reuseaddr_ports_exhausted.c

  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 successfully 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