From: Ido Schimmel <idosch@nvidia.com>
Date: Thu, 29 Aug 2024 06:54:55 +0000 (+0300)
Subject: ipv4: Unmask upper DSCP bits in ip_send_unicast_reply()
X-Git-Tag: v6.12-rc1~232^2~133^2~4
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=13f6538de2b845650e68996621489de547b0337e;p=linux-block.git

ipv4: Unmask upper DSCP bits in ip_send_unicast_reply()

The function calls flowi4_init_output() to initialize an IPv4 flow key
with which it then performs a FIB lookup using ip_route_output_flow().

'arg->tos' with which the TOS value in the IPv4 flow key (flowi4_tos) is
initialized contains the full DS field. Unmask the upper DSCP bits so
that in the future the FIB lookup could be performed according to the
full DSCP value.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b90d0f78ac80..eea443b7f65e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -77,6 +77,7 @@
 #include <net/inetpeer.h>
 #include <net/inet_ecn.h>
 #include <net/lwtunnel.h>
+#include <net/inet_dscp.h>
 #include <linux/bpf-cgroup.h>
 #include <linux/igmp.h>
 #include <linux/netfilter_ipv4.h>
@@ -1621,7 +1622,7 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 
 	flowi4_init_output(&fl4, oif,
 			   IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
-			   RT_TOS(arg->tos),
+			   arg->tos & INET_DSCP_MASK,
 			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
 			   ip_reply_arg_flowi_flags(arg),
 			   daddr, saddr,