lwt xmit hook does not expect positive return values in function ip_finish_output2 and ip6_finish_output2. However, BPF redirect programs can return positive values such like NET_XMIT_DROP, NET_RX_DROP, and etc as errors. Such return values can panic the kernel unexpectedly: https://gist.github.com/zhaiyan920/8fbac245b261fe316a7ef04c9b1eba48 This patch fixes the return values from BPF redirect, so the error handling would be consistent at xmit hook. It also adds a few test cases to prevent future regressions. v3: https://lore.kernel.org/bpf/cover.1690255889.git.yan@xxxxxxxxxxxxxx/ v2: https://lore.kernel.org/netdev/ZLdY6JkWRccunvu0@debian.debian/ v1: https://lore.kernel.org/bpf/ZLbYdpWC8zt9EJtq@debian.debian/ changes since v3: * minor change in commit message and changelogs * tested by Jakub Sitnicki changes since v2: * subject name changed * also covered redirect to ingress case * added selftests changes since v1: * minor code style changes Yan Zhai (2): bpf: fix skb_do_redirect return values bpf: selftests: add lwt redirect regression test cases include/linux/netdevice.h | 2 + net/core/filter.c | 9 +- tools/testing/selftests/bpf/Makefile | 1 + .../selftests/bpf/progs/test_lwt_redirect.c | 66 +++++++ .../selftests/bpf/test_lwt_redirect.sh | 174 ++++++++++++++++++ 5 files changed, 250 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_lwt_redirect.c create mode 100755 tools/testing/selftests/bpf/test_lwt_redirect.sh -- 2.30.2
