LXR linux/tools/testing/selftests/net/reuseaddr_ports

   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
  27struct reuse_opts {
  28        int reuseaddr[2];
  29        int reuseport[2];
  30};
  31
  32struct 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
  47struct 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
  54int 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
  81TEST(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
 101TEST(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
 126TEST(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
 162TEST_HARNESS_MAIN
 163