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Date: Sat, 18 Jan 2020 21:14:17 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 21/21] netfilter: bitwise: add support for shifts.
From: Jeremy Sowden <jeremy@...zel.net>
Hitherto nft_bitwise has only supported boolean operations: NOT, AND, OR
and XOR. Extend it to do shifts as well.
Signed-off-by: Jeremy Sowden <jeremy@...zel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/uapi/linux/netfilter/nf_tables.h | 9 +++-
net/netfilter/nft_bitwise.c | 77 ++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 8bef0620bc4f..261864736b26 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -489,9 +489,13 @@ enum nft_immediate_attributes {
*
* @NFT_BITWISE_BOOL: mask-and-xor operation used to implement NOT, AND, OR and
* XOR boolean operations
+ * @NFT_BITWISE_LSHIFT: left-shift operation
+ * @NFT_BITWISE_RSHIFT: right-shift operation
*/
enum nft_bitwise_ops {
NFT_BITWISE_BOOL,
+ NFT_BITWISE_LSHIFT,
+ NFT_BITWISE_RSHIFT,
};
/**
@@ -506,11 +510,12 @@ enum nft_bitwise_ops {
* @NFTA_BITWISE_DATA: argument for non-boolean operations
* (NLA_NESTED: nft_data_attributes)
*
- * The bitwise expression performs the following operation:
+ * The bitwise expression supports boolean and shift operations. It implements
+ * the boolean operations by performing the following operation:
*
* dreg = (sreg & mask) ^ xor
*
- * which allow to express all bitwise operations:
+ * with these mask and xor values:
*
* mask xor
* NOT: 1 1
diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index 744008a527fb..0ed2281f03be 100644
--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -34,6 +34,32 @@ static void nft_bitwise_eval_bool(u32 *dst, const u32 *src,
dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
}
+static void nft_bitwise_eval_lshift(u32 *dst, const u32 *src,
+ const struct nft_bitwise *priv)
+{
+ u32 shift = priv->data.data[0];
+ unsigned int i;
+ u32 carry = 0;
+
+ for (i = DIV_ROUND_UP(priv->len, sizeof(u32)); i > 0; i--) {
+ dst[i - 1] = (src[i - 1] << shift) | carry;
+ carry = src[i - 1] >> (BITS_PER_TYPE(u32) - shift);
+ }
+}
+
+static void nft_bitwise_eval_rshift(u32 *dst, const u32 *src,
+ const struct nft_bitwise *priv)
+{
+ u32 shift = priv->data.data[0];
+ unsigned int i;
+ u32 carry = 0;
+
+ for (i = 0; i < DIV_ROUND_UP(priv->len, sizeof(u32)); i++) {
+ dst[i] = carry | (src[i] >> shift);
+ carry = src[i] << (BITS_PER_TYPE(u32) - shift);
+ }
+}
+
void nft_bitwise_eval(const struct nft_expr *expr,
struct nft_regs *regs, const struct nft_pktinfo *pkt)
{
@@ -45,6 +71,12 @@ void nft_bitwise_eval(const struct nft_expr *expr,
case NFT_BITWISE_BOOL:
nft_bitwise_eval_bool(dst, src, priv);
break;
+ case NFT_BITWISE_LSHIFT:
+ nft_bitwise_eval_lshift(dst, src, priv);
+ break;
+ case NFT_BITWISE_RSHIFT:
+ nft_bitwise_eval_rshift(dst, src, priv);
+ break;
}
}
@@ -97,6 +129,32 @@ static int nft_bitwise_init_bool(struct nft_bitwise *priv,
return err;
}
+static int nft_bitwise_init_shift(struct nft_bitwise *priv,
+ const struct nlattr *const tb[])
+{
+ struct nft_data_desc d;
+ int err;
+
+ if (tb[NFTA_BITWISE_MASK] ||
+ tb[NFTA_BITWISE_XOR])
+ return -EINVAL;
+
+ if (!tb[NFTA_BITWISE_DATA])
+ return -EINVAL;
+
+ err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &d,
+ tb[NFTA_BITWISE_DATA]);
+ if (err < 0)
+ return err;
+ if (d.type != NFT_DATA_VALUE || d.len != sizeof(u32) ||
+ priv->data.data[0] >= BITS_PER_TYPE(u32)) {
+ nft_data_release(&priv->data, d.type);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int nft_bitwise_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
@@ -131,6 +189,8 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
priv->op = ntohl(nla_get_be32(tb[NFTA_BITWISE_OP]));
switch (priv->op) {
case NFT_BITWISE_BOOL:
+ case NFT_BITWISE_LSHIFT:
+ case NFT_BITWISE_RSHIFT:
break;
default:
return -EOPNOTSUPP;
@@ -143,6 +203,10 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
case NFT_BITWISE_BOOL:
err = nft_bitwise_init_bool(priv, tb);
break;
+ case NFT_BITWISE_LSHIFT:
+ case NFT_BITWISE_RSHIFT:
+ err = nft_bitwise_init_shift(priv, tb);
+ break;
}
return err;
@@ -162,6 +226,15 @@ static int nft_bitwise_dump_bool(struct sk_buff *skb,
return 0;
}
+static int nft_bitwise_dump_shift(struct sk_buff *skb,
+ const struct nft_bitwise *priv)
+{
+ if (nft_data_dump(skb, NFTA_BITWISE_DATA, &priv->data,
+ NFT_DATA_VALUE, sizeof(u32)) < 0)
+ return -1;
+ return 0;
+}
+
static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_bitwise *priv = nft_expr_priv(expr);
@@ -180,6 +253,10 @@ static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
case NFT_BITWISE_BOOL:
err = nft_bitwise_dump_bool(skb, priv);
break;
+ case NFT_BITWISE_LSHIFT:
+ case NFT_BITWISE_RSHIFT:
+ err = nft_bitwise_dump_shift(skb, priv);
+ break;
}
return err;
--
2.11.0
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