[PATCH net-next v3 4/5] selftests: net: test IPV6_FL_F_REFLECT
From: Marcelo Mendes Spessoto Junior <hidden>
Date: 2026-08-07 22:10:10
Also in:
linux-kselftest, lkml
Subsystem:
kernel selftest framework, networking [general], the rest · Maintainers:
Shuah Khan, Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
According to the source code, flowlabel_consistency must be deactivated for the IPV6_FL_F_REFLECT flag to work. Since ipv6_flowlabel_mgr now runs in its own network namespace, do this directly from the test binary. Attempt to disable net.ipv6.flowlabel_consistency and skip the reflect test if that fails. A disabled flowlabel_consistency does not affect the remaining features being tested on the file, and failing to disable is not fatal and skips the reflect test only. The previously defined tcp_listen and tcp_connect helpers were reused, since the connection flow required for REFLECT validation is very similar to REMOTE. Signed-off-by: Marcelo Mendes Spessoto Junior <redacted> --- .../selftests/net/ipv6_flowlabel_mgr.c | 66 +++++++++++++++++++ 1 file changed, 66 insertions(+)
diff --git a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
index f8d8b09b9d86..d32150abd8ff 100644
--- a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
+++ b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c@@ -6,6 +6,7 @@ #include <arpa/inet.h> #include <error.h> #include <errno.h> +#include <fcntl.h> #include <limits.h> #include <linux/in6.h> #include <net/if.h>
@@ -168,6 +169,23 @@ static void tcp_connect(int listener, uint32_t flowlabel, *accepted = afd; } +static bool disable_flowlabel_consistency(void) +{ + int fd; + + fd = open("/proc/sys/net/ipv6/flowlabel_consistency", O_WRONLY); + if (fd == -1) + return false; + + if (write(fd, "0", 1) != 1) { + close(fd); + return false; + } + close(fd); + + return true; +} + static void run_tests(int fd) { int wstatus;
@@ -307,6 +325,54 @@ static void run_tests(int fd) close(remote_cfd); close(remote_listener); } + + if (!disable_flowlabel_consistency()) { + fprintf(stderr, + "[INFO] skip REFLECT: cannot disable net.ipv6.flowlabel_consistency\n"); + } else { + struct in6_flowlabel_req reflect_query = { + .flr_action = IPV6_FL_A_GET, + }; + struct in6_flowlabel_req reflect_off = { + .flr_action = IPV6_FL_A_PUT, + .flr_flags = IPV6_FL_F_REFLECT, + }; + struct in6_flowlabel_req reflect_on = { + .flr_action = IPV6_FL_A_GET, + .flr_flags = IPV6_FL_F_REFLECT, + }; + socklen_t reflect_query_len = sizeof(reflect_query); + int reflect_listener = tcp_listen(); + int reflect_cfd, reflect_afd; + + explain("Enable REFLECT on listener before client connects"); + expect_pass(setsockopt(reflect_listener, SOL_IPV6, + IPV6_FLOWLABEL_MGR, &reflect_on, + sizeof(reflect_on))); + + tcp_connect(reflect_listener, 8, &reflect_cfd, &reflect_afd); + + explain("accepted socket's label should be reflected"); + expect_pass(getsockopt(reflect_afd, SOL_IPV6, + IPV6_FLOWLABEL_MGR, &reflect_query, + &reflect_query_len)); + if (ntohl(reflect_query.flr_label) != 8) + error(1, 0, "unexpected reflected flowlabel %u", + ntohl(reflect_query.flr_label)); + + explain("PUT+REFLECT disables reflection on accepted socket"); + expect_pass(setsockopt(reflect_afd, SOL_IPV6, + IPV6_FLOWLABEL_MGR, &reflect_off, + sizeof(reflect_off))); + explain("cannot disable reflection twice"); + expect_fail(setsockopt(reflect_afd, SOL_IPV6, + IPV6_FLOWLABEL_MGR, &reflect_off, + sizeof(reflect_off))); + + close(reflect_afd); + close(reflect_cfd); + close(reflect_listener); + } } static void setup(void)
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2.55.0