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 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, 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_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 } 145 146 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 }; 163 164 static void register_types(void) 165 { 166 type_register_static(&rng_egd_info); 167 } 168 169 type_init(register_types); 170