From b9455fef8b1fc662369d982fe97dc66e6c332699 Mon Sep 17 00:00:00 2001
From: Ido Schimmel <idosch@nvidia.com>
Date: Wed, 11 Sep 2024 12:37:44 +0300
Subject: [PATCH] ipv4: fib_rules: Add DSCP selector support
Implement support for the new DSCP selector that allows IPv4 FIB rules
to match on the entire DSCP field, unlike the existing TOS selector that
only matches on the three lower DSCP bits.
Differentiate between both selectors by adding a new bit in the IPv4 FIB
rule structure (in an existing one byte hole) that is only set when the
'FRA_DSCP' attribute is specified by user space. Reject rules that use
both selectors.
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/20240911093748.3662015-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/ipv4/fib_rules.c | 54 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 50 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index c26776b71e97f..b07292d50ee76 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -37,6 +37,7 @@ struct fib4_rule {
u8 dst_len;
u8 src_len;
dscp_t dscp;
+ u8 dscp_full:1; /* DSCP or TOS selector */
__be32 src;
__be32 srcmask;
__be32 dst;
@@ -186,7 +187,15 @@ INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
((daddr ^ r->dst) & r->dstmask))
return 0;
- if (r->dscp && !fib_dscp_masked_match(r->dscp, fl4))
+ /* When DSCP selector is used we need to match on the entire DSCP field
+ * in the flow information structure. When TOS selector is used we need
+ * to mask the upper three DSCP bits prior to matching to maintain
+ * legacy behavior.
+ */
+ if (r->dscp_full && r->dscp != inet_dsfield_to_dscp(fl4->flowi4_tos))
+ return 0;
+ else if (!r->dscp_full && r->dscp &&
+ !fib_dscp_masked_match(r->dscp, fl4))
return 0;
if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
@@ -217,6 +226,20 @@ static struct fib_table *fib_empty_table(struct net *net)
return NULL;
}
+static int fib4_nl2rule_dscp(const struct nlattr *nla, struct fib4_rule *rule4,
+ struct netlink_ext_ack *extack)
+{
+ if (rule4->dscp) {
+ NL_SET_ERR_MSG(extack, "Cannot specify both TOS and DSCP");
+ return -EINVAL;
+ }
+
+ rule4->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
+ rule4->dscp_full = true;
+
+ return 0;
+}
+
static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
struct fib_rule_hdr *frh,
struct nlattr **tb,
@@ -238,6 +261,10 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
}
rule4->dscp = inet_dsfield_to_dscp(frh->tos);
+ if (tb[FRA_DSCP] &&
+ fib4_nl2rule_dscp(tb[FRA_DSCP], rule4, extack) < 0)
+ goto errout;
+
/* split local/main if they are not already split */
err = fib_unmerge(net);
if (err)
@@ -320,9 +347,19 @@ static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
if (frh->dst_len && (rule4->dst_len != frh->dst_len))
return 0;
- if (frh->tos && inet_dscp_to_dsfield(rule4->dscp) != frh->tos)
+ if (frh->tos &&
+ (rule4->dscp_full ||
+ inet_dscp_to_dsfield(rule4->dscp) != frh->tos))
return 0;
+ if (tb[FRA_DSCP]) {
+ dscp_t dscp;
+
+ dscp = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP]) << 2);
+ if (!rule4->dscp_full || rule4->dscp != dscp)
+ return 0;
+ }
+
#ifdef CONFIG_IP_ROUTE_CLASSID
if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
return 0;
@@ -344,7 +381,15 @@ static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
frh->dst_len = rule4->dst_len;
frh->src_len = rule4->src_len;
- frh->tos = inet_dscp_to_dsfield(rule4->dscp);
+
+ if (rule4->dscp_full) {
+ frh->tos = 0;
+ if (nla_put_u8(skb, FRA_DSCP,
+ inet_dscp_to_dsfield(rule4->dscp) >> 2))
+ goto nla_put_failure;
+ } else {
+ frh->tos = inet_dscp_to_dsfield(rule4->dscp);
+ }
if ((rule4->dst_len &&
nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
@@ -366,7 +411,8 @@ static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
{
return nla_total_size(4) /* dst */
+ nla_total_size(4) /* src */
- + nla_total_size(4); /* flow */
+ + nla_total_size(4) /* flow */
+ + nla_total_size(1); /* dscp */
}
static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
--
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