(RngRequest *req)
{
    g_free(req->data);
    g_free(req);
}

static int rng_egd_chr_can_read(void *opaque)
{
    RngEgd *s = RNG_EGD(opaque);
    GSList *i;
    int size = 0;

    for (i = s->requests; i; i = i->next) {
        RngRequest *req = i->data;
        size += req->size - req->offset;
    }

    return size;
}

static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
{
    RngEgd *s = RNG_EGD(opaque);

    while (size > 0 && s->requests) {
        RngRequest *req = s->requests->data;
        int len = MIN(size, req->size - req->offset);

        memcpy(req->data + req->offset, buf, len);
        req->offset += len;
        size -= len;

        if (req->offset == req->size) {
            s->requests = g_slist_remove_link(s->requests, s->requests);

            req->receive_entropy(req->opaque, req->data, req->size);

            rng_egd_free_request(req);
        }
    }
}

static void rng_egd_free_requests(RngEgd *s)
{
    GSList *i;

    for (i = s->requests; i; i = i->next) {
        rng_egd_free_request(i->data);
    }

    g_slist_free(s->requests);
    s->requests = NULL;
}

static void rng_egd_cancel_requests(RngBackend *b)
{
    RngEgd *s = RNG_EGD(b);

    /* We simply delete the list of pending requests.  If there is data in the 
     * queue waiting to be read, this is okay, because there will always be
     * more data than we requested originally
     */
    rng_egd_free_requests(s);
}

static void rng_egd_opened(RngBackend *b, Error **errp)
{
    RngEgd *s = RNG_EGD(b);

    if (s->chr_name == NULL) {
        error_set(errp, QERR_INVALID_PARAMETER_VALUE,
                  "chardev", "a valid character device");
        return;
    }

    s->chr = qemu_chr_find(s->chr_name);
    if (s->chr == NULL) {
        error_set(errp, QERR_DEVICE_NOT_FOUND, s->chr_name);
        return;
    }

    if (qemu_chr_fe_claim(s->chr) != 0) {
        error_set(errp, QERR_DEVICE_IN_USE, s->chr_name);
        return;
    }

    /* FIXME we should resubmit pending requests when the CDS reconnects. */
    qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read,
                          NULL, s);
}

static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
{
    RngBackend *b = RNG_BACKEND(obj);
    RngEgd *s = RNG_EGD(b);

    if (b->opened) {
        error_set(errp, QERR_PERMISSION_DENIED);
    } else {
        g_free(s->chr_name);
        s->chr_name = g_strdup(value);
    }
}

static char *rng_egd_get_chardev(Object *obj, Error **errp)
{
    RngEgd *s = RNG_EGD(obj);

    if (s->chr && s->chr->label) {
        return g_strdup(s->chr->label);
    }

    return NULL;
}

static void rng_egd_init(Object *obj)
{
    object_property_add_str(obj, "chardev",
                            rng_egd_get_chardev, rng_egd_set_chardev,
                            NULL);
}

static void rng_egd_finalize(Object *obj)
{
    RngEgd *s = RNG_EGD(obj);

    if (s->chr) {
        qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
        qemu_chr_fe_release(s->chr);
    }

    g_free(s->chr_name);

    rng_egd_free_requests(s);
}

static void rng_egd_class_init(ObjectClass *klass, void *data)
{
    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);

    rbc->request_entropy = rng_egd_request_entropy;
    rbc->cancel_requests = rng_egd_cancel_requests;
    rbc->opened = rng_egd_opened;
}

static const TypeInfo rng_egd_info = {
    .name = TYPE_RNG_EGD,
    .parent = TYPE_RNG_BACKEND,
    .instance_size = sizeof(RngEgd),
    .class_init = rng_egd_class_init,
    .instance_init = rng_egd_init,
    .instance_finalize = rng_egd_finalize,
};

static void register_types(void)
{
    type_register_static(&rng_egd_info);
}

type_init(register_types);