selftest: af_unix: Add msg_oob.c.

AF_UNIX's MSG_OOB functionality lacked thorough testing, and we found
some bizarre behaviour.

The new selftest validates every MSG_OOB operation against TCP as a
reference implementation.

This patch adds only a few tests with basic send() and recv() that
do not fail.

The following patches will add more test cases for SO_OOBINLINE, SIGURG,
EPOLLPRI, and SIOCATMARK.

Signed-off-by: Kuniyuki Iwashima <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>

tools/testing/selftests/net/af_unix/Makefile

···
 CFLAGS += $(KHDR_INCLUDES)
-TEST_GEN_PROGS := diag_uid scm_pidfd scm_rights unix_connect
+TEST_GEN_PROGS := diag_uid msg_oob scm_pidfd scm_rights unix_connect
 
 include ../../lib.mk

tools/testing/selftests/net/af_unix/msg_oob.c

···
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Amazon.com Inc. or its affiliates. */
+
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "../../kselftest_harness.h"
+
+#define BUF_SZ	32
+
+FIXTURE(msg_oob)
+{
+	int fd[4];		/* 0: AF_UNIX sender
+				 * 1: AF_UNIX receiver
+				 * 2: TCP sender
+				 * 3: TCP receiver
+				 */
+};
+
+static void create_unix_socketpair(struct __test_metadata *_metadata,
+				   FIXTURE_DATA(msg_oob) *self)
+{
+	int ret;
+
+	ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, self->fd);
+	ASSERT_EQ(ret, 0);
+}
+
+static void create_tcp_socketpair(struct __test_metadata *_metadata,
+				  FIXTURE_DATA(msg_oob) *self)
+{
+	struct sockaddr_in addr;
+	socklen_t addrlen;
+	int listen_fd;
+	int ret;
+
+	listen_fd = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GE(listen_fd, 0);
+
+	ret = listen(listen_fd, -1);
+	ASSERT_EQ(ret, 0);
+
+	addrlen = sizeof(addr);
+	ret = getsockname(listen_fd, (struct sockaddr *)&addr, &addrlen);
+	ASSERT_EQ(ret, 0);
+
+	self->fd[2] = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GE(self->fd[2], 0);
+
+	ret = connect(self->fd[2], (struct sockaddr *)&addr, addrlen);
+	ASSERT_EQ(ret, 0);
+
+	self->fd[3] = accept(listen_fd, (struct sockaddr *)&addr, &addrlen);
+	ASSERT_GE(self->fd[3], 0);
+
+	ret = fcntl(self->fd[3], F_SETFL, O_NONBLOCK);
+	ASSERT_EQ(ret, 0);
+}
+
+static void close_sockets(FIXTURE_DATA(msg_oob) *self)
+{
+	int i;
+
+	for (i = 0; i < 4; i++)
+		close(self->fd[i]);
+}
+
+FIXTURE_SETUP(msg_oob)
+{
+	create_unix_socketpair(_metadata, self);
+	create_tcp_socketpair(_metadata, self);
+}
+
+FIXTURE_TEARDOWN(msg_oob)
+{
+	close_sockets(self);
+}
+
+static void __sendpair(struct __test_metadata *_metadata,
+		       FIXTURE_DATA(msg_oob) *self,
+		       const void *buf, size_t len, int flags)
+{
+	int i, ret[2];
+
+	for (i = 0; i < 2; i++)
+		ret[i] = send(self->fd[i * 2], buf, len, flags);
+
+	ASSERT_EQ(ret[0], len);
+	ASSERT_EQ(ret[0], ret[1]);
+}
+
+static void __recvpair(struct __test_metadata *_metadata,
+		       FIXTURE_DATA(msg_oob) *self,
+		       const void *expected_buf, int expected_len,
+		       int buf_len, int flags)
+{
+	int i, ret[2], recv_errno[2], expected_errno = 0;
+	char recv_buf[2][BUF_SZ] = {};
+
+	ASSERT_GE(BUF_SZ, buf_len);
+
+	errno = 0;
+
+	for (i = 0; i < 2; i++) {
+		ret[i] = recv(self->fd[i * 2 + 1], recv_buf[i], buf_len, flags);
+		recv_errno[i] = errno;
+	}
+
+	if (expected_len < 0) {
+		expected_errno = -expected_len;
+		expected_len = -1;
+	}
+
+	if (ret[0] != expected_len || recv_errno[0] != expected_errno) {
+		TH_LOG("AF_UNIX :%s", ret[0] < 0 ? strerror(recv_errno[0]) : recv_buf[0]);
+		TH_LOG("Expected:%s", expected_errno ? strerror(expected_errno) : expected_buf);
+
+		ASSERT_EQ(ret[0], expected_len);
+		ASSERT_EQ(recv_errno[0], expected_errno);
+	}
+
+	if (ret[0] != ret[1] || recv_errno[0] != recv_errno[1]) {
+		TH_LOG("AF_UNIX :%s", ret[0] < 0 ? strerror(recv_errno[0]) : recv_buf[0]);
+		TH_LOG("TCP     :%s", ret[1] < 0 ? strerror(recv_errno[1]) : recv_buf[1]);
+
+		ASSERT_EQ(ret[0], ret[1]);
+		ASSERT_EQ(recv_errno[0], recv_errno[1]);
+	}
+
+	if (expected_len >= 0) {
+		int cmp;
+
+		cmp = strncmp(expected_buf, recv_buf[0], expected_len);
+		if (cmp) {
+			TH_LOG("AF_UNIX :%s", ret[0] < 0 ? strerror(recv_errno[0]) : recv_buf[0]);
+			TH_LOG("Expected:%s", expected_errno ? strerror(expected_errno) : expected_buf);
+
+			ASSERT_EQ(cmp, 0);
+		}
+
+		cmp = strncmp(recv_buf[0], recv_buf[1], expected_len);
+		if (cmp) {
+			TH_LOG("AF_UNIX :%s", ret[0] < 0 ? strerror(recv_errno[0]) : recv_buf[0]);
+			TH_LOG("TCP     :%s", ret[1] < 0 ? strerror(recv_errno[1]) : recv_buf[1]);
+
+			ASSERT_EQ(cmp, 0);
+		}
+	}
+}
+
+#define sendpair(buf, len, flags)					\
+	__sendpair(_metadata, self, buf, len, flags)
+
+#define recvpair(expected_buf, expected_len, buf_len, flags)		\
+	__recvpair(_metadata, self,					\
+		   expected_buf, expected_len, buf_len, flags)
+
+TEST_F(msg_oob, non_oob)
+{
+	sendpair("x", 1, 0);
+
+	recvpair("", -EINVAL, 1, MSG_OOB);
+}
+
+TEST_F(msg_oob, oob)
+{
+	sendpair("x", 1, MSG_OOB);
+
+	recvpair("x", 1, 1, MSG_OOB);
+}
+
+TEST_F(msg_oob, oob_drop)
+{
+	sendpair("x", 1, MSG_OOB);
+
+	recvpair("", -EAGAIN, 1, 0);		/* Drop OOB. */
+	recvpair("", -EINVAL, 1, MSG_OOB);
+}
+
+TEST_F(msg_oob, oob_ahead)
+{
+	sendpair("hello", 5, MSG_OOB);
+
+	recvpair("o", 1, 1, MSG_OOB);
+	recvpair("hell", 4, 4, 0);
+}
+
+TEST_F(msg_oob, oob_break)
+{
+	sendpair("hello", 5, MSG_OOB);
+
+	recvpair("hell", 4, 5, 0);		/* Break at OOB even with enough buffer. */
+	recvpair("o", 1, 1, MSG_OOB);
+}
+
+TEST_F(msg_oob, oob_ahead_break)
+{
+	sendpair("hello", 5, MSG_OOB);
+	sendpair("world", 5, 0);
+
+	recvpair("o", 1, 1, MSG_OOB);
+	recvpair("hell", 4, 9, 0);		/* Break at OOB even after it's recv()ed. */
+	recvpair("world", 5, 5, 0);
+}
+
+TEST_F(msg_oob, oob_break_drop)
+{
+	sendpair("hello", 5, MSG_OOB);
+	sendpair("world", 5, 0);
+
+	recvpair("hell", 4, 10, 0);		/* Break at OOB even with enough buffer. */
+	recvpair("world", 5, 10, 0);		/* Drop OOB and recv() the next skb. */
+	recvpair("", -EINVAL, 1, MSG_OOB);
+}
+
+TEST_HARNESS_MAIN