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, reuseaddr: opts->reuseaddr[j], reuseport: 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, reuseaddr: opts->reuseaddr[j], reuseport: 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, reuseaddr: opts->reuseaddr[j], reuseport: 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 | |