linux-kernel - Re: [PATCH v12 net-next 06/23] net/tcp: Add TCP-AO sign to outgoing packets

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Message-ID: <c2c0b0684b9c2a930ae6001bcc0044dd7a0862d5.camel@redhat.com>
Date:   Thu, 21 Sep 2023 13:23:59 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Dmitry Safonov <dima@...sta.com>, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        Dan Carpenter <error27@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Donald Cassidy <dcassidy@...hat.com>,
        Eric Biggers <ebiggers@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Francesco Ruggeri <fruggeri05@...il.com>,
        "Gaillardetz, Dominik" <dgaillar@...na.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Ivan Delalande <colona@...sta.com>,
        Leonard Crestez <cdleonard@...il.com>,
        "Nassiri, Mohammad" <mnassiri@...na.com>,
        Salam Noureddine <noureddine@...sta.com>,
        Simon Horman <simon.horman@...igine.com>,
        "Tetreault, Francois" <ftetreau@...na.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v12 net-next 06/23] net/tcp: Add TCP-AO sign to outgoing
 packets

On Mon, 2023-09-18 at 20:00 +0100, Dmitry Safonov wrote:
> @@ -1361,16 +1385,48 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
>  		th->window	= htons(min(tp->rcv_wnd, 65535U));
>  	}
>  
> -	tcp_options_write(th, tp, &opts);
> +	tcp_options_write(th, tp, &opts, &key);
>  
> +	if (tcp_key_is_md5(&key)) {
>  #ifdef CONFIG_TCP_MD5SIG
> -	/* Calculate the MD5 hash, as we have all we need now */
> -	if (md5) {
> +		/* Calculate the MD5 hash, as we have all we need now */
>  		sk_gso_disable(sk);
>  		tp->af_specific->calc_md5_hash(opts.hash_location,
> -					       md5, sk, skb);
> -	}
> +					       key.md5_key, sk, skb);
>  #endif
> +	} else if (tcp_key_is_ao(&key)) {
> +#ifdef CONFIG_TCP_AO
> +		struct tcp_ao_info *ao;
> +		void *tkey_buf = NULL;
> +		u8 *traffic_key;
> +		__be32 disn;
> +
> +		ao = rcu_dereference_protected(tcp_sk(sk)->ao_info,
> +					       lockdep_sock_is_held(sk));
> +		if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) {
> +			if (tcb->tcp_flags & TCPHDR_ACK)
> +				disn = ao->risn;
> +			else
> +				disn = 0;
> +
> +			tkey_buf = kmalloc(tcp_ao_digest_size(key.ao_key),
> +					   GFP_ATOMIC);
> +			if (!tkey_buf) {
> +				kfree_skb_reason(skb, SKB_DROP_REASON_NOMEM);
> +				return -ENOMEM;
> +			}
> +			traffic_key = tkey_buf;
> +			tp->af_specific->ao_calc_key_sk(key.ao_key, traffic_key,
> +							sk, ao->lisn, disn, true);
> +		} else {
> +			traffic_key = snd_other_key(key.ao_key);
> +		}
> +		tp->af_specific->calc_ao_hash(opts.hash_location, key.ao_key,
> +					      sk, skb, traffic_key,
> +					      opts.hash_location - (u8 *)th, 0);
> +		kfree(tkey_buf);
> +#endif

I'm sorry for the incremental feedback.

The above could possibly deserve being moved to a specific helper, for
both readability and code locality when TCP_AO is enabled at compile
time but not used.

Cheers,

Paolo