On Fri, Feb 04, 2022 at 01:11:45PM +0100, Florian Westphal wrote:
> netlink_dump structure has a union of 'long args[6]' and a context
> buffer as scratch space.
>
> Convert ctnetlink to use a structure, its easier to read than the
> raw 'args' usage which comes with no type checks and no readable names.
>
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> net/netfilter/nf_conntrack_netlink.c | 36 ++++++++++++++++++----------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index ac438370f94a..3d9f9ee50294 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -58,6 +58,12 @@
>
> MODULE_LICENSE("GPL");
>
> +struct ctnetlink_list_dump_ctx {
> + struct nf_conn *last;
> + unsigned int cpu;
> + bool done;
> +};
> +
> static int ctnetlink_dump_tuples_proto(struct sk_buff *skb,
> const struct nf_conntrack_tuple *tuple,
> const struct nf_conntrack_l4proto *l4proto)
> @@ -1694,14 +1700,18 @@ static int ctnetlink_get_conntrack(struct sk_buff *skb,
>
> static int ctnetlink_done_list(struct netlink_callback *cb)
> {
> - if (cb->args[1])
> - nf_ct_put((struct nf_conn *)cb->args[1]);
> + struct ctnetlink_list_dump_ctx *ctx = (void *)cb->ctx;
Where is cb->ctx initialized?
> + if (ctx->last)
> + nf_ct_put(ctx->last);
> +
> return 0;
> }
>
> static int
> ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying)
> {
> + struct ctnetlink_list_dump_ctx *ctx = (void *)cb->ctx;
> struct nf_conn *ct, *last;
> struct nf_conntrack_tuple_hash *h;
> struct hlist_nulls_node *n;
> @@ -1712,12 +1722,12 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
> struct hlist_nulls_head *list;
> struct net *net = sock_net(skb->sk);
>
> - if (cb->args[2])
> + if (ctx->done)
> return 0;
>
> - last = (struct nf_conn *)cb->args[1];
> + last = ctx->last;
>
> - for (cpu = cb->args[0]; cpu < nr_cpu_ids; cpu++) {
> + for (cpu = ctx->cpu; cpu < nr_cpu_ids; cpu++) {
> struct ct_pcpu *pcpu;
>
> if (!cpu_possible(cpu))
> @@ -1731,10 +1741,10 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
> ct = nf_ct_tuplehash_to_ctrack(h);
> if (l3proto && nf_ct_l3num(ct) != l3proto)
> continue;
> - if (cb->args[1]) {
> + if (ctx->last) {
> if (ct != last)
> continue;
> - cb->args[1] = 0;
> + ctx->last = NULL;
> }
>
> /* We can't dump extension info for the unconfirmed
> @@ -1751,19 +1761,19 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
> if (res < 0) {
> if (!refcount_inc_not_zero(&ct->ct_general.use))
> continue;
> - cb->args[0] = cpu;
> - cb->args[1] = (unsigned long)ct;
> + ctx->cpu = cpu;
> + ctx->last = ct;
> spin_unlock_bh(&pcpu->lock);
> goto out;
> }
> }
> - if (cb->args[1]) {
> - cb->args[1] = 0;
> + if (ctx->last) {
> + ctx->last = NULL;
> goto restart;
> }
> spin_unlock_bh(&pcpu->lock);
> }
> - cb->args[2] = 1;
> + ctx->done = true;
> out:
> if (last)
> nf_ct_put(last);
> @@ -3877,6 +3887,8 @@ static int __init ctnetlink_init(void)
> {
> int ret;
>
> + BUILD_BUG_ON(sizeof(struct ctnetlink_list_dump_ctx) > sizeof_field(struct netlink_callback, ctx));
> +
> ret = nfnetlink_subsys_register(&ctnl_subsys);
> if (ret < 0) {
> pr_err("ctnetlink_init: cannot register with nfnetlink.\n");
> --
> 2.34.1
>
