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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2019
*/
#include <asm/mem_detect.h>
#include <linux/pgtable.h>
#include <asm/cpacf.h>
#include <asm/timex.h>
#include <asm/sclp.h>
#include "compressed/decompressor.h"
#include "boot.h"
#define PRNG_MODE_TDES 1
#define PRNG_MODE_SHA512 2
#define PRNG_MODE_TRNG 3
struct prno_parm {
u32 res;
u32 reseed_counter;
u64 stream_bytes;
u8 V[112];
u8 C[112];
};
struct prng_parm {
u8 parm_block[32];
u32 reseed_counter;
u64 byte_counter;
};
static int check_prng(void)
{
if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) {
sclp_early_printk("KASLR disabled: CPU has no PRNG\n");
return 0;
}
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
return PRNG_MODE_TRNG;
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN))
return PRNG_MODE_SHA512;
else
return PRNG_MODE_TDES;
}
static unsigned long get_random(unsigned long limit)
{
struct prng_parm prng = {
/* initial parameter block for tdes mode, copied from libica */
.parm_block = {
0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0
},
};
unsigned long seed, random;
struct prno_parm prno;
__u64 entropy[4];
int mode, i;
mode = check_prng();
seed = get_tod_clock_fast();
switch (mode) {
case PRNG_MODE_TRNG:
cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random));
break;
case PRNG_MODE_SHA512:
cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0,
(u8 *) &seed, sizeof(seed));
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random,
sizeof(random), NULL, 0);
break;
case PRNG_MODE_TDES:
/* add entropy */
*(unsigned long *) prng.parm_block ^= seed;
for (i = 0; i < 16; i++) {
cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block,
(u8 *) entropy, (u8 *) entropy,
sizeof(entropy));
memcpy(prng.parm_block, entropy, sizeof(entropy));
}
random = seed;
cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random,
(u8 *) &random, sizeof(random));
break;
default:
random = 0;
}
return random % limit;
}
unsigned long get_random_base(unsigned long safe_addr)
{
unsigned long memory_limit = memory_end_set ? memory_end : 0;
unsigned long base, start, end, kernel_size;
unsigned long block_sum, offset;
unsigned long kasan_needs;
int i;
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE) {
if (safe_addr < INITRD_START + INITRD_SIZE)
safe_addr = INITRD_START + INITRD_SIZE;
}
safe_addr = ALIGN(safe_addr, THREAD_SIZE);
if ((IS_ENABLED(CONFIG_KASAN))) {
/*
* Estimate kasan memory requirements, which it will reserve
* at the very end of available physical memory. To estimate
* that, we take into account that kasan would require
* 1/8 of available physical memory (for shadow memory) +
* creating page tables for the whole memory + shadow memory
* region (1 + 1/8). To keep page tables estimates simple take
* the double of combined ptes size.
*/
memory_limit = get_mem_detect_end();
if (memory_end_set && memory_limit > memory_end)
memory_limit = memory_end;
/* for shadow memory */
kasan_needs = memory_limit / 8;
/* for paging structures */
kasan_needs += (memory_limit + kasan_needs) / PAGE_SIZE /
_PAGE_ENTRIES * _PAGE_TABLE_SIZE * 2;
memory_limit -= kasan_needs;
}
kernel_size = vmlinux.image_size + vmlinux.bss_size;
block_sum = 0;
for_each_mem_detect_block(i, &start, &end) {
if (memory_limit) {
if (start >= memory_limit)
break;
if (end > memory_limit)
end = memory_limit;
}
if (end - start < kernel_size)
continue;
block_sum += end - start - kernel_size;
}
if (!block_sum) {
sclp_early_printk("KASLR disabled: not enough memory\n");
return 0;
}
base = get_random(block_sum);
if (base == 0)
return 0;
if (base < safe_addr)
base = safe_addr;
block_sum = offset = 0;
for_each_mem_detect_block(i, &start, &end) {
if (memory_limit) {
if (start >= memory_limit)
break;
if (end > memory_limit)
end = memory_limit;
}
if (end - start < kernel_size)
continue;
block_sum += end - start - kernel_size;
if (base <= block_sum) {
base = start + base - offset;
base = ALIGN_DOWN(base, THREAD_SIZE);
break;
}
offset = block_sum;
}
return base;
}
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