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/error.h" 17 #include "qapi/qmp/qerror.h" 18 #include "hw/qdev.h" /* just for DEFINE_PROP_CHR */ 19 20 #define TYPE_RNG_EGD "rng-egd" 21 #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD) 22 23 typedef struct RngEgd 24 { 25 RngBackend parent; 26 27 CharDriverState *chr; 28 char *chr_name; 29 } RngEgd; 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 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 s->chr = qemu_chr_find(s->chr_name); 98 if (s->chr == NULL) { 99 error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, 100 "Device '%s' not found", s->chr_name); 101 return; 102 } 103 104 if (qemu_chr_fe_claim(s->chr) != 0) { 105 error_setg(errp, QERR_DEVICE_IN_USE, s->chr_name); 106 return; 107 } 108 109 /* FIXME we should resubmit pending requests when the CDS reconnects. */ 110 qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read, 111 NULL, s); 112 } 113 114 static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp) 115 { 116 RngBackend *b = RNG_BACKEND(obj); 117 RngEgd *s = RNG_EGD(b); 118 119 if (b->opened) { 120 error_setg(errp, QERR_PERMISSION_DENIED); 121 } else { 122 g_free(s->chr_name); 123 s->chr_name = g_strdup(value); 124 } 125 } 126 127 static char *rng_egd_get_chardev(Object *obj, Error **errp) 128 { 129 RngEgd *s = RNG_EGD(obj); 130 131 if (s->chr && s->chr->label) { 132 return g_strdup(s->chr->label); 133 } 134 135 return NULL; 136 } 137 138 static void rng_egd_init(Object *obj) 139 { 140 object_property_add_str(obj, "chardev", 141 rng_egd_get_chardev, rng_egd_set_chardev, 142 NULL); 143 } 144 145 static void rng_egd_finalize(Object *obj) 146 { 147 RngEgd *s = RNG_EGD(obj); 148 149 if (s->chr) { 150 qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL); 151 qemu_chr_fe_release(s->chr); 152 } 153 154 g_free(s->chr_name); 155 } 156 157 static void rng_egd_class_init(ObjectClass *klass, void *data) 158 { 159 RngBackendClass *rbc = RNG_BACKEND_CLASS(klass); 160 161 rbc->request_entropy = rng_egd_request_entropy; 162 rbc->opened = rng_egd_opened; 163 } 164 165 static const TypeInfo rng_egd_info = { 166 .name = TYPE_RNG_EGD, 167 .parent = TYPE_RNG_BACKEND, 168 .instance_size = sizeof(RngEgd), 169 .class_init = rng_egd_class_init, 170 .instance_init = rng_egd_init, 171 .instance_finalize = rng_egd_finalize, 172 }; 173 174 static void register_types(void) 175 { 176 type_register_static(&rng_egd_info); 177 } 178 179 type_init(register_types); 180