selftests/net: Add sk_bind_sendto_listen and sk_connect_zero_addr

This patch adds 2 new tests: sk_bind_sendto_listen and
sk_connect_zero_addr.

The sk_bind_sendto_listen test exercises the path where a socket's
rcv saddr changes after it has been added to the binding tables,
and then a listen() on the socket is invoked. The listen() should
succeed.

The sk_bind_sendto_listen test is copied over from one of syzbot's
tests: https://syzkaller.appspot.com/x/repro.c?x=1673a38df00000

The sk_connect_zero_addr test exercises the path where the socket was
never previously added to the binding tables and it gets assigned a
saddr upon a connect() to address 0.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/.gitignore

@@ -41,3 +41,5 @@ cmsg_sender
 unix_connect
 tap
 bind_bhash
+sk_bind_sendto_listen
+sk_connect_zero_addr

tools/testing/selftests/net/Makefile

@@ -66,6 +66,8 @@ TEST_GEN_FILES += stress_reuseport_listen
 TEST_PROGS += test_vxlan_vnifiltering.sh
 TEST_GEN_FILES += io_uring_zerocopy_tx
 TEST_GEN_FILES += bind_bhash
+TEST_GEN_PROGS += sk_bind_sendto_listen
+TEST_GEN_PROGS += sk_connect_zero_addr
 
 TEST_FILES := settings
 

tools/testing/selftests/net/sk_bind_sendto_listen.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <arpa/inet.h>
+#include <error.h>
+#include <errno.h>
+#include <unistd.h>
+
+int main(void)
+{
+	int fd1, fd2, one = 1;
+	struct sockaddr_in6 bind_addr = {
+		.sin6_family = AF_INET6,
+		.sin6_port = htons(20000),
+		.sin6_flowinfo = htonl(0),
+		.sin6_addr = {},
+		.sin6_scope_id = 0,
+	};
+
+	inet_pton(AF_INET6, "::", &bind_addr.sin6_addr);
+
+	fd1 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP);
+	if (fd1 < 0) {
+		error(1, errno, "socket fd1");
+		return -1;
+	}
+
+	if (setsockopt(fd1, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one))) {
+		error(1, errno, "setsockopt(SO_REUSEADDR) fd1");
+		goto out_err1;
+	}
+
+	if (bind(fd1, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) {
+		error(1, errno, "bind fd1");
+		goto out_err1;
+	}
+
+	if (sendto(fd1, NULL, 0, MSG_FASTOPEN, (struct sockaddr *)&bind_addr,
+		   sizeof(bind_addr))) {
+		error(1, errno, "sendto fd1");
+		goto out_err1;
+	}
+
+	fd2 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP);
+	if (fd2 < 0) {
+		error(1, errno, "socket fd2");
+		goto out_err1;
+	}
+
+	if (setsockopt(fd2, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one))) {
+		error(1, errno, "setsockopt(SO_REUSEADDR) fd2");
+		goto out_err2;
+	}
+
+	if (bind(fd2, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) {
+		error(1, errno, "bind fd2");
+		goto out_err2;
+	}
+
+	if (sendto(fd2, NULL, 0, MSG_FASTOPEN, (struct sockaddr *)&bind_addr,
+		   sizeof(bind_addr)) != -1) {
+		error(1, errno, "sendto fd2");
+		goto out_err2;
+	}
+
+	if (listen(fd2, 0)) {
+		error(1, errno, "listen");
+		goto out_err2;
+	}
+
+	close(fd2);
+	close(fd1);
+	return 0;
+
+out_err2:
+	close(fd2);
+
+out_err1:
+	close(fd1);
+	return -1;
+}

tools/testing/selftests/net/sk_connect_zero_addr.c

@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <arpa/inet.h>
+#include <error.h>
+#include <errno.h>
+#include <unistd.h>
+
+int main(void)
+{
+	int fd1, fd2, one = 1;
+	struct sockaddr_in6 bind_addr = {
+		.sin6_family = AF_INET6,
+		.sin6_port = htons(20000),
+		.sin6_flowinfo = htonl(0),
+		.sin6_addr = {},
+		.sin6_scope_id = 0,
+	};
+
+	inet_pton(AF_INET6, "::", &bind_addr.sin6_addr);
+
+	fd1 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP);
+	if (fd1 < 0) {
+		error(1, errno, "socket fd1");
+		return -1;
+	}
+
+	if (setsockopt(fd1, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one))) {
+		error(1, errno, "setsockopt(SO_REUSEADDR) fd1");
+		goto out_err1;
+	}
+
+	if (bind(fd1, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) {
+		error(1, errno, "bind fd1");
+		goto out_err1;
+	}
+
+	if (listen(fd1, 0)) {
+		error(1, errno, "listen");
+		goto out_err1;
+	}
+
+	fd2 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP);
+	if (fd2 < 0) {
+		error(1, errno, "socket fd2");
+		goto out_err1;
+	}
+
+	if (connect(fd2, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) {
+		error(1, errno, "bind fd2");
+		goto out_err2;
+	}
+
+	close(fd2);
+	close(fd1);
+	return 0;
+
+out_err2:
+	close(fd2);
+out_err1:
+	close(fd1);
+	return -1;
+}