On Fri, Feb 18, 2022 at 1:56 AM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> Set the cgroup path when a bpf prog is attached to a cgroup, and unset
> it when the bpf prog is detached.
>
> Below is the result after this change,
> $ cat progs.debug
> id name attached
> 5 dump_bpf_map bpf_iter_bpf_map
> 7 dump_bpf_prog bpf_iter_bpf_prog
> 17 bpf_sockmap cgroup:/
> 19 bpf_redir_proxy
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> ---
> kernel/bpf/cgroup.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> index 43eb3501721b..ebd87e54f2d0 100644
> --- a/kernel/bpf/cgroup.c
> +++ b/kernel/bpf/cgroup.c
> @@ -440,6 +440,7 @@ static int __cgroup_bpf_attach(struct cgroup *cgrp,
> struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
> struct bpf_cgroup_storage *new_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
> enum cgroup_bpf_attach_type atype;
> + char cgrp_path[64] = "cgroup:";
> struct bpf_prog_list *pl;
> struct list_head *progs;
> int err;
> @@ -508,6 +509,11 @@ static int __cgroup_bpf_attach(struct cgroup *cgrp,
> else
> static_branch_inc(&cgroup_bpf_enabled_key[atype]);
> bpf_cgroup_storages_link(new_storage, cgrp, type);
> +
> + cgroup_name(cgrp, cgrp_path + strlen("cgroup:"), 64);
> + cgrp_path[63] = '\0';
> + prog->aux->attach_name = kstrdup(cgrp_path, GFP_KERNEL);
> +
This is pure debug code. We cannot have it in the kernel.
Not even under #ifdef.
Please do such debug code on a side as your own bpf program.
For example by kprobe-ing in this function and keeping the path
in a bpf map or send it to user space via ringbuf.
Or enable cgroup tracepoint and monitor cgroup_mkdir with full path.
Record it in user space or in bpf map, etc.
Also please read Documentation/bpf/bpf_devel_QA.rst
bpf patches should be based on bpf-next tree.
These patches are not.
