From be5650f8f47e8cffbbbcad08b71103685e971f20 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sun, 9 Jan 2022 17:11:24 +0100 Subject: [PATCH] netfilter: nft_bitwise: track register operations Check if the destination register already contains the data that this bitwise expression performs. This allows to skip this redundant operation. If the destination contains a different bitwise operation, cancel the register tracking information. If the destination contains no bitwise operation, update the register tracking information. Update the payload and meta expression to check if this bitwise operation has been already performed on the register. Hence, both the payload/meta and the bitwise expressions are reduced. There is also a special case: If source register != destination register and source register is not updated by a previous bitwise operation, then transfer selector from the source register to the destination register. Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables.h | 2 + net/netfilter/nft_bitwise.c | 95 +++++++++++++++++++++++++++++++++++++++ net/netfilter/nft_meta.c | 2 +- net/netfilter/nft_payload.c | 2 +- 4 files changed, 99 insertions(+), 2 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 1c37ce6..eaf55da 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -358,6 +358,8 @@ int nft_expr_clone(struct nft_expr *dst, struct nft_expr *src); void nft_expr_destroy(const struct nft_ctx *ctx, struct nft_expr *expr); int nft_expr_dump(struct sk_buff *skb, unsigned int attr, const struct nft_expr *expr); +bool nft_expr_reduce_bitwise(struct nft_regs_track *track, + const struct nft_expr *expr); struct nft_set_ext; diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c index 47b0dba..7b727d3 100644 --- a/net/netfilter/nft_bitwise.c +++ b/net/netfilter/nft_bitwise.c @@ -278,12 +278,52 @@ static int nft_bitwise_offload(struct nft_offload_ctx *ctx, return 0; } +static bool nft_bitwise_reduce(struct nft_regs_track *track, + const struct nft_expr *expr) +{ + const struct nft_bitwise *priv = nft_expr_priv(expr); + const struct nft_bitwise *bitwise; + + if (!track->regs[priv->sreg].selector) + return false; + + bitwise = nft_expr_priv(expr); + if (track->regs[priv->sreg].selector == track->regs[priv->dreg].selector && + track->regs[priv->dreg].bitwise && + track->regs[priv->dreg].bitwise->ops == expr->ops && + priv->sreg == bitwise->sreg && + priv->dreg == bitwise->dreg && + priv->op == bitwise->op && + priv->len == bitwise->len && + !memcmp(&priv->mask, &bitwise->mask, sizeof(priv->mask)) && + !memcmp(&priv->xor, &bitwise->xor, sizeof(priv->xor)) && + !memcmp(&priv->data, &bitwise->data, sizeof(priv->data))) { + track->cur = expr; + return true; + } + + if (track->regs[priv->sreg].bitwise) { + track->regs[priv->dreg].selector = NULL; + track->regs[priv->dreg].bitwise = NULL; + return false; + } + + if (priv->sreg != priv->dreg) { + track->regs[priv->dreg].selector = + track->regs[priv->sreg].selector; + } + track->regs[priv->dreg].bitwise = expr; + + return false; +} + static const struct nft_expr_ops nft_bitwise_ops = { .type = &nft_bitwise_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_bitwise)), .eval = nft_bitwise_eval, .init = nft_bitwise_init, .dump = nft_bitwise_dump, + .reduce = nft_bitwise_reduce, .offload = nft_bitwise_offload, }; @@ -385,12 +425,49 @@ static int nft_bitwise_fast_offload(struct nft_offload_ctx *ctx, return 0; } +static bool nft_bitwise_fast_reduce(struct nft_regs_track *track, + const struct nft_expr *expr) +{ + const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr); + const struct nft_bitwise_fast_expr *bitwise; + + if (!track->regs[priv->sreg].selector) + return false; + + bitwise = nft_expr_priv(expr); + if (track->regs[priv->sreg].selector == track->regs[priv->dreg].selector && + track->regs[priv->dreg].bitwise && + track->regs[priv->dreg].bitwise->ops == expr->ops && + priv->sreg == bitwise->sreg && + priv->dreg == bitwise->dreg && + priv->mask == bitwise->mask && + priv->xor == bitwise->xor) { + track->cur = expr; + return true; + } + + if (track->regs[priv->sreg].bitwise) { + track->regs[priv->dreg].selector = NULL; + track->regs[priv->dreg].bitwise = NULL; + return false; + } + + if (priv->sreg != priv->dreg) { + track->regs[priv->dreg].selector = + track->regs[priv->sreg].selector; + } + track->regs[priv->dreg].bitwise = expr; + + return false; +} + 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, + .reduce = nft_bitwise_fast_reduce, .offload = nft_bitwise_fast_offload, }; @@ -427,3 +504,21 @@ struct nft_expr_type nft_bitwise_type __read_mostly = { .maxattr = NFTA_BITWISE_MAX, .owner = THIS_MODULE, }; + +bool nft_expr_reduce_bitwise(struct nft_regs_track *track, + const struct nft_expr *expr) +{ + const struct nft_expr *last = track->last; + const struct nft_expr *next; + + if (expr == last) + return false; + + next = nft_expr_next(expr); + if (next->ops == &nft_bitwise_ops) + return nft_bitwise_reduce(track, next); + else if (next->ops == &nft_bitwise_fast_ops) + return nft_bitwise_fast_reduce(track, next); + + return false; +} diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c index 430f40b..40fe48f 100644 --- a/net/netfilter/nft_meta.c +++ b/net/netfilter/nft_meta.c @@ -774,7 +774,7 @@ static bool nft_meta_get_reduce(struct nft_regs_track *track, if (!track->regs[priv->dreg].bitwise) return true; - return false; + return nft_expr_reduce_bitwise(track, expr); } static const struct nft_expr_ops nft_meta_get_ops = { diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c index 7a7c66e..f518bf6 100644 --- a/net/netfilter/nft_payload.c +++ b/net/netfilter/nft_payload.c @@ -235,7 +235,7 @@ static bool nft_payload_reduce(struct nft_regs_track *track, if (!track->regs[priv->dreg].bitwise) return true; - return false; + return nft_expr_reduce_bitwise(track, expr); } static bool nft_payload_offload_mask(struct nft_offload_reg *reg, -- 2.7.4