netdev - Re: [PATCH v15 bpf-next 17/18] net: xdp: introduce bpf_xdp

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Message-ID: <YWSD8O0lw6kaGmRD@lore-desk>
Date:   Mon, 11 Oct 2021 20:35:28 +0200
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        lorenzo.bianconi@...hat.com, davem@...emloft.net, ast@...nel.org,
        daniel@...earbox.net, shayagr@...zon.com, john.fastabend@...il.com,
        dsahern@...nel.org, brouer@...hat.com, echaudro@...hat.com,
        jasowang@...hat.com, alexander.duyck@...il.com, saeed@...nel.org,
        maciej.fijalkowski@...el.com, magnus.karlsson@...el.com,
        tirthendu.sarkar@...el.com, toke@...hat.com
Subject: Re: [PATCH v15 bpf-next 17/18] net: xdp: introduce bpf_xdp_pointer
 utility routine

> On Fri,  8 Oct 2021 14:49:55 +0200 Lorenzo Bianconi wrote:
> > +BPF_CALL_4(bpf_xdp_load_bytes, struct xdp_buff *, xdp, u32, offset,
> > +	   void *, buf, u32, len)
> > +{
> > +	void *ptr;
> > +
> > +	if (!buf)
> > +		return -EINVAL;
> 
> Can we make the verifier ensure it's not NULL?

I guess we can use ARG_PTR_TO_MEM instead of ARG_PTR_TO_UNINIT_MEM

> 
> > +	ptr = bpf_xdp_pointer(xdp, offset, len, buf);
> > +	if (ptr != buf)
> > +		memcpy(buf, ptr, len);
> 
> Don't we need to return an error in case offset + length > frame size?

ack, I will fix it.

Regards,
Lorenzo

> 
> > +	return 0;
> > +}

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