Re: [PATCH bpf v4 0/2] Fix wrong cgroup attach flags being assigned to effective progs

[Pu Lehui]

On 2022/9/20 23:42, Pu Lehui wrote:
> From: Pu Lehui <pulehui@xxxxxxxxxx>
>
> When root-cgroup attach multi progs and sub-cgroup attach a
> override prog, bpftool will display incorrectly for the attach
> flags of the sub-cgroup’s effective progs:
>
> $ bpftool cgroup tree /sys/fs/cgroup effective
> CgroupPath
> ID       AttachType      AttachFlags     Name
> /sys/fs/cgroup
> 6        cgroup_sysctl   multi           sysctl_tcp_mem
> 13       cgroup_sysctl   multi           sysctl_tcp_mem
> /sys/fs/cgroup/cg1
> 20       cgroup_sysctl   override        sysctl_tcp_mem
> 6        cgroup_sysctl   override        sysctl_tcp_mem <- wrong
> 13       cgroup_sysctl   override        sysctl_tcp_mem <- wrong
> /sys/fs/cgroup/cg1/cg2
> 20       cgroup_sysctl                   sysctl_tcp_mem
> 6        cgroup_sysctl                   sysctl_tcp_mem
> 13       cgroup_sysctl                   sysctl_tcp_mem
>
> For cg1, obviously, the attach flags of prog6 and prog13 can not be
> OVERRIDE. And for query with EFFECTIVE flags, exporting attach flags
> does not make sense. So let's remove the AttachFlags field and the
> associated logic. After these patches, the above effective cgroup
> tree will show as bellow:
>
> # bpftool cgroup tree /sys/fs/cgroup effective
> CgroupPath
> ID       AttachType      Name
> /sys/fs/cgroup
> 6        cgroup_sysctl   sysctl_tcp_mem
> 13       cgroup_sysctl   sysctl_tcp_mem
> /sys/fs/cgroup/cg1
> 20       cgroup_sysctl   sysctl_tcp_mem
> 6        cgroup_sysctl   sysctl_tcp_mem
> 13       cgroup_sysctl   sysctl_tcp_mem
> /sys/fs/cgroup/cg1/cg2
> 20       cgroup_sysctl   sysctl_tcp_mem
> 6        cgroup_sysctl   sysctl_tcp_mem
> 13       cgroup_sysctl   sysctl_tcp_mem
>
> v4:
> - Reject prog_attach_flags array when effective query. (Martin)
> - Target to bpf tree. (Martin)
>
> v3:
> https://lore.kernel.org/bpf/20220914161742.3180731-1-pulehui@xxxxxxxxxxxxxxx
> - Don't show attach flags when effective query. (John, sdf, Martin)
>
> v2:
> https://lore.kernel.org/bpf/20220908145304.3436139-1-pulehui@xxxxxxxxxxxxxxx
> - Limit prog_cnt to avoid overflow. (John)
> - Add more detail message.
>
> v1:
> https://lore.kernel.org/bpf/20220820120234.2121044-1-pulehui@xxxxxxxxxx
>
> Pu Lehui (2):
>    bpf, cgroup: Reject prog_attach_flags array when effective query
>    bpftool: Fix wrong cgroup attach flags being assigned to effective
>      progs
>
>   include/uapi/linux/bpf.h       |  7 +++--
>   kernel/bpf/cgroup.c            | 28 +++++++++++-------
>   tools/bpf/bpftool/cgroup.c     | 54 ++++++++++++++++++++++++++++++----
>   tools/include/uapi/linux/bpf.h |  7 +++--
>   4 files changed, 77 insertions(+), 19 deletions(-)

selftest no pass, sorry, will fix.
https://github.com/kernel-patches/bpf/actions/runs/3088351905/jobs/4995009382