From 0f3cd9b3697708c86a825ae3cedabf7be6fd3e72 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 23 Sep 2016 15:23:33 +0200 Subject: netfilter: nf_tables: add range expression Inverse ranges != [a,b] are not currently possible because rules are composites of && operations, and we need to express this: data < a || data > b This patch adds a new range expression. Positive ranges can be already through two cmp expressions: cmp(sreg, data, >=) cmp(sreg, data, <=) This new range expression provides an alternative way to express this. Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_range.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 net/netfilter/nft_range.c (limited to 'net/netfilter/nft_range.c') diff --git a/net/netfilter/nft_range.c b/net/netfilter/nft_range.c new file mode 100644 index 000000000000..c6d5358482d1 --- /dev/null +++ b/net/netfilter/nft_range.c @@ -0,0 +1,138 @@ +/* + * Copyright (c) 2016 Pablo Neira Ayuso + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +struct nft_range_expr { + struct nft_data data_from; + struct nft_data data_to; + enum nft_registers sreg:8; + u8 len; + enum nft_range_ops op:8; +}; + +static void nft_range_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + const struct nft_range_expr *priv = nft_expr_priv(expr); + bool mismatch; + int d1, d2; + + d1 = memcmp(®s->data[priv->sreg], &priv->data_from, priv->len); + d2 = memcmp(®s->data[priv->sreg], &priv->data_to, priv->len); + switch (priv->op) { + case NFT_RANGE_EQ: + mismatch = (d1 < 0 || d2 > 0); + break; + case NFT_RANGE_NEQ: + mismatch = (d1 >= 0 && d2 <= 0); + break; + } + + if (mismatch) + regs->verdict.code = NFT_BREAK; +} + +static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = { + [NFTA_RANGE_SREG] = { .type = NLA_U32 }, + [NFTA_RANGE_OP] = { .type = NLA_U32 }, + [NFTA_RANGE_FROM_DATA] = { .type = NLA_NESTED }, + [NFTA_RANGE_TO_DATA] = { .type = NLA_NESTED }, +}; + +static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_range_expr *priv = nft_expr_priv(expr); + struct nft_data_desc desc_from, desc_to; + int err; + + err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from), + &desc_from, tb[NFTA_RANGE_FROM_DATA]); + if (err < 0) + return err; + + err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to), + &desc_to, tb[NFTA_RANGE_TO_DATA]); + if (err < 0) + goto err1; + + if (desc_from.len != desc_to.len) { + err = -EINVAL; + goto err2; + } + + priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]); + err = nft_validate_register_load(priv->sreg, desc_from.len); + if (err < 0) + goto err2; + + priv->op = ntohl(nla_get_be32(tb[NFTA_RANGE_OP])); + priv->len = desc_from.len; + return 0; +err2: + nft_data_uninit(&priv->data_to, desc_to.type); +err1: + nft_data_uninit(&priv->data_from, desc_from.type); + return err; +} + +static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr) +{ + const struct nft_range_expr *priv = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg)) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op))) + goto nla_put_failure; + + if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from, + NFT_DATA_VALUE, priv->len) < 0 || + nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to, + NFT_DATA_VALUE, priv->len) < 0) + goto nla_put_failure; + return 0; + +nla_put_failure: + return -1; +} + +static struct nft_expr_type nft_range_type; +static const struct nft_expr_ops nft_range_ops = { + .type = &nft_range_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)), + .eval = nft_range_eval, + .init = nft_range_init, + .dump = nft_range_dump, +}; + +static struct nft_expr_type nft_range_type __read_mostly = { + .name = "range", + .ops = &nft_range_ops, + .policy = nft_range_policy, + .maxattr = NFTA_RANGE_MAX, + .owner = THIS_MODULE, +}; + +int __init nft_range_module_init(void) +{ + return nft_register_expr(&nft_range_type); +} + +void nft_range_module_exit(void) +{ + nft_unregister_expr(&nft_range_type); +} -- cgit v1.2.3