minix/drivers/random/main.c
Ben Gras 717425320f kernel, random: adaptive entropy gathering
kernel: stop gathering timestamps once the bin is full per interrupt

random: once seeded, retrieve new entropy at a lower rate

Change-Id: I4ce6081d39274728d82c6889686d1650cfd5fc2e
2013-05-07 17:19:06 +00:00

292 lines
8.6 KiB
C

/* This file contains the device dependent part of the drivers for the
* following special files:
* /dev/random - random number generator
*/
#include <minix/drivers.h>
#include <minix/chardriver.h>
#include <minix/type.h>
#include "assert.h"
#include "random.h"
#define NR_DEVS 1 /* number of minor devices */
# define RANDOM_DEV 0 /* minor device for /dev/random */
#define KRANDOM_PERIOD 1 /* ticks between krandom calls */
static struct device m_geom[NR_DEVS]; /* base and size of each device */
static dev_t m_device; /* current device */
extern int errno; /* error number for PM calls */
static struct device *r_prepare(dev_t device);
static int r_transfer(endpoint_t endpt, int opcode, u64_t position,
iovec_t *iov, unsigned int nr_req, endpoint_t user_endpt, unsigned int
flags);
static int r_do_open(message *m_ptr);
static void r_random(message *m_ptr);
static void r_updatebin(int source, struct k_randomness_bin *rb);
/* Entry points to this driver. */
static struct chardriver r_dtab = {
r_do_open, /* open or mount */
do_nop, /* nothing on a close */
nop_ioctl, /* no I/O controls supported */
r_prepare, /* prepare for I/O on a given minor device */
r_transfer, /* do the I/O */
nop_cleanup, /* no need to clean up */
r_random, /* get randomness from kernel (alarm) */
nop_cancel, /* cancel not supported */
nop_select, /* select not supported */
NULL, /* other messages not supported */
};
/* Buffer for the /dev/random number generator. */
#define RANDOM_BUF_SIZE 1024
static char random_buf[RANDOM_BUF_SIZE];
/* SEF functions and variables. */
static void sef_local_startup(void);
static int sef_cb_init_fresh(int type, sef_init_info_t *info);
/*===========================================================================*
* main *
*===========================================================================*/
int main(void)
{
/* SEF local startup. */
sef_local_startup();
/* Call the generic receive loop. */
chardriver_task(&r_dtab, CHARDRIVER_ASYNC);
return(OK);
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
static void sef_local_startup()
{
/* Register init callbacks. */
sef_setcb_init_fresh(sef_cb_init_fresh);
sef_setcb_init_lu(sef_cb_init_fresh);
sef_setcb_init_restart(sef_cb_init_fresh);
/* Register live update callbacks. */
sef_setcb_lu_prepare(sef_cb_lu_prepare_always_ready);
sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid_standard);
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* sef_cb_init_fresh *
*===========================================================================*/
static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
{
/* Initialize the random driver. */
static struct k_randomness krandom;
int i, s;
random_init();
r_random(NULL); /* also set periodic timer */
/* Retrieve first randomness buffer with parameters. */
if (OK != (s=sys_getrandomness(&krandom))) {
printf("RANDOM: sys_getrandomness failed: %d\n", s);
exit(1);
}
/* Do sanity check on parameters. */
if(krandom.random_sources != RANDOM_SOURCES ||
krandom.random_elements != RANDOM_ELEMENTS) {
printf("random: parameters (%d, %d) don't match kernel's (%d, %d)\n",
RANDOM_SOURCES, RANDOM_ELEMENTS,
krandom.random_sources, krandom.random_elements);
exit(1);
}
/* Feed initial batch. */
for(i = 0; i < RANDOM_SOURCES; i++)
r_updatebin(i, &krandom.bin[i]);
/* Announce we are up! */
chardriver_announce();
return(OK);
}
/*===========================================================================*
* r_prepare *
*===========================================================================*/
static struct device *r_prepare(dev_t device)
{
/* Prepare for I/O on a device: check if the minor device number is ok. */
if (device >= NR_DEVS) return(NULL);
m_device = device;
return(&m_geom[device]);
}
/*===========================================================================*
* r_transfer *
*===========================================================================*/
static int r_transfer(
endpoint_t endpt, /* endpoint of grant owner */
int opcode, /* DEV_GATHER or DEV_SCATTER */
u64_t position, /* offset on device to read or write */
iovec_t *iov, /* pointer to read or write request vector */
unsigned int nr_req, /* length of request vector */
endpoint_t UNUSED(user_endpt),/* endpoint of user process */
unsigned int UNUSED(flags)
)
{
/* Read or write one the driver's minor devices. */
unsigned count, left, chunk;
cp_grant_id_t grant;
struct device *dv;
int r;
size_t vir_offset = 0;
/* Get minor device number and check for /dev/null. */
dv = &m_geom[m_device];
while (nr_req > 0) {
/* How much to transfer and where to / from. */
count = iov->iov_size;
grant = (cp_grant_id_t) iov->iov_addr;
switch (m_device) {
/* Random number generator. Character instead of block device. */
case RANDOM_DEV:
if (opcode == DEV_GATHER_S && !random_isseeded())
return(EAGAIN);
left = count;
while (left > 0) {
chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
if (opcode == DEV_GATHER_S) {
random_getbytes(random_buf, chunk);
r= sys_safecopyto(endpt, grant, vir_offset,
(vir_bytes) random_buf, chunk);
if (r != OK)
{
printf("random: sys_safecopyto failed for proc %d, "
"grant %d\n", endpt, grant);
return r;
}
} else if (opcode == DEV_SCATTER_S) {
r= sys_safecopyfrom(endpt, grant, vir_offset,
(vir_bytes) random_buf, chunk);
if (r != OK)
{
printf("random: sys_safecopyfrom failed for proc %d, "
"grant %d\n", endpt, grant);
return r;
}
random_putbytes(random_buf, chunk);
}
vir_offset += chunk;
left -= chunk;
}
break;
/* Unknown (illegal) minor device. */
default:
return(EINVAL);
}
/* Book the number of bytes transferred. */
position= add64u(position, count);
if ((iov->iov_size -= count) == 0) { iov++; nr_req--; vir_offset = 0; }
}
return(OK);
}
/*===========================================================================*
* r_do_open *
*===========================================================================*/
static int r_do_open(message *m_ptr)
{
/* Check device number on open.
*/
if (r_prepare(m_ptr->DEVICE) == NULL) return(ENXIO);
return(OK);
}
#define UPDATE(binnumber, bp, startitem, elems) { \
rand_t *r; \
int n = elems, item = startitem;\
int high; \
assert(binnumber >= 0 && binnumber < RANDOM_SOURCES); \
assert(item >= 0 && item < RANDOM_ELEMENTS); \
if(n > 0) { \
high = item+n-1; \
assert(high >= item); \
assert(high >= 0 && high < RANDOM_ELEMENTS); \
r = &bp->r_buf[item]; \
random_update(binnumber, r, n); \
} \
}
/*===========================================================================*
* r_updatebin *
*===========================================================================*/
static void r_updatebin(int source, struct k_randomness_bin *rb)
{
int r_next, r_size, r_high;
r_next= rb->r_next;
r_size= rb->r_size;
assert(r_next >= 0 && r_next < RANDOM_ELEMENTS);
assert(r_size >= 0 && r_size <= RANDOM_ELEMENTS);
r_high= r_next+r_size;
if (r_high <= RANDOM_ELEMENTS) {
UPDATE(source, rb, r_next, r_size);
} else {
assert(r_next < RANDOM_ELEMENTS);
UPDATE(source, rb, r_next, RANDOM_ELEMENTS-r_next);
UPDATE(source, rb, 0, r_high-RANDOM_ELEMENTS);
}
return;
}
/*===========================================================================*
* r_random *
*===========================================================================*/
static void r_random(message *UNUSED(m_ptr))
{
/* Fetch random information from the kernel to update /dev/random. */
int s;
static int bin = 0;
static struct k_randomness_bin krandom_bin;
u32_t hi, lo;
rand_t r;
int nextperiod = random_isseeded() ? KRANDOM_PERIOD*500 : KRANDOM_PERIOD;
bin = (bin+1) % RANDOM_SOURCES;
if(sys_getrandom_bin(&krandom_bin, bin) == OK)
r_updatebin(bin, &krandom_bin);
/* Add our own timing source. */
read_tsc(&hi, &lo);
r = lo;
random_update(RND_TIMING, &r, 1);
/* Schedule new alarm for next m_random call. */
if (OK != (s=sys_setalarm(nextperiod, 0)))
printf("RANDOM: sys_setalarm failed: %d\n", s);
}