On 2020-01-15, at 10:29:07 +0100, Pablo Neira Ayuso wrote:
> On Tue, Jan 14, 2020 at 09:29:17PM +0000, Jeremy Sowden wrote:
> > Add a new bitwise netlink attribute that will be used by shift
> > operations to store the size of the shift.  It is not used by
> > boolean operations.
> >
> > Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
> > ---
> >  include/uapi/linux/netfilter/nf_tables.h | 2 ++
> >  net/netfilter/nft_bitwise.c              | 5 +++++
> >  2 files changed, 7 insertions(+)
> >
> > diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> > index cfda75725455..7cb85fd0d38e 100644
> > --- a/include/uapi/linux/netfilter/nf_tables.h
> > +++ b/include/uapi/linux/netfilter/nf_tables.h
> > @@ -503,6 +503,7 @@ enum nft_bitwise_ops {
> >   * @NFTA_BITWISE_MASK: mask value (NLA_NESTED: nft_data_attributes)
> >   * @NFTA_BITWISE_XOR: xor value (NLA_NESTED: nft_data_attributes)
> >   * @NFTA_BITWISE_OP: type of operation (NLA_U32: nft_bitwise_ops)
> > + * @NFTA_BITWISE_DATA: argument for non-boolean operations (NLA_U32)
> >   *
> >   * The bitwise expression performs the following operation:
> >   *
> > @@ -524,6 +525,7 @@ enum nft_bitwise_attributes {
> >  	NFTA_BITWISE_MASK,
> >  	NFTA_BITWISE_XOR,
> >  	NFTA_BITWISE_OP,
> > +	NFTA_BITWISE_DATA,
> >  	__NFTA_BITWISE_MAX
> >  };
> >  #define NFTA_BITWISE_MAX	(__NFTA_BITWISE_MAX - 1)
> > diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
> > index 1d9079ba2102..72abaa83a8ca 100644
> > --- a/net/netfilter/nft_bitwise.c
> > +++ b/net/netfilter/nft_bitwise.c
> > @@ -22,6 +22,7 @@ struct nft_bitwise {
> >  	u8			len;
> >  	struct nft_data		mask;
> >  	struct nft_data		xor;
> > +	u32			data;
>
> Could you make this struct nft_data?
>
> We can extend later on nft_bitwise to more operations. I was
> considering to (ab)use bitwise to implement increment and decrement. I
> think u32 should be enough in most cases, but I'd prefer to stick to
> one 128 bit word in this case. For shift this is obviously too much,
> but this would be leaving room for new operations requiring something
> larger than u32.

I did wonder about that. :) Will do.

J.