Re: [PATCH v4 2/2] netfilter: nft_meta: support for time matching

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

Just a few nitpicks and we go :-)

On Tue, Aug 13, 2019 at 08:38:20PM +0200, Ander Juaristi wrote:
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 82abaa183fc3..67ae55e08518 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -799,6 +799,9 @@ enum nft_exthdr_attributes {
>   * @NFT_META_OIFKIND: packet output interface kind name (dev->rtnl_link_ops->kind)
>   * @NFT_META_BRI_IIFPVID: packet input bridge port pvid
>   * @NFT_META_BRI_IIFVPROTO: packet input bridge vlan proto
> + * @NFT_META_TIME: a UNIX timestamp

    * @NFT_META_TIME: time since 1970 (in nanoseconds)

Probably rename this to NFT_META_TIME_NS I'd suggest.

> + * @NFT_META_TIME_DAY: day of week

  + * @NFT_META_TIME_DAY: day of week (from 0 = Sunday to 6 = Saturday)

> + * @NFT_META_TIME_HOUR: hour of day

  + * @NFT_META_TIME_HOUR: hour of the day (in seconds)

>   */
>  enum nft_meta_keys {
>  	NFT_META_LEN,
> @@ -831,6 +834,9 @@ enum nft_meta_keys {
>  	NFT_META_OIFKIND,
>  	NFT_META_BRI_IIFPVID,
>  	NFT_META_BRI_IIFVPROTO,
> +	NFT_META_TIME,
> +	NFT_META_TIME_DAY,
> +	NFT_META_TIME_HOUR,
>  };
>  
>  /**
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index f1b1d948c07b..3e665a1a744a 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -28,6 +28,27 @@
>  
>  static DEFINE_PER_CPU(struct rnd_state, nft_prandom_state);

Probably a few constant definitions to be used in nft_meta_weekday().

#define NFT_NETA_SECS_PER_MINUTE        60
#define NFT_META_SECS_PER_HOUR          3600
#define NFT_META_SECS_PER_DAY           86400
#define NFT_META_DAYS_PER_WEEK          7

these numbers are easy to guess, but this helps along time to read
this code.

> +static u8 nft_meta_weekday(unsigned long secs)
> +{
> +	u8 wday;
> +	unsigned int dse;

Reverse definition, from longest to shortest line:

	unsigned int dse;
	u8 wday;

> +	secs -= 60 * sys_tz.tz_minuteswest;
> +	dse = secs / 86400;
> +	wday = (4 + dse) % 7;
> +
> +	return wday;
> +}
> +
> +static u32 nft_meta_hour(unsigned long secs)
> +{
> +	struct tm tm;
> +
> +	time64_to_tm(secs, 0, &tm);
> +
> +	return tm.tm_hour * 3600 + tm.tm_min * 60 + tm.tm_sec;
> +}
> +
>  void nft_meta_get_eval(const struct nft_expr *expr,
>  		       struct nft_regs *regs,
>  		       const struct nft_pktinfo *pkt)
> @@ -226,6 +247,15 @@ void nft_meta_get_eval(const struct nft_expr *expr,
>  			goto err;
>  		strncpy((char *)dest, out->rtnl_link_ops->kind, IFNAMSIZ);
>  		break;
> +	case NFT_META_TIME:
> +		nft_reg_store64(dest, ktime_get_real_ns());
> +		break;
> +	case NFT_META_TIME_DAY:
> +		nft_reg_store8(dest, nft_meta_weekday(get_seconds()));
> +		break;
> +	case NFT_META_TIME_HOUR:
> +		*dest = nft_meta_hour(get_seconds());
> +		break;
>  	default:
>  		WARN_ON(1);
>  		goto err;
> @@ -338,6 +368,15 @@ int nft_meta_get_init(const struct nft_ctx *ctx,
>  		len = sizeof(u8);
>  		break;
>  #endif
> +	case NFT_META_TIME:
> +		len = sizeof(u64);
> +		break;
> +	case NFT_META_TIME_DAY:
> +		len = sizeof(u8);
> +		break;
> +	case NFT_META_TIME_HOUR:
> +		len = sizeof(u32);
> +		break;
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> -- 
> 2.17.1
>