From: Daniel Lakeland <dlakelan@street-artists.org>
To: David Ahern <dsahern@gmail.com>,
Stephen Hemminger <stephen@networkplumber.org>
Cc: netdev@vger.kernel.org
Subject: Re: BUG REPORT: iproute2 seems to have bug with dsfield/tos in ip-rule and ip-route
Date: Wed, 13 Dec 2017 14:52:43 -0800 [thread overview]
Message-ID: <a745127e-58f6-47e6-7b44-a1b5e028bd2d@street-artists.org> (raw)
In-Reply-To: <224860aa-17a8-37a1-cbfe-66899c1bba94@gmail.com>
On 12/13/2017 02:40 PM, David Ahern wrote:
>
> In fib4_rule_configure, this the check that is failing:
>
> if (frh->tos & ~IPTOS_TOS_MASK)
> goto errout;
>
> and EINVAL is returned.
>
> IPv4 routes has not checking on tos -- it is passed from user and
> rtm_tos to fc_tos to fib alias tos.
it seems to me that this IPTOS_TOS_MASK check should be either gotten
rid of, or equal to 0x03 in modern usage. The bottom 2 bits are ECN and
I suppose someone might want to route based on congestion... and hence
maybe the mask should be dropped entirely, but if you refuse to allow
routes on ECN then you'd want 0x03 as the mask
it seems to me this is left over from before DSCP.
apparently most people don't route on DSCP or work around this with
firewall marks, and so this doesn't cause trouble enough to have been
reported before?
I think the follow up question is does anyone have any idea why someone
who set up routes with dsfield settings is not seeing packets routed?
The kernel may not handle ip rule with DSCP, but it takes
ip route add default dsfield CS6 dev veth0
just fine... and shows up in the route table, but for example the person
is not seeing CS6 marked packets going to veth2 and instead is seeing
them routed to veth0 the default route...
next prev parent reply other threads:[~2017-12-13 22:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-13 17:40 BUG REPORT: iproute2 seems to have bug with dsfield/tos in ip-rule and ip-route Daniel Lakeland
2017-12-13 18:12 ` Stephen Hemminger
2017-12-13 18:33 ` Daniel Lakeland
2017-12-13 19:05 ` Daniel Lakeland
2017-12-13 22:40 ` David Ahern
2017-12-13 22:52 ` Daniel Lakeland [this message]
2017-12-13 23:05 ` David Ahern
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