jehanne/sys/src/kern/port/random.c

168 lines
3.5 KiB
C

/* Copyright (c) 20XX 9front
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include <libsec.h>
/* machine specific hardware random number generator */
void (*hwrandbuf)(void*, uint32_t) = nil;
static struct
{
QLock;
Chachastate cs;
} *rs;
typedef struct Seedbuf Seedbuf;
struct Seedbuf
{
uint32_t randomcount;
uint8_t buf[64];
uint8_t nbuf;
uint8_t next;
uint16_t bits;
SHA2_512state ds;
};
static void
randomsample(Ureg*_, Timer *t)
{
Seedbuf *s = t->ta;
if(s->randomcount == 0 || s->nbuf >= sizeof(s->buf))
return;
s->bits = (s->bits<<2) ^ s->randomcount;
s->randomcount = 0;
if(++s->next < 8/2)
return;
s->next = 0;
s->buf[s->nbuf++] ^= s->bits;
}
static void
randomseed(void*_)
{
Seedbuf *s;
s = secalloc(sizeof(Seedbuf));
if(hwrandbuf != nil)
(*hwrandbuf)(s->buf, sizeof(s->buf));
/* Frequency close but not equal to HZ */
up->tns = (int64_t)(MS2HZ+3)*1000000LL;
up->tmode = Tperiodic;
up->tt = nil;
up->ta = s;
up->tf = randomsample;
timeradd(up);
while(s->nbuf < sizeof(s->buf)){
if(++s->randomcount <= 100000)
continue;
if(anyhigher())
sched();
}
timerdel(up);
sha2_512(s->buf, sizeof(s->buf), s->buf, &s->ds);
setupChachastate(&rs->cs, s->buf, 32, s->buf+32, 12, 20);
qunlock(rs);
secfree(s);
pexit("", 1);
}
void
randominit(void)
{
rs = secalloc(sizeof(*rs));
qlock(rs); /* randomseed() unlocks once seeded */
kproc("randomseed", randomseed, nil);
}
uint32_t
randomread(void *p, uint32_t n)
{
Chachastate c;
if(n == 0)
return 0;
if(hwrandbuf != nil)
(*hwrandbuf)(p, n);
/* copy chacha state, rekey and increment iv */
qlock(rs);
memmove(&c, &rs->cs, sizeof(c));
chacha_encrypt((uint8_t*)&rs->cs.input[4], 32, &c);
if(++rs->cs.input[13] == 0)
if(++rs->cs.input[14] == 0)
++rs->cs.input[15];
qunlock(rs);
/* encrypt the buffer, can fault */
chacha_encrypt((uint8_t*)p, n, &c);
/* prevent state leakage */
memset(&c, 0, sizeof(c));
return n;
}
/* used by fastrand() */
void
genrandom(uint8_t *p, int n)
{
randomread(p, n);
}
/* used by rand(),nrand() */
long
lrand(void)
{
/* xoroshiro128+ algorithm */
static int seeded = 0;
static uint64_t s[2];
static Lock lk;
uint32_t r;
if(seeded == 0){
randomread(s, sizeof(s));
seeded = (s[0] | s[1]) != 0;
}
lock(&lk);
r = (s[0] + s[1]) >> 33;
s[1] ^= s[0];
s[0] = (s[0] << 55 | s[0] >> 9) ^ s[1] ^ (s[1] << 14);
s[1] = (s[1] << 36 | s[1] >> 28);
unlock(&lk);
return r;
}