1
2
3
4
5#define _GNU_SOURCE
6#include <assert.h>
7#include <limits.h>
8#include <stdbool.h>
9#include <stddef.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <time.h>
13#include <unistd.h>
14#include <linux/filter.h>
15#include <linux/seccomp.h>
16#include <sys/param.h>
17#include <sys/prctl.h>
18#include <sys/syscall.h>
19#include <sys/types.h>
20
21#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
22
23unsigned long long timing(clockid_t clk_id, unsigned long long samples)
24{
25 struct timespec start, finish;
26 unsigned long long i;
27 pid_t pid, ret;
28
29 pid = getpid();
30 assert(clock_gettime(clk_id, &start) == 0);
31 for (i = 0; i < samples; i++) {
32 ret = syscall(__NR_getpid);
33 assert(pid == ret);
34 }
35 assert(clock_gettime(clk_id, &finish) == 0);
36
37 i = finish.tv_sec - start.tv_sec;
38 i *= 1000000000ULL;
39 i += finish.tv_nsec - start.tv_nsec;
40
41 printf("%lu.%09lu - %lu.%09lu = %llu (%.1fs)\n",
42 finish.tv_sec, finish.tv_nsec,
43 start.tv_sec, start.tv_nsec,
44 i, (double)i / 1000000000.0);
45
46 return i;
47}
48
49unsigned long long calibrate(void)
50{
51 struct timespec start, finish;
52 unsigned long long i, samples, step = 9973;
53 pid_t pid, ret;
54 int seconds = 15;
55
56 printf("Calibrating sample size for %d seconds worth of syscalls ...\n", seconds);
57
58 samples = 0;
59 pid = getpid();
60 assert(clock_gettime(CLOCK_MONOTONIC, &start) == 0);
61 do {
62 for (i = 0; i < step; i++) {
63 ret = syscall(__NR_getpid);
64 assert(pid == ret);
65 }
66 assert(clock_gettime(CLOCK_MONOTONIC, &finish) == 0);
67
68 samples += step;
69 i = finish.tv_sec - start.tv_sec;
70 i *= 1000000000ULL;
71 i += finish.tv_nsec - start.tv_nsec;
72 } while (i < 1000000000ULL);
73
74 return samples * seconds;
75}
76
77bool approx(int i_one, int i_two)
78{
79 double one = i_one, one_bump = one * 0.01;
80 double two = i_two, two_bump = two * 0.01;
81
82 one_bump = one + MAX(one_bump, 2.0);
83 two_bump = two + MAX(two_bump, 2.0);
84
85
86 if (one == two ||
87 (one > two && one <= two_bump) ||
88 (two > one && two <= one_bump))
89 return true;
90 return false;
91}
92
93bool le(int i_one, int i_two)
94{
95 if (i_one <= i_two)
96 return true;
97 return false;
98}
99
100long compare(const char *name_one, const char *name_eval, const char *name_two,
101 unsigned long long one, bool (*eval)(int, int), unsigned long long two)
102{
103 bool good;
104
105 printf("\t%s %s %s (%lld %s %lld): ", name_one, name_eval, name_two,
106 (long long)one, name_eval, (long long)two);
107 if (one > INT_MAX) {
108 printf("Miscalculation! Measurement went negative: %lld\n", (long long)one);
109 return 1;
110 }
111 if (two > INT_MAX) {
112 printf("Miscalculation! Measurement went negative: %lld\n", (long long)two);
113 return 1;
114 }
115
116 good = eval(one, two);
117 printf("%s\n", good ? "✔️" : "❌");
118
119 return good ? 0 : 1;
120}
121
122int main(int argc, char *argv[])
123{
124 struct sock_filter bitmap_filter[] = {
125 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, nr)),
126 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
127 };
128 struct sock_fprog bitmap_prog = {
129 .len = (unsigned short)ARRAY_SIZE(bitmap_filter),
130 .filter = bitmap_filter,
131 };
132 struct sock_filter filter[] = {
133 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, args[0])),
134 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
135 };
136 struct sock_fprog prog = {
137 .len = (unsigned short)ARRAY_SIZE(filter),
138 .filter = filter,
139 };
140
141 long ret, bits;
142 unsigned long long samples, calc;
143 unsigned long long native, filter1, filter2, bitmap1, bitmap2;
144 unsigned long long entry, per_filter1, per_filter2;
145
146 setbuf(stdout, NULL);
147
148 printf("Running on:\n");
149 system("uname -a");
150
151 printf("Current BPF sysctl settings:\n");
152
153 system("grep -H . /proc/sys/net/core/bpf_jit_enable");
154 system("grep -H . /proc/sys/net/core/bpf_jit_harden");
155
156 if (argc > 1)
157 samples = strtoull(argv[1], NULL, 0);
158 else
159 samples = calibrate();
160
161 printf("Benchmarking %llu syscalls...\n", samples);
162
163
164 native = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
165 printf("getpid native: %llu ns\n", native);
166
167 ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
168 assert(ret == 0);
169
170
171 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
172 assert(ret == 0);
173
174 bitmap1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
175 printf("getpid RET_ALLOW 1 filter (bitmap): %llu ns\n", bitmap1);
176
177
178 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
179 assert(ret == 0);
180
181 bitmap2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
182 printf("getpid RET_ALLOW 2 filters (bitmap): %llu ns\n", bitmap2);
183
184
185 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
186 assert(ret == 0);
187
188 filter1 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
189 printf("getpid RET_ALLOW 3 filters (full): %llu ns\n", filter1);
190
191
192 ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &bitmap_prog);
193 assert(ret == 0);
194
195 filter2 = timing(CLOCK_PROCESS_CPUTIME_ID, samples) / samples;
196 printf("getpid RET_ALLOW 4 filters (full): %llu ns\n", filter2);
197
198
199#define ESTIMATE(fmt, var, what) do { \
200 var = (what); \
201 printf("Estimated " fmt ": %llu ns\n", var); \
202 if (var > INT_MAX) \
203 goto more_samples; \
204 } while (0)
205
206 ESTIMATE("total seccomp overhead for 1 bitmapped filter", calc,
207 bitmap1 - native);
208 ESTIMATE("total seccomp overhead for 2 bitmapped filters", calc,
209 bitmap2 - native);
210 ESTIMATE("total seccomp overhead for 3 full filters", calc,
211 filter1 - native);
212 ESTIMATE("total seccomp overhead for 4 full filters", calc,
213 filter2 - native);
214 ESTIMATE("seccomp entry overhead", entry,
215 bitmap1 - native - (bitmap2 - bitmap1));
216 ESTIMATE("seccomp per-filter overhead (last 2 diff)", per_filter1,
217 filter2 - filter1);
218 ESTIMATE("seccomp per-filter overhead (filters / 4)", per_filter2,
219 (filter2 - native - entry) / 4);
220
221 printf("Expectations:\n");
222 ret |= compare("native", "≤", "1 bitmap", native, le, bitmap1);
223 bits = compare("native", "≤", "1 filter", native, le, filter1);
224 if (bits)
225 goto more_samples;
226
227 ret |= compare("per-filter (last 2 diff)", "≈", "per-filter (filters / 4)",
228 per_filter1, approx, per_filter2);
229
230 bits = compare("1 bitmapped", "≈", "2 bitmapped",
231 bitmap1 - native, approx, bitmap2 - native);
232 if (bits) {
233 printf("Skipping constant action bitmap expectations: they appear unsupported.\n");
234 goto out;
235 }
236
237 ret |= compare("entry", "≈", "1 bitmapped", entry, approx, bitmap1 - native);
238 ret |= compare("entry", "≈", "2 bitmapped", entry, approx, bitmap2 - native);
239 ret |= compare("native + entry + (per filter * 4)", "≈", "4 filters total",
240 entry + (per_filter1 * 4) + native, approx, filter2);
241 if (ret == 0)
242 goto out;
243
244more_samples:
245 printf("Saw unexpected benchmark result. Try running again with more samples?\n");
246out:
247 return 0;
248}
249
