netdev - Re: [RFC bpf-next v1 2/7] bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f35db6aa-ac4c-4690-bb54-4bbd5d4a3970@nvidia.com>
Date: Thu, 28 Aug 2025 16:43:55 +0300
From: Nimrod Oren <noren@...dia.com>
To: Amery Hung <ameryhung@...il.com>, bpf@...r.kernel.org
Cc: netdev@...r.kernel.org, alexei.starovoitov@...il.com, andrii@...nel.org,
 daniel@...earbox.net, kuba@...nel.org, martin.lau@...nel.org,
 mohsin.bashr@...il.com, saeedm@...dia.com, tariqt@...dia.com,
 mbloch@...dia.com, maciej.fijalkowski@...el.com, kernel-team@...a.com,
 Dragos Tatulea <dtatulea@...dia.com>, Gal Pressman <gal@...dia.com>
Subject: Re: [RFC bpf-next v1 2/7] bpf: Allow bpf_xdp_shrink_data to shrink a
 frag from head and tail

On 25/08/2025 22:39, Amery Hung wrote:
> Move skb_frag_t adjustment into bpf_xdp_shrink_data() and extend its
> functionality to be able to shrink an xdp fragment from both head and
> tail. In a later patch, bpf_xdp_pull_data() will reuse it to shrink an
> xdp fragment from head.
I had assumed that XDP multi-buffer frags must always be the same size,
except for the last one. If that’s the case, shrinking from the head
seems to break this rule.