1 /*
2 * Strictly speaking, this is not a test. But it can report during test
3 * runs so relative performace can be measured.
4 */
5 #define _GNU_SOURCE
6 #include <assert.h>
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <time.h>
10 #include <unistd.h>
11 #include <linux/filter.h>
12 #include <linux/seccomp.h>
13 #include <sys/prctl.h>
14 #include <sys/syscall.h>
15 #include <sys/types.h>
16
17 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
18
timing(clockid_t clk_id,unsigned long long samples)19 unsigned long long timing(clockid_t clk_id, unsigned long long samples)
20 {
21 struct timespec start, finish;
22 unsigned long long i;
23 pid_t pid, ret;
24
25 pid = getpid();
26 assert(clock_gettime(clk_id, &start) == 0);
27 for (i = 0; i < samples; i++) {
28 ret = syscall(__NR_getpid);
29 assert(pid == ret);
30 }
31 assert(clock_gettime(clk_id, &finish) == 0);
32
33 i = finish.tv_sec - start.tv_sec;
34 i *= 1000000000ULL;
35 i += finish.tv_nsec - start.tv_nsec;
36
37 printf("%lu.%09lu - %lu.%09lu = %llu (%.1fs)\n",
38 finish.tv_sec, finish.tv_nsec,
39 start.tv_sec, start.tv_nsec,
40 i, (double)i / 1000000000.0);
41
42 return i;
43 }
44
calibrate(void)45 unsigned long long calibrate(void)
46 {
47 struct timespec start, finish;
48 unsigned long long i, samples, step = 9973;
49 pid_t pid, ret;
50 int seconds = 15;
51
52 printf("Calibrating sample size for %d seconds worth of syscalls ...\n", seconds);
53
54 samples = 0;
55 pid = getpid();
56 assert(clock_gettime(CLOCK_MONOTONIC, &start) == 0);
57 do {
58 for (i = 0; i < step; i++) {
59 ret = syscall(__NR_getpid);
60 assert(pid == ret);
61 }
62 assert(clock_gettime(CLOCK_MONOTONIC, &finish) == 0);
63
64 samples += step;
65 i = finish.tv_sec - start.tv_sec;
66 i *= 1000000000ULL;
67 i += finish.tv_nsec - start.tv_nsec;
68 } while (i < 1000000000ULL);
69
70 return samples * seconds;
71 }
72
main(int argc,char * argv[])73 int main(int argc, char *argv[])
74 {
75 struct sock_filter filter[] = {
76 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
77 };
78 struct sock_fprog prog = {
79 .len = (unsigned short)ARRAY_SIZE(filter),
80 .filter = filter,
81 };
82 long ret;
83 unsigned long long samples;
84 unsigned long long native, filter1, filter2;
85
86 printf("Current BPF sysctl settings:\n");
87 system("sysctl net.core.bpf_jit_enable");
88 system("sysctl net.core.bpf_jit_harden");
89
90 if (argc > 1)
91 samples = strtoull(argv[1], NULL, 0);
92 else
93 samples = calibrate();
94
95 printf("Benchmarking %llu syscalls...\n", samples);
96
97 /* Native call */
98 native = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
99 printf("getpid native: %llu ns\n", native);
100
101 ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
102 assert(ret == 0);
103
104 /* One filter */
105 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
106 assert(ret == 0);
107
108 filter1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
109 printf("getpid RET_ALLOW 1 filter: %llu ns\n", filter1);
110
111 if (filter1 == native)
112 printf("No overhead measured!? Try running again with more samples.\n");
113
114 /* Two filters */
115 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
116 assert(ret == 0);
117
118 filter2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
119 printf("getpid RET_ALLOW 2 filters: %llu ns\n", filter2);
120
121 /* Calculations */
122 printf("Estimated total seccomp overhead for 1 filter: %llu ns\n",
123 filter1 - native);
124
125 printf("Estimated total seccomp overhead for 2 filters: %llu ns\n",
126 filter2 - native);
127
128 printf("Estimated seccomp per-filter overhead: %llu ns\n",
129 filter2 - filter1);
130
131 printf("Estimated seccomp entry overhead: %llu ns\n",
132 filter1 - native - (filter2 - filter1));
133
134 return 0;
135 }
136