Subject: Re: [PATCH net-next v4 2/3] net: flower: add support for matching cfm fields

From: Ido Schimmel <[email-masked]>
Date: Sun, 30 Apr 2023 17:49:57 +0300

On Tue, Apr 25, 2023 at 11:16:29PM +0200, Zahari Doychev wrote:
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index cc49256d5318..5d77da484a88 100644
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -11,6 +11,7 @@
>  #include <linux/rhashtable.h>
>  #include <linux/workqueue.h>
>  #include <linux/refcount.h>
> +#include <linux/bitfield.h>
>  
>  #include <linux/if_ether.h>
>  #include <linux/in6.h>
> @@ -71,6 +72,7 @@ struct fl_flow_key {
>  	struct flow_dissector_key_num_of_vlans num_of_vlans;
>  	struct flow_dissector_key_pppoe pppoe;
>  	struct flow_dissector_key_l2tpv3 l2tpv3;
> +	struct flow_dissector_key_cfm cfm;
>  } __aligned(BITS_PER_LONG / 8); /* Ensure that we can do comparisons as longs. */
>  
>  struct fl_flow_mask_range {
> @@ -720,7 +722,7 @@ static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
>  	[TCA_FLOWER_KEY_PPPOE_SID]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_PPP_PROTO]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_L2TPV3_SID]	= { .type = NLA_U32 },
> -
> +	[TCA_FLOWER_KEY_CFM]		= { .type = NLA_NESTED },

"fl_policy" is used with nla_parse_nested_deprecated(). You can enable
strict validation for new attributes using the following diff:

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index fc9037685458..6bccfc1722ad 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -615,7 +615,8 @@ static void *fl_get(struct tcf_proto *tp, u32 handle)
 }
 
 static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
-       [TCA_FLOWER_UNSPEC]             = { .type = NLA_UNSPEC },
+       [TCA_FLOWER_UNSPEC]             = { .strict_start_type =
+                                               TCA_FLOWER_KEY_CFM },
        [TCA_FLOWER_CLASSID]            = { .type = NLA_U32 },
        [TCA_FLOWER_INDEV]              = { .type = NLA_STRING,
                                            .len = IFNAMSIZ },

>  };
>  
>  static const struct nla_policy
> @@ -769,6 +771,11 @@ mpls_stack_entry_policy[TCA_FLOWER_KEY_MPLS_OPT_LSE_MAX + 1] = {
>  	[TCA_FLOWER_KEY_MPLS_OPT_LSE_LABEL]    = { .type = NLA_U32 },
>  };
>  
> +static const struct nla_policy cfm_opt_policy[TCA_FLOWER_KEY_CFM_OPT_MAX] = {
> +	[TCA_FLOWER_KEY_CFM_MD_LEVEL]	= NLA_POLICY_MAX(NLA_U8, 7),

Instead of 7, can you use FIELD_MAX(FLOW_DIS_CFM_MDL_MASK) like you did
in the previous version?

> +	[TCA_FLOWER_KEY_CFM_OPCODE]	= { .type = NLA_U8 },
> +};