On Thu, Dec 05, 2019 at 11:43:50PM +0100, Stefano Brivio wrote:
> Hi Pablo,
>
> Just two nits:
>
> On Mon, 2 Dec 2019 14:14:06 +0100
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
>
> > Add helper function to parse the set element key netlink attribute.
> >
> > Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> > ---
> > net/netfilter/nf_tables_api.c | 56 ++++++++++++++++++++++++-------------------
> > 1 file changed, 32 insertions(+), 24 deletions(-)
> >
> > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> > index 0db2784fee9a..13e291fac26f 100644
> > --- a/net/netfilter/nf_tables_api.c
> > +++ b/net/netfilter/nf_tables_api.c
> > @@ -4490,11 +4490,31 @@ static int nft_setelem_parse_flags(const struct nft_set *set,
> > return 0;
> > }
> >
> > +static int nft_setelem_parse_key(struct nft_ctx *ctx, struct nft_set *set,
> > + struct nft_data *key, struct nlattr *attr)
> > +{
> > + struct nft_data_desc desc;
> > + int err;
> > +
> > + err = nft_data_init(ctx, key, sizeof(*key), &desc, attr);
> > + if (err < 0)
> > + goto err1;
> > +
> > + err = -EINVAL;
> > + if (desc.type != NFT_DATA_VALUE || desc.len != set->klen)
> > + goto err2;
> > +
> > + return 0;
> > +err2:
> > + nft_data_release(key, desc.type);
> > +err1:
> > + return err;
> > +}
> > +
> > static int nft_get_set_elem(struct nft_ctx *ctx, struct nft_set *set,
> > const struct nlattr *attr)
> > {
> > struct nlattr *nla[NFTA_SET_ELEM_MAX + 1];
> > - struct nft_data_desc desc;
> > struct nft_set_elem elem;
> > struct sk_buff *skb;
> > uint32_t flags = 0;
> > @@ -4513,15 +4533,11 @@ static int nft_get_set_elem(struct nft_ctx *ctx, struct nft_set *set,
> > if (err < 0)
> > return err;
> >
> > - err = nft_data_init(ctx, &elem.key.val, sizeof(elem.key), &desc,
> > - nla[NFTA_SET_ELEM_KEY]);
> > + err = nft_setelem_parse_key(ctx, set, &elem.key.val,
> > + nla[NFTA_SET_ELEM_KEY]);
> > if (err < 0)
> > return err;
> >
> > - err = -EINVAL;
> > - if (desc.type != NFT_DATA_VALUE || desc.len != set->klen)
> > - return err;
> > -
> > priv = set->ops->get(ctx->net, set, &elem, flags);
> > if (IS_ERR(priv))
> > return PTR_ERR(priv);
> > @@ -4720,13 +4736,13 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
> > {
> > struct nlattr *nla[NFTA_SET_ELEM_MAX + 1];
> > u8 genmask = nft_genmask_next(ctx->net);
> > - struct nft_data_desc d1, d2;
> > struct nft_set_ext_tmpl tmpl;
> > struct nft_set_ext *ext, *ext2;
> > struct nft_set_elem elem;
> > struct nft_set_binding *binding;
> > struct nft_object *obj = NULL;
> > struct nft_userdata *udata;
> > + struct nft_data_desc d2;
>
> At this point, this could simply be desc, or data_desc.
>
> > struct nft_data data;
> > enum nft_registers dreg;
> > struct nft_trans *trans;
> > @@ -4792,15 +4808,12 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
> > return err;
> > }
> >
> > - err = nft_data_init(ctx, &elem.key.val, sizeof(elem.key), &d1,
> > - nla[NFTA_SET_ELEM_KEY]);
> > + err = nft_setelem_parse_key(ctx, set, &elem.key.val,
> > + nla[NFTA_SET_ELEM_KEY]);
> > if (err < 0)
> > goto err1;
> > - err = -EINVAL;
> > - if (d1.type != NFT_DATA_VALUE || d1.len != set->klen)
> > - goto err2;
> >
> > - nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, d1.len);
> > + nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
> > if (timeout > 0) {
> > nft_set_ext_add(&tmpl, NFT_SET_EXT_EXPIRATION);
> > if (timeout != set->timeout)
> > @@ -4942,7 +4955,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
> > if (nla[NFTA_SET_ELEM_DATA] != NULL)
> > nft_data_release(&data, d2.type);
> > err2:
> > - nft_data_release(&elem.key.val, d1.type);
> > + nft_data_release(&elem.key.val, NFT_DATA_VALUE);
> > err1:
> > return err;
> > }
> > @@ -5038,7 +5051,6 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
> > {
> > struct nlattr *nla[NFTA_SET_ELEM_MAX + 1];
> > struct nft_set_ext_tmpl tmpl;
> > - struct nft_data_desc desc;
> > struct nft_set_elem elem;
> > struct nft_set_ext *ext;
> > struct nft_trans *trans;
> > @@ -5063,16 +5075,12 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
> > if (flags != 0)
> > nft_set_ext_add(&tmpl, NFT_SET_EXT_FLAGS);
> >
> > - err = nft_data_init(ctx, &elem.key.val, sizeof(elem.key), &desc,
> > - nla[NFTA_SET_ELEM_KEY]);
> > + err = nft_setelem_parse_key(ctx, set, &elem.key.val,
> > + nla[NFTA_SET_ELEM_KEY]);
> > if (err < 0)
> > goto err1;
> >
> > - err = -EINVAL;
> > - if (desc.type != NFT_DATA_VALUE || desc.len != set->klen)
> > - goto err2;
> > -
> > - nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, desc.len);
> > + nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
> >
> > err = -ENOMEM;
> > elem.priv = nft_set_elem_init(set, &tmpl, elem.key.val.data, NULL, 0,
> > @@ -5109,7 +5117,7 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
> > err3:
> > kfree(elem.priv);
> > err2:
> > - nft_data_release(&elem.key.val, desc.type);
> > + nft_data_release(&elem.key.val, NFT_DATA_VALUE);
>
> I'm not sure if this can actually happen, but in
> nft_setelem_parse_key() you are checking that the type is
> NFT_DATA_VALUE, and returning error if it's not.
Exactly.
> If the type is not NFT_DATA_VALUE, I guess we shouldn't pass
> NFT_DATA_VALUE to nft_data_release() here.
The new nft_setelem_parse_key() function makes sure that the key is
NFT_DATA_VALUE, otherwise bails out and calls nft_data_release() with
desc.type.
Then, moving forward in nft_add_set_elem() after the
nft_setelem_parse_key(), if an error occurs, nft_data_release() can be
called with NFT_DATA_VALUE, because that was already validated by
nft_setelem_parse_key().
> Maybe nft_setelem_parse_key() could clean up after itself on error.
It's doing so already, right? See err2: label.
> After all, nft_data_init() is now called from there.
>
> > err1:
> > return err;
> > }
>
> Otherwise, it looks good to me. Note that, while I'm working on
> integrating this with the rest of kernel changes right now, I haven't
> tested it in any way (that needs your changes for userspace).
Great.
Let me know if you have more questions, thanks!
