// SPDX-License-Identifier: GPL-2.0-only /* * Check if we can fully utilize 4-tuples for connect(). * * Rules to bind sockets to the same port when all ephemeral ports are * exhausted. * * 1. if there are TCP_LISTEN sockets on the port, fail to bind. * 2. if there are sockets without SO_REUSEADDR, fail to bind. * 3. if SO_REUSEADDR is disabled, fail to bind. * 4. if SO_REUSEADDR is enabled and SO_REUSEPORT is disabled, * succeed to bind. * 5. if SO_REUSEADDR and SO_REUSEPORT are enabled and * there is no socket having the both options and the same EUID, * succeed to bind. * 6. fail to bind. * * Author: Kuniyuki Iwashima */ #include #include #include #include #include #include "../kselftest_harness.h" struct reuse_opts { int reuseaddr[2]; int reuseport[2]; }; struct reuse_opts unreusable_opts[12] = { {0, 0, 0, 0}, {0, 0, 0, 1}, {0, 0, 1, 0}, {0, 0, 1, 1}, {0, 1, 0, 0}, {0, 1, 0, 1}, {0, 1, 1, 0}, {0, 1, 1, 1}, {1, 0, 0, 0}, {1, 0, 0, 1}, {1, 0, 1, 0}, {1, 0, 1, 1}, }; struct reuse_opts reusable_opts[4] = { {1, 1, 0, 0}, {1, 1, 0, 1}, {1, 1, 1, 0}, {1, 1, 1, 1}, }; int bind_port(struct __test_metadata *_metadata, int reuseaddr, int reuseport) { struct sockaddr_in local_addr; int len = sizeof(local_addr); int fd, ret; fd = socket(AF_INET, SOCK_STREAM, 0); ASSERT_NE(-1, fd) TH_LOG("failed to open socket."); ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, sizeof(int)); ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEADDR."); ret = setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &reuseport, sizeof(int)); ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEPORT."); local_addr.sin_family = AF_INET; local_addr.sin_addr.s_addr = inet_addr("127.0.0.1"); local_addr.sin_port = 0; if (bind(fd, (struct sockaddr *)&local_addr, len) == -1) { close(fd); return -1; } return fd; } TEST(reuseaddr_ports_exhausted_unreusable) { struct reuse_opts *opts; int i, j, fd[2]; for (i = 0; i < 12; i++) { opts = &unreusable_opts[i]; for (j = 0; j < 2; j++) fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind."); for (j = 0; j < 2; j++) if (fd[j] != -1) close(fd[j]); } } TEST(reuseaddr_ports_exhausted_reusable_same_euid) { struct reuse_opts *opts; int i, j, fd[2]; for (i = 0; i < 4; i++) { opts = &reusable_opts[i]; for (j = 0; j < 2; j++) fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); if (opts->reuseport[0] && opts->reuseport[1]) { EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind because both sockets succeed to be listened."); } else { EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind to connect to different destinations."); } for (j = 0; j < 2; j++) if (fd[j] != -1) close(fd[j]); } } TEST(reuseaddr_ports_exhausted_reusable_different_euid) { struct reuse_opts *opts; int i, j, ret, fd[2]; uid_t euid[2] = {10, 20}; for (i = 0; i < 4; i++) { opts = &reusable_opts[i]; for (j = 0; j < 2; j++) { ret = seteuid(euid[j]); ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: %d.", euid[j]); fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]); ret = seteuid(0); ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: 0."); } ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind."); EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind because one socket can be bound in each euid."); if (fd[1] != -1) { ret = listen(fd[0], 5); ASSERT_EQ(0, ret) TH_LOG("failed to listen."); ret = listen(fd[1], 5); EXPECT_EQ(-1, ret) TH_LOG("should fail to listen because only one uid reserves the port in TCP_LISTEN."); } for (j = 0; j < 2; j++) if (fd[j] != -1) close(fd[j]); } } TEST_HARNESS_MAIN