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SubjectRe: [PATCH] bpf: Expose bpf_sk_storage_* to iterator programs
On Thu, Nov 12, 2020 at 09:09:14PM +0100, Florent Revest wrote:
> From: Florent Revest <revest@google.com>
>
> Iterators are currently used to expose kernel information to userspace
> over fast procfs-like files but iterators could also be used to
> initialize local storage. For example, the task_file iterator could be
> used to store associations between processes and sockets.
>
> This exposes the socket local storage helpers to all iterators. Martin
> Kafai checked that this was safe to call these helpers from the
> sk_storage_map iterators.
>
> Signed-off-by: Florent Revest <revest@google.com>
> ---
> kernel/trace/bpf_trace.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index e4515b0f62a8..3530120fa280 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -17,6 +17,8 @@
> #include <linux/error-injection.h>
> #include <linux/btf_ids.h>
>
> +#include <net/bpf_sk_storage.h>
> +
> #include <uapi/linux/bpf.h>
> #include <uapi/linux/btf.h>
>
> @@ -1750,6 +1752,14 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> NULL;
> case BPF_FUNC_d_path:
> return &bpf_d_path_proto;
> + case BPF_FUNC_sk_storage_get:
> + return prog->expected_attach_type == BPF_TRACE_ITER ?
> + &bpf_sk_storage_get_proto :
> + NULL;
> + case BPF_FUNC_sk_storage_delete:
> + return prog->expected_attach_type == BPF_TRACE_ITER ?
> + &bpf_sk_storage_delete_proto :
> + NULL;
Test(s) is needed. e.g. iterating a bpf_sk_storage_map and also
calling bpf_sk_storage_get/delete.

I would expect to see another test/example
showing how it works end-to-end to solve the problem you have in hand.
This patch probably belongs to a longer series.

BTW, I am also enabling bpf_sk_storage_(get|delete) for FENTRY/FEXIT/RAW_TP
but I think the conflict should be manageable.
https://patchwork.ozlabs.org/project/netdev/patch/20201112211313.2587383-1-kafai@fb.com/

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