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.
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;
+ }
+}
- 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;
+
+ 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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