drivers/random/main.c

   1 /* This file contains the device dependent part of the drivers for the
   2  * following special files:
   3  *     /dev/random      - random number generator
   4  */
   5
   6 #include <minix/drivers.h>
   7 #include <minix/chardriver.h>
   8 #include <minix/type.h>
   9
  10 #include "assert.h"
  11 #include "random.h"
  12
  13 #define NR_DEVS            1            /* number of minor devices */
  14 #  define RANDOM_DEV  0                 /* minor device for /dev/random */
  15
  16 #define KRANDOM_PERIOD    1             /* ticks between krandom calls */
  17
  18 static struct device m_geom[NR_DEVS];  /* base and size of each device */
  19 static dev_t m_device;                  /* current device */
  20
  21 extern int errno;                       /* error number for PM calls */
  22
  23 static struct device *r_prepare(dev_t device);
  24 static int r_transfer(endpoint_t endpt, int opcode, u64_t position,
  25         iovec_t *iov, unsigned int nr_req, endpoint_t user_endpt, unsigned int
  26         flags);
  27 static int r_do_open(message *m_ptr);
  28 static void r_random(message *m_ptr);
  29 static void r_updatebin(int source, struct k_randomness_bin *rb);
  30
  31 /* Entry points to this driver. */
  32 static struct chardriver r_dtab = {
  33   r_do_open,    /* open or mount */
  34   do_nop,       /* nothing on a close */
  35   nop_ioctl,    /* no I/O controls supported */
  36   r_prepare,    /* prepare for I/O on a given minor device */
  37   r_transfer,   /* do the I/O */
  38   nop_cleanup,  /* no need to clean up */
  39   r_random,     /* get randomness from kernel (alarm) */
  40   nop_cancel,   /* cancel not supported */
  41   nop_select,   /* select not supported */
  42   NULL,         /* other messages not supported */
  43 };
  44
  45 /* Buffer for the /dev/random number generator. */
  46 #define RANDOM_BUF_SIZE                 1024
  47 static char random_buf[RANDOM_BUF_SIZE];
  48
  49 /* SEF functions and variables. */
  50 static void sef_local_startup(void);
  51 static int sef_cb_init_fresh(int type, sef_init_info_t *info);
  52
  53 /*===========================================================================*
  54  *                                 main                                      *
  55  *===========================================================================*/
  56 int main(void)
  57 {
  58   /* SEF local startup. */
  59   sef_local_startup();
  60
  61   /* Call the generic receive loop. */
  62   chardriver_task(&r_dtab, CHARDRIVER_ASYNC);
  63
  64   return(OK);
  65 }
  66
  67 /*===========================================================================*
  68  *                             sef_local_startup                             *
  69  *===========================================================================*/
  70 static void sef_local_startup()
  71 {
  72   /* Register init callbacks. */
  73   sef_setcb_init_fresh(sef_cb_init_fresh);
  74   sef_setcb_init_lu(sef_cb_init_fresh);
  75   sef_setcb_init_restart(sef_cb_init_fresh);
  76
  77   /* Register live update callbacks. */
  78   sef_setcb_lu_prepare(sef_cb_lu_prepare_always_ready);
  79   sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid_standard);
  80
  81   /* Let SEF perform startup. */
  82   sef_startup();
  83 }
  84
  85 /*===========================================================================*
  86  *                          sef_cb_init_fresh                                *
  87  *===========================================================================*/
  88 static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
  89 {
  90 /* Initialize the random driver. */
  91   static struct k_randomness krandom;
  92   int i, s;
  93
  94   random_init();
  95   r_random(NULL);                               /* also set periodic timer */
  96
  97   /* Retrieve first randomness buffer with parameters. */
  98   if (OK != (s=sys_getrandomness(&krandom))) {
  99         printf("RANDOM: sys_getrandomness failed: %d\n", s);
 100         exit(1);
 101   }
 102
 103   /* Do sanity check on parameters. */
 104   if(krandom.random_sources != RANDOM_SOURCES ||
 105      krandom.random_elements != RANDOM_ELEMENTS) {
 106      printf("random: parameters (%d, %d) don't match kernel's (%d, %d)\n",
 107         RANDOM_SOURCES, RANDOM_ELEMENTS,
 108         krandom.random_sources, krandom.random_elements);
 109      exit(1);
 110   }
 111
 112   /* Feed initial batch. */
 113   for(i = 0; i < RANDOM_SOURCES; i++)
 114         r_updatebin(i, &krandom.bin[i]);
 115
 116   /* Announce we are up! */
 117   chardriver_announce();
 118
 119   return(OK);
 120 }
 121
 122 /*===========================================================================*
 123  *                              r_prepare                                    *
 124  *===========================================================================*/
 125 static struct device *r_prepare(dev_t device)
 126 {
 127 /* Prepare for I/O on a device: check if the minor device number is ok. */
 128
 129   if (device >= NR_DEVS) return(NULL);
 130   m_device = device;
 131
 132   return(&m_geom[device]);
 133 }
 134
 135 /*===========================================================================*
 136  *                              r_transfer                                   *
 137  *===========================================================================*/
 138 static int r_transfer(
 139   endpoint_t endpt,             /* endpoint of grant owner */
 140   int opcode,                   /* DEV_GATHER or DEV_SCATTER */
 141   u64_t position,               /* offset on device to read or write */
 142   iovec_t *iov,                 /* pointer to read or write request vector */
 143   unsigned int nr_req,          /* length of request vector */
 144   endpoint_t UNUSED(user_endpt),/* endpoint of user process */
 145   unsigned int UNUSED(flags)
 146 )
 147 {
 148 /* Read or write one the driver's minor devices. */
 149   unsigned count, left, chunk;
 150   cp_grant_id_t grant;
 151   struct device *dv;
 152   int r;
 153   size_t vir_offset = 0;
 154
 155   /* Get minor device number and check for /dev/null. */
 156   dv = &m_geom[m_device];
 157
 158   while (nr_req > 0) {
 159
 160         /* How much to transfer and where to / from. */
 161         count = iov->iov_size;
 162         grant = (cp_grant_id_t) iov->iov_addr;
 163
 164         switch (m_device) {
 165
 166         /* Random number generator. Character instead of block device. */
 167         case RANDOM_DEV:
 168             if (opcode == DEV_GATHER_S && !random_isseeded())
 169                     return(EAGAIN);
 170             left = count;
 171             while (left > 0) {
 172                 chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
 173                 if (opcode == DEV_GATHER_S) {
 174                     random_getbytes(random_buf, chunk);
 175                     r= sys_safecopyto(endpt, grant, vir_offset,
 176                         (vir_bytes) random_buf, chunk);
 177                     if (r != OK)
 178                     {
 179                         printf("random: sys_safecopyto failed for proc %d, "
 180                                 "grant %d\n", endpt, grant);
 181                         return r;
 182                     }
 183                 } else if (opcode == DEV_SCATTER_S) {
 184                     r= sys_safecopyfrom(endpt, grant, vir_offset,
 185                         (vir_bytes) random_buf, chunk);
 186                     if (r != OK)
 187                     {
 188                         printf("random: sys_safecopyfrom failed for proc %d, "
 189                                 "grant %d\n", endpt, grant);
 190                         return r;
 191                     }
 192                     random_putbytes(random_buf, chunk);
 193                 }
 194                 vir_offset += chunk;
 195                 left -= chunk;
 196             }
 197             break;
 198
 199         /* Unknown (illegal) minor device. */
 200         default:
 201             return(EINVAL);
 202         }
 203
 204         /* Book the number of bytes transferred. */
 205         position= add64u(position, count);
 206         if ((iov->iov_size -= count) == 0) { iov++; nr_req--; vir_offset = 0; }
 207
 208   }
 209   return(OK);
 210 }
 211
 212 /*===========================================================================*
 213  *                              r_do_open                                    *
 214  *===========================================================================*/
 215 static int r_do_open(message *m_ptr)
 216 {
 217 /* Check device number on open.
 218  */
 219   if (r_prepare(m_ptr->DEVICE) == NULL) return(ENXIO);
 220
 221   return(OK);
 222 }
 223
 224 #define UPDATE(binnumber, bp, startitem, elems)         {       \
 225                 rand_t *r;                                      \
 226                 int n = elems, item = startitem;\
 227                 int high;                                       \
 228                 assert(binnumber >= 0 && binnumber < RANDOM_SOURCES);    \
 229                 assert(item >= 0 && item < RANDOM_ELEMENTS);    \
 230                 if(n > 0) {                                     \
 231                         high = item+n-1;                        \
 232                         assert(high >= item);                           \
 233                         assert(high >= 0 && high < RANDOM_ELEMENTS);    \
 234                         r = &bp->r_buf[item];           \
 235                         random_update(binnumber, r, n);                 \
 236                 }                                                       \
 237 }
 238
 239 /*===========================================================================*
 240  *                              r_updatebin                                  *
 241  *===========================================================================*/
 242 static void r_updatebin(int source, struct k_randomness_bin *rb)
 243 {
 244         int r_next, r_size, r_high;
 245
 246         r_next= rb->r_next;
 247         r_size= rb->r_size;
 248
 249         assert(r_next >= 0 && r_next < RANDOM_ELEMENTS);
 250         assert(r_size >= 0 && r_size <= RANDOM_ELEMENTS);
 251
 252         r_high= r_next+r_size;
 253
 254         if (r_high <= RANDOM_ELEMENTS) {
 255                 UPDATE(source, rb, r_next, r_size);
 256         } else {
 257                 assert(r_next < RANDOM_ELEMENTS);
 258                 UPDATE(source, rb, r_next, RANDOM_ELEMENTS-r_next);
 259                 UPDATE(source, rb, 0, r_high-RANDOM_ELEMENTS);
 260         }
 261
 262         return;
 263 }
 264
 265 /*===========================================================================*
 266  *                              r_random                                     *
 267  *===========================================================================*/
 268 static void r_random(message *UNUSED(m_ptr))
 269 {
 270   /* Fetch random information from the kernel to update /dev/random. */
 271   int s;
 272   static int bin = 0;
 273   static struct k_randomness_bin krandom_bin;
 274   u32_t hi, lo;
 275   rand_t r;
 276   int nextperiod = random_isseeded() ? KRANDOM_PERIOD*500 : KRANDOM_PERIOD;
 277
 278   bin = (bin+1) % RANDOM_SOURCES;
 279
 280   if(sys_getrandom_bin(&krandom_bin, bin) == OK)
 281         r_updatebin(bin, &krandom_bin);
 282
 283   /* Add our own timing source. */
 284   read_tsc(&hi, &lo);
 285   r = lo;
 286   random_update(RND_TIMING, &r, 1);
 287
 288   /* Schedule new alarm for next m_random call. */
 289   if (OK != (s=sys_setalarm(nextperiod, 0)))
 290         printf("RANDOM: sys_setalarm failed: %d\n", s);
 291 }
 292