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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include <assert.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <signal.h>
#include <sys/auxv.h>
#include <sys/mman.h>
#include <sys/random.h>
#include <sys/syscall.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <linux/random.h>
#include <linux/compiler.h>
#include <linux/ptrace.h>
#include "../kselftest.h"
#include "parse_vdso.h"
#include "vdso_config.h"
#include "vdso_call.h"
#ifndef timespecsub
#define timespecsub(tsp, usp, vsp) \
do { \
(vsp)->tv_sec = (tsp)->tv_sec - (usp)->tv_sec; \
(vsp)->tv_nsec = (tsp)->tv_nsec - (usp)->tv_nsec; \
if ((vsp)->tv_nsec < 0) { \
(vsp)->tv_sec--; \
(vsp)->tv_nsec += 1000000000L; \
} \
} while (0)
#endif
static struct {
pthread_mutex_t lock;
void **states;
size_t len, cap;
ssize_t(*fn)(void *, size_t, unsigned long, void *, size_t);
struct vgetrandom_opaque_params params;
} vgrnd = {
.lock = PTHREAD_MUTEX_INITIALIZER
};
static void *vgetrandom_get_state(void)
{
void *state = NULL;
pthread_mutex_lock(&vgrnd.lock);
if (!vgrnd.len) {
size_t page_size = getpagesize();
size_t new_cap;
size_t alloc_size, num = sysconf(_SC_NPROCESSORS_ONLN); /* Just a decent heuristic. */
void *new_block, *new_states;
alloc_size = (num * vgrnd.params.size_of_opaque_state + page_size - 1) & (~(page_size - 1));
num = (page_size / vgrnd.params.size_of_opaque_state) * (alloc_size / page_size);
new_block = mmap(0, alloc_size, vgrnd.params.mmap_prot, vgrnd.params.mmap_flags, -1, 0);
if (new_block == MAP_FAILED)
goto out;
new_cap = vgrnd.cap + num;
new_states = reallocarray(vgrnd.states, new_cap, sizeof(*vgrnd.states));
if (!new_states)
goto unmap;
vgrnd.cap = new_cap;
vgrnd.states = new_states;
for (size_t i = 0; i < num; ++i) {
if (((uintptr_t)new_block & (page_size - 1)) + vgrnd.params.size_of_opaque_state > page_size)
new_block = (void *)(((uintptr_t)new_block + page_size - 1) & (~(page_size - 1)));
vgrnd.states[i] = new_block;
new_block += vgrnd.params.size_of_opaque_state;
}
vgrnd.len = num;
goto success;
unmap:
munmap(new_block, alloc_size);
goto out;
}
success:
state = vgrnd.states[--vgrnd.len];
out:
pthread_mutex_unlock(&vgrnd.lock);
return state;
}
static void vgetrandom_put_state(void *state)
{
if (!state)
return;
pthread_mutex_lock(&vgrnd.lock);
vgrnd.states[vgrnd.len++] = state;
pthread_mutex_unlock(&vgrnd.lock);
}
static void vgetrandom_init(void)
{
const char *version = versions[VDSO_VERSION];
const char *name = names[VDSO_NAMES][6];
unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
size_t ret;
if (!sysinfo_ehdr) {
printf("AT_SYSINFO_EHDR is not present!\n");
exit(KSFT_SKIP);
}
vdso_init_from_sysinfo_ehdr(sysinfo_ehdr);
vgrnd.fn = (__typeof__(vgrnd.fn))vdso_sym(version, name);
if (!vgrnd.fn) {
printf("%s is missing!\n", name);
exit(KSFT_FAIL);
}
ret = VDSO_CALL(vgrnd.fn, 5, NULL, 0, 0, &vgrnd.params, ~0UL);
if (ret == -ENOSYS) {
printf("unsupported architecture\n");
exit(KSFT_SKIP);
} else if (ret) {
printf("failed to fetch vgetrandom params!\n");
exit(KSFT_FAIL);
}
}
static ssize_t vgetrandom(void *buf, size_t len, unsigned long flags)
{
static __thread void *state;
if (!state) {
state = vgetrandom_get_state();
if (!state) {
printf("vgetrandom_get_state failed!\n");
exit(KSFT_FAIL);
}
}
return VDSO_CALL(vgrnd.fn, 5, buf, len, flags, state, vgrnd.params.size_of_opaque_state);
}
enum { TRIALS = 25000000, THREADS = 256 };
static void *test_vdso_getrandom(void *ctx)
{
for (size_t i = 0; i < TRIALS; ++i) {
unsigned int val;
ssize_t ret = vgetrandom(&val, sizeof(val), 0);
assert(ret == sizeof(val));
}
return NULL;
}
static void *test_libc_getrandom(void *ctx)
{
for (size_t i = 0; i < TRIALS; ++i) {
unsigned int val;
ssize_t ret = getrandom(&val, sizeof(val), 0);
assert(ret == sizeof(val));
}
return NULL;
}
static void *test_syscall_getrandom(void *ctx)
{
for (size_t i = 0; i < TRIALS; ++i) {
unsigned int val;
ssize_t ret = syscall(__NR_getrandom, &val, sizeof(val), 0);
assert(ret == sizeof(val));
}
return NULL;
}
static void bench_single(void)
{
struct timespec start, end, diff;
clock_gettime(CLOCK_MONOTONIC, &start);
test_vdso_getrandom(NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf(" vdso: %u times in %lu.%09lu seconds\n", TRIALS, diff.tv_sec, diff.tv_nsec);
clock_gettime(CLOCK_MONOTONIC, &start);
test_libc_getrandom(NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf(" libc: %u times in %lu.%09lu seconds\n", TRIALS, diff.tv_sec, diff.tv_nsec);
clock_gettime(CLOCK_MONOTONIC, &start);
test_syscall_getrandom(NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf("syscall: %u times in %lu.%09lu seconds\n", TRIALS, diff.tv_sec, diff.tv_nsec);
}
static void bench_multi(void)
{
struct timespec start, end, diff;
pthread_t threads[THREADS];
clock_gettime(CLOCK_MONOTONIC, &start);
for (size_t i = 0; i < THREADS; ++i)
assert(pthread_create(&threads[i], NULL, test_vdso_getrandom, NULL) == 0);
for (size_t i = 0; i < THREADS; ++i)
pthread_join(threads[i], NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf(" vdso: %u x %u times in %lu.%09lu seconds\n", TRIALS, THREADS, diff.tv_sec, diff.tv_nsec);
clock_gettime(CLOCK_MONOTONIC, &start);
for (size_t i = 0; i < THREADS; ++i)
assert(pthread_create(&threads[i], NULL, test_libc_getrandom, NULL) == 0);
for (size_t i = 0; i < THREADS; ++i)
pthread_join(threads[i], NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf(" libc: %u x %u times in %lu.%09lu seconds\n", TRIALS, THREADS, diff.tv_sec, diff.tv_nsec);
clock_gettime(CLOCK_MONOTONIC, &start);
for (size_t i = 0; i < THREADS; ++i)
assert(pthread_create(&threads[i], NULL, test_syscall_getrandom, NULL) == 0);
for (size_t i = 0; i < THREADS; ++i)
pthread_join(threads[i], NULL);
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &diff);
printf(" syscall: %u x %u times in %lu.%09lu seconds\n", TRIALS, THREADS, diff.tv_sec, diff.tv_nsec);
}
static void fill(void)
{
uint8_t weird_size[323929];
for (;;)
vgetrandom(weird_size, sizeof(weird_size), 0);
}
static void kselftest(void)
{
uint8_t weird_size[1263];
pid_t child;
ksft_print_header();
ksft_set_plan(2);
for (size_t i = 0; i < 1000; ++i) {
ssize_t ret = vgetrandom(weird_size, sizeof(weird_size), 0);
if (ret != sizeof(weird_size))
exit(KSFT_FAIL);
}
ksft_test_result_pass("getrandom: PASS\n");
unshare(CLONE_NEWUSER);
assert(unshare(CLONE_NEWTIME) == 0);
child = fork();
assert(child >= 0);
if (!child) {
vgetrandom_init();
child = getpid();
assert(ptrace(PTRACE_TRACEME, 0, NULL, NULL) == 0);
assert(kill(child, SIGSTOP) == 0);
assert(vgetrandom(weird_size, sizeof(weird_size), 0) == sizeof(weird_size));
_exit(0);
}
for (;;) {
struct ptrace_syscall_info info = { 0 };
int status, ret;
assert(waitpid(child, &status, 0) >= 0);
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != 0)
exit(KSFT_FAIL);
break;
}
assert(WIFSTOPPED(status));
if (WSTOPSIG(status) == SIGSTOP)
assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD) == 0);
else if (WSTOPSIG(status) == (SIGTRAP | 0x80)) {
assert(ptrace(PTRACE_GET_SYSCALL_INFO, child, sizeof(info), &info) > 0);
if (info.op == PTRACE_SYSCALL_INFO_ENTRY && info.entry.nr == __NR_getrandom &&
info.entry.args[0] == (uintptr_t)weird_size && info.entry.args[1] == sizeof(weird_size))
exit(KSFT_FAIL);
}
assert(ptrace(PTRACE_SYSCALL, child, 0, 0) == 0);
}
ksft_test_result_pass("getrandom timens: PASS\n");
exit(KSFT_PASS);
}
static void usage(const char *argv0)
{
fprintf(stderr, "Usage: %s [bench-single|bench-multi|fill]\n", argv0);
}
int main(int argc, char *argv[])
{
vgetrandom_init();
if (argc == 1) {
kselftest();
return 0;
}
if (argc != 2) {
usage(argv[0]);
return 1;
}
if (!strcmp(argv[1], "bench-single"))
bench_single();
else if (!strcmp(argv[1], "bench-multi"))
bench_multi();
else if (!strcmp(argv[1], "fill"))
fill();
else {
usage(argv[0]);
return 1;
}
return 0;
}
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