@@ -4,12 +4,16 @@
*/
#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>
@@ -70,18 +74,74 @@ unsigned long long calibrate(void)
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;
- unsigned long long samples;
- unsigned long long native, filter1, filter2;
+
+ long ret, bits;
+ unsigned long long samples, calc;
+ unsigned long long native, filter1, filter2, bitmap1, bitmap2;
+ unsigned long long entry, per_filter1, per_filter2;
printf("Current BPF sysctl settings:\n");
system("sysctl net.core.bpf_jit_enable");
@@ -101,35 +161,82 @@ int main(int argc, char *argv[])
ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
assert(ret == 0);
- /* One filter */
- ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
+ /* One filter resulting in a bitmap */
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
assert(ret == 0);
- filter1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
- printf("getpid RET_ALLOW 1 filter: %llu ns\n", filter1);
+ 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);
- if (filter1 == native)
- printf("No overhead measured!? Try running again with more samples.\n");
+ bitmap2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
+ printf("getpid RET_ALLOW 2 filters (bitmap): %llu ns\n", bitmap2);
- /* Two filters */
+ /* Third filter, can no longer be converted to bitmap */
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
assert(ret == 0);
- filter2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
- printf("getpid RET_ALLOW 2 filters: %llu ns\n", filter2);
-
- /* Calculations */
- printf("Estimated total seccomp overhead for 1 filter: %llu ns\n",
- filter1 - native);
+ filter1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
+ printf("getpid RET_ALLOW 3 filters (full): %llu ns\n", filter1);
- printf("Estimated total seccomp overhead for 2 filters: %llu ns\n",
- filter2 - native);
+ /* 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);
- printf("Estimated seccomp per-filter overhead: %llu ns\n",
- filter2 - filter1);
+ 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;
+ }
- printf("Estimated seccomp entry overhead: %llu ns\n",
- filter1 - native - (filter2 - filter1));
+ 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;
}
@@ -1 +1 @@
-timeout=90
+timeout=120