From: "Theo de Raadt" <deraadt@openbsd.org>
Subject: Re: chromium: disable IP_TOS for UDP
To: robert@openbsd.org, ports@openbsd.org
Date: Wed, 09 Sep 2026 22:19:49 -0600

We need to do something, or chrome will keep doing these coredumps.

> Kirill A. Korinsky <kirill@korins.ky> wrote:
> 
> > Seems that new chromium plays with TOS at UDP for HTTP/3 and our pledge
> > prevents it, and kills the process. It dumps ~100Mb core and after that it
> > fallback to HTTP/1.1.
> 
> We are encountering this too many places, so I'd like everyone to consider
> this 2-step approach, becuase Linux dual-stack has utterly poisoned the
> ecosystem and noone looks at setsockopt return values accurately.
> 
> 1. netinet6 accepts IPPROTO_IP/IP_TOS and converts it to IPPROTO_IPV6/IPV6_TCLASS
> 
> 2. For programs which are pledged, allow that through
> 
> Index: netinet6/ip6_output.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/ip6_output.c,v
> diff -u -p -u -r1.308 ip6_output.c
> --- netinet6/ip6_output.c	5 Aug 2026 09:43:19 -0000	1.308
> +++ netinet6/ip6_output.c	8 Sep 2026 23:53:46 -0000
> @@ -1032,6 +1032,12 @@ ip6_ctloutput(int op, struct socket *so,
>  	privileged = (inp->inp_socket->so_state & SS_PRIV);
>  	uproto = (int)so->so_proto->pr_protocol;
>  
> +	/* Linux poisoned the ecosystem */
> +	if (level == IPPROTO_IP && optname == IP_TOS) {
> +		level = IPPROTO_IPV6;
> +		optname = IPV6_TCLASS;
> +	}
> +
>  	if (level != IPPROTO_IPV6)
>  		return (EINVAL);
>  
> 
> Index: kern/kern_pledge.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_pledge.c,v
> diff -u -p -u -r1.365 kern_pledge.c
> --- kern/kern_pledge.c	4 Sep 2026 02:38:28 -0000	1.365
> +++ kern/kern_pledge.c	8 Sep 2026 23:37:52 -0000
> @@ -1451,9 +1464,17 @@ pledge_sockopt(struct proc *p, int set, 
>  		}
>  		break;
>  	case AF_INET6:
> -		if (level == IPPROTO_IPV6) {
> +		switch (level) {
> +		case IPPROTO_IPV6:
>  			switch (optname) {
>  			case IPV6_TCLASS:
> +				return (0);
> +			}
> +			break;
> +		/* Because Linux makes the universe stink */
> +		case IPPROTO_IP:
> +			switch (optname) {
> +			case IP_TOS:
>  				return (0);
>  			}
>  		}
>