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 <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#include "../kselftest.h"
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	/* Equal to, or within 1% or 2 digits */
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	/* Avoid using "sysctl" which may not be installed. */
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	/* Native call */
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	/* One filter resulting in a bitmap */
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	/* Second filter resulting in a bitmap */
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	/* Third filter, can no longer be converted to bitmap */
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	/* Fourth filter, can not be converted to bitmap because of filter 3 */
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	/* Estimations */
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