Currently we just assume the element key as a u32 integer, regardless of
the set key length.
This is incorrect, for example, the tcp port number is only 16 bits.
So when we use the nft_payload expr to get the tcp dport and store
it to dreg, the dport will be stored at 0~15 bits, and 16~31 bits
will be padded with zero.
So the reg->data[dreg] will be looked like as below:
0 15 31
+-+-+-+-+-+-+-+-+-+-+-+-+
| tcp dport | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+
But for these big-endian systems, if we treate this register as a u32
integer, the element key will be larger than 65535, so the following
lookup in bitmap set will cause out of bound access.
Another issue is that if we add element with comments in bitmap
set(although the comments will be ignored eventually), the element will
vanish strangely. Because we treate the element key as a u32 integer, so
the comments will become the part of the element key, then the element
key will also be larger than 65535 and out of bound access will happen:
# nft add element t s { 1 comment test }
Since set->klen is 1 or 2, it's fine to treate the element key as a u8 or
u16 integer.
Fixes: 665153ff57 ("netfilter: nf_tables: add bitmap set type")
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
priv->bitmap_size stores the real bitmap size, instead of the full
struct nft_bitmap object.
Fixes: 665153ff57 ("netfilter: nf_tables: add bitmap set type")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch adds a new bitmap set type. This bitmap uses two bits to
represent one element. These two bits determine the element state in the
current and the future generation that fits into the nf_tables commit
protocol. When dumping elements back to userspace, the two bits are
expanded into a struct nft_set_ext object.
If no NFTA_SET_DESC_SIZE is specified, the existing automatic set
backend selection prefers bitmap over hash in case of keys whose size is
<= 16 bit. If the set size is know, the bitmap set type is selected if
with 16 bit kets and more than 390 elements in the set, otherwise the
hash table set implementation is used.
For 8 bit keys, the bitmap consumes 66 bytes. For 16 bit keys, the
bitmap takes 16388 bytes.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
