mirror of
https://github.com/torvalds/linux.git
synced 2024-12-27 05:11:48 +00:00
f7f510ec19
Note that by itself, having a "hardware" random generator does very little: you should probably run "rngd" in your guest to feed this into the kernel entropy pool. Included: virtio_rng: dont use vmalloced addresses for virtio If virtio_rng is build as a module, random_data is an address in vmalloc space. As virtio expects guest real addresses, this can cause any kind of funny behaviour, so lets allocate random_data dynamically with kmalloc. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
156 lines
3.6 KiB
C
156 lines
3.6 KiB
C
/*
|
|
* Randomness driver for virtio
|
|
* Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
#include <linux/err.h>
|
|
#include <linux/hw_random.h>
|
|
#include <linux/scatterlist.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/virtio.h>
|
|
#include <linux/virtio_rng.h>
|
|
|
|
/* The host will fill any buffer we give it with sweet, sweet randomness. We
|
|
* give it 64 bytes at a time, and the hwrng framework takes it 4 bytes at a
|
|
* time. */
|
|
#define RANDOM_DATA_SIZE 64
|
|
|
|
static struct virtqueue *vq;
|
|
static u32 *random_data;
|
|
static unsigned int data_left;
|
|
static DECLARE_COMPLETION(have_data);
|
|
|
|
static void random_recv_done(struct virtqueue *vq)
|
|
{
|
|
int len;
|
|
|
|
/* We never get spurious callbacks. */
|
|
if (!vq->vq_ops->get_buf(vq, &len))
|
|
BUG();
|
|
|
|
data_left = len / sizeof(random_data[0]);
|
|
complete(&have_data);
|
|
}
|
|
|
|
static void register_buffer(void)
|
|
{
|
|
struct scatterlist sg;
|
|
|
|
sg_init_one(&sg, random_data, RANDOM_DATA_SIZE);
|
|
/* There should always be room for one buffer. */
|
|
if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) != 0)
|
|
BUG();
|
|
vq->vq_ops->kick(vq);
|
|
}
|
|
|
|
/* At least we don't udelay() in a loop like some other drivers. */
|
|
static int virtio_data_present(struct hwrng *rng, int wait)
|
|
{
|
|
if (data_left)
|
|
return 1;
|
|
|
|
if (!wait)
|
|
return 0;
|
|
|
|
wait_for_completion(&have_data);
|
|
return 1;
|
|
}
|
|
|
|
/* virtio_data_present() must have succeeded before this is called. */
|
|
static int virtio_data_read(struct hwrng *rng, u32 *data)
|
|
{
|
|
BUG_ON(!data_left);
|
|
|
|
*data = random_data[--data_left];
|
|
|
|
if (!data_left) {
|
|
init_completion(&have_data);
|
|
register_buffer();
|
|
}
|
|
return sizeof(*data);
|
|
}
|
|
|
|
static struct hwrng virtio_hwrng = {
|
|
.name = "virtio",
|
|
.data_present = virtio_data_present,
|
|
.data_read = virtio_data_read,
|
|
};
|
|
|
|
static int virtrng_probe(struct virtio_device *vdev)
|
|
{
|
|
int err;
|
|
|
|
/* We expect a single virtqueue. */
|
|
vq = vdev->config->find_vq(vdev, 0, random_recv_done);
|
|
if (IS_ERR(vq))
|
|
return PTR_ERR(vq);
|
|
|
|
err = hwrng_register(&virtio_hwrng);
|
|
if (err) {
|
|
vdev->config->del_vq(vq);
|
|
return err;
|
|
}
|
|
|
|
register_buffer();
|
|
return 0;
|
|
}
|
|
|
|
static void virtrng_remove(struct virtio_device *vdev)
|
|
{
|
|
vdev->config->reset(vdev);
|
|
hwrng_unregister(&virtio_hwrng);
|
|
vdev->config->del_vq(vq);
|
|
}
|
|
|
|
static struct virtio_device_id id_table[] = {
|
|
{ VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
|
|
{ 0 },
|
|
};
|
|
|
|
static struct virtio_driver virtio_rng = {
|
|
.driver.name = KBUILD_MODNAME,
|
|
.driver.owner = THIS_MODULE,
|
|
.id_table = id_table,
|
|
.probe = virtrng_probe,
|
|
.remove = __devexit_p(virtrng_remove),
|
|
};
|
|
|
|
static int __init init(void)
|
|
{
|
|
int err;
|
|
|
|
random_data = kmalloc(RANDOM_DATA_SIZE, GFP_KERNEL);
|
|
if (!random_data)
|
|
return -ENOMEM;
|
|
|
|
err = register_virtio_driver(&virtio_rng);
|
|
if (err)
|
|
kfree(random_data);
|
|
return err;
|
|
}
|
|
|
|
static void __exit fini(void)
|
|
{
|
|
kfree(random_data);
|
|
unregister_virtio_driver(&virtio_rng);
|
|
}
|
|
module_init(init);
|
|
module_exit(fini);
|
|
|
|
MODULE_DEVICE_TABLE(virtio, id_table);
|
|
MODULE_DESCRIPTION("Virtio random number driver");
|
|
MODULE_LICENSE("GPL");
|