[PATCH net-next v2 6/6] selftests/vsock: test the netns assign privilege checks
From: Bobby Eshleman <hidden>
Date: 2026-09-22 01:18:39
Also in:
kvm, linux-doc, linux-kselftest, lkml, virtualization
Subsystem:
kernel selftest framework, the rest, vm sockets (af_vsock) · Maintainers:
Shuah Khan, Shuah Khan, Linus Torvalds, Stefano Garzarella
From: Bobby Eshleman <redacted> VSOCK_CMD_DEV_NETNS_SET refuses callers without CAP_NET_ADMIN in the init user namespace. Add two tests: one confirms that CAP_NET_ADMIN is required even by a privileged user and the other confirms that CAP_NET_ADMIN in an unprivileged user ns alone is insufficient. CONFIG_USER_NS is needed to test the CAP_NET_ADMIN + unprivileged user ns case. Signed-off-by: Bobby Eshleman <redacted> --- Changes in v2: - Assert only that the command fails, not EPERM: ynl's cli.py does not report the errno (Sashiko) - Use ynl cli.py for the assign --- tools/testing/selftests/vsock/config | 1 + tools/testing/selftests/vsock/vmtest.sh | 54 ++++++++++++++++++++++++++++++++- 2 files changed, 54 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vsock/config b/tools/testing/selftests/vsock/config
index 5f0a4f17dfc9..4b31085558fa 100644
--- a/tools/testing/selftests/vsock/config
+++ b/tools/testing/selftests/vsock/config@@ -109,3 +109,4 @@ CONFIG_FS_DAX=y CONFIG_MEMORY_HOTPLUG=y CONFIG_MEMORY_HOTREMOVE=y CONFIG_ZONE_DEVICE=y +CONFIG_USER_NS=y
diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index e94cc2fd90cc..4f42bcdac3f6 100755
--- a/tools/testing/selftests/vsock/vmtest.sh
+++ b/tools/testing/selftests/vsock/vmtest.sh@@ -81,6 +81,8 @@ readonly TEST_NAMES=( ns_guest_assign_g2h_netns_host_connect_ok ns_guest_assign_g2h_netns_reset_on_ns_delete_ok ns_guest_assign_g2h_netns_old_conn_send_fails + ns_guest_assign_g2h_netns_no_cap_net_admin_fails + ns_guest_assign_g2h_netns_unpriv_user_ns_fails ) readonly TEST_DESCS=( # vm_server_host_client
@@ -175,6 +177,12 @@ readonly TEST_DESCS=( # ns_guest_assign_g2h_netns_old_conn_send_fails "Check connections made before the assign stop sending once they lose the device." + + # ns_guest_assign_g2h_netns_no_cap_net_admin_fails + "Check assigning the guest's vsock device to a namespace needs CAP_NET_ADMIN." + + # ns_guest_assign_g2h_netns_unpriv_user_ns_fails + "Check an unprivileged user cannot claim the guest's vsock device via a user ns." ) readonly USE_SHARED_VM=(
@@ -187,6 +195,8 @@ readonly USE_SHARED_VM=( ns_guest_assign_g2h_netns_host_connect_ok ns_guest_assign_g2h_netns_reset_on_ns_delete_ok ns_guest_assign_g2h_netns_old_conn_send_fails + ns_guest_assign_g2h_netns_no_cap_net_admin_fails + ns_guest_assign_g2h_netns_unpriv_user_ns_fails ) readonly NS_MODES=("local" "global")
@@ -335,7 +345,7 @@ check_args() { check_deps() { for dep in vng ${QEMU} busybox pkill ssh ss socat nsenter unshare \ - python3; do + setpriv python3; do if [[ ! -x $(command -v "${dep}") ]]; then echo -e "skip: dependency ${dep} not found!\n" exit "${KSFT_SKIP}"
@@ -1832,6 +1842,48 @@ test_ns_guest_assign_g2h_netns_reset_on_ns_delete_ok() { return "${KSFT_PASS}" } +test_ns_guest_assign_g2h_netns_no_cap_net_admin_fails() { + local cmd="unshare -n setpriv --bounding-set=-net_admin" + local rc + + vm_ssh "init_ns" -- "${cmd}" python3 /root/ynl/cli.py --no-schema \ + --spec /root/ynl/vsock.yaml --do dev-netns-set &>/dev/null + rc=$? + + if [[ "${rc}" -eq 0 ]]; then + log_host "assign unexpectedly succeeded without CAP_NET_ADMIN" + return "${KSFT_FAIL}" + fi + + return "${KSFT_PASS}" +} + +test_ns_guest_assign_g2h_netns_unpriv_user_ns_fails() { + local unpriv_uid=65534 + local unpriv + local rc + + unpriv="setpriv --reuid=${unpriv_uid} --regid=${unpriv_uid}" + unpriv="${unpriv} --clear-groups" + + if ! vm_ssh "init_ns" -- "${unpriv} unshare -U true"; then + log_host "unprivileged user namespaces unavailable, skipping" + return "${KSFT_SKIP}" + fi + + vm_ssh "init_ns" -- "${unpriv} unshare -Urn" \ + python3 /root/ynl/cli.py --no-schema \ + --spec /root/ynl/vsock.yaml --do dev-netns-set &>/dev/null + rc=$? + + if [[ "${rc}" -eq 0 ]]; then + log_host "assign unexpectedly succeeded for unprivileged user" + return "${KSFT_FAIL}" + fi + + return "${KSFT_PASS}" +} + shared_vm_test() { local tname
--
2.53.0-Meta