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netfilter: nft_hash: add map lookups for hashing operations
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This patch creates new attributes to accept a map as argument and
then perform the lookup with the generated hash accordingly.

Both current hash functions are supported: Jenkins and Symmetric Hash.

Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Laura Garcia Liebana authored and Pablo Neira Ayuso committed May 17, 2018
1 parent 978d8f9 commit b9ccc07
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Showing 2 changed files with 134 additions and 1 deletion.
4 changes: 4 additions & 0 deletions include/uapi/linux/netfilter/nf_tables.h
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Original file line number Diff line number Diff line change
Expand Up @@ -856,6 +856,8 @@ enum nft_hash_types {
* @NFTA_HASH_SEED: seed value (NLA_U32)
* @NFTA_HASH_OFFSET: add this offset value to hash result (NLA_U32)
* @NFTA_HASH_TYPE: hash operation (NLA_U32: nft_hash_types)
* @NFTA_HASH_SET_NAME: name of the map to lookup (NLA_STRING)
* @NFTA_HASH_SET_ID: id of the map (NLA_U32)
*/
enum nft_hash_attributes {
NFTA_HASH_UNSPEC,
Expand All @@ -866,6 +868,8 @@ enum nft_hash_attributes {
NFTA_HASH_SEED,
NFTA_HASH_OFFSET,
NFTA_HASH_TYPE,
NFTA_HASH_SET_NAME,
NFTA_HASH_SET_ID,
__NFTA_HASH_MAX,
};
#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1)
Expand Down
131 changes: 130 additions & 1 deletion net/netfilter/nft_hash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ struct nft_jhash {
u32 modulus;
u32 seed;
u32 offset;
struct nft_set *map;
};

static void nft_jhash_eval(const struct nft_expr *expr,
Expand All @@ -35,14 +36,39 @@ static void nft_jhash_eval(const struct nft_expr *expr,
const void *data = &regs->data[priv->sreg];
u32 h;

h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
h = reciprocal_scale(jhash(data, priv->len, priv->seed),
priv->modulus);

regs->data[priv->dreg] = h + priv->offset;
}

static void nft_jhash_map_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_jhash *priv = nft_expr_priv(expr);
const void *data = &regs->data[priv->sreg];
const struct nft_set *map = priv->map;
const struct nft_set_ext *ext;
u32 result;
bool found;

result = reciprocal_scale(jhash(data, priv->len, priv->seed),
priv->modulus) + priv->offset;

found = map->ops->lookup(nft_net(pkt), map, &result, &ext);
if (!found)
return;

nft_data_copy(&regs->data[priv->dreg],
nft_set_ext_data(ext), map->dlen);
}

struct nft_symhash {
enum nft_registers dreg:8;
u32 modulus;
u32 offset;
struct nft_set *map;
};

static void nft_symhash_eval(const struct nft_expr *expr,
Expand All @@ -58,6 +84,28 @@ static void nft_symhash_eval(const struct nft_expr *expr,
regs->data[priv->dreg] = h + priv->offset;
}

static void nft_symhash_map_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_symhash *priv = nft_expr_priv(expr);
struct sk_buff *skb = pkt->skb;
const struct nft_set *map = priv->map;
const struct nft_set_ext *ext;
u32 result;
bool found;

result = reciprocal_scale(__skb_get_hash_symmetric(skb),
priv->modulus) + priv->offset;

found = map->ops->lookup(nft_net(pkt), map, &result, &ext);
if (!found)
return;

nft_data_copy(&regs->data[priv->dreg],
nft_set_ext_data(ext), map->dlen);
}

static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
[NFTA_HASH_SREG] = { .type = NLA_U32 },
[NFTA_HASH_DREG] = { .type = NLA_U32 },
Expand All @@ -66,6 +114,9 @@ static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
[NFTA_HASH_SEED] = { .type = NLA_U32 },
[NFTA_HASH_OFFSET] = { .type = NLA_U32 },
[NFTA_HASH_TYPE] = { .type = NLA_U32 },
[NFTA_HASH_SET_NAME] = { .type = NLA_STRING,
.len = NFT_SET_MAXNAMELEN - 1 },
[NFTA_HASH_SET_ID] = { .type = NLA_U32 },
};

static int nft_jhash_init(const struct nft_ctx *ctx,
Expand Down Expand Up @@ -115,6 +166,23 @@ static int nft_jhash_init(const struct nft_ctx *ctx,
NFT_DATA_VALUE, sizeof(u32));
}

static int nft_jhash_map_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_jhash *priv = nft_expr_priv(expr);
u8 genmask = nft_genmask_next(ctx->net);

nft_jhash_init(ctx, expr, tb);
priv->map = nft_set_lookup_global(ctx->net, ctx->table,
tb[NFTA_HASH_SET_NAME],
tb[NFTA_HASH_SET_ID], genmask);
if (IS_ERR(priv->map))
return PTR_ERR(priv->map);

return 0;
}

static int nft_symhash_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
Expand All @@ -141,6 +209,23 @@ static int nft_symhash_init(const struct nft_ctx *ctx,
NFT_DATA_VALUE, sizeof(u32));
}

static int nft_symhash_map_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_jhash *priv = nft_expr_priv(expr);
u8 genmask = nft_genmask_next(ctx->net);

nft_symhash_init(ctx, expr, tb);
priv->map = nft_set_lookup_global(ctx->net, ctx->table,
tb[NFTA_HASH_SET_NAME],
tb[NFTA_HASH_SET_ID], genmask);
if (IS_ERR(priv->map))
return PTR_ERR(priv->map);

return 0;
}

static int nft_jhash_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
Expand Down Expand Up @@ -168,6 +253,18 @@ static int nft_jhash_dump(struct sk_buff *skb,
return -1;
}

static int nft_jhash_map_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
const struct nft_jhash *priv = nft_expr_priv(expr);

if (nft_jhash_dump(skb, expr) ||
nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))
return -1;

return 0;
}

static int nft_symhash_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
Expand All @@ -188,6 +285,18 @@ static int nft_symhash_dump(struct sk_buff *skb,
return -1;
}

static int nft_symhash_map_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
const struct nft_symhash *priv = nft_expr_priv(expr);

if (nft_symhash_dump(skb, expr) ||
nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))
return -1;

return 0;
}

static struct nft_expr_type nft_hash_type;
static const struct nft_expr_ops nft_jhash_ops = {
.type = &nft_hash_type,
Expand All @@ -197,6 +306,14 @@ static const struct nft_expr_ops nft_jhash_ops = {
.dump = nft_jhash_dump,
};

static const struct nft_expr_ops nft_jhash_map_ops = {
.type = &nft_hash_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
.eval = nft_jhash_map_eval,
.init = nft_jhash_map_init,
.dump = nft_jhash_map_dump,
};

static const struct nft_expr_ops nft_symhash_ops = {
.type = &nft_hash_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
Expand All @@ -205,6 +322,14 @@ static const struct nft_expr_ops nft_symhash_ops = {
.dump = nft_symhash_dump,
};

static const struct nft_expr_ops nft_symhash_map_ops = {
.type = &nft_hash_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
.eval = nft_symhash_map_eval,
.init = nft_symhash_map_init,
.dump = nft_symhash_map_dump,
};

static const struct nft_expr_ops *
nft_hash_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
Expand All @@ -217,8 +342,12 @@ nft_hash_select_ops(const struct nft_ctx *ctx,
type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
switch (type) {
case NFT_HASH_SYM:
if (tb[NFTA_HASH_SET_NAME])
return &nft_symhash_map_ops;
return &nft_symhash_ops;
case NFT_HASH_JENKINS:
if (tb[NFTA_HASH_SET_NAME])
return &nft_jhash_map_ops;
return &nft_jhash_ops;
default:
break;
Expand Down

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