minix/drivers/random/main.c

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/* This file contains the device dependent part of the drivers for the
* following special files:
* /dev/random - random number generator
*/
#include "../drivers.h"
#include "../libdriver/driver.h"
#include <sys/ioc_memory.h>
#include "../../kernel/const.h"
#include "../../kernel/config.h"
#include "../../kernel/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 */
PRIVATE struct device m_geom[NR_DEVS]; /* base and size of each device */
PRIVATE int m_device; /* current device */
extern int errno; /* error number for PM calls */
FORWARD _PROTOTYPE( char *r_name, (void) );
FORWARD _PROTOTYPE( struct device *r_prepare, (int device) );
FORWARD _PROTOTYPE( int r_transfer, (int proc_nr, int opcode, u64_t position,
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iovec_t *iov, unsigned nr_req, int safe) );
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FORWARD _PROTOTYPE( int r_do_open, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( void r_init, (void) );
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FORWARD _PROTOTYPE( int r_ioctl, (struct driver *dp, message *m_ptr, int safe) );
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FORWARD _PROTOTYPE( void r_geometry, (struct partition *entry) );
FORWARD _PROTOTYPE( void r_random, (struct driver *dp, message *m_ptr) );
/* Entry points to this driver. */
PRIVATE struct driver r_dtab = {
r_name, /* current device's name */
r_do_open, /* open or mount */
do_nop, /* nothing on a close */
r_ioctl, /* specify ram disk geometry */
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_geometry, /* device "geometry" */
nop_signal, /* system signals */
r_random, /* get randomness from kernel (alarm) */
nop_cancel,
nop_select,
NULL,
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NULL
};
/* Buffer for the /dev/random number generator. */
#define RANDOM_BUF_SIZE 1024
PRIVATE char random_buf[RANDOM_BUF_SIZE];
/*===========================================================================*
* main *
*===========================================================================*/
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PUBLIC int main(void)
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{
r_init(); /* initialize the memory driver */
driver_task(&r_dtab); /* start driver's main loop */
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return(OK);
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}
/*===========================================================================*
* r_name *
*===========================================================================*/
PRIVATE char *r_name()
{
/* Return a name for the current device. */
static char name[] = "random";
return name;
}
/*===========================================================================*
* r_prepare *
*===========================================================================*/
PRIVATE struct device *r_prepare(device)
int device;
{
/* Prepare for I/O on a device: check if the minor device number is ok. */
if (device < 0 || device >= NR_DEVS) return(NIL_DEV);
m_device = device;
return(&m_geom[device]);
}
/*===========================================================================*
* r_transfer *
*===========================================================================*/
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PRIVATE int r_transfer(proc_nr, opcode, position, iov, nr_req, safe)
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int proc_nr; /* process doing the request */
int opcode; /* DEV_GATHER or DEV_SCATTER */
u64_t position; /* offset on device to read or write */
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iovec_t *iov; /* pointer to read or write request vector */
unsigned nr_req; /* length of request vector */
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int safe; /* safe copies? */
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{
/* Read or write one the driver's minor devices. */
unsigned count, left, chunk;
vir_bytes user_vir;
struct device *dv;
unsigned long dv_size;
int r;
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size_t vir_offset = 0;
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/* Get minor device number and check for /dev/null. */
dv = &m_geom[m_device];
dv_size = cv64ul(dv->dv_size);
while (nr_req > 0) {
/* How much to transfer and where to / from. */
count = iov->iov_size;
user_vir = iov->iov_addr;
switch (m_device) {
/* Random number generator. Character instead of block device. */
case RANDOM_DEV:
if (opcode == DEV_GATHER && !random_isseeded())
return(EAGAIN);
left = count;
while (left > 0) {
chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
if (opcode == DEV_GATHER) {
random_getbytes(random_buf, chunk);
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if(safe) {
r= sys_safecopyto(proc_nr, user_vir, vir_offset,
(vir_bytes) random_buf, chunk, D);
if (r != OK)
{
printf(
"random: sys_safecopyto failed for proc %d, grant %d\n",
proc_nr, user_vir);
return r;
}
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} else {
sys_vircopy(SELF, D, (vir_bytes) random_buf,
proc_nr, D, user_vir + vir_offset, chunk);
}
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} else if (opcode == DEV_SCATTER) {
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if(safe) {
r= sys_safecopyfrom(proc_nr, user_vir, vir_offset,
(vir_bytes) random_buf, chunk, D);
if (r != OK)
{
printf(
"random: sys_safecopyfrom failed for proc %d, grant %d\n",
proc_nr, user_vir);
return r;
}
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} else {
sys_vircopy(proc_nr, D, user_vir + vir_offset,
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SELF, D, (vir_bytes) random_buf, chunk);
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}
random_putbytes(random_buf, chunk);
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}
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vir_offset += chunk;
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left -= chunk;
}
break;
/* Unknown (illegal) minor device. */
default:
return(EINVAL);
}
/* Book the number of bytes transferred. */
position= add64u(position, count);
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if ((iov->iov_size -= count) == 0) { iov++; nr_req--; vir_offset = 0; }
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}
return(OK);
}
/*============================================================================*
* r_do_open *
*============================================================================*/
PRIVATE int r_do_open(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
/* Check device number on open.
*/
if (r_prepare(m_ptr->DEVICE) == NIL_DEV) return(ENXIO);
return(OK);
}
/*===========================================================================*
* r_init *
*===========================================================================*/
PRIVATE void r_init()
{
/* Initialize this task. All minor devices are initialized one by one. */
random_init();
r_random(NULL, NULL); /* also set periodic timer */
}
/*===========================================================================*
* r_ioctl *
*===========================================================================*/
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PRIVATE int r_ioctl(dp, m_ptr, safe)
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struct driver *dp; /* pointer to driver structure */
message *m_ptr; /* pointer to control message */
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int safe; /* safe i/o? */
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{
struct device *dv;
if ((dv = r_prepare(m_ptr->DEVICE)) == NIL_DEV) return(ENXIO);
switch (m_ptr->REQUEST) {
default:
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return(do_diocntl(&r_dtab, m_ptr, safe));
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}
return(OK);
}
/*============================================================================*
* r_random *
*============================================================================*/
PRIVATE void r_random(dp, m_ptr)
struct driver *dp; /* pointer to driver structure */
message *m_ptr; /* pointer to alarm message */
{
/* Fetch random information from the kernel to update /dev/random. */
int i, s, r_next, r_size, r_high;
struct randomness krandom;
if (OK != (s=sys_getrandomness(&krandom)))
report("RANDOM", "sys_getrandomness failed", s);
for (i= 0; i<RANDOM_SOURCES; i++)
{
r_next= krandom.bin[i].r_next;
r_size= krandom.bin[i].r_size;
r_high= r_next+r_size;
if (r_high <= RANDOM_ELEMENTS)
{
random_update(i, &krandom.bin[i].r_buf[r_next], r_size);
}
else
{
assert(r_next < RANDOM_ELEMENTS);
random_update(i, &krandom.bin[i].r_buf[r_next],
RANDOM_ELEMENTS-r_next);
random_update(i, &krandom.bin[i].r_buf[0],
r_high-RANDOM_ELEMENTS);
}
}
/* Schedule new alarm for next m_random call. */
if (OK != (s=sys_setalarm(KRANDOM_PERIOD, 0)))
report("RANDOM", "sys_setalarm failed", s);
}
/*============================================================================*
* r_geometry *
*============================================================================*/
PRIVATE void r_geometry(entry)
struct partition *entry;
{
/* Memory devices don't have a geometry, but the outside world insists. */
entry->cylinders = div64u(m_geom[m_device].dv_size, SECTOR_SIZE) / (64 * 32);
entry->heads = 64;
entry->sectors = 32;
}