fuzz: use qemu_get_exec_dir
[qemu.git] / backends / rng-random.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-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
21 struct 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
36 static 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
59 static 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
70 static 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
85 static 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
92 static 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
107 static void rng_random_init(Object *obj)
108 {
109 RngRandom *s = RNG_RANDOM(obj);
110
111 object_property_add_str(obj, "filename",
112 rng_random_get_filename,
113 rng_random_set_filename);
114
115 s->filename = g_strdup("/dev/urandom");
116 s->fd = -1;
117 }
118
119 static void rng_random_finalize(Object *obj)
120 {
121 RngRandom *s = RNG_RANDOM(obj);
122
123 if (s->fd != -1) {
124 qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
125 qemu_close(s->fd);
126 }
127
128 g_free(s->filename);
129 }
130
131 static void rng_random_class_init(ObjectClass *klass, void *data)
132 {
133 RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
134
135 rbc->request_entropy = rng_random_request_entropy;
136 rbc->opened = rng_random_opened;
137 }
138
139 static 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
148 static void register_types(void)
149 {
150 type_register_static(&rng_random_info);
151 }
152
153 type_init(register_types);