On Thu, Dec 26, 2013 at 04:38:01PM +0100, Arturo Borrero Gonzalez wrote:
> This patch adds kernel support for the meta expression in get/set flavour.
> The set operation indicates that a given packet has to be set with a property,
> currently one of mark, priority, nftrace.
> The get op is what was currently working: evaluate the given packet property.
>
> In case of nftrace, the value is always 1. Such behaviour is copied
> from net/netfilter/xt_TRACE.c
>
> NFTA_META_DREG and NFTA_META_SREG attributes are mutually exclusives.
Applied with minor comestic changes, thanks Arturo!
> Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@xxxxxxxxx>
> ---
> v1: initial release of the patch
> v2: address comments from Tomasz in the kernel side: respect the order of the
> enums. Also, other cleanups.
> v3: use a nftables register to set the given packet value. Drop secmark.
>
> include/uapi/linux/netfilter/nf_tables.h | 2
> net/netfilter/nft_meta.c | 149 +++++++++++++++++++++++++-----
> 2 files changed, 125 insertions(+), 26 deletions(-)
>
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 256d36b..2c38a54 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -553,11 +553,13 @@ enum nft_meta_keys {
> *
> * @NFTA_META_DREG: destination register (NLA_U32)
> * @NFTA_META_KEY: meta data item to load (NLA_U32: nft_meta_keys)
> + * @NFTA_META_SREG: source register (NLA_U32)
> */
> enum nft_meta_attributes {
> NFTA_META_UNSPEC,
> NFTA_META_DREG,
> NFTA_META_KEY,
> + NFTA_META_SREG,
> __NFTA_META_MAX
> };
> #define NFTA_META_MAX (__NFTA_META_MAX - 1)
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index 8c28220..7008247 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -21,12 +21,15 @@
>
> struct nft_meta {
> enum nft_meta_keys key:8;
> - enum nft_registers dreg:8;
> + union {
> + enum nft_registers dreg:8;
> + enum nft_registers sreg:8;
> + };
> };
>
> -static void nft_meta_eval(const struct nft_expr *expr,
> - struct nft_data data[NFT_REG_MAX + 1],
> - const struct nft_pktinfo *pkt)
> +static void nft_meta_get_eval(const struct nft_expr *expr,
> + struct nft_data data[NFT_REG_MAX + 1],
> + const struct nft_pktinfo *pkt)
> {
> const struct nft_meta *priv = nft_expr_priv(expr);
> const struct sk_buff *skb = pkt->skb;
> @@ -132,23 +135,50 @@ err:
> data[NFT_REG_VERDICT].verdict = NFT_BREAK;
> }
>
> +static void nft_meta_set_eval(const struct nft_expr *expr,
> + struct nft_data data[NFT_REG_MAX + 1],
> + const struct nft_pktinfo *pkt)
> +{
> + const struct nft_meta *meta = nft_expr_priv(expr);
> + struct sk_buff *skb = pkt->skb;
> + u32 value = data[meta->sreg].data[0];
> +
> + switch (meta->key) {
> + case NFT_META_MARK:
> + skb->mark = value;
> + break;
> + case NFT_META_PRIORITY:
> + skb->priority = value;
> + break;
> + case NFT_META_NFTRACE:
> + skb->nf_trace = 1;
> + break;
> + default:
> + WARN_ON(1);
> + }
> +}
> +
> static const struct nla_policy nft_meta_policy[NFTA_META_MAX + 1] = {
> [NFTA_META_DREG] = { .type = NLA_U32 },
> [NFTA_META_KEY] = { .type = NLA_U32 },
> + [NFTA_META_SREG] = { .type = NLA_U32 },
> };
>
> -static int nft_meta_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
> - const struct nlattr * const tb[])
> +static int nft_meta_init_validate_set(uint32_t key)
> {
> - struct nft_meta *priv = nft_expr_priv(expr);
> - int err;
> -
> - if (tb[NFTA_META_DREG] == NULL ||
> - tb[NFTA_META_KEY] == NULL)
> - return -EINVAL;
> + switch (key) {
> + case NFT_META_MARK:
> + case NFT_META_PRIORITY:
> + case NFT_META_NFTRACE:
> + return 0;
> + default:
> + return -1;
return -EOPNOTSUPP here instead.
> + }
> +}
>
> - priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));
> - switch (priv->key) {
> +static int nft_meta_init_validate_get(uint32_t key)
> +{
> + switch (key) {
> case NFT_META_LEN:
> case NFT_META_PROTOCOL:
> case NFT_META_PRIORITY:
> @@ -167,26 +197,66 @@ static int nft_meta_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
> #ifdef CONFIG_NETWORK_SECMARK
> case NFT_META_SECMARK:
> #endif
> - break;
> + return 0;
> default:
> - return -EOPNOTSUPP;
> + return -1;
> }
>
> - priv->dreg = ntohl(nla_get_be32(tb[NFTA_META_DREG]));
> - err = nft_validate_output_register(priv->dreg);
> - if (err < 0)
> - return err;
> - return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
> }
>
> -static int nft_meta_dump(struct sk_buff *skb, const struct nft_expr *expr)
> +static int nft_meta_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
> + const struct nlattr * const tb[])
> +{
> + struct nft_meta *priv = nft_expr_priv(expr);
> + int err;
> +
> + priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));
> +
> + if (tb[NFTA_META_DREG]) {
> + if (nft_meta_init_validate_get(priv->key) != 0)
> + return -EOPNOTSUPP;
Just for consistency with similar code in this function.
err = nft_meta_init_validate_get(...);
if (err < 0)
return err;
> +
> + priv->dreg = ntohl(nla_get_be32(tb[NFTA_META_DREG]));
> + err = nft_validate_output_register(priv->dreg);
> + if (err < 0)
> + return err;
> + return nft_validate_data_load(ctx, priv->dreg, NULL,
> + NFT_DATA_VALUE);
> + }
> +
> + if (nft_meta_init_validate_set(priv->key) != 0)
> + return -EOPNOTSUPP;
> +
> + priv->sreg = ntohl(nla_get_be32(tb[NFTA_META_SREG]));
> +
> + return 0;
> +}
> +
> +static int nft_meta_get_dump(struct sk_buff *skb,
> + const struct nft_expr *expr)
> {
> const struct nft_meta *priv = nft_expr_priv(expr);
>
> + if (nla_put_be32(skb, NFTA_META_KEY, htonl(priv->key)))
> + goto nla_put_failure;
> if (nla_put_be32(skb, NFTA_META_DREG, htonl(priv->dreg)))
> goto nla_put_failure;
> + return 0;
> +
> +nla_put_failure:
> + return -1;
> +}
> +
> +static int nft_meta_set_dump(struct sk_buff *skb,
> + const struct nft_expr *expr)
> +{
> + const struct nft_meta *priv = nft_expr_priv(expr);
> +
> if (nla_put_be32(skb, NFTA_META_KEY, htonl(priv->key)))
> goto nla_put_failure;
> + if (nla_put_be32(skb, NFTA_META_SREG, htonl(priv->sreg)))
> + goto nla_put_failure;
> +
> return 0;
>
> nla_put_failure:
> @@ -194,17 +264,44 @@ nla_put_failure:
> }
>
> static struct nft_expr_type nft_meta_type;
> -static const struct nft_expr_ops nft_meta_ops = {
> +static const struct nft_expr_ops nft_meta_get_ops = {
> .type = &nft_meta_type,
> .size = NFT_EXPR_SIZE(sizeof(struct nft_meta)),
> - .eval = nft_meta_eval,
> + .eval = nft_meta_get_eval,
> .init = nft_meta_init,
> - .dump = nft_meta_dump,
> + .dump = nft_meta_get_dump,
> };
>
> +static const struct nft_expr_ops nft_meta_set_ops = {
> + .type = &nft_meta_type,
> + .size = NFT_EXPR_SIZE(sizeof(struct nft_meta)),
> + .eval = nft_meta_set_eval,
> + .init = nft_meta_init,
> + .dump = nft_meta_set_dump,
> +};
> +
> +static const struct nft_expr_ops *
> +nft_meta_select_ops(const struct nft_ctx *ctx,
> + const struct nlattr * const tb[])
> +{
> + if (!tb[NFTA_META_KEY])
> + return ERR_PTR(-EINVAL);
> +
> + if (tb[NFTA_META_DREG] && tb[NFTA_META_SREG])
> + return ERR_PTR(-EINVAL);
> +
> + if (tb[NFTA_META_DREG])
> + return &nft_meta_get_ops;
> +
> + if (tb[NFTA_META_SREG])
> + return &nft_meta_set_ops;
> +
> + return ERR_PTR(-EINVAL);
> +}
> +
> static struct nft_expr_type nft_meta_type __read_mostly = {
> .name = "meta",
> - .ops = &nft_meta_ops,
> + .select_ops = &nft_meta_select_ops,
> .policy = nft_meta_policy,
> .maxattr = NFTA_META_MAX,
> .owner = THIS_MODULE,
>
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