netfilter: nft_fib: Convert nft_fib4_eval() to dscp_t.

Use ip4h_dscp() instead of reading iph->tos directly.

ip4h_dscp() returns a dscp_t value which is temporarily converted back
to __u8 with inet_dscp_to_dsfield(). When converting ->flowi4_tos to
dscp_t in the future, we'll only have to remove that
inet_dscp_to_dsfield() call.

Signed-off-by: Guillaume Nault <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>

net/ipv4/netfilter/nft_fib_ipv4.c

@@ -11,6 +11,7 @@
 #include <net/netfilter/nft_fib.h>
 
 #include <net/inet_dscp.h>
+#include <net/ip.h>
 #include <net/ip_fib.h>
 #include <net/route.h>
 
@@ -107,7 +108,7 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	if (priv->flags & NFTA_FIB_F_MARK)
 		fl4.flowi4_mark = pkt->skb->mark;
 
-	fl4.flowi4_tos = iph->tos & INET_DSCP_MASK;
+	fl4.flowi4_tos = inet_dscp_to_dsfield(ip4h_dscp(iph));
 
 	if (priv->flags & NFTA_FIB_F_DADDR) {
 		fl4.daddr = iph->daddr;