linux-kernel - Re: [PATCH v4 1/2] net/tls: support maximum record size limit

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: <aNW0OxiN8M2hv7Qu@krikkit>
Date: Thu, 25 Sep 2025 23:29:31 +0200
From: Sabrina Dubroca <sd@...asysnail.net>
To: Wilfred Mallawa <wilfred.mallawa@....com>
Cc: "corbet@....net" <corbet@....net>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
	"john.fastabend@...il.com" <john.fastabend@...il.com>,
	"shuah@...nel.org" <shuah@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	"kuba@...nel.org" <kuba@...nel.org>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"horms@...nel.org" <horms@...nel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] net/tls: support maximum record size limit

2025-09-25, 05:39:14 +0000, Wilfred Mallawa wrote:
> On Wed, 2025-09-24 at 19:50 +0200, Sabrina Dubroca wrote:
> > > @@ -1111,6 +1180,11 @@ static int tls_get_info(struct sock *sk,
> > > struct sk_buff *skb, bool net_admin)
> > >  			goto nla_failure;
> > >  	}
> > >  
> > > +	err = nla_put_u16(skb, TLS_INFO_TX_RECORD_SIZE_LIM,
> > > +			  ctx->tx_record_size_limit);
> > 
> > I'm not sure here: if we do the +1 adjustment we'd be consistent with
> > the value reported by getsockopt, but OTOH users may get confused
> > about seeing a value larger than TLS_MAX_PAYLOAD_SIZE.
> Makes sense to keep the behaviour the same as getsockopt() right? So
> add the +1 changes here based on version (same as getsockopt()). In
> which case, it should never exceed TLS_MAX_PAYLOAD_SIZE.

The max value for 1.3 is TLS_MAX_PAYLOAD_SIZE+1 (after adjustment),
since it's the max value that will be accepted by setsockopt (after
passing the "value - 1 > TLS_MAX_PAYLOAD_SIZE" check). And it's the
value most users will see since it's the default.

-- 
Sabrina