Re: [nf PATCH 2/5] netfilter: nf_tables: Add locking for NFT_MSG_GETRULE_RESET requests

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Sep 26, 2023 at 11:14:31AM +0200, Phil Sutter wrote:
> On Mon, Sep 25, 2023 at 12:47:14PM +0200, Pablo Neira Ayuso wrote:
> > On Sat, Sep 23, 2023 at 03:38:04AM +0200, Phil Sutter wrote:
> > [...]
> > > @@ -3598,60 +3618,107 @@ static int nf_tables_getrule(struct sk_buff *skb, const struct nfnl_info *info,
> > >  	struct net *net = info->net;
> > >  	struct nft_table *table;
> > >  	struct sk_buff *skb2;
> > > -	bool reset = false;
> > >  	int err;
> > >  
> > > -	if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
> > > -		struct netlink_dump_control c = {
> > > -			.start= nf_tables_dump_rules_start,
> > > -			.dump = nf_tables_dump_rules,
> > > -			.done = nf_tables_dump_rules_done,
> > > -			.module = THIS_MODULE,
> > > -			.data = (void *)nla,
> > > -		};
> > > -
> > > -		return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c);
> > > -	}
> > > -
> > >  	table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask, 0);
> > >  	if (IS_ERR(table)) {
> > >  		NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
> > > -		return PTR_ERR(table);
> > > +		return ERR_CAST(table);
> > 
> >                 return ERR_PTR(table);
> > 
> > for consistency and to make this batch slightly smaller?
> 
> ERR_PTR() expects a long arg, while 'table' is a pointer. The only valid
> alternatives are '(struct sk_buff *)table' and 'ERR_PTR(PTR_ERR(table)).

Then, you only need PTR_ERR(table) if you want to return int as it was
before?

> I don't quite understand what's the problem with ERR_CAST(), it seems to
> exist exactly for this purpose.

No problem, we have been using a different macro, patch description
does not describe why this is required.