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Anthony Liguori5c745212012-06-25 10:34:09 -05001/*
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
Peter Maydell9c058332016-01-29 17:49:54 +000013#include "qemu/osdep.h"
Paolo Bonzinidccfcd02013-04-08 16:55:25 +020014#include "sysemu/rng-random.h"
15#include "sysemu/rng.h"
Paolo Bonzini7b1b5d12012-12-17 18:19:43 +010016#include "qapi/qmp/qerror.h"
Paolo Bonzini1de7afc2012-12-17 18:20:00 +010017#include "qemu/main-loop.h"
Anthony Liguori5c745212012-06-25 10:34:09 -050018
19struct RndRandom
20{
21 RngBackend parent;
22
23 int fd;
24 char *filename;
25
26 EntropyReceiveFunc *receive_func;
27 void *opaque;
28 size_t size;
29};
30
31/**
32 * A simple and incomplete backend to request entropy from /dev/random.
33 *
34 * This backend exposes an additional "filename" property that can be used to
35 * set the filename to use to open the backend.
36 */
37
38static void entropy_available(void *opaque)
39{
40 RndRandom *s = RNG_RANDOM(opaque);
41 uint8_t buffer[s->size];
42 ssize_t len;
43
44 len = read(s->fd, buffer, s->size);
Amit Shahacbbc032013-04-16 15:58:16 +053045 if (len < 0 && errno == EAGAIN) {
46 return;
47 }
Anthony Liguori5c745212012-06-25 10:34:09 -050048 g_assert(len != -1);
49
50 s->receive_func(s->opaque, buffer, len);
51 s->receive_func = NULL;
52
53 qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
54}
55
56static void rng_random_request_entropy(RngBackend *b, size_t size,
57 EntropyReceiveFunc *receive_entropy,
58 void *opaque)
59{
60 RndRandom *s = RNG_RANDOM(b);
61
62 if (s->receive_func) {
63 s->receive_func(s->opaque, NULL, 0);
64 }
65
66 s->receive_func = receive_entropy;
67 s->opaque = opaque;
68 s->size = size;
69
70 qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
71}
72
73static void rng_random_opened(RngBackend *b, Error **errp)
74{
75 RndRandom *s = RNG_RANDOM(b);
76
77 if (s->filename == NULL) {
Markus Armbrusterc6bd8c72015-03-17 11:54:50 +010078 error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
79 "filename", "a valid filename");
Anthony Liguori5c745212012-06-25 10:34:09 -050080 } else {
Stefan Berger7f9c9d12013-03-01 07:53:55 -050081 s->fd = qemu_open(s->filename, O_RDONLY | O_NONBLOCK);
Anthony Liguori5c745212012-06-25 10:34:09 -050082 if (s->fd == -1) {
Luiz Capitulinobc5741a2013-06-07 14:28:02 -040083 error_setg_file_open(errp, errno, s->filename);
Anthony Liguori5c745212012-06-25 10:34:09 -050084 }
85 }
86}
87
88static char *rng_random_get_filename(Object *obj, Error **errp)
89{
90 RndRandom *s = RNG_RANDOM(obj);
91
Markus Armbruster24588102014-12-04 10:26:55 +010092 return g_strdup(s->filename);
Anthony Liguori5c745212012-06-25 10:34:09 -050093}
94
95static void rng_random_set_filename(Object *obj, const char *filename,
96 Error **errp)
97{
98 RngBackend *b = RNG_BACKEND(obj);
99 RndRandom *s = RNG_RANDOM(obj);
100
101 if (b->opened) {
Markus Armbrusterc6bd8c72015-03-17 11:54:50 +0100102 error_setg(errp, QERR_PERMISSION_DENIED);
Anthony Liguori5c745212012-06-25 10:34:09 -0500103 return;
104 }
105
Eduardo Habkostfeced892014-05-30 17:02:18 -0300106 g_free(s->filename);
Anthony Liguori5c745212012-06-25 10:34:09 -0500107 s->filename = g_strdup(filename);
108}
109
110static void rng_random_init(Object *obj)
111{
112 RndRandom *s = RNG_RANDOM(obj);
113
114 object_property_add_str(obj, "filename",
115 rng_random_get_filename,
116 rng_random_set_filename,
117 NULL);
118
119 s->filename = g_strdup("/dev/random");
Paolo Bonzini513b8c72013-12-20 23:21:06 +0100120 s->fd = -1;
Anthony Liguori5c745212012-06-25 10:34:09 -0500121}
122
123static void rng_random_finalize(Object *obj)
124{
125 RndRandom *s = RNG_RANDOM(obj);
126
Anthony Liguori5c745212012-06-25 10:34:09 -0500127 if (s->fd != -1) {
Paolo Bonzini513b8c72013-12-20 23:21:06 +0100128 qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
Stefan Berger7f9c9d12013-03-01 07:53:55 -0500129 qemu_close(s->fd);
Anthony Liguori5c745212012-06-25 10:34:09 -0500130 }
131
132 g_free(s->filename);
133}
134
135static void rng_random_class_init(ObjectClass *klass, void *data)
136{
137 RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
138
139 rbc->request_entropy = rng_random_request_entropy;
140 rbc->opened = rng_random_opened;
141}
142
Andreas Färber8c43a6f2013-01-10 16:19:07 +0100143static const TypeInfo rng_random_info = {
Anthony Liguori5c745212012-06-25 10:34:09 -0500144 .name = TYPE_RNG_RANDOM,
145 .parent = TYPE_RNG_BACKEND,
146 .instance_size = sizeof(RndRandom),
147 .class_init = rng_random_class_init,
148 .instance_init = rng_random_init,
149 .instance_finalize = rng_random_finalize,
150};
151
152static void register_types(void)
153{
154 type_register_static(&rng_random_info);
155}
156
157type_init(register_types);