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"
22 OBJECT_DECLARE_SIMPLE_TYPE(RngEgd, RNG_EGD)
23
24 struct RngEgd {
25 RngBackend parent;
26
27 CharBackend chr;
28 char *chr_name;
29 };
30
rng_egd_request_entropy(RngBackend * b,RngRequest * req)31 static 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
rng_egd_chr_can_read(void * opaque)52 static 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
rng_egd_chr_read(void * opaque,const uint8_t * buf,int size)65 static 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
rng_egd_opened(RngBackend * b,Error ** errp)87 static 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
rng_egd_set_chardev(Object * obj,const char * value,Error ** errp)113 static 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, "Property 'chardev' can no longer be set");
120 } else {
121 g_free(s->chr_name);
122 s->chr_name = g_strdup(value);
123 }
124 }
125
rng_egd_get_chardev(Object * obj,Error ** errp)126 static 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
rng_egd_finalize(Object * obj)138 static 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
rng_egd_class_init(ObjectClass * klass,void * data)146 static 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
156 static 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
register_types(void)164 static void register_types(void)
165 {
166 type_register_static(&rng_egd_info);
167 }
168
169 type_init(register_types);
170