Re: [PATCH net v5] net/sched: cls_flower: Reject invalid ct_state flags rules

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Tue, Feb 09, 2021 at 02:37:49PM +0800, wenxu@ucloud.cn wrote:
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -30,6 +30,11 @@
>  
>  #include <uapi/linux/netfilter/nf_conntrack_common.h>
>  
> +#define TCA_FLOWER_KEY_CT_FLAGS_MAX \
> +		((__TCA_FLOWER_KEY_CT_FLAGS_MAX - 1) << 1)
> +#define TCA_FLOWER_KEY_CT_FLAGS_MASK \
> +		(TCA_FLOWER_KEY_CT_FLAGS_MAX - 1)
> +
>  struct fl_flow_key {
>  	struct flow_dissector_key_meta meta;
>  	struct flow_dissector_key_control control;
> @@ -686,8 +691,10 @@ static void *fl_get(struct tcf_proto *tp, u32 handle)
>  	[TCA_FLOWER_KEY_ENC_IP_TTL_MASK] = { .type = NLA_U8 },
>  	[TCA_FLOWER_KEY_ENC_OPTS]	= { .type = NLA_NESTED },
>  	[TCA_FLOWER_KEY_ENC_OPTS_MASK]	= { .type = NLA_NESTED },
> -	[TCA_FLOWER_KEY_CT_STATE]	= { .type = NLA_U16 },
> -	[TCA_FLOWER_KEY_CT_STATE_MASK]	= { .type = NLA_U16 },
> +	[TCA_FLOWER_KEY_CT_STATE]	=
> +		NLA_POLICY_MASK(NLA_U16, TCA_FLOWER_KEY_CT_FLAGS_MASK),
> +	[TCA_FLOWER_KEY_CT_STATE_MASK]	=
> +		NLA_POLICY_MASK(NLA_U16, TCA_FLOWER_KEY_CT_FLAGS_MASK),
>  	[TCA_FLOWER_KEY_CT_ZONE]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_CT_ZONE_MASK]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_CT_MARK]	= { .type = NLA_U32 },
> @@ -1390,12 +1397,33 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key,
>  	return 0;
>  }
>  
> +static int fl_validate_ct_state(u16 state, struct nlattr *tb,
> +				struct netlink_ext_ack *extack)
> +{
> +	if (state && !(state & TCA_FLOWER_KEY_CT_FLAGS_TRACKED)) {
> +		NL_SET_ERR_MSG_ATTR(extack, tb,
> +				    "no trk, so no other flag can be set");

I just tested iproute2 and it can't report based on the attr here.
Nonetheless, that would be iproute2 job and not the errmsg, I think.

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

Thanks!

> +		return -EINVAL;
> +	}
> +
> +	if (state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
> +	    state & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED) {
> +		NL_SET_ERR_MSG_ATTR(extack, tb,
> +				    "new and est are mutually exclusive");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static int fl_set_key_ct(struct nlattr **tb,
>  			 struct flow_dissector_key_ct *key,
>  			 struct flow_dissector_key_ct *mask,
>  			 struct netlink_ext_ack *extack)
>  {
>  	if (tb[TCA_FLOWER_KEY_CT_STATE]) {
> +		int err;
> +
>  		if (!IS_ENABLED(CONFIG_NF_CONNTRACK)) {
>  			NL_SET_ERR_MSG(extack, "Conntrack isn't enabled");
>  			return -EOPNOTSUPP;
> @@ -1403,6 +1431,13 @@ static int fl_set_key_ct(struct nlattr **tb,
>  		fl_set_key_val(tb, &key->ct_state, TCA_FLOWER_KEY_CT_STATE,
>  			       &mask->ct_state, TCA_FLOWER_KEY_CT_STATE_MASK,
>  			       sizeof(key->ct_state));
> +
> +		err = fl_validate_ct_state(mask->ct_state,
> +					   tb[TCA_FLOWER_KEY_CT_STATE_MASK],
> +					   extack);
> +		if (err)
> +			return err;
> +
>  	}
>  	if (tb[TCA_FLOWER_KEY_CT_ZONE]) {
>  		if (!IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES)) {
> -- 
> 1.8.3.1
>