1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Check if we can fully utilize 4-tuples for connect(). 4 * 5 * Rules to bind sockets to the same port when all ephemeral ports are 6 * exhausted. 7 * 8 * 1. if there are TCP_LISTEN sockets on the port, fail to bind. 9 * 2. if there are sockets without SO_REUSEADDR, fail to bind. 10 * 3. if SO_REUSEADDR is disabled, fail to bind. 11 * 4. if SO_REUSEADDR is enabled and SO_REUSEPORT is disabled, 12 * succeed to bind. 13 * 5. if SO_REUSEADDR and SO_REUSEPORT are enabled and 14 * there is no socket having the both options and the same EUID, 15 * succeed to bind. 16 * 6. fail to bind. 17 * 18 * Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp> 19 */ 20 #include <arpa/inet.h> 21 #include <netinet/in.h> 22 #include <sys/socket.h> 23 #include <sys/types.h> 24 #include <unistd.h> 25 #include "../kselftest_harness.h" 26 27 struct reuse_opts { 28 int reuseaddr[2]; 29 int reuseport[2]; 30 }; 31 32 struct reuse_opts unreusable_opts[12] = { 33 {{0, 0}, {0, 0}}, 34 {{0, 0}, {0, 1}}, 35 {{0, 0}, {1, 0}}, 36 {{0, 0}, {1, 1}}, 37 {{0, 1}, {0, 0}}, 38 {{0, 1}, {0, 1}}, 39 {{0, 1}, {1, 0}}, 40 {{0, 1}, {1, 1}}, 41 {{1, 0}, {0, 0}}, 42 {{1, 0}, {0, 1}}, 43 {{1, 0}, {1, 0}}, 44 {{1, 0}, {1, 1}}, 45 }; 46 47 struct reuse_opts reusable_opts[4] = { 48 {{1, 1}, {0, 0}}, 49 {{1, 1}, {0, 1}}, 50 {{1, 1}, {1, 0}}, 51 {{1, 1}, {1, 1}}, 52 }; 53 54 int bind_port(struct __test_metadata *_metadata, int reuseaddr, int reuseport) 55 { 56 struct sockaddr_in local_addr; 57 int len = sizeof(local_addr); 58 int fd, ret; 59 60 fd = socket(AF_INET, SOCK_STREAM, 0); 61 ASSERT_NE(-1, fd) TH_LOG("failed to open socket."); 62 63 ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, sizeof(int)); 64 ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEADDR."); 65 66 ret = setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &reuseport, sizeof(int)); 67 ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEPORT."); 68 69 local_addr.sin_family = AF_INET; 70 local_addr.sin_addr.s_addr = inet_addr("127.0.0.1"); 71 local_addr.sin_port = 0; 72 73 if (bind(fd, (struct sockaddr *)&local_addr, len) == -1) { 74 close(fd); 75 return -1; 76 } 77 78 return fd; 79 } 80 81 TEST(reuseaddr_ports_exhausted_unreusable) 82 { 83 struct reuse_opts *opts; 84 int i, j, fd[2]; 85 86 for (i = 0; i < 12; i++) { 87 opts = &unreusable_opts[i]; 88 89 for (j = 0; j < 2; j++) 90 fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); 91 92 ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); 93 EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind."); 94 95 for (j = 0; j < 2; j++) 96 if (fd[j] != -1) 97 close(fd[j]); 98 } 99 } 100 101 TEST(reuseaddr_ports_exhausted_reusable_same_euid) 102 { 103 struct reuse_opts *opts; 104 int i, j, fd[2]; 105 106 for (i = 0; i < 4; i++) { 107 opts = &reusable_opts[i]; 108 109 for (j = 0; j < 2; j++) 110 fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); 111 112 ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); 113 114 if (opts->reuseport[0] && opts->reuseport[1]) { 115 EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind because both sockets succeed to be listened."); 116 } else { 117 EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind to connect to different destinations."); 118 } 119 120 for (j = 0; j < 2; j++) 121 if (fd[j] != -1) 122 close(fd[j]); 123 } 124 } 125 126 TEST(reuseaddr_ports_exhausted_reusable_different_euid) 127 { 128 struct reuse_opts *opts; 129 int i, j, ret, fd[2]; 130 uid_t euid[2] = {10, 20}; 131 132 for (i = 0; i < 4; i++) { 133 opts = &reusable_opts[i]; 134 135 for (j = 0; j < 2; j++) { 136 ret = seteuid(euid[j]); 137 ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: %d.", euid[j]); 138 139 fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); 140 141 ret = seteuid(0); 142 ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: 0."); 143 } 144 145 ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); 146 EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind because one socket can be bound in each euid."); 147 148 if (fd[1] != -1) { 149 ret = listen(fd[0], 5); 150 ASSERT_EQ(0, ret) TH_LOG("failed to listen."); 151 152 ret = listen(fd[1], 5); 153 EXPECT_EQ(-1, ret) TH_LOG("should fail to listen because only one uid reserves the port in TCP_LISTEN."); 154 } 155 156 for (j = 0; j < 2; j++) 157 if (fd[j] != -1) 158 close(fd[j]); 159 } 160 } 161 162 TEST_HARNESS_MAIN 163