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SubjectRe: [PATCH] Support for nlattr and nested_nlattr attribute search in EBPF filter
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On 1/23/20 2:08 PM, Kalimuthu Velappan wrote:
> Added attribute search and nested attribute support in EBPF filter
> functionality.

Your commit describes what the code does, but not the rationale why it's needed
resp. the use-case you're trying to solve with this.

Also, why it cannot be resolved in native BPF?

> Signed-off-by: Kalimuthu Velappan <kalimuthu.velappan@broadcom.com>
> ---
> include/uapi/linux/bpf.h | 5 ++++-
> net/core/filter.c | 22 ++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 4 +++-
> 3 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index dbbcf0b..ac9794c 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2938,7 +2938,10 @@ union bpf_attr {
> FN(probe_read_user), \
> FN(probe_read_kernel), \
> FN(probe_read_user_str), \
> - FN(probe_read_kernel_str),
> + FN(probe_read_kernel_str), \
> + FN(skb_get_nlattr), \
> + FN(skb_get_nlattr_nest),
> +

This is not on latest bpf-next tree.

> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 538f6a7..56a87e1 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -2699,6 +2699,24 @@ static const struct bpf_func_proto bpf_set_hash_invalid_proto = {
> .arg1_type = ARG_PTR_TO_CTX,
> };
>
> +static const struct bpf_func_proto bpf_skb_get_nlattr_proto = {
> + .func = bpf_skb_get_nlattr,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_ANYTHING,
> + .arg3_type = ARG_ANYTHING,
> +};
> +
> +static const struct bpf_func_proto skb_get_nlattr_nest_proto = {
> + .func = bpf_skb_get_nlattr_nest,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_ANYTHING,
> + .arg3_type = ARG_ANYTHING,
> +};
> +
> BPF_CALL_2(bpf_set_hash, struct sk_buff *, skb, u32, hash)

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