selftests/net: ipv6 flowlabel

Test the IPv6 flowlabel control and datapath interfaces:

Acquire and release the right to use flowlabels with socket option
IPV6_FLOWLABEL_MGR.

Then configure flowlabels on send and read them on recv with cmsg
IPV6_FLOWINFO. Also verify auto-flowlabel if not explicitly set.

This helped identify the issue fixed in commit 95c1692 ("ipv6:
invert flowlabel sharing check in process and user mode")

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/.gitignore

@@ -18,3 +18,5 @@ tls
 txring_overwrite
 ip_defrag
 so_txtime
+flowlabel
+flowlabel_mgr

tools/testing/selftests/net/Makefile

@@ -9,13 +9,13 @@ TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \
 TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh
 TEST_PROGS += udpgso_bench.sh fib_rule_tests.sh msg_zerocopy.sh psock_snd.sh
 TEST_PROGS += udpgro_bench.sh udpgro.sh test_vxlan_under_vrf.sh reuseport_addr_any.sh
-TEST_PROGS += test_vxlan_fdb_changelink.sh so_txtime.sh
+TEST_PROGS += test_vxlan_fdb_changelink.sh so_txtime.sh ipv6_flowlabel.sh
 TEST_PROGS_EXTENDED := in_netns.sh
 TEST_GEN_FILES =  socket
 TEST_GEN_FILES += psock_fanout psock_tpacket msg_zerocopy reuseport_addr_any
 TEST_GEN_FILES += tcp_mmap tcp_inq psock_snd txring_overwrite
 TEST_GEN_FILES += udpgso udpgso_bench_tx udpgso_bench_rx ip_defrag
-TEST_GEN_FILES += so_txtime
+TEST_GEN_FILES += so_txtime ipv6_flowlabel ipv6_flowlabel_mgr
 TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
 TEST_GEN_PROGS += reuseport_dualstack reuseaddr_conflict tls
 

tools/testing/selftests/net/ipv6_flowlabel.c

@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Test IPV6_FLOWINFO cmsg on send and recv */
+
+#define _GNU_SOURCE
+
+#include <arpa/inet.h>
+#include <asm/byteorder.h>
+#include <error.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <linux/in6.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* uapi/glibc weirdness may leave this undefined */
+#ifndef IPV6_FLOWINFO
+#define IPV6_FLOWINFO 11
+#endif
+
+#ifndef IPV6_FLOWLABEL_MGR
+#define IPV6_FLOWLABEL_MGR 32
+#endif
+
+#define FLOWLABEL_WILDCARD	((uint32_t) -1)
+
+static const char cfg_data[]	= "a";
+static uint32_t cfg_label	= 1;
+
+static void do_send(int fd, bool with_flowlabel, uint32_t flowlabel)
+{
+	char control[CMSG_SPACE(sizeof(flowlabel))] = {0};
+	struct msghdr msg = {0};
+	struct iovec iov = {0};
+	int ret;
+
+	iov.iov_base = (char *)cfg_data;
+	iov.iov_len = sizeof(cfg_data);
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	if (with_flowlabel) {
+		struct cmsghdr *cm;
+
+		cm = (void *)control;
+		cm->cmsg_len = CMSG_LEN(sizeof(flowlabel));
+		cm->cmsg_level = SOL_IPV6;
+		cm->cmsg_type = IPV6_FLOWINFO;
+		*(uint32_t *)CMSG_DATA(cm) = htonl(flowlabel);
+
+		msg.msg_control = control;
+		msg.msg_controllen = sizeof(control);
+	}
+
+	ret = sendmsg(fd, &msg, 0);
+	if (ret == -1)
+		error(1, errno, "send");
+
+	if (with_flowlabel)
+		fprintf(stderr, "sent with label %u\n", flowlabel);
+	else
+		fprintf(stderr, "sent without label\n");
+}
+
+static void do_recv(int fd, bool with_flowlabel, uint32_t expect)
+{
+	char control[CMSG_SPACE(sizeof(expect))];
+	char data[sizeof(cfg_data)];
+	struct msghdr msg = {0};
+	struct iovec iov = {0};
+	struct cmsghdr *cm;
+	uint32_t flowlabel;
+	int ret;
+
+	iov.iov_base = data;
+	iov.iov_len = sizeof(data);
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	memset(control, 0, sizeof(control));
+	msg.msg_control = control;
+	msg.msg_controllen = sizeof(control);
+
+	ret = recvmsg(fd, &msg, 0);
+	if (ret == -1)
+		error(1, errno, "recv");
+	if (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))
+		error(1, 0, "recv: truncated");
+	if (ret != sizeof(cfg_data))
+		error(1, 0, "recv: length mismatch");
+	if (memcmp(data, cfg_data, sizeof(data)))
+		error(1, 0, "recv: data mismatch");
+
+	cm = CMSG_FIRSTHDR(&msg);
+	if (with_flowlabel) {
+		if (!cm)
+			error(1, 0, "recv: missing cmsg");
+		if (CMSG_NXTHDR(&msg, cm))
+			error(1, 0, "recv: too many cmsg");
+		if (cm->cmsg_level != SOL_IPV6 ||
+		    cm->cmsg_type != IPV6_FLOWINFO)
+			error(1, 0, "recv: unexpected cmsg level or type");
+
+		flowlabel = ntohl(*(uint32_t *)CMSG_DATA(cm));
+		fprintf(stderr, "recv with label %u\n", flowlabel);
+
+		if (expect != FLOWLABEL_WILDCARD && expect != flowlabel)
+			fprintf(stderr, "recv: incorrect flowlabel %u != %u\n",
+					flowlabel, expect);
+
+	} else {
+		fprintf(stderr, "recv without label\n");
+	}
+}
+
+static bool get_autoflowlabel_enabled(void)
+{
+	int fd, ret;
+	char val;
+
+	fd = open("/proc/sys/net/ipv6/auto_flowlabels", O_RDONLY);
+	if (fd == -1)
+		error(1, errno, "open sysctl");
+
+	ret = read(fd, &val, 1);
+	if (ret == -1)
+		error(1, errno, "read sysctl");
+	if (ret == 0)
+		error(1, 0, "read sysctl: 0");
+
+	if (close(fd))
+		error(1, errno, "close sysctl");
+
+	return val == '1';
+}
+
+static void flowlabel_get(int fd, uint32_t label, uint8_t share, uint16_t flags)
+{
+	struct in6_flowlabel_req req = {
+		.flr_action = IPV6_FL_A_GET,
+		.flr_label = htonl(label),
+		.flr_flags = flags,
+		.flr_share = share,
+	};
+
+	/* do not pass IPV6_ADDR_ANY or IPV6_ADDR_MAPPED */
+	req.flr_dst.s6_addr[0] = 0xfd;
+	req.flr_dst.s6_addr[15] = 0x1;
+
+	if (setsockopt(fd, SOL_IPV6, IPV6_FLOWLABEL_MGR, &req, sizeof(req)))
+		error(1, errno, "setsockopt flowlabel get");
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int c;
+
+	while ((c = getopt(argc, argv, "l:")) != -1) {
+		switch (c) {
+		case 'l':
+			cfg_label = strtoul(optarg, NULL, 0);
+			break;
+		default:
+			error(1, 0, "%s: parse error", argv[0]);
+		}
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct sockaddr_in6 addr = {
+		.sin6_family = AF_INET6,
+		.sin6_port = htons(8000),
+		.sin6_addr = IN6ADDR_LOOPBACK_INIT,
+	};
+	const int one = 1;
+	int fdt, fdr;
+
+	parse_opts(argc, argv);
+
+	fdt = socket(PF_INET6, SOCK_DGRAM, 0);
+	if (fdt == -1)
+		error(1, errno, "socket t");
+
+	fdr = socket(PF_INET6, SOCK_DGRAM, 0);
+	if (fdr == -1)
+		error(1, errno, "socket r");
+
+	if (connect(fdt, (void *)&addr, sizeof(addr)))
+		error(1, errno, "connect");
+	if (bind(fdr, (void *)&addr, sizeof(addr)))
+		error(1, errno, "bind");
+
+	flowlabel_get(fdt, cfg_label, IPV6_FL_S_EXCL, IPV6_FL_F_CREATE);
+
+	if (setsockopt(fdr, SOL_IPV6, IPV6_FLOWINFO, &one, sizeof(one)))
+		error(1, errno, "setsockopt flowinfo");
+
+	if (get_autoflowlabel_enabled()) {
+		fprintf(stderr, "send no label: recv auto flowlabel\n");
+		do_send(fdt, false, 0);
+		do_recv(fdr, true, FLOWLABEL_WILDCARD);
+	} else {
+		fprintf(stderr, "send no label: recv no label (auto off)\n");
+		do_send(fdt, false, 0);
+		do_recv(fdr, false, 0);
+	}
+
+	fprintf(stderr, "send label\n");
+	do_send(fdt, true, cfg_label);
+	do_recv(fdr, true, cfg_label);
+
+	if (close(fdr))
+		error(1, errno, "close r");
+	if (close(fdt))
+		error(1, errno, "close t");
+
+	return 0;
+}

tools/testing/selftests/net/ipv6_flowlabel.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Regression tests for IPv6 flowlabels
+#
+# run in separate namespaces to avoid mgmt db conflicts betweent tests
+
+set -e
+
+echo "TEST management"
+./in_netns.sh ./ipv6_flowlabel_mgr
+
+echo "TEST datapath"
+./in_netns.sh \
+  sh -c 'sysctl -q -w net.ipv6.auto_flowlabels=0 && ./ipv6_flowlabel -l 1'
+
+echo "TEST datapath (with auto-flowlabels)"
+./in_netns.sh \
+  sh -c 'sysctl -q -w net.ipv6.auto_flowlabels=1 && ./ipv6_flowlabel -l 1'
+
+echo OK. All tests passed