commit 29f4801e9c8dfd12bdcb33b61a6ac479c7162bd7 upstream.

This validates the previous commit: the userspace can set unknown flags
-- the 7th bit is currently unused -- without errors, but only the
supported ones are printed in the endpoints dumps.

The 'Fixes' tag here below is the same as the one from the previous
commit: this patch here is not fixing anything wrong in the selftests,
but it validates the previous fix for an issue introduced by this commit
ID.

Fixes: 01cacb00b35c ("mptcp: add netlink-based PM")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-2-9e4781a6c1b8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts in pm_netlink.sh, because some refactoring have been done
  later on: commit 0d16ed0c2e74 ("selftests: mptcp: add
  {get,format}_endpoint(s) helpers") and commit c99d57d0007a
  ("selftests: mptcp: use pm_nl endpoint ops") are not in this version.
  The same operation can still be done at the same place, without using
  the new helpers.
  Also, commit 1dc88d241f92 ("selftests: mptcp: pm_nl_ctl: always look
  for errors") is not in this version, and create a conflict in the
  context which is not related to the modification here.
  In v5.10, endpoints couldn't be re-used directly, so the flag is
  tested before.
  Conflicts in pm_nl_ctl.c, because commit 69c6ce7b6eca ("selftests:
  mptcp: add implicit endpoint test case") and commit 371b90377e60
  ("selftests: mptcp: set and print the fullmesh flag") are not in this
  version, and caused a conflict in the context which is not related to
  the modification here. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/pm_netlink.sh |  2 +-
 tools/testing/selftests/net/mptcp/pm_nl_ctl.c   | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 7d194f5c2939..9d95d7e5b70a 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -80,7 +80,7 @@ if mptcp_lib_expect_all_features; then
 subflows 0" "defaults limits"
 fi
 
-ip netns exec $ns1 ./pm_nl_ctl add 10.0.1.1
+ip netns exec $ns1 ./pm_nl_ctl add 10.0.1.1 flags unknown
 ip netns exec $ns1 ./pm_nl_ctl add 10.0.1.2 flags subflow dev lo
 ip netns exec $ns1 ./pm_nl_ctl add 10.0.1.3 flags signal,backup
 check "ip netns exec $ns1 ./pm_nl_ctl get 1" "id 1 flags  10.0.1.1" "simple add/get addr"
diff --git a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
index b24a2f17d415..c6d7e0f2a8b8 100644
--- a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
+++ b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
@@ -22,6 +22,8 @@
 #define MPTCP_PM_NAME		"mptcp_pm"
 #endif
 
+#define MPTCP_PM_ADDR_FLAG_UNKNOWN _BITUL(7)
+
 static void syntax(char *argv[])
 {
 	fprintf(stderr, "%s add|get|del|flush|dump|accept [<args>]\n", argv[0]);
@@ -236,6 +238,8 @@ int add_addr(int fd, int pm_family, int argc, char *argv[])
 					flags |= MPTCP_PM_ADDR_FLAG_SIGNAL;
 				else if (!strcmp(tok, "backup"))
 					flags |= MPTCP_PM_ADDR_FLAG_BACKUP;
+				else if (!strcmp(tok, "unknown"))
+					flags |= MPTCP_PM_ADDR_FLAG_UNKNOWN;
 				else
 					error(1, errno,
 					      "unknown flag %s", argv[arg]);
@@ -373,6 +377,13 @@ static void print_addr(struct rtattr *attrs, int len)
 					printf(",");
 			}
 
+			if (flags & MPTCP_PM_ADDR_FLAG_UNKNOWN) {
+				printf("unknown");
+				flags &= ~MPTCP_PM_ADDR_FLAG_UNKNOWN;
+				if (flags)
+					printf(",");
+			}
+
 			/* bump unknown flags, if any */
 			if (flags)
 				printf("0x%x", flags);
-- 
2.51.0