File size: 5,273 Bytes
2166d7e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 | #include "l0_boot.h"
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/random.h>
#include <unistd.h>
#if defined(__x86_64__) || defined(__i386__)
#include <cpuid.h>
#endif
#include "cs_sha256.h"
cs_status cs_boot_cpu_detect(cs_cpu_info *out)
{
if (!out) return CS_ERR_ARG;
memset(out, 0, sizeof *out);
strcpy(out->vendor, "unknown");
out->word_bits = (int)(sizeof(void *) * 8);
{
const uint16_t probe = 1;
out->little_endian = *(const uint8_t *)&probe == 1;
}
#if defined(__x86_64__)
strcpy(out->arch, "x86_64");
#elif defined(__i386__)
strcpy(out->arch, "i386");
#elif defined(__aarch64__)
strcpy(out->arch, "aarch64");
#elif defined(__riscv)
strcpy(out->arch, "riscv");
#else
strcpy(out->arch, "other");
#endif
#if defined(__x86_64__) || defined(__i386__)
unsigned eax, ebx, ecx, edx;
if (__get_cpuid(0, &eax, &ebx, &ecx, &edx)) {
unsigned maxleaf = eax;
memcpy(out->vendor, &ebx, 4);
memcpy(out->vendor + 4, &edx, 4);
memcpy(out->vendor + 8, &ecx, 4);
out->vendor[12] = '\0';
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
if (edx & (1u << 26)) out->features |= CS_CPU_SSE2;
if (ecx & (1u << 25)) out->features |= CS_CPU_AES;
if (ecx & (1u << 30)) out->features |= CS_CPU_RDRAND;
}
if (maxleaf >= 7 && __get_cpuid_count(7, 0, &eax, &ebx, &ecx, &edx)) {
if (ebx & (1u << 5)) out->features |= CS_CPU_AVX2;
if (ebx & (1u << 29)) out->features |= CS_CPU_SHA;
}
}
#endif
return CS_OK;
}
static int os_entropy(void *buf, size_t n)
{
uint8_t *p = buf;
while (n > 0) {
ssize_t r = getrandom(p, n, 0);
if (r < 0) {
int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
if (fd < 0) return -1;
while (n > 0) {
ssize_t g = read(fd, p, n);
if (g <= 0) { close(fd); return -1; }
p += g; n -= (size_t)g;
}
close(fd);
return 0;
}
p += r; n -= (size_t)r;
}
return 0;
}
static int health_ok(const uint8_t *s, size_t n)
{
size_t run = 1;
int distinct = 0;
for (size_t i = 1; i < n; i++) {
run = (s[i] == s[i - 1]) ? run + 1 : 1;
if (run >= 4) return 0; /* repetition count test */
if (s[i] != s[0]) distinct = 1;
}
return n > 1 && distinct; /* not constant */
}
cs_status cs_boot_entropy(cs_entropy_fn fn, uint8_t *out, size_t n)
{
if (!out || n == 0) return CS_ERR_ARG;
if (!fn) fn = os_entropy;
uint8_t probe[64];
if (fn(probe, sizeof probe) != 0) return CS_ERR_ENTROPY;
int ok = health_ok(probe, sizeof probe);
memset(probe, 0, sizeof probe);
if (!ok) return CS_ERR_ENTROPY;
if (fn(out, n) != 0) return CS_ERR_ENTROPY;
if (n >= 16 && !health_ok(out, n)) return CS_ERR_ENTROPY;
return CS_OK;
}
cs_status cs_memtest_check(volatile const uint64_t *region, size_t words, uint64_t pattern)
{
for (size_t i = 0; i < words; i++)
if (region[i] != pattern) return CS_ERR_MEMTEST;
return CS_OK;
}
static uint64_t unique_word(size_t i)
{
uint64_t x = (uint64_t)i * 0x9E3779B97F4A7C15ull + 0xD1B54A32D192ED03ull;
x ^= x >> 29;
return x * 0xBF58476D1CE4E5B9ull;
}
cs_status cs_memtest_region(volatile uint64_t *region, size_t words)
{
if (!region || words == 0) return CS_ERR_ARG;
static const uint64_t pats[] = {0x0ull, ~0ull, 0xAAAAAAAAAAAAAAAAull, 0x5555555555555555ull};
for (size_t p = 0; p < sizeof pats / sizeof pats[0]; p++) {
for (size_t i = 0; i < words; i++) region[i] = pats[p];
if (cs_memtest_check(region, words, pats[p]) != CS_OK) return CS_ERR_MEMTEST;
}
for (size_t i = 0; i < words; i++) region[i] = unique_word(i);
for (size_t i = 0; i < words; i++)
if (region[i] != unique_word(i)) return CS_ERR_MEMTEST;
return CS_OK;
}
cs_status cs_boot_memory_verify(size_t mem_bytes)
{
size_t words = mem_bytes / sizeof(uint64_t);
if (words == 0) return CS_ERR_ARG;
uint64_t *r = malloc(words * sizeof *r);
if (!r) return CS_ERR_NOMEM;
cs_status s = cs_memtest_region(r, words);
free(r);
return s;
}
cs_status cs_boot_run(cs_boot_report *rep, cs_entropy_fn entropy, size_t mem_bytes)
{
if (!rep) return CS_ERR_ARG;
memset(rep, 0, sizeof *rep);
rep->status = CS_ERR_BOOT;
cs_status s = cs_boot_cpu_detect(&rep->cpu);
if (s != CS_OK) return s;
s = cs_boot_entropy(entropy, rep->seed, sizeof rep->seed);
if (s != CS_OK) { rep->status = s; return s; }
s = cs_boot_memory_verify(mem_bytes);
if (s != CS_OK) { rep->status = s; return s; }
rep->mem_verified_bytes = mem_bytes / sizeof(uint64_t) * sizeof(uint64_t);
cs_sha256_ctx c;
cs_sha256_init(&c);
cs_sha256_update(&c, "cstack-boot-v1", 14);
cs_sha256_update(&c, rep->seed, sizeof rep->seed);
cs_sha256_update(&c, rep->cpu.arch, strlen(rep->cpu.arch));
cs_sha256_update(&c, rep->cpu.vendor, strlen(rep->cpu.vendor));
cs_sha256_update_u64(&c, rep->cpu.features);
cs_sha256_final(&c, rep->boot_id);
rep->status = CS_OK;
return CS_OK;
}
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