Merge branch 'unmask-upper-dscp-bits-part-1'

Ido Schimmel says:

====================
Unmask upper DSCP bits - part 1

tl;dr - This patchset starts to unmask the upper DSCP bits in the IPv4
flow key in preparation for allowing IPv4 FIB rules to match on DSCP.
No functional changes are expected.

The TOS field in the IPv4 flow key ('flowi4_tos') is used during FIB
lookup to match against the TOS selector in FIB rules and routes.

It is currently impossible for user space to configure FIB rules that
match on the DSCP value as the upper DSCP bits are either masked in the
various call sites that initialize the IPv4 flow key or along the path
to the FIB core.

In preparation for adding a DSCP selector to IPv4 and IPv6 FIB rules, we
need to make sure the entire DSCP value is present in the IPv4 flow key.
This patchset starts to unmask the upper DSCP bits in the various places
that invoke the core FIB lookup functions directly (patches #1-#7) and
in the input route path (patches #8-#12). Future patchsets will do the
same in the output route path.

No functional changes are expected as commit 1fa3314c14c6 ("ipv4:
Centralize TOS matching") moved the masking of the upper DSCP bits to
the core where 'flowi4_tos' is matched against the TOS selector.
====================

Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/core/filter.c

···
 #include <net/netkit.h>
 #include <linux/un.h>
 #include <net/xdp_sock_drv.h>
+#include <net/inet_dscp.h>
 
 #include "dev.h"
 
···
 		fl4.flowi4_iif = params->ifindex;
 		fl4.flowi4_oif = 0;
 	}
-	fl4.flowi4_tos = params->tos & IPTOS_RT_MASK;
+	fl4.flowi4_tos = params->tos & INET_DSCP_MASK;
 	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
 	fl4.flowi4_flags = 0;
 

net/ipv4/fib_frontend.c

···
 			.flowi4_iif = LOOPBACK_IFINDEX,
 			.flowi4_l3mdev = l3mdev_master_ifindex_rcu(dev),
 			.daddr = ip_hdr(skb)->saddr,
-			.flowi4_tos = ip_hdr(skb)->tos & IPTOS_RT_MASK,
+			.flowi4_tos = ip_hdr(skb)->tos & INET_DSCP_MASK,
 			.flowi4_scope = scope,
 			.flowi4_mark = vmark ? skb->mark : 0,
 		};
···
 	struct flowi4           fl4 = {
 		.flowi4_mark = frn->fl_mark,
 		.daddr = frn->fl_addr,
-		.flowi4_tos = frn->fl_tos & IPTOS_RT_MASK,
+		.flowi4_tos = frn->fl_tos & INET_DSCP_MASK,
 		.flowi4_scope = frn->fl_scope,
 	};
 	struct fib_table *tb;

net/ipv4/icmp.c

···
 		orefdst = skb_in->_skb_refdst; /* save old refdst */
 		skb_dst_set(skb_in, NULL);
 		err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
-				     RT_TOS(tos), rt2->dst.dev);
+				     tos, rt2->dst.dev);
 
 		dst_release(&rt2->dst);
 		rt2 = skb_rtable(skb_in);

net/ipv4/ipmr.c

···
 #include <net/fib_rules.h>
 #include <linux/netconf.h>
 #include <net/rtnh.h>
+#include <net/inet_dscp.h>
 
 #include <linux/nospec.h>
 
···
 	struct flowi4 fl4 = {
 		.daddr = iph->daddr,
 		.saddr = iph->saddr,
-		.flowi4_tos = RT_TOS(iph->tos),
+		.flowi4_tos = iph->tos & INET_DSCP_MASK,
 		.flowi4_oif = (rt_is_output_route(rt) ?
 			       skb->dev->ifindex : 0),
 		.flowi4_iif = (rt_is_output_route(rt) ?

net/ipv4/netfilter/ipt_rpfilter.c

···
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
+#include <net/inet_dscp.h>
 #include <linux/ip.h>
 #include <net/ip.h>
 #include <net/ip_fib.h>
···
 	flow.daddr = iph->saddr;
 	flow.saddr = rpfilter_get_saddr(iph->daddr);
 	flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
-	flow.flowi4_tos = iph->tos & IPTOS_RT_MASK;
+	flow.flowi4_tos = iph->tos & INET_DSCP_MASK;
 	flow.flowi4_scope = RT_SCOPE_UNIVERSE;
 	flow.flowi4_l3mdev = l3mdev_master_ifindex_rcu(xt_in(par));
 	flow.flowi4_uid = sock_net_uid(xt_net(par), NULL);

net/ipv4/netfilter/nft_fib_ipv4.c

···
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nft_fib.h>
 
+#include <net/inet_dscp.h>
 #include <net/ip_fib.h>
 #include <net/route.h>
 
···
 	if (priv->flags & NFTA_FIB_F_MARK)
 		fl4.flowi4_mark = pkt->skb->mark;
 
-	fl4.flowi4_tos = iph->tos & IPTOS_RT_MASK;
+	fl4.flowi4_tos = iph->tos & INET_DSCP_MASK;
 
 	if (priv->flags & NFTA_FIB_F_DADDR) {
 		fl4.daddr = iph->daddr;

net/ipv4/route.c

···
 		struct flowi4 fl4 = {
 			.daddr = iph->daddr,
 			.saddr = iph->saddr,
-			.flowi4_tos = iph->tos & IPTOS_RT_MASK,
+			.flowi4_tos = iph->tos & INET_DSCP_MASK,
 			.flowi4_oif = rt->dst.dev->ifindex,
 			.flowi4_iif = skb->dev->ifindex,
 			.flowi4_mark = skb->mark,
···
 	if (rt->rt_type != RTN_LOCAL)
 		goto skip_validate_source;
 
-	tos &= IPTOS_RT_MASK;
+	tos &= INET_DSCP_MASK;
 	err = fib_validate_source(skb, saddr, daddr, tos, 0, dev, in_dev, &tag);
 	if (err < 0)
 		goto martian_source;
···
 	struct fib_result res;
 	int err;
 
-	tos &= IPTOS_RT_MASK;
+	tos &= INET_DSCP_MASK;
 	rcu_read_lock();
 	err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
 	rcu_read_unlock();
···
 		skb->dev	= dev;
 		skb->mark	= mark;
 		err = ip_route_input_rcu(skb, dst, src,
-					 rtm->rtm_tos & IPTOS_RT_MASK, dev,
+					 rtm->rtm_tos & INET_DSCP_MASK, dev,
 					 &res);
 
 		rt = skb_rtable(skb);

net/ipv4/udp.c

···
 #include <net/addrconf.h>
 #include <net/udp_tunnel.h>
 #include <net/gro.h>
+#include <net/inet_dscp.h>
 #if IS_ENABLED(CONFIG_IPV6)
 #include <net/ipv6_stubs.h>
 #endif
···
 		if (!inet_sk(sk)->inet_daddr && in_dev)
 			return ip_mc_validate_source(skb, iph->daddr,
 						     iph->saddr,
-						     iph->tos & IPTOS_RT_MASK,
+						     iph->tos & INET_DSCP_MASK,
 						     skb->dev, in_dev, &itag);
 	}
 	return 0;