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/*
* Strictly speaking, this is not a test. But it can report during test
* runs so relative performace can be measured.
*/
#define _GNU_SOURCE
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
#include <sys/param.h>
#include <sys/prctl.h>
#include <sys/syscall.h>
#include <sys/types.h>
#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
unsigned long long timing(clockid_t clk_id, unsigned long long samples)
{
struct timespec start, finish;
unsigned long long i;
pid_t pid, ret;
pid = getpid();
assert(clock_gettime(clk_id, &start) == 0);
for (i = 0; i < samples; i++) {
ret = syscall(__NR_getpid);
assert(pid == ret);
}
assert(clock_gettime(clk_id, &finish) == 0);
i = finish.tv_sec - start.tv_sec;
i *= 1000000000ULL;
i += finish.tv_nsec - start.tv_nsec;
printf("%lu.%09lu - %lu.%09lu = %llu (%.1fs)\n",
finish.tv_sec, finish.tv_nsec,
start.tv_sec, start.tv_nsec,
i, (double)i / 1000000000.0);
return i;
}
unsigned long long calibrate(void)
{
struct timespec start, finish;
unsigned long long i, samples, step = 9973;
pid_t pid, ret;
int seconds = 15;
printf("Calibrating sample size for %d seconds worth of syscalls ...\n", seconds);
samples = 0;
pid = getpid();
assert(clock_gettime(CLOCK_MONOTONIC, &start) == 0);
do {
for (i = 0; i < step; i++) {
ret = syscall(__NR_getpid);
assert(pid == ret);
}
assert(clock_gettime(CLOCK_MONOTONIC, &finish) == 0);
samples += step;
i = finish.tv_sec - start.tv_sec;
i *= 1000000000ULL;
i += finish.tv_nsec - start.tv_nsec;
} while (i < 1000000000ULL);
return samples * seconds;
}
bool approx(int i_one, int i_two)
{
double one = i_one, one_bump = one * 0.01;
double two = i_two, two_bump = two * 0.01;
one_bump = one + MAX(one_bump, 2.0);
two_bump = two + MAX(two_bump, 2.0);
/* Equal to, or within 1% or 2 digits */
if (one == two ||
(one > two && one <= two_bump) ||
(two > one && two <= one_bump))
return true;
return false;
}
bool le(int i_one, int i_two)
{
if (i_one <= i_two)
return true;
return false;
}
long compare(const char *name_one, const char *name_eval, const char *name_two,
unsigned long long one, bool (*eval)(int, int), unsigned long long two)
{
bool good;
printf("\t%s %s %s (%lld %s %lld): ", name_one, name_eval, name_two,
(long long)one, name_eval, (long long)two);
if (one > INT_MAX) {
printf("Miscalculation! Measurement went negative: %lld\n", (long long)one);
return 1;
}
if (two > INT_MAX) {
printf("Miscalculation! Measurement went negative: %lld\n", (long long)two);
return 1;
}
good = eval(one, two);
printf("%s\n", good ? "✔️" : "❌");
return good ? 0 : 1;
}
int main(int argc, char *argv[])
{
struct sock_filter bitmap_filter[] = {
BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, nr)),
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog bitmap_prog = {
.len = (unsigned short)ARRAY_SIZE(bitmap_filter),
.filter = bitmap_filter,
};
struct sock_filter filter[] = {
BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, args[0])),
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog prog = {
.len = (unsigned short)ARRAY_SIZE(filter),
.filter = filter,
};
long ret, bits;
unsigned long long samples, calc;
unsigned long long native, filter1, filter2, bitmap1, bitmap2;
unsigned long long entry, per_filter1, per_filter2;
setbuf(stdout, NULL);
printf("Running on:\n");
system("uname -a");
printf("Current BPF sysctl settings:\n");
/* Avoid using "sysctl" which may not be installed. */
system("grep -H . /proc/sys/net/core/bpf_jit_enable");
system("grep -H . /proc/sys/net/core/bpf_jit_harden");
if (argc > 1)
samples = strtoull(argv[1], NULL, 0);
else
samples = calibrate();
printf("Benchmarking %llu syscalls...\n", samples);
/* Native call */
native = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
printf("getpid native: %llu ns\n", native);
ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
assert(ret == 0);
/* One filter resulting in a bitmap */
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
assert(ret == 0);
bitmap1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
printf("getpid RET_ALLOW 1 filter (bitmap): %llu ns\n", bitmap1);
/* Second filter resulting in a bitmap */
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
assert(ret == 0);
bitmap2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
printf("getpid RET_ALLOW 2 filters (bitmap): %llu ns\n", bitmap2);
/* Third filter, can no longer be converted to bitmap */
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
assert(ret == 0);
filter1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
printf("getpid RET_ALLOW 3 filters (full): %llu ns\n", filter1);
/* Fourth filter, can not be converted to bitmap because of filter 3 */
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
assert(ret == 0);
filter2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
printf("getpid RET_ALLOW 4 filters (full): %llu ns\n", filter2);
/* Estimations */
#define ESTIMATE(fmt, var, what) do { \
var = (what); \
printf("Estimated " fmt ": %llu ns\n", var); \
if (var > INT_MAX) \
goto more_samples; \
} while (0)
ESTIMATE("total seccomp overhead for 1 bitmapped filter", calc,
bitmap1 - native);
ESTIMATE("total seccomp overhead for 2 bitmapped filters", calc,
bitmap2 - native);
ESTIMATE("total seccomp overhead for 3 full filters", calc,
filter1 - native);
ESTIMATE("total seccomp overhead for 4 full filters", calc,
filter2 - native);
ESTIMATE("seccomp entry overhead", entry,
bitmap1 - native - (bitmap2 - bitmap1));
ESTIMATE("seccomp per-filter overhead (last 2 diff)", per_filter1,
filter2 - filter1);
ESTIMATE("seccomp per-filter overhead (filters / 4)", per_filter2,
(filter2 - native - entry) / 4);
printf("Expectations:\n");
ret |= compare("native", "≤", "1 bitmap", native, le, bitmap1);
bits = compare("native", "≤", "1 filter", native, le, filter1);
if (bits)
goto more_samples;
ret |= compare("per-filter (last 2 diff)", "≈", "per-filter (filters / 4)",
per_filter1, approx, per_filter2);
bits = compare("1 bitmapped", "≈", "2 bitmapped",
bitmap1 - native, approx, bitmap2 - native);
if (bits) {
printf("Skipping constant action bitmap expectations: they appear unsupported.\n");
goto out;
}
ret |= compare("entry", "≈", "1 bitmapped", entry, approx, bitmap1 - native);
ret |= compare("entry", "≈", "2 bitmapped", entry, approx, bitmap2 - native);
ret |= compare("native + entry + (per filter * 4)", "≈", "4 filters total",
entry + (per_filter1 * 4) + native, approx, filter2);
if (ret == 0)
goto out;
more_samples:
printf("Saw unexpected benchmark result. Try running again with more samples?\n");
out:
return 0;
}
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