netdev - Re: [PATCH bpf-next v2 4/5] bpf: Allow bpf_dynptr_from_skb() for tp

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Message-ID: <8ee6b7d3-71b7-4b66-aa49-26421d9c5b78@linux.dev>
Date: Thu, 5 Sep 2024 18:13:43 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Philo Lu <lulie@...ux.alibaba.com>
Cc: bpf@...r.kernel.org, edumazet@...gle.com, rostedt@...dmis.org,
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Subject: Re: [PATCH bpf-next v2 4/5] bpf: Allow bpf_dynptr_from_skb() for
 tp_btf

On 9/5/24 12:56 AM, Philo Lu wrote:
> Making tp_btf able to use bpf_dynptr_from_skb(), which is useful for skb
> parsing, especially for non-linear paged skb data. This is achieved by
> adding KF_TRUSTED_ARGS flag to bpf_dynptr_from_skb and registering it
> for TRACING progs. With KF_TRUSTED_ARGS, args from fentry/fexit are
> excluded, so that unsafe progs like fexit/__kfree_skb are not allowed.
> 
> We also need the skb dynptr to be read-only in tp_btf. Because
> may_access_direct_pkt_data() returns false by default when checking
> bpf_dynptr_from_skb, there is no need to add BPF_PROG_TYPE_TRACING to it
> explicitly.

Acked-by: Martin KaFai Lau <martin.lau@...nel.org>