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

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Message-ID: <35405b07-76db-1d34-fdf2-9066ad21d142@huaweicloud.com>
Date:   Wed, 21 Sep 2022 10:41:10 +0800
From:   Pu Lehui <pulehui@...weicloud.com>
To:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Quentin Monnet <quentin@...valent.com>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Pu Lehui <pulehui@...wei.com>
Subject: Re: [PATCH bpf v4 0/2] Fix wrong cgroup attach flags being assigned
 to effective progs



On 2022/9/20 23:42, Pu Lehui wrote:
> From: Pu Lehui <pulehui@...wei.com>
> 
> 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@huaweicloud.com
> - Don't show attach flags when effective query. (John, sdf, Martin)
> 
> v2:
> https://lore.kernel.org/bpf/20220908145304.3436139-1-pulehui@huaweicloud.com
> - Limit prog_cnt to avoid overflow. (John)
> - Add more detail message.
> 
> v1:
> https://lore.kernel.org/bpf/20220820120234.2121044-1-pulehui@huawei.com
> 
> 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