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netfilter: nf_tables: relax set/map validation checks

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Its currently not allowed to perform queries on a map, for example:

table t {
	map m {
		typeof ip saddr : meta mark
		..

	chain c {
		ip saddr @m counter

will fail, because kernel requires that userspace provides a destination
register when the referenced set is a map.

However, internally there is no real distinction between sets and maps,
maps are just sets where each key is associated with a value.

Relax this so that maps can be used just like sets.

This allows to have rules that query if a given key exists
without making use of the associated value.

This also permits != checks which don't work for map lookups.

When no destination reg is given for a map, then permit this for named
maps.

Data and dump paths need to be updated to consider priv->dreg_set
instead of the 'set-is-a-map' check.

Checks in reduce and validate callbacks are not changed, this
can be relaxed later if a need arises.

Signed-off-by: Florian Westphal <fw@strlen.de>
This commit is contained in:
Florian Westphal 2023-05-12 14:19:47 +02:00
parent b50a8b0d57
commit a4878eeae3
1 changed files with 15 additions and 8 deletions
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23
net/netfilter/nft_lookup.c
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@ -19,6 +19,7 @@ struct nft_lookup {
struct nft_set *set;
u8 sreg;
u8 dreg;
bool dreg_set;
bool invert;
struct nft_set_binding binding;
};
@ -75,7 +76,7 @@ void nft_lookup_eval(const struct nft_expr *expr,
}
if (ext) {
if (set->flags & NFT_SET_MAP)
if (priv->dreg_set)
nft_data_copy(&regs->data[priv->dreg],
nft_set_ext_data(ext), set->dlen);
@ -122,11 +123,8 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
if (flags & ~NFT_LOOKUP_F_INV)
return -EINVAL;
if (flags & NFT_LOOKUP_F_INV) {
if (set->flags & NFT_SET_MAP)
return -EINVAL;
if (flags & NFT_LOOKUP_F_INV)
priv->invert = true;
}
}
if (tb[NFTA_LOOKUP_DREG] != NULL) {
@ -140,8 +138,17 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
set->dlen);
if (err < 0)
return err;
} else if (set->flags & NFT_SET_MAP)
return -EINVAL;
priv->dreg_set = true;
} else if (set->flags & NFT_SET_MAP) {
/* Map given, but user asks for lookup only (i.e. to
* ignore value assoicated with key).
*
* This makes no sense for anonymous maps since they are
* scoped to the rule, but for named sets this can be useful.
*/
if (set->flags & NFT_SET_ANONYMOUS)
return -EINVAL;
}
priv->binding.flags = set->flags & NFT_SET_MAP;
@ -188,7 +195,7 @@ static int nft_lookup_dump(struct sk_buff *skb,
goto nla_put_failure;
if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
goto nla_put_failure;
if (priv->set->flags & NFT_SET_MAP)
if (priv->dreg_set)
if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))