Merge branch 'mptcp-fix-inconsistent-backup-usage'

Matthieu Baerts says:

====================
mptcp: fix inconsistent backup usage

In all the MPTCP backup related tests, the backup flag was set on one
side, and the expected behaviour is to have both sides respecting this
decision. That's also the "natural" way, and what the users seem to
expect.

On the scheduler side, only the 'backup' field was checked, which is
supposed to be set only if the other peer flagged a subflow as backup.
But in various places, this flag was also set when the local host
flagged the subflow as backup, certainly to have the expected behaviour
mentioned above.

Patch 1 modifies the packet scheduler to check if the backup flag has
been set on both directions, not to change its behaviour after having
applied the following patches. That's what the default packet scheduler
should have done since the beginning in v5.7.

Patch 2 fixes the backup flag being mirrored on the MPJ+SYN+ACK by
accident since its introduction in v5.7. Instead, the received and sent
backup flags are properly distinguished in requests.

Patch 3 stops setting the received backup flag as well when sending an
MP_PRIO, something that was done since the MP_PRIO support in v5.12.

Patch 4 adds related and missing MIB counters to be able to easily check
if MP_JOIN are sent with a backup flag. Certainly because these counters
were not there, the behaviour that is fixed by patches here was not
properly verified.

Patch 5 validates the previous patch by extending the MPTCP Join
selftest.

Patch 6 fixes the backup support in signal endpoints: if a signal
endpoint had the backup flag, it was not set in the MPJ+SYN+ACK as
expected. It was only set for ongoing connections, but not future ones
as expected, since the introduction of the backup flag in endpoints in
v5.10.

Patch 7 validates the previous patch by extending the MPTCP Join
selftest as well.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Matthieu Baerts (NGI0) (7):
      mptcp: sched: check both directions for backup
      mptcp: distinguish rcv vs sent backup flag in requests
      mptcp: pm: only set request_bkup flag when sending MP_PRIO
      mptcp: mib: count MPJ with backup flag
      selftests: mptcp: join: validate backup in MPJ
      mptcp: pm: fix backup support in signal endpoints
      selftests: mptcp: join: check backup support in signal endp

 include/trace/events/mptcp.h                    |  2 +-
 net/mptcp/mib.c                                 |  2 +
 net/mptcp/mib.h                                 |  2 +
 net/mptcp/options.c                             |  2 +-
 net/mptcp/pm.c                                  | 12 +++++
 net/mptcp/pm_netlink.c                          | 19 ++++++-
 net/mptcp/pm_userspace.c                        | 18 +++++++
 net/mptcp/protocol.c                            | 10 ++--
 net/mptcp/protocol.h                            |  4 ++
 net/mptcp/subflow.c                             | 10 ++++
 tools/testing/selftests/net/mptcp/mptcp_join.sh | 72 ++++++++++++++++++++-----
 11 files changed, 132 insertions(+), 21 deletions(-)
====================

Link: https://patch.msgid.link/20240727-upstream-net-20240727-mptcp-backup-signal-v1-0-f50b31604cf1@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 58 insertions, 14 deletions

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 55d84a1bde15..4df48f1f14ab 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -1634,6 +1634,8 @@ chk_prio_nr()
 {
 	local mp_prio_nr_tx=$1
 	local mp_prio_nr_rx=$2
+	local mpj_syn=$3
+	local mpj_syn_ack=$4
 	local count
 
 	print_check "ptx"
@@ -1655,6 +1657,26 @@ chk_prio_nr()
 	else
 		print_ok
 	fi
+
+	print_check "syn backup"
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPJoinSynBackupRx")
+	if [ -z "$count" ]; then
+		print_skip
+	elif [ "$count" != "$mpj_syn" ]; then
+		fail_test "got $count JOIN[s] syn with Backup expected $mpj_syn"
+	else
+		print_ok
+	fi
+
+	print_check "synack backup"
+	count=$(mptcp_lib_get_counter ${ns2} "MPTcpExtMPJoinSynAckBackupRx")
+	if [ -z "$count" ]; then
+		print_skip
+	elif [ "$count" != "$mpj_syn_ack" ]; then
+		fail_test "got $count JOIN[s] synack with Backup expected $mpj_syn_ack"
+	else
+		print_ok
+	fi
 }
 
 chk_subflow_nr()
@@ -2612,33 +2634,46 @@ backup_tests()
 		sflags=nobackup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 1
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 	fi
 
 	# single address, backup
 	if reset "single address, backup" &&
 	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 0 1
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal,backup
+		pm_nl_set_limits $ns2 1 1
+		sflags=nobackup speed=slow \
+			run_tests $ns1 $ns2 10.0.1.1
+		chk_join_nr 1 1 1
+		chk_add_nr 1 1
+		chk_prio_nr 1 0 0 1
+	fi
+
+	# single address, switch to backup
+	if reset "single address, switch to backup" &&
+	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
+		pm_nl_set_limits $ns1 0 1
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
 		pm_nl_set_limits $ns2 1 1
 		sflags=backup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 1
 		chk_add_nr 1 1
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 
 	# single address with port, backup
 	if reset "single address with port, backup" &&
 	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 0 1
-		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal port 10100
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal,backup port 10100
 		pm_nl_set_limits $ns2 1 1
-		sflags=backup speed=slow \
+		sflags=nobackup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 1
 		chk_add_nr 1 1
-		chk_prio_nr 1 1
+		chk_prio_nr 1 0 0 1
 	fi
 
 	if reset "mpc backup" &&
@@ -2647,17 +2682,26 @@ backup_tests()
 		speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 0 0 0
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 0 0
 	fi
 
 	if reset "mpc backup both sides" &&
 	   continue_if mptcp_lib_kallsyms_doesnt_have "T mptcp_subflow_send_ack$"; then
-		pm_nl_add_endpoint $ns1 10.0.1.1 flags subflow,backup
+		pm_nl_set_limits $ns1 0 2
+		pm_nl_set_limits $ns2 1 2
+		pm_nl_add_endpoint $ns1 10.0.1.1 flags signal,backup
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,backup
+
+		# 10.0.2.2 (non-backup) -> 10.0.1.1 (backup)
+		pm_nl_add_endpoint $ns2 10.0.2.2 flags subflow
+		# 10.0.1.2 (backup) -> 10.0.2.1 (non-backup)
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
+		ip -net "$ns2" route add 10.0.2.1 via 10.0.1.1 dev ns2eth1 # force this path
+
 		speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
-		chk_join_nr 0 0 0
-		chk_prio_nr 1 1
+		chk_join_nr 2 2 2
+		chk_prio_nr 1 1 1 1
 	fi
 
 	if reset "mpc switch to backup" &&
@@ -2666,7 +2710,7 @@ backup_tests()
 		sflags=backup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 0 0 0
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 0 0
 	fi
 
 	if reset "mpc switch to backup both sides" &&
@@ -2676,7 +2720,7 @@ backup_tests()
 		sflags=backup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 0 0 0
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 }
 
@@ -3053,7 +3097,7 @@ fullmesh_tests()
 		addr_nr_ns2=1 sflags=backup,fullmesh speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 2 2 2
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 		chk_rm_nr 0 1
 	fi
 
@@ -3066,7 +3110,7 @@ fullmesh_tests()
 		sflags=nobackup,nofullmesh speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 2 2 2
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 		chk_rm_nr 0 1
 	fi
 }
@@ -3318,7 +3362,7 @@ userspace_tests()
 		sflags=backup speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 0
-		chk_prio_nr 0 0
+		chk_prio_nr 0 0 0 0
 	fi
 
 	# userspace pm type prevents rm_addr