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 "sysemu/char.h" 16 #include "qapi/qmp/qerror.h" 17 #include "hw/qdev.h" /* just for DEFINE_PROP_CHR */ 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 CharDriverState *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 qemu_chr_fe_write(s->chr, header, sizeof(header)); 44 45 size -= len; 46 } 47 } 48 49 static int rng_egd_chr_can_read(void *opaque) 50 { 51 RngEgd *s = RNG_EGD(opaque); 52 RngRequest *req; 53 int size = 0; 54 55 QSIMPLEQ_FOREACH(req, &s->parent.requests, next) { 56 size += req->size - req->offset; 57 } 58 59 return size; 60 } 61 62 static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size) 63 { 64 RngEgd *s = RNG_EGD(opaque); 65 size_t buf_offset = 0; 66 67 while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) { 68 RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests); 69 int len = MIN(size, req->size - req->offset); 70 71 memcpy(req->data + req->offset, buf + buf_offset, len); 72 buf_offset += len; 73 req->offset += len; 74 size -= len; 75 76 if (req->offset == req->size) { 77 req->receive_entropy(req->opaque, req->data, req->size); 78 79 rng_backend_finalize_request(&s->parent, req); 80 } 81 } 82 } 83 84 static void rng_egd_opened(RngBackend *b, Error **errp) 85 { 86 RngEgd *s = RNG_EGD(b); 87 88 if (s->chr_name == NULL) { 89 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, 90 "chardev", "a valid character device"); 91 return; 92 } 93 94 s->chr = qemu_chr_find(s->chr_name); 95 if (s->chr == NULL) { 96 error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, 97 "Device '%s' not found", s->chr_name); 98 return; 99 } 100 101 if (qemu_chr_fe_claim(s->chr) != 0) { 102 error_setg(errp, QERR_DEVICE_IN_USE, s->chr_name); 103 return; 104 } 105 106 /* FIXME we should resubmit pending requests when the CDS reconnects. */ 107 qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read, 108 NULL, s); 109 } 110 111 static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp) 112 { 113 RngBackend *b = RNG_BACKEND(obj); 114 RngEgd *s = RNG_EGD(b); 115 116 if (b->opened) { 117 error_setg(errp, QERR_PERMISSION_DENIED); 118 } else { 119 g_free(s->chr_name); 120 s->chr_name = g_strdup(value); 121 } 122 } 123 124 static char *rng_egd_get_chardev(Object *obj, Error **errp) 125 { 126 RngEgd *s = RNG_EGD(obj); 127 128 if (s->chr && s->chr->label) { 129 return g_strdup(s->chr->label); 130 } 131 132 return NULL; 133 } 134 135 static void rng_egd_init(Object *obj) 136 { 137 object_property_add_str(obj, "chardev", 138 rng_egd_get_chardev, rng_egd_set_chardev, 139 NULL); 140 } 141 142 static void rng_egd_finalize(Object *obj) 143 { 144 RngEgd *s = RNG_EGD(obj); 145 146 if (s->chr) { 147 qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL); 148 qemu_chr_fe_release(s->chr); 149 } 150 151 g_free(s->chr_name); 152 } 153 154 static void rng_egd_class_init(ObjectClass *klass, void *data) 155 { 156 RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); 157 158 rbc->request_entropy = rng_egd_request_entropy; 159 rbc->opened = rng_egd_opened; 160 } 161 162 static const TypeInfo rng_egd_info = { 163 .name = TYPE_RNG_EGD, 164 .parent = TYPE_RNG_BACKEND, 165 .instance_size = sizeof(RngEgd), 166 .class_init = rng_egd_class_init, 167 .instance_init = rng_egd_init, 168 .instance_finalize = rng_egd_finalize, 169 }; 170 171 static void register_types(void) 172 { 173 type_register_static(&rng_egd_info); 174 } 175 176 type_init(register_types); 177