netdev - Re: [PATCH bpf-next] bpf, sockmap: Manual deletion of sockmap elements in user mode is not allowed

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: <87sfrky2bt.fsf@cloudflare.com>
Date:   Mon, 14 Mar 2022 16:30:30 +0100
From:   Jakub Sitnicki <jakub@...udflare.com>
To:     Wang Yufen <wangyufen@...wei.com>
Cc:     ast@...nel.org, john.fastabend@...il.com, daniel@...earbox.net,
        lmb@...udflare.com, davem@...emloft.net, kafai@...com,
        dsahern@...nel.org, kuba@...nel.org, songliubraving@...com,
        yhs@...com, kpsingh@...nel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next] bpf, sockmap: Manual deletion of sockmap
 elements in user mode is not allowed

On Mon, Mar 14, 2022 at 08:44 PM +08, Wang Yufen wrote:
> A tcp socket in a sockmap. If user invokes bpf_map_delete_elem to delete
> the sockmap element, the tcp socket will switch to use the TCP protocol
> stack to send and receive packets. The switching process may cause some
> issues, such as if some msgs exist in the ingress queue and are cleared
> by sk_psock_drop(), the packets are lost, and the tcp data is abnormal.
>
> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
> ---

Can you please tell us a bit more about the life-cycle of the socket in
your workload? Questions that come to mind:

1) What triggers the removal of the socket from sockmap in your case?

2) Would it still be a problem if removal from sockmap did not cause any
packets to get dropped?

[...]