From 10fdd6d80e4c21ad48f3860d723f5b3b5965477b Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Thu, 1 Oct 2020 18:57:44 +0200 Subject: [PATCH] netfilter: nf_tables: Implement fast bitwise expression 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 Signed-off-by: Pablo Neira Ayuso --- 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, -- GitLab