| 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 "system/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 | CharFrontend chr; |
| 28 | char *chr_name; |
| 29 | }; |
| 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 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 | |
| 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, "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 | |
| 126 | static char *rng_egd_get_chardev(Object *obj, Error **errp) |
| 127 | { |
| 128 | RngEgd *s = RNG_EGD(obj); |
| 129 | return qemu_chr_fe_backend_name(&s->chr); |
| 130 | } |
| 131 | |
| 132 | static void rng_egd_finalize(Object *obj) |
| 133 | { |
| 134 | RngEgd *s = RNG_EGD(obj); |
| 135 | |
| 136 | qemu_chr_fe_deinit(&s->chr, false); |
| 137 | g_free(s->chr_name); |
| 138 | } |
| 139 | |
| 140 | static void rng_egd_class_init(ObjectClass *klass, const void *data) |
| 141 | { |
| 142 | RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); |
| 143 | |
| 144 | rbc->request_entropy = rng_egd_request_entropy; |
| 145 | rbc->opened = rng_egd_opened; |
| 146 | object_class_property_add_str(klass, "chardev", |
| 147 | rng_egd_get_chardev, rng_egd_set_chardev); |
| 148 | } |
| 149 | |
| 150 | static const TypeInfo rng_egd_info = { |
| 151 | .name = TYPE_RNG_EGD, |
| 152 | .parent = TYPE_RNG_BACKEND, |
| 153 | .instance_size = sizeof(RngEgd), |
| 154 | .class_init = rng_egd_class_init, |
| 155 | .instance_finalize = rng_egd_finalize, |
| 156 | }; |
| 157 | |
| 158 | static void register_types(void) |
| 159 | { |
| 160 | type_register_static(&rng_egd_info); |
| 161 | } |
| 162 | |
| 163 | type_init(register_types); |