On 10/11, Alexei Starovoitov wrote:
> On Fri, Oct 11, 2019 at 9:21 AM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
> >
> > Even though we have the pointer to user_struct and can recover
> > uid of the user who has created the program, it usually contains
> > 0 (root) which is not very informative. Let's store the comm of the
> > calling process and export it via bpf_prog_info. This should help
> > answer the question "which process loaded this particular program".
> >
> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> > ---
> > include/linux/bpf.h | 1 +
> > include/uapi/linux/bpf.h | 2 ++
> > kernel/bpf/syscall.c | 4 ++++
> > 3 files changed, 7 insertions(+)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 5b9d22338606..b03ea396afe5 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -421,6 +421,7 @@ struct bpf_prog_aux {
> > struct work_struct work;
> > struct rcu_head rcu;
> > };
> > + char created_by_comm[BPF_CREATED_COMM_LEN];
> > };
> >
> > struct bpf_array {
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index a65c3b0c6935..4e883ecbba1e 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -326,6 +326,7 @@ enum bpf_attach_type {
> > #define BPF_F_NUMA_NODE (1U << 2)
> >
> > #define BPF_OBJ_NAME_LEN 16U
> > +#define BPF_CREATED_COMM_LEN 16U
>
> Nack.
> 16 bytes is going to be useless.
> We found it the hard way with prog_name.
> If you want to embed additional debug information
> please use BTF for that.
BTF was my natural choice initially, but then I saw created_by_uid and
thought created_by_comm might have a chance :-)
To clarify, by BTF you mean creating some unused global variable
and use its name as the debugging info? Or there is some better way?
