1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2020 Netflix, Inc.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/socket.h>
31 #include <sys/stat.h>
32 #include <sys/sysctl.h>
33
34 #include <netinet/in.h>
35
36 #include <err.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <unistd.h>
42
43 #include <atf-c.h>
44
45 #define SYSCTLBAKFILE "tmp.net.inet.ip.portrange.randomized"
46
47 /*
48 * Check if port allocation is randomized. If so, update it. Save the old
49 * value of the sysctl so it can be updated later.
50 */
51 static void
disable_random_ports(void)52 disable_random_ports(void)
53 {
54 int error, fd, random_new, random_save;
55 size_t sysctlsz;
56
57 /*
58 * Pre-emptively unlink our restoration file, so we will do no
59 * restoration on error.
60 */
61 unlink(SYSCTLBAKFILE);
62
63 /*
64 * Disable the net.inet.ip.portrange.randomized sysctl. Save the
65 * old value so we can restore it, if necessary.
66 */
67 random_new = 0;
68 sysctlsz = sizeof(random_save);
69 error = sysctlbyname("net.inet.ip.portrange.randomized", &random_save,
70 &sysctlsz, &random_new, sizeof(random_new));
71 if (error) {
72 warn("sysctlbyname(\"net.inet.ip.portrange.randomized\") "
73 "failed");
74 atf_tc_skip("Unable to set sysctl");
75 }
76 if (sysctlsz != sizeof(random_save)) {
77 fprintf(stderr, "Error: unexpected sysctl value size "
78 "(expected %zu, actual %zu)\n", sizeof(random_save),
79 sysctlsz);
80 goto restore_sysctl;
81 }
82
83 /* Open the backup file, write the contents, and close it. */
84 fd = open(SYSCTLBAKFILE, O_WRONLY|O_CREAT|O_TRUNC|O_EXCL,
85 S_IRUSR|S_IWUSR);
86 if (fd < 0) {
87 warn("error opening sysctl backup file");
88 goto restore_sysctl;
89 }
90 error = write(fd, &random_save, sizeof(random_save));
91 if (error < 0) {
92 warn("error writing saved value to sysctl backup file");
93 goto cleanup_and_restore;
94 }
95 if (error != (int)sizeof(random_save)) {
96 fprintf(stderr,
97 "Error writing saved value to sysctl backup file: "
98 "(expected %zu, actual %d)\n", sizeof(random_save), error);
99 goto cleanup_and_restore;
100 }
101 error = close(fd);
102 if (error) {
103 warn("error closing sysctl backup file");
104 cleanup_and_restore:
105 (void)close(fd);
106 (void)unlink(SYSCTLBAKFILE);
107 restore_sysctl:
108 (void)sysctlbyname("net.inet.ip.portrange.randomized", NULL,
109 NULL, &random_save, sysctlsz);
110 atf_tc_skip("Error setting sysctl");
111 }
112 }
113
114 /*
115 * Restore the sysctl value from the backup file and delete the backup file.
116 */
117 static void
restore_random_ports(void)118 restore_random_ports(void)
119 {
120 int error, fd, random_save;
121
122 /* Open the backup file, read the contents, close it, and delete it. */
123 fd = open(SYSCTLBAKFILE, O_RDONLY);
124 if (fd < 0) {
125 warn("error opening sysctl backup file");
126 return;
127 }
128 error = read(fd, &random_save, sizeof(random_save));
129 if (error < 0) {
130 warn("error reading saved value from sysctl backup file");
131 return;
132 }
133 if (error != (int)sizeof(random_save)) {
134 fprintf(stderr,
135 "Error reading saved value from sysctl backup file: "
136 "(expected %zu, actual %d)\n", sizeof(random_save), error);
137 return;
138 }
139 error = close(fd);
140 if (error)
141 warn("error closing sysctl backup file");
142 error = unlink(SYSCTLBAKFILE);
143 if (error)
144 warn("error removing sysctl backup file");
145
146 /* Restore the saved sysctl value. */
147 error = sysctlbyname("net.inet.ip.portrange.randomized", NULL, NULL,
148 &random_save, sizeof(random_save));
149 if (error)
150 warn("sysctlbyname(\"net.inet.ip.portrange.randomized\") "
151 "failed while restoring value");
152 }
153
154 /*
155 * Given a domain and sockaddr, open a listening socket with automatic port
156 * selection. Then, try to connect 64K times. Ensure the connected socket never
157 * uses an overlapping port.
158 */
159 static void
connect_loop(int domain,const struct sockaddr * addr)160 connect_loop(int domain, const struct sockaddr *addr)
161 {
162 union {
163 struct sockaddr saddr;
164 struct sockaddr_in saddr4;
165 struct sockaddr_in6 saddr6;
166 } su_clnt, su_srvr;
167 socklen_t salen;
168 int asock, csock, error, i, lsock;
169 const struct linger lopt = { 1, 0 };
170
171 /*
172 * Disable the net.inet.ip.portrange.randomized sysctl. Assuming an
173 * otherwise idle system, this makes the kernel try all possible
174 * ports sequentially and makes it more likely it will try the
175 * port on which we have a listening socket.
176 */
177 disable_random_ports();
178
179 /* Setup the listen socket. */
180 lsock = socket(domain, SOCK_STREAM, 0);
181 ATF_REQUIRE_MSG(lsock >= 0, "socket() for listen socket failed: %s",
182 strerror(errno));
183 error = bind(lsock, addr, addr->sa_len);
184 ATF_REQUIRE_MSG(error == 0, "bind() failed: %s", strerror(errno));
185 error = listen(lsock, 1);
186 ATF_REQUIRE_MSG(error == 0, "listen() failed: %s", strerror(errno));
187
188 /*
189 * Get the address of the listen socket, which will be the destination
190 * address for our connection attempts.
191 */
192 salen = sizeof(su_srvr);
193 error = getsockname(lsock, &su_srvr.saddr, &salen);
194 ATF_REQUIRE_MSG(error == 0,
195 "getsockname() for listen socket failed: %s",
196 strerror(errno));
197 ATF_REQUIRE_MSG(salen == (domain == PF_INET ?
198 sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
199 "unexpected sockaddr size");
200 ATF_REQUIRE_MSG(su_srvr.saddr.sa_len == (domain == PF_INET ?
201 sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
202 "unexpected sa_len size");
203
204 /* Open 64K connections in a loop. */
205 for (i = 0; i < 65536; i++) {
206 csock = socket(domain, SOCK_STREAM, 0);
207 ATF_REQUIRE_MSG(csock >= 0,
208 "socket() for client socket %d failed: %s",
209 i, strerror(errno));
210
211 error = connect(csock, &su_srvr.saddr, su_srvr.saddr.sa_len);
212 ATF_REQUIRE_MSG(error == 0,
213 "connect() for client socket %d failed: %s",
214 i, strerror(errno));
215
216 error = setsockopt(csock, SOL_SOCKET, SO_LINGER, &lopt,
217 sizeof(lopt));
218 ATF_REQUIRE_MSG(error == 0,
219 "Setting linger for client socket %d failed: %s",
220 i, strerror(errno));
221
222 /* Ascertain the client socket address. */
223 salen = sizeof(su_clnt);
224 error = getsockname(csock, &su_clnt.saddr, &salen);
225 ATF_REQUIRE_MSG(error == 0,
226 "getsockname() for client socket %d failed: %s",
227 i, strerror(errno));
228 ATF_REQUIRE_MSG(salen == (domain == PF_INET ?
229 sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
230 "unexpected sockaddr size for client socket %d", i);
231
232 /* Ensure the ports do not match. */
233 switch (domain) {
234 case PF_INET:
235 ATF_REQUIRE_MSG(su_clnt.saddr4.sin_port !=
236 su_srvr.saddr4.sin_port,
237 "client socket %d using the same port as server",
238 i);
239 break;
240 case PF_INET6:
241 ATF_REQUIRE_MSG(su_clnt.saddr6.sin6_port !=
242 su_srvr.saddr6.sin6_port,
243 "client socket %d using the same port as server",
244 i);
245 break;
246 }
247
248 /* Accept the socket and close both ends. */
249 asock = accept(lsock, NULL, NULL);
250 ATF_REQUIRE_MSG(asock >= 0,
251 "accept() failed for client socket %d: %s",
252 i, strerror(errno));
253
254 error = close(asock);
255 ATF_REQUIRE_MSG(error == 0,
256 "close() failed for accepted socket %d: %s",
257 i, strerror(errno));
258
259 error = close(csock);
260 ATF_REQUIRE_MSG(error == 0,
261 "close() failed for client socket %d: %s",
262 i, strerror(errno));
263 }
264 }
265
266 ATF_TC_WITH_CLEANUP(basic_ipv4);
ATF_TC_HEAD(basic_ipv4,tc)267 ATF_TC_HEAD(basic_ipv4, tc)
268 {
269
270 atf_tc_set_md_var(tc, "require.user", "root");
271 atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
272 atf_tc_set_md_var(tc, "descr",
273 "Check automatic local port assignment during TCP connect calls");
274 }
275
ATF_TC_BODY(basic_ipv4,tc)276 ATF_TC_BODY(basic_ipv4, tc)
277 {
278 struct sockaddr_in saddr4;
279
280 memset(&saddr4, 0, sizeof(saddr4));
281 saddr4.sin_len = sizeof(saddr4);
282 saddr4.sin_family = AF_INET;
283 saddr4.sin_port = htons(0);
284 saddr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
285
286 connect_loop(PF_INET, (const struct sockaddr *)&saddr4);
287 }
288
ATF_TC_CLEANUP(basic_ipv4,tc)289 ATF_TC_CLEANUP(basic_ipv4, tc)
290 {
291
292 restore_random_ports();
293 }
294
295 ATF_TC_WITH_CLEANUP(basic_ipv6);
ATF_TC_HEAD(basic_ipv6,tc)296 ATF_TC_HEAD(basic_ipv6, tc)
297 {
298
299 atf_tc_set_md_var(tc, "require.user", "root");
300 atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
301 atf_tc_set_md_var(tc, "descr",
302 "Check automatic local port assignment during TCP connect calls");
303 }
304
ATF_TC_BODY(basic_ipv6,tc)305 ATF_TC_BODY(basic_ipv6, tc)
306 {
307 struct sockaddr_in6 saddr6;
308
309 memset(&saddr6, 0, sizeof(saddr6));
310 saddr6.sin6_len = sizeof(saddr6);
311 saddr6.sin6_family = AF_INET6;
312 saddr6.sin6_port = htons(0);
313 saddr6.sin6_addr = in6addr_loopback;
314
315 connect_loop(PF_INET6, (const struct sockaddr *)&saddr6);
316 }
317
ATF_TC_CLEANUP(basic_ipv6,tc)318 ATF_TC_CLEANUP(basic_ipv6, tc)
319 {
320
321 restore_random_ports();
322 }
323
ATF_TP_ADD_TCS(tp)324 ATF_TP_ADD_TCS(tp)
325 {
326 ATF_TP_ADD_TC(tp, basic_ipv4);
327 ATF_TP_ADD_TC(tp, basic_ipv6);
328
329 return (atf_no_error());
330 }
331
332