selftests: net: add support for testing SO_RCVMARK and SO_RCVPRIORITY

Introduce tests to verify the correct functionality of the SO_RCVMARK and
SO_RCVPRIORITY socket options.

Suggested-by: Jakub Kicinski <[e-mail]>
Suggested-by: Ferenc Fejes <[e-mail]>
Signed-off-by: Anna Emese Nyiri <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Reviewed-by: Ido Schimmel <[e-mail]>
Tested-by: Ido Schimmel <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/.gitignore

···
 so_incoming_cpu
 so_netns_cookie
 so_txtime
+so_rcv_listener
 stress_reuseport_listen
 tap
 tcp_fastopen_backup_key

tools/testing/selftests/net/Makefile

···
 TEST_PROGS += gre_gso.sh
 TEST_PROGS += cmsg_so_mark.sh
 TEST_PROGS += cmsg_so_priority.sh
+TEST_PROGS += test_so_rcv.sh
 TEST_PROGS += cmsg_time.sh cmsg_ipv6.sh
 TEST_PROGS += netns-name.sh
 TEST_PROGS += nl_netdev.py
···
 TEST_GEN_FILES += toeplitz
 TEST_GEN_FILES += cmsg_sender
 TEST_GEN_FILES += stress_reuseport_listen
+TEST_GEN_FILES += so_rcv_listener
 TEST_PROGS += test_vxlan_vnifiltering.sh
 TEST_GEN_FILES += io_uring_zerocopy_tx
 TEST_PROGS += io_uring_zerocopy_tx.sh

tools/testing/selftests/net/so_rcv_listener.c

···
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <netdb.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#ifndef SO_RCVPRIORITY
+#define SO_RCVPRIORITY 82
+#endif
+
+struct options {
+	__u32 val;
+	int name;
+	int rcvname;
+	const char *host;
+	const char *service;
+} opt;
+
+static void __attribute__((noreturn)) usage(const char *bin)
+{
+	printf("Usage: %s [opts] <dst host> <dst port / service>\n", bin);
+	printf("Options:\n"
+		"\t\t-M val  Test SO_RCVMARK\n"
+		"\t\t-P val  Test SO_RCVPRIORITY\n"
+		"");
+	exit(EXIT_FAILURE);
+}
+
+static void parse_args(int argc, char *argv[])
+{
+	int o;
+
+	while ((o = getopt(argc, argv, "M:P:")) != -1) {
+		switch (o) {
+		case 'M':
+			opt.val = atoi(optarg);
+			opt.name = SO_MARK;
+			opt.rcvname = SO_RCVMARK;
+			break;
+		case 'P':
+			opt.val = atoi(optarg);
+			opt.name = SO_PRIORITY;
+			opt.rcvname = SO_RCVPRIORITY;
+			break;
+		default:
+			usage(argv[0]);
+			break;
+		}
+	}
+
+	if (optind != argc - 2)
+		usage(argv[0]);
+
+	opt.host = argv[optind];
+	opt.service = argv[optind + 1];
+}
+
+int main(int argc, char *argv[])
+{
+	int err = 0;
+	int recv_fd = -1;
+	int ret_value = 0;
+	__u32 recv_val;
+	struct cmsghdr *cmsg;
+	char cbuf[CMSG_SPACE(sizeof(__u32))];
+	char recv_buf[CMSG_SPACE(sizeof(__u32))];
+	struct iovec iov[1];
+	struct msghdr msg;
+	struct sockaddr_in recv_addr4;
+	struct sockaddr_in6 recv_addr6;
+
+	parse_args(argc, argv);
+
+	int family = strchr(opt.host, ':') ? AF_INET6 : AF_INET;
+
+	recv_fd = socket(family, SOCK_DGRAM, IPPROTO_UDP);
+	if (recv_fd < 0) {
+		perror("Can't open recv socket");
+		ret_value = -errno;
+		goto cleanup;
+	}
+
+	err = setsockopt(recv_fd, SOL_SOCKET, opt.rcvname, &opt.val, sizeof(opt.val));
+	if (err < 0) {
+		perror("Recv setsockopt error");
+		ret_value = -errno;
+		goto cleanup;
+	}
+
+	if (family == AF_INET) {
+		memset(&recv_addr4, 0, sizeof(recv_addr4));
+		recv_addr4.sin_family = family;
+		recv_addr4.sin_port = htons(atoi(opt.service));
+
+		if (inet_pton(family, opt.host, &recv_addr4.sin_addr) <= 0) {
+			perror("Invalid IPV4 address");
+			ret_value = -errno;
+			goto cleanup;
+		}
+
+		err = bind(recv_fd, (struct sockaddr *)&recv_addr4, sizeof(recv_addr4));
+	} else {
+		memset(&recv_addr6, 0, sizeof(recv_addr6));
+		recv_addr6.sin6_family = family;
+		recv_addr6.sin6_port = htons(atoi(opt.service));
+
+		if (inet_pton(family, opt.host, &recv_addr6.sin6_addr) <= 0) {
+			perror("Invalid IPV6 address");
+			ret_value = -errno;
+			goto cleanup;
+		}
+
+		err = bind(recv_fd, (struct sockaddr *)&recv_addr6, sizeof(recv_addr6));
+	}
+
+	if (err < 0) {
+		perror("Recv bind error");
+		ret_value = -errno;
+		goto cleanup;
+	}
+
+	iov[0].iov_base = recv_buf;
+	iov[0].iov_len = sizeof(recv_buf);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+	msg.msg_control = cbuf;
+	msg.msg_controllen = sizeof(cbuf);
+
+	err = recvmsg(recv_fd, &msg, 0);
+	if (err < 0) {
+		perror("Message receive error");
+		ret_value = -errno;
+		goto cleanup;
+	}
+
+	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+		if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == opt.name) {
+			recv_val = *(__u32 *)CMSG_DATA(cmsg);
+			printf("Received value: %u\n", recv_val);
+
+			if (recv_val != opt.val) {
+				fprintf(stderr, "Error: expected value: %u, got: %u\n",
+					opt.val, recv_val);
+				ret_value = -EINVAL;
+			}
+			goto cleanup;
+		}
+	}
+
+	fprintf(stderr, "Error: No matching cmsg received\n");
+	ret_value = -ENOMSG;
+
+cleanup:
+	if (recv_fd >= 0)
+		close(recv_fd);
+
+	return ret_value;
+}

tools/testing/selftests/net/test_so_rcv.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source lib.sh
+
+HOSTS=("127.0.0.1" "::1")
+PORT=1234
+TOTAL_TESTS=0
+FAILED_TESTS=0
+
+declare -A TESTS=(
+	["SO_RCVPRIORITY"]="-P 2"
+	["SO_RCVMARK"]="-M 3"
+)
+
+check_result() {
+	((TOTAL_TESTS++))
+	if [ "$1" -ne 0 ]; then
+		((FAILED_TESTS++))
+	fi
+}
+
+cleanup()
+{
+	cleanup_ns $NS
+}
+
+trap cleanup EXIT
+
+setup_ns NS
+
+for HOST in "${HOSTS[@]}"; do
+	PROTOCOL="IPv4"
+	if [[ "$HOST" == "::1" ]]; then
+		PROTOCOL="IPv6"
+	fi
+	for test_name in "${!TESTS[@]}"; do
+		echo "Running $test_name test, $PROTOCOL"
+		arg=${TESTS[$test_name]}
+
+		ip netns exec $NS ./so_rcv_listener $arg $HOST $PORT &
+		LISTENER_PID=$!
+
+		sleep 0.5
+
+		if ! ip netns exec $NS ./cmsg_sender $arg $HOST $PORT; then
+			echo "Sender failed for $test_name, $PROTOCOL"
+			kill "$LISTENER_PID" 2>/dev/null
+			wait "$LISTENER_PID"
+			check_result 1
+			continue
+		fi
+
+		wait "$LISTENER_PID"
+		LISTENER_EXIT_CODE=$?
+
+		if [ "$LISTENER_EXIT_CODE" -eq 0 ]; then
+			echo "Rcv test OK for $test_name, $PROTOCOL"
+			check_result 0
+		else
+			echo "Rcv test FAILED for $test_name, $PROTOCOL"
+			check_result 1
+		fi
+	done
+done
+
+if [ "$FAILED_TESTS" -ne 0 ]; then
+	echo "FAIL - $FAILED_TESTS/$TOTAL_TESTS tests failed"
+	exit ${KSFT_FAIL}
+else
+	echo "OK - All $TOTAL_TESTS tests passed"
+	exit ${KSFT_PASS}
+fi