netfilter: nf_tables: reject mismatching sum of field_len with set key length

The field length description provides the length of each separated key
field in the concatenation, each field gets rounded up to 32-bits to
calculate the pipapo rule width from pipapo_init(). The set key length
provides the total size of the key aligned to 32-bits.

Register-based arithmetics still allows for combining mismatching set
key length and field length description, eg. set key length 10 and field
description [ 5, 4 ] leading to pipapo width of 12.

Cc: stable@vger.kernel.org
Fixes: 3ce67e3793f4 ("netfilter: nf_tables: do not allow mismatch field size and set key length")
Reported-by: Noam Rathaus <noamr@ssd-disclosure.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index c4af283356e741cc9ed473639060030775e0d942..e5662dc087c8c151c8623f62987b2eb7a9cd4082 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5065,7 +5065,7 @@ static int nft_set_desc_concat_parse(const struct nlattr *attr,
 static int nft_set_desc_concat(struct nft_set_desc *desc,
                               const struct nlattr *nla)
 {
-       u32 num_regs = 0, key_num_regs = 0;
+       u32 len = 0, num_regs;
        struct nlattr *attr;
        int rem, err, i;
 
@@ -5079,12 +5079,12 @@ static int nft_set_desc_concat(struct nft_set_desc *desc,
        }
 
        for (i = 0; i < desc->field_count; i++)
-               num_regs += DIV_ROUND_UP(desc->field_len[i], sizeof(u32));
+               len += round_up(desc->field_len[i], sizeof(u32));
 
-       key_num_regs = DIV_ROUND_UP(desc->klen, sizeof(u32));
-       if (key_num_regs != num_regs)
+       if (len != desc->klen)
                return -EINVAL;
 
+       num_regs = DIV_ROUND_UP(desc->klen, sizeof(u32));
        if (num_regs > NFT_REG32_COUNT)
                return -E2BIG;