Re: [nf PATCH v2 1/8] netfilter: nf_tables: Don't allocate nft_rule_dump_ctx

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

On Thu, Sep 28, 2023 at 06:52:37PM +0200, Phil Sutter wrote:
[...]

This whole chunk below looks like a cleanup to remove one indentation
level? Please add an initial patch for this.

>  static int nf_tables_dump_rules_start(struct netlink_callback *cb)
>  {
> +	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
>  	const struct nlattr * const *nla = cb->data;
> -	struct nft_rule_dump_ctx *ctx = NULL;
>  
> -	if (nla[NFTA_RULE_TABLE] || nla[NFTA_RULE_CHAIN]) {
> -		ctx = kzalloc(sizeof(*ctx), GFP_ATOMIC);
> -		if (!ctx)
> -			return -ENOMEM;
> +	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
>  
> -		if (nla[NFTA_RULE_TABLE]) {
> -			ctx->table = nla_strdup(nla[NFTA_RULE_TABLE],
> -							GFP_ATOMIC);
> -			if (!ctx->table) {
> -				kfree(ctx);
> -				return -ENOMEM;
> -			}
> -		}
> -		if (nla[NFTA_RULE_CHAIN]) {
> -			ctx->chain = nla_strdup(nla[NFTA_RULE_CHAIN],
> -						GFP_ATOMIC);
> -			if (!ctx->chain) {
> -				kfree(ctx->table);
> -				kfree(ctx);
> -				return -ENOMEM;
> -			}
> +	if (nla[NFTA_RULE_TABLE]) {
> +		ctx->table = nla_strdup(nla[NFTA_RULE_TABLE], GFP_ATOMIC);
> +		if (!ctx->table)
> +			return -ENOMEM;
> +	}
> +	if (nla[NFTA_RULE_CHAIN]) {
> +		ctx->chain = nla_strdup(nla[NFTA_RULE_CHAIN], GFP_ATOMIC);
> +		if (!ctx->chain) {
> +			kfree(ctx->table);
> +			return -ENOMEM;
>  		}
>  	}
> +	if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) == NFT_MSG_GETRULE_RESET)
> +		ctx->reset = true;
>  
> -	cb->data = ctx;
>  	return 0;
>  }
>  
>  static int nf_tables_dump_rules_done(struct netlink_callback *cb)
>  {
> -	struct nft_rule_dump_ctx *ctx = cb->data;
> +	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
>  
> -	if (ctx) {
> -		kfree(ctx->table);
> -		kfree(ctx->chain);
> -		kfree(ctx);
> -	}
> +	kfree(ctx->table);
> +	kfree(ctx->chain);
>  	return 0;
>  }
>  
> -- 
> 2.41.0
>