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 | |
20 | #define TYPE_RNG_EGD "rng-egd" |
21 | #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD) |
22 | |
23 | typedef struct RngEgd |
24 | { |
25 | RngBackend parent; |
26 | |
27 | CharBackend chr; |
28 | char *chr_name; |
29 | } RngEgd; |
30 | |
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 [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 | |
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 | |
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 | |
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 | |
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, QERR_PERMISSION_DENIED); |
120 | } else { |
121 | g_free(s->chr_name); |
122 | s->chr_name = g_strdup(value); |
123 | } |
124 | } |
125 | |
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 | |
138 | static void rng_egd_init(Object *obj) |
139 | { |
140 | object_property_add_str(obj, "chardev" , |
141 | rng_egd_get_chardev, rng_egd_set_chardev, |
142 | NULL); |
143 | } |
144 | |
145 | static void rng_egd_finalize(Object *obj) |
146 | { |
147 | RngEgd *s = RNG_EGD(obj); |
148 | |
149 | qemu_chr_fe_deinit(&s->chr, false); |
150 | g_free(s->chr_name); |
151 | } |
152 | |
153 | static void rng_egd_class_init(ObjectClass *klass, void *data) |
154 | { |
155 | RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); |
156 | |
157 | rbc->request_entropy = rng_egd_request_entropy; |
158 | rbc->opened = rng_egd_opened; |
159 | } |
160 | |
161 | static const TypeInfo rng_egd_info = { |
162 | .name = TYPE_RNG_EGD, |
163 | .parent = TYPE_RNG_BACKEND, |
164 | .instance_size = sizeof(RngEgd), |
165 | .class_init = rng_egd_class_init, |
166 | .instance_init = rng_egd_init, |
167 | .instance_finalize = rng_egd_finalize, |
168 | }; |
169 | |
170 | static void register_types(void) |
171 | { |
172 | type_register_static(&rng_egd_info); |
173 | } |
174 | |
175 | type_init(register_types); |
176 | |