Seed a FAILED neighbor before triggering an unsolicited NA. Verify that
the entry transitions to STALE and learns the advertised link-layer
address only when drop_unsolicited_na is disabled, accept_untracked_na
mode 1 or in-prefix mode 2 is enabled, and IPv6 forwarding is enabled.
Verify that disabling each gate keeps the entry in FAILED without a
link-layer address.

Mark the seed externally learned and disable carrier-based eviction so
the entry cannot be garbage-collected before the NA arrives. Require the
marker after processing to prove that a recovered entry was updated in
place instead of deleted and recreated.

Keep the NA source, target, and neighbor key fixed for the mode 2 cases.
Vary the prefix configured on the router to exercise the source-prefix
check without changing the entry under test.

Arm packet capture before bringing up the host interface and starting
DAD. Wait for the capture to become ready and for tcpdump to exit so the
NA cannot be missed and receive processing is complete before checking
the neighbor entry.

Link: https://lore.kernel.org/r/[email protected]
Assisted-by: LLM Sashiko sparse
Signed-off-by: Lawrence Lee <[email protected]>
---
 .../net/ndisc_unsolicited_na_test.sh          | 195 ++++++++++++++----
 1 file changed, 160 insertions(+), 35 deletions(-)

diff --git a/tools/testing/selftests/net/ndisc_unsolicited_na_test.sh 
b/tools/testing/selftests/net/ndisc_unsolicited_na_test.sh
index 5db69dad0cfc..ba9e670b5149 100755
--- a/tools/testing/selftests/net/ndisc_unsolicited_na_test.sh
+++ b/tools/testing/selftests/net/ndisc_unsolicited_na_test.sh
@@ -3,12 +3,18 @@
 
 # This test is for the accept_untracked_na feature to
 # enable RFC9131 behaviour. The following is the test-matrix.
-# drop   accept  fwding                   behaviour
-# ----   ------  ------  ----------------------------------------------
-#    1        X       X  Don't update NC
-#    0        0       X  Don't update NC
-#    0        1       0  Don't update NC
-#    0        1       1  Add a STALE NC entry
+# state   drop   accept  fwding                   behaviour
+# ------  ----   ------  ------  ----------------------------------------------
+# absent     1        X       X  Don't update NC
+# absent     0        0       X  Don't update NC
+# absent     0        1       0  Don't update NC
+# absent     0        1       1  Add a STALE NC entry
+# failed     1        X       X  Keep the NC entry in FAILED state
+# failed     0        0       X  Keep the NC entry in FAILED state
+# failed     0        1       0  Keep the NC entry in FAILED state
+# failed     0        1       1  Update the NC entry to STALE
+# failed     0        2       1  Update the NC entry to STALE if in-network
+# failed     0        2       1  Keep the NC entry FAILED if out-of-network
 
 source lib.sh
 ret=0
@@ -19,14 +25,18 @@ PAUSE=no
 HOST_INTF="veth-host"
 ROUTER_INTF="veth-router"
 
-ROUTER_ADDR="2000:20::1"
+ROUTER_ADDR_IN_NETWORK="2000:20::1"
+ROUTER_ADDR_OUT_OF_NETWORK="2000:21::1"
+ROUTER_ADDR="${ROUTER_ADDR_IN_NETWORK}"
 HOST_ADDR="2000:20::2"
+HOST_LLADDR="02:00:00:00:00:02"
 SUBNET_WIDTH=64
 ROUTER_ADDR_WITH_MASK="${ROUTER_ADDR}/${SUBNET_WIDTH}"
 HOST_ADDR_WITH_MASK="${HOST_ADDR}/${SUBNET_WIDTH}"
 
 tcpdump_stdout=
 tcpdump_stderr=
+tcpdump_pid=
 
 log_test()
 {
@@ -75,6 +85,7 @@ setup()
 
        ${IP_ROUTER} link add ${ROUTER_INTF} type veth \
                 peer name ${HOST_INTF} netns ${HOST_NS}
+       ${IP_HOST} link set dev "${HOST_INTF}" address "${HOST_LLADDR}"
 
        # Enable IPv6 on both router and host, and configure static addresses.
        # The router here is the DUT
@@ -88,6 +99,8 @@ setup()
                 ${ROUTER_CONF}.drop_unsolicited_na=${drop_unsolicited_na}
        ${IP_ROUTER_EXEC} sysctl -qw \
                 ${ROUTER_CONF}.accept_untracked_na=${accept_untracked_na}
+       ${IP_ROUTER_EXEC} sysctl -qw \
+                ${ROUTER_CONF}.ndisc_evict_nocarrier=0
        ${IP_ROUTER_EXEC} sysctl -qw ${ROUTER_CONF}.disable_ipv6=0
        ${IP_ROUTER} addr add ${ROUTER_ADDR_WITH_MASK} dev ${ROUTER_INTF}
 
@@ -102,24 +115,39 @@ setup()
 }
 
 start_tcpdump() {
-       set -e
-       tcpdump_stdout=`mktemp`
-       tcpdump_stderr=`mktemp`
+       tcpdump_stdout=$(mktemp) || return 1
+       tcpdump_stderr=$(mktemp) || return 1
        ${IP_ROUTER_EXEC} timeout 15s \
                 tcpdump --immediate-mode -tpni ${ROUTER_INTF} -c 1 \
                 "icmp6 && icmp6[0] == 136 && src ${HOST_ADDR}" \
-                > ${tcpdump_stdout} 2> /dev/null
-       set +e
+                > "${tcpdump_stdout}" 2> "${tcpdump_stderr}" &
+       tcpdump_pid=$!
+
+       slowwait 5 grep -q "listening on ${ROUTER_INTF}" "${tcpdump_stderr}"
+}
+
+wait_tcpdump()
+{
+       local rc
+
+       wait "${tcpdump_pid}"
+       rc=$?
+       tcpdump_pid=
+
+       return "${rc}"
 }
 
 cleanup_tcpdump()
 {
-       set -e
-       [[ ! -z  ${tcpdump_stdout} ]] && rm -f ${tcpdump_stdout}
-       [[ ! -z  ${tcpdump_stderr} ]] && rm -f ${tcpdump_stderr}
+       if [ -n "${tcpdump_pid}" ]; then
+               kill "${tcpdump_pid}" 2> /dev/null
+               wait "${tcpdump_pid}" 2> /dev/null
+       fi
+       [ -n "${tcpdump_stdout}" ] && rm -f "${tcpdump_stdout}"
+       [ -n "${tcpdump_stderr}" ] && rm -f "${tcpdump_stderr}"
        tcpdump_stdout=
        tcpdump_stderr=
-       set +e
+       tcpdump_pid=
 }
 
 cleanup()
@@ -129,58 +157,145 @@ cleanup()
        ip netns del ${ROUTER_NS}
 }
 
-link_up() {
-       set -e
+router_link_up()
+{
        ${IP_ROUTER} link set dev ${ROUTER_INTF} up
+}
+
+host_link_up()
+{
        ${IP_HOST} link set dev ${HOST_INTF} up
-       set +e
 }
 
 verify_ndisc() {
        local drop_unsolicited_na=$1
        local accept_untracked_na=$2
        local forwarding=$3
+       local initial_state=${4:-absent}
+       local same_subnet=${5:-1}
+       local expected_lladdr
+       local neigh_show_output
+       local expected_state
+
+       if [ "${drop_unsolicited_na}" -eq 0 ] &&
+                       [ "${forwarding}" -eq 1 ]; then
+               case "${accept_untracked_na}" in
+               1)
+                       expected_state=STALE
+                       expected_lladdr="${HOST_LLADDR}"
+                       ;;
+               2)
+                       if [ "${same_subnet}" -eq 1 ]; then
+                               expected_state=STALE
+                               expected_lladdr="${HOST_LLADDR}"
+                       fi
+                       ;;
+               esac
+       fi
+       if [ -z "${expected_state}" ] &&
+                       [ "${initial_state}" = "failed" ]; then
+               expected_state=FAILED
+       fi
 
-       neigh_show_output=$(${IP_ROUTER} neigh show \
-                to ${HOST_ADDR} dev ${ROUTER_INTF} nud stale)
-       if [ ${drop_unsolicited_na} -eq 0 ] && \
-                       [ ${accept_untracked_na} -eq 1 ] && \
-                       [ ${forwarding} -eq 1 ]; then
-               # Neighbour entry expected to be present for 011 case
-               [[ ${neigh_show_output} ]]
+       if [ -n "${expected_state}" ]; then
+               neigh_show_output=$(${IP_ROUTER} neigh show \
+                       to "${HOST_ADDR}" dev "${ROUTER_INTF}")
+               if [[ " ${neigh_show_output} " != \
+                               *" ${expected_state} "* ]]; then
+                       return 1
+               fi
+               if [ -n "${expected_lladdr}" ] &&
+                               [[ " ${neigh_show_output} " != \
+                               *" lladdr ${expected_lladdr} "* ]]; then
+                       return 1
+               fi
+               if [[ "${expected_state}" == "FAILED" &&
+                     "${neigh_show_output}" == *"lladdr"* ]]; then
+                       return 1
+               fi
+               if [ "${initial_state}" = "failed" ]; then
+                       [[ "${neigh_show_output}" == *"extern_learn"* ]]
+               fi
        else
-               # Neighbour entry expected to be absent for all other cases
+               neigh_show_output=$(${IP_ROUTER} neigh show \
+                       to "${HOST_ADDR}" dev "${ROUTER_INTF}")
                [[ -z ${neigh_show_output} ]]
        fi
 }
 
 test_unsolicited_na_common()
 {
+       local same_subnet=${5:-1}
+       local neigh_show_output
+
+       if [ "${same_subnet}" -eq 1 ]; then
+               ROUTER_ADDR="${ROUTER_ADDR_IN_NETWORK}"
+       else
+               ROUTER_ADDR="${ROUTER_ADDR_OUT_OF_NETWORK}"
+       fi
+       ROUTER_ADDR_WITH_MASK="${ROUTER_ADDR}/${SUBNET_WIDTH}"
+
        # Setup the test bed, but keep links down
-       setup $1 $2 $3
+       setup "$1" "$2" "$3"
+
+       if [ "${4:-absent}" = "failed" ]; then
+               if ! ${IP_ROUTER} neigh replace "${HOST_ADDR}" \
+                               dev "${ROUTER_INTF}" \
+                               nud failed extern_learn; then
+                       echo "Unable to create NUD_FAILED neighbor entry"
+                       return 1
+               fi
+               neigh_show_output=$(${IP_ROUTER} neigh show \
+                       to "${HOST_ADDR}" dev "${ROUTER_INTF}")
+               if [[ " ${neigh_show_output} " != *" FAILED "* ]]; then
+                       echo "Unable to verify NUD_FAILED neighbor entry"
+                       return 1
+               fi
+               if [[ "${neigh_show_output}" != *"extern_learn"* ]]; then
+                       echo "Neighbor entry is not externally learned"
+                       return 1
+               fi
+       fi
 
-       # Bring the link up, wait for the NA,
-       # and add a delay to ensure neighbour processing is done.
-       link_up
-       start_tcpdump
+       # Arm the capture before bringing up the host and starting DAD.
+       router_link_up || return 1
+       start_tcpdump || return 1
+       host_link_up || return 1
+
+       # Closing tcpdump's packet socket calls synchronize_net(), so waiting
+       # for it also waits for receive processing of the captured NA.
+       wait_tcpdump || return 1
 
        # Verify the neighbour table
-       verify_ndisc $1 $2 $3
+       verify_ndisc "$1" "$2" "$3" "$4" "${same_subnet}"
 
 }
 
 test_unsolicited_na_combination() {
-       test_unsolicited_na_common $1 $2 $3
+       local initial_state=${4:-absent}
+       local same_subnet=${5:-1}
+       local rc
+
+       test_unsolicited_na_common "$1" "$2" "$3" "${initial_state}" \
+               "${same_subnet}"
+       rc=$?
        test_msg=("test_unsolicited_na: "
                "drop_unsolicited_na=$1 "
                "accept_untracked_na=$2 "
                "forwarding=$3")
-       log_test $? 0 "${test_msg[*]}"
+       if [ "${initial_state}" = "failed" ]; then
+               test_msg+=("initial_state=failed")
+       fi
+       if [ "$2" -eq 2 ]; then
+               test_msg+=("same_subnet=${same_subnet}")
+       fi
+       log_test "${rc}" 0 "${test_msg[*]}"
        cleanup
 }
 
 test_unsolicited_na_combinations() {
        # Args: drop_unsolicited_na accept_untracked_na forwarding
+       #       [initial_state] [same_subnet]
 
        # Expect entry
        test_unsolicited_na_combination 0 1 1
@@ -193,6 +308,16 @@ test_unsolicited_na_combinations() {
        test_unsolicited_na_combination 1 0 1
        test_unsolicited_na_combination 1 1 0
        test_unsolicited_na_combination 1 1 1
+
+       # Expect FAILED entry to become STALE
+       test_unsolicited_na_combination 0 1 1 failed
+       test_unsolicited_na_combination 0 2 1 failed 1
+
+       # Expect FAILED entry to remain FAILED
+       test_unsolicited_na_combination 0 0 1 failed
+       test_unsolicited_na_combination 0 1 0 failed
+       test_unsolicited_na_combination 1 1 1 failed
+       test_unsolicited_na_combination 0 2 1 failed 0
 }
 
 ###############################################################################
-- 
2.43.0


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