minix/drivers/random/main.c
David van Moolenbroek b4d909d415 Split block/character protocols and libdriver
This patch separates the character and block driver communication
protocols. The old character protocol remains the same, but a new
block protocol is introduced. The libdriver library is replaced by
two new libraries: libchardriver and libblockdriver. Their exposed
API, and drivers that use them, have been updated accordingly.
Together, libbdev and libblockdriver now completely abstract away
the message format used by the block protocol. As the memory driver
is both a character and a block device driver, it now implements its
own message loop.

The most important semantic change made to the block protocol is that
it is no longer possible to return both partial results and an error
for a single transfer. This simplifies the interaction between the
caller and the driver, as the I/O vector no longer needs to be copied
back. Also, drivers are now no longer supposed to decide based on the
layout of the I/O vector when a transfer should be cut short. Put
simply, transfers are now supposed to either succeed completely, or
result in an error.

After this patch, the state of the various pieces is as follows:
- block protocol: stable
- libbdev API: stable for synchronous communication
- libblockdriver API: needs slight revision (the drvlib/partition API
  in particular; the threading API will also change shortly)
- character protocol: needs cleanup
- libchardriver API: needs cleanup accordingly
- driver restarts: largely unsupported until endpoint changes are
  reintroduced

As a side effect, this patch eliminates several bugs, hacks, and gcc
-Wall and -W warnings all over the place. It probably introduces a
few new ones, too.

Update warning: this patch changes the protocol between MFS and disk
drivers, so in order to use old/new images, the MFS from the ramdisk
must be used to mount all file systems.
2011-11-23 14:06:37 +01:00

291 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 */
PRIVATE struct device m_geom[NR_DEVS]; /* base and size of each device */
PRIVATE dev_t m_device; /* current device */
extern int errno; /* error number for PM calls */
FORWARD _PROTOTYPE( struct device *r_prepare, (dev_t device) );
FORWARD _PROTOTYPE( int r_transfer, (endpoint_t endpt, int opcode,
u64_t position, iovec_t *iov, unsigned int nr_req,
endpoint_t user_endpt) );
FORWARD _PROTOTYPE( int r_do_open, (message *m_ptr) );
FORWARD _PROTOTYPE( void r_random, (message *m_ptr) );
FORWARD _PROTOTYPE( void r_updatebin, (int source,
struct k_randomness_bin *rb) );
/* Entry points to this driver. */
PRIVATE 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
PRIVATE char random_buf[RANDOM_BUF_SIZE];
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
FORWARD _PROTOTYPE( int sef_cb_init_fresh, (int type, sef_init_info_t *info) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PRIVATE 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 */
)
{
/* 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, D);
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, D);
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 *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PRIVATE 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;
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(KRANDOM_PERIOD, 0)))
printf("RANDOM: sys_setalarm failed: %d\n", s);
}