1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * It is possible to use SO_REUSEPORT to open multiple sockets bound to 4 * equivalent local addresses using AF_INET and AF_INET6 at the same time. If 5 * the AF_INET6 socket has IPV6_V6ONLY set, it's clear which socket should 6 * receive a given incoming packet. However, when it is not set, incoming v4 7 * packets should prefer the AF_INET socket(s). This behavior was defined with 8 * the original SO_REUSEPORT implementation, but broke with 9 * e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection") 10 * This test creates these mixed AF_INET/AF_INET6 sockets and asserts the 11 * AF_INET preference for v4 packets. 12 */ 13 14 #define _GNU_SOURCE 15 16 #include <arpa/inet.h> 17 #include <errno.h> 18 #include <error.h> 19 #include <linux/in.h> 20 #include <linux/unistd.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include <sys/epoll.h> 25 #include <sys/types.h> 26 #include <sys/socket.h> 27 #include <unistd.h> 28 #include <sched.h> 29 30 static const int PORT = 8888; 31 32 static void build_rcv_fd(int family, int proto, int *rcv_fds, int count) 33 { 34 struct sockaddr_storage addr; 35 struct sockaddr_in *addr4; 36 struct sockaddr_in6 *addr6; 37 int opt, i; 38 39 switch (family) { 40 case AF_INET: 41 addr4 = (struct sockaddr_in *)&addr; 42 addr4->sin_family = AF_INET; 43 addr4->sin_addr.s_addr = htonl(INADDR_ANY); 44 addr4->sin_port = htons(PORT); 45 break; 46 case AF_INET6: 47 addr6 = (struct sockaddr_in6 *)&addr; 48 addr6->sin6_family = AF_INET6; 49 addr6->sin6_addr = in6addr_any; 50 addr6->sin6_port = htons(PORT); 51 break; 52 default: 53 error(1, 0, "Unsupported family %d", family); 54 } 55 56 for (i = 0; i < count; ++i) { 57 rcv_fds[i] = socket(family, proto, 0); 58 if (rcv_fds[i] < 0) 59 error(1, errno, "failed to create receive socket"); 60 61 opt = 1; 62 if (setsockopt(rcv_fds[i], SOL_SOCKET, SO_REUSEPORT, &opt, 63 sizeof(opt))) 64 error(1, errno, "failed to set SO_REUSEPORT"); 65 66 if (bind(rcv_fds[i], (struct sockaddr *)&addr, sizeof(addr))) 67 error(1, errno, "failed to bind receive socket"); 68 69 if (proto == SOCK_STREAM && listen(rcv_fds[i], 10)) 70 error(1, errno, "failed to listen on receive port"); 71 } 72 } 73 74 static void send_from_v4(int proto) 75 { 76 struct sockaddr_in saddr, daddr; 77 int fd; 78 79 saddr.sin_family = AF_INET; 80 saddr.sin_addr.s_addr = htonl(INADDR_ANY); 81 saddr.sin_port = 0; 82 83 daddr.sin_family = AF_INET; 84 daddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); 85 daddr.sin_port = htons(PORT); 86 87 fd = socket(AF_INET, proto, 0); 88 if (fd < 0) 89 error(1, errno, "failed to create send socket"); 90 91 if (bind(fd, (struct sockaddr *)&saddr, sizeof(saddr))) 92 error(1, errno, "failed to bind send socket"); 93 94 if (connect(fd, (struct sockaddr *)&daddr, sizeof(daddr))) 95 error(1, errno, "failed to connect send socket"); 96 97 if (send(fd, "a", 1, 0) < 0) 98 error(1, errno, "failed to send message"); 99 100 close(fd); 101 } 102 103 static int receive_once(int epfd, int proto) 104 { 105 struct epoll_event ev; 106 int i, fd; 107 char buf[8]; 108 109 i = epoll_wait(epfd, &ev, 1, -1); 110 if (i < 0) 111 error(1, errno, "epoll_wait failed"); 112 113 if (proto == SOCK_STREAM) { 114 fd = accept(ev.data.fd, NULL, NULL); 115 if (fd < 0) 116 error(1, errno, "failed to accept"); 117 i = recv(fd, buf, sizeof(buf), 0); 118 close(fd); 119 } else { 120 i = recv(ev.data.fd, buf, sizeof(buf), 0); 121 } 122 123 if (i < 0) 124 error(1, errno, "failed to recv"); 125 126 return ev.data.fd; 127 } 128 129 static void test(int *rcv_fds, int count, int proto) 130 { 131 struct epoll_event ev; 132 int epfd, i, test_fd; 133 int test_family; 134 socklen_t len; 135 136 epfd = epoll_create(1); 137 if (epfd < 0) 138 error(1, errno, "failed to create epoll"); 139 140 ev.events = EPOLLIN; 141 for (i = 0; i < count; ++i) { 142 ev.data.fd = rcv_fds[i]; 143 if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fds[i], &ev)) 144 error(1, errno, "failed to register sock epoll"); 145 } 146 147 send_from_v4(proto); 148 149 test_fd = receive_once(epfd, proto); 150 len = sizeof(test_family); 151 if (getsockopt(test_fd, SOL_SOCKET, SO_DOMAIN, &test_family, &len)) 152 error(1, errno, "failed to read socket domain"); 153 if (test_family != AF_INET) 154 error(1, 0, "expected to receive on v4 socket but got v6 (%d)", 155 test_family); 156 157 close(epfd); 158 } 159 160 static void setup_netns(void) 161 { 162 if (unshare(CLONE_NEWNET)) 163 error(1, errno, "failed to unshare netns"); 164 if (system("ip link set lo up")) 165 error(1, 0, "failed to bring up lo interface in netns"); 166 } 167 168 int main(void) 169 { 170 int rcv_fds[32], i; 171 172 setup_netns(); 173 174 fprintf(stderr, "---- UDP IPv4 created before IPv6 ----\n"); 175 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 5); 176 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[5]), 5); 177 test(rcv_fds, 10, SOCK_DGRAM); 178 for (i = 0; i < 10; ++i) 179 close(rcv_fds[i]); 180 181 fprintf(stderr, "---- UDP IPv6 created before IPv4 ----\n"); 182 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 5); 183 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[5]), 5); 184 test(rcv_fds, 10, SOCK_DGRAM); 185 for (i = 0; i < 10; ++i) 186 close(rcv_fds[i]); 187 188 /* NOTE: UDP socket lookups traverse a different code path when there 189 * are > 10 sockets in a group. 190 */ 191 fprintf(stderr, "---- UDP IPv4 created before IPv6 (large) ----\n"); 192 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 16); 193 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[16]), 16); 194 test(rcv_fds, 32, SOCK_DGRAM); 195 for (i = 0; i < 32; ++i) 196 close(rcv_fds[i]); 197 198 fprintf(stderr, "---- UDP IPv6 created before IPv4 (large) ----\n"); 199 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 16); 200 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[16]), 16); 201 test(rcv_fds, 32, SOCK_DGRAM); 202 for (i = 0; i < 32; ++i) 203 close(rcv_fds[i]); 204 205 fprintf(stderr, "---- TCP IPv4 created before IPv6 ----\n"); 206 build_rcv_fd(AF_INET, SOCK_STREAM, rcv_fds, 5); 207 build_rcv_fd(AF_INET6, SOCK_STREAM, &(rcv_fds[5]), 5); 208 test(rcv_fds, 10, SOCK_STREAM); 209 for (i = 0; i < 10; ++i) 210 close(rcv_fds[i]); 211 212 fprintf(stderr, "---- TCP IPv6 created before IPv4 ----\n"); 213 build_rcv_fd(AF_INET6, SOCK_STREAM, rcv_fds, 5); 214 build_rcv_fd(AF_INET, SOCK_STREAM, &(rcv_fds[5]), 5); 215 test(rcv_fds, 10, SOCK_STREAM); 216 for (i = 0; i < 10; ++i) 217 close(rcv_fds[i]); 218 219 fprintf(stderr, "SUCCESS\n"); 220 return 0; 221 } 222