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![Pablo Neira Ayuso](/assets/img/avatar_default.png)
This patch extends the set infrastructure to add a special catch-all set element. If the lookup fails to find an element (or range) in the set, then the catch-all element is selected. Users can specify a mapping, expression(s) and timeout to be attached to the catch-all element. This patch adds a catchall list to the set, this list might contain more than one single catch-all element (e.g. in case that the catch-all element is removed and a new one is added in the same transaction). However, most of the time, there will be either one element or no elements at all in this list. The catch-all element is identified via NFT_SET_ELEM_CATCHALL flag and such special element has no NFTA_SET_ELEM_KEY attribute. There is a new nft_set_elem_catchall object that stores a reference to the dummy catch-all element (catchall->elem) whose layout is the same of the set element type to reuse the existing set element codebase. The set size does not apply to the catch-all element, users can define a catch-all element even if the set is full. The check for valid set element flags hava been updates to report EOPNOTSUPP in case userspace requests flags that are not supported when using new userspace nftables and old kernel. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
243 lines
5.9 KiB
C
243 lines
5.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2009 Patrick McHardy <kaber@trash.net>
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*
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* Development of this code funded by Astaro AG (http://www.astaro.com/)
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/rbtree.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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struct nft_lookup {
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struct nft_set *set;
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u8 sreg;
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u8 dreg;
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bool invert;
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struct nft_set_binding binding;
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};
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void nft_lookup_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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const struct nft_lookup *priv = nft_expr_priv(expr);
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const struct nft_set *set = priv->set;
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const struct nft_set_ext *ext = NULL;
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const struct net *net = nft_net(pkt);
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bool found;
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found = set->ops->lookup(net, set, ®s->data[priv->sreg], &ext) ^
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priv->invert;
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if (!found) {
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ext = nft_set_catchall_lookup(net, set);
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if (!ext) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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}
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if (ext) {
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if (set->flags & NFT_SET_MAP)
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nft_data_copy(®s->data[priv->dreg],
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nft_set_ext_data(ext), set->dlen);
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nft_set_elem_update_expr(ext, regs, pkt);
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}
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}
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static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
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[NFTA_LOOKUP_SET] = { .type = NLA_STRING,
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.len = NFT_SET_MAXNAMELEN - 1 },
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[NFTA_LOOKUP_SET_ID] = { .type = NLA_U32 },
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[NFTA_LOOKUP_SREG] = { .type = NLA_U32 },
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[NFTA_LOOKUP_DREG] = { .type = NLA_U32 },
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[NFTA_LOOKUP_FLAGS] = { .type = NLA_U32 },
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};
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static int nft_lookup_init(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nlattr * const tb[])
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{
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struct nft_lookup *priv = nft_expr_priv(expr);
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u8 genmask = nft_genmask_next(ctx->net);
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struct nft_set *set;
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u32 flags;
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int err;
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if (tb[NFTA_LOOKUP_SET] == NULL ||
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tb[NFTA_LOOKUP_SREG] == NULL)
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return -EINVAL;
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set = nft_set_lookup_global(ctx->net, ctx->table, tb[NFTA_LOOKUP_SET],
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tb[NFTA_LOOKUP_SET_ID], genmask);
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if (IS_ERR(set))
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return PTR_ERR(set);
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err = nft_parse_register_load(tb[NFTA_LOOKUP_SREG], &priv->sreg,
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set->klen);
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if (err < 0)
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return err;
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if (tb[NFTA_LOOKUP_FLAGS]) {
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flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
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if (flags & ~NFT_LOOKUP_F_INV)
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return -EINVAL;
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if (flags & NFT_LOOKUP_F_INV) {
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if (set->flags & NFT_SET_MAP)
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return -EINVAL;
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priv->invert = true;
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}
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}
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if (tb[NFTA_LOOKUP_DREG] != NULL) {
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if (priv->invert)
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return -EINVAL;
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if (!(set->flags & NFT_SET_MAP))
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return -EINVAL;
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err = nft_parse_register_store(ctx, tb[NFTA_LOOKUP_DREG],
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&priv->dreg, NULL, set->dtype,
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set->dlen);
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if (err < 0)
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return err;
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} else if (set->flags & NFT_SET_MAP)
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return -EINVAL;
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priv->binding.flags = set->flags & NFT_SET_MAP;
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err = nf_tables_bind_set(ctx, set, &priv->binding);
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if (err < 0)
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return err;
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priv->set = set;
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return 0;
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}
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static void nft_lookup_deactivate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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enum nft_trans_phase phase)
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{
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struct nft_lookup *priv = nft_expr_priv(expr);
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nf_tables_deactivate_set(ctx, priv->set, &priv->binding, phase);
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}
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static void nft_lookup_activate(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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struct nft_lookup *priv = nft_expr_priv(expr);
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priv->set->use++;
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}
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static void nft_lookup_destroy(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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struct nft_lookup *priv = nft_expr_priv(expr);
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nf_tables_destroy_set(ctx, priv->set);
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}
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static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_lookup *priv = nft_expr_priv(expr);
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u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
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if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
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goto nla_put_failure;
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if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
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goto nla_put_failure;
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if (priv->set->flags & NFT_SET_MAP)
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if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -1;
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}
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static int nft_lookup_validate_setelem(const struct nft_ctx *ctx,
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struct nft_set *set,
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const struct nft_set_iter *iter,
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struct nft_set_elem *elem)
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{
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const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
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struct nft_ctx *pctx = (struct nft_ctx *)ctx;
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const struct nft_data *data;
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int err;
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if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
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*nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
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return 0;
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data = nft_set_ext_data(ext);
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switch (data->verdict.code) {
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case NFT_JUMP:
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case NFT_GOTO:
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pctx->level++;
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err = nft_chain_validate(ctx, data->verdict.chain);
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if (err < 0)
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return err;
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pctx->level--;
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break;
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default:
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break;
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}
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return 0;
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}
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static int nft_lookup_validate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nft_data **d)
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{
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const struct nft_lookup *priv = nft_expr_priv(expr);
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struct nft_set_iter iter;
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if (!(priv->set->flags & NFT_SET_MAP) ||
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priv->set->dtype != NFT_DATA_VERDICT)
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return 0;
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iter.genmask = nft_genmask_next(ctx->net);
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iter.skip = 0;
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iter.count = 0;
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iter.err = 0;
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iter.fn = nft_lookup_validate_setelem;
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priv->set->ops->walk(ctx, priv->set, &iter);
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if (iter.err < 0)
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return iter.err;
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return 0;
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}
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static const struct nft_expr_ops nft_lookup_ops = {
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.type = &nft_lookup_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
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.eval = nft_lookup_eval,
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.init = nft_lookup_init,
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.activate = nft_lookup_activate,
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.deactivate = nft_lookup_deactivate,
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.destroy = nft_lookup_destroy,
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.dump = nft_lookup_dump,
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.validate = nft_lookup_validate,
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};
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struct nft_expr_type nft_lookup_type __read_mostly = {
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.name = "lookup",
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.ops = &nft_lookup_ops,
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.policy = nft_lookup_policy,
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.maxattr = NFTA_LOOKUP_MAX,
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.owner = THIS_MODULE,
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};
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