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netfilter: nf_tables: add optimized data comparison for small values
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Add an optimized version of nft_data_cmp() that only handles values of to
4 bytes length.

This patch includes original Patrick McHardy's patch entitled (nf_tables:
inline nft_cmp_fast_eval() into main evaluation loop).

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Patrick McHardy authored and Pablo Neira Ayuso committed Oct 14, 2013
1 parent ef1f7df commit cb7dbfd
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Showing 3 changed files with 118 additions and 24 deletions.
8 changes: 8 additions & 0 deletions include/net/netfilter/nf_tables_core.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,14 @@ extern void nf_tables_core_module_exit(void);
extern int nft_immediate_module_init(void);
extern void nft_immediate_module_exit(void);

struct nft_cmp_fast_expr {
u32 data;
enum nft_registers sreg:8;
u8 len;
};

extern const struct nft_expr_ops nft_cmp_fast_ops;

extern int nft_cmp_module_init(void);
extern void nft_cmp_module_exit(void);

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18 changes: 17 additions & 1 deletion net/netfilter/nf_tables_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,18 @@
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>

static void nft_cmp_fast_eval(const struct nft_expr *expr,
struct nft_data data[NFT_REG_MAX + 1])
{
const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
u32 mask;

mask = ~0U >> (sizeof(priv->data) * BITS_PER_BYTE - priv->len);
if ((data[priv->sreg].data[0] & mask) == priv->data)
return;
data[NFT_REG_VERDICT].verdict = NFT_BREAK;
}

unsigned int nft_do_chain(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
Expand Down Expand Up @@ -48,7 +60,11 @@ unsigned int nft_do_chain(const struct nf_hook_ops *ops,
data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
nft_rule_for_each_expr(expr, last, rule) {
expr->ops->eval(expr, data, &pkt);
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, data);
else
expr->ops->eval(expr, data, &pkt);

if (data[NFT_REG_VERDICT].verdict != NFT_CONTINUE)
break;
}
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116 changes: 93 additions & 23 deletions net/netfilter/nft_cmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,32 +75,11 @@ static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
struct nft_data_desc desc;
int err;

if (tb[NFTA_CMP_SREG] == NULL ||
tb[NFTA_CMP_OP] == NULL ||
tb[NFTA_CMP_DATA] == NULL)
return -EINVAL;

priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
err = nft_validate_input_register(priv->sreg);
if (err < 0)
return err;

priv->op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
switch (priv->op) {
case NFT_CMP_EQ:
case NFT_CMP_NEQ:
case NFT_CMP_LT:
case NFT_CMP_LTE:
case NFT_CMP_GT:
case NFT_CMP_GTE:
break;
default:
return -EINVAL;
}

err = nft_data_init(NULL, &priv->data, &desc, tb[NFTA_CMP_DATA]);
if (err < 0)
return err;
BUG_ON(err < 0);

priv->len = desc.len;
return 0;
Expand Down Expand Up @@ -133,9 +112,100 @@ static const struct nft_expr_ops nft_cmp_ops = {
.dump = nft_cmp_dump,
};

static int nft_cmp_fast_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
struct nft_data_desc desc;
struct nft_data data;
u32 mask;
int err;

priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));

err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
BUG_ON(err < 0);
desc.len *= BITS_PER_BYTE;

mask = ~0U >> (sizeof(priv->data) * BITS_PER_BYTE - desc.len);
priv->data = data.data[0] & mask;
priv->len = desc.len;
return 0;
}

static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
struct nft_data data;

if (nla_put_be32(skb, NFTA_CMP_SREG, htonl(priv->sreg)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
goto nla_put_failure;

data.data[0] = priv->data;
if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
goto nla_put_failure;
return 0;

nla_put_failure:
return -1;
}

const struct nft_expr_ops nft_cmp_fast_ops = {
.type = &nft_cmp_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
.eval = NULL, /* inlined */
.init = nft_cmp_fast_init,
.dump = nft_cmp_fast_dump,
};

static const struct nft_expr_ops *nft_cmp_select_ops(const struct nlattr * const tb[])
{
struct nft_data_desc desc;
struct nft_data data;
enum nft_registers sreg;
enum nft_cmp_ops op;
int err;

if (tb[NFTA_CMP_SREG] == NULL ||
tb[NFTA_CMP_OP] == NULL ||
tb[NFTA_CMP_DATA] == NULL)
return ERR_PTR(-EINVAL);

sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
err = nft_validate_input_register(sreg);
if (err < 0)
return ERR_PTR(err);

op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
switch (op) {
case NFT_CMP_EQ:
case NFT_CMP_NEQ:
case NFT_CMP_LT:
case NFT_CMP_LTE:
case NFT_CMP_GT:
case NFT_CMP_GTE:
break;
default:
return ERR_PTR(-EINVAL);
}

err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
if (err < 0)
return ERR_PTR(err);

if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
return &nft_cmp_fast_ops;
else
return &nft_cmp_ops;
}

static struct nft_expr_type nft_cmp_type __read_mostly = {
.name = "cmp",
.ops = &nft_cmp_ops,
.select_ops = nft_cmp_select_ops,
.policy = nft_cmp_policy,
.maxattr = NFTA_CMP_MAX,
.owner = THIS_MODULE,
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