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 
timing(clockid_t clk_id,unsigned long long samples)23 unsigned 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 
calibrate(void)49 unsigned 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 
approx(int i_one,int i_two)77 bool 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 
le(int i_one,int i_two)93 bool le(int i_one, int i_two)
94 {
95 	if (i_one <= i_two)
96 		return true;
97 	return false;
98 }
99 
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)100 long 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 
main(int argc,char * argv[])122 int 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 
244 more_samples:
245 	printf("Saw unexpected benchmark result. Try running again with more samples?\n");
246 out:
247 	return 0;
248 }
249