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netfilter: nft_payload: add optimized payload implementation for smal…
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…l loads

Add an optimized payload expression implementation for small (up to 4 bytes)
aligned data loads from the linear packet area.

This patch also includes original Patrick McHardy's entitled (nf_tables:
inline nft_payload_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 cb7dbfd commit c29b72e
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Showing 3 changed files with 81 additions and 28 deletions.
9 changes: 9 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 @@ -27,6 +27,15 @@ extern void nft_bitwise_module_exit(void);
extern int nft_byteorder_module_init(void);
extern void nft_byteorder_module_exit(void);

struct nft_payload {
enum nft_payload_bases base:8;
u8 offset;
u8 len;
enum nft_registers dreg:8;
};

extern const struct nft_expr_ops nft_payload_fast_ops;

extern int nft_payload_module_init(void);
extern void nft_payload_module_exit(void);

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31 changes: 30 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 @@ -32,6 +32,34 @@ static void nft_cmp_fast_eval(const struct nft_expr *expr,
data[NFT_REG_VERDICT].verdict = NFT_BREAK;
}

static bool nft_payload_fast_eval(const struct nft_expr *expr,
struct nft_data data[NFT_REG_MAX + 1],
const struct nft_pktinfo *pkt)
{
const struct nft_payload *priv = nft_expr_priv(expr);
const struct sk_buff *skb = pkt->skb;
struct nft_data *dest = &data[priv->dreg];
unsigned char *ptr;

if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
ptr = skb_network_header(skb);
else
ptr = skb_transport_header(skb);

ptr += priv->offset;

if (unlikely(ptr + priv->len >= skb_tail_pointer(skb)))
return false;

if (priv->len == 2)
*(u16 *)dest->data = *(u16 *)ptr;
else if (priv->len == 4)
*(u32 *)dest->data = *(u32 *)ptr;
else
*(u8 *)dest->data = *(u8 *)ptr;
return true;
}

unsigned int nft_do_chain(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
Expand Down Expand Up @@ -62,7 +90,8 @@ unsigned int nft_do_chain(const struct nf_hook_ops *ops,
nft_rule_for_each_expr(expr, last, rule) {
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, data);
else
else if (expr->ops != &nft_payload_fast_ops ||
!nft_payload_fast_eval(expr, data, &pkt))
expr->ops->eval(expr, data, &pkt);

if (data[NFT_REG_VERDICT].verdict != NFT_CONTINUE)
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69 changes: 42 additions & 27 deletions net/netfilter/nft_payload.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,6 @@
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>

struct nft_payload {
enum nft_payload_bases base:8;
u8 offset;
u8 len;
enum nft_registers dreg:8;
};

static void nft_payload_eval(const struct nft_expr *expr,
struct nft_data data[NFT_REG_MAX + 1],
const struct nft_pktinfo *pkt)
Expand Down Expand Up @@ -71,27 +64,9 @@ static int nft_payload_init(const struct nft_ctx *ctx,
struct nft_payload *priv = nft_expr_priv(expr);
int err;

if (tb[NFTA_PAYLOAD_DREG] == NULL ||
tb[NFTA_PAYLOAD_BASE] == NULL ||
tb[NFTA_PAYLOAD_OFFSET] == NULL ||
tb[NFTA_PAYLOAD_LEN] == NULL)
return -EINVAL;

priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
switch (priv->base) {
case NFT_PAYLOAD_LL_HEADER:
case NFT_PAYLOAD_NETWORK_HEADER:
case NFT_PAYLOAD_TRANSPORT_HEADER:
break;
default:
return -EOPNOTSUPP;
}

priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
if (priv->len == 0 ||
priv->len > FIELD_SIZEOF(struct nft_data, data))
return -EINVAL;

priv->dreg = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_DREG]));
err = nft_validate_output_register(priv->dreg);
Expand Down Expand Up @@ -124,9 +99,49 @@ static const struct nft_expr_ops nft_payload_ops = {
.dump = nft_payload_dump,
};

const struct nft_expr_ops nft_payload_fast_ops = {
.type = &nft_payload_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
.eval = nft_payload_eval,
.init = nft_payload_init,
.dump = nft_payload_dump,
};

static const struct nft_expr_ops *nft_payload_select_ops(const struct nlattr * const tb[])
{
enum nft_payload_bases base;
unsigned int offset, len;

if (tb[NFTA_PAYLOAD_DREG] == NULL ||
tb[NFTA_PAYLOAD_BASE] == NULL ||
tb[NFTA_PAYLOAD_OFFSET] == NULL ||
tb[NFTA_PAYLOAD_LEN] == NULL)
return ERR_PTR(-EINVAL);

base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
switch (base) {
case NFT_PAYLOAD_LL_HEADER:
case NFT_PAYLOAD_NETWORK_HEADER:
case NFT_PAYLOAD_TRANSPORT_HEADER:
break;
default:
return ERR_PTR(-EOPNOTSUPP);
}

offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
if (len == 0 || len > FIELD_SIZEOF(struct nft_data, data))
return ERR_PTR(-EINVAL);

if (len <= 4 && IS_ALIGNED(offset, len) && base != NFT_PAYLOAD_LL_HEADER)
return &nft_payload_fast_ops;
else
return &nft_payload_ops;
}

static struct nft_expr_type nft_payload_type __read_mostly = {
.name = "payload",
.ops = &nft_payload_ops,
.select_ops = nft_payload_select_ops,
.policy = nft_payload_policy,
.maxattr = NFTA_PAYLOAD_MAX,
.owner = THIS_MODULE,
Expand Down

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