net: fib_rules: Enable DSCP mask usage

Allow user space to configure FIB rules that match on DSCP with a mask,
now that support has been added to the IPv4 and IPv6 address families.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20250220080525.831924-5-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/fib_rules.c

@@ -845,7 +845,7 @@ static const struct nla_policy fib_rule_policy[FRA_MAX + 1] = {
 	[FRA_FLOWLABEL_MASK] = { .type = NLA_BE32 },
 	[FRA_SPORT_MASK] = { .type = NLA_U16 },
 	[FRA_DPORT_MASK] = { .type = NLA_U16 },
-	[FRA_DSCP_MASK] = { .type = NLA_REJECT },
+	[FRA_DSCP_MASK] = NLA_POLICY_MASK(NLA_U8, INET_DSCP_MASK >> 2),
 };
 
 int fib_newrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,