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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 | ||
19 | #define TYPE_RNG_EGD "rng-egd" | |
20 | #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD) | |
21 | ||
22 | typedef struct RngEgd | |
23 | { | |
24 | RngBackend parent; | |
25 | ||
26 | CharBackend chr; | |
27 | char *chr_name; | |
28 | } RngEgd; | |
29 | ||
30 | static void rng_egd_request_entropy(RngBackend *b, RngRequest *req) | |
31 | { | |
32 | RngEgd *s = RNG_EGD(b); | |
33 | size_t size = req->size; | |
34 | ||
35 | while (size > 0) { | |
36 | uint8_t header[2]; | |
37 | uint8_t len = MIN(size, 255); | |
38 | ||
39 | /* synchronous entropy request */ | |
40 | header[0] = 0x02; | |
41 | header[1] = len; | |
42 | ||
43 | /* XXX this blocks entire thread. Rewrite to use | |
44 | * qemu_chr_fe_write and background I/O callbacks */ | |
45 | qemu_chr_fe_write_all(&s->chr, header, sizeof(header)); | |
46 | ||
47 | size -= len; | |
48 | } | |
49 | } | |
50 | ||
51 | static int rng_egd_chr_can_read(void *opaque) | |
52 | { | |
53 | RngEgd *s = RNG_EGD(opaque); | |
54 | RngRequest *req; | |
55 | int size = 0; | |
56 | ||
57 | QSIMPLEQ_FOREACH(req, &s->parent.requests, next) { | |
58 | size += req->size - req->offset; | |
59 | } | |
60 | ||
61 | return size; | |
62 | } | |
63 | ||
64 | static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size) | |
65 | { | |
66 | RngEgd *s = RNG_EGD(opaque); | |
67 | size_t buf_offset = 0; | |
68 | ||
69 | while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) { | |
70 | RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests); | |
71 | int len = MIN(size, req->size - req->offset); | |
72 | ||
73 | memcpy(req->data + req->offset, buf + buf_offset, len); | |
74 | buf_offset += len; | |
75 | req->offset += len; | |
76 | size -= len; | |
77 | ||
78 | if (req->offset == req->size) { | |
79 | req->receive_entropy(req->opaque, req->data, req->size); | |
80 | ||
81 | rng_backend_finalize_request(&s->parent, req); | |
82 | } | |
83 | } | |
84 | } | |
85 | ||
86 | static void rng_egd_opened(RngBackend *b, Error **errp) | |
87 | { | |
88 | RngEgd *s = RNG_EGD(b); | |
89 | Chardev *chr; | |
90 | ||
91 | if (s->chr_name == NULL) { | |
92 | error_setg(errp, QERR_INVALID_PARAMETER_VALUE, | |
93 | "chardev", "a valid character device"); | |
94 | return; | |
95 | } | |
96 | ||
97 | chr = qemu_chr_find(s->chr_name); | |
98 | if (chr == NULL) { | |
99 | error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, | |
100 | "Device '%s' not found", s->chr_name); | |
101 | return; | |
102 | } | |
103 | if (!qemu_chr_fe_init(&s->chr, chr, errp)) { | |
104 | return; | |
105 | } | |
106 | ||
107 | /* FIXME we should resubmit pending requests when the CDS reconnects. */ | |
108 | qemu_chr_fe_set_handlers(&s->chr, rng_egd_chr_can_read, | |
109 | rng_egd_chr_read, NULL, s, NULL, true); | |
110 | } | |
111 | ||
112 | static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp) | |
113 | { | |
114 | RngBackend *b = RNG_BACKEND(obj); | |
115 | RngEgd *s = RNG_EGD(b); | |
116 | ||
117 | if (b->opened) { | |
118 | error_setg(errp, QERR_PERMISSION_DENIED); | |
119 | } else { | |
120 | g_free(s->chr_name); | |
121 | s->chr_name = g_strdup(value); | |
122 | } | |
123 | } | |
124 | ||
125 | static char *rng_egd_get_chardev(Object *obj, Error **errp) | |
126 | { | |
127 | RngEgd *s = RNG_EGD(obj); | |
128 | Chardev *chr = qemu_chr_fe_get_driver(&s->chr); | |
129 | ||
130 | if (chr && chr->label) { | |
131 | return g_strdup(chr->label); | |
132 | } | |
133 | ||
134 | return NULL; | |
135 | } | |
136 | ||
137 | static void rng_egd_init(Object *obj) | |
138 | { | |
139 | object_property_add_str(obj, "chardev", | |
140 | rng_egd_get_chardev, rng_egd_set_chardev, | |
141 | NULL); | |
142 | } | |
143 | ||
144 | static void rng_egd_finalize(Object *obj) | |
145 | { | |
146 | RngEgd *s = RNG_EGD(obj); | |
147 | ||
148 | qemu_chr_fe_deinit(&s->chr, false); | |
149 | g_free(s->chr_name); | |
150 | } | |
151 | ||
152 | static void rng_egd_class_init(ObjectClass *klass, void *data) | |
153 | { | |
154 | RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); | |
155 | ||
156 | rbc->request_entropy = rng_egd_request_entropy; | |
157 | rbc->opened = rng_egd_opened; | |
158 | } | |
159 | ||
160 | static const TypeInfo rng_egd_info = { | |
161 | .name = TYPE_RNG_EGD, | |
162 | .parent = TYPE_RNG_BACKEND, | |
163 | .instance_size = sizeof(RngEgd), | |
164 | .class_init = rng_egd_class_init, | |
165 | .instance_init = rng_egd_init, | |
166 | .instance_finalize = rng_egd_finalize, | |
167 | }; | |
168 | ||
169 | static void register_types(void) | |
170 | { | |
171 | type_register_static(&rng_egd_info); | |
172 | } | |
173 | ||
174 | type_init(register_types); |