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5c74521d AL |
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/rng-random.h" | |
14 | #include "qemu/rng.h" | |
15 | #include "qerror.h" | |
16 | #include "main-loop.h" | |
17 | ||
18 | struct RndRandom | |
19 | { | |
20 | RngBackend parent; | |
21 | ||
22 | int fd; | |
23 | char *filename; | |
24 | ||
25 | EntropyReceiveFunc *receive_func; | |
26 | void *opaque; | |
27 | size_t size; | |
28 | }; | |
29 | ||
30 | /** | |
31 | * A simple and incomplete backend to request entropy from /dev/random. | |
32 | * | |
33 | * This backend exposes an additional "filename" property that can be used to | |
34 | * set the filename to use to open the backend. | |
35 | */ | |
36 | ||
37 | static void entropy_available(void *opaque) | |
38 | { | |
39 | RndRandom *s = RNG_RANDOM(opaque); | |
40 | uint8_t buffer[s->size]; | |
41 | ssize_t len; | |
42 | ||
43 | len = read(s->fd, buffer, s->size); | |
44 | g_assert(len != -1); | |
45 | ||
46 | s->receive_func(s->opaque, buffer, len); | |
47 | s->receive_func = NULL; | |
48 | ||
49 | qemu_set_fd_handler(s->fd, NULL, NULL, NULL); | |
50 | } | |
51 | ||
52 | static void rng_random_request_entropy(RngBackend *b, size_t size, | |
53 | EntropyReceiveFunc *receive_entropy, | |
54 | void *opaque) | |
55 | { | |
56 | RndRandom *s = RNG_RANDOM(b); | |
57 | ||
58 | if (s->receive_func) { | |
59 | s->receive_func(s->opaque, NULL, 0); | |
60 | } | |
61 | ||
62 | s->receive_func = receive_entropy; | |
63 | s->opaque = opaque; | |
64 | s->size = size; | |
65 | ||
66 | qemu_set_fd_handler(s->fd, entropy_available, NULL, s); | |
67 | } | |
68 | ||
69 | static void rng_random_opened(RngBackend *b, Error **errp) | |
70 | { | |
71 | RndRandom *s = RNG_RANDOM(b); | |
72 | ||
73 | if (s->filename == NULL) { | |
74 | error_set(errp, QERR_INVALID_PARAMETER_VALUE, | |
75 | "filename", "a valid filename"); | |
76 | } else { | |
77 | s->fd = open(s->filename, O_RDONLY | O_NONBLOCK); | |
78 | ||
79 | if (s->fd == -1) { | |
80 | error_set(errp, QERR_OPEN_FILE_FAILED, s->filename); | |
81 | } | |
82 | } | |
83 | } | |
84 | ||
85 | static char *rng_random_get_filename(Object *obj, Error **errp) | |
86 | { | |
87 | RndRandom *s = RNG_RANDOM(obj); | |
88 | ||
89 | if (s->filename) { | |
90 | return g_strdup(s->filename); | |
91 | } | |
92 | ||
93 | return NULL; | |
94 | } | |
95 | ||
96 | static void rng_random_set_filename(Object *obj, const char *filename, | |
97 | Error **errp) | |
98 | { | |
99 | RngBackend *b = RNG_BACKEND(obj); | |
100 | RndRandom *s = RNG_RANDOM(obj); | |
101 | ||
102 | if (b->opened) { | |
103 | error_set(errp, QERR_PERMISSION_DENIED); | |
104 | return; | |
105 | } | |
106 | ||
107 | if (s->filename) { | |
108 | g_free(s->filename); | |
109 | } | |
110 | ||
111 | s->filename = g_strdup(filename); | |
112 | } | |
113 | ||
114 | static void rng_random_init(Object *obj) | |
115 | { | |
116 | RndRandom *s = RNG_RANDOM(obj); | |
117 | ||
118 | object_property_add_str(obj, "filename", | |
119 | rng_random_get_filename, | |
120 | rng_random_set_filename, | |
121 | NULL); | |
122 | ||
123 | s->filename = g_strdup("/dev/random"); | |
124 | } | |
125 | ||
126 | static void rng_random_finalize(Object *obj) | |
127 | { | |
128 | RndRandom *s = RNG_RANDOM(obj); | |
129 | ||
130 | qemu_set_fd_handler(s->fd, NULL, NULL, NULL); | |
131 | ||
132 | if (s->fd != -1) { | |
133 | close(s->fd); | |
134 | } | |
135 | ||
136 | g_free(s->filename); | |
137 | } | |
138 | ||
139 | static void rng_random_class_init(ObjectClass *klass, void *data) | |
140 | { | |
141 | RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); | |
142 | ||
143 | rbc->request_entropy = rng_random_request_entropy; | |
144 | rbc->opened = rng_random_opened; | |
145 | } | |
146 | ||
147 | static TypeInfo rng_random_info = { | |
148 | .name = TYPE_RNG_RANDOM, | |
149 | .parent = TYPE_RNG_BACKEND, | |
150 | .instance_size = sizeof(RndRandom), | |
151 | .class_init = rng_random_class_init, | |
152 | .instance_init = rng_random_init, | |
153 | .instance_finalize = rng_random_finalize, | |
154 | }; | |
155 | ||
156 | static void register_types(void) | |
157 | { | |
158 | type_register_static(&rng_random_info); | |
159 | } | |
160 | ||
161 | type_init(register_types); |