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Message-Id: <20201004194940.7368-12-pablo@netfilter.org>
Date: Sun, 4 Oct 2020 21:49:40 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH 11/11] netfilter: nf_tables: Implement fast bitwise expression
From: Phil Sutter <phil@....cc>
A typical use of bitwise expression is to mask out parts of an IP
address when matching on the network part only. Optimize for this common
use with a fast variant for NFT_BITWISE_BOOL-type expressions operating
on 32bit-sized values.
Signed-off-by: Phil Sutter <phil@....cc>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/netfilter/nf_tables_core.h | 9 ++
net/netfilter/nf_tables_core.c | 12 +++
net/netfilter/nft_bitwise.c | 141 +++++++++++++++++++++++--
3 files changed, 156 insertions(+), 6 deletions(-)
diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h
index df2d91c814cb..8657e6815b07 100644
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -23,6 +23,13 @@ extern struct nft_object_type nft_secmark_obj_type;
int nf_tables_core_module_init(void);
void nf_tables_core_module_exit(void);
+struct nft_bitwise_fast_expr {
+ u32 mask;
+ u32 xor;
+ enum nft_registers sreg:8;
+ enum nft_registers dreg:8;
+};
+
struct nft_cmp_fast_expr {
u32 data;
u32 mask;
@@ -68,6 +75,8 @@ struct nft_payload_set {
extern const struct nft_expr_ops nft_payload_fast_ops;
+extern const struct nft_expr_ops nft_bitwise_fast_ops;
+
extern struct static_key_false nft_counters_enabled;
extern struct static_key_false nft_trace_enabled;
diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index e92feacaf551..dbc2e945c98e 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -47,6 +47,16 @@ static inline void nft_trace_packet(struct nft_traceinfo *info,
}
}
+static void nft_bitwise_fast_eval(const struct nft_expr *expr,
+ struct nft_regs *regs)
+{
+ const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
+ u32 *src = ®s->data[priv->sreg];
+ u32 *dst = ®s->data[priv->dreg];
+
+ *dst = (*src & priv->mask) ^ priv->xor;
+}
+
static void nft_cmp_fast_eval(const struct nft_expr *expr,
struct nft_regs *regs)
{
@@ -175,6 +185,8 @@ nft_do_chain(struct nft_pktinfo *pkt, void *priv)
nft_rule_for_each_expr(expr, last, rule) {
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, ®s);
+ else if (expr->ops == &nft_bitwise_fast_ops)
+ nft_bitwise_fast_eval(expr, ®s);
else if (expr->ops != &nft_payload_fast_ops ||
!nft_payload_fast_eval(expr, ®s, pkt))
expr_call_ops_eval(expr, ®s, pkt);
diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index bc37d6c59db4..bbd773d74377 100644
--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -163,11 +163,6 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
u32 len;
int err;
- if (!tb[NFTA_BITWISE_SREG] ||
- !tb[NFTA_BITWISE_DREG] ||
- !tb[NFTA_BITWISE_LEN])
- return -EINVAL;
-
err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
if (err < 0)
return err;
@@ -292,9 +287,143 @@ static const struct nft_expr_ops nft_bitwise_ops = {
.offload = nft_bitwise_offload,
};
+static int
+nft_bitwise_extract_u32_data(const struct nlattr * const tb, u32 *out)
+{
+ struct nft_data_desc desc;
+ struct nft_data data;
+ int err = 0;
+
+ err = nft_data_init(NULL, &data, sizeof(data), &desc, tb);
+ if (err < 0)
+ return err;
+
+ if (desc.type != NFT_DATA_VALUE || desc.len != sizeof(u32)) {
+ err = -EINVAL;
+ goto err;
+ }
+ *out = data.data[0];
+err:
+ nft_data_release(&data, desc.type);
+ return err;
+}
+
+static int nft_bitwise_fast_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
+ int err;
+
+ priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
+ err = nft_validate_register_load(priv->sreg, sizeof(u32));
+ if (err < 0)
+ return err;
+
+ priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
+ err = nft_validate_register_store(ctx, priv->dreg, NULL,
+ NFT_DATA_VALUE, sizeof(u32));
+ if (err < 0)
+ return err;
+
+ if (tb[NFTA_BITWISE_DATA])
+ return -EINVAL;
+
+ if (!tb[NFTA_BITWISE_MASK] ||
+ !tb[NFTA_BITWISE_XOR])
+ return -EINVAL;
+
+ err = nft_bitwise_extract_u32_data(tb[NFTA_BITWISE_MASK], &priv->mask);
+ if (err < 0)
+ return err;
+
+ err = nft_bitwise_extract_u32_data(tb[NFTA_BITWISE_XOR], &priv->xor);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static int
+nft_bitwise_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+ const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
+ struct nft_data data;
+
+ if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
+ return -1;
+ if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
+ return -1;
+ if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(sizeof(u32))))
+ return -1;
+ if (nla_put_be32(skb, NFTA_BITWISE_OP, htonl(NFT_BITWISE_BOOL)))
+ return -1;
+
+ data.data[0] = priv->mask;
+ if (nft_data_dump(skb, NFTA_BITWISE_MASK, &data,
+ NFT_DATA_VALUE, sizeof(u32)) < 0)
+ return -1;
+
+ data.data[0] = priv->xor;
+ if (nft_data_dump(skb, NFTA_BITWISE_XOR, &data,
+ NFT_DATA_VALUE, sizeof(u32)) < 0)
+ return -1;
+
+ return 0;
+}
+
+static int nft_bitwise_fast_offload(struct nft_offload_ctx *ctx,
+ struct nft_flow_rule *flow,
+ const struct nft_expr *expr)
+{
+ const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
+ struct nft_offload_reg *reg = &ctx->regs[priv->dreg];
+
+ if (priv->xor || priv->sreg != priv->dreg || reg->len != sizeof(u32))
+ return -EOPNOTSUPP;
+
+ reg->mask.data[0] = priv->mask;
+ return 0;
+}
+
+const struct nft_expr_ops nft_bitwise_fast_ops = {
+ .type = &nft_bitwise_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_bitwise_fast_expr)),
+ .eval = NULL, /* inlined */
+ .init = nft_bitwise_fast_init,
+ .dump = nft_bitwise_fast_dump,
+ .offload = nft_bitwise_fast_offload,
+};
+
+static const struct nft_expr_ops *
+nft_bitwise_select_ops(const struct nft_ctx *ctx,
+ const struct nlattr * const tb[])
+{
+ int err;
+ u32 len;
+
+ if (!tb[NFTA_BITWISE_LEN] ||
+ !tb[NFTA_BITWISE_SREG] ||
+ !tb[NFTA_BITWISE_DREG])
+ return ERR_PTR(-EINVAL);
+
+ err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
+ if (err < 0)
+ return ERR_PTR(err);
+
+ if (len != sizeof(u32))
+ return &nft_bitwise_ops;
+
+ if (tb[NFTA_BITWISE_OP] &&
+ ntohl(nla_get_be32(tb[NFTA_BITWISE_OP])) != NFT_BITWISE_BOOL)
+ return &nft_bitwise_ops;
+
+ return &nft_bitwise_fast_ops;
+}
+
struct nft_expr_type nft_bitwise_type __read_mostly = {
.name = "bitwise",
- .ops = &nft_bitwise_ops,
+ .select_ops = nft_bitwise_select_ops,
.policy = nft_bitwise_policy,
.maxattr = NFTA_BITWISE_MAX,
.owner = THIS_MODULE,
--
2.20.1
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