netdev - Re: [PATCH net-next 6/9] net-timestamp: add tx OPT_ID

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: <6705804318fa1_1a41992941a@willemb.c.googlers.com.notmuch>
Date: Tue, 08 Oct 2024 14:56:03 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jason Xing <kerneljasonxing@...il.com>, 
 davem@...emloft.net, 
 edumazet@...gle.com, 
 kuba@...nel.org, 
 pabeni@...hat.com, 
 dsahern@...nel.org, 
 willemdebruijn.kernel@...il.com, 
 willemb@...gle.com, 
 ast@...nel.org, 
 daniel@...earbox.net, 
 andrii@...nel.org, 
 martin.lau@...ux.dev, 
 eddyz87@...il.com, 
 song@...nel.org, 
 yonghong.song@...ux.dev, 
 john.fastabend@...il.com, 
 kpsingh@...nel.org, 
 sdf@...ichev.me, 
 haoluo@...gle.com, 
 jolsa@...nel.org
Cc: bpf@...r.kernel.org, 
 netdev@...r.kernel.org, 
 Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 6/9] net-timestamp: add tx OPT_ID_TCP support for
 bpf case

Jason Xing wrote:
> From: Jason Xing <kernelxing@...cent.com>
> 
> We can set OPT_ID|OPT_ID_TCP before we initialize the last skb
> from each sendmsg. We only set the socket once like how we use
> setsockopt() with OPT_ID|OPT_ID_TCP flags.
> 
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> ---
>  net/core/skbuff.c | 16 +++++++++++++---
>  net/ipv4/tcp.c    | 19 +++++++++++++++----
>  2 files changed, 28 insertions(+), 7 deletions(-)
> 

> @@ -491,10 +491,21 @@ static u32 bpf_tcp_tx_timestamp(struct sock *sk)
>  	if (!(flags & SOF_TIMESTAMPING_TX_RECORD_MASK))
>  		return 0;
>  
> +	/* We require users to set both OPT_ID and OPT_ID_TCP flags
> +	 * together here, or else the key might be inaccurate.
> +	 */
> +	if (flags & SOF_TIMESTAMPING_OPT_ID &&
> +	    flags & SOF_TIMESTAMPING_OPT_ID_TCP &&
> +	    !(sk->sk_tsflags & (SOF_TIMESTAMPING_OPT_ID | SOF_TIMESTAMPING_OPT_ID_TCP))) {
> +		atomic_set(&sk->sk_tskey, (tcp_sk(sk)->write_seq - copied));
> +		sk->sk_tsflags |= (SOF_TIMESTAMPING_OPT_ID | SOF_TIMESTAMPING_OPT_ID_TCP);

So user and BPF admin conflict on both sk_tsflags and sktskey?

I think BPF resetting this key, or incrementing it, may break user
expectations.