net: fib_rules: Add DSCP selector attribute

The FIB rule TOS selector is implemented differently between IPv4 and
IPv6. In IPv4 it is used to match on the three "Type of Services" bits
specified in RFC 791, while in IPv6 is it is used to match on the six
DSCP bits specified in RFC 2474.

Add a new FIB rule attribute to allow matching on DSCP. The attribute
will be used to implement a 'dscp' selector in ip-rule with a consistent
behavior between IPv4 and IPv6.

For now, set the type of the attribute to 'NLA_REJECT' so that user
space will not be able to configure it. This restriction will be lifted
once both IPv4 and IPv6 support the new attribute.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20240911093748.3662015-2-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/fib_rules.h b/include/uapi/linux/fib_rules.h
index 232df14e1287a3297716f0c16a0632194a189d50..a6924dd3aff1701fe0d30d7bdea8a0b4997a9c69 100644 (file)
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -67,6 +67,7 @@ enum {
        FRA_IP_PROTO,   /* ip proto */
        FRA_SPORT_RANGE, /* sport */
        FRA_DPORT_RANGE, /* dport */
+       FRA_DSCP,       /* dscp */
        __FRA_MAX
 };
 

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 5a4eb744758c4e5d2d118a3eb9f08c5493a3e470..df41c05f723427489158b7038fab313ae793bb93 100644 (file)
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -766,7 +766,8 @@ static const struct nla_policy fib_rule_policy[FRA_MAX + 1] = {
        [FRA_PROTOCOL]  = { .type = NLA_U8 },
        [FRA_IP_PROTO]  = { .type = NLA_U8 },
        [FRA_SPORT_RANGE] = { .len = sizeof(struct fib_rule_port_range) },
-       [FRA_DPORT_RANGE] = { .len = sizeof(struct fib_rule_port_range) }
+       [FRA_DPORT_RANGE] = { .len = sizeof(struct fib_rule_port_range) },
+       [FRA_DSCP]      = { .type = NLA_REJECT },
 };
 
 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh,