1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Test functionality of BPF filters with SO_REUSEPORT. This program creates
4 * an SO_REUSEPORT receiver group containing one socket per CPU core. It then
5 * creates a BPF program that will select a socket from this group based
6 * on the core id that receives the packet. The sending code artificially
7 * moves itself to run on different core ids and sends one message from
8 * each core. Since these packets are delivered over loopback, they should
9 * arrive on the same core that sent them. The receiving code then ensures
10 * that the packet was received on the socket for the corresponding core id.
11 * This entire process is done for several different core id permutations
12 * and for each IPv4/IPv6 and TCP/UDP combination.
13 */
14
15 #define _GNU_SOURCE
16
17 #include <arpa/inet.h>
18 #include <errno.h>
19 #include <error.h>
20 #include <linux/filter.h>
21 #include <linux/in.h>
22 #include <linux/unistd.h>
23 #include <sched.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <sys/epoll.h>
28 #include <sys/types.h>
29 #include <sys/socket.h>
30 #include <unistd.h>
31
32 static const int PORT = 8888;
33
34 static void build_rcv_group(int *rcv_fd, size_t len, int family, int proto)
35 {
36 struct sockaddr_storage addr;
37 struct sockaddr_in *addr4;
38 struct sockaddr_in6 *addr6;
39 size_t i;
40 int opt;
41
42 switch (family) {
43 case AF_INET:
44 addr4 = (struct sockaddr_in *)&addr;
45 addr4->sin_family = AF_INET;
46 addr4->sin_addr.s_addr = htonl(INADDR_ANY);
47 addr4->sin_port = htons(PORT);
48 break;
49 case AF_INET6:
50 addr6 = (struct sockaddr_in6 *)&addr;
51 addr6->sin6_family = AF_INET6;
52 addr6->sin6_addr = in6addr_any;
53 addr6->sin6_port = htons(PORT);
54 break;
55 default:
56 error(1, 0, "Unsupported family %d", family);
57 }
58
59 for (i = 0; i < len; ++i) {
60 rcv_fd[i] = socket(family, proto, 0);
61 if (rcv_fd[i] < 0)
62 error(1, errno, "failed to create receive socket");
63
64 opt = 1;
65 if (setsockopt(rcv_fd[i], SOL_SOCKET, SO_REUSEPORT, &opt,
66 sizeof(opt)))
67 error(1, errno, "failed to set SO_REUSEPORT");
68
69 if (bind(rcv_fd[i], (struct sockaddr *)&addr, sizeof(addr)))
70 error(1, errno, "failed to bind receive socket");
71
72 if (proto == SOCK_STREAM && listen(rcv_fd[i], len * 10))
73 error(1, errno, "failed to listen on receive port");
74 }
75 }
76
77 static void attach_bpf(int fd)
78 {
79 struct sock_filter code[] = {
80 /* A = raw_smp_processor_id() */
81 { BPF_LD | BPF_W | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_CPU },
82 /* return A */
83 { BPF_RET | BPF_A, 0, 0, 0 },
84 };
85 struct sock_fprog p = {
86 .len = 2,
87 .filter = code,
88 };
89
90 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, &p, sizeof(p)))
91 error(1, errno, "failed to set SO_ATTACH_REUSEPORT_CBPF");
92 }
93
94 static void send_from_cpu(int cpu_id, int family, int proto)
95 {
96 struct sockaddr_storage saddr, daddr;
97 struct sockaddr_in *saddr4, *daddr4;
98 struct sockaddr_in6 *saddr6, *daddr6;
99 cpu_set_t cpu_set;
100 int fd;
101
102 switch (family) {
103 case AF_INET:
104 saddr4 = (struct sockaddr_in *)&saddr;
105 saddr4->sin_family = AF_INET;
106 saddr4->sin_addr.s_addr = htonl(INADDR_ANY);
107 saddr4->sin_port = 0;
108
109 daddr4 = (struct sockaddr_in *)&daddr;
110 daddr4->sin_family = AF_INET;
111 daddr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
112 daddr4->sin_port = htons(PORT);
113 break;
114 case AF_INET6:
115 saddr6 = (struct sockaddr_in6 *)&saddr;
116 saddr6->sin6_family = AF_INET6;
117 saddr6->sin6_addr = in6addr_any;
118 saddr6->sin6_port = 0;
119
120 daddr6 = (struct sockaddr_in6 *)&daddr;
121 daddr6->sin6_family = AF_INET6;
122 daddr6->sin6_addr = in6addr_loopback;
123 daddr6->sin6_port = htons(PORT);
124 break;
125 default:
126 error(1, 0, "Unsupported family %d", family);
127 }
128
129 memset(&cpu_set, 0, sizeof(cpu_set));
130 CPU_SET(cpu_id, &cpu_set);
131 if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0)
132 error(1, errno, "failed to pin to cpu");
133
134 fd = socket(family, proto, 0);
135 if (fd < 0)
136 error(1, errno, "failed to create send socket");
137
138 if (bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)))
139 error(1, errno, "failed to bind send socket");
140
141 if (connect(fd, (struct sockaddr *)&daddr, sizeof(daddr)))
142 error(1, errno, "failed to connect send socket");
143
144 if (send(fd, "a", 1, 0) < 0)
145 error(1, errno, "failed to send message");
146
147 close(fd);
148 }
149
150 static
151 void receive_on_cpu(int *rcv_fd, int len, int epfd, int cpu_id, int proto)
152 {
153 struct epoll_event ev;
154 int i, fd;
155 char buf[8];
156
157 i = epoll_wait(epfd, &ev, 1, -1);
158 if (i < 0)
159 error(1, errno, "epoll_wait failed");
160
161 if (proto == SOCK_STREAM) {
162 fd = accept(ev.data.fd, NULL, NULL);
163 if (fd < 0)
164 error(1, errno, "failed to accept");
165 i = recv(fd, buf, sizeof(buf), 0);
166 close(fd);
167 } else {
168 i = recv(ev.data.fd, buf, sizeof(buf), 0);
169 }
170
171 if (i < 0)
172 error(1, errno, "failed to recv");
173
174 for (i = 0; i < len; ++i)
175 if (ev.data.fd == rcv_fd[i])
176 break;
177 if (i == len)
178 error(1, 0, "failed to find socket");
179 fprintf(stderr, "send cpu %d, receive socket %d\n", cpu_id, i);
180 if (cpu_id != i)
181 error(1, 0, "cpu id/receive socket mismatch");
182 }
183
184 static void test(int *rcv_fd, int len, int family, int proto)
185 {
186 struct epoll_event ev;
187 int epfd, cpu;
188
189 build_rcv_group(rcv_fd, len, family, proto);
190 attach_bpf(rcv_fd[0]);
191
192 epfd = epoll_create(1);
193 if (epfd < 0)
194 error(1, errno, "failed to create epoll");
195 for (cpu = 0; cpu < len; ++cpu) {
196 ev.events = EPOLLIN;
197 ev.data.fd = rcv_fd[cpu];
198 if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fd[cpu], &ev))
199 error(1, errno, "failed to register sock epoll");
200 }
201
202 /* Forward iterate */
203 for (cpu = 0; cpu < len; ++cpu) {
204 send_from_cpu(cpu, family, proto);
205 receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
206 }
207
208 /* Reverse iterate */
209 for (cpu = len - 1; cpu >= 0; --cpu) {
210 send_from_cpu(cpu, family, proto);
211 receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
212 }
213
214 /* Even cores */
215 for (cpu = 0; cpu < len; cpu += 2) {
216 send_from_cpu(cpu, family, proto);
217 receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
218 }
219
220 /* Odd cores */
221 for (cpu = 1; cpu < len; cpu += 2) {
222 send_from_cpu(cpu, family, proto);
223 receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
224 }
225
226 close(epfd);
227 for (cpu = 0; cpu < len; ++cpu)
228 close(rcv_fd[cpu]);
229 }
230
231 int main(void)
232 {
233 int *rcv_fd, cpus;
234
235 cpus = sysconf(_SC_NPROCESSORS_ONLN);
236 if (cpus <= 0)
237 error(1, errno, "failed counting cpus");
238
239 rcv_fd = calloc(cpus, sizeof(int));
240 if (!rcv_fd)
241 error(1, 0, "failed to allocate array");
242
243 fprintf(stderr, "---- IPv4 UDP ----\n");
244 test(rcv_fd, cpus, AF_INET, SOCK_DGRAM);
245
246 fprintf(stderr, "---- IPv6 UDP ----\n");
247 test(rcv_fd, cpus, AF_INET6, SOCK_DGRAM);
248
249 fprintf(stderr, "---- IPv4 TCP ----\n");
250 test(rcv_fd, cpus, AF_INET, SOCK_STREAM);
251
252 fprintf(stderr, "---- IPv6 TCP ----\n");
253 test(rcv_fd, cpus, AF_INET6, SOCK_STREAM);
254
255 free(rcv_fd);
256
257 fprintf(stderr, "SUCCESS\n");
258 return 0;
259 }
260
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