[nf-next,RFC,1/2] netfilter: nf_tables: add nft_setelem_parse_key()
diff mbox series

Message ID 20191202131407.500999-2-pablo@netfilter.org
State RFC
Delegated to: Pablo Neira
Headers show
Series
  • add NFTA_SET_ELEM_KEY_END
Related show

Commit Message

Pablo Neira Ayuso Dec. 2, 2019, 1:14 p.m. UTC
Add helper function to parse the set element key netlink attribute.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 56 ++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 24 deletions(-)

Comments

Stefano Brivio Dec. 5, 2019, 10:43 p.m. UTC | #1
Hi Pablo,

Just two nits:

On Mon,  2 Dec 2019 14:14:06 +0100
Pablo Neira Ayuso <pablo@netfilter.org> wrote:

> Add helper function to parse the set element key netlink attribute.
> 
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  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.

If the type is not NFT_DATA_VALUE, I guess we shouldn't pass
NFT_DATA_VALUE to nft_data_release() here.

Maybe nft_setelem_parse_key() could clean up after itself on error.
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).
Pablo Neira Ayuso Dec. 6, 2019, 7:45 p.m. UTC | #2
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@netfilter.org> wrote:
> 
> > Add helper function to parse the set element key netlink attribute.
> > 
> > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > ---
> >  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!
Stefano Brivio Dec. 7, 2019, 10:51 p.m. UTC | #3
On Fri, 6 Dec 2019 20:45:17 +0100
Pablo Neira Ayuso <pablo@netfilter.org> wrote:

> 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@netfilter.org> wrote:
> >   
> > > Add helper function to parse the set element key netlink attribute.
> > > 
> > > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > > ---
> > >  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.

Right you are, my bad, I mixed up err2: and err1: in nft_set_delelem()
and then forgot about err2: in nft_setelem_parse_key().

Well, on the other hand, 'return err;" and 'goto fail_elem;" would have
been easier to follow, but maybe it's just my taste. :)
Pablo Neira Ayuso Dec. 9, 2019, 8:44 p.m. UTC | #4
On Sat, Dec 07, 2019 at 11:51:38PM +0100, Stefano Brivio wrote:
> On Fri, 6 Dec 2019 20:45:17 +0100
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
[...]
> > On Thu, Dec 05, 2019 at 11:43:50PM +0100, Stefano Brivio wrote:
[...]
> > > 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.
> 
> Right you are, my bad, I mixed up err2: and err1: in nft_set_delelem()
> and then forgot about err2: in nft_setelem_parse_key().
> 
> Well, on the other hand, 'return err;" and 'goto fail_elem;" would have
> been easier to follow, but maybe it's just my taste. :)

Feel free to update this patch to use the goto tags you are
suggesting.

Thanks.

Patch
diff mbox series

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;
 	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);
 err1:
 	return err;
 }