Add a regression test for the port-selection behavior fixed in r367680.

Reviewed by:	markj, olivier, tuexen
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D27173

tests/sys/netinet/Makefile

@@ -7,7 +7,8 @@ BINDIR=		${TESTSDIR}
 
 ATF_TESTS_C=	ip_reass_test \
 		so_reuseport_lb_test \
-		socket_afinet
+		socket_afinet \
+		tcp_connect_port_test
 
 ATF_TESTS_SH=	carp fibs fibs_test redirect divert forward output lpm
 TEST_METADATA.output+=	required_programs="python"

tests/sys/netinet/tcp_connect_port_test.c

@@ -0,0 +1,334 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Netflix, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/sysctl.h>
+
+#include <netinet/in.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <atf-c.h>
+
+#define	SYSCTLBAKFILE	"tmp.net.inet.ip.portrange.randomized"
+
+/*
+ * Check if port allocation is randomized. If so, update it. Save the old
+ * value of the sysctl so it can be updated later.
+ */
+static void
+disable_random_ports(void)
+{
+	int error, fd, random_new, random_save;
+	size_t sysctlsz;
+
+	/*
+	 * Pre-emptively unlink our restoration file, so we will do no
+	 * restoration on error.
+	 */
+	unlink(SYSCTLBAKFILE);
+
+	/*
+	 * Disable the net.inet.ip.portrange.randomized sysctl. Save the
+	 * old value so we can restore it, if necessary.
+	 */
+	random_new = 0;
+	sysctlsz = sizeof(random_save);
+	error = sysctlbyname("net.inet.ip.portrange.randomized", &random_save,
+	    &sysctlsz, &random_new, sizeof(random_new));
+	if (error) {
+		warn("sysctlbyname(\"net.inet.ip.portrange.randomized\") "
+		    "failed");
+		atf_tc_skip("Unable to set sysctl");
+	}
+	if (sysctlsz != sizeof(random_save)) {
+		fprintf(stderr, "Error: unexpected sysctl value size "
+		    "(expected %zu, actual %zu)\n", sizeof(random_save),
+		    sysctlsz);
+		goto restore_sysctl;
+	}
+
+	/* Open the backup file, write the contents, and close it. */
+	fd = open(SYSCTLBAKFILE, O_WRONLY|O_CREAT|O_TRUNC|O_EXCL,
+	    S_IRUSR|S_IWUSR);
+	if (fd < 0) {
+		warn("error opening sysctl backup file");
+		goto restore_sysctl;
+	}
+	error = write(fd, &random_save, sizeof(random_save));
+	if (error < 0) {
+		warn("error writing saved value to sysctl backup file");
+		goto cleanup_and_restore;
+	}
+	if (error != (int)sizeof(random_save)) {
+		fprintf(stderr,
+		    "Error writing saved value to sysctl backup file: "
+		    "(expected %zu, actual %d)\n", sizeof(random_save), error);
+		goto cleanup_and_restore;
+	}
+	error = close(fd);
+	if (error) {
+		warn("error closing sysctl backup file");
+cleanup_and_restore:
+		(void)close(fd);
+		(void)unlink(SYSCTLBAKFILE);
+restore_sysctl:
+		(void)sysctlbyname("net.inet.ip.portrange.randomized", NULL,
+		    NULL, &random_save, sysctlsz);
+		atf_tc_skip("Error setting sysctl");
+	}
+}
+
+/*
+ * Restore the sysctl value from the backup file and delete the backup file.
+ */
+static void
+restore_random_ports(void)
+{
+	int error, fd, random_save;
+
+	/* Open the backup file, read the contents, close it, and delete it. */
+	fd = open(SYSCTLBAKFILE, O_RDONLY);
+	if (fd < 0) {
+		warn("error opening sysctl backup file");
+		return;
+	}
+	error = read(fd, &random_save, sizeof(random_save));
+	if (error < 0) {
+		warn("error reading saved value from sysctl backup file");
+		return;
+	}
+	if (error != (int)sizeof(random_save)) {
+		fprintf(stderr,
+		    "Error reading saved value from sysctl backup file: "
+		    "(expected %zu, actual %d)\n", sizeof(random_save), error);
+		return;
+	}
+	error = close(fd);
+	if (error)
+		warn("error closing sysctl backup file");
+	error = unlink(SYSCTLBAKFILE);
+	if (error)
+		warn("error removing sysctl backup file");
+
+	/* Restore the saved sysctl value. */
+	error = sysctlbyname("net.inet.ip.portrange.randomized", NULL, NULL,
+	    &random_save, sizeof(random_save));
+	if (error)
+		warn("sysctlbyname(\"net.inet.ip.portrange.randomized\") "
+		    "failed while restoring value");
+}
+
+/*
+ * Given a domain and sockaddr, open a listening socket with automatic port
+ * selection. Then, try to connect 64K times. Ensure the connected socket never
+ * uses an overlapping port.
+ */
+static void
+connect_loop(int domain, const struct sockaddr *addr)
+{
+	union {
+		struct sockaddr saddr;
+		struct sockaddr_in saddr4;
+		struct sockaddr_in6 saddr6;
+	} su_clnt, su_srvr;
+	socklen_t salen;
+	int asock, csock, error, i, lsock;
+	const struct linger lopt = { 1, 0 };
+
+	/*
+	 * Disable the net.inet.ip.portrange.randomized sysctl. Assuming an
+	 * otherwise idle system, this makes the kernel try all possible
+	 * ports sequentially and makes it more likely it will try the
+	 * port on which we have a listening socket.
+	 */
+	disable_random_ports();
+
+	/* Setup the listen socket. */
+	lsock = socket(domain, SOCK_STREAM, 0);
+	ATF_REQUIRE_MSG(lsock >= 0, "socket() for listen socket failed: %s",
+	    strerror(errno));
+	error = bind(lsock, addr, addr->sa_len);
+	ATF_REQUIRE_MSG(error == 0, "bind() failed: %s", strerror(errno));
+	error = listen(lsock, 1);
+	ATF_REQUIRE_MSG(error == 0, "listen() failed: %s", strerror(errno));
+
+	/*
+	 * Get the address of the listen socket, which will be the destination
+	 * address for our connection attempts.
+	 */
+	salen = sizeof(su_srvr);
+	error = getsockname(lsock, &su_srvr.saddr, &salen);
+	ATF_REQUIRE_MSG(error == 0,
+	    "getsockname() for listen socket failed: %s",
+	    strerror(errno));
+	ATF_REQUIRE_MSG(salen == (domain == PF_INET ?
+	    sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
+	    "unexpected sockaddr size");
+	ATF_REQUIRE_MSG(su_srvr.saddr.sa_len == (domain == PF_INET ?
+	    sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
+	    "unexpected sa_len size");
+
+	/* Open 64K connections in a loop. */
+	for (i = 0; i < 65536; i++) {
+		csock = socket(domain, SOCK_STREAM, 0);
+		ATF_REQUIRE_MSG(csock >= 0,
+		    "socket() for client socket %d failed: %s",
+		    i, strerror(errno));
+
+		error = connect(csock, &su_srvr.saddr, su_srvr.saddr.sa_len);
+		ATF_REQUIRE_MSG(error == 0,
+		    "connect() for client socket %d failed: %s",
+		    i, strerror(errno));
+
+		error = setsockopt(csock, SOL_SOCKET, SO_LINGER, &lopt,
+		    sizeof(lopt));
+		ATF_REQUIRE_MSG(error == 0,
+		    "Setting linger for client socket %d failed: %s",
+		    i, strerror(errno));
+
+		/* Ascertain the client socket address. */
+		salen = sizeof(su_clnt);
+		error = getsockname(csock, &su_clnt.saddr, &salen);
+		ATF_REQUIRE_MSG(error == 0,
+		    "getsockname() for client socket %d failed: %s",
+		    i, strerror(errno));
+		ATF_REQUIRE_MSG(salen == (domain == PF_INET ?
+		    sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)),
+		    "unexpected sockaddr size for client socket %d", i);
+
+		/* Ensure the ports do not match. */
+		switch (domain) {
+		case PF_INET:
+			ATF_REQUIRE_MSG(su_clnt.saddr4.sin_port !=
+			    su_srvr.saddr4.sin_port,
+			    "client socket %d using the same port as server",
+			    i);
+			break;
+		case PF_INET6:
+			ATF_REQUIRE_MSG(su_clnt.saddr6.sin6_port !=
+			    su_srvr.saddr6.sin6_port,
+			    "client socket %d using the same port as server",
+			    i);
+			break;
+		}
+
+		/* Accept the socket and close both ends. */
+		asock = accept(lsock, NULL, NULL);
+		ATF_REQUIRE_MSG(asock >= 0,
+		    "accept() failed for client socket %d: %s",
+		    i, strerror(errno));
+
+		error = close(asock);
+		ATF_REQUIRE_MSG(error == 0,
+		    "close() failed for accepted socket %d: %s",
+		    i, strerror(errno));
+
+		error = close(csock);
+		ATF_REQUIRE_MSG(error == 0,
+		    "close() failed for client socket %d: %s",
+		    i, strerror(errno));
+	}
+}
+
+ATF_TC_WITH_CLEANUP(basic_ipv4);
+ATF_TC_HEAD(basic_ipv4, tc)
+{
+
+	atf_tc_set_md_var(tc, "require.user", "root");
+	atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
+	atf_tc_set_md_var(tc, "descr",
+	    "Check automatic local port assignment during TCP connect calls");
+}
+
+ATF_TC_BODY(basic_ipv4, tc)
+{
+	struct sockaddr_in saddr4;
+
+	memset(&saddr4, 0, sizeof(saddr4));
+	saddr4.sin_len = sizeof(saddr4);
+	saddr4.sin_family = AF_INET;
+	saddr4.sin_port = htons(0);
+	saddr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+
+	connect_loop(PF_INET, (const struct sockaddr *)&saddr4);
+}
+
+ATF_TC_CLEANUP(basic_ipv4, tc)
+{
+
+	restore_random_ports();
+}
+
+ATF_TC_WITH_CLEANUP(basic_ipv6);
+ATF_TC_HEAD(basic_ipv6, tc)
+{
+
+	atf_tc_set_md_var(tc, "require.user", "root");
+	atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
+	atf_tc_set_md_var(tc, "descr",
+	    "Check automatic local port assignment during TCP connect calls");
+}
+
+ATF_TC_BODY(basic_ipv6, tc)
+{
+	struct sockaddr_in6 saddr6;
+
+	memset(&saddr6, 0, sizeof(saddr6));
+	saddr6.sin6_len = sizeof(saddr6);
+	saddr6.sin6_family = AF_INET6;
+	saddr6.sin6_port = htons(0);
+	saddr6.sin6_addr = in6addr_loopback;
+
+	connect_loop(PF_INET6, (const struct sockaddr *)&saddr6);
+}
+
+ATF_TC_CLEANUP(basic_ipv6, tc)
+{
+
+	restore_random_ports();
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, basic_ipv4);
+	ATF_TP_ADD_TC(tp, basic_ipv6);
+
+	return (atf_no_error());
+}
+