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, 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); 175