We're working on a user space control plane for the BPF sk_lookup hook [1]. The hook attaches to a network namespace and allows control over which socket receives a new connection / packet. I'm proposing to add a new getsockopt and a netns ioctl to retrieve netns cookies, which allows identifying which netns a socket belongs to. 1: https://www.kernel.org/doc/html/latest/bpf/prog_sk_lookup.html Changes in v3: - Use sock_net unconditionally - Fix unused variable in nsfs ioctl - Be strict about getsockopt value size Changes in v2: - Rebase on top of Eric Dumazet's netns cookie simplification Lorenz Bauer (4): net: add SO_NETNS_COOKIE socket option nsfs: add an ioctl to discover the network namespace cookie tools/testing: add test for NS_GET_COOKIE tools/testing: add a selftest for SO_NETNS_COOKIE arch/alpha/include/uapi/asm/socket.h | 2 + arch/mips/include/uapi/asm/socket.h | 2 + arch/parisc/include/uapi/asm/socket.h | 2 + arch/sparc/include/uapi/asm/socket.h | 2 + fs/nsfs.c | 7 +++ include/uapi/asm-generic/socket.h | 2 + include/uapi/linux/nsfs.h | 2 + net/core/sock.c | 7 +++ tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/Makefile | 2 +- tools/testing/selftests/net/config | 1 + tools/testing/selftests/net/so_netns_cookie.c | 61 +++++++++++++++++++ tools/testing/selftests/nsfs/.gitignore | 1 + tools/testing/selftests/nsfs/Makefile | 2 +- tools/testing/selftests/nsfs/config | 1 + tools/testing/selftests/nsfs/netns.c | 57 +++++++++++++++++ 16 files changed, 150 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/net/so_netns_cookie.c create mode 100644 tools/testing/selftests/nsfs/netns.c -- 2.27.0
