Commit 6c4e9d48 authored by Laurent Vivier's avatar Laurent Vivier Committed by Michael S. Tsirkin
Browse files

rng-builtin: add an RNG backend that uses qemu_guest_getrandom() 



Add a new RNG backend using QEMU builtin getrandom function.

It can be created and used with something like:

    ... -object rng-builtin,id=rng0 -device virtio-rng,rng=rng0 ...

Signed-off-by: default avatarLaurent Vivier <lvivier@redhat.com>
Message-Id: <20190820160615.14616-2-lvivier@redhat.com>
parent 379d83f2

backends/Makefile.objs

+1 −1
Original line number Diff line number Diff line 
common-obj-y += rng.o rng-egd.o

common-obj-y += rng.o rng-egd.o rng-builtin.o

common-obj-$(CONFIG_POSIX) += rng-random.o



common-obj-$(CONFIG_TPM) += tpm.o

backends/rng-builtin.c

0 → 100644
+78 −0
Original line number Diff line number Diff line 
/*

 * QEMU Builtin Random Number Generator Backend

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */



#include "qemu/osdep.h"

#include "sysemu/rng.h"

#include "qemu/main-loop.h"

#include "qemu/guest-random.h"



#define TYPE_RNG_BUILTIN "rng-builtin"

#define RNG_BUILTIN(obj) OBJECT_CHECK(RngBuiltin, (obj), TYPE_RNG_BUILTIN)



typedef struct RngBuiltin {

    RngBackend parent;

    QEMUBH *bh;

} RngBuiltin;



static void rng_builtin_receive_entropy_bh(void *opaque)

{

    RngBuiltin *s = opaque;



    while (!QSIMPLEQ_EMPTY(&s->parent.requests)) {

        RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);



        qemu_guest_getrandom_nofail(req->data, req->size);



        req->receive_entropy(req->opaque, req->data, req->size);



        rng_backend_finalize_request(&s->parent, req);

    }

}



static void rng_builtin_request_entropy(RngBackend *b, RngRequest *req)

{

    RngBuiltin *s = RNG_BUILTIN(b);



    qemu_bh_schedule(s->bh);

}



static void rng_builtin_init(Object *obj)

{

    RngBuiltin *s = RNG_BUILTIN(obj);



    s->bh = qemu_bh_new(rng_builtin_receive_entropy_bh, s);

}



static void rng_builtin_finalize(Object *obj)

{

    RngBuiltin *s = RNG_BUILTIN(obj);



    qemu_bh_delete(s->bh);

}



static void rng_builtin_class_init(ObjectClass *klass, void *data)

{

    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);



    rbc->request_entropy = rng_builtin_request_entropy;

}



static const TypeInfo rng_builtin_info = {

    .name = TYPE_RNG_BUILTIN,

    .parent = TYPE_RNG_BACKEND,

    .instance_size = sizeof(RngBuiltin),

    .instance_init = rng_builtin_init,

    .instance_finalize = rng_builtin_finalize,

    .class_init = rng_builtin_class_init,

};



static void register_types(void)

{

    type_register_static(&rng_builtin_info);

}



type_init(register_types);

qemu-options.hx

+7 −0
Original line number Diff line number Diff line
@@ -4332,6 +4332,13 @@ other options. 


The @option{share} boolean option is @var{on} by default with memfd.



@item -object rng-builtin,id=@var{id}



Creates a random number generator backend which obtains entropy from

QEMU builtin functions. The @option{id} parameter is a unique ID that

will be used to reference this entropy backend from the @option{virtio-rng}

device.



@item -object rng-random,id=@var{id},filename=@var{/dev/random}



Creates a random number generator backend which obtains entropy from