Link: https://lore.kernel.org/all/cover.1673539719.git.ydroneaud@xxxxxxxxxx/ Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx> --- tools/testing/crypto/getrandom/Makefile | 4 + .../testing/crypto/getrandom/test-getrandom.c | 307 ++++++++++++++++++ 2 files changed, 311 insertions(+) create mode 100644 tools/testing/crypto/getrandom/Makefile create mode 100644 tools/testing/crypto/getrandom/test-getrandom.c diff --git a/tools/testing/crypto/getrandom/Makefile b/tools/testing/crypto/getrandom/Makefile new file mode 100644 index 000000000000..1370b6f1ae94 --- /dev/null +++ b/tools/testing/crypto/getrandom/Makefile @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0+ + +test-getrandom: test-getrandom.c + $(CC) $(CPPFLAGS) $(CFLAGS) -I ../../../../usr/include/ -O2 -Wall -Wextra -o $@ $^ -ldl diff --git a/tools/testing/crypto/getrandom/test-getrandom.c b/tools/testing/crypto/getrandom/test-getrandom.c new file mode 100644 index 000000000000..311eef503f50 --- /dev/null +++ b/tools/testing/crypto/getrandom/test-getrandom.c @@ -0,0 +1,307 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2022 Yann Droneaud. All Rights Reserved. + */ + +#include <dlfcn.h> +#include <errno.h> +#include <inttypes.h> +#include <stdarg.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/syscall.h> +#include <time.h> +#include <unistd.h> + +#include <linux/random.h> + +static size_t pagesz; +static size_t discarded; + +typedef ssize_t(*getrandom_fn) (void *, size_t, int); + +static bool grnd_timestamp; +static getrandom_fn getrandom_vDSO; + +static ssize_t getrandom_syscall(void *buffer, size_t size, int flags) +{ + return syscall(SYS_getrandom, buffer, size, flags); +} + +static ssize_t timestamp(getrandom_fn _getrandom, uint64_t *grnd_ts, + size_t size) +{ + ssize_t ret; + + ret = _getrandom(grnd_ts, size, GRND_TIMESTAMP); + if (ret < 0) { + fprintf(stderr, + "getrandom(,,GRND_TIMESTAMP) failed: %ld (%s)\n", -ret, + strerror((int)-ret)); + return -1; + } + + return ret; +} + +static void fetch(getrandom_fn _getrandom, void *buffer, size_t size) +{ + ssize_t ret; + + ret = _getrandom(buffer, size, 0); + if (ret < 0) { + fprintf(stderr, "getrandom(,,0) failed: %ld (%s)\n", -ret, + strerror((int)-ret)); + exit(EXIT_FAILURE); + } +} + +struct rng { + uint64_t grnd_ts; + size_t availsz; /* available bytes in buffer */ + size_t buffersz; /* buffer size */ + uint8_t buffer[]; +}; + +static struct rng *rng; + +static void init_rng(void) +{ + int r; + ssize_t s; + void *p; + + r = getpagesize(); + if (r == -1) { + fprintf(stderr, "getpagesize() failed: %d\n", errno); + exit(EXIT_FAILURE); + } + + pagesz = (size_t)r; + + p = mmap(NULL, pagesz, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + if (p == MAP_FAILED) { + fprintf(stderr, "mmap() failed: %d\n", errno); + exit(EXIT_FAILURE); + } + + r = madvise(p, pagesz, MADV_DONTDUMP | MADV_WIPEONFORK); + if (r == -1) { + fprintf(stderr, "madvise() failed: %d\n", errno); + exit(EXIT_FAILURE); + } + + r = mlock(p, pagesz); + if (r == -1) + fprintf(stderr, "mlock() failed: %d\n", errno); + + rng = p; + + s = timestamp(getrandom_syscall, &rng->grnd_ts, sizeof(rng->grnd_ts)); + if (s == -1) + return; + + printf("getrandom() support GRND_TIMESTAMP\n"); + + grnd_timestamp = true; +} + +static void init_vdso(void) +{ + void *h; + void *p; + + h = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); + if (!h) { + fprintf(stderr, "failed to open vDSO: %s\n", dlerror()); + return; + } + + p = dlsym(h, "__vdso_getrandom"); + if (!p) { + fprintf(stderr, "getrandom() not found in vDSO: %s\n", + dlerror()); + return; + } + + printf("found getrandom() in vDSO at %p\n", p); + + getrandom_vDSO = p; +} + +/* + * 1) check timestamp isn't expired + * 2) if expired or there's not enough data in buffer + * a) if expired, reset buffer size, + * b) fetch new random stream + * c) check timestamp + * d) if expired, reset buffer size, go to b) + * + */ +static void ensure(getrandom_fn _getrandom, size_t request) +{ + ssize_t r; + + r = timestamp(_getrandom, &rng->grnd_ts, sizeof(rng->grnd_ts)); + switch (r) { + case 0: /* timestamp didn't change */ + /* enough available random bytes ? */ + if (rng->availsz >= request) + return; + + /* increase buffer size when drained */ + if (rng->buffersz < pagesz - sizeof(*rng)) + rng->buffersz *= 2; + + /* no less than 32 */ + if (rng->buffersz < 32) + rng->buffersz = 32; + + /* no more than a full page minus the rng structure */ + if (rng->buffersz > pagesz - sizeof(*rng)) + rng->buffersz = pagesz - sizeof(*rng); + + break; + + case sizeof(rng->grnd_ts): /* timestamp did change, random bytes must be discarded */ + rng->buffersz = 32; /* reset size */ + break; + + default: + fprintf(stderr, "unexpected timestamp size %zd\n", r); + exit(EXIT_FAILURE); + } + + /* keep fetching if timestamp is updated */ + for (;;) { + if (rng->availsz) + discarded += rng->availsz; + + fetch(_getrandom, rng->buffer, rng->buffersz); + rng->availsz = rng->buffersz; + + r = timestamp(_getrandom, &rng->grnd_ts, sizeof(rng->grnd_ts)); + + switch (r) { + case 0: /* timestamp didn't change between previous check and last fetch */ + return; + + case sizeof(rng->grnd_ts): /* timestamp did change, random bytes just fetched must be discarded */ + rng->buffersz = 32; /* reset size */ + continue; /* retry again */ + + default: + fprintf(stderr, "unexpected timestamp size %zd\n", r); + exit(EXIT_FAILURE); + } + } +} + +/* arc4random() */ +static void get_direct(getrandom_fn _getrandom) +{ + uint32_t v; + fetch(_getrandom, &v, sizeof(v)); +} + +static void get_pooled(getrandom_fn _getrandom) +{ + ensure(_getrandom, sizeof(uint32_t)); + rng->availsz -= sizeof(uint32_t); +} + +static inline struct timespec timespec_sub(const struct timespec *a, + const struct timespec *b) +{ + struct timespec res; + + res.tv_sec = a->tv_sec - b->tv_sec; + res.tv_nsec = a->tv_nsec - b->tv_nsec; + if (res.tv_nsec < 0) { + res.tv_sec--; + res.tv_nsec += 1000000000L; + } + + return res; +} + +#define SAMPLES 13 +#define VALUES (16 * 1024 * 1024) + +static void test_direct(getrandom_fn _getrandom, const char *method) +{ + struct timespec start, end, diff; + + for (int i = 0; i < SAMPLES; i++) { + clock_gettime(CLOCK_MONOTONIC, &start); + + for (uint32_t j = 0; j < VALUES; j++) + get_direct(_getrandom); + + clock_gettime(CLOCK_MONOTONIC, &end); + + diff = timespec_sub(&end, &start); + + printf("== direct %s getrandom(), %u u32, %lu.%09lu s, %.3f M u32/s, %.3f ns/u32\n", + method, VALUES, diff.tv_sec, diff.tv_nsec, + VALUES / (1000000 * + (diff.tv_sec + + (double)diff.tv_nsec / 1000000000UL)), + (double)(diff.tv_sec * 1000000000UL + + diff.tv_nsec) / VALUES); + } +} + +static void test_pooled(getrandom_fn _getrandom, const char *method) +{ + struct timespec start, end, diff; + + for (int i = 0; i < SAMPLES; i++) { + discarded = 0; + + clock_gettime(CLOCK_MONOTONIC, &start); + + for (uint32_t j = 0; j < VALUES; j++) + get_pooled(_getrandom); + + clock_gettime(CLOCK_MONOTONIC, &end); + + diff = timespec_sub(&end, &start); + + printf("== pooled %s getrandom(), %u u32, %lu.%09lu s, %.3f M u32/s, %.3f ns/u32, (%zu bytes discarded)\n", + method, VALUES, diff.tv_sec, diff.tv_nsec, + VALUES / (1000000 * + (diff.tv_sec + + (double)diff.tv_nsec / 1000000000UL)), + (double)(diff.tv_sec * 1000000000UL + + diff.tv_nsec) / VALUES, + discarded); + } +} + +int main(void) +{ + printf("getrandom(,,GRND_TIMESTAMP) test\n"); + + init_rng(); + init_vdso(); + + while (1) { + test_direct(getrandom_syscall, "syscall"); + + if (getrandom_vDSO) + test_direct(getrandom_vDSO, "vDSO"); + + if (grnd_timestamp) + test_pooled(getrandom_syscall, "syscall"); + + if (getrandom_vDSO && grnd_timestamp) + test_pooled(getrandom_vDSO, "vDSO"); + } + + return 0; +} -- 2.37.2
