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ipv4: fib_rules: Add DSCP mask matching

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Extend IPv4 FIB rules to match on DSCP using a mask. The mask is only
set in rules that match on DSCP (not TOS) and initialized to cover the
entire DSCP field if the mask attribute is not specified.

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/20250220080525.831924-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Ido Schimmel 2025-02-20 10:05:21 +02:00 • committed by Jakub Kicinski
parent ca4edd969a
commit 2ae00699b3
1 changed files with 44 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

47
net/ipv4/fib_rules.c
View file

@ -37,6 +37,7 @@ struct fib4_rule {
u8 dst_len;
u8 src_len;
dscp_t dscp;
dscp_t dscp_mask;
u8 dscp_full:1; /* DSCP or TOS selector */
__be32 src;
__be32 srcmask;
@ -192,7 +193,8 @@ INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
* 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))
if (r->dscp_full &&
(r->dscp ^ inet_dsfield_to_dscp(fl4->flowi4_tos)) & r->dscp_mask)
return 0;
else if (!r->dscp_full && r->dscp &&
!fib_dscp_masked_match(r->dscp, fl4))
@ -235,11 +237,35 @@ static int fib4_nl2rule_dscp(const struct nlattr *nla, struct fib4_rule *rule4,
}
rule4->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
rule4->dscp_mask = inet_dsfield_to_dscp(INET_DSCP_MASK);
rule4->dscp_full = true;
return 0;
}
static int fib4_nl2rule_dscp_mask(const struct nlattr *nla,
struct fib4_rule *rule4,
struct netlink_ext_ack *extack)
{
dscp_t dscp_mask;
if (!rule4->dscp_full) {
NL_SET_ERR_MSG_ATTR(extack, nla,
"Cannot specify DSCP mask without DSCP value");
return -EINVAL;
}
dscp_mask = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
if (rule4->dscp & ~dscp_mask) {
NL_SET_ERR_MSG_ATTR(extack, nla, "Invalid DSCP mask");
return -EINVAL;
}
rule4->dscp_mask = dscp_mask;
return 0;
}
static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
struct fib_rule_hdr *frh,
struct nlattr **tb,
@ -271,6 +297,10 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
fib4_nl2rule_dscp(tb[FRA_DSCP], rule4, extack) < 0)
goto errout;
if (tb[FRA_DSCP_MASK] &&
fib4_nl2rule_dscp_mask(tb[FRA_DSCP_MASK], rule4, extack) < 0)
goto errout;
/* split local/main if they are not already split */
err = fib_unmerge(net);
if (err)
@ -366,6 +396,14 @@ static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
return 0;
}
if (tb[FRA_DSCP_MASK]) {
dscp_t dscp_mask;
dscp_mask = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP_MASK]) << 2);
if (!rule4->dscp_full || rule4->dscp_mask != dscp_mask)
return 0;
}
#ifdef CONFIG_IP_ROUTE_CLASSID
if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
return 0;
@ -391,7 +429,9 @@ static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
if (rule4->dscp_full) {
frh->tos = 0;
if (nla_put_u8(skb, FRA_DSCP,
inet_dscp_to_dsfield(rule4->dscp) >> 2))
inet_dscp_to_dsfield(rule4->dscp) >> 2) ||
nla_put_u8(skb, FRA_DSCP_MASK,
inet_dscp_to_dsfield(rule4->dscp_mask) >> 2))
goto nla_put_failure;
} else {
frh->tos = inet_dscp_to_dsfield(rule4->dscp);
@ -418,7 +458,8 @@ 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(1); /* dscp */
+ nla_total_size(1) /* dscp */
+ nla_total_size(1); /* dscp mask */
}
static void fib4_rule_flush_cache(struct fib_rules_ops *ops)