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Make uniqids truly random

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This commit is contained in:
Kamil Kowalczyk
2025-10-11 21:36:50 +02:00
parent b717387adb
commit d92a652024
1 changed files with 22 additions and 9 deletions
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31
kernel/randcrypto/uniqid.c
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@ -3,6 +3,7 @@
#include "uniqid.h"
#include "atomic.h"
#include "spinlock/spinlock.h"
#include "hal/hal.h"
static const char *base62 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@ -22,6 +23,22 @@ uint32_t uniqmix32(uint32_t x) {
return x;
}
void uniqseed(void) {
if (uniqstate != 0u)
return;
uint32_t seed = 0;
int32_t r = hal_randnum();
if (r != -1) {
seed = (uint32_t)r;
} else {
uintptr_t p = (uintptr_t)(void *)&uniqstate;
seed = (uint32_t)(p ^ (p>>32)) ^ 0x9E3779B9u;
}
uniqstate = seed ? seed : 1u;
}
void randcrypto_gen_uniqid(char *out, size_t n) {
if (!out || n == 0) {
return;
@ -29,14 +46,10 @@ void randcrypto_gen_uniqid(char *out, size_t n) {
spinlock_acquire(&uniqstate_spinlock);
if (uniqstate == 0u) {
uintptr_t p = (uintptr_t)(void *)&uniqstate;
uint32_t seed = (uint32_t)(p ^ (p >> 16));
uniqstate = seed ^ 0x9E3779B9u;
if (uniqstate == 0u) {
uniqstate = 1u;
}
}
uniqseed();
int32_t r = hal_randnum();
uint32_t extra = (r != -1) ? (uint32_t)r : uniqstate * 0x27d4eb2dU;
uniqstate += 0x9E3779B1u;
uint32_t v = uniqmix32(uniqstate);
@ -44,7 +57,7 @@ void randcrypto_gen_uniqid(char *out, size_t n) {
spinlock_release(&uniqstate_spinlock);
for (size_t i = 0; i < n; i++) {
v = uniqmix32(v + i * 0x27d4eb2dU);
v = uniqmix32(v + i * 0x85ebca6bU);
out[i] = base62[v % 62u];
}
out[n] = '\0';