On 29/05/2024 14:10, Kenta Tada wrote:
> When CONFIG_NETKIT=y,
> bpftool-cgroup shows error even if the cgroup's path is correct:
>
> $ bpftool cgroup tree /sys/fs/cgroup
> CgroupPath
> ID AttachType AttachFlags Name
> Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address
>
> From strace and kernel tracing, I found netkit returned ENXIO and this command failed.
> I think this AttachType(BPF_NETKIT_PRIMARY) is not relevant to cgroup.
>
> bpftool-cgroup should query just only cgroup-related attach types.
>
> Signed-off-by: Kenta Tada <tadakentaso@xxxxxxxxx>
> ---
> tools/bpf/bpftool/cgroup.c | 47 +++++++++++++++++++++++++++++++++-----
> 1 file changed, 41 insertions(+), 6 deletions(-)
>
> diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
> index af6898c0f388..bb2703aa4756 100644
> --- a/tools/bpf/bpftool/cgroup.c
> +++ b/tools/bpf/bpftool/cgroup.c
> @@ -19,6 +19,39 @@
>
> #include "main.h"
>
> +static const bool cgroup_attach_types[] = {
> + [BPF_CGROUP_INET_INGRESS] = true,
> + [BPF_CGROUP_INET_EGRESS] = true,
> + [BPF_CGROUP_INET_SOCK_CREATE] = true,
> + [BPF_CGROUP_INET_SOCK_RELEASE] = true,
> + [BPF_CGROUP_INET4_BIND] = true,
> + [BPF_CGROUP_INET6_BIND] = true,
> + [BPF_CGROUP_INET4_POST_BIND] = true,
> + [BPF_CGROUP_INET6_POST_BIND] = true,
> + [BPF_CGROUP_INET4_CONNECT] = true,
> + [BPF_CGROUP_INET6_CONNECT] = true,
> + [BPF_CGROUP_UNIX_CONNECT] = true,
> + [BPF_CGROUP_INET4_GETPEERNAME] = true,
> + [BPF_CGROUP_INET6_GETPEERNAME] = true,
> + [BPF_CGROUP_UNIX_GETPEERNAME] = true,
> + [BPF_CGROUP_INET4_GETSOCKNAME] = true,
> + [BPF_CGROUP_INET6_GETSOCKNAME] = true,
> + [BPF_CGROUP_UNIX_GETSOCKNAME] = true,
> + [BPF_CGROUP_UDP4_SENDMSG] = true,
> + [BPF_CGROUP_UDP6_SENDMSG] = true,
> + [BPF_CGROUP_UNIX_SENDMSG] = true,
> + [BPF_CGROUP_UDP4_RECVMSG] = true,
> + [BPF_CGROUP_UDP6_RECVMSG] = true,
> + [BPF_CGROUP_UNIX_RECVMSG] = true,
> + [BPF_CGROUP_SOCK_OPS] = true,
> + [BPF_CGROUP_DEVICE] = true,
> + [BPF_CGROUP_SYSCTL] = true,
> + [BPF_CGROUP_GETSOCKOPT] = true,
> + [BPF_CGROUP_SETSOCKOPT] = true,
> + [BPF_LSM_CGROUP] = true,
> + [__MAX_BPF_ATTACH_TYPE] = false,
> +};
Thanks for this!
I can't say I'm glad to see another version of the list of
cgroup-related attach types (in addition to HELP_SPEC_ATTACH_TYPES and
to the manual page). But the alternative would be to explicitly skip
BPF_NETKIT_PRIMARY, which is not great, either. Too bad we don't have a
way to check whether the type is cgroup-related in libbpf or from the
bpf.h headers; but I don't think there's much interest to add it there,
so we'll probably have the array. We should account for it in
tools/testing/selftests/bpf/test_bpftool_synctypes.py, but I can do this
as a follow-up if you don't feel like messing up with the Python script.
> +
> #define HELP_SPEC_ATTACH_FLAGS \
> "ATTACH_FLAGS := { multi | override }"
>
> @@ -187,14 +220,16 @@ static int cgroup_has_attached_progs(int cgroup_fd)
> bool no_prog = true;
>
> for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {
> - int count = count_attached_bpf_progs(cgroup_fd, type);
> + if (cgroup_attach_types[type]) {
Please change here:
int count;
if (!cgroup_attach_types[type])
continue;
And no need to further indent the rest of the block.
> + int count = count_attached_bpf_progs(cgroup_fd, type);
>
> - if (count < 0 && errno != EINVAL)
> - return -1;
> + if (count < 0 && errno != EINVAL)
> + return -1;
>
> - if (count > 0) {
> - no_prog = false;
> - break;
> + if (count > 0) {
> + no_prog = false;
> + break;
> + }
> }
> }
>
