netfilter: nf_tables: nft_meta module get/set ops

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 the nftrace case, the value is always 1. Such behaviour is copied
from net/netfilter/xt_TRACE.c

The NFTA_META_DREG and NFTA_META_SREG attributes are mutually
exclusives.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index b25481e16f0ae52c61e833eea311b93ba8e10234..aa86a15293e10692b7a04c34990600fbfdbba44d 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -555,11 +555,13 @@ 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 8c28220a90b34baa013620d0ab13fdaf5355a33e..1ceaaa6dfe722406d9cac8a73a3a46566e11a8ea 100644 (file)
--- 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 -EOPNOTSUPP;
+       }
+}
 
-       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 +197,69 @@ 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;
        }
 
-       priv->dreg = ntohl(nla_get_be32(tb[NFTA_META_DREG]));
-       err = nft_validate_output_register(priv->dreg);
+}
+
+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]) {
+               err = nft_meta_init_validate_get(priv->key);
+               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);
+       }
+
+       err = nft_meta_init_validate_set(priv->key);
        if (err < 0)
                return err;
-       return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
+
+       priv->sreg = ntohl(nla_get_be32(tb[NFTA_META_SREG]));
+
+       return 0;
 }
 
-static int nft_meta_dump(struct sk_buff *skb, const struct nft_expr *expr)
+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 +267,44 @@ 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] == NULL)
+               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,